review article antioxidant capacity determination in plants and … · 2019. 7. 30. · review...

Review ArticleAntioxidant Capacity Determination in Plants andPlant-Derived Products A Review

Aurelia Magdalena Pisoschi1 Aneta Pop1 Carmen Cimpeanu2 and Gabriel Predoi1

1Faculty of Veterinary Medicine University of Agronomic Sciences and Veterinary Medicine of Bucharest105 Splaiul Independentei Sector 5 050097 Bucharest Romania2Faculty of Land Reclamation and Environmental Engineering University of Agronomic Sciences and Veterinary Medicine ofBucharest 59 Marasti Blvd Sector 1 011464 Bucharest Romania

Correspondence should be addressed to Aurelia Magdalena Pisoschi aureliamagdalenapisoschiyahooro

Received 26 June 2016 Revised 24 September 2016 Accepted 10 October 2016

Academic Editor Jerzy Kruk

Copyright copy 2016 Aurelia Magdalena Pisoschi et al This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

The present paper aims at reviewing and commenting on the analytical methods applied to antioxidant and antioxidant capacityassessment in plant-derived products Aspects related to oxidative stress reactive oxidative speciesrsquo influence on key biomoleculesand antioxidant benefits and modalities of action are discussed Also the oxidant-antioxidant balance is critically discussed Theconventional and nonconventional extraction procedures applied prior to analysis are also presented as the extraction step is ofpivotal importance for isolation and concentration of the compound(s) of interest before analysis Then the chromatographicspectrometric and electrochemical methods for antioxidant and antioxidant capacity determination in plant-derived products aredetailed with respect to their principles characteristics and specific applications Peculiarities related to the matrix characteristicsand other factors influencing themethodrsquos performances are discussedHealth benefits of plants and derived products are describedas indicated in the original source Finally critical and conclusive aspects are given when it comes to the choice of a particularextraction procedure and detection method which should consider the nature of the sample prevalent antioxidantantioxidantclass and the mechanism underlying each technique Advantages and disadvantages are discussed for each method

1 Introduction

Metabolism implies oxidative processes vital in cell survivalIn the course of molecular oxygen stepwise reduction aseries of reactive oxygenated species occur [1ndash3] Reactivespecies may be oxygenatednitrogenated free radicals definedas chemical species possessing an unpaired electron in thevalence shell (superoxide anion radical O2

∙minus hydroxyl HO∙hydroperoxyl HO2

∙ peroxyl ROO∙ alkoxyl RO∙ nitric oxideNO∙ peroxynitrite ONOOminus and nitrogen dioxide NO2) orneutral molecules (H2O2 or HClO) [4ndash7]

Free radicals generated in aerobic metabolism areinvolved in a series of regulatory processes such as cell prolif-eration apoptosis and gene expression When generated inexcess free radicals can counteract the defense capability ofthe antioxidant system impairing the essential biomoleculesin the cell by oxidizing membrane lipids cell proteinscarbohydrates DNA and enzymes Oxidative stress results

in cytotoxic compounds occurrence (malonyl dialdehyde 4-hydroxynonenal) and alters the oxidant-antioxidant balance(redox homeostasis) that characterizes normal cell function-ing [2ndash4]

With respect to alteration in the protein structure aminoacid oxidation free radical-induced cleavage and cross-linking due to reaction with lipid peroxidation productsmay occur [8] In nucleic acids structural alterations implygeneration of base-free sites deletions oxidation of basesframe shifts strand breaks DNA-protein cross-links andchromosomal arrangements The peroxyl radicals and theFenton-generated OH radicals can induce the oxidationnot only of purine and pyrimidine bases but also of thedeoxyribose moiety [9 10] Regarding influences that involvesugar chemistry oxygenated free radicals which resulted inearly glycation stages have been proven to be contributorsto glycoxidative damage glycolaldehyde that results in theinitial stages of nonenzymatic glycosylation is noncyclizable

Hindawi Publishing CorporationOxidative Medicine and Cellular LongevityVolume 2016 Article ID 9130976 36 pageshttpdxdoiorg10115520169130976

2 Oxidative Medicine and Cellular Longevity

and may undergo tautomerization yielding enediols thatare easily subject to autooxidation This step is initiatedand propagated by superoxide radical 120572- and 120573-dicarbonylsmay also result during this glycolaldehyde autooxidation [11]Peroxidation of lipids means primarily the attack to the fattyacidrsquos chain by a radical which abstracts a hydrogen atomfrom a methylene group with polyunsaturated fatty acidsbeing the most susceptible to undergo this process OH∙ asone of the most active radical species and HO2

∙ attack lipidsubstrates (L-H) yielding the corresponding lipid radicals L∙The attack on polyunsaturated fatty acids by singlet oxygencan yield lipid peroxides [12 13]

In recent studies it has been repeatedly asserted thatoxidative stress not only is not limited to free radical-induceddamage on biomolecules but also involves perturbation ofcellular redox status which has been described as ldquoa disrup-tion in redox signaling and controlrdquo hence the antioxidantsystem implies more than mere free radical capture [14ndash17]

Oxidative stress-induced pathology includes cancer [1819] cardiovascular disease [20] neural disorders [21]Alzheimerrsquos disease [22] mild cognitive impairment [23]Parkinsonrsquos disease [24] alcohol induced liver disease [25]ulcerative colitis [26] atherosclerosis [27] and aging [28]

The antioxidant action mechanism cannot be under-stood without describing the model lipid peroxidation incell membranes or foodstuffs a radical mechanism thatthese biomolecules undergowith initiation propagation andchain termination stages which is promoted by heat lightand ionizing radiation or by metal ions or metalloproteins[29ndash31]

Initiation

LH + R∙ 997888rarr L∙ + RH (1)

LH is the lipid substrate R∙ is the initiating oxidizing radicaland L∙ is the allyl radical endowed with high reactivity

Propagation

L∙ +O2 997888rarr LOO∙

LOO∙ + LH 997888rarr L∙ + LOOH(2)

So during this step the lipid peroxyl radicals LOO∙ act aschain carriers further oxidizing the lipid substrate and gen-erating lipid hydroperoxides (LOOH) which can decomposeinto alcohols aldehydes alkyl formates ketones hydrocar-bons and radicals such as lipid alkoxyl radical LO∙ [3 32]

Branching

LOOH 997888rarr LO∙ +HO∙

2LOOH 997888rarr LOO∙ + LO∙ +H2O(3)

The decay of lipid hydroperoxides often takes place in thepresence of transition metal ions generating lipid peroxyland lipid alkoxyl radicals

LOOH +M119899+ +H+ 997888rarr LO∙ +M(119899+1)+ +H2O

LOOH +M(119899+1)+ +OHminus 997888rarr LOO∙ +M119899+ +H2O(4)

Termination implies the combination of radicals to formnonradical chemical species

LO∙ + LO∙ 997888rarr nonradical products

LOO∙ + LOO∙ 997888rarr nonradical products

LO∙ + LOO∙ 997888rarr nonradical products

(5)

Antioxidants can act as chain breakers scavenging chaininitiating radicals like hydroxyl alkoxyl or peroxyl quench-ing singlet oxygen decomposing hydroperoxides and chelat-ing prooxidative metal ions [13 33] Epidemiological studiesconfirm that the incidence of oxidative stress-related condi-tions is lowered by the consumption of fruits and vegetablesrich in compounds possessing high antioxidant activity[18 34ndash37] Foods containing antioxidants and antioxidantnutrients play an important role in prevention

Chain breaking antioxidants able to scavenge radicalspecies are called primary antioxidants Secondary antioxi-dants are singlet oxygen quenchers peroxide decomposersthat yield nonradical species oxidative enzyme (eg lipoxy-genase) inhibitors UV radiation absorbers or compoundsthat act by metal chelating [38ndash40]

Natural antioxidants constitute the essential part in thecellrsquos defense mechanisms and they can be endogenous orexogenous

Endogenous antioxidants can be nonenzymatic such asglutathione alpha-lipoic acid coenzyme Q ferritin uricacid bilirubin metallothionein l-carnitine melatonin albu-min and antioxidant enzyme cofactors or enzymatic suchas superoxide dismutase catalase glutathione peroxidasesthioredoxins and peroxiredoxins Peroxiredoxins regulatecytokine-induced peroxide levels and mediate cell signaltransduction [41]

Enzymatic antioxidants at their turn are grouped withinthe primary and secondary defence systems The primarydefence is formed by three crucial enzymes capable ofpreventing the occurrence or neutralizing free radicals glu-tathione peroxidase which donates two electrons that reduceperoxides catalase that decomposes hydrogen peroxide intowater and molecular oxygen and superoxide dismutase thatturns superoxide anions into hydrogen peroxide [13 41] Thesecondary enzymatic defense comprises glutathione reduc-tase and glucose-6-phosphate dehydrogenase Glutathionereductase turns glutathione into its reduced form thus recy-cling it Glucose-6-phosphate reforms reductiveNADPH [4243] Although these two enzymes do not directly neutralizefree radicals they promote the endogenous antioxidantsrsquoactivity [13] It has been assessed that enzymatic antioxidantsact by decomposing free radicals and in this case damagingoxidative species are converted into hydrogen peroxide andwater while nonenzymatic antioxidants are mainly chainbreakers For instance it has been reported that tocopheroldisrupts a radical oxidation chain after five reactions [44]

Apart from the endogenous enzymatic and nonenzy-matic antioxidants previously discussed there are also exoge-nous diet-sourced antioxidants [40 43] represented bycarotenoids tocopherols vitamin D phenolic acids flavon-oids or ascorbic acid as well as high-molecular weight

Oxidative Medicine and Cellular Longevity 3

metabolites such as tannins For this second category thesource is represented by foodstuffs pharmaceuticals andfood supplements They are important in counteracting thereactive oxygenated species when the endogenous com-pounds are not able to ensure thorough protection [40 4345ndash47]

The intake of antioxidants from diet is always meantto counterpart the organismrsquos antioxidant defense Enzymicnatural antioxidants in food (superoxide dismutase glu-tathione peroxidase and catalase) can be inactivated duringprocessing

Particularly plant-sourced low-molecular weight antiox-idants such as glutathione and ascorbate are synthesizedwithin the chloroplast stroma and the cytosol in the presenceof reduced coenzymemolecules (NADPH) acting as the finalelectron source [48] These low-molecular weight antioxi-dants the cellrsquos redox buffer are involved in plant growth anddevelopment as they are able to modulate processes frommitosis and cell elongation to senescence and death [49 50]Commercial synthetic antioxidants with phenolic structuresuch as BHA BHT and TBHQ are added to foodstuffs toprevent lipid rancidity [51] and the difference in structuretransduces itself in antioxidant capacity difference [38]

Although review papers have been previously publishedon antioxidant activity in plants the present paper provides anovel way of gathering and also critically and comparativelypresenting these aspects The section devoted to criticaland conclusive aspects provides the reader with an originaldiscussion over extraction techniques and their comparisonas well as methodsrsquo performances (in a way that has notbeen systematized until now) with the following aspects con-cerned sample mechanism underlying the method workingparameters and detection

2 Antioxidant Extraction Procedures

Extraction techniques aim not only at extracting the activebiocompounds from the plant sample but also at impartingselectivity and optimizing sensitivity of the applied analyticalmethodology due to the increase of the concentration ofthe compound of interest The biocompound is more easilydetected and separated from other matrix components andthe assay becomes independent on the variable matrix char-acteristics [52]

Classical extraction techniques are based on the extrac-tive potential of various solvents using heating or mixingThe main shortcomings of conventional extraction are longextraction times the need for high purity expensive solventsevaporation of solvents in significant amounts reducedselectivity and finally the thermal decomposition in thecase of thermolabile substances [53] These problems canbe solved by nonconventional extraction techniques that aremainly regarded as ldquogreen techniquesrdquo as they use less toxicchemicals safer solvents which are characterized by betterenergy efficiency and minimum by-product amounts [54]

An important goal is represented by high extractionefficiency and efficacy Efficiency was defined as the yield ofextraction whereas efficacy represents the potential to inducebioactivity and the ability to produce an effect Therefore

a selection of the most appropriate extraction method isrequired in each case as it was proven that various techniquesapplied on the same plant material employing the samesolvent can lead to different extraction efficiencies Moreoverit has been confirmed that the most convenient method inthis regard requires standardization to attain reproducibility[55]

21 Conventional Techniques Soxhlet extraction was firstapplied only for lipid extraction but its use has been extendedfor extracting active principles The solvent is heated vapor-ized and condensed and extracts the interest compound(s)by contact with the sample-containing thimble When thesolvent in the extraction chamber reaches the overflow levelthe solution in the thimble-holder is aspirated by a siphonand returns in the distillation flask Significant extractionyields can be reached with a small solvent amount It can beapplied in batch at small scale but it can be converted into acontinuous extraction set-up on medium or large scale [56]

Maceration is applied to obtain essential oils and bioactivecompounds The plant material is ground to improve thesurface area The solvent is then added and allowed to standat ambient temperature for several days and the mixture issubject to frequent stirring until dissolution The dampedmaterial is then pressed and then the liquid is purified byfiltration or decantation [54 56]

Hydrodistillation (as water watersteam and direct steamdistillation) is applied to the extraction of bioactive com-pounds and essential oils from plants generally prior todehydration and does not imply the use of organic solvents[57] Hot water and steam isolate the bioactive compoundsfrom the plant tissue Consequently cool water condenses thevapor mix of water and oil The condensed mixture reachesthe separator where oil and biocompounds are isolatedfrom water [58] Hydrodistillation involves three main stepshydrodiffusion hydrolysis and thermal decomposition withthe risk being represented by the decay of thermolabilesubstances [54 56]

Infusions are prepared by shortly macerating the rawplant material with either cold or boiling water It is oftenmentioned that concentrated infusions are the result of amodified percolation or maceration procedure [56]

Percolation is a recognized procedure applied for thepreparation of tinctures and fluid extracts and makes useof a cone-shaped vessel opened at both ends (percolator)The solid material is moistened with an adequate amount ofthe appropriate solvent (menstruum) and left for about 4 hSolvent amount is necessary until the percolate representsabout three-quarters of the quantity corresponding to thefinal product The marc is then pressed and the eliminatedliquid is added to the percolate Solvent is again added to getthe required volume and the liquid mixture is clarified byfiltration or by decanting [56]

In the decoction process the crude plant material issubject to boiling in an appropriate water amount for awell-defined period followed by cooling and then strainingor filtering This approach is adequate for the extraction ofhydrosoluble thermostable components being popular forobtaining Ayurvedic extracts [56]


Cold pressing or expression consists in pressing or grindingfruits or seeds by using a press Oil release is possible dueto crushing or breaking of essential oil glands in the peelOlive peanut sunflower and citrus oils are obtained throughcold pressing which results in preserving flavor aroma andnutritional value

Aqueous Alcoholic Extraction by Fermentation The formedethanol enables extraction of the active principles from thematerial and also contributes to preserving the productrsquosqualities In Ayurveda this method is not standardized butwith progresses in the fermentation technology standardiza-tion would be of use for obtaining herbal drug extracts [56]

Vortex apparatus is commonly used to mix the interestplant sample with the dilutant It is applied for dissolutionnamely in aqueous environment and polar solvents ofsamples of plants to yield a fluid and homogeneous solutionsubject to analysis As in the case of other techniques likeshaking or sonication it can be followed by centrifugationwith use of the supernatant

22 Nonconventional (Modern) TechniquesSupercritical Fluid Extraction (SFE) Critical point wasdefined as the temperature and pressure above which dis-tinction between gas and liquid phases does not exist [59]In supercritical state gas and liquid properties are not indi-vidualized and supercritical fluid properties are tunable bytemperature and pressure modification Supercritical fluids(SCFs) possess both gas-like properties (diffusion viscosityand surface tension) and liquid-like density and solvationpower [60] The advantages are constituted by reduction ofextraction time when compared to conventional methodscomplete extraction by repeatable refluxes better selectivityin comparison to common liquid solvents due to solvationpower enhanced transport properties exhibited near thecritical point and hence high extraction yields [55] CO2 usedoes not imply high costs It operates at room temperatureso it is adequate for thermosensitive compounds smallersamples can be extracted comparedwith conventional solventextraction It is characterized by facility of coupling withchromatographic procedures and reutilization of SCF [5456] Disadvantagesmay be represented by polarity limitationsof carbon dioxide which can be minimized by the use oforganic solvents or inert gases (Ar) [56]

Solid Phase Microextraction (SPME) SPME employs a sor-bent which usually coats the surface of small fibers forthe isolation and concentration of target compounds fromthe sample and is applied to quantitative assay of analytes(essentially flavor compounds) in aqueous or gaseous phase

Microwave-Assisted Extraction (MAE) Microwaves interactwith the dipoles of polar and polarizable matrixes [61 62] Asthe forces of electric and magnetic field components swiftlymodify their orientation polar molecules also adopt orien-tation in the changing field direction and heat is generatedSo ionic conduction and dipole rotation are the mechanismsunderlying the conversion of electromagnetic energy to heat[54 63] The components of the sample absorb microwave

energy in conformity with their dielectric constants [64]When the plant material is found in a solvent transparentto microwaves the elevated vapour pressure causes ruptureof the cell wall of the substrate and frees the content intosolvent [55] Separation of solute molecules from the samplematrix at increased temperature and pressure is followed bydiffusion of solvent molecules across the sample matrix andtransfer of solute molecules from the sample matrix to thesolvent Microwave-assisted extraction is characterized byrapid heating to reach the temperature required for extractingbioactive principles [65] enhanced extraction yields verygood recovery and selectivity and minimum equipment sizeand solvent use [54 66]

Ultrasound-Assisted Extraction (UAE) Ultrasound waveswith frequencies comprised between 20 kHz and 100MHzinduce compression and expansion as they pass through theextractable plant matrix producing cavitation The energyproduced can promote the conversion of kinetic energy intothermal one inducing heating of the bubble contents Insolid plant samples ultrasounds enable compound leachingfrom the plant materials [67] The mechanism implies wavediffusion across the cell wall and rinsing of the cellrsquos contentafter breaking the walls [68] The physical chemical andmechanical forces induced by the collapse of bubbles resultin the disruption of membranes to enable the release ofextractable compounds and to facilitate penetration of thesolvent into cell material [69 70] Rapidity intensified masstransfer low solvent amounts high extraction yields andthroughput and reduced temperature gradients characterizethis technique [54] Nevertheless high ultrasound energymay result in cell membrane impairment due to free radicalgeneration but the deletions can be resealed by aggregationof lipid vesicles [71]

Pulsed-Electric Field (PEF) Extraction Living cells are sus-pended in an electric field and an applied potential crossesthe membraneThe electric potential induces molecule sepa-ration according to the molecular charge At values greaterthan 1V for the transmembrane potential the electrostaticrepulsion between the charged molecules results in poregeneration in the membrane and produces dramatic per-meability increase and yield is optimized [54 72] Theefficacy of the pulsed-electric field extraction depends onfield strength energy input pulse number temperature andmatrix characteristics [73] Pulsed-electric field extraction isalso appliable as pretreatment before carrying out traditionalextraction [74] It can be employed before grape skins macer-ation minimizing maceration time and imparting stability toanthocyanins and polyphenols [75]

Enzymatic Treatment Enzymes used are cellulase 120572-amylaseand pectinase which act by breaking the cellular wallwith subsequent hydrolysis of the structural polysaccharidesand lipids [76 77] Enzyme-assisted aqueous extractionand enzyme-assisted cold pressing are the main techniquesapplied [78] Enzyme amount particle size of the materialsolid to moisture ratio and hydrolysis time influence theperformances [79] Enzyme-assisted cold pressing is the


most proper for extracting biocompounds from oilseedsas nontoxic procedure which does not involve flammableliquids The oils extracted are richer in fatty acids andphosphorus than hexane-extracted ones [80] The enzyme-assisted aqueous extraction is environmental-friendly [81]In enzyme-assisted cold pressing biocatalysts hydrolyse theseed cell wall because the polysaccharide-protein colloidis not present as happens in the enzyme-assisted aqueousextraction [82]

Pressurized Liquid Extraction (PLE) PLE implies exertingan elevated pressure to the remaining liquid solvent abovethe boiling point High pressure values favor the extractionprocess which is easily prone to automation Pressurizedliquid extraction benefits much shorter extraction times andlower solvent requirements when compared to conventionalSoxhlet extraction At elevated temperatures and pressuresthe extraction performances are improved by the increasedanalyte solubility and mass transfer rate as well as by thediminished viscosity and low surface tension of solvents [5483]

3 Analytical Methods Applied toAntioxidant Content and AntioxidantCapacity Assessment in Plant ExtractsClassification and Principles

The investigation of performant analytical methods aimingto assess the antioxidant capacity in plants and plant extractsremains a constant goal and a series of classifications havebeen proposed Antioxidant measurement techniques wereclassified as methods based on the inhibition of low-densitylipoprotein oxidation estimation and the ones relying on thequantification of the free radical scavenging capacity [84]

Considering the mechanism underlying the antioxidantndashoxidant reaction the methods were also divided in hydrogenatom transfer (HAT) and single electron transfer (SET)techniques HAT-based methods measure the capacity of anantioxidant to trap free radicals by hydrogen donation whileSET methods rely on the one electron transfer reductiveability of an antioxidant compound versus a radical species[85] ORAC TRAP and chemiluminescence are hydrogenatom transfer-based methods whereas FRAP and CUPRACare single electron transfer methods [85] DPPH and TEACmethods were regarded as methods using both hydrogenand single electron transfer as the radicals in these casescan be scavenged by either electron reduction or radicalquenching that involves hydrogen transfer [85 86] DPPHscavenging TEAC assay ferric reducing antioxidant powerOH∙ scavenging the phosphomolybdenum method andbeta-carotene linoleate bleaching are applied in vitro whilethe lipid peroxidase catalase and glutathione peroxidaseactivity assays are techniques used in vivo [18] The analyticalresponse is also recorded as per reference to a standardantioxidant Trolox gallic acid ascorbic acid caffeic acid andso forth

The main chemical processes underlying antioxidantactivity assay (andashd) and lipid oxidation status evaluation (e)are detailed in Table 1 The latter are presented as they can

constitute the basis for antioxidant screening the assays canbe performed by following the prevention of peroxidationproducts generation in the presence of antioxidants mea-sured against a control The determinations may involvehydroperoxide conjugated diene or thiobarbituric acid reac-tive substances assay The antioxidant effect is expressedas percent of lipid peroxidation inhibition The group oftechniques involving low-density lipoprotein peroxidationinhibition by antioxidants is also classified as belongingto HAT methods as the reaction between the antioxidantand the peroxyl radicals (such as AAPH-initiated) involveshydrogen transfer

In Table 2 the methods are classified following the detec-tion mode with principle description for each technique

4 Significant Analytical Applications toPlant and Plant Extracts

41 Chromatography411 Planar Techniques Thin layer chromatograms of themethanolic extract of Bergia suffruticosa (used as bone andsore healer) proved antiradical activity by bleaching DPPH∙This free radical scavenging activity was assigned to the hightannin and phenolic amounts [90] A recently developedTLCndashDPPH∙ assay allowed for the swift detection of theantioxidant potential of nine out of ten tested polyphenols(except for apigenin 7-O-glucoside) present in five analysedplant species Hypericum perforatum L Matricaria recutitaLAchilleamillefoliumLThymus vulgaris L and Salvia offic-inalis L By LCndashMS the presence of compounds previouslyidentified by TLC was confirmed Four other compounds(caffeic acid and apigenin in St John wort and apigenin andapigenin 7-O-glucoside in sage) have been identified Theirpresence was not revealed by TLC and it has been statedthat their low level in the plant samples could be the reason[91]

Sonneratia caseolaris (astringent and antiseptic) extractswere tested for their antioxidant composition column chro-matography with a Diaion HP-20 column and successiveelution with methanol and acetone was first applied Thechlorophyll-free eluate was separated into 5 fractions byC18 column chromatography with methanol and acetonefor elution The methanol-eluted fraction containing DPPHpositive spots was then applied to a silica gel presqualenecolumn with n-hexane-acetonendashmethanol eluents resultingin eight fractions The first compound was obtained afterprecipitation from the fraction corresponding to the n-hexane-acetone 1 1 eluate One acetone-eluted fraction alsoyielded a precipitate which after washing with methanolresulted in the second compound The structures of theisolated compounds were assessed by one-dimensional andtwo-dimensional NMR and mass spectroscopy Moreoverboth showed positive (discolored) spots with a reddishpurple background on the thin layer chromatogram using a002 (wv) methanolic solution of DPPH as spray reagentLuteolin and luteolin-7-O-120573-glucoside were identified as thetwo bioactive antioxidant and anti-inflammatory compounds[92]


Table 1 The main chemical mechanisms underlying antioxidant activity (andashd) and lipid oxidation (e)(a) Hydrogen atom transfer (HAT)

Corresponding method of assay Mechanistic descriptionTRAP (Total Radical Trapping AntioxidantParameter) assayORAC (Oxygen Radical Absorbance Capacity)assayBeta carotenecrocin bleaching methodInhibition of induced low-density lipoproteinperoxidation assayChemiluminescence quenching due toluminol-derived radicals scavenging byantioxidants

ArOH + X∙ 997888rarr ArO∙ + XHAn antioxidant (eg phenolic compound ArOH) directly interacts with a freeradical (X∙) yielding a phenolic radical species derived from the antioxidant

molecule ArO∙ and a neutral species XH The antioxidant facility to follow HATmechanism is correlated with low bond-dissociation enthalpy [117] The presence ofdihydroxy functionality imparts good hydrogen donation abilities correlatable with

low bond-dissociation enthalpy values [118]

(b) Single electron transfer (SET)

Corresponding method of assay Mechanistic descriptionDMPD (NN-dimethyl-p-phenylenediamine)methodFRAP (ferric reducing antioxidant power) assayCUPRAC (cupric reducing antioxidant capacity)methodPFRAP (potassium ferricyanide reducing power)method

ArOH + X∙ 997888rarr ArOH∙+ + XminusSET assays rely on the capacity of an antioxidant ArOH to reduce the radical speciesX∙ by electron donation which is accompanied by the color change of the radicalsolution Low adiabatic ionization potentials are correlated with good electron

transfer abilities [117] Extended delocalization and electron conjugation result inlow ionization potentials [118] Also pH increase (deprotonation) favors electron

transfer(c) Mixed HAT and SET

Corresponding method Mechanistic description

DPPH (22-diphenyl-1-picrylhydrazyl) scavengingmethod

Hydrogen atom transfer and sequential proton-loss electron transfer (SPLET) alsodesignated proton-coupled electron transfer (PCET) [119 120] were both

confirmed as being thermodynamically favorableA SPLET mechanism involving the antioxidant ArOH and the radical ROO∙ was

represented as [121]ArOH 997888rarr ArOminus + H+

ArOminus + ROO∙ 997888rarr ArO∙ + ROOminus

ROOminus + H+ 997888rarr ROOHor coupling the second and third steps as [122]

TEAC (Trolox Equivalent Antioxidant Capacity)method

ArOH 997888rarr ArOminus + H+

ArOminus + X∙ + H+ 997888rarr ArO∙ + XHDuring the first step the phenolic antioxidant dissociates into its corresponding

anion ArOminus and a proton and subsequently the ions which resulted in the first stepreact with the free radical yielding a radical form of the phenolic antioxidant ArO∙

and a neutral molecule XH [122]Proton transfer can also occur following electron transfer as in single electron

transfer-proton transfer mechanism (SET-PT) [122]ArOH + X∙ 997888rarr ArOH∙+ + Xminus

ArOH∙+ 997888rarr ArO∙ + H+

During the first step a phenolic antioxidant reacts with the free radical X∙ yielding acationic radical ArOH∙+ derived from the phenolic compound and the anionic formof the radical Xminus This first step has been reported as thermodynamically significant

step In the second step the cationic radical form of the antioxidant ArOH∙+decomposes into a phenolic radical ArO∙ and a proton [122]

(d) Chelation power of antioxidants


Tetramethylmurexide (TMM) assayFree Cu(II) or Zn(II) which is not complexed by phenolics (eg tannins) is bound

to tetramethylmurexide (TMM) The complexation with TMM is assessed at482 nm for Cu(II) and at 462 nm for Zn(II) [123]


(d) Continued


Ferrozine assay Free Fe(II) that is not complexed by phenolics (eg tannins) is bound to ferrozineThe complexation of divalent iron with ferrozine is assessed at 562 nm [123](e) Oxidation of lipids


Peroxide value assessment Lipid autoxidation results in generation of hydroperoxides determinediodometrically or colorimetrically [119]

Conjugated diene assay Fatty acids autoxidation yields conjugated dienes assessed by UV absorbance at234 nm [119]

Anisidine assaySecondary lipid oxidation yields p-anisidine-reactive aldehydes (alkenals

alkadienals and malondialdehyde) the resulted Schiff base being determined at350 nm [119]

Thiobarbituric acid reactive substancesMalondialdehyde and unsaturated aldehydes (alkenals and alkadienals) react withthiobarbituric acid the reaction product is determined photocolorimetrically at

532 nm [119]

High performance thin layer chromatography combinedwith densitometry was applied for caffeic acid quantitationin Plantago lanceolata The best eluent composition wasdetermined in first step of development the mobile phasecontained hexane diisopropyl ether and formic acid 90(60 40 05) vv In the second and third steps a mix-ture of hexane diisopropyl ether dichloromethane formicacid 90 and propan-2-ol (60 40 20 10 01) vv wasemployed The application of this HPTLC technique witharea measurements at 320 nm led to a caffeic acid amountequal to 993 120583gg of dried plant with RSD of 319[93]

HPTLC [94] was also used for the screening and quan-titation of phytochemicals present in Scoparia dulcis knownfor many health benefits [95] (see Table 3) After applicationof the anisaldehyde-sulphuric acid visualization reagent thespotted plate was exposed to UV radiation (254 and 366 nm)and multicolored bands at various intensities were noticedOn the TLC plates the presence of phenolics (flavonoids) andterpenoids has been revealed [94]

The antioxidant capacity of essential oils obtained fromthe seed and whole plant of Coriandrum sativum wasassessed and HPTLC was applied to assess significant phy-tomarkers The in vitro determined antioxidant capacity wasgreater than the one corresponding to various extracts ofthis Ayurvedic plant The chromatographic profile showedlinalool and geranyl acetate as main phytoconstituents of theanalysed samples The HPTLC system was based on a TLCscanner an autosampler connected to a nitrogen cylindera UV scanner and visualizer The limits of detection andquantification were obtained as 04 and 12 ngmL for linalooland 06 and 14 ngmL for geranyl acetate revealing sensitiv-ity The precision was proven by the result of minimum sixreplicate analyses with a coefficient of variability of 007[96]

412 Column Techniques

(1) Gas Chromatography The composition of various extractsofMerremia borneensiswas assessed by GC-MS showing thepresence of flavonoids terpenoids alkaloids and glycosides

in the analysed organic crude extracts [97] The qualitativeanalysis of bioactive compounds present in Datura metel wasperformed in crude extracts by GCMS revealing abundancyof high-molecular weight components such as polyphenolsflavonoids triterpenoids and hydrocarbons The phenoliclevel was expressed as gallic acid equivalents with chloroformhaving the best extractive potential followed by methanolbutanol ethyl acetate and hexane It has been concludedthat the chloroform crude extract had the highest phenolicsamount and its potential as antibiotic has been stated [98]

Essential oils from the aerial parts of Ajuga bracteosaand Lavandula dentata obtained by hydrodistillation wereanalysed by GC and GCMS 47 and 48 biocomponents wereidentified for the two analysed plants respectively The oilscontained high amounts of oxygenated monoterpenes (34 to51) Borneol (208) and hexadecanoic acid (160) werethemajor compounds present in the oil ofA bracteosa whichalso contained aliphatic acids (303) Camphor (124)trans-pinocarveol (75) and 120573-eudesmol (71) were preva-lent in Lavandula dentata oil The antioxidant activity of theoil extracts was confirmed by DPPH∙ scavenging assay [99]

(2) Liquid Chromatography The rapid and resolution-highdetermination of six bioactive flavonoids present in thepericarp ofCitri reticulatahas been performed by liquid chro-matographyelectrospray ionization coupled with mass spec-trometry The chromatographic system used a C18 columnand a 01 formic acidacetonitrile mobile phase with a gra-dient elution Naringin hesperidin nobiletin 356783101584041015840-heptamethoxyflavone tangeritin and 5-hydroxy-6783101584041015840-pentamethoxyflavone were assessed by the above-mentionedchromatographic technique and were also investigated fortheir antiproliferative activities by Cell Counting Kit-8Assay In the cultivars analysed hesperidin presented thehighest content ranging from 50137 to 100525mgg Thelevels of nobiletin tangeritin and 5-hydroxy-6783101584041015840-pentamethoxyflavone were higher in the peel of Citrusreticulata ldquoChachirdquo than in other cultivars With respect tothe antiproliferative activity against A549 and HepG2 cells5-hydroxy-6783101584041015840-pentamethoxyflavone has been provento be the most effective [100]


Table 2 Illustration of the main principles and detection mechanisms in antioxidant activity measurement

Method for antioxidantcapacity assay Principles underlying the analytical techniques Detection modes Ref

Chromatographic techniques

Thin layer chromatography

The stationary phase is a thin layer of silica gelaluminium oxide or cellulose which covers asupport of glass plastic or aluminium foil The

mobile phase moves by capillarity

Migration of analytes takes place atdifferent rates due to various repartition

coefficients[91]

High performance thinlayer chromatography

It relies on the same principle as conventionalTLC but uses a stationary phase with smaller

particle size

Separation performed with improvedresolution versus TLC [93 94]

Gas chromatography Separation is based on the repartition between aliquid stationary phase and a gas mobile phase

Flame ionization thermal conductivityor mass spectrometry detection [124]

Liquid chromatography Separation is based on the repartition between asolid stationary phase and a liquid mobile phase

Mass spectrometry or electrochemicaldetection [106]

High performance liquidchromatography

Separation is based on the repartition between asolid stationary phase and a liquid mobile phasewith distinct polarities at high flow rate and

pressure of the mobile phase

UV-VIS (diode array) fluorescence massspectrometry or electrochemical

detection[108]

Spectrometric techniquesDPPH (22-diphenyl-1-picrylhydrazyl) scavengingmethod

Antioxidant reaction with the nitrogenatedradical followed by absorbance diminution at

515ndash518 nmPhotocolorimetry [125 126]

TEAC (Trolox EquivalentAntioxidant Capacity)method

Antioxidant reaction with ABTS∙+ (221015840-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid

cation radical) generated by K2S2O8 followed byblue solution absorbance diminution at 734 nm

Photocolorimetry [127]

DMPD (NN-dimethyl-p-phenylenediamine)method

Reduction of DMPD∙+ by antioxidants in thepresence of FeCl3 with subsequent absorbance

decrease at 505 nmPhotocolorimetry [128]

FRAP (ferric reducingantioxidant power) method

Reduction of the Fe3+-TPTZ(246-tripyridyl-s-triazine) complex by sampleantioxidants with absorbance taken at 593 nm


PFRAP (potassiumferricyanide reducingpower) method

Reduction of potassium ferricyanide byantioxidants yielding potassium ferrocyanideThe latter reacts with ferric trichloride and theresulted ferric ferrocyanide blue colored complexis measured at maximum absorbance of 700 nm


CUPRAC (cupric reducingantioxidant capacity)method

Cu(II)-neocuproine complex reduction to Cu(I) ndashbis (neocuproine) chelate with absorbance

recorded at 450 nmPhotocolorimetry [131 132]

Phosphomolybdenumassay

Mo (VI) is reduced Mo (V) by the antioxidants inthe sample with generation of a green

phosphateMo (V) complex at acidic pHdetermined at 695 nm


Lipid peroxidation activityassay

Antioxidants delay lipid hydroperoxidegeneration caused by lipoxygenase Theabsorbance is measured at 234 nm

UV absorbance [106 134]

Antioxidants delay radical-induced malonyldialdehyde generation as decomposition productof endoperoxides of unsaturated fatty acids in thepresence of thiobarbituric acid The absorbance is

measured at 535 nm

Photocolorimetry [106 135]

Antioxidants delay conjugated dienes generationas a result of peroxidation of lipid components

The absorbance is measured at 234 nmUV absorbance [85]


Table 2 Continued


Superoxide radicalscavenging activity assay

Antioxidants are subject to reaction with asubstrate solution containing xanthine sodiumsalt and 2-(4-iodophenyl)-3-(4-nitrophenol)-5-phenyltetrazolium chloride Xanthine oxidase isused as biocatalyst and the absorbance increase

was monitored at 505 nm


Superoxide anions are generated in a solutioncontaining nitroblue tetrazolium NADH and

phenazine methosulfate The absorbance taken at560 nm decreases in the presence of antioxidantspointing towards superoxide anion scavenging

activity


Beta carotene bleachingmethod

Linoleic acid is oxidized by reactive oxygenspecies The generated oxidation products such aslipid peroxyl radicals initiate 120573-carotene oxidation

and consequently its decolorizationAntioxidants delay the discoloration rate with

absorbance measured at 434 nm


Xanthine oxidaseinhibition assay

Xanthine is used as substrate that yields uric acidas product of XOD-catalyzed reaction

Allopurinol is used as xanthine oxidase inhibitorAbsorbance is measured at 293 nm


Superoxide dismutasemethod

It is assessed in an erythrocyte lysate in thepresence of pyrogallol The enzyme inhibits theautooxidation of the hydroxylated compound

with absorbance read at 420 nm


Catalase activity assayIt is measured in an erythrocyte lysate in the

presence of H2O2 The rate of H2O2decomposition is assessed at 240 nm


Ferrous ion chelatingactivity assay

Antioxidants react with ferrous salt (eg FeCl2)Ferrozine as Fe(II) chelator yields a violet complexwith absorbance read at 562 nmThe reaction ishindered in the presence of antioxidants that actby chelation and the result is a decrease of thecolor of the ferrozine-Fe2+ complex as chelatorsother than ferrozine act as competing agents for

the metal ion


ORAC (Oxygen RadicalAbsorbance Capacity) assay

Antioxidants scavenge the peroxyl radicalsinduced by 221015840-azobis-(2-amidino-propane)

dihydrochloride (AAPH) decomposition slowingthe fluorescent decay of fluorescein or

phycoerythrin

Fluorimetry [145ndash147]

HORAC (Hydroxyl RadicalAntioxidant Capacity)assay

Antioxidants quench OH radicals formed in aFenton-like system Fluorimetry [148]

TRAP (Total RadicalTrapping AntioxidantParameter) assay

The rate of peroxyl radical generation by221015840-diazobis-2-amidinopropane dihydrochloride(ABAP) is quantified through the fluorescencediminution of the protein R-phycoerythrin

Fluorescence [149 150]

Horseradish peroxidase-luminol-hydrogen peroxidechemiluminescent assay

Horseradish peroxidase catalyses luminoloxidation by H2O2 with light emission Light

emission is quenched by antioxidantsChemiluminescence [151]

Electrochemical techniques

Cyclic voltammetry The potential is linearly swept in a triangularwaveform

The analytical signal is represented by theintensity of the cathodicanodic peak [152 153]

Differential pulsevoltammetry

Potential voltage pulses are superimposed on thepotential scan which is performed linearly or

stairstep-wise

First current sampling before applyingthe pulse and the second towards the end

of the pulse period[154 155]


Table 2 Continued


Square-wave voltammetry A square wave is superimposed on the potentialstaircase sweep

Current intensity recorded at the end ofeach potential change [155 156]

AmperometryThe potential of the working electrode ismaintained at a constant value versus the

reference electrode

Current intensity generated by theoxidationreduction of an electroactive

analyte[157]

Biamperometry

The reaction of the antioxidant with the oxidizedform of a reversible indicating redox couple in anelectrochemical cell containing two identical

electrodes

The current flowing between twoidentical working electrodes at a constant

small applied potential difference[158ndash160]

Potentiometry

The analytical signal represented by the potentialchange is the result of the variation of an ionic

species concentration The antioxidants react withthe oxidized form of a redox couple altering theconcentration ratio between the oxidized form

and the reduced form

Potential change after reaction ofantioxidants with an indicating redox

couple[161]

Chromatography followed by electrochemical detectionproved its viability in the assessment of onion (Alliumcepa) parsley (Petroselinum crispum) roots and leaves cel-ery (Apium graveolens) roots and leaves of dill (Anethumgraveolens) extracts relying on the antioxidant compoundsrsquospecific oxidation It has been confirmed that the methodis characterized by sensitivity and simplicity of detectionsince no additional instrumentation (reagent pump or sec-ondary detector) is necessary In comparison to the resultsobtained using reversed-phase chromatographic separationwith online postcolumnDPPH scavenging detection HPLC-ED provided much richer chromatographic profiling ofcelery leaves extracts At elevated electrooxidation potentialvalues higher than 700mV compounds that are electroactivecontribute to HPLC-ED detection but are missed in thepostcolumn DPPH scavenging [101]

The HPLC chromatograms of Carissa opaca variousfractions proved the presence of orientin isoquercetinmyricetin and apigenin endowed with antioxidant activityThe antibacterial antitumoral and anticarcinogenic potentialof these flavonoid-rich fractions of Carissa opaca has alsobeen confirmed in this study [102]

Eleven Algerian medicinal plants were subject to analysisfor their antioxidant capacity and phenolic profileTheHPLCresults revealed that the hydroxycinnamic acid derivativeswere the predominant phenolics of the extracts endowedwithbest antioxidant activity (Anthemis arvensis and Artemisiacampestris) Nevertheless it was stated that in this casethe correlation between the antioxidant activity of analysedextracts and their phenolic composition is very difficultto be described by statistical tools It was assumed thatthis difficulty may result not only from the fact that totalphenolics do not include all the antioxidants but also from thesynergism and structure interaction among the antioxidantswhich does not always involve concentration influence Forinstance samples such asArtemisia arborescens andOudneyaafricana with close concentration values of total phenolicsexhibited varying antioxidant activity On the whole theantioxidant activity and flavonoids concentration did not

correlate significantly in comparison to hydroxycinnamicacids and hydroxybenzoic acids Artemisia campestris wasassessed as the most powerful inhibitor of radical-inducedred blood cells hemolysis more active than caffeic acid morethan three times more active than ascorbic acid and twotimes more active than 120572-tocopherol The UV spectra wereobtained in the range of 220ndash600 nm and the amounts ofphenolics in the extracts were assessed from the calibrationcurves developed at the absorption maxima of each phenolicclass [103]

Methanolic extracts of the leaves of Rosmarinus officinaliswere assessed by HPLC for their radical scavenging antioxi-dant activities The identified compounds namely carnosolcarnosic acid and rosmarinic acid varied as depending onthe geographical regions and season The chromatographicsystem involved a C18 column and a mobile phase composedof methanol and acetic acidacetonitrile with gradient elu-tionThe highest content of carnosic acid was obtained in thesamples harvested from Mersin the highest rosmarinic acidlevel was assigned to Canakkale-originating samples (140ndash304mgg) For all extracts the carnosol content ranged from54 to 255mgg and the carnosic acid level ranged from 38to 1158mgg [104]

The phenolic ingredients in samples of 24 cereal grainswere analysed by HPLC relying on the peak area of max-imum absorption wavelength The chromatographic setupwas comprised of a C18 column a mobile phase with anelution gradient between solution A (acetic acid-water andmethanol) and solution B (methanol and acetic acid-watersolution) and a photodiode array detector Gallic acidkaempferol quercetin galangin and cyanidin 3-glucosidewere found in high amounts in these cereals [105]

HPLC was also applied along with LC-MS for theestimation of polyphenolic compounds from bitter cuminThe amount of phenolic compounds (120583gg dry weight) wasestimated by comparing the peak areas (at 254 nm) of thesamples with that of standards proving the prevalence ofcaffeic acid 5000 120583gg dry weight [106]


Table 3 Significant examples of total antioxidant capacity assessment in plants

Number Analysed products(extracts) Compounds determined Applied analytical

techniqueHealth benefits as theyappear in the cited studies Ref

(1)

Leaves from cherry treepeach tree plum tree olivetree pear tree apple treepistachio and chestnut

(i) Total phenols(ii) Nonflavonoids phenol(iii) Total antioxidantcapacity

(i) DPPH assay(ii) FRAP assay

Used in pharmaceuticalpurposes and also act asnatural pesticides andbeverage ingredients

[162]

(2) Leaf extracts from six Vitisvinifera L varieties

(i) Total phenols(ii) Flavonoidsnonflavonoids andflavanols(iii) Total antioxidantcapacity

(i) HPLC(ii) DPPH assay(iii) FRAP assay

Antimicrobial activity [163]

(3)Tropical herbsMomordicacharantia Centella asiatica

andMorinda citrifolia

(i) Catechin(ii) Total antioxidantcapacity


Inhibitors of pancreaticlipase activity [164]

(4)Edible and medicinal

Acacia albida organs (leavesand bark)

(i) Polyphenols(ii) Total antioxidantcapacity

(i) HPLC(ii) DPPH assay(iii) ABTS assay

Traditionally used to treatcolds flu fever toothdecay vomiting diarrheaurinary disorders malariaand inflammation

[165]

(5) Citrus fruits Total antioxidant capacity

(i) HPLC free radicalscavenging detection(ii) DPPH assay(iii) ABTS assay

[166]

(6) Salvia sp and Plantago sp(i) Total phenolic content(ii) Total antioxidantcapacity

(i) UV-Vis fingerprint(ii) DPPH assay

Helpful in preventingdifferent diseases [167]

(7) Ajuga iva (leaf extracts)

(i) Total phenolic content(ii) Total flavonoids(iii) Total antioxidantcapacity


Diuretic cardiac tonic andhypoglycemic [168]

(8) Filipendula vulgaris(i) Total phenolic content(ii) Total antioxidantcapacity

(i) DPPH assay(ii) ABTS assay

(i) Antibacterial activity(ii) Fights againstinflammatory diseasesrheumatoid arthritis andgout

[169]

(9) Asphodelus aestivus Brot Total antioxidant capacity(i) FRAP assay(ii) DPPH assay(iii) ABTS assay

(i) Are used againsthemorrhoids nephritisburns and wounds(ii) Gastroprotective effectagainst ethanol-inducedlesions

[170]

(10) Melia azedarach(Chinaberry) (bark extract) Total antioxidant capacity DPPH assay Antimicrobial agents in

various infectious diseases [171]

(11) Bitter bean Parkia speciosa

(i) Total phenolicconstituents(ii) Total antioxidantcapacity

(i) HPLC(ii) Folin-Ciocalteu method(iii) DPPH assay(iv) ABTS assay

(i) Antibacterial effects onkidney ureter and urinarybladder(ii) Diuretic and relaxingproperties(iii) Seed extracts werereported to possesshypoglycemic anticancerand antiangiogenicactivities

[172]

(12) Brassica oleracea L

(i) Glucosinolates(ii) Total phenolicconstituents(iii) Ascorbic acid(iv) Total antioxidantcapacity

(i) HPLC(ii) Folin-Ciocalteu method(iii) DPPH assay

(i) Neutralizes carcinogens(ii) Attenuates cancer celldivision(iii) Accelerates the atrophyof cancer cells withdamaged DNA

[116]


Table 3 Continued



(13) Grape pomace seed andskin extracts

(i) Total phenols(ii) Total anthocyanins(iii) Total tannins(iv) Total antioxidantcapacity

(i) HPLC MS(ii) DPPH assay(iii) TEAC assay(iv) ABTS assay(v) Folin-Ciocalteu method

Limit the oxidation ofnucleic acids proteins andlipids which may initiatedegenerative diseases

[173]

(14)

Diplotaxis simplex(Brassicaceae)

(flower leaf and stemextracts)

(i) Total phenolsflavonoids andproanthocyanidins(ii) Total antioxidantcapacity

ORAC assay Anti-inflammatory activity [174]

(15) Cereal grains (24 cerealgrains from China)


(i) FRAP assay(ii) TEAC assay(iii) HPLC(iv) Folin-Ciocalteumethod

Reduces the risk ofcardiovascular diseases andreduces type II diabetesischemic stroke and somecancers

[105]

(16) Some cereals and legumes


(i) Folin-Ciocalteu method(ii) DPPH assay(iii) FRAP assay

(i) Reduces the incidence ofage-related chronic diseases(ii) Reduces heart diseasesand some types of cancer

[175]

(17)Clusia fluminensis Planch

amp Triana(i) Flavonoids content(ii) Total antioxidantcapacity

(i) Photometricassay based on aluminumchloride complexformation(ii) DPPH assay

(i) Antifungicidal activity(ii) Protection againstcardiovascular diseases

[176]

(18) Bitter cumin (Cuminumnigrum L)


(i) HPLC(ii) DPPH assay

(i) Antibacterial activity(ii) Reduces risk of cancerand cardiovascular diseases

[106]

(19)Essential oils of

Cynanchum chinense andLigustrum compactum

Total antioxidant capacity (i) DPPH assay(ii) ABTS assay

(i) Anticonvulsant(ii) Antitumor(iii) Antimicrobial

[177]

(20)Caspicum annum Lgrossum sendt

Rosmarinus officinalis


(i) Folin-Ciocalteu method(ii) ABTS assay [178]

(21) Diospyros bipindensis(Gurke)

(i) Plumbagincanaliculatin ismailinbetulinic acid and4-hydroxy-5-methyl-coumarin(ii) Total antioxidantcapacity

(i) HPLC NMR and MSanalyses(ii) DPPH assay(iii) ABTS assay(iv) ORAC assay

Anti-inflammatory andantimicrobial activities [179]

(22) Carissa opaca fruits Total flavonoids content HPLC(i) Antibacterial activity(ii) Anticancer activity(iii) Antitumoral activity

[102]

(23) Artemisia capillaris herba


(i) HPLC MS(ii) DPPH assay(iii) 120573-carotene bleachingmethod

(i) Cholagogic antipyreticanti-inflammatory anddiuretic in jaundice(ii) Used againstinflammation of the liverand cholecyst

[114]

(24)Lantana camara (variousparts leaf root fruit and

flower)


(i) DPPH assay(ii) Folin-Ciocalteu method

Used against itches cutsulcers rheumatismeczema malaria tetanusand bilious fever

[180]


Table 3 Continued



(25) Grape extracts

(i) Total phenolicconstituents(ii) Total anthocyanins(iii) Tannins(iv) Total antioxidantcapacity

(i) Folin-Ciocalteu method(ii) Binding withpolyvinylpyrrolidone(iii) ABTS assay

[181]

(26) Scutellaria baicalensis radix Total antioxidant capacity DPPH assay

Used in hepatitis andinflammation of therespiratory andgastrointestinal tract

[182]

(27) Lycium species



Diuretic antipyretic tonicaphrodisiac hypnotichepatoprotective andemmenagogic

[107]

(28)Dried fruits consumed inAlgeria (prunes apricots

figs and raisins)

(i) Total phenolicconstituents(ii) Total anthocyanins(iii) Total antioxidantcapacity

(i) Folin-Ciocalteu method(ii) DPPH assay(iii) Phosphomolybdenummethod

Reduce the risk of cancerand heart disease [183]

(29)Rubus grandifolius Lowe(leaves flowers and

berries)

