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Phytochemicals John Parry, Ph.D. Rm 229, M.T. Carter Bldg Agricultural Research Station Phone: (804) 524-5957 Email: jparr...
Tocopherols (Vitamin E) <ul><li>Eight vitamers: </li></ul><ul><li>(           ) tocopherol </li></ul><ul><li>(      ...
Carotenoids <ul><li>Include:   -carotene </li></ul><ul><li>They are not direct antioxidants </li></ul><ul><ul><li>They qu...
Essential Fatty Acids <ul><li>Linoleic acid (18:2n6) </li></ul><ul><li>Linolenic acid (18:3n3) </li></ul><ul><li>DHA (22:6...
Phytosterols <ul><li> -sitosterol,   -7 avenosterol, stigmasterol, etc. </li></ul><ul><li>These molecules resemble chole...
Phenolic Antioxidants <ul><li>Phenolic compounds have been shown to have antioxidant properties  in vitro  when compared v...
Phenolic Antioxidants <ul><li>Are gradually losing popularity among scientist in the field while still publically demanded...
Free Radicals <ul><li>Biologically relevant free radicals: </li></ul><ul><ul><li>Superoxide anion – O 2    _ </li></ul></...
Enzymatic Antioxidants <ul><ul><li>Superoxide dismutase – 2O 2    _     O 2  + H 2 O 2 </li></ul></ul><ul><ul><ul><li>Gr...
Free Radicals <ul><li>Other biologically relevant damaging molecules related to free radicals: </li></ul><ul><ul><li>Hydro...
Antioxidants: Synthesized <ul><li>BHA – Butylated hydroxy anisole </li></ul><ul><li>BHT – Butylated hydroxy toluene </li><...
Enzymatic Antioxidants <ul><ul><li>Superoxide dismutase – 2O 2    _     O 2  + H 2 O 2 </li></ul></ul><ul><ul><li>Catala...
Antioxidants: Non-Enzymatic <ul><li>Ascorbic Acid </li></ul><ul><li>Tocopherols (8 isoforms) </li></ul><ul><li>Carotenoids...
Antioxidants: Non-Enzymatic <ul><li>Tocopherols (8 isoforms) </li></ul><ul><li> -,   -,   -,   -Tocopherol </li></ul><...
Antioxidants: Non-Enzymatic <ul><li>Vitamin E (  -Tocopherol) is the most effective antioxidant of the 8 isoforms </li></...
Antioxidants: Non-Enzymatic <ul><li>Vitamin A and Carotenoids </li></ul><ul><li>Beta carotene has 2 beta ionone ring makin...
Antioxidants: Non-Enzymatic <ul><li>Over 700 carotenoids have been identified comprised of 2 structural groups </li></ul><...
Antioxidants: Non-Enzymatic <ul><li>Glutathione </li></ul><ul><ul><li>(GSH) – reduced form (90%) </li></ul></ul><ul><ul><l...
Antioxidants: Non-Enzymatic <ul><li>Glutathione </li></ul><ul><ul><li>Can reduce the oxidized form of vitamin E </li></ul>...
Antioxidants: Non-Enzymatic <ul><li>Phenolic compounds </li></ul><ul><ul><li>Exist in virtually all plant foods </li></ul>...
Antioxidant Basic Phenol Radical Resonance for Stability
Phenolic Antioxidants
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Antioxidants and phytochemical talk 05 07-11

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Antioxidants and phytochemical talk 05 07-11

  1. 1. Phytochemicals John Parry, Ph.D. Rm 229, M.T. Carter Bldg Agricultural Research Station Phone: (804) 524-5957 Email: jparry@vsu.edu
  2. 2. Tocopherols (Vitamin E) <ul><li>Eight vitamers: </li></ul><ul><li>(     ) tocopherol </li></ul><ul><li>(     ) tocotrienol </li></ul><ul><li>Prevent peroxyl radical propagation in lipids </li></ul><ul><li>The most conserved is  -tocopherol </li></ul><ul><li>Found mainly in oils (wheat germ, corn) </li></ul>
  3. 3. Carotenoids <ul><li>Include:  -carotene </li></ul><ul><li>They are not direct antioxidants </li></ul><ul><ul><li>They quench the energy of singlet O 2 which is more reactive than triplet O 2 </li></ul></ul><ul><li>Some carotenoids can be converted to vit. A </li></ul><ul><li>Orange colored foods </li></ul><ul><ul><li>They were found to be very high in pumpkin seeds in a previous study, carrots, and sweet potatoes. </li></ul></ul>
  4. 4. Essential Fatty Acids <ul><li>Linoleic acid (18:2n6) </li></ul><ul><li>Linolenic acid (18:3n3) </li></ul><ul><li>DHA (22:6n3) </li></ul><ul><li>EPA (20:5n3) </li></ul><ul><li>Some of these can be found in plant foods such as flax seed oil, basil seed oil, cold water fish </li></ul><ul><li>Other sources: </li></ul>
  5. 5. Phytosterols <ul><li> -sitosterol,  -7 avenosterol, stigmasterol, etc. </li></ul><ul><li>These molecules resemble cholesterol and have been shown to decrease cholesterol levels </li></ul>
  6. 6. Phenolic Antioxidants <ul><li>Phenolic compounds have been shown to have antioxidant properties in vitro when compared vitamin E and C </li></ul><ul><li>The French Paradox </li></ul><ul><ul><li>Initially the bioflavonoid content was the reason </li></ul></ul><ul><li>Recently resveratrol has been suggested as the reason for the paradox </li></ul>
  7. 7. Phenolic Antioxidants <ul><li>Are gradually losing popularity among scientist in the field while still publically demanded </li></ul><ul><li>Jeff Moore </li></ul>
  8. 8. Free Radicals <ul><li>Biologically relevant free radicals: </li></ul><ul><ul><li>Superoxide anion – O 2  _ </li></ul></ul><ul><ul><li>Hydroxyl – OH  (very reactive) </li></ul></ul><ul><ul><li>H 2 O 2 – not a free radical but very reactive </li></ul></ul><ul><ul><li>Peroxyl – ROO  </li></ul></ul>
  9. 9. Enