Download - Anti oxidants and health
Division of Biochemistry Division of Biochemistry Rajah Muthiah Medical CollegeRajah Muthiah Medical College
Annamalai UniversityAnnamalai University
Molecules that protect tissues from any free radical (molecule with unpaired electron).
Organic molecule that Minimize or prevent cellular damage
Numerous vitamins, minerals phytochemicals and certain enzymes
What are free What are free radicals?radicals?
Atom or group of atoms with an odd (unpaired) number of electron
Capable of independent existence, but are highly reactive
Initiates a chain reaction (dominoe effect)Leads to disruption of a living cellOverload of free radicals has been linked
to diseases including heart disease, liver disease and certain cancers
Formation of free Formation of free radicalradical
Metabolism of oxygen by cells form by products – free radicals
When the body breaks down certain medications
Through pollutantsOxygen molecule is a free radical
Free radical species of Free radical species of pathological importancepathological importance
Super oxide ion O2-
Hydroxyl OH-Nitric oxide NO-Ferryl ion FeO2+
Perferyl ion FeO22+
Allyl RAlkoxyl RO.Peroxyl ROO.“R” is a polymer of – CH2- -CH=group
Role of transition metal in Role of transition metal in free radical formationfree radical formation
Fenton’s ReactionFe2+ + H2O2 Fe3+ + OH + OH-
Presence of catalytic iron or copper increases the rate of formation of free radicals
Iron is carefully sequestered by a variety of proteins
Iron sequestrationIron sequestrationTransferrin and haemopexin (during
transport)
Transferrin receptors (during uptake)
Ferritin and haemosidrin (during storage)
Role of free radicals in Role of free radicals in respiratory burstrespiratory burst
Free radicals are generated by neutrophils,monocytes, eosinophils
Used to kill internalized bacteria after phagocytosis
This metabolic event is known as respiratory burst
Activation of neutrophil NADPH – dependent oxidase
Formation of superoxide O2 - hydrogen peroxide ( formed from
superoxide by SOD) Fe3+ (catalyst)
MPO (myloperoxidase)
Formation of hydroxyl Radical (OH) HOcl (hypochlorous acid)
Destruction of internalized bacteria
Chronic granulomatous disease – NADPH oxidase system is defective
Repeated severe infections
Harmful effects of free Harmful effects of free radicalsradicals• Free radicals are very unstable and highly reactive
• Forms schiff’s bases and cause damage to DNA• Lipid peroxidation - Peroxyl radicals
• In presence of Iron / copper ions
• Cytotoxic aldehydes (malondialdehydes and hydroxy noneal)
• Chemicaly modify proteins and DNA
• May produce mutations or cancer
Antioxidants – Protection Antioxidants – Protection against against
free radical damagefree radical damageAntioxidants confer protection by safely
interacting with free radicalsMode of actionChelating the transitional metal catalystsChain breaking reactionsReducing the concentration of reactive
radicalsScavenging initiating radicals
AntioxidantsAntioxidantsSuperoxide dismutaseCatalaseEnzymes Glutathione peroxidase
Natural – Vitamin E, Vitamin C, Selenium Carotenes
Non-enzymesBHTSynthetic BHA
Enzymes (Cytoprotective Enzymes (Cytoprotective enzymes)enzymes)
1. Superoxide dismutase : Zn/cu containign enzyme – cytosol Manganese – metalloprotein – mitochondria
O2- + O2
- + 2H+ H2O2 + O2
SOD
2. Catalase Peroxisome and cytosol of the cell
2H2O2 H2O + O2
catalase
3. Glutathione peroxidase Selenium containing mettaloenzyme
H2O2 + 2GSH GSSG + 2H2O Glutathione peroxidase
G.6.PD deficiency – Inability to form NADPH
causes hamolysis – hamolytic anaemia
Non-EnzymesNon-EnzymesTocopherols Functions as a chain breaking
antioxidantsAnti cancer effectFood source – Asparagus, corn oil,
hazel nuts, raw almonds, Soya beans
RDA – Man 10 mg (15 IU) Women 8 mg (12 IU)
Vit. CAnti cancer effectCombined action with tocopherolsBeneficial in smokersFood source : Amla, guava, line, lemon,
green leafy vegetablesRDA – 60 – 70 mg /dayAdditional requirement 20-40% more in
pregnancy in lactation
CarotenesScavengers of free radicals (alkoxyl and peroxyl)Beta carotenes – lowers LDL cholesterol levelsFodo soruce : Apricots, carrots, broccoli, mangoes,
peaches, peppers, pump kinsAstaxanthin – Fat soluble carotenoid – Fights
cancer and AMDRDA – Man 1000 retional equivalent (5000 IU) Women 800 retional equivalent (4000 IU)1 retional equivalent = 6 g of beta carotene
Glutathione Inactivates hydrogen peroxide and lipid peroxidesFood source: Asparagus, Avacado
SeleniumMineral forms a part of the enzyme glutathione
peroxidase that disposes free radicalsFood source : brazil nuts, sea food, organ meat
SpirulinaMicroscopic, single cell blue – green algaeFood source: Available in form of pills, flakes (sprinkle over
salad) powder
Zinc (Zn)Important component of enzymesFood source: Eggs, meat, sea food, tofu
Flavanoid Anti inflammatory plant antioxidant protects against heart
disease and cancerFood source: Blue berries, carrots, egg plants, orangesProtects ascorbic acid from being destroyed
LuteinFound in eye’s retina, carotenoids slows progression of
AMDFood source : broccoli, corn, egg yolk
PhytoestrogenIso flavones or natural plant estrogen Food source: Green tea, grapes
N-Acetylcysteine (NAC)Increases elvel fo glutathione Food source: Eggs, granola, meats
Coenzyme Q10 : Also known as ubiquinone
Lipid present in almost every plant and animal
Prevents LDL cholesterol oxidationFood Source: Broccoli, spinach, peanuts
Alpha lipoic acid : ALAPrevents oxidation of LDL, protein and DNAFood source: Beef, potato, spinach
Assessment of free Assessment of free radical damage and radical damage and antioxidant statusantioxidant status
Protein oxidationDetected by fluorescence spectroscopyLipid peroxidationDiene conjucates : early marker of lipid
peroxidation 235 – 255 mmThiobarbituric acidAbsorbance measured at 532 nm or 553
nm
Estimation of Anti-oxidant Estimation of Anti-oxidant statusstatus
Assessment of cytoprotective enzymes
a) Superoxide dismutaseb) Catalasec) Glutathione peroxidase
Diets rich in Diets rich in AntioxidantsAntioxidants
• Soya beans Green leafy vegetables• Carrots Almonds• Mangoes Amla• Pumpkin Lemon• Sea food Blue berries• Oranges Green tea• Grapes Peanuts• Sunflower oil Corn oil