(i) Total antioxidantcapacity(ii) Total phenolicconstituents

(i) DPPH assay(i) ABTS assay(iii) FRAP assay(iv) HPLC

Acts as astringent and asremedy for diabetes and isdepurative and diuretic andrelieves sore throat

[184]

(30) Red pitaya (Hylocereuspolyrhizus) seed

(i) Total antioxidantcapacity(ii) Total phenolicconstituents(iii) Flavonoids content

(i) DPPH assay(ii) Folin-Ciocalteu method(iii) HPLC

[185]

(31)Cornelian cherry Japanesepersimmon and cherry

laurel

(i) Total phenolic content(ii) Total flavonoids content(iii) Total antioxidantcapacity

(i) Folin-Ciocalteu method(ii) DPPH assay(iii) FRAP assay(iv) CUPRAC assay

Able to provide preventionof diseases [186]

(32) Inula crithmoides L(i) Total phenolic content(ii) Total antioxidantcapacity

(i) Folin-Ciocalteu method(ii) DPPH assay

Antibacterial antifungaland cytotoxic [187]

(33) Lycium intricatum Boiss(i) Total phenolic content(ii) Total antioxidantcapacity

(i) Folin-Ciocalteu method(ii) HPLC(iii) DPPH assay(iv) ABTS assay(v) FRAP assay

Decreases the risk ofdiseases such as cancerneurodegenerativedisorders andcardiovascular diseases

[188]

(34)Millingtonia hortensis Linnparts (leaves stem root

and flower)

(i) Total phenolic content(ii) Total antioxidantcapacity


Reduces risks of diabetescancer and cardiovasculardiseases

[189]

(35) Ononis natrix(i) Total phenolic content(ii) Total antioxidantcapacity

(i) Folin-Ciocalteu method(ii) DPPH assay Antimicrobial activities [190]

(36) Citrus grandis Osbeck Total antioxidant capacity DPPH assay [191]

(37)Sorbus torminalis (L)

Crantz (wild service tree)fruits


(i) Folin-Ciocalteu method(ii) ABTS assay(iii) DPPH assay

Used in treatment ofcardiac diseases andAlzheimerrsquos disease

[192]


Table 3 Continued



(38) Rosmarinus officinalis(i) Total phenolic content(ii) Total antioxidantcapacity

(i) HPLC(ii) DPPH assay(iii) TEAC assay

[104]

(39) Sapindus mukorossi Gaertn(i) Total phenolic content(ii) Total antioxidantcapacity


Fights against heart diseaseaging diabetes mellitusand cancer

[193]

(40) 11 medicinal Algerian plants(i) Total phenolic content(ii) Total antioxidantcapacity

(i) Folin-Ciocalteu method(ii) HPLC(iii) ABTS assay(iv) TEAC assay

Antitumoral anticanceranalgesic diureticanalgesic and so forth

[103]

(41) Six Teucrium arduini Lpopulations


(i) Folin-Ciocalteu method(ii) FRAP assay(iii) ABTS assay(iv) DPPH assay

Hypoglycemic antipyreticantiulcerative andantibacterial

[194]

(42) Vitex agnus-castus (VitexAC) Total antioxidant capacity

(i) ABTS assay(ii) DPPH assay(iii) FRAP assay(iv) CUPRAC assay

Cytotoxic activities againstvarious types of cancer cells [195]

(43) Andrographis paniculata

(i) Total antioxidantcapacity(ii) Total phenolic content(iii) Total andrographolidesconcentration

(i) DPPH assay(ii) FRAP assay(iii) CUPRAC assay(iv) HPLC-DAD(v) LC-MSMS(vi) GC-MS

(i) Treats dyspepsiainfluenza dysenterymalaria and respiratoryinfections(ii) Antidote for snakebitesand poisonous stings(iii) Active in cytotoxicitytests against cancer celllines

[111]

(44)

Hypericum perforatum LMatricaria recutita LAchillea millefolium LThymus vulgaris L and

Salvia officinalis L

(i) Total antioxidantcapacity(ii) Total phenolic content

(i) Thin layerchromatography(ii) LC MS(iii) DPPH assay

Anti-inflammatoryantiviral antimicrobialantiallergic anticancerantiulcer and antidiarrheal

[91]

(45) Celastrus paniculatusWilld Total antioxidant capacity

(i) DPPH assay(ii) FRAP assay(iii) TEAC assay(iv) GC MS

Calmant [196]

(46) Cerrado Brazilian fruits(i) Total phenolic content(ii) Total antioxidantcapacity

(i) Folin-Ciocalteu method(ii) ABTS assay

Chemopreventive effects [197]

(47) Buckwheat (FagopyrumesculentumMoench)


(i) HPLC(ii) DPPH assay [198]

(48)Green and black tea

infusions herbal infusionsand fresh fruit extracts

Total antioxidant capacity Potentiometric and flowinjection [161]

(49) Cocoa beans (rawpreroasted and roasted)


(i) Folin-Ciocalteu method(ii) DPPH assay(iii) ABTS assay

[199]

(50) Rapeseed and its products(i) Total phenolic content(ii) Total antioxidantcapacity

(i) Silvernanoparticle-based method(ii) Folin-Ciocalteu method(iii) DPPH assay(iv) FRAP assay

[200]


Table 3 Continued



(51)Edible plants (broccolicauliflower strawberrytomato potato and corn)

Total antioxidant capacity Cyclic voltammetry [201]

(52) Herb extracts from theLabiatae family Total antioxidant capacity (i) DPPH assay

(ii) AmperometricAntioxidant in foodindustry [202]

(53)

Indian mushrooms(Agaricus bisporus

Hypsizygus ulmarius andCalocybe indica)


(i) DPPH assay(ii) FRAP assay(iii) Folin-Ciocalteumethod(iv) Cyclic voltammetry

Provides health benefitsand protection againstdegenerative diseases

[203]

(54)

Three types of algaeSpirulina subsalsa and

Selenastrum capricornutum(both cultivated) and(powdered) Spirulina

maxima

Total antioxidant capacity

(i) Amperometric using theenzymatic biosensor withsuperoxide dismutase(ii) Cyclic voltammetry

Antiaging potential [204]

(55)

Buckwheat sprouts (rootsobtained from dark- and

light-grown) Total antioxidant capacity (i) TEAC assay(ii) Cyclic voltammetry [205]

(56) Tea infusions(i) Total phenolic content(ii) Total antioxidantcapacity

(i) HPLC(ii) Cyclic voltammetry

Reduce blood glucose level [206]

(57) Coriandrum sativum Antioxidant terpenes HPTLC

digestiveanti-inflammatoryantimicrobialhypolipidemicantimutagenic andanticarcinogenic

[96]

(58) Scoparia dulcis Flavonoids and terpenoids HPTLC

Antibacterial antifungalantiherpeticanti-inflammatoryantiseptic antispasmodicantiviral cytotoxicemmenagogic emollientfebrifuge and hypotensive

[95]

(59) Acacia confusa(i) Total phenolic content(ii) Total antioxidantcapacity


Used for wound healingand antiblood stasis [207]

(60) Teas and herbal infusions(i) Total phenolic content(ii) Total antioxidantcapacity

(i) Folin-Ciocalteu method(ii) DPPH assay(iii) FRAP assay(iv) ABTS assay(v) Polarographic

[208]

(61) Extra virgin oils Total phenolic content Voltammetric [209]

(62) Selected wines(i) Total phenolic content(ii) Total antioxidantcapacity

(i) Folin-Ciocalteu method(ii) DPPH assay(iii) Differential pulsevoltammetry

[210]

(63)

Fruits (raspberrystrawberry and berry fruit)

and vegetables (carrottomato and rhubarb)

Antioxidant capacity Differential pulsevoltammetry [211]


The profile and quantitative analysis of compoundspresent in Lycium species was performed using HPLC withdiode array detection p-coumaric acid chlorogenic acid andrutin were identified by their retention times and UV spectraversus those of the standards Other benzoic and hydroxycin-namic acids flavonoids and anthocyanin derivatives wereidentified by UV spectra and quantified by using gallic acidp-coumaric acid rutin and cyanidin-3-glycoside respec-tively as standards Phenolic acid derivatives confirmedtheir prevalence and presence in the highest amounts in allanalysed extracts Butanolic extracts of Lycium barbarum andLycium ruthenicum were characterized by the highest levelof benzoic and hydroxycinnamic acid derivatives which wasin accordance with the most enhanced antiradical activity ofthese extracts [107]

HPLC with diode array detection and ion trap MSwas applied to assess dose response and metabolism ofanthocyanins present in strawberry Pelargonidin 3-glucosidewas the main anthocyanin present in strawberry andthis anthocyanin and three of its metabolites (detected asmonoglucuronides) were excreted and assessed in urineafter ingestion One prevalent monoglucuronide form wasdetected in urine in masses 10-fold higher than the other twomonoglucuronide forms It was assessed that anthocyaninsfrom strawberries present a linear dose response over rangesof 15ndash60mmol The 24 h urinary recoveries were muchmore elevated than those reported for most of the otheranthocyanins and it has been concluded that pelargonidin-based anthocyanins may be more efficiently absorbed thanother anthocyanins [108]

18 phenolic compounds have been analysed by HPLC-MS in harvested and commercial 50methanolic extracts ofOcimum basilicum In the extracts obtained from harvestedsamples rutin (665052mg100 g dried plant) and caftaricacid (1595322mg100 g dried plant) were determined in thelargest amount Commercial samples contained hydroxycin-namic acid derivates dihydroxybenzoic acid flavonols andflavonoid glycosides [109]

The determination of rosmarinic acid content of Salviamaxima and Salvia verdewas carried out byHPLCMethanolwas employed for the extraction of the Salvia samples thenfiltration (on a 045mm PTFE filter) was performed beforeinjection in the LC-DAD-ESIMS setup The mobile phasewas comprised of 01 (vv) formic acid and acetonitrile withthe application of linear gradient The content of phenolicsin the analysed samples was assessed through interpolationof the peak area using the calibration curve developed perreference to the rosmarinic acid peak and retention timeThe results obtained as rosmarinic acid equivalent contentranged from 103plusmn 2 120583gg freshmaterial for Smaxima to 174plusmn2 120583gg freshmaterial for Salvia verde with a limit of detectionof 34 times 10minus7mol Lminus1 [110]

The application of a series of chromatographic techniques(HPLC-DAD LC-MSMS and GC-MS) led to the successfuldetection of antioxidant purine alkaloids (caffeine theo-bromine and theophylline) and indole alkaloids (harmineharmane harmol yohimbine brucine and strychnine) inAndrographis paniculata and in dietary supplements con-taining this plant This Ayurveda plant is used for healing

purposes (see Table 2) hence the interest in structure andpotential toxicity elucidation Purine and indole alkaloidsassessment byHPLC-DAD LC-MSMS andGC-MS showedlower concentration of these components in roots of 5071 plusmn036mgg dm in comparison to the leaves of 7871 plusmn048mgg dm In addition three bioactive diterpenoids weredetermined by HPLC-DAD and GC-MS methods with goodselectivity accuracy (recovery gt 915) and precision (RSDlt 50) [111]

The analysis of phenolic synthetic antioxidants BHABHT and TBHQ in edible oils was carried out by HPLCwith UV-VIS detection at 280 nm on the basis of peak arearatios The mobile phase was composed of methanol and001mol Lminus1 monosodium phosphate with gradient elutionBHA content ranged between 201 120583g gminus1 in rapeseed oil and559 120583g gminus1 in sesame oil BHT was only found in blendoil at a level of 214 120583g gminus1 TBHQ amount ranged between254 120583g gminus1 in rapeseed oil and 472 120583g gminus1 in corn oil [112]

A number of 19 phenolic compounds were determinedby HPLC during the ripening of cumin seeds The phenoliccompounds were analysed by Reversed-Phase High Perfor-mance Liquid Chromatography with an UV-VIS multiwave-length detectionThe separationwas performed on aHypersilODS C18 column at ambient temperature The mobile phasecomprised acetonitrile and water with 02 H2SO4 The flowrate was established at 05mLmin and gradient elution wasapplied Rosmarinic acid was themain phenolic acid found inthe unripe seedsThen p-coumaric acid was confirmed as theprevalent phenolic in half ripe and full ripe seeds [113] HPLCanalysis of Artemisia capillaris extracts proved that the maincompounds imparting antioxidant capacity were chlorogenicacid 35-dicaffeoylquinic acid and 34-dicaffeoylquinic acid[114]

The HPLC profile of methanolic extracts of Spathodeacampanulata revealed antioxidant potential of this tradition-ally used plant against malaria and inflammation due tothe presence of bioactive compounds such as verminoside(1033) and 1-O-(E)-caffeoyl-beta-gentiobiose (658) [115]Glucosinolates from broccoli were analysed by HPLCafter enzymatic desulfation The HPLC system includeda Spherisorb ODS-2 column and the wateracetonitrilemixture was used for gradient elution of samples Gluco-raphanin precursor of the most active antioxidant glucosi-nolate found in broccoli was assessed as the prevalent com-pound 1406 to 2417 120583molg [116] HPLC chromatographicassay of the methanolic extract of Bambusa textilis McClureindicated active antiradical fractions as presented in Figure 1[87]

42 Spectrometric Techniques421 Studies Based on Nonenzyme Assays The antioxidantactivity of Acacia confusa bark extracts was determined byfree radical scavenging against DPPH The total pheno-lic content was assessed according to the Folin-Ciocalteumethod using gallic acid as a standard The scavengingactivity exhibited against the DPPH free radical diminishedin the following order 345-trihydroxybenzoic acid = 34-dihydroxybenzoic acid = 34-dihydroxybenzoic acid ethyl

Oxidative Medicine and Cellular Longevity 17(A

U)

(min)

016

012

008

004

000

5 10 15 20 25 30

F1 and F2

F9

F11

Figure 1 HPLC chromatogram (at 330 nm) of the methanolicextract of Bambusa with illustration of the antioxidant fractions F1F2 F9 and F11 [87]

ester gt 4-hydroxy-3-methoxybenzoic acid gt 3-hydroxy-4-methoxybenzoic acid gt 4-hydroxybenzoic acid = benzoicacid It has been stipulated that this trend is due to thepresence of catechol moieties in 345-trihydroxybenzoicacid 34-dihydroxybenzoic acid and 34-dihydroxybenzoicacid ethyl ester which impart antioxidant activity [207]

Fruits of Lycium species were subject to sequentialextraction with petroleum ether ethyl acetate methanol n-butanol and water in a Soxhlet extractor All the extractswere analysed for their scavenging potential towards thefree DPPH∙ radical by in vitro method The compositionof each extract was also studied for the Folin-Ciocalteureactive species It was stressed out that the butanol extractsof both species (Lycium barbarum and Lycium ruthenicum)were endowedwith the highest scavenging potential (smallestIC50) A linear relationship (correlation) was establishedbetween the total phenol content (Folin-Ciocalteu assay) andthe radical scavenging potential [107]

A research dedicated to the antioxidant compositioninvestigation and antioxidant capacity determination in Oci-mum basilicum showed that the scavenging effect against theDPPH radical was proportional to the phenolic content towhich flavonoids and caffeic acid derivatives contribute TheDPPH scavenging activity proper to harvested samples (2655and 2243 resp) was greater than the one obtained forcommercial ones (1205 and 1124) considering the one ofBHT as 9477 [109]

Six spice plant samples namely onion (Allium cepa)parsley (Petroselinum crispum) roots and leaves celery(Apium graveolens) roots and leaves and leaves of dill (An-ethum graveolens) were subject to analysis for the total phe-nolic amount and the antioxidant activity assessed by DPPHscavenging The celery leaves exhibited the highest total phe-nolic content namely 16371mg gallic acid equivalents100 gand the highest radical scavenging activity against DPPH[101]

The antioxidant properties of methanol extracts of 15broccoli samples were estimated by DPPH∙ and OH∙ radicalinhibition These activities ranged from 149 120583mol TroloxgDW to 334 120583mol TroloxgDW The sample endowed with

the highest DPPH∙ radical scavenging activity also possessedthe highest phenolic and glucosinolate contents includingglucoraphanin [116]

In another study the antioxidant activity of Clusia flumi-nensis extracts was assessed exploiting the scavenging of thestable free radical DPPH The flavones and flavonols contentwas also determined in order to test the potential correlationwith the antioxidant capacity No significant differences wererevealed between the total flavonoid contents of Clusia flu-minensis in acetone and methanol extracts respectively Theacetone extract was endowed with the highest antioxidantactivity (with almost 2 times smaller EC50 value than theone proper to methanol extract) and highest flavonoid levelHence it has been asserted that acetone is an efficient solventfor antioxidant extraction It has been also suggested that thesubstances with best antioxidant activity in Clusiaceae fruitspossess intermediate polarity [176]

The antioxidant activity of 52 wine samples was assessedspectrophotometrically and expressed as the amount of wineable to engender 50 decolorization of the DPPH radicalsolution per reference to the control (EC50) The obtainedaverage values of EC50 were 201120583L for red and 984 120583L forwhite dry wines The highest EC50 of red dry wines 269 120583L(illustrating the lowest antioxidant capacity) was inferiorto the one proper to white wines with the most reducedantioxidant capacity 564 120583L It was inferred that regardingDPPH radical scavenging red wines are around 5 timesstronger than white wines despite the absence of statisticallysignificant differences between the grape varieties studied aswell as among different wine regions [210]

The total phenolic amount and antioxidant potentialexpressed by the IC50 values (concentration causing a 50DPPH inhibition) were assessed in the seeds of cuminat different ripening stages At full ripening stage forwhich the highest level of total phenolics was determined(1774 and 2515mgGAEgDW) the antioxidant capacity alsoattained its peak with the smallest values of IC50 624and 4216 120583gmL respectively for maceration and Soxhletmethods applied for extraction [113]

Another study was performed to assess the antioxidantand antimicrobial potential of methanol (100 and 80)aqueous extracts of pumelo fruits albedo (Citrus grandisOsbeck) The antioxidant and antibacterial activity of bothcrude extracts and isolated compounds were determinedusing DPPH scavenging and paper disc diffusion methodThe 100 methanol extract was steeped in water at differentpH values and subject to partitioning with ethyl acetateyielding basic acidic neutral and phenolic fractions Theneutral fraction revealed the highest antioxidant potentialand antibacterial efficacy [191]

The antioxidant activities of Artemisia capillaris extractsin different organic solvents (n-hexane ethyl acetate acetoneand methanol) were tested Methanol extracts of Artemisiacapillaris herba possessed the highest phenolic content andwere endowed with the strongest antioxidant power whencompared to the other solvent extracts namely the scaveng-ing potential of three extracts exhibited against the DPPHradical varied as follows ethyl acetate extracts lt acetoneextracts ltmethanol extracts corresponding to the inhibition

18 Oxidative Medicine and Cellular LongevityD

PPH

sc

aven

ging

Concentration (120583gmL)

100

80

60

40

20

0

1 5 10 25 50 100

Figure 2 DPPH radical scavenging activity of Sonchus asperextracts in different solvents at various concentrations Each valuestands for the mean plusmn SD (119899 = 3) of hexan ethyl acetate chloroformand methanol crude extracts of the whole plant and ascorbic acid[88]

percentages of 352 571 and 911 at a dose of 200 ppmrespectively The scavenging potential of 100 ppm methanolextract (908) equaled the one proper to 100 ppm BHT(905) and was very close to the one of 120572-tocopherol(923) The methanolic extract also exhibited the strongestantioxidant activity in the 120573-carotene bleaching system[114]

The antioxidant potential of nonpolar (hexane ethylacetate and chloroform) and polar (methanol) Sonchus aspercrude extracts was assessed by DPPH radical scavengingMethanol extract showed the highest scavenging potential(smallest IC50) followed by chloroform ethyl acetate andhexane extracts as revealed in Figure 2 [88]

The antiradicalic activity against DPPH and the super-oxide anion scavenging activity (in a riboflavin-light-nitroblue tetrazolium chloride system) were determined in thecase of methanolic extracts of Bergia suffruticosa bone andsore healer The whole plant extracts proved dose-increasingscavenging activities versus DPPH∙ and superoxide withEC50 values of 131 120583g and 1394 120583g respectively The Fe3+ toFe2+ reducing ability was also proven to be dose-dependentreaching a maximum for 300120583g extract [90]

In another paper the antioxidant profiling and antiox-idant activities of dried fruits have been assessed namelyprunes apricots raisins and figs [183] The highest concen-tration of carotenoids was present in apricots and figs (107and 108mg 120573 carotene equivalents100 g) Raisins possessedthe highest total phenolic concentration (118 g gallic acidequivalents100 g) and proanthocyanidins (1753mg cyani-din equivalents100 g) Figs presented the highest flavonoid(1056mg quercetin equivalents100 g) and anthocyanin(59mg100 g) amount The antioxidant activities were alsoassessed The apricot aqueous extract had the best reducingpower Agen prune presented the highest antioxidant activityfurnished by the phosphomolybdenum method and theraisin extract in ethanol showed the best DPPH∙ quenchingcapacity [183]

A study based on ABTS scavenging ability proves thatrosemary extract exhibits an antioxidant capacity equivalentto the one of BHA and superior to the one proven byBHT The chile ancho extract exhibits a lower antioxidantcapacity when compared to rosemary and both BHT andBHA In the case of rosemary due to the preponderance ofethanol in the extraction mixture the polyphenol amountincreases being the most elevated for an ethanol water ratioof 75 25 The rosemary extract is rich in rosmarinic acidcarnosic acid and carnosol In the case of chile ancho themaximum extracted polyphenol amount is obtained for anethanol water ratio of 50 50The chile ancho extract containsflavonoids (luteolin quercetin) carotenoids ascorbic acidand capsaicinoids [178]

The phenolic content and antioxidant activity of Vitisvinifera extracts were followed under different storage con-ditions The total phenolic content was determined by Folin-Ciocalteu method and the antioxidant capacity by the scav-enging ability versus the ABTS cation radical The extractproved stable for up to one year at storage in darkness as ahydroalcoholic solution at 4∘C or as a freeze-dried powderat 25∘C The total phenolic content was found constantat different pH values (30 50 70 and 90) for up to400 days while the antioxidant capacity diminished at pHvalues greater than 50 The thermal treatment (at 121∘Cfor 15 minutes at different pH values) neither decreasednor increased the ABTS radical cation-scavenging activityNevertheless it was found that the total phenolic contentincreased after heating at all pH values tested [181]

Another study was dedicated to the assessment of theantioxidant potency of phenolic substances from wild Alge-rian medicinal plants by chemical and biological methodsAnthemis arvensis and Artemisia campestris had the highestphenolics amounts (1152 and 1034mggDW resp) andthe most enhanced antioxidant power assessed by ABTS∙+decolorization (0726 and 0573mmol TEACg DW resp)They also promoted an enhanced delay of free radical-induced red blood cells hemolysis even when compared tocaffeic acid the reference antioxidant endowed with the mosteffective inhibition capacity [103]

Both lipophilic and hydrophilic components of 24 cerealgrains fromChina were spectrophotometrically assessed Forwater-soluble fractions of the analysed grains the FRAPvalues varied from 087 plusmn 008 to 11469 plusmn 215 120583mol Fe(II)gDW Black rice exhibited the highest FRAP value followed byorganic black rice purple rice and organic black millet Withrespect to the fat-soluble fractions the FRAP values rangedbetween 427 plusmn 019 and 2191 plusmn 127120583mol Fe(II)g with redrice buckwheat organic black rice and brown rice exhibitingthe most elevated FRAP values The TEAC values (relyingon the ability of antioxidants to scavenge ABTS∙+) rangedbetween 018 plusmn 001 and 2528 plusmn 107 120583mol TroloxgDW forthe water-soluble fractions with black rice organic blackrice buckwheat and red glutinous rice exhibiting the highestvalues For fat-soluble fractions the TEAC values varied from006 plusmn 004 to 522 plusmn 029 120583mol Troloxg The antioxidantcapacities of cereals showed a significant correlation betweenthe FRAP value and the TEAC values A strong correlationbetween antioxidant capacity and total phenolic content


(Folin-Ciocalteu) was also obtained indicating that phenoliccompoundsmainly contribute to the antioxidant capacities ofthese cereals [105]

The total antioxidant capacity and phenolic content wereassessed for 70 medicinal plant infusions Melissae foliuminfusions exhibited a ferric reducing antioxidant powergreater than 20mmole Fe(II)L and a phenol antioxidantcoefficient greater than 3The DPPH radical scavenging abil-ity ofMelissae folium phenolics was close to that of catechinWith respect to ABTS radical cation scavenging Melissaefolium phenolics exhibited superior efficacy in comparison toTrolox and vitamin C [212]

Species belonging to Malvaceae family (Sidastrum mi-cranthum (A St-Hil) FryxellWissadula periplocifolia (L) CPresl Sida rhombifolia (L) E H L and Herissantia crispa L(Brizicky)) were investigated for the total phenolic contentDPPH radical scavenging activity and Trolox equivalentantioxidant capacity The antioxidant activity of the crudeextract aqueous and organic phases and isolated flavonoidskaempferol 37-di-O-120572-L-rhamnopyranoside (lespedin) andkaempferol 3-O-120573-D-(610158401015840-E-p-coumaroyl) glucopyranoside(tiliroside) was assessed A firm correlation was noticedbetween total polyphenol content and antioxidant activity ofthe crude extract of Sidastrum micranthum and Wissadulaperiplocifolia this was not the case for Sida rhombifolia andHerissantia crispa The ethyl acetate phase exhibited thebest total phenolics content as well as antioxidant capacityin DPPH and TEAC assays followed by the chloroformphase To lespedin present in the ethyl acetate phase of Wperiplocifolia andH crispa no significant antioxidant activityhas been ascribed (IC50 DPPH 101992 plusmn 6899mgmLTEAC 5270 plusmn 047mgmL) tiliroside isolated from Wperiplocifolia H crispa and S micranthum had small IC50(163 plusmn 086mgmL) proving better antioxidant capacity asprovided by TEAC method [213]

