pharmacology final botanical medicine
TRANSCRIPT
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Dr Leonie Curtolo
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No direct function on growth and development
= Secondary metabolites, secondary products or naturalproducts
Primary metabolites:
Chlorophyll, amino acids, nucleotides, simple carbohydrates ormembrane lipids
Recognized roles in photosynthesis, respiration, solute transport,translocation, nutrient assimilation and differentiation
Throughout plant kingdom
Secondary metabolites:
Restricted distribution in plant kingdom
Certain only found in one plant species / taxonomically related
group of species
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Funtions:
1. Defends plants against being eaten by Herbivores andinfection by pathogens
2. Plant defenses evolved to maintain reproductive fitness Evolution of metabolites lead to greater reproductive fitness than
undefended plants as long as the metabolic cost of producing them wasnot excessive
Defended plants left more descendant than undefended ones and passedtheir defensive traits on to the next generation.
Interesting that defense compounds to increase reproductive fitness bywarding off fungi, bacteria and herbivores also make them undesirable asfood for humans. Certain crops artificially selected to for producing lowlevels of compounds, can make them more susceptible to insects anddisease and leads to more chemicals being used to protect crops
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Three principle groups of secondary metabolites:
1. Nitrogen-containing 2nd ary productsAlkaloids, biosynthesized from amino acids
2. Phenolic compounds:
Aromatic substances, via shikimic acid pathway or malonic acid
pathway
3. Terpenes:
lipid synthesized, from acetyl CoA or basic intermediates of
glycolysis
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5major subclasses: monoterpenes, sesquiterpenes,diterpense, triterpenes and polyterpenes
Synthesized from IPP (Isopentenyl pyrophosphate) andDMAPP (Dimethyallyl pyrophosphate)
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Monoterpenes (C10):
Important agents of insect toxicity
Plants contain mixtures of volatile monoterpenes and sesquiterpenes =ESSENTIAL OILS
Lamiaceae family: peppermint (monoterpene = menthol), lemon(monoterpene = limonene), basil and sage
Conifers (f.e. pine and fir): Resin monoterpenes accumulate in resinducts in needles, twigs and trunks = -pinene, B-pinene, limonene andmyrcene
Toxic to insects and beetles
Found in glandular hair on epidermis advertise toxicity of plant,repelling insects and other herbivores
Essential oils: extracted via steam distillation (commercially used toflavour foods and making perfumes)
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S
esquiterpene lactones (C15): Compositae family
Glandular hair
Characterized by lactone ring (cyclic ester)
Feeding repellants to herbivores and mammals = taste BITTER
Solanaceae
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Diterpenes (C20)
Toxins and feeding detergants
Resins, from pines and tropical leguminous trees contain abieticacid
Euphorbiaceae (Spurge family): diterpene esters of phorbol
When resins canals are pierced by insect feeding the outflow of
resin may physically block feeding and serve and chemicaldeterrent to continued predation
Phorbol type diterpenes tumor promoters in animals
Pacific yew (Taxus brevifolia) contain taxol anti-cancer drug
Abieticacid
Phorbol
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Triterpenes (C30)
Steroids
Found in plasma membranes
Phytoecdysones by insects disrupts molting and other
developmental processes often with lethal consequences Limonoids:
Bitter substances in citrus spp.
Most powerful deterrent to insect feeding from Neem tree(Azadirachta indica) from Africa or Asia
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Triterpenes (C30)
Cardenolides
Glycosides (compounds containing an attached sugar)
Bitter tasting extremely toxic to higher animals
Humans: dramatic effects on the heart muscle (influence onNa+/K+activated ATPases); regulated doses they strengthen the heartbeat.
Foxglove (Digitalis) cardenolides extracted to treat heart disease Digitoxigenin (aglycone sugarless triterpene portion of
naturally occuring digitanides)
Glycosides aglycone + sugar
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Triterpenes (C30)
Saponins Steroids and tripterpene glycosides
Soaplike properties: soapy lather when shaken with water
Both lipid-soluble (triterpene) and water-soluble (sugar) elemens inone molecule gives saponins detergent properties
Toxicity due to ability to form complexes with sterols
May interfere with sterol uptake from the digestive system or disruptcell membranes after absorption into bloodstream
Yam (Dioscorea villosa)
Yamogenin
Used as starting materials in synthesis of progesterone like compounds forbirth control pills.
