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Phytochemical community open house dalhousie university truro campus


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Phytochemicals are broad & diverse group of compounds that are produced & accumulated in plants. Phytochemical-rich foods include: fruits & vegetables, some cocoa products, as well as whole grains, beverages such as tea & wine. Phytochemicals can alter metabolic & cellular processes.

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Phytochemical community open house dalhousie university truro campus

  1. 1. PHYTOCHEMICALS 1 Soheila Abachi Summer 2014
  2. 2. Dietary phytochemicals Phytochemicals are broad & diverse group of compounds that are produced & accumulated in plants Phytochemical rich foods include: fruits & vegetables, some cocoa products, as well as whole grains, beverages such as tea & wine Phytochemicals can alter metabolic & cellular processes 2
  3. 3. Dietary phytochemicals Most dietary studies indicate that diets rich in phytochemicals are associated with improved health & provide protection against chronic diseases, or in positive direction alter chronic disease markers 3
  4. 4. How do phytochemicals work? Some possible actions: Antioxidant : Most phytochemicals have antioxidant activity & protect our cells against oxidative damage, reduce risk of developing certain types of cancer Phytochemicals with antioxidant activity: allyl sulfides (onions, leeks, garlic), carotenoids (fruits, carrots), polyphenols including flavonoids (fruits, vegetables, tea) 4
  5. 5. Hormonal action: Isoflavones, found in soy, imitate human estrogens and help to reduce menopausal symptoms & osteoporosis. Stimulation of enzymes: Indoles, found in cabbages, stimulate enzymes that make estrogen less effective & could reduce risk for breast cancer. Other phytochemicals, which interfere with enzymes, are protease inhibitors (soy and beans), terpenes (citrus fruits & cherries). 5
  6. 6. Interference with DNA replication: Saponins found in beans interfere with replication of cell DNA, thereby preventing multiplication of cancer cells. Capsaicin, in hot peppers, protects DNA from carcinogens Anti-bacterial effect: allicin from garlic has anti- bacterial properties 6
  7. 7. Physical action: Some phytochemicals bind physically to cell walls thereby preventing adhesion of pathogens to human cell walls. Proanthocyanidins are responsible for anti-adhesion properties of cranberry Consumption of cranberries will reduce risk of urinary tract infections & will improve dental health 7
  8. 8. Natural antioxidants & their health promoting effects 8
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  12. 12. Antioxidants (Aox) – an overview Molecules capable of reducing causes or effects of oxidative stress Oxidative stress caused by environmental factors, disease, infection, inflammation, aging (ROS production) Body produces some endogenous antioxidants, but dietary antioxidants provide additional defense 12
  13. 13. Antioxidants – an overview ROS or “reactive oxygen species”: free radicals & other oxygenated molecules resulting from these factors 13 Chronic Injury Cancer, atherosclerosis, CVD, cataracts, immune dysfunction, Alzheimer´s disease, age-related macular degeneration, rheumatoid arthritis, aging, etc. 13 Oxidative Stress
  14. 14. Antioxidants – an overview Most AOx donate an electron to Free radicals (FR) without becoming FR themselves & stops chain reaction 14
  15. 15. 15 Sources of antioxidants in diet
  16. 16. Vitamin E, Vitamin C, β- Carotene, Flavonoids Polyphenols Flavonoids Non- Flavonoids Flavonols→ Quercetin Flavones Flavanols→ Catechin Flavanones Stilbenes → Resveratrol Iso-Flavonoids Anthocyanidins Vitamins A E C Phenolic alcohols Hydroxybenzoic acids Hydroxycinnamic acids Lignans Dietary antioxidants Most common dietary AOx
  17. 17. Red wine, Cranberries & blueberries (tannins, resveratrol, flavonoids) Strawberries (ellagic acid, ellagitannins) Tea, Chocolate (EGCG & other catechins, tannins) Onions (quercetin) Spinach & leafy greens (lutein & zeaxanthin) Eggs (lutein) Citrus fruits (Vitamin C) Plant oils (Vitamin E & omega-3) 17
  18. 18. Define antioxidant “a substance that opposes oxidation or inhibits reactions promoted by oxygen or peroxides” “synthetic or natural substances that prevent or delay deterioration of a product, or capable of counteracting damaging effects of oxidation in animal tissues” 18
  19. 19. Define antioxidant “a substance that significantly decreases adverse effects of reactive species such as ROS or RNS on normal physiological function in humans 19