The antioxidant properties of Diospyros bipindensis(Gurke used in Baka traditionalmedicine against respiratorydiseases) stembark were assessed by ABTS DPPH andORAC assays The antioxidant properties that contribute tothe bioactivity of the plant extract were mainly imparted byismailin [179]

During the investigation of the antioxidant poten-tials of some cereals and pseudocereals polyphenol drymatter extracts from seeds of buckwheat rice soybeanamaranth and quinoa (obtained with 12M HCl in 50methanolwater) showed better inhibition of lipid peroxi-dation than the ones extracted with 50 methanolwaterand were close to the antioxidant activity of BHT at con-centration of 02mgmL The antioxidant activities of seedextracts determined by DPPH∙ ABTS∙+ scavenging and 120573-carotene bleaching proved strong correlation with the totalpolyphenols assessed by Folin-Ciocalteu assay It has beenconcluded that proteins do not significantly contribute to thesamplesrsquo antioxidant activity and that buckwheat followed byquinoa and amaranth are themost proper as cereal substitutes[214]

A series of foods usually consumed in Italy were analysedfor their antioxidant capacity by TEAC TRAP (relying onthe protective action of antioxidants over the fluorescence

diminution of R-phycoerythrin in a monitored peroxida-tion reaction) and FRAP Among vegetables spinach hadthe highest antioxidant capacity in the TEAC and FRAPassays followed by peppers while asparagus had the greatestantioxidant capacity in the TRAP assay Among fruits berries(blackberry redcurrant and raspberry) possessed the highestantioxidant capacity in all assays With respect to beveragescoffee had the greatest total antioxidant activity regardless ofthe technique followed by citrus juices As for oils soybeanoil had the highest antioxidant capacity followed by extravirgin olive oil whereas peanut oil proved less effective [215]

The in vitro antioxidant activity of wines has beeninvestigated by a series of determinations such as ORACABTSDPPH andDMPDquenchingAlso the total phenolicindex was assessed for the 41 samples subject to analysisRed wines necessitated solid phase extraction to discriminatethree main fractions ABTS DPPH and ORAC provided thesame reactivity ranking of the analysed fractions fraction2 (flavan-3-ol and anthocyanins) showed the best activityfollowed by fractions 1 (phenolic acids) and 3 (flavonols)Nevertheless a much reduced reactivity of fraction 2 com-ponents (anthocyanins and flavanols) towards DMPD∙+ wasnoticed which is consistent with the lower correlation withthe total phenolic index and the smaller difference (red versuswhite wines) in comparison to the other methodsrsquo results[216]

422 Studies Relying on Both Enzyme-Based and NonenzymeAssays The antioxidant activity of the ethyl acetate and n-butanol extracts along with that of seven flavonol glyco-sides isolated from Dorycnium hirsutum aerial parts wasassessed using the DPPHmethod and the lipoxygenase assayWith respect to the inhibition activity towards the DPPHradical kaempferol 3-O-120572-L-rhamnopyranoside possessedthe highest antioxidant activity (1226 Trolox equivalents)The lipoxygenase assay has been also performed in thepresence of linoleic acid and commercial lipoxygenase at pH= 680 and the hydroperoxide generation was monitored at235 nm It was proven that kaempferol 3-(410158401015840-O-acetyl)-O-120572-L-rhamnopyranoside-7-O-120572-L-rhamnopyranoside exhibitedthe best antioxidant protection activity in the lipid peroxida-tion systemThe butanolic extract proved less active than theethyl acetate residue which confirmed the higher flavonoidlevel assessed in the latter [217]

The scavenging properties of the DPPH radical and thexanthine oxidase inhibition activity were determined formethanol extracts of Lantana camara obtained from differentplant partsThe absorbance diminution of theDPPH solutionwas measured at 517 nm and the XO inhibition assay wasbased on uric acid production estimated according to theabsorbance increase at 290 nm Allopurinol (XO inhibitor)was used as positive control The DPPH assay showed thatthe leaf extract had the best antioxidant activity and thehighest phenolic content was also found in the leaves 24550plusmn 354mg gallic acidg [180]

The in vitro antioxidant capacities of methanolic extracts(80) prepared from Cornus mas L Diospyros kaki L andLaurocerasus officinalisRoemwere tested by a series of recog-nizedmethods DPPH superoxide radical scavenging FRAP


CUPRAC metal-chelating capacity 120573-carotene bleachingtest in a linoleic acid emulsion system and TEAC [186]For the superoxide radical scavenging the extract wassubject to reaction with a substrate solution containingsodium xanthine and 2-(4-iodophenyl)-3-(4-nitrophenol)-5-phenyltetrazolium chloride Xanthine oxidase was used asbiocatalyst and the absorbance increase was monitored at505 nm Gallic acid was used as reference phenolic [143 186]The Folin-Ciocalteu assay of total phenolic content involvessample reaction with a mixture of phosphomolybdate andphosphotungstate in the presence of sodium carbonate 20Absorbance readings of the blue molybdenum-tungstencomplex formed in the presence of reducing phenolics aretaken at 765 nm after incubation with gallic acid as [218]Diospyros kaki yielded the best results except for the 120573-carotene bleaching assay Also good correlationwas obtainedbetween the phenolic profile and antioxidant activity Nometal-chelating activity was shown [186]

The isolation and characterization of bioactive poly-phenolic compounds from bitter cumin (condiment andalso stimulant carminative and astringent in traditionalAyurvedic medicine) were performed by various spec-trophotometric determinations to assess their scavengingactivities The bitter cumin seed extract showed enhancedantioxidant activity at 120583g amounts trapping effectivelyDPPH∙ lipid peroxyl hydroxyl and superoxide anionradicals Superoxide anions were generated in the sam-ples containing nitroblue tetrazolium nicotinamide adeninedinucleotide-reduced and phenazine methosulphate Theabsorbance taken at 560 nm decreased in the presence ofcumin extracts pointing towards superoxide anion scaveng-ing activityThemeasurement of lipid peroxidation activity inrat liver microsomes was performed incubating microsomalprotein with ferrous sulphate and ascorbic acid yieldingmalonyl dialdehyde which led to the assessment of TBARSin the presence of thiobarbituric acid with readings takenat 535 nm The presence of cumin antioxidants led to thedecrease of microsomal lipid peroxidation assessed in thepresence of soybean lipoxygenase and linoleic acid Theabsorbance due to lipid hydroperoxides was measured at234 nm Cumin phenolics decreased lipid peroxidation andproved radical scavenging ability in Fenton OH-initiatedDNA damage [106]

Twelve methanolic extracts from rosemary leaves har-vested from different locations of Turkey at four differenttimes of the year were analysed for their radical scavengingcapacities and antioxidant activities by applying differenttechniques DPPH radical scavenging activity Trolox equiv-alent antioxidant capacity and reversing H2O2-induced ery-throcyte membrane lipid peroxidation Human erythrocytesuperoxide dismutase and catalase activities after in vitroincubation with the extracts were also tested in order tocheck altered enzymatic efficiency Rosmarinus officinalissamples were collected from three different locations namelyCanakkale (southern Marmara region the coolest climate)Izmir (Aegean region moderately hot) and Mersin (EasternMediterranean region the hottest) on four different intervalsas follows December 2003 (denoted as C-S1 I-S1 and M-S1resp) March (C-S2 I-S2 and M-S2) June (C-S3 I-S3 and

M-S3) and September 2004 (C-S4 I-S4 and M-S4) TEACvalues ranged between 117 and 53mmol Troloxkg FWwith CanakkalendashMarch samples having the highest value(117mmolkg) With respect to the H2O2-forced human ery-throcyte membrane lipid peroxidation test most of rosemaryextracts acted efficiently except for C-S2 I-S1 IS2 I-S3 andI-S4 I-S2 and I-S3 even exhibited prooxidant activity andcaused an increase of MDA The M series together with C-S4 have been proven to be the most active antioxidants in thein vitro test M-S4 extract showed closest effect to the threereference antioxidants BHT vitamin Cvitamin E mixtureand quercetin All extracts caused significant increases inSOD activity except C-S1 I-S1 I-S4 and M-S4 M seriesextracts did not affect CAT activity while C and I seriessignificantly decreased CAT activity

All extracts proved high ability to quench the free rad-icals (DPPH and ABTS) and to inhibit malonyl dialdehydeformation On the whole the obtained results revealed thatthe plants harvested in September possess higher levels ofactive constituents and superior antioxidant activities incomparison to those harvested in other year seasons Plantsharvested from the Izmir region had lower total phenoland active constituent levels and hence smaller antioxidantactivity These differences were assigned to the variouscompositions in bioactive compounds characterizing theplants harvested from different locations and in variousyear seasons the rosmarinic acid contents in the Izmir andMersin samples increased in summer with a maximumin September (304mg gminus1) and decreased in Decemberattaining aminimum inMarch (04mg gminus1) In theCanakkalesamples the rosmarinic acid level raised progressively fromDecember to September As in the case of rosmarinic acid thelevels of carnosol peaked in September and then diminishedstepwise attaining a minimum in March For carnosic acidseasonal differences were not as significant as for rosmarinicacid and carnosol all September samples possessed higherlevels of carnosic acid Mersin samples exhibited the highestand lowest carnosic acid levels in September and Marchrespectively [104]

111 samples of yerba mate from three (Southeast SouthCentral and Metropolitan Area of Curitiba) regions of theBrazilian state of Parana were subject to analysis of the totalphenolic content (TPC) by near infrared spectroscopyMulti-variate calibration models were developed to assess the TPCfrom the NIR spectra using partial least squares regressionNamely the characteristic spectral signal of phenolic groups(4670 cmminus1) led to the development of multivariate modelsfor quantifying total phenolics The reference experimentalresults and those predicted by the partial least squaresregressionmodel obtained for the 26 samples ranged between2728 and 4455mg gminus1 [219]

In another study the antioxidant action of different fla-vonoids (quercetin glabridin red clover extract and theisoflavones mixture Isoflavin Beta) was investigated to assessthe appropriateness as topical formulation against free radi-cals-induced damageHorseradish peroxidase catalyses lumi-nol oxidation to 3-aminophthalate byH2O2 followed by lightemission at 428 nm at pH 740 in 01M phosphate buffer


The reduction of chemiluminescent signal in the presence ofantioxidants takes account on their antioxidant potential Allsamples proved their capacity to inhibit oxidative damage asdepending on quercetin and beta isoflavin level The highestchemiluminescence inhibition was noticed for glabridin anddry red clover extract [220]

43 Electrochemical Techniques431 Linear Sweep Techniques Cyclic Voltammetry The anti-oxidant capacity of dry extracts of green tea black tea rose-mary and coffee acerola and acaı was assessed voltammet-rically at a glassy carbon electrode Methanol proved betterefficacy in extracting antioxidant principles The antioxidantcapacities given by anodic area on the voltammogram andexpressed as mg ascorbic acid equivalents ranked as followsgreen tea gt black tea gt rosemary gt arabica coffee gt herb teagt acerola gt quality tea gt acaı [221]

A cyclic voltammetric study of the electrooxidation ofphenolic compounds present in wine revealed a pivotalinfluence of the structure on the propensity to undergo oxi-dation Compounds with an orthodiphenol group (catechinepicatechin quercetin and gallic caffeic and tannic acids)and morin possess the greatest antioxidant potential and areoxidized at lowpotentials at about 400mV Ferulic acid trans-resveratrol and malvin as well as vanillic and p-coumaricacids that have a solitary phenolmoiety inmany cases close toa methoxy function are less electrooxidizable Anthocyaninsdetermine the existence of a peak at 650mV It was alsoassessed that phenolics that imparted a first peak in the370ndash470mV range on the voltammogram can be secondlyoxidized at around 800mV catechin and epicatechin byreason of the meta-diphenol groups on the A-ring quercetinowing to the -OH group on the C-ring and gallic acid due tothe third -OH group placed next to the orthodiphenolmoietyoxidized during the first wave [222]

A voltammetric electronic tongue system composed ofan array of modified graphite-epoxy composites and a goldmicroelectrodewas applied in the qualitative and quantitativeanalysis of polyphenols in wine Samples were analysed bycyclic voltammetry and did not necessitate sample pretreat-ment The analytical responses were processed by discretewavelet transform in order to compress and extract theessential features of the voltammetric analytical responsesExternal test subset samples results correlated well withthe ones furnished by the Folin-Ciocalteu assay and UVabsorbance polyphenol index (I280) for amounts from 50 to2400mg Lminus1 gallic acid equivalents [223]

BHA BHT andTBHQ in edible oil samples were assessedby first derivative voltammetry at glassy carbon electrodemodified with gold nanoparticles First derivative pretreat-ment was applied to the linear sweep voltammetric signalsaiming at minimizing noise influence The values of the peakpotentials of 0273 0502 and 0622V allowed discriminationbetween TBHQ BHA and BHT with detection limits as lowas 0039 0080 and 0079 120583gmLminus1 for the three aforemen-tioned analytes BHA content ranged between 193 120583g gminus1 inrapeseed oil and 566 120583g gminus1 in sesame oil BHT was onlyfound in blend oil at a level of 207 120583g gminus1 TBHQ level

ranged between 268 120583g gminus1 in rapeseed oil and 484 120583g gminus1 incorn oil Interference studies indicated that the determinationof all three compounds in commercial edible oil sampleswas not significantly affected by the common interferents2-fold ascorbic acid and 10-fold vitamin E phthalate andcitric acid concentrations exerted no significant influence onthe peak currents of the three synthetic food antioxidantsascorbic acid peak appeared at 0437V and did not hinderthe analytical signals of the three analytes Vitamin E andphthalate and citric acid did not show peaks in the potentialrange of 010ndash080V Metal ions (K+ Na+ Ca2+ Fe2+ Mg2+and Zn2+) and some of the most significant anions (Clminus IminusSO32minus SO4

2minus NO3minus CO3

2minus PO43minus and CH3COOminus) did not

interfere also up to a 100-fold increase in their concentrations[112]

432 Differential Pulse Voltammetry Sesamol and lignanscontents in sesame tahina and halva were assessed bypolarography and stripping voltammetry Differential pulsepolarography used a capillary hanging mercury drop elec-trode In cathodic stripping sesamol reacts forming areduced derivative which is oxidized yielding a cyclicvoltammetric peak The cathodic stripping voltammetricassessment involved preconcentration (when sesamol accu-mulates to the electrode-surface at minus1650mV) and scanning(when analyte stripping takes place in the potential rangeof minus1650mV to minus2250mV) Using these electrochemicalmethods sesamol was assessed at levels of 026ndash032mg100 goil in three varieties of sesame 1098ndash1233mg100 g oil intahina and 497ndash912mg100 g oil in halva [224]

The antioxidant activity of flavonoids (catechin querce-tin dihydroquercetin and rutin) was voltammetricallyassessed at a glassy carbon working electrode and the meas-ured redox potentials were correlated to the antioxidantactivity results Differential pulse measurements relied onmolecular oxygen cathodic reduction at 50mV sminus1 in the 0ndash800mV potential range and for an optimal pulse amplitudeof 10mV The antioxidant activity coefficient was assessedconsidering O2 reduction current in the presence of addedantioxidants and the limiting O2 current in the absence ofantioxidants To check reversibility and electrooxidationmechanism cyclic voltammetric assay was performed forthe tested flavonoids (1ndash10 120583mol Lminus1 in phosphate buffer0025M pH = 686) in the potential range of 0ndash1000mV at50mV sminus1 All flavonoids presented reversible peaks in therange of 300mVndash400mV The intensity of the CV oxidationpeak (assigned to the deprotonation of the catechol moietynamely of the 31015840-OH electron-donating group) increaseswith the dihydroquercetin concentration The peak intensityalso depended linearly on the square root of the scan rateso it was concluded that the oxidation of this flavonoid waslimited bymass transfer Both the easiness of electron transferreflected by the redox potentials (in CV) and the antioxidantactivity (assessed byDPV) correlatedwith the following trendof increase rutinndashdihydroquercetinndashcatechinndashquercetin[225]

A DNA-modified carbon paste voltammetric biosensorfunctioned on the basis of DNA layer oxidative insults


I(120583

A)

E (mV)minus1000 200 400 600 800 1000

560

520

480

440

400

360

320

280

240

200

160

120

80

40

0

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

Figure 3 Differential pulse voltammograms at a Pt workingelectrode for different ascorbic acid concentrations (mM) 20 (1)15 (2) 10 (3) 5 (4) 25 (5) 125 (6) 0625 (7) and 031 (8) pulseamplitude 75mV pulse period 125ms and potential scan rate50mVs [89]

induced by Fenton OH∙ radicals The electrooxidation of theleft unimpaired adenine bases can give an oxidation productable to catalyse NADH oxidation [226 227] Antioxidantsscavenged hydroxyl radicals and the current which emergedfrom NADH oxidation increased as a result of a largernumber of unoxidized adenine molecules [226] Ascorbicacid has been proven to be the most effective antioxidantas it determined the most significant electrocatalytic currentincrease Among the analysed beverages the greatest antiox-idant capacity value was exhibited by lemon flavour namely480 plusmn 20120583M calculated as per reference to ascorbic acidstandard [226]

Differential pulse voltammetry a Pt working electrodeallowed for ascorbic acid quantitation in fruit juices basedon its electrooxidation as presented in Figure 3 [89]

433 Square Wave Voltammetry Square wave voltammetryat disposable screen-printed carbon electrodeswas developedfor the polyphenol antioxidant screening in freshly squeezedblackcurrant and strawberry juices from various cultivarsand at different maturity stages Prior to the electrochemicalassessment the anthocyanins and nonanthocyanins wereseparated by solid phase extraction It was proven that thecharges passing to 500 and 1000mV correlated well withthe antioxidant activity as well as with anthocyanin andascorbate levelsThe use of disposable screen-printed sensorswas able to surpass the shortcoming of electrode deactivationdue to fouling by the polymeric film formed through couplingof phenoxyl radicals during electrooxidation Neverthelessit was asserted that phenolics other than anthocyanins withlow formal oxidation potentials should be quantified on the

basis of sensor cumulative responses at 300mV Blackcurrantjuices possessed high oxidation peaks at low potentials(lt400mV) and so enhanced antioxidant capacities [228]

The phenolic content of extra virgin olive oils wasassessed by an array of 12 voltammetric electrodes five lan-thanide bis-phthalocyanines-based sensors six polypyrrole-based sensors and one unmodified carbon paste electrodeApart from the peaks related to phthalocyanine a peakdue to the redox process associated with the polyphenolicfraction was also present as a shoulder in the domainof 300ndash500mV (assigned as first peak) The oxidation oflanthanide bis-phthalocyanines complexes occurs at 055Vin KCl electrolyte and at 066V in the oil extract so theantioxidant features of polyphenols render the oxidation ofphthalocyanine more difficultThe electrocatalytic efficacy ofphthalocyanines enables a more facile oxidation of phenolsfor the extract with the highest polyphenol content whenusing a bare carbon paste electrode the peak assigned topolyphenols appeared at 068V and at 05 V when using apraseodymium bis-phthalocyanine electrode The polyphe-nol content of the extracts ranged between 40306mg kgminus1and 99025mg kgminus1 [209]

Square wave voltammetry and cyclic voltammetry at dif-ferent pH values was performed to investigate the antioxidantcapacity of cashew nut shell liquid components such ascardol cardanol and tert-butylcardanol which were char-acterized by lower oxidation potentials in comparison toBHT (Epa = 0989V) Cardol possessed the smallest Epa(0665V) and hence best antioxidant potential among thetested compounds followed by tert-butylcardanol (Epa =0682V) and cardanol (Epa = 0989V) A linear shift of thepeak potential to more negative values with the pH increasewas noted for all antioxidant compounds Increasing the pHof the electrolyte resulted in a nonlinear decrease of the peakcurrents so the highest values were obtained at pH = 20[229]

434 Stripping Voltammetry Adsorptive stripping voltam-metry has been applied for the determination of caffeic acidat a Pb film electrode The working electrode was obtainedin situ on a glassy carbon basis The analyte accumulates byadsorption on the lead film electrode and is subsequentlyelectrooxidized during the stripping step The analyticalsignal depended linearly on caffeic acid concentration in therange of 1 times 10minus8 to 5 times10minus7M with a detection limit of 4 times10minus9M in acetate buffer pH = 40 By operating in the squarewave voltammetric mode this technique proved viable inthe determination of caffeic acid in the herbs of PlantagolanceolataThe caffeic acid amount obtained by the developedvoltammetric method was 1074120583gg of dried plant with RSDof 295 [93]

435 Hydrodynamic Techniques Amperometry The deter-mination of flavonoids and ascorbic acid in grapefruit (Citrusparadisi antioxidant antiallergic and anticarcinogenic) peeland juice has been performed by capillary electrophoresiswith electrochemical detectionHydrodynamic voltammetricmeasurements aimed at optimizing operational parametersAn applied potential of +095V (versus SCE) was chosen


for an optimum signal to noise ratio and a pH of therunning buffer of 90 because at this value a rapid andefficient separation was obtained between the five flavonoids60mM was the best buffer concentration with higher val-ues negatively influencing the detection limit Hesperidinnaringin hesperidin naringenin rutin and ascorbic acidwere separated and quantified in grapefruit juice by capillaryelectrophoresis with electrochemical detection comparingthe migration times with those of the standards Hesperidinnaringin and ascorbic acid were assessed in grapefruit peelextract with good peak repeatabilities and recoveries [230]

A sequential injection method with amperometric detec-tion was developed for the total antioxidant capacity assess-ment in commercial instant ginger infusion beverages Themethod relied on the decrease of the cathodic current ofABTS∙+ at a glassy carbon electrode in phosphate buffer pH= 70 after reaction with antioxidants in the sampleThe totalantioxidant capacity ranged between 0326 plusmn 0025 and 1201plusmn 0023mg gallic acid equivalentsg sample [231]

A laccase-based amperometric biosensor allowed for theoptimized determination of phenolic content in tea infusionsThe enzyme from Trametes versicolor was immobilized byentrapment within polyvinyl alcohol photopolymer fixedonto disposable graphite screen-printed electrodes An oxi-dation peak was noticed at 270mV only in the presenceof hydroquinone the enzyme substrate The amperometricresponses of the biosensor were registered for three testeddiphenols under the optimal experimental conditions 01Macetate buffer at pH 470 30∘C and minus300mV The highestsensitivity was obtained for catechol 1882 plusmn 076 nA 120583Mminus1whereas the lowest one was obtained for resorcinol 0110plusmn 0002 nA 120583Mminus1 The equivalent phenol content was com-prised between 40 and 1092mg caffeic acid equivalentsLsample for orange leaves and palo azul infusion respectively[232]

A laccase-based biosensor aimed at polyphenols deter-mination from in vitro Salvia cultures The biosensor wasdeveloped by drop casting 3mL of laccase solution andstabilization with 01 Nafion solution on a screen-printedcarbon electrode Chronoamperometric measurements wereperformed in 01M phosphate buffer pH 450 at minus30mVversus an AgAgCl reference The results as rosmarinicacid equivalent content (chosen as standard as it has beenidentified as the major phenolic in the samples analysedby chromatography and MS screening) ranged from 978 plusmn82 120583gg fresh material for Salvia maxima to 1622 plusmn 113 120583ggfresh material for Salvia verde with a limit of detection of 42times 10minus7M The biosensor retains more than 85 of its initialanalytical response up to 90 days The Michaelis-Mentenkinetic apparent constant of 83times 10minus6Mrevealed the enzymeaffinity for the substrate [110]

A tyrosinase-based biosensor was prepared by enzymeimmobilization on single wall carbon nanotubes screen-printed electrodes modified with iron(II) phthalocyanineThe electrochemical behavior of the biosensor was studiedwith optimization of the parameters the cyclic voltammo-grams in catechin solution do not present peaks relatedto phthalocyanine but exhibit only the peak related to the

reduction of the o-quinone that resulted from tyrosinase-catalysed catechin oxidationThis peak points to the retainingof the catalytic activity of tyrosinase after immobilizationThemaximum analytical response was obtained at 015 V pH =70 in phosphate buffer solution The amperometric signalat increasing catechin concentrations was registered with asensitivity of 0937 120583A 120583Mminus1 and a 089 120583M detection limitThe polyphenol content of green tea samples as mg catechinranged from 19 plusmn 145 to 98 plusmn 386 [233]

A superoxide dismutase-based biosensor allowed for theamperometric antioxidant activity determination in aromaticherbs olives and fruits Superoxide dismutase was immo-bilized between a cellulose acetate membrane and a dialysismembrane Enzymic xanthine oxidation yields superoxideradical anion and the disproportionation of the latter bysuperoxide dismutase results inmolecular oxygen and hydro-gen peroxide occurrence [234]

xanthine +H2O +O2 997888rarr uric acid + 2H+ +O2∙minus

2O2∙minus + 2H+ 997888rarr H2O2 +O2

(6)

Finally the electrochemical response correlatable to thesuperoxide radical concentration is imparted by H2O2 oxi-dation at the Pt anode and 650mV As the electroactivesuperoxide anion radicals are trapped by antioxidants in thesample the amperometric signal diminishes The highestantioxidant capacity was exhibited by sage as herb and bymedlar among analysed fruits [234]

436 Biamperometry This method relies on recording ata small potential difference the current intensity betweentwo identical working electrodes found in a solution wherea reversible redox couple (Fe3+Fe2+ I2I

minus Fe(CN)63minus

Fe(CN)64minus) is present The analyte reacts with the indicating

redox couple the selectivity of the technique depending onthe specificity of the reaction involving the oxidized form ofthe redox pair and the antioxidant [158]