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Polyterpenes ((C5)n)
rubber
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Functions:
1. Defense mechanisms2. Mechanical support in attracting pollinators and fruit
dispersers
3. Absorbing harmful ultraviolet radiation
4. Reducing the growth of nearby competing plants Synthesized from 2 different pathways
Shikimic acid pathway
COH converted to aromatic amino acids
In plants, fungi and bacteria but not animals
Phenylalanine Cinnamic acid Simple phenolics / lignin /flavonoids / condensed tannins
Phenylalanine ammonia lyase (PAL) catalyses formation ofphenylalanine to cinnamic acid activity increased by environmentalfactors, such as low nutrient levels, light, and fungal infection.
Malonic pathway
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Simple
Phenolic
Compounds
Furanocoumarins non toxic until activated by UV-ligth /sunlight.
Activated furanocoumarins insert themselves into double helixDNA bind to pyrimidine bases cytosine and thymine blockingtranscription and repair leading to cell death Umbelliferae (cellery, parsnip and cellery)
Allelopathic activity (inhibiting growth of other plants: cafeicacid and ferrulic acid From leaves roots and decaying litter release substances into
enviroment
Lignin: primary and secondary roles Most abundant after cellulose
Strengthening Bonds to cellulose and protein, reduces digestibility Blocks growth of pathogens and response to infection or
wounding
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Flavonoids Largest class of plant phenolics
15 carbons in a arrangement with 2 aromatic ringsconnected by a 3 carbon bridge
Fusion of 2 parts synthesized from 2 different pathways shikimic acid pathway and the malonic acid pathway
Anthocyanins Coloured flavonoids that attract animals for pollination and
seed dispersal (mutualism)
1 of 2 principles colored pigments flavonoids (othercarotenoids terpenoid compound accessory compounds inphotosynthesis yellow, orange and red)
Red, pink, purple, blue colors in plants
Anthocyanin anthocyanidins + sugars
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Anthocyanins Anthocyanidins:
Pelargonidin (organge red)
Cyanidin (Purplish red)
Delphinidin (Bluish purple)
Peonidin (Rosy red)
Petunidin (purple)
Anthocyanins and carotenoids responsible for variety ofcolours in plant kingdom.
Colour one type of signal to animal also monoterpenesprovide attractive scents.
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F
lavones and flavonols Absorb light at shorter wavelengths, not visible to human
eye
Visible to bees and insects may indicate the location ofpollen and nectar
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Isoflavonoids
Defense compounds synthesized immediately following infection byfungi or bacteria
Leguminosae
Tannins
Plant phenolic polymer
1st used to describe compounds that could convert raw animal hidesinto leather in the process known as tanning
Tannins bind to collagen proteins of animal hides, increasing resistanceto heat, water and microbes
2 categories:
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Tannins
1. Condensed tannins
2. Hydrolyzable tannins
Astringents taste due to binding of salivary proteins
General toxins that reduce growth and survivorship, most mammalsavoid, but humans often prefer certain level of astringency in tannincontaining foods apples, blackberries, tea and red wine
Inactivate herbivore digestive enzymes and create complexaggregates of tannins and plant proteins that are difficult to digest
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Nitrogen in structure
Alkaloids Poisonous if taken in sufficient quantity
Strychnine, atropine, coniine (poison hemlock)
Lower doses useful pharmacologically
Morphine, codeine, atropine and ephedrine Stimulants or sedatives
Cocaine, nicotine and caffeine
Mechanism of action:
1. Interfere with components of the NS, esp. chemicaltransmitters
2. Others affect membrane transport, protein, or miscellaneousenzyme activities
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Cyanogenic glycosides
Release poison hydrogen cyanide
Glucosinolates (mustard oil glycosides)
Also release volatile toxins
Cruciferae
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bitter principles release of gastrin
Release of gastrin increases: Gastric acid & pepsin secretions
Pancreatic digestive secretions
Intestinal juice production
Hepatic bile flow Hepatic bicarbonate production
Brunners glands secretions
Intrinsic factor secretinos insulin, glucagon & calcitonin
secretions Muscle tone of lower oesophageal sphincter
Muscle tone of stomach and small intestine
Cell division & growth of gastric & duodenal mucosa