  20. 20. Different types of AOx →different AOx Mechanisms 20 Proper AOx: interrupt propagation of autoxidation chain reaction Preventive AOx: inhibitors of FR oxidation reactions Singlet Oxygen eliminators: e.g. carotenes Reducing agents: convert hydroperoxides into stable components in a non-radical way e.g. thiols and sulfides. Synergists of proper AOx: increase activity of chain-breaking AOX in a mixture e.g. citric acid Metal chelators: convert pro-oxidants (especially iron or copper derivatives) into stable products (e.g. Quercetin, tannins) Inhibition of pro- oxidative enzymes
  21. 21. Free radicals & ROS “Reactive Oxygen Species” (ROS): highly reactive free radicals ROS form as result of stress, inflammation, human body’s natural defenses & mostly are formed in mitochondria, by phagocytes & peroxisomes Target tissue, proteins, lipids & DNA 21
  22. 22. Antioxidants? Prevent formation of ROS & chelate metals Scavenge/remove ROS before they damage important bio-molecules 22
  23. 23. 3 major classes of phytochemicals Terpenoids Alkaloids Phenolics 23
  24. 24. “polyphenolic” antioxidants found in plants 24 O OH OH OR HO OH quercetin, a "flavonol" O O OH OH OR HO OH catechins OH HO OH resveratrol, a "stilbene" On a molecular level, these compounds “absorb” harmful free radicals & chelate pro-oxidant metal ions Modulate cellular biochemical reactions & expression of genes and proteins associated with oxidative stress
  25. 25. 25 1) Simple sugars + phenol groups 2) Lignin & furanocoumarin: inhibit herbivore/pathogen 3) Lignin: mechanical support 4) Lignan: inhibit fungal growth, insect anti-feedent 5) Anthocyanin: pollinators 6) Flavone / flavonol: absorb UV 7) Phenolic acid: reduce competing plant growth 8) Tannin: protein/enzyme inactivation How Phenolics protect plants?
  26. 26. 26 1) Analogues of cellular signals, substrates 2) Induce prostaglandin formation 3) Enzyme inhibitor 4) Estrogenic properties: stilbenes, isoflavones 5) DNA alkylation: furanocoumarin 6) Denaturing effect, hydroxyl groups form hydrogen/ion bonds with protein How flavonoids protect plants?
  27. 27. Flavonoids Flavonoids → most common group of plant phenolics → +4000 identified in plants → Share a common structure (2 Benzene rings and a central pyran ring) which determines their AOx functioning 27 Flavonols Flavanols Flavonones Anthocyanins Isoflavones Flavones
  28. 28. Health promotion by Flavonoids Many flavonoids act as antioxidants May protect against cancers and heart disease by this mechanism More evidence is needed before any claims can be made for flavonoids themselves as the protective factor in foods Particularly when they are extracted from foods or herbs and sold as supplement 28
  29. 29. 29 1) Phenolic acids 2) Stilbenes 3) Flavonoids: flavonols, anthocyanins, flavan-3-ols 4) Lignan 5) Tannins: hydrolysable & condensed Berry fruit phenolics classification
  30. 30. Bluberries Brain berries Promote brain function & prevent the effects of aging reducing risks of some diseases, including inflammation & certain cancer Promote urinary tract health 30
  31. 31. Strawberries Contain Phenolic Acids & Phenylpropanoids Aromatic secondary metabolites Substitution with carboxyl or hydroxyl groups generate a bundle of compounds 31
  32. 32. Cranberry Contain Phenolic Acids, Proanthocyanidins, Anthocyanins, Flavonoids, Triterpenoids These compounds have shown: Antioxidant, anti-inflammatory, & anti-cancer effects 32
  33. 33. 1) Isoprene gas: hi-temp., photo-protection 2) Monoterpene: Menthone, α & β-pinene, insect toxin/ repellent 3) Triterpenoid: cardiac glycoside, highly toxic 4) Glycosylated triterpenoid: saponin, disrupt fungus cell membrane 33 How Terpenes protect plants?
  34. 34. 1) Isoprene gas: hi-temp., photo-protection 2) Monoterpene: Menthone, α & β-pinene, insect toxin/ repellent 3) Triterpenoid: cardiac glycoside, highly toxic 4) Glycosylated triterpenoid: saponin, disrupt fungus cell membrane 34 How Terpenes protect plants?
  35. 35. 35 1) Highly hydrophobic, interact with bio-membrane 2) Increase fluidity of membrane, uncontrolled efflux of ion/metabolite 3) modulate membrane protein/receptors, cell leakage/death 4) Analogues to natural substrates 5) Isoprene units 6) Primary metabolites (plant hormone) Gibberellic acid, Carotenoid pigment How Terpenes protect plants?
  36. 36. Harvest midsummer <1 cm in diameter Very dark purple, almost black Glossy Skin Grossulariaceae Ribes R. Nigrum Rich in Vitamin C, E Phosphorus, Potassium
  37. 37. Harvest early to late summer <1.6 cm in diameter Dark purple Powdery epicuticular wax Ericaceae Vaccinium V. corymbosum Rich in Vitamin C, K Manganese, Copper
  38. 38. Harvest early to midfall 1-2.5 cm in diameter Dark red to almost black Hard, shiny skin Ericaceae Vaccinium V. Macrocarpon Rich in Vitamin C, E, K Manganese
  39. 39. Harvest late summer to fall 0.6–1 cm in diameter Red Shiny skin Ericaceae Vaccinium V. vitis-idaea Rich in Vitamin C, E, K Manganese
  40. 40. Harvest early summer 1 cm in diameter Purple-blue Powdery epicuticular wax Caprifoliaceae Lonicera L. caerulea Rich in Vitamin C, E Potassium Calcium Magnesium Phosphorus