Particularly in DPPH∙DPPH biamperometry antioxi-dants react with DPPH∙ (radical form) decreasing its concen-tration and generating DPPH (reduced form) The DPPH∙reduction at one electrode gives rise to a cathodic currentproportional with the concentration of the radical formwhereas the oxidation of DPPH at the other electrode yieldsan anodic current proportional with the molecular formconcentration When employed working conditions are assuch for the radical form concentration to be smaller than theone proper to the molecular form cathodic current is limitedby the lower concentration of DPPH∙ radical in the indicatingmixture DPPH∙DPPH biamperometry was employed in theanalysis of tea wine and coffee using glassy carbon elec-trodes [158] ABTS∙+ABTS biamperometry enables analysisof juices tea and wine [159] as well as wines and spirits withexcellent sensitivity 0165 nA120583M Trolox [160]

Samples of Brazilian woods and oak (Quercus sp)extracts were subject to ceric reducing antioxidant capacity(CRAC) analysis at a boron-doped diamond film electroderelying on Ce4+Ce3+ redox couple Chronoamperometricdeterminations enabled quantification of the decrease of


Ce4+ concentration which was caused by its reduction byantioxidants present in the sample The following variationof the antioxidant activity of analysed extracts was observedoak (Quercus sp) (173) gt cabreuva-vermelha (Myroxylonbalsamum) (105) gt cabreuva (Myrocarpus frondosus) (090)gt imbuia (Octea porosa) (071) gt pequi (Caryocar brasiliense)(031) [235]

The ceric reducing antioxidant capacity assay was alsoexploited given its direct electron transfer facility for deter-mining the antioxidant capacity of eight antioxidant com-pounds The developed technique was based on observingthe decrease of Ce4+ concentration after its reaction withantioxidants The following trend of variation of antioxi-dant capacities resulted from this comparative investigationwhich relied on chronoamperometric measurements tannicacid gt quercetin gt rutin gt gallic acid asymp catechin gt ascorbicacid gt butylated hydroxyanisole gt Trolox The results wereconsistent with those furnished by the applied conventionalFRAP assay [236]

Vitamin C assessment relied on the oxidation of theanalyte at acidic pH by I2I

minus employed as oxidizing agentThebiamperometric detection of the amount of iodine consumedallowed for the assessment of vitamin C with a linear rangeof analytical response comprised between 5 times 10minus5 and 5 times10minus4M a 108 RSD (119899 = 10 119888 = 25 times 10minus4M) and highthroughput of 60 samples hminus1 [237]

437 Potentiometric Assay The analytical signal representedby the potential change is the result of the variation of anionic species concentration A flow injection potentiometricmethod was developed to rapidly and reproducibly evalu-ate the antioxidative ability characteristic for several aque-ous plant extracts This potentiometric technique relies onrecording the potential shift in the ferricyanideferrocyanidemediator system in the presence of antioxidants which reactwith the oxidized form of the redox pair modifying theconcentration ratio between the oxidized and reduced formsThe developed potentiometric method used as detector aPt electrode transducer based on logarithmic dependencewhich provided the antioxidant activity of several hydrosol-uble antioxidants (ascorbic acid pyrocatechol pyrogallolcaffeic acid chlorogenic acid gallic acid tannic acid uricacid l-cysteine and Trolox) The total antioxidant activity ofaqueous fruit extracts was comprised between 0066 plusmn 0002ascorbic acid equivalents (for lemon) and 0490 plusmn 0001 (fororange) The tea infusionsrsquo values ranged between 360 plusmn 01ascorbic acid equivalents for Dolche vita and 180 plusmn 02 forSweet osman [161]

A linear potentiometric response versus ascorbic acid atan iodine-modified platinumelectrodewas obtained between10 times 10minus5 and 10 times 10minus3M in model solutions The studyalso assessed the contribution of ascorbic acid to the totalantioxidant capacity of aqueous extracts of hips hop conesand lemon juice namely 260 016 and 15 respectively[238]

In Table 3 a synoptic view of relevant examples of totalantioxidant capacity assessment in plants is given

5 Critical Perspective and Conclusive AspectsRegarding Performances of Extraction andDetection Mode

As previously discussed in this review the first step isrepresented by the choice of the adequate extraction methodand solvent and here the nature of the sample and containedactive principles as well as the analytical technology subse-quently applied should be considered Detailed discussionsdevoted to the choice of the proper solvent as well as to theextraction methodology are given in specific cases

Ethanol methanol and water due to their polarityfavor the extraction of polar substances such as phenolicsand flavonoids Owing to its low toxicity and being anorganic solvent ethanol is employed with high frequencyMethanol toxicity hinders somehow its use Nonpolar sol-vents like ether as well as solvents endowed with low polarity(chloroform ester acetone etc) are proper for particularcases and have limited availability [18] Phenolic compoundsfrom M pubescens were extracted by maceration employingcomparatively solvents with various polarities It has beenrevealed that the use of aqueous methanol (50) aqueousethanol (50) and aqueous acetone (50) imparted thehighest antioxidant capacity values The aqueous methanol(50) and the aqueous ethanol (50) extracts possessed thehighest polyphenol content [239] The differences betweentwo techniques applied to phenolic extraction from Ouratealucens and Acomastylis rossii namely conventional sonica-tion (shaker) bath and homogenizer method revealed abetter performance of the latter Sonication efficacy dependson the cell wall disruption during grinding and the betterhomogenizer performances were attributed to efficacious cellwall breakdown [240]

Three genotypes of horseradish roots were subject toextraction employing conventional solvent as well as Soxhletextraction The solvents endowed with the most potentextractive power were ethanol and ethanolwater mixtureThe total phenolic content obtained in Soxhlet extractsproved superior to the one obtained by conventional solventextraction Nevertheless the DPPH∙ scavenging potentialwas not increased So in this case by applying Soxhletextraction compounds other than antioxidants can takepart in the extraction [241] Soxhlet extraction performanceswere compared to those of maceration in the case of cuminseeds and it was concluded that the greatest polyphenolsand flavonoid contents were obtained following Soxhletextraction whereas employing maceration resulted in betterantiradical activity [113]

Vortex extraction led to superior performances whencompared to sonication and shaking for phenolics extractionfrom oregano leaves as proved by the results of total phe-nolic content assay and scavenging activity determination byDPPH∙ Its efficacy has been proven to be solvent dependentwith best performances being obtained with acetone water[242]

The comparative analysis of both conventional and non-conventional extraction techniques applied on the same plantmaterial (Quercus infectoria extract) revealed that the super-critical CO2 extraction resulted in lower extraction yield


in comparison to Soxhlet conventional technique thoughthe antioxidant capacity and selectivity with respect to totalphenolics given by supercritical CO2 extraction has beenproven to be higher than the one imparted by Soxhletextraction [243]

Various extraction methods (refluxing sonication bathultrasonic homogenizer and microwave) were applied tothe aerial roots of Rhaphidophora aurea The ultrasonicand microwave assisted extraction gave maximum efficiencyreduced the costs and the time limited solvent use andresulted in a good yield compared to the other investigatedtechniques It has been concluded from this comparativeinvestigation that the ultrasonic homogenizer extractionmethod can be regarded as standard technique for ethylacetate and ethanol extraction whereas microwave assistedextraction has been proven to be the most appropriate whenwater is used as solvent [244]

Grape resveratrol extraction performances were inves-tigated by liquid-liquid extraction solid-liquid extractionpressurized liquid extraction-solid phase extraction andsupercritical carbon dioxide extraction and in all situationsthe yield can be improved by postharvest ultrasonicationfungal pathogens in vitro AlCl3 treatment and UV-C radi-ation [245]

The health benefits of plant-derived products have beenalready stated the lipid oxidation delaying ability led to pre-venting the occurrence of mutagenic and carcinogenic lipidperoxides and aldehydes Moreover spices and herbs havebeen used for years for flavour aroma and color preserving[246] Dried fruits constitute a rich source of antioxidant phy-tochemicals (namely phenolics and carotenoids) and havebeen recently incorporated in fruit-based functional foodsNevertheless elaborated studies are still required for the val-idation of dried fruits benefits [247] Investigating improvedways for isolation of active phytocompounds and employingchemometrics in establishing the effective combinations ofspices or herb-sourced antioxidants is an increasing trendin view of the steady high quality requirements that led toconstant optimization of analytical techniques [246]

With respect to the analytical methodology the devel-opment of experimental conditions of the working protocols(that should be tuned to the nature of the sampletarget com-pound(s)) and also the interpretation of the results should becarefully considered A plethora of analytical methods wereapplied to total antioxidant capacity in plant extracts yetdifficulties may arise when it comes to choosing the mostadequate method It was stressed out that conditions natureof substrate and concentration of analysed antioxidantsshould be as close as possible to those encountered in foodor biological media [248] So the term antioxidant activity istightly related to the context of particular reaction conditions[44]

In the case of the radical scavenging antioxidants theantioxidant-radical reactivity (both rate constant and sto-ichiometry) antioxidant localization mobility in reactionmedia stability of the antioxidant-derived radical interre-lation with other antioxidants and metabolism should bemeasured to thoroughly understand their dynamic actionas antioxidants For instance vitamin E has been proven

to be an efficacious radical scavenger but it was assertedthat it possesses weak activity against lipid peroxidationby lipoxygenase Carotenoids are not efficient in radicaltrapping but they inhibit single oxygen-induced oxidation[249] In the presence of transition metal ions phenolicradical scavengers can even induce oxidative damage tolipids acting as prooxidants through the aryloxy radical Thelatter is formed during the reaction of the phenolics withCu(II) and can attack the lipid substrate [44] following aradicalicmechanism similar to the one described in Section 1

The choice of the appropriatemethod should be groundedon the biomolecules targeted during the oxidation process(lipids proteins and nucleic acids) A viable antioxidantprotocol necessitates the quantification of more than oneproperty relevant to either foods or biological systemsAntioxidant standardization is required to diminish the dis-crepancies that may result from only one technique appliedto antioxidant assessment [250]

A comparative discussion of the detection mechanismshould consider the following aspects Gas chromatographyallows separation and determination of a precise amountof certain antioxidants in different media HPLC as well asgas chromatography coupled to various detectors also resultsin detecting individual particular antioxidant compounds(ascorbic acid tocopherols flavonoids phenolic acids etc)These methods require qualification they are laborious butbenefit from most accurate and efficacious separation andquantitation [13 251] HPLC can provide limits of detectionand quantification of 04 and 12 ngmL such as for the case oflinalool 06 and 14 ngmL and geranyl acetate respectively[96]

With respect to the methods relying on optical detectionthe antioxidant activity is exerted by various mechanismsso the results furnished by a technique that relies solelyon one mechanism may not take account on the actualantioxidant activity value There are assays referring to var-ious oxygenatednitrogenated species methods appliable toboth lipophilic and hydrophilic antioxidants and techniquesrelying on either hydrogen transfer or single electron transfer[248] It has been assessed that the ones involving peroxylradical trapping are the most extensively applied (TRAPORAC beta-carotene bleaching and chemiluminescence) asthis radical species is prevalent in biologicalmediaNeverthe-less thesemethods relying on hydrogen atom transfer shouldbe corroboratedwith assays relying on single electron transfer(such asABTS quenching)On the other hand single electrontransfer-based methods rely on slow reactions that are sensi-tive to ascorbic acid uric acid and polyphenols Secondaryreactions are likely to occur which may lead to interferences[85 252] Among the spectrometric in vitro methods theirfrequency of application decreases in the order DPPH scav-enginggt hydroxyl radical scavenginggt superoxide dismutaseactivity gt beta-carotene linoleate bleaching Recently reliableresults have been obtained by combining in vitro method(DPPHassay)with high performance liquid chromatographySuch a DPPH-HPLC online assay especially for natural-sourced antioxidants requires minimum sample preparation[253] Moreover it allows hampering of the drawbacks ofthe simple DPPH technique that uses offline colorimetric


detection and for which the small changes in absorbancecannot be quantified [254] With respect to the in vivo tech-niques the lipid peroxidase assay is the most frequently usedfollowed by catalase and glutathione peroxidase [18 251]Thein vivo antioxidant capacity assay uses biological media [255]so the antioxidants usually undergo absorption transportdistribution and retention in the biological fluids cells andtissues As during these stepsmany alterations can occur (egbiotransformation during enzymatic conjugation) the exper-imental protocol has to be cautiously carried out [256 257]The discussion in vivo versus in vitro is of vital importance inthese types of assays as the antioxidant capacity of plants andphytocompounds is influenced by various parameters in vivosuch as gut absorption metabolism bioavailability and thepresence of other antioxidants or transition metal ions [50]and screening by in vitro assays should be complemented byin vivo efficacy testing [258] Moreover it has been stressedout that once the efficacy of a phytocompound is proven invivo the mechanisms of action should be subject to analysisin vitro to avoid discrepancies thatmay occurwhen validatingin vitro confirmed methods in vivo [50]

When it comes to the chemiluminescent assay the majorshortcoming is represented by light emission from othersources [13 251] The ORAC technique with fluorescentdetection relies on a mechanism regarded as biologicallypertinent as it takes account on the contribution of bothlipophilic and hydrophilic antioxidants [85]

Nevertheless inORACassay only the antioxidant activityagainst peroxyl radicals is measured disregarding the otherreactive oxygenated species It has been also asserted thatantioxidant molecules present in foodstuffs exert numerousfunctions some not related to the capacity to trap free radi-cals Also it has been considered that the values of antioxidantcapacity do not give account on all the effects of particularbioactive principles [259] The values of antioxidant capacityfurnished by in vitro studies cannot be extrapolated to invivo effects and the clinical trials testing benefits of dietaryantioxidants may result in mixed results Moreover it wasmentioned that ORAC values expressed as Trolox equivalentsgive account on both the inhibition time and the extentof oxidation inhibition Novel versions of the ORAC assayhave been developed which use other substrates as reference(eg gallic acid) which makes data comparison not an easytask These considerations led to ORAC withdrawal from theonline catalog of United States Department of Agriculture[259] So if ORAC assay is applied as a complementaryassay instrument in connection with other analytical tech-niques data comparison has to be performed using thesame standard clearly defined units of expressing the resultsdistinguishing between dried and fresh foods and juicesor other processed foods Measuring in vitro antioxidantproperties remains useful as far as the benefits are also relatedto what happens outside human body

The type of the prevalent antioxidant class present orthe reference antioxidant chosen plays important roles withrespect to the correlation of results obtained by differentspectrometric methods in the case of guava fruit methanolextract the ABTS DPPH FRAP and ORAC methods gaveclose results The antioxidant activity of methanol extract

exhibited good correlation with ascorbic acid or total phe-nolics with best correlation being shown by FRAP resultswith both ascorbic acid and total phenolic content On theother hand ABTS DPPH and FRAP results for methanolicextracts were negatively correlated with total carotenoidsThe antioxidant capacity of dichloromethane extract (thattook account on lipophilic antioxidants) was low comparedto antioxidant activity of methanol extract So hydrophilicascorbic acid and phenolics have been proven to be the maincontributors to antioxidant capacity of guava fruit [260]In Folin-Ciocalteu total phenol assay it has been assessedthat some nonphenolic compounds (eg ascorbic acid) thatcan transfer electrons to phosphomolybdicphosphotungsticcomplex in alkaline media may interfere with the resultsThis shortcoming can be minimized by extraction with 95methanol applied to plant tissue [261]

Several correlations have been reported between theresults obtained at the application of DPPH∙ ABTS∙+ andFRAP and total polyphenol content assays as follows posi-tive correlation between TPC-DPPH∙ (08277) TPC-ABTS∙+(08835) and TPC-FRAP (09153) [262] Also correlationshave been established between the antioxidant capacity val-ues reported to different standard antioxidants the ABTS∙+antioxidant capacities of basil in 57 ethanol extract were4727 plusmn 216mg Trolox equivalentsg DW or 3117 plusmn 142mgascorbic acid equivalentsgDW(white holy basil) and 6586plusmn551mg Trolox equivalentsg DW or 4343 plusmn 363mg ascorbicacid equivalentsg DW (red holy basil) The DPPH∙ valuesof 57 ethanol extract of basil were also expressed as perreference to different standards 541 plusmn 004mg Trolox equiv-alentsg DW or 459 plusmn 003mg ascorbic equivalentsg DW(white holy basil) and 623 plusmn 019mg Trolox equivalentsgDW or 528 plusmn 016mg ascorbic equivalentsg DW (red holybasil) [263] The higher values furnished by ABTS∙+ assaywere explained by the fact that compounds which haveABTS∙+ scavenging activitymay not be endowedwithDPPH∙scavenging potential [264] Moreover it was found that someproducts of ABTS∙+ scavenging reaction may exert a higherantioxidant capacity than the antioxidants initially present inthe reaction medium and can react with ABTS∙+ [265]

The results of total antioxidant capacity assay of yerbamate (Ilex paraguariensis) ethanol extracts evaluated byDPPH∙ method were expressed as ascorbic acid equivalentsor Trolox equivalents (in mass percentage g dry matter)trying to facilitate a comparative assessment 128ndash231 gTrolox equivalents dry matter and 91ndash164 g ascorbic acidequivalents dry matter [266]

Rapidity lower cost simpler instrumentation and oxi-dation potential value of each particular sample componentevaluated with the same accuracy (irrespective of the antioxi-dant potency in conditions of efficient peak separation) arereported advantages of electroanalysis versus spectropho-tometry It was asserted that in DPPH∙ photometry theabsorbance variations can be subject to more inaccuracywhereas in voltammetry deviations in the peak potentialvalue smaller than plusmn3mV were noticed Therefore in pho-tocolorimetry at low antioxidant capacity values the resultsmay be prone to a greater uncertainty [267] Moreover insuch spectrophotometric assays there can be compounds


other than antioxidants that can contribute to the measuredanalytical signal at the respective wavelength

Nevertheless in the case of samples rich in variousphenolic classes and possessing different electrooxidationpotentials (eg wines) 119876500 value as analytical signal doesnot give account on less oxidizable components such asphenolics with more elevated oxidation potentials (eg800mV) [268 269] Step voltammetric methods like dif-ferential pulse or square wave voltammetry have improvedresolution versus linear sweepingmethods (cyclic technique)as charging current is minimized [269] In differential pulsevoltammetric polyphenol assessment the results exhibiteda tight correlation with the antioxidant activities furnishedby photocolorimetry [154] Excellent sensitivity is obtainedat caffeic acid stripping voltammetric assessment operatingin square wave mode a detection limit of 4 times 10minus9molLin acetate buffer pH = 40 [93] Amperometric biosen-sors have the advantage of enzyme specificity accuracyand fastness imparted by electrochemical detection Thedrawback of difficultly electrooxidizing high molecular massantioxidants at fixed potential can be solved by changingthe biocatalyst or by the use of mediators that diminishthe working potential [269 270] Biamperometric techniquesprovide enhanced selectivity that depends on the specificityof the reaction involving the antioxidant and the oxidizedform of the redox couple [158 271] The potential valueimposed should be strictly controlled since an increase of thelatter could lead to interference of electroactive compoundsother than antioxidants that might react at the electrode[272]

Employing minimum two analytical techniques (rely-ing on different mechanisms) and applying three sampledilutions are generally recommended [273 274] Hence arigorous evaluation of antioxidant capacity should not berestricted to a simple antioxidant test and should consider thevariability factors that influence the final value for instancethe consistency between phenolic content and antioxidantcapacity assessed aswell as the techniquesrsquo performances hasbeen proven to be dependent on the nature of the sampleits composition and pH (the latter imparting the existenceof protonated or deprotonated form of biocompounds)extraction and analytical method applied It was concludedthat several test procedures may be necessary to ensure viableantioxidant activity results [3]

Researches focusing on free radicals plant extracts plant-derived antioxidants in foodstuffs and biological mediashould be accompanied by validation of biological markersmeant to define the efficacy of antioxidant compounds in diet[275] The comparative evaluation of antioxidant potentialsreported by different laboratories should consider the signifi-cant differences in sample pretreatment extraction and finalvalue expression mode [276]

Competing Interests

The authors declare that there are no competing interestsregarding the publication of this paper

References

[1] V RWinrow P GWinyard C J Morris and D R Blake ldquoFreeradicals in inflammation second messengers and mediators oftissue destructionrdquo British Medical Bulletin vol 49 no 3 pp506ndash522 1993

[2] B Poljsak D Suput and I Milisav ldquoAchieving the balancebetween ROS and antioxidants when to use the syntheticantioxidantsrdquo Oxidative Medicine and Cellular Longevity vol2013 Article ID 956792 11 pages 2013

[3] M Antolovich P D Prenzler E Patsalides S McDonald andK Robards ldquoMethods for testing antioxidant activityrdquo Analystvol 127 no 1 pp 183ndash198 2002

[4] R Shenoy and A Shirwaikar ldquoAnti inflammatory and freeradical scavenging studies of Hyptis suaveolens (Labiatae)rdquoIndian Drugs vol 39 no 11 pp 574ndash577 2002

[5] P Evans and B Halliwell ldquoFree radicals and hearing causeconsequence and criteriardquo Annals of the New York Academy ofSciences vol 884 pp 19ndash40 1999

[6] T P A Devasagayam and P C Kesavan ldquoRadioprotectiveand antioxidant action of caffeine mechanistic considerationsrdquoIndian Journal of Experimental Biology vol 34 no 4 pp 291ndash297 1996

[7] A V Badarinath K Mallikarjuna Rao C Madhu SudhanaChetty S Ramkanth T V S Rajan and K Gnanaprakash ldquoAreview on In-vitro antioxidant methods comparisions corre-lations and considerationsrdquo International Journal of PharmTechResearch vol 2 no 2 pp 1276ndash1285 2010

[8] V Lobo A Phatak and N Chandra ldquoFree radicals andfunctional foods Impact on human healthrdquo PharmacognosyReviews vol 4 pp 118ndash126 2010

[9] M Dizdaroglu P Jaruga M Birincioglu and H RodriguezldquoFree radical-induced damage to DNA mechanisms and mea-surementrdquo Free Radical Biology andMedicine vol 32 no 11 pp1102ndash1115 2002

[10] M Valko M Izakovic M Mazur C J Rhodes and J TelserldquoRole of oxygen radicals inDNAdamage and cancer incidencerdquoMolecular and Cellular Biochemistry vol 266 no 1-2 pp 37ndash562004

[11] L Benov andA F Beema ldquoSuperoxide-dependence of the shortchain sugars-induced mutagenesisrdquo Free Radical Biology andMedicine vol 34 no 4 pp 429ndash433 2003

[12] B Halliwell and S Chirico ldquoLipid peroxidation its mechanismmeasurement and significancerdquoThe American Journal of Clini-cal Nutrition vol 57 no 5 pp 715ndash724 1993

[13] M Carocho and I C F R Ferreira ldquoA review on antioxidantsprooxidants and related controversy natural and syntheticcompounds screening and analysis methodologies and futureperspectivesrdquo Food and Chemical Toxicology vol 51 no 1 pp15ndash25 2013

[14] C Lopez-Alarcon and A Denicola ldquoEvaluating the antioxidantcapacity of natural products a review on chemical and cellular-based assaysrdquo Analytica Chimica Acta vol 763 pp 1ndash10 2013

[15] D P Jones ldquoRedefining oxidative stressrdquo Antioxidants andRedox Signaling vol 8 no 9-10 pp 1865ndash1879 2006

[16] JW Finley A-N Kong K J Hintze E H Jeffery L L Ji and XG Lei ldquoAntioxidants in foods state of the science important tothe food industryrdquo Journal of Agricultural and Food Chemistryvol 59 no 13 pp 6837ndash6846 2011

[17] A M Pisoschi and A Pop ldquoThe role of antioxidants in thechemistry of oxidative stress a reviewrdquo European Journal ofMedicinal Chemistry vol 97 pp 55ndash74 2015


[18] M N Alam N J Bristi and M Rafiquzzaman ldquoReview on invivo and in vitro methods evaluation of antioxidant activityrdquoSaudi Pharmaceutical Journal vol 21 no 2 pp 143ndash152 2013

[19] V L Kinnula and J D Crapo ldquoSuperoxide dismutases inmalignant cells and human tumorsrdquo Free Radical Biology andMedicine vol 36 no 6 pp 718ndash744 2004

[20] U Singh and I Jialal ldquoOxidative stress and atherosclerosisrdquoPathophysiology vol 13 no 3 pp 129ndash142 2006

[21] K Sas H Robotka J Toldi and L Vecsei ldquoMitochondriametabolic disturbances oxidative stress and the kynureninesystem with focus on neurodegenerative disordersrdquo Journal ofthe Neurological Sciences vol 257 no 1-2 pp 221ndash239 2007

[22] M A Smith C A Rottkamp A Nunomura A K Raina andG Perry ldquoOxidative stress in Alzheimerrsquos diseaserdquo Biochimica etBiophysica Acta vol 1502 no 1 pp 139ndash144 2000

[23] I Guidi D Galimberti S Lonati et al ldquoOxidative imbalancein patients with mild cognitive impairment and AlzheimerrsquosdiseaserdquoNeurobiology of Aging vol 27 no 2 pp 262ndash269 2006

[24] J L Bolton M A Trush T M Penning G Dryhurst and T JMonks ldquoRole of quinones in toxicologyrdquo Chemical Research inToxicology vol 13 no 3 pp 135ndash160 2000

[25] G E Arteel ldquoOxidants and antioxidants in alcohol-inducedliver diseaserdquo Gastroenterology vol 124 no 3 pp 778ndash7902003

[26] B S Ramakrishna R Varghese S Jayakumar M Mathan andK A Balasubramanian ldquoCirculating antioxidants in ulcerativecolitis and their relationship to disease severity and activityrdquoJournal of Gastroenterology and Hepatology vol 12 no 7 pp490ndash494 1997

[27] JMUpston L Kritharides andR Stocker ldquoThe role of vitaminE in atherosclerosisrdquoProgress in Lipid Research vol 42 no 5 pp405ndash422 2003

[28] D-H Hyun J O Hernandez M P Mattson and R de CaboldquoThe plasmamembrane redox system in agingrdquoAgeing ResearchReviews vol 5 no 2 pp 209ndash220 2006

[29] H Yin L Xu and N A Porter ldquoFree radical lipid peroxidationMechanisms and analysisrdquoChemical Reviews vol 111 no 10 pp5944ndash5972 2011

[30] R J Hamilton ldquoThe chemistry of rancid foodsrdquo in Rancidity inFoods J C Allen and R J Hamilton Eds pp 1ndash20 AppliedScience Publishers London UK 1983

[31] J Kanner J B German and J E Kinsella ldquoInitiation of lipidperoxidation in biological systemsrdquo Critical Reviews in FoodScience and Nutrition vol 25 no 4 pp 317ndash364 1987

[32] K H Cheeseman and T F Slater ldquoAn introduction to freeradical biochemistryrdquo British Medical Bulletin vol 49 no 3 pp481ndash493 1993

[33] DMartysiak-Zurowska andWWenta ldquoA comparison of ABTSand DPPHmethods for assessing the total antioxidant capacityof human milkrdquo Acta Scientiarum Polonorum TechnologiaAlimentaria vol 11 no 1 pp 83ndash89 2012

[34] E B Rimm A Ascherio E Giovannucci D Spiegelman M JStampfer and W C Willett ldquoVegetable fruit and cereal fiberintake and risk of coronary heart disease among menrdquo Journalof the AmericanMedical Association vol 275 no 6 pp 447ndash4511996

[35] E B Rimm M B Katan A Ascherio M J Stampfer and WC Willett ldquoRelation between intake of flavonoids and risk forcoronary heart disease in male health professionalsrdquo Annals ofInternal Medicine vol 125 no 5 pp 384ndash389 1996

[36] M V Eberhardt C Y Lee and R H Liu ldquoAntioxidant activityof fresh applesrdquo Nature vol 405 no 6789 pp 903ndash904 2000

[37] K Ganesan K S Kumar and P V S Rao ldquoComparativeassessment of antioxidant activity in three edible species ofgreen seaweed Enteromorpha from Okha northwest coast ofIndiardquo Innovative Food Science and Emerging Technologies vol12 no 1 pp 73ndash78 2011

[38] A M Pisoschi Food Additives and Ingredients-Structures Prop-erties Uses Elisavaros Edition Bucharest Romania 2012

[39] R Stan Food AdditivesmdashNatural and Synthetic Products Print-ech Bucharest Romania 2007

[40] E A Shalaby and S M M Shanab ldquoAntioxidant compoundsassays of determination and mode of actionrdquo African Journal ofPharmacy and Pharmacology vol 7 no 10 pp 528ndash539 2013

[41] K Rahman ldquoStudies on free radicals antioxidants and co-factorsrdquo Clinical Invervention in Aging vol 2 pp 219ndash236 2007

[42] P E Gamble and J J Burke ldquoEffect of water stress on thechloroplast antioxidant systemrdquo Plant Physiology vol 76 no 3pp 615ndash621 1984

[43] D V Ratnam D D Ankola V Bhardwaj D K Sahana andM N V R Kumar ldquoRole of antioxidants in prophylaxis andtherapy a pharmaceutical perspectiverdquo Journal of ControlledRelease vol 113 no 3 pp 189ndash207 2006

[44] D Gupta ldquoMethods for determination of antioxidant capacitya reviewrdquo International Journal of Pharmaceutical Sciences andResearch vol 6 pp 546ndash566 2015

[45] P Rajendran N Nandakumar T Rengarajan et al ldquoAntioxi-dants and human diseasesrdquo Clinica Chimica Acta vol 436 pp332ndash347 2014

[46] S Chand and R Dave ldquoIn vitro models for antioxidant activ-ity evaluation and some medicinal plants possessing antioxi-dant properties an overviewrdquo African Journal of MicrobiologyResearch vol 3 pp 981ndash996 2009

[47] S Ahmad M A Arshad S Ijaz U Khurshid F Rashid andR Azam ldquoReview on methods used to determine antioxidantactivityrdquo International Journal of Multidisciplinary Research andDevelopment vol 1 pp 35ndash40 2014

[48] R G Alscher J L Donahue and C L Cramer ldquoReactiveoxygen species and antioxidants relationships in green cellsrdquoPhysiologia Plantarum vol 100 no 2 pp 224ndash233 1997

[49] CH Foyer andGNoctor ldquoRedox homeostasis and antioxidantsignaling a metabolic interface between stress perception andphysiological responsesrdquoThe Plant Cell vol 17 no 7 pp 1866ndash1875 2005

[50] D M Kasote S S Katyare M V Hegde and H Bae ldquoSig-nificance of antioxidant potential of plants and its relevanceto therapeutic applicationsrdquo International Journal of BiologicalSciences vol 11 no 8 pp 982ndash991 2015

[51] M-H Yang H-J Lin and Y-M Choong ldquoA rapid gas chro-matographic method for direct determination of BHA BHTand TBHQ in edible oils and fatsrdquo Food Research Internationalvol 35 no 7 pp 627ndash633 2002

[52] RM Smith ldquoBefore the injectionmdashmodernmethods of samplepreparation for separation techniquesrdquo Journal of Chromatogra-phy A vol 1000 no 1-2 pp 3ndash27 2003

[53] M D Luque de Castro and L E Garcıa-Ayuso ldquoSoxhletextraction of solid materials an outdated technique with apromising innovative futurerdquo Analytica Chimica Acta vol 369no 1-2 pp 1ndash10 1998

[54] J Azmir I S M Zaidul M M Rahman et al ldquoTechniquesfor extraction of bioactive compounds from plant materials a


reviewrdquo Journal of Food Engineering vol 117 no 4 pp 426ndash4362013

[55] A Gupta M Naraniwal and V Kothari ldquoModern extractionmethods for preparation of bioactive plant extractsrdquo Interna-tional Journal of Applied and Natural Sciences vol 1 pp 8ndash262012

[56] S S Handa ldquoAn overview of extraction techniques for medici-nal and aromatic plantsrdquo in Extraction Technologies for Medici-nal and Aromatic Plants Scientific S S Handa S P S KhanujaG Longo and D D Rakesh Eds chapter 1 pp 21ndash52United Nations Industrial Development Organization and theInternational Centre for Science and High Technology TriesteItaly 2008

[57] P S Vankar ldquoEssential oils and fragrances from natural sour-cesrdquo Resonance vol 9 no 4 pp 30ndash41 2004

[58] L V Silva D L Nelson M F B Drummond L Dufosse andM B A Gloria ldquoComparison of hydrodistillation methods forthe deodorization of turmericrdquo Food Research International vol38 no 8-9 pp 1087ndash1096 2005

[59] J Inczedy T Lengyel and A M Ure ldquoSupercritical fluidchromatography and extractionrdquo in Compendium of AnalyticalNomenclature Definitive Rules 1997 Blackwell Science OxfordUK 3rd edition 1998 httpchemanalyticacombooknovyyspravochnik khimika i tekhnologa02 analiticheskaya khim-iya chast I4690

[60] M Sihvonen E Jarvenpaa V Hietaniemi and R HuopalahtildquoAdvances in supercritical carbon dioxide technologiesrdquo Trendsin Food Science and Technology vol 10 no 6-7 pp 217ndash2221999

[61] J J R Pare J M R Belanger and S S Stafford ldquoMicrowave-assisted process (MAP) a new tool for the analytical labora-toryrdquo TrAC Trends in Analytical Chemistry vol 13 pp 176ndash1841994

[62] M Letellier and H Budzinski ldquoMicrowave assisted extractionof organic compoundsrdquo Analusis vol 27 no 3 pp 259ndash2701999

[63] T Jain ldquoMicrowave assisted extraction for phytoconstituentsmdashan overviewrdquo Asian Journal of Research in Chemistry vol 2 pp19ndash25 2009

[64] S Ahuja and D Diehl ldquoSampling and sample preprationrdquo inComprehensive Analytical Chemistry S Ahuja andN JespersenEds vol 47 chapter 2 pp 15ndash40 Elsevier Oxford UK 2006

[65] G Cravotto L Boffa S Mantegna P Perego M Avogadro andP Cintas ldquoImproved extraction of vegetable oils under high-intensity ultrasound andor microwavesrdquo Ultrasonics Sono-chemistry vol 15 no 5 pp 898ndash902 2008

[66] A Alupului I Calinescu and V Lavric ldquoMicrowave extractionof active principles from medicinal plantsrdquo UPB ScientificBulletin Series B Chemistry and Materials Science vol 74 no2 pp 129ndash142 2012

[67] M C Herrera and M D Luque De Castro ldquoUltrasound-assisted extraction for the analysis of phenolic compounds instrawberriesrdquo Analytical and Bioanalytical Chemistry vol 379no 7-8 pp 1106ndash1112 2004

[68] T J Mason L Paniwnyk and J P Lorimer ldquoThe uses ofultrasound in food technologyrdquo Ultrasonics Sonochemistry vol3 no 3 pp S253ndashS260 1996

[69] M G Cares Y Vargas L Gaete J Sainz and J AlarconldquoUltrasonically assisted extraction of bioactive principles fromQuillaja SaponariaMolinardquo Physics Procedia vol 3 pp 169ndash1782009

[70] A H Metherel A Y Taha H Izadi and K D Stark ldquoTheapplication of ultrasound energy to increase lipid extractionthroughput of solid matrix samples (flaxseed)rdquo ProstaglandinsLeukotrienes and Essential Fatty Acids vol 81 no 5-6 pp 417ndash423 2009

[71] A Bouakaz ldquoSonoporation concept and mechanismsrdquo inTherapeutic Ultrasound J-M Escoffre and A Bouakaz Edsvol 10 pp 175ndash189 Springer Basel Switzerland 2016

[72] M Savova H J Bart and I Seikova ldquoEnhancement of masstransfer in solid-liquid extraction by pulsed electric fieldrdquoJournal of the University of Chemical Technology andMetallurgyvol 40 pp 251ndash255 2005

[73] V Heinz S Toepfl and D Knorr ldquoImpact of temperature onlethality and energy efficiency of apple juice pasteurization bypulsed electric fields treatmentrdquo Innovative Food Science andEmerging Technologies vol 4 no 2 pp 167ndash175 2003

[74] N Lopez E Puertolas S Condon I Alvarez and J RasoldquoEffects of pulsed electric fields on the extraction of phenoliccompounds during the fermentation of must of Tempranillograpesrdquo Innovative Food Science and Emerging Technologies vol9 no 4 pp 477ndash482 2008

[75] N Lopez E Puertolas S Condon J Raso and I AlvarezldquoEnhancement of the extraction of betanine from red beetrootby pulsed electric fieldsrdquo Journal of Food Engineering vol 90no 1 pp 60ndash66 2009

[76] A Rosenthal D L Pyle and K Niranjan ldquoAqueous andenzymatic processes for edible oil extractionrdquo Enzyme andMicrobial Technology vol 19 no 6 pp 402ndash420 1996

[77] R K Singh B C Sarker B K Kumbhar Y C Agrawal and MK Kulshreshtha ldquoResponse surface analysis of enzyme assistedoil extraction factors for sesame groundnut and sunflowerseedsrdquo Journal of Food Science and Technology vol 36 no 6pp 511ndash514 1999

[78] S Latif and F Anwar ldquoPhysicochemical studies of hemp(Cannabis sativa) seed oil using enzyme-assisted cold-pressingrdquoEuropean Journal of Lipid Science and Technology vol 111 no 10pp 1042ndash1048 2009

[79] K Niranjan and P Hanmoungjai ldquoEnzyme-aided aquousextractionrdquo in Nutritionally Enhanced Edible Oil Processing NT Dunford and H B Dunford Eds AOCS Champaign IllUSA 2004

[80] H Domınguez M J Nunez and J M Lema ldquoEnzyme-assistedhexane extraction of soya bean oilrdquo Food Chemistry vol 54 no2 pp 223ndash231 1995

[81] M Puri D Sharma and C J Barrow ldquoEnzyme-assisted extrac-tion of bioactives from plantsrdquo Trends in Biotechnology vol 30no 1 pp 37ndash44 2012

[82] J Concha C Soto R Chamy and M E Zuniga ldquoEnzymaticpretreatment on rose-hip oil extraction hydrolysis and pressingconditionsrdquo Journal of the American Oil Chemistsrsquo Society vol81 no 6 pp 549ndash552 2004

[83] E Ibanez M Herrero J A Mendiola and M Castro-PuyanaldquoExtraction and characterization of bioactive compounds withhealth benefits from marine resources macro and micro algaecyanobacteria and invertebratesrdquo in Marine Bioactive Com-pounds Sources Characterization and Applications M HayesEd pp 55ndash98 Springer 2012

[84] L D Mello and L T Kubota ldquoBiosensors as a tool for theantioxidant status evaluationrdquo Talanta vol 72 no 2 pp 335ndash348 2007

[85] R L Prior X Wu and K Schaich ldquoStandardized methodsfor the determination of antioxidant capacity and phenolics


in foods and dietary supplementsrdquo Journal of Agricultural andFood Chemistry vol 53 no 10 pp 4290ndash4302 2005

[86] A Jimenez A Selga J L Torres and L Julia ldquoReducing activityof polyphenols with stable radicals of the TTM series Electrontransfer versusH-abstraction reactions in flavan-3-olsrdquoOrganicLetters vol 6 no 24 pp 4583ndash4586 2004

[87] J Wang Y-D Yue F Tang and J Sun ldquoTLC screening forantioxidant activity of extracts from fifteen bamboo species andidentification of antioxidant flavone glycosides from leaves ofBambusa textilisMcClurerdquoMolecules vol 17 no 10 pp 12297ndash12311 2012

[88] R A KhanM R Khan S Sahreen andMAhmed ldquoEvaluationof phenolic contents and antioxidant activity of various solventextracts of Sonchus asper (L) Hillrdquo Chemistry Central Journalvol 6 no 1 article 12 2012

[89] A M Pisoschi A Pop G P Negulescu and A PisoschildquoDetermination of ascorbic acid content of some fruit juicesand wine by voltammetry performed at pt and carbon pasteelectrodesrdquoMolecules vol 16 no 2 pp 1349ndash1365 2011

[90] S Anandjiwala H Srinivasa J Kalola and M Rajani ldquoFree-radical scavenging activity of Bergia suffruticosa (Delile) FenzlrdquoJournal of Natural Medicines vol 61 no 1 pp 59ndash62 2007

[91] W Jesionek B Majer-Dziedzic and I M Choma ldquoSeparationidentification and investigation of antioxidant ability of plantextract components using TLC LCndashMS and TLCndashDPPH∙rdquoJournal of Liquid Chromatography and Related Technologies vol38 no 11 pp 1147ndash1153 2015

[92] S K Sadhu F Ahmed T Ohtsuki and M IshibashildquoFlavonoids from Sonneratia caseolarisrdquo Journal of NaturalMedicines vol 60 no 3 pp 264ndash265 2006

[93] K Tyszczuk A Skalska-Kaminska and A Wozniak ldquoVoltam-metricmethod using a lead film electrode for the determinationof caffeic acid in a plant materialrdquo Food Chemistry vol 125 no4 pp 1498ndash1503 2011

[94] WWankhar S Srinivasan and S Rathinasamy ldquoHPTLC analy-sis of Scoparia dulcis Linn (Scrophulariaceae) and its larvicidalpotential against dengue vector Aedes aegyptirdquoNatural ProductResearch vol 29 no 18 pp 1757ndash1760 2015

[95] S M F Freire A J S Emim A J Lapa C Souccar and L MB Torres ldquoAnalgesic and antiinflammatory properties of Sco-paria dulcis L Extracts and glutinol in rodentsrdquo PhytotherapyResearch vol 7 no 6 pp 408ndash414 1993

[96] K Singh R Rani P Bansal S Medhe and M M SrivastavaldquoAntioxidant activity of essential oil ofCoriandrum sativum andstandardization of HPTLC method for the estimation of majorphytomarkersrdquo Journal of Analytical Chemistry vol 70 no 2pp 220ndash224 2015

[97] M A Hossain M D Shah and M Sakari ldquoGas chromatog-raphy-mass spectrometry analysis of various organic extractsof Merremia borneensis from Sabahrdquo Asian Pacific Journal ofTropical Medicine vol 4 no 8 pp 637ndash641 2011

[98] M A Hossain K M ALsabari A M Weli and Q Al-RiyamildquoGas chromatographyndashmass spectrometry analysis and totalphenolic contents of various crude extracts from the fruits ofDatura metel Lrdquo Journal of Taibah University for Science vol 7no 4 pp 209ndash215 2013

[99] R AMothanaM S Alsaid S S Hasoon NMAl-Mosaiy A JAl-Rehaily andMA Al-Yahya ldquoAntimicrobial and antioxidantactivities and gas chromatographymass spectrometry (GCMS)analysis of the essential oils of Ajuga bracteosa Wall ex Benthand Lavandula dentata L growing wild in Yemenrdquo Journal ofMedicinal Plants Research vol 6 no 15 pp 3066ndash3071 2012

[100] E-H Liu P Zhao L Duan et al ldquoSimultaneous determinationof six bioactive flavonoids in Citri Reticulatae Pericarpium byrapid resolution liquid chromatography coupled with triplequadrupole electrospray tandem mass spectrometryrdquo FoodChemistry vol 141 no 4 pp 3977ndash3983 2013

[101] M Stankevicius I Akuaeca I Jakobsone and A MaruskaldquoComparative analysis of radical scavenging and antioxidantactivity of phenolic compounds present in everyday use spiceplants by means of spectrophotometric and chromatographicmethodsrdquo Journal of Separation Science vol 34 no 11 pp 1261ndash1267 2011

[102] S SahreenM R Khan R A Khan andNA Shah ldquoEstimationof flavoniods antimicrobial antitumor and anticancer activityof Carissa opaca fruitsrdquo BMC Complementary and AlternativeMedicine vol 13 article 372 2013

[103] A DjeridaneM Yousfi B Nadjemi N Vidal J F Lesgards andP Stocker ldquoScreening of some Algerianmedicinal plants for thephenolic compounds and their antioxidant activityrdquo EuropeanFood Research and Technology vol 224 no 6 pp 801ndash809 2007

[104] O Yesil-Celiktas G Girgin H Orhan H J Wichers E Bedirand F Vardar-Sukan ldquoScreening of free radical scavengingcapacity and antioxidant activities of Rosmarinus officinalisextracts with focus on location and harvesting timesrdquo EuropeanFood Research and Technology vol 224 no 4 pp 443ndash451 2007

[105] G-F Deng X-R Xu Y-J Guo et al ldquoDetermination of antiox-idant property and their lipophilic and hydrophilic phenoliccontents in cereal grainsrdquo Journal of Functional Foods vol 4no 4 pp 906ndash914 2012

[106] V Ani M C Varadaraj and K Akhilender Naidu ldquoAntioxidantand antibacterial activities of polyphenolic compounds frombitter cumin (Cuminum nigrum L)rdquo European Food Researchand Technology vol 224 no 1 pp 109ndash115 2006

[107] M Kosar A Altintas N Kirimer and K H C Baser ldquoDetermi-nation of the free radical scavenging activity of LyciumextractsrdquoChemistry of Natural Compounds vol 39 no 6 pp 531ndash5352003

[108] C Carkeet B A Clevidence and J A Novotny ldquoAnthocyaninexcretion by humans increases linearly with increasing straw-berry doserdquoThe Journal of Nutrition vol 138 no 5 pp 897ndash9022008

[109] D Benedec L Vlase D Hanganu and I Oniga ldquoAntioxidantpotential and polyphenolic content of Romanian Ocimumbasilicumrdquo Digest Journal of Nanomaterials and Biostructuresvol 7 no 3 pp 1263ndash1270 2012

[110] S A V Eremia G-L Radu and S-C Litescu ldquoMonitoring ofrosmarinic acid accumulation in sage cell cultures using laccasebiosensorrdquo Phytochemical Analysis vol 24 no 1 pp 53ndash582013

[111] M Kurzawa A Filipiak-Szok E Kłodzinska and E SzłykldquoDetermination of phytochemicals antioxidant activity andtotal phenolic content in Andrographis paniculata using chro-matographicmethodsrdquo Journal of ChromatographyBAnalyticalTechnologies in the Biomedical and Life Sciences vol 995-996pp 101ndash106 2015

[112] X Lin Y Ni and S Kokot ldquoGlassy carbon electrodes modifiedwith gold nanoparticles for the simultaneous determination ofthree food antioxidantrdquo Analytica Chimica Acta vol 765 pp54ndash62 2013

[113] I B Rebey S Kefi S Bourgou et al ldquoRipening stage andextraction method effects on physical properties polyphenolcomposition and antioxidant activities of cumin (Cuminum


cyminum L) Seedsrdquo Plant Foods for Human Nutrition vol 69no 4 pp 358ndash364 2014

[114] H-C SeoM SuzukiMOhnishi-Kameyama et al ldquoExtractionand identification of antioxidant components from Artemisiacapillaris herbardquo Plant Foods for Human Nutrition vol 58 no3 pp 1ndash12 2003

[115] P K Boniface M Singh S Verma et al ldquoRP-HPLC-DADmethod for the identification of two potential antioxidantagents namely verminoside and 1-O-(E)-caffeoyl-120573-gentiobiosefrom Spathodea campanulata leavesrdquoNatural Product Researchvol 29 no 7 pp 676ndash680 2015

[116] J Borowski A Szajdek E J Borowska E Ciska and HZielinski ldquoContent of selected bioactive components andantioxidant properties of broccoli (Brassica oleracea L)rdquo Euro-pean Food Research and Technology vol 226 no 3 pp 459ndash4652008

[117] A A Al-Amiery A A H Kadhum H R Obayes and AB Mohamad ldquoSynthesis and antioxidant activities of novel5-chlorocurcumin complemented by semiempirical calcula-tionsrdquo Bioinorganic Chemistry and Applications vol 2013 Arti-cle ID 354982 7 pages 2013

[118] M Leopoldini T Marino N Russo and M Toscano ldquoAntiox-idant properties of phenolic compounds H-atom versus elec-tron transfer mechanismrdquo Journal of Physical Chemistry A vol108 no 22 pp 4916ndash4922 2004

[119] B D Craft A L Kerrihard R Amarowicz and R B PeggldquoPhenol-based antioxidants and the in vitro methods used fortheir assessmentrdquo Comprehensive Reviews in Food Science andFood Safety vol 11 no 2 pp 148ndash173 2012

[120] D Huang O U Boxin and R L Prior ldquoThe chemistry behindantioxidant capacity assaysrdquo Journal of Agricultural and FoodChemistry vol 53 no 6 pp 1841ndash1856 2005

[121] E Klein and V Lukes ldquoDFTB3LYP study of the substituenteffect on the reaction enthalpies of the individual steps of singleelectron transfer-proton transfer and sequential proton losselectron transfer mechanisms of phenols antioxidant actionrdquoJournal of Physical Chemistry A vol 110 no 44 pp 12312ndash123202006

[122] A Urbaniak M Molski and M Szeląg ldquoQuantum-chemicalcalculations of the antioxidant properties of trans-p-coumaricacid and trans-sinapinic acidrdquo Computational Methods in Sci-ence and Technology vol 18 no 2 pp 117ndash128 2012

[123] M Karamac ldquoChelation of Cu(II) Zn(II) and Fe(II) by tanninconstituents of selected edible nutsrdquo International Journal ofMolecular Sciences vol 10 no 12 pp 5485ndash5497 2009

[124] L S Al HashmiM A Hossain AMWeli Q Al-Riyami and JN AlSabahi ldquoGas chromatography-mass spectrometry analysisof different organic crude extracts from the local medicinalplant of Thymus vulgaris Lrdquo Asian Pacific Journal of TropicalBiomedicine vol 3 no 1 pp 69ndash73 2013

[125] W Brand-Williams M E Cuvelier and C Berset ldquoUse of a freeradical method to evaluate antioxidant activityrdquo LWTmdashFoodScience and Technology vol 28 no 1 pp 25ndash30 1995

[126] P Molyneux ldquoThe use of the stable free radical diphenylpicryl-hydrazyl (DPPH) for estimating antioxidant activityrdquo Songk-lanakarin Journal of Science and Technology vol 26 pp 211ndash2192004

[127] R Re N Pellegrini A Proteggente A PannalaM Yang andCRice-Evans ldquoAntioxidant activity applying an improved ABTSradical cation decolorization assayrdquo Free Radical Biology andMedicine vol 26 no 9-10 pp 1231ndash1237 1999

[128] V Fogliano V Verde G Randazzo and A Ritieni ldquoMethod formeasuring antioxidant activity and its application to monitor-ing the antioxidant capacity of winesrdquo Journal of Agriculturaland Food Chemistry vol 47 no 3 pp 1035ndash1040 1999

[129] I F F Benzie and J J Strain ldquoThe ferric reducing ability ofplasma (FRAP) as a measure of lsquoantioxidant powerrsquo The FRAPassayrdquo Analytical Biochemistry vol 239 no 1 pp 70ndash76 1996

[130] M Oyaizu ldquoStudies on products of browning reaction Antiox-idative activities of products of browning reaction preparedfrom glucosaminerdquo The Japanese Journal of Nutrition andDietetics vol 44 no 6 pp 307ndash315 1986

[131] R Apak K Guclu M Ozyurek and S E Karademir ldquoNoveltotal antioxidant capacity index for dietary polyphenols andvitamins C and E using their cupric ion reducing capabilityin the presence of neocuproine CUPRAC methodrdquo Journal ofAgricultural and Food Chemistry vol 52 no 26 pp 7970ndash79812004