Cell division & growth of pancreas
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Indications :
Increase appetite and digestive secretions
Enable body to digest,
assimilate vital nutrients
Eliminate wastes efficiently
Food
= nourishment also present immunological challenge
Low stomach secretions
enteric infections
Antigen penetration through gut wall (f.e. dysbiosis - candida,food allergies)
Autoimmune problem coinciding with depressed digestion
Stimulate the totality of digestive activity
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Stimulate the totality of digestive activity Protect gut tissue
Promote bile flow
Enhance pancreatic function
Tonics Nervous disorders and emotional disharmony
Also,
Bitter tonics
Hepatics Choleretics (improves amounts of secretions)
Cholagogues (stimulates gallbladder contraction toimprove secretions)
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Compositae family Especially useful in hypercholesterolaemia
Cautions:
Allergy to Compositae family
Contact dermatitis not oral ingestions
Cholelithiasis (gallstones)
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Compositae family
Relates spp A. annua,A. afra,A abrotanum etc
Aromatic bitter
Dyspepsia
Safety:
Contra-indicated in pregnancy
No longer than 4-6 wks
High doses
CNS toxin cause hallucinations & addictions
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Mustard Oil Glycosides
G
lycosides / glucosilinates Cruciferae family
Mostly used externally as rubefacients (increases local bld flow) orvesicants
Goitrogenic (substances that suppress the function of the thyroid gland
by interfering with iodine uptake) if consumed in large amounts Miscellaneous Pungent Constituents
Pungent alkaloids: capsaicin (Capsicum spp)
Volatile oils (Zingiber off)
Sulphur-containing constituents (Allium spp)
Rubefacient, vesicant, counter-irritants (therapeutic inflammation,without destructive inflammatory agents)
Stimulate circulation at a local level
Stimulate stomach acid production
Carminative
Disinfects lungs and expectorates
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Mixture of fragrant compounds Extracted by steam distillation
Wide range of pharmacological activities
Antimicrobial and spasmolytic, carminative (mint, sage,rosemary, cardamon, dill), diuretics (juniper), expectorant(aniseed), sedative (lavender), anxiolytic (melissa),anaesthetic (clove), analgesic (lemongrass), rosemary(stimulant activity), diaphoretic, anti-inflammatory, anti-
ulcer and oestrogenic activities
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Tea tree
Chamomile
Lemon balm
Buchu
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Plant pigments Flavus = pigment
Anti-oxidant activity, reducing capillary fragilityand permeability, duiretcs, anti-spasomodic, anti-inflammatory, antiseptic
Yarrow
Elder
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Resins (Pinus spp), oleo-resins (Pinus spp),Oleo-gum-resins and gum resins (Commiphoramolmol, Boswelia spp), balsamic resins (Styrax
spp) and balsams (Myroxylon pereira) Uses: antiseptic, anti-inflammatory
Commiphora molmol
Potentilla erecta
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Treating wounds and burns
Haemostatics
Anti-inflammatory
Especially usefull in diarrhoea
Potentilla erecta
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Bulk laxatifes
Inflammations in the respiratory, urinary andGIT
Ulmusfulva
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Highly toxic cause lysis of bld cells Sapo = soap
Glycosides
On injections cause lysis of bld cells, haemolysis and are
highly toxic On oral ingestion hydrolysi occus splittin the glycosie into
its sugar and aglycone / sapogenin. Sapogenin does notposses the haemolytic properties and is safe.
2 classes:1. Steroidal saponins structural relationship to steroidal
hormones, cardioactive glycosides and vitamin D
Dioscin from Dioscorea villosa used to manufacture sex
hormones
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Triterpenoid saponins
Trigonella dioscin and diosgenine may also act as a precurosr tofemale hormones and adrenal hormones
Glycyrrhiza glabra saponins mimic adrenocorticotrophichomrone and potentiate glucocorticoid, prgesterone andaldosterone actigity by inhibiting their metabolism
Anti-inflammatory (Solidago candensis,stellaria media) Diuretic (Betula spp)
Antispasmodic (Nigella sativa)
Adaptogens (Glycyrrhiza glabra, panax ginseng)
Stimulating expectorants (Lobelia inflata, verbascu
m thapsu
s, Viola spp,Glycyrrhiza glabra)
Treatment of vascular disorders (Centella asiatica,Achilleamillefolium)
Used to increase bioavailability of other components
Facilitates absorption of nutrients.