[132] R Apak K Guclu M Ozyurek and S E Celik ldquoMechanismof antioxidant capacity assays and the CUPRAC (cupric ionreducing antioxidant capacity) assayrdquo Microchimica Acta vol160 no 4 pp 413ndash419 2008

[133] P Prieto M Pineda and M Aguilar ldquoSpectrophotometricquantitation of antioxidant capacity through the formation ofa phosphomolybdenum complex specific application to thedetermination of vitamin Erdquo Analytical Biochemistry vol 269no 2 pp 337ndash341 1999

[134] S Shobana and K A Naidu ldquoAntioxidant activity of selectedIndian spicesrdquo Prostaglandins Leukotrienes and Essential FattyAcids vol 62 no 2 pp 107ndash110 2000

[135] J A Buege and S D Aust ldquoMicrosomal lipid peroxidationrdquoMethods in Enzymology vol 52 pp 302ndash310 1978

[136] R Jayabalan P Subathradevi S Marimuthu M Sathishkumarand K Swaminathan ldquoChanges in free-radical scavengingability of kombucha tea during fermentationrdquo Food Chemistryvol 109 no 1 pp 227ndash234 2008

[137] M Nishikimi N A Rao and K Yagi ldquoThe occurrence of super-oxide anion in the reaction of reduced phenazine methosulfateand molecular oxygenrdquo Biochemical and Biophysical ResearchCommunications vol 46 no 2 pp 849ndash854 1972

[138] S Ercisli M Akbulut O Ozdemir M Sengul and EOrhan ldquoPhenolic and antioxidant diversity among persimmon(Diospyrus kaki L) genotypes in Turkeyrdquo International Journalof Food Sciences and Nutrition vol 59 no 6 pp 477ndash482 2008

[139] K U Yilmaz S Ercisli Y Zengin M Sengul and E Y KafkasldquoPreliminary characterisation of cornelian cherry (CornusmasL) genotypes for their physico-chemical propertiesrdquo FoodChemistry vol 114 no 2 pp 408ndash412 2009

[140] T Noro Y Oda T Miyase A Ueno and S FukushimaldquoInhibitors of xanthine oxidase from the flowers and buds ofDaphne genkwardquoChemical and Pharmaceutical Bulletin vol 31no 11 pp 3984ndash3987 1983

[141] J M McCord and I Fridovich ldquoSuperoxide dismutase Anenzymic function for erythrocupreinrdquoThe Journal of BiologicalChemistry vol 244 no 22 pp 6049ndash6055 1969

[142] H Aebi ldquoCatalase in vitrordquoMethods in Enzymology vol 105 pp121ndash126 1984

[143] T Guo L Wei J Sun C-L Hou and L Fan ldquoAntioxidantactivities of extract and fractions from Tuber indicum Cookeamp Masseerdquo Food Chemistry vol 127 no 4 pp 1634ndash1640 2011

[144] C Soler-Rivas J C Espın and H J Wichers ldquoAn easy andfast test to compare total free radical scavenger capacity of


foodstuffsrdquo Phytochemical Analysis vol 11 no 5 pp 330ndash3382000

[145] R L Prior G Cao A Martin et al ldquoAntioxidant capacity asinfluenced by total phenolic and anthocyanin content maturityand variety of vaccinium speciesrdquo Journal of Agricultural andFood Chemistry vol 46 no 7 pp 2686ndash2693 1998

[146] G Cao H M Alessio and R G Cutler ldquoOxygen-radicalabsorbance capacity assay for antioxidantsrdquo Free Radical Biologyand Medicine vol 14 no 3 pp 303ndash311 1993

[147] B Ou D Huang M Hampsch-Woodill J A Flanagan and EK Deemer ldquoAnalysis of antioxidant activities of common veg-etables employing oxygen radical absorbance capacity (ORAC)and ferric reducing antioxidant power (FRAP) assays a com-parative studyrdquo Journal of Agricultural and Food Chemistry vol50 no 11 pp 3122ndash3128 2002

[148] B Ou M Hampsch-Woodill J Flanagan E K Deemer R LPrior and D Huang ldquoNovel fluorometric assay for hydroxylradical prevention capacity using fluorescein as the proberdquoJournal of Agricultural and Food Chemistry vol 50 no 10 pp2772ndash2777 2002

[149] A Ghiselli M Serafini G Maiani E Azzini and A Fer-ro-Luzzi ldquoA fluorescence-based method for measuring totalplasma antioxidant capabilityrdquo Free Radical Biology andMedicine vol 18 no 1 pp 29ndash36 1995

[150] D D M Wayner G W Burton K U Ingold and SLocke ldquoQuantitative measurement of the total peroxyl radical-trapping antioxidant capability of human blood plasma bycontrolled peroxidation The important contribution made byplasma proteinsrdquo FEBS Letters vol 187 no 1 pp 33ndash37 1985

[151] S R J Maxwell O Wiklund and G Bondjers ldquoMeasurementof antioxidant activity in lipoproteins using enhanced chemilu-minescencerdquo Atherosclerosis vol 111 no 1 pp 79ndash89 1994

[152] A W Bott ldquoPractical problems in voltammetry 2 Electrodecapacitancerdquo Current Separations vol 12 pp 10ndash13 1993

[153] S Chevion M A Roberts and M Chevion ldquoThe use of cyclicvoltammetry for the evaluation of antioxidant capacityrdquo FreeRadical Biology and Medicine vol 28 no 6 pp 860ndash870 2000

[154] M Seruga I Novak and L Jakobek ldquoDetermination ofpolyphenols content and antioxidant activity of some red winesby differential pulse voltammetry HPLC and spectrophotomet-ricmethodsrdquo FoodChemistry vol 124 no 3 pp 1208ndash1216 2011

[155] S P Kounaves ldquoVoltammetric techniquesrdquo in Handbook ofInstrumental Techniques for Analytical Chemistry F A SettleEd chapter 37 Prentice Hall Upper Saddle River NJ USA1997

[156] J Sochor J Dobes O Krystofova et al ldquoElectrochemistry as atool for studying antioxidant propertiesrdquo International Journalof Electrochemical Science vol 8 no 6 pp 8464ndash8489 2013

[157] P Jakubec M Bancirova V Halouzka et al ldquoElectrochemicalsensing of total antioxidant capacity and polyphenol content inwine samples using amperometry online-coupled with micro-dialysisrdquo Journal of Agricultural and Food Chemistry vol 60 no32 pp 7836ndash7843 2012

[158] S Milardovic D Ivekovic V Rumenjak and B S GrabaricldquoUse of DPPH∙DPPH redox couple for biamperometric deter-mination of antioxidant activityrdquo Electroanalysis vol 17 pp1847ndash1853 2005

[159] S Milardovic I Kerekovic R Derrico and V Rumenjak ldquoAnovel method for flow injection analysis of total antioxidantcapacity using enzymatically produced ABTS∙+ and biamper-ometric detector containing interdigitated electroderdquo Talantavol 71 no 1 pp 213ndash220 2007

[160] S Milardovic I Kerekovic and V Rumenjak ldquoA flow injectionbiamperometric method for determination of total antioxidantcapacity of alcoholic beverages using bienzymatically producedABTS∙+rdquo Food Chemistry vol 105 pp 1688ndash1694 2007

[161] L K Shpigun M A Arharova K Z Brainina and A VIvanova ldquoFlow injection potentiometric determination of totalantioxidant activity of plant extractsrdquo Analytica Chimica Actavol 573-574 pp 419ndash426 2006

[162] N Gougoulias ldquoEvaluation of antioxidant activity and polyphe-nol content of leaves from some fruit speciesrdquo OxidationCommunications vol 38 pp 35ndash45 2015

[163] V Katalinic S S Mozina I Generalic D Skroza I Ljubenkovand A Klancnik ldquoPhenolic profile antioxidant capacity andantimicrobial activity of leaf extracts from six vitis vinifera LVarietiesrdquo International Journal of Food Properties vol 16 no 1pp 45ndash60 2013

[164] N G Sahib A A Hamid N Saari F Abas M S P Dek andM Rahim ldquoAnti-pancreatic lipase and antioxidant activity ofselected tropical herbsrdquo International Journal of Food Propertiesvol 15 no 3 pp 569ndash578 2012

[165] S Karoune H Falleh M S A Kechebar et al ldquoEvaluationof antioxidant activities of the edible and medicinal Acaciaalbida organs related to phenolic compoundsrdquo Natural ProductResearch vol 29 no 5 pp 452ndash454 2015

[166] H ZhangW Xi Y Yang et al ldquoAn on-line HPLC-FRSD systemfor rapid evaluation of the total antioxidant capacity of Citrusfruitsrdquo Food Chemistry vol 172 pp 622ndash629 2015

[167] L Vicas A Teusdea S Vicas et al ldquoAssessment of antioxidantcapacity of some extracts for further use in therapyrdquo Farmaciavol 63 no 2 pp 267ndash274 2015

[168] M Makni A Haddar W Kriaa and N Zeghal ldquoAntioxidantfree radical scavenging and antimicrobial activities ofAjuga ivaleaf extractsrdquo International Journal of FoodProperties vol 16 no4 pp 756ndash765 2013

[169] M Pukalskiene P R Venskutonis and A Pukalskas ldquoPhyto-chemical composition and antioxidant properties of Filipendulavulgaris as a source of healthy functional ingredientsrdquo Journalof Functional Foods vol 15 pp 233ndash242 2015

[170] A Peksel S Imamoglu N A Kiymaz and N Orhan ldquoAntiox-idant and radical scavenging activities of Asphodelus aestivusBrot extractsrdquo International Journal of Food Properties vol 16no 6 pp 1339ndash1350 2013

[171] M Zahoor M Ahmed S Naz and M Ayaz ldquoCytotoxicantibacterial and antioxidant activities of extracts of the bark ofMelia azedarach (China Berry)rdquo Natural Product Research vol29 no 12 pp 1170ndash1172 2015

[172] H-J Ko L-H Ang and L-T Ng ldquoAntioxidant activitiesand polyphenolic constituents of bitter bean Parkia speciosardquoInternational Journal of Food Properties vol 17 no 9 pp 1977ndash1986 2014

[173] I Ky and P Teissedre ldquoCharacterisation of mediterraneangrape pomace seed and skin extracts polyphenolic content andantioxidant activityrdquo Molecules vol 20 no 2 pp 2190ndash22072015

[174] S Oueslati A Ellili J Legault et al ldquoPhenolic content antiox-idant and anti-inflammatory activities of Tunisian Diplotaxissimplex (Brassicaceae)rdquo Natural Product Research vol 29 no12 pp 1189ndash1191 2015

[175] T M Djordjevic S S Siler-Marinkovic and S I Dimitrijevic-Brankovic ldquoAntioxidant activity and total phenolic contentin some cereals and legumesrdquo International Journal of FoodProperties vol 14 no 1 pp 175ndash184 2011


[176] M C A da Silva and S R Paiva ldquoAntioxidant activity andflavonoid content of Clusia fluminensis PlanchampTrianardquoAnaisda Academia Brasileira de Ciencias vol 84 no 3 pp 609ndash6162012

[177] L Yu J-X Ren H-M Nan and B-F Liu ldquoIdentification ofantibacterial and antioxidant constituents of the essential oilsof Cynanchum chinense and Ligustrum compactumrdquo NaturalProduct Research vol 29 no 18 pp 1779ndash1782 2015

[178] A Monroy-Vasquez A Totosaus L R G Gonzales K A de laFuente Salazar and I Garcia-Martinez ldquoAntioxidantes I Chileancho (Caspicum annum L grossum sendt) y romero (Ros-marinus officinalis L) como fuentes naturales de antioxidantesrdquoCiencia y Tecnologia vol 6 pp 112ndash116 2007

[179] I Cesari M Hoerle C Simoes-Pires et al ldquoAnti-inflammatoryantimicrobial and antioxidant activities of Diospyros bipin-densis (Gurke) extracts and its main constituentsrdquo Journal ofEthnopharmacology vol 146 no 1 pp 264ndash270 2013

[180] B Mahdi-Pour S L Jothy L Y Latha Y Chen and S Sasid-haran ldquoAntioxidant activity of methanol extracts of differentparts of Lantana camarardquo Asian Pacific Journal of TropicalBiomedicine vol 2 no 12 pp 960ndash965 2012

[181] D Amendola D M De Faveri and G Spigno ldquoGrape marcphenolics extraction kinetics quality and stability of extractsrdquoJournal of Food Engineering vol 97 no 3 pp 384ndash392 2010

[182] D Wozniak A Drys and A Matkowski ldquoAntiradical andantioxidant activity of flavones from Scutellariae baicalensisradixrdquo Natural Product Research vol 29 no 16 pp 1567ndash15702015

[183] S Ouchemoukh S Hachoud H Boudraham A Mokraniand H Louaileche ldquoAntioxidant activities of some dried fruitsconsumed in Algeriardquo LWTmdashFood Science and Technology vol49 no 2 pp 329ndash332 2012

[184] S C Gouveia-Figueira and P C Castilho ldquoPhenolic screeningby HPLC-DAD-ESIMSn and antioxidant capacity of leavesflowers and berries of Rubus grandifolius Lowerdquo IndustrialCrops and Products vol 73 pp 28ndash40 2015

[185] L Adnan A Osman and A A Hamid ldquoAntioxidant activityof different extracts of red pitaya (Hylocereus polyrhizus) seedrdquoInternational Journal of Food Properties vol 14 no 6 pp 1171ndash1181 2011

[186] E Celep A Aydın and E Yesilada ldquoA comparative studyon the in vitro antioxidant potentials of three edible fruitscornelian cherry Japanese persimmon and cherry laurelrdquo Foodand Chemical Toxicology vol 50 no 9 pp 3329ndash3335 2012

[187] A Bucchini D Ricci F Messina M C Marcotullio M Curiniand L Giamperi ldquoAntioxidant and antifungal activity of differ-ent extracts obtained from aerial parts of Inula crithmoides LrdquoNatural Product Research vol 29 no 12 pp 1173ndash1176 2015

[188] B Abdennacer M Karim M Yassine R Nesrine D Mounaand B Mohamed ldquoDetermination of phytochemicals andantioxidant activity of methanol extracts obtained from thefruit and leaves of Tunisian Lycium intricatum Boissrdquo FoodChemistry vol 174 pp 577ndash584 2015

[189] A Kumari and R A Sharma ldquoEstimation of total phenolicflavonoidal content and evaluation of antioxidant activity ofmethanolic extract of Millingtonia hortensis Linnrdquo WorldJournal of Pharmacy and Pharmaceutical Sciences vol 3 pp1646ndash1655 2014

[190] BMhamdi F Abbassi and C Abdelly ldquoChemical compositionantioxidant and antimicrobial activities of the edible medici-nal Ononis natrix growing wild in Tunisiardquo Natural ProductResearch vol 29 no 12 pp 1157ndash1160 2015

[191] M S Mokbel and T Suganuma ldquoAntioxidant and antimicrobialactivities of the methanol extracts from pummelo (Citrusgrandis Osbeck) fruit albedo tissues rdquo European Food Researchand Technology vol 224 no 1 pp 39ndash47 2006

[192] GHasbal T Yilmaz-Ozden andA Can ldquoAntioxidant and anti-acetylcholinesterase activities of Sorbus torminalis (L) Crantz(wild service tree) fruitsrdquo Journal of Food and Drug Analysisvol 23 no 1 pp 57ndash62 2015

[193] R Singh and N Kumari ldquoComparative determination ofphytochemicals and antioxidant activity from leaf and fruitof Sapindus mukorrossi Gaertnmdasha valuable medicinal treerdquoIndustrial Crops and Products vol 73 pp 1ndash8 2015

[194] D Samec K Durgo J Gruz et al ldquoGenetic and phytochemicalvariability of six teucrium arduini L populations and theirantioxidantprooxidant behaviour examined by biochemicalmacromolecule- and cell-based approachesrdquo Food Chemistryvol 186 pp 298ndash305 2015

[195] Q V Vuong N Zammit B R Munro S Murchie M CBowyer and C J Scarlett ldquoEffect of drying conditions onphysicochemical and antioxidant properties of Vitex agnus-castus leavesrdquo Journal of Food Processing and Preservation vol39 no 6 pp 2562ndash2571 2015

[196] N Arora and S Pandey-Rai ldquoGC-MS analysis of the essentialoil of Celastrus paniculatus Willd seeds and antioxidant anti-inflammatory study of its various solvent extractsrdquo IndustrialCrops and Products vol 61 pp 345ndash351 2014

[197] V R De Souza P A P Pereira F Queiroz S V Borgesand J De Deus Souza Carneiro ldquoDetermination of bioactivecompounds antioxidant activity and chemical composition ofCerrado Brazilian fruitsrdquo Food Chemistry vol 134 no 1 pp381ndash386 2012

[198] I Sedej M Sakac A Mandic A Misan V Tumbas andJ Canadanovic-Brunet ldquoBuckwheat (Fagopyrum esculentumMoench) grain and fractions antioxidant compounds andactivitiesrdquo Journal of Food Science vol 77 no 9 pp C954ndashC9592012

[199] C Summa F C Raposo J McCourt et al ldquoEffect of roasting onthe radical scavenging activity of cocoa beansrdquo European FoodResearch and Technology vol 222 no 3-4 pp 368ndash375 2006

[200] A Szydłowska-Czerniak A Tułodziecka and E Szłyk ldquoA silvernanoparticle-based method for determination of antioxidantcapacity of rapeseed and its productsrdquo Analyst vol 137 no 16pp 3750ndash3759 2012

[201] S Chevion M Chevion P B Chock and G R BeecherldquoAntioxidant capacity of edible plants extraction protocol anddirect evaluation by cyclic voltammetryrdquo Journal of MedicinalFood vol 2 no 1 pp 1ndash10 1999

[202] M S Cosio S Buratti S Mannino and S Benedetti ldquoUse of anelectrochemical method to evaluate the antioxidant activity ofherb extracts from the Labiatae familyrdquo Food Chemistry vol 97no 4 pp 725ndash731 2006

[203] D R Babu and G N Rao ldquoAntioxidant properties and elec-trochemical behavior of cultivated commercial Indian ediblemushroomsrdquo Journal of Food Science and Technology vol 50no 2 pp 301ndash308 2013

[204] L Campanella E Martini and M Tomassetti ldquoAntioxidantcapacity of the algae using a biosensor methodrdquo Talanta vol66 no 4 pp 902ndash911 2005

[205] D Zielinska W Wiczkowski M K Piskula and M K PiskułaldquoEvaluation of photochemiluminiscent spectrophotometricand cyclic voltammetry methods for the measurement of the


antioxidant capacity the case of roots separated from buck-wheat sproutsrdquo Polish Journal of Food and Nutrition Sciencesvol 58 pp 65ndash72 2008

[206] A Pekal P Drozdz M Biesaga and K Pyrzynska ldquoPolypheno-lic content and comparative antioxidant capacity of flavouredblack teasrdquo International Journal of Food Sciences and Nutritionvol 63 no 6 pp 742ndash748 2012

[207] Y-T Tung J-H Wu Y-H Kuo and S-T Chang ldquoAntioxidantactivities of natural phenolic compounds from Acacia confusabarkrdquo Bioresource Technology vol 98 no 5 pp 1120ndash1123 2007

[208] S Gorjanovic D Komes F T Pastor et al ldquoAntioxidant capacityof teas and herbal infusions polarographic assessmentrdquo Journalof Agricultural and Food Chemistry vol 60 no 38 pp 9573ndash9580 2012

[209] M L Rodrıguez-Mendez C Apetrei and J A de Saja ldquoEvalu-ation of the polyphenolic content of extra virgin olive oils usingan array of voltammetric sensorsrdquo Electrochimica Acta vol 53no 20 pp 5867ndash5872 2008

[210] FMA Lino L Z de Sa IM S Torres et al ldquoVoltammetric andspectrometric determination of antioxidant capacity of selectedwinesrdquo Electrochimica Acta vol 128 pp 25ndash31 2014

[211] E M Ervin and J K Kariuki ldquoEffect of extraction methodon antioxidant determination in produce by differential pulsevoltammetryrdquo International Journal of Electrochemical Sciencevol 9 no 11 pp 6235ndash6245 2014

[212] V Katalinic M Milos T Kulisic and M Jukic ldquoScreening of70 medicinal plant extracts for antioxidant capacity and totalphenolsrdquo Food Chemistry vol 94 no 4 pp 550ndash557 2006

[213] A M Fernandes de Oliveira L S Pinheiro C K S Pereiraet al ldquoTotal phenolic content and antioxidant activity of somemalvaceae family speciesrdquo Antioxidants vol 1 no 1 pp 33ndash432012

[214] S Gorinstein O J M Vargas N O Jaramillo et al ldquoThe totalpolyphenols and the antioxidant potentials of some selectedcereals and pseudocerealsrdquo European Food Research and Tech-nology vol 225 no 3-4 pp 321ndash328 2007

[215] N Pellegrini M Serafini B Colombi et al ldquoTotal antioxidantcapacity of plant foods beverages and oils consumed in Italyassessed by three different in vitro assaysrdquo Journal of Nutritionvol 133 no 9 pp 2812ndash2819 2003

[216] M S Fernandez-Pachon D Villano M C Garcıa-Parrilla andAM Troncoso ldquoAntioxidant activity of wines and relationwiththeir polyphenolic compositionrdquo Analytica Chimica Acta vol513 no 1 pp 113ndash118 2004

[217] L Pistelli C Noccioli M Martera et al ldquoAntioxidant flavonolglycosides from Dorycnium hirsutumrdquo Chemistry of NaturalCompounds vol 42 no 3 pp 281ndash284 2006

[218] V L Singleton and J A Rossi Jr ldquoColorimetry of total phenolicswith phosphomolibdic-phosphotungtic acid reagentsrdquo Ameri-can Journal of Enology and Viticulture vol 16 pp 144ndash158 1965

[219] C N T Frizon G A Oliveira C A Perussello et al ldquoDeter-mination of total phenolic compounds in yerba mate (Ilexparaguariensis) combining near infrared spectroscopy (NIR)and multivariate analysisrdquo LWTmdashFood Science and Technologyvol 60 no 2 pp 795ndash801 2015

[220] S R Georgetti R Casagrande V M Di Mambro A E CS Azzolini and M J V Fonseca ldquoEvaluation of the antioxi-dant activity of different flavonoids by the chemiluminescencemethodrdquo AAPS PharmSciTech vol 5 no 2 pp 111ndash115 2003

[221] L Campanella E Martini G Rita andM Tomassetti ldquoAntiox-idant capacity of dry vegetal extracts checked by voltammetric

methodrdquo Journal of Food Agriculture and Environment vol 4no 1 pp 135ndash144 2006

[222] P A Kilmartin H L Zou and A L Waterhouse ldquoA cyclicvoltammetry method suitable for characterizing antioxidantproperties of wine and wine phenolicsrdquo Journal of Agriculturaland Food Chemistry vol 49 no 4 pp 1957ndash1965 2001

[223] X Ceto J M Gutierrez M Gutierrez et al ldquoDeterminationof total polyphenol index in wines employing a voltammetricelectronic tonguerdquo Analytica Chimica Acta vol 732 pp 172ndash179 2012

[224] O Tokusoglu S Kocak and S Aycan ldquoThe contents of sesamoland related lignans in sesame tahina and halva as determinedby a newly developed polarographic and stripping voltametricanalysisrdquo Grasas y Aceites vol 60 no 2 pp 119ndash124 2009

[225] E I Korotkova O A Voronova and E V Dorozhkob ldquoStudy ofantioxidant properties of flavonoids by voltammetryrdquo Journal ofSolid State Electrochemistry vol 16 no 7 pp 2435ndash2440 2012

[226] M F Barroso N de-los-Santos-Alvarez M J Lobo-Castanonet al ldquoDNA-based biosensor for the electrocatalytic determi-nation of antioxidant capacity in beveragesrdquo Biosensors andBioelectronics vol 26 no 5 pp 2396ndash2401 2011

[227] N de-los-Santos-Alvarez P de-los-Santos-Alvarez M J Lobo-Castanon R Lopez A J Miranda-Ordieres and P Tunon-Blanco ldquoElectrochemical oxidation of guanosine and adeno-sine two convergent pathwaysrdquo Electrochemistry Communica-tions vol 9 no 8 pp 1862ndash1866 2007

[228] J Gine Bordonaba and L A Terry ldquoElectrochemical behaviourof polyphenol rich fruit juices using disposable screen-printedcarbon electrodes towards a rapid sensor for antioxidantcapacity and individual antioxidantsrdquo Talanta vol 90 pp 38ndash45 2012

[229] F J N Maia C D S Clemente T M B F Oliveira etal ldquoElectrochemical and computational studies of phenolicantioxidants from cashew nut shell liquidrdquo Electrochimica Actavol 79 pp 67ndash73 2012

[230] T Wu Y Guan and J Ye ldquoDetermination of flavonoids andascorbic acid in grapefruit peel and juice by capillary elec-trophoresis with electrochemical detectionrdquo Food Chemistryvol 100 no 4 pp 1573ndash1579 2007

[231] S Chan-Eam S Teerasong K Damwan D Nacapricha and RChaisuksant ldquoSequential injection analysis with electrochemi-cal detection as a tool for economic and rapid evaluation of totalantioxidant capacityrdquo Talanta vol 84 no 5 pp 1350ndash1354 2011

[232] P Ibarra-Escutia J J Gomez C Calas-Blanchard J L Martyand M T Ramırez-Silva ldquoAmperometric biosensor based on ahigh resolution photopolymer deposited onto a screen-printedelectrode for phenolic compoundsmonitoring in tea infusionsrdquoTalanta vol 81 no 4-5 pp 1636ndash1642 2010

[233] I M Apetrei G Bahrim and M L Rodriguez-Mendez ldquoElec-trochemical study of poliphenols with amperometric tyrosinasebased biosensorsrdquoRomanian Biotechnological Letters vol 17 pp7684ndash7693 2012

[234] L Campanella A Bonanni G Favero and M TomassettildquoDetermination of antioxidant properties of aromatic herbsolives and fresh fruit using an enzymatic sensorrdquoAnalytical andBioanalytical Chemistry vol 375 no 8 pp 1011ndash1016 2003

[235] R de Queiroz and L A Ferreira ldquoElectrochemical determina-tion of the antioxidant capacity of Brazilianwoods as alternativematerials for the aging of cachacardquo Brazilian Journal of FoodTechnology pp 27ndash33 VII BMCFB 2009

[236] R D Q Ferreira and L A Avaca ldquoElectrochemical determina-tion of the antioxidant capacity the ceric reducingantioxidant


capacity (CRAC) assayrdquo Electroanalysis vol 20 no 12 pp 1323ndash1329 2008

[237] M Cheregi and A F Danet ldquoFlow injection determination ofL-ascorbic acid in natural juice with biamperometric detectionrdquoAnalytical Letters vol 30 no 14 pp 2625ndash2640 1997

[238] I F Abdullin E N Turova G K Ziyatdinova and G KBudnikov ldquoPotentiometric determination of ascorbic acidestimation of its contribution to the total antioxidant capacityof plant materialsrdquo Journal of Analytical Chemistry vol 57 pp353ndash355 2002 (Translated from Zhurnal Analiticheskoi Khimiivol 57 no 4 pp 418ndash421 2002)

[239] H Metrouh-Amir C M M Duarte and F Maiza ldquoSolventeffect on total phenolic contents antioxidant and antibacterialactivities of Matricaria pubescensrdquo Industrial Crops and Prod-ucts vol 67 pp 249ndash256 2015

[240] S D Torti M D Dearing and T A Kursar ldquoExtractionof phenolic compounds from fresh leaves a comparison ofmethodsrdquo Journal of Chemical Ecology vol 21 no 2 pp 117ndash1251995

[241] L Tomsone Z Kruma and R Galoburda ldquoComparison of dif-ferent solvents and extraction methods for isolation of phenoliccompounds from horseradish roots (Armoracia rusticana)rdquoInternational Journal of Biological Biomolecular AgriculturalFood and Biotechnological Engineering vol 6 pp 903ndash908 2012

[242] A Karimi B Min C Brownmiller and S-O Lee ldquoEffects ofextraction techniques on total phenolic content and antioxidantcapacities of two oregano leavesrdquo Journal of Food Research vol4 no 1 pp 112ndash123 2015

[243] M N Hasmida A R Nur Syukriah M S Liza and C YMohd Azizi ldquoEffect of different extraction techniques on totalphenolic content and antioxidant activity of quercus infectoriagallsrdquo International Food Research Journal vol 21 no 3 pp1039ndash1043 2014

[244] P Arulpriya and P Lalitha ldquoEvaluation of different extractionmethods for optimization of extraction of aerial roots ofRhaphidophora aurea entwined over two diverse host treesrdquoInternational Journal of ChemTech Research vol 5 no 5 pp2173ndash2176 2013

[245] A Frum ldquoResveratrol extraction and analysis methods fromdifferent plant partsrdquo Journal of Agroalimentary Processes andTechnologies vol 21 pp 95ndash101 2015

[246] M E Embuscado ldquoSpices and herbs natural sources ofantioxidantsmdasha mini reviewrdquo Journal of Functional Foods vol18 pp 811ndash819 2015

[247] S K Chang CAlasalvar and F Shahidi ldquoReviewof dried fruitsphytochemicals antioxidant efficacies and health benefitsrdquoJournal of Functional Foods vol 21 pp 113ndash132 2016

[248] A Karadag B Ozcelik and S Saner ldquoReview of methods todetermine antioxidant capacitiesrdquo FoodAnalyticalMethods vol2 no 1 pp 41ndash60 2009

[249] E Niki and N Noguchi ldquoEvaluation of antioxidant capacityWhat capacity is being measured by which methodrdquo IUBMBLife vol 50 no 4-5 pp 323ndash329 2000

[250] E N Frankel and A S Meyer ldquoThe problems of using one-dimensional methods to evaluate multifunctional food andbiological antioxidantsrdquo Journal of the Science of Food andAgriculture vol 80 no 13 pp 1925ndash1941 2000

[251] J M C Gutteridge ldquoLipid peroxidation and antioxidants asbiomarkers of tissue damagerdquo Clinical Chemistry vol 41 no 12pp 1819ndash1828 1995

[252] V Sartor P T Henderson and G B Schuster ldquoRadical cationtransport and reaction in RNADNA hybrid duplexes effect ofglobal structure on reactivityrdquo Journal of the American ChemicalSociety vol 121 no 48 pp 11027ndash11033 1999

[253] X Dai Q Huang B Zhou Z Gong Z Liu and S Shi ldquoPrepar-ative isolation and purification of sevenmain antioxidants fromEucommia ulmoides Oliv (Du-zhong) leaves using HSCCCguided by DPPH-HPLC experimentrdquo Food Chemistry vol 139no 1ndash4 pp 563ndash570 2013

[254] L-Q Sun X-P Ding J Qi et al ldquoAntioxidant anthocyaninsscreening through spectrum-effect relationships and DPPH-HPLC-DAD analysis on nine cultivars of introduced rabbiteyeblueberry inChinardquoFoodChemistry vol 132 no 2 pp 759ndash7652012

[255] J Liu L Jia J Kan and C-H Jin ldquoIn vitro and in vivo antiox-idant activity of ethanolic extract of white button mushroom(Agaricus bisporus)rdquo Food and Chemical Toxicology vol 51 no1 pp 310ndash316 2013

[256] E Niki ldquoAssessment of antioxidant capacity in vitro and in vivordquoFree Radical Biology and Medicine vol 49 no 4 pp 503ndash5152010

[257] M Oroian and I Escriche ldquoAntioxidants characterizationnatural sources extraction and analysisrdquo Food Research Inter-national vol 74 pp 10ndash36 2015

[258] D Krishnaiah R Sarbatly and R Nithyanandam ldquoA review ofthe antioxidant potential of medicinal plant speciesrdquo Food andBioproducts Processing vol 89 no 3 pp 217ndash233 2011

[259] httpwwwarsusdagovservicesdocshtmdocid=15866[260] K Thaipong U Boonprakob K Crosby L Cisneros-Zevallos

and D Hawkins Byrne ldquoComparison of ABTS DPPH FRAPandORACassays for estimating antioxidant activity fromguavafruit extractsrdquo Journal of Food Composition and Analysis vol 19no 6-7 pp 669ndash675 2006

[261] E A Ainsworth and K M Gillespie ldquoEstimation of totalphenolic content and other oxidation substrates in plant tissuesusing Folin-Ciocalteu reagentrdquo Nature Protocols vol 2 no 4pp 875ndash877 2007

[262] A B Ribeiro E G Bonafe B C Silva et al ldquoAntioxidantcapacity total phenolic content fatty acids and correlation byprincipal component analysis of exotic and native fruits fromBrazilrdquo Journal of the Brazilian Chemical Society vol 24 no 5pp 797ndash804 2013

[263] W Wangcharoen and W Morasuk ldquoAntioxidant capacity andphenolic content of holy basilrdquo Songklanakarin Journal ofScience and Technology vol 29 no 5 pp 1407ndash1415 2007

[264] M F Wang Y Shao J G Li et al ldquoAntioxidative phenolic com-pounds from Sage (Salvia officinalis)rdquo Journal of Agriculturaland Food Chemistry vol 46 pp 4869ndash4873 1998

[265] M J T J Arts G R M M Haenen H-P Voss and ABast ldquoAntioxidant capacity of reaction products limits theapplicability of the Trolox Equivalent Antioxidant Capacity(TEAC) assayrdquo Food and Chemical Toxicology vol 42 no 1 pp45ndash49 2004

[266] V G Hartwig L A Brumovsky R M Fretes and L SanchezBoado ldquoA novel procedure to measure the antioxidant capacityof yerba mate extractsrdquo Ciencia e Tecnologia de Alimentos vol32 no 1 pp 126ndash133 2012

[267] J F Arteaga M Ruiz-Montoya A Palma G Alonso-GarridoS Pintado and J M Rodrıguez-Mellad ldquoComparison of thesimple cyclic voltammetry (CV) and DPPH assays for thedetermination of antioxidant capacity of active principlesrdquoMolecules vol 17 no 5 pp 5126ndash5138 2012


[268] OMakhotkina and P A Kilmartin ldquoThe phenolic compositionof Sauvignon blanc juice profiled by cyclic voltammetryrdquoElectrochimica Acta vol 83 pp 188ndash195 2012

[269] A M Pisoschi C Cimpeanu and G Predoi ldquoElectrochemicalmethods for total antioxidant capacity and itsmain contributorsdetermination a reviewrdquoOpenChemistry vol 13 no 1 pp 824ndash856 2015

[270] A M Pisoschi ldquoBiosensors as bio-based materials in chemicalanalysis a reviewrdquo Journal of Biobased Materials and Bioenergyvol 7 no 1 pp 19ndash38 2013

[271] A M Pisoschi and G P Negulescu ldquoMethods for totalantioxidant activity determination a reviewrdquo Biochemistry ampAnalytical Biochemistry vol 1 no 1 article 106 2012

[272] A M Pisoschi M C Cheregi and A F Danet ldquoTotal antioxi-dant capacity of some commercial fruit juices electrochemicaland spectrophotometrical approachesrdquoMolecules vol 14 no 1pp 480ndash493 2009

[273] C Hengst S Werner L Muller K Frohlich and V BohmldquoDetermination of the antioxidant capacity influence of thesample concentration on the measured valuesrdquo European FoodResearch and Technology vol 230 no 2 pp 249ndash254 2009

[274] R Apak S Gorinstein V Bohm K M Schaich M Ozyurekand K Guclu ldquoMethods of measurement and evaluation of nat-ural antioxidant capacityactivity (IUPAC Technical Report)rdquoPure and Applied Chemistry vol 85 no 5 pp 957ndash998 2013

[275] O I Aruoma ldquoMethodological considerations for character-izing potential antioxidant actions of bioactive components inplant foodsrdquoMutation Research vol 523-524 pp 9ndash20 2003

[276] J Perez-Jimenez S Arranz M Tabernero et al ldquoUpdatedmethodology to determine antioxidant capacity in plant foodsoils and beverages extraction measurement and expression ofresultsrdquo Food Research International vol 41 no 3 pp 274ndash2852008

Submit your manuscripts athttpwwwhindawicom

Stem CellsInternational

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014


MEDIATORSINFLAMMATION

of


Behavioural Neurology

EndocrinologyInternational Journal of



Disease Markers


BioMed Research International

OncologyJournal of



Oxidative Medicine and Cellular Longevity


PPAR Research

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Immunology ResearchHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

ObesityJournal of



Computational and Mathematical Methods in Medicine

OphthalmologyJournal of


Diabetes ResearchJournal of



Research and TreatmentAIDS


Gastroenterology Research and Practice


Parkinsonrsquos Disease

Evidence-Based Complementary and Alternative Medicine

Volume 2014Hindawi Publishing Corporationhttpwwwhindawicom


and may undergo tautomerization yielding enediols thatare easily subject to autooxidation This step is initiatedand propagated by superoxide radical 120572- and 120573-dicarbonylsmay also result during this glycolaldehyde autooxidation [11]Peroxidation of lipids means primarily the attack to the fattyacidrsquos chain by a radical which abstracts a hydrogen atomfrom a methylene group with polyunsaturated fatty acidsbeing the most susceptible to undergo this process OH∙ asone of the most active radical species and HO2

∙ attack lipidsubstrates (L-H) yielding the corresponding lipid radicals L∙The attack on polyunsaturated fatty acids by singlet oxygencan yield lipid peroxides [12 13]

In recent studies it has been repeatedly asserted thatoxidative stress not only is not limited to free radical-induceddamage on biomolecules but also involves perturbation ofcellular redox status which has been described as ldquoa disrup-tion in redox signaling and controlrdquo hence the antioxidantsystem implies more than mere free radical capture [14ndash17]

Oxidative stress-induced pathology includes cancer [1819] cardiovascular disease [20] neural disorders [21]Alzheimerrsquos disease [22] mild cognitive impairment [23]Parkinsonrsquos disease [24] alcohol induced liver disease [25]ulcerative colitis [26] atherosclerosis [27] and aging [28]

The antioxidant action mechanism cannot be under-stood without describing the model lipid peroxidation incell membranes or foodstuffs a radical mechanism thatthese biomolecules undergowith initiation propagation andchain termination stages which is promoted by heat lightand ionizing radiation or by metal ions or metalloproteins[29ndash31]

Initiation

LH + R∙ 997888rarr L∙ + RH (1)

LH is the lipid substrate R∙ is the initiating oxidizing radicaland L∙ is the allyl radical endowed with high reactivity

Propagation

L∙ +O2 997888rarr LOO∙

LOO∙ + LH 997888rarr L∙ + LOOH(2)

So during this step the lipid peroxyl radicals LOO∙ act aschain carriers further oxidizing the lipid substrate and gen-erating lipid hydroperoxides (LOOH) which can decomposeinto alcohols aldehydes alkyl formates ketones hydrocar-bons and radicals such as lipid alkoxyl radical LO∙ [3 32]

Branching

LOOH 997888rarr LO∙ +HO∙

2LOOH 997888rarr LOO∙ + LO∙ +H2O(3)

The decay of lipid hydroperoxides often takes place in thepresence of transition metal ions generating lipid peroxyland lipid alkoxyl radicals

LOOH +M119899+ +H+ 997888rarr LO∙ +M(119899+1)+ +H2O

LOOH +M(119899+1)+ +OHminus 997888rarr LOO∙ +M119899+ +H2O(4)

Termination implies the combination of radicals to formnonradical chemical species

LO∙ + LO∙ 997888rarr nonradical products

LOO∙ + LOO∙ 997888rarr nonradical products

LO∙ + LOO∙ 997888rarr nonradical products

(5)

Antioxidants can act as chain breakers scavenging chaininitiating radicals like hydroxyl alkoxyl or peroxyl quench-ing singlet oxygen decomposing hydroperoxides and chelat-ing prooxidative metal ions [13 33] Epidemiological studiesconfirm that the incidence of oxidative stress-related condi-tions is lowered by the consumption of fruits and vegetablesrich in compounds possessing high antioxidant activity[18 34ndash37] Foods containing antioxidants and antioxidantnutrients play an important role in prevention

Chain breaking antioxidants able to scavenge radicalspecies are called primary antioxidants Secondary antioxi-dants are singlet oxygen quenchers peroxide decomposersthat yield nonradical species oxidative enzyme (eg lipoxy-genase) inhibitors UV radiation absorbers or compoundsthat act by metal chelating [38ndash40]

Natural antioxidants constitute the essential part in thecellrsquos defense mechanisms and they can be endogenous orexogenous

Endogenous antioxidants can be nonenzymatic such asglutathione alpha-lipoic acid coenzyme Q ferritin uricacid bilirubin metallothionein l-carnitine melatonin albu-min and antioxidant enzyme cofactors or enzymatic suchas superoxide dismutase catalase glutathione peroxidasesthioredoxins and peroxiredoxins Peroxiredoxins regulatecytokine-induced peroxide levels and mediate cell signaltransduction [41]

Enzymatic antioxidants at their turn are grouped withinthe primary and secondary defence systems The primarydefence is formed by three crucial enzymes capable ofpreventing the occurrence or neutralizing free radicals glu-tathione peroxidase which donates two electrons that reduceperoxides catalase that decomposes hydrogen peroxide intowater and molecular oxygen and superoxide dismutase thatturns superoxide anions into hydrogen peroxide [13 41] Thesecondary enzymatic defense comprises glutathione reduc-tase and glucose-6-phosphate dehydrogenase Glutathionereductase turns glutathione into its reduced form thus recy-cling it Glucose-6-phosphate reforms reductiveNADPH [4243] Although these two enzymes do not directly neutralizefree radicals they promote the endogenous antioxidantsrsquoactivity [13] It has been assessed that enzymatic antioxidantsact by decomposing free radicals and in this case damagingoxidative species are converted into hydrogen peroxide andwater while nonenzymatic antioxidants are mainly chainbreakers For instance it has been reported that tocopheroldisrupts a radical oxidation chain after five reactions [44]

Apart from the endogenous enzymatic and nonenzy-matic antioxidants previously discussed there are also exoge-nous diet-sourced antioxidants [40 43] represented bycarotenoids tocopherols vitamin D phenolic acids flavon-oids or ascorbic acid as well as high-molecular weight








































































(d) Continued









532 nm [119]

















coefficients[91]



particle size










detection[108]




























measured at 535 nm





Table 2 Continued








activity




















the metal ion





phycoerythrin















stairstep-wise




Table 2 Continued





reference electrode


analyte[157]

Biamperometry


electrodes



Potentiometry





couple[161]












(1)





[162]















[165]



[166]











[169]



[170]







[172]





[116]


Table 3 Continued







[173]

(14)









[105]





[175]





[176]





[106]





[177]










[102]





[114]


flower)




[180]


Table 3 Continued



(25) Grape extracts



[181]



[182]

(27) Lycium species




[107]


figs and raisins)





berries)




[184]




[185]


laurel










[188]


and flower)




[189]









[192]


Table 3 Continued





[104]




[193]




[103]





[194]








[111]

(44)






[91]



Calmant [196]













[199]



[200]


Table 3 Continued







(53)






[203]

(54)



maxima




(55)








[96]



[95]






[208]




[210]

(63)
















U)

(min)

016

012

008

004

000

5 10 15 20 25 30

F1 and F2

F9

F11














PPH

sc

aven

ging


100

80

60

40

20

0

1 5 10 25 50 100





































2minus NO3minus CO3







I(120583

A)

E (mV)minus1000 200 400 600 800 1000

560

520

480

440

400

360

320

280

240

200

160

120

80

40

0

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)




















(6)



minus Fe(CN)63minus












































Competing Interests


References










































































































































































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of























































































(d) Continued









532 nm [119]

















coefficients[91]



particle size










detection[108]




























measured at 535 nm





Table 2 Continued








activity




















the metal ion





phycoerythrin















stairstep-wise




Table 2 Continued





reference electrode


analyte[157]

Biamperometry


electrodes



Potentiometry





couple[161]












(1)





[162]















[165]



[166]











[169]



[170]







[172]





[116]


Table 3 Continued







[173]

(14)









[105]





[175]





[176]





[106]





[177]










[102]





[114]


flower)




[180]


Table 3 Continued



(25) Grape extracts



[181]



[182]

(27) Lycium species




[107]


figs and raisins)





berries)




[184]




[185]


laurel










[188]


and flower)




[189]









[192]


Table 3 Continued





[104]




[193]




[103]





[194]








[111]

(44)






[91]



Calmant [196]













[199]



[200]


Table 3 Continued







(53)






[203]

(54)



maxima




(55)








[96]



[95]






[208]




[210]

(63)
















U)

(min)

016

012

008

004

000

5 10 15 20 25 30

F1 and F2

F9

F11














PPH

sc

aven

ging


100

80

60

40

20

0

1 5 10 25 50 100





































2minus NO3minus CO3







I(120583

A)

E (mV)minus1000 200 400 600 800 1000

560

520

480

440

400

360

320

280

240

200

160

120

80

40

0

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)




















(6)



minus Fe(CN)63minus












































Competing Interests


References










































































































































































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of
























coefficients[91]



particle size










detection[108]




























measured at 535 nm





Table 2 Continued








activity




















the metal ion





phycoerythrin















stairstep-wise




Table 2 Continued





reference electrode


analyte[157]

Biamperometry


electrodes



Potentiometry





couple[161]












(1)





[162]















[165]



[166]











[169]



[170]







[172]





[116]


Table 3 Continued







[173]

(14)









[105]





[175]





[176]





[106]





[177]










[102]





[114]


flower)




[180]


Table 3 Continued



(25) Grape extracts



[181]



[182]

(27) Lycium species




[107]


figs and raisins)





berries)




[184]




[185]


laurel










[188]


and flower)




[189]









[192]


Table 3 Continued





[104]




[193]




[103]





[194]








[111]

(44)






[91]



Calmant [196]













[199]



[200]


Table 3 Continued







(53)






[203]

(54)



maxima




(55)








[96]



[95]






[208]




[210]

(63)
















U)

(min)

016

012

008

004

000

5 10 15 20 25 30

F1 and F2

F9

F11














PPH

sc

aven

ging


100

80

60

40

20

0

1 5 10 25 50 100





































2minus NO3minus CO3







I(120583

A)

E (mV)minus1000 200 400 600 800 1000

560

520

480

440

400

360

320

280

240

200

160

120

80

40

0

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)




















(6)



minus Fe(CN)63minus












































Competing Interests


References










































































































































































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of

















Table 2 Continued








activity




















the metal ion





phycoerythrin















stairstep-wise




Table 2 Continued





reference electrode


analyte[157]

Biamperometry


electrodes



Potentiometry





couple[161]












(1)





[162]















[165]



[166]











[169]



[170]







[172]





[116]


Table 3 Continued







[173]

(14)









[105]





[175]





[176]





[106]





[177]










[102]





[114]


flower)




[180]


Table 3 Continued



(25) Grape extracts



[181]



[182]

(27) Lycium species




[107]


figs and raisins)





berries)




[184]




[185]


laurel










[188]


and flower)




[189]









[192]


Table 3 Continued





[104]




[193]




[103]





[194]








[111]

(44)






[91]



Calmant [196]













[199]



[200]


Table 3 Continued







(53)






[203]

(54)



maxima




(55)








[96]



[95]






[208]




[210]

(63)
















U)

(min)

016

012

008

004

000

5 10 15 20 25 30

F1 and F2

F9

F11














PPH

sc

aven

ging


100

80

60

40

20

0

1 5 10 25 50 100





































2minus NO3minus CO3







I(120583

A)

E (mV)minus1000 200 400 600 800 1000

560

520

480

440

400

360

320

280

240

200

160

120

80

40

0

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)




















(6)



minus Fe(CN)63minus












































Competing Interests


References










































































































































































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of

















Table 2 Continued





reference electrode


analyte[157]

Biamperometry


electrodes



Potentiometry





couple[161]












(1)





[162]















[165]



[166]











[169]



[170]







[172]





[116]


Table 3 Continued







[173]

(14)









[105]





[175]





[176]





[106]





[177]










[102]





[114]


flower)




[180]


Table 3 Continued



(25) Grape extracts



[181]



[182]

(27) Lycium species




[107]


figs and raisins)





berries)




[184]




[185]


laurel










[188]


and flower)




[189]









[192]


Table 3 Continued





[104]




[193]




[103]





[194]








[111]

(44)






[91]



Calmant [196]













[199]



[200]


Table 3 Continued







(53)






[203]

(54)



maxima




(55)








[96]



[95]






[208]




[210]

(63)
















U)

(min)

016

012

008

004

000

5 10 15 20 25 30

F1 and F2

F9

F11














PPH

sc

aven

ging


100

80

60

40

20

0

1 5 10 25 50 100





































2minus NO3minus CO3







I(120583

A)

E (mV)minus1000 200 400 600 800 1000

560

520

480

440

400

360

320

280

240

200

160

120

80

40

0

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)




















(6)



minus Fe(CN)63minus












































Competing Interests


References










































































































































































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of




















(1)





[162]















[165]



[166]











[169]



[170]







[172]





[116]


Table 3 Continued







[173]

(14)









[105]





[175]





[176]





[106]





[177]










[102]





[114]


flower)




[180]


Table 3 Continued



(25) Grape extracts



[181]



[182]

(27) Lycium species




[107]


figs and raisins)





berries)




[184]




[185]


laurel










[188]


and flower)




[189]









[192]


Table 3 Continued





[104]




[193]




[103]





[194]








[111]

(44)






[91]



Calmant [196]













[199]



[200]


Table 3 Continued







(53)






[203]

(54)



maxima




(55)








[96]



[95]






[208]




[210]

(63)
















U)

(min)

016

012

008

004

000

5 10 15 20 25 30

F1 and F2

F9

F11














PPH

sc

aven

ging


100

80

60

40

20

0

1 5 10 25 50 100





































2minus NO3minus CO3







I(120583

A)

E (mV)minus1000 200 400 600 800 1000

560

520

480

440

400

360

320

280

240

200

160

120

80

40

0

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)




















(6)



minus Fe(CN)63minus












































Competing Interests


References










































































































































































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of

















Table 3 Continued







[173]

(14)









[105]





[175]





[176]





[106]





[177]










[102]





[114]


flower)




[180]


Table 3 Continued



(25) Grape extracts



[181]



[182]

(27) Lycium species




[107]


figs and raisins)





berries)




[184]




[185]


laurel










[188]


and flower)




[189]









[192]


Table 3 Continued





[104]




[193]




[103]





[194]








[111]

(44)






[91]



Calmant [196]













[199]



[200]


Table 3 Continued







(53)






[203]

(54)



maxima




(55)








[96]



[95]






[208]




[210]

(63)
















U)

(min)

016

012

008

004

000

5 10 15 20 25 30

F1 and F2

F9

F11














PPH

sc

aven

ging


100

80

60

40

20

0

1 5 10 25 50 100





































2minus NO3minus CO3







I(120583

A)

E (mV)minus1000 200 400 600 800 1000

560

520

480

440

400

360

320

280

240

200

160

120

80

40

0

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)




















(6)



minus Fe(CN)63minus












































Competing Interests


References










































































































































































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of
















review article antioxidant capacity determination in plants and … · 2019. 7. 30. · review...

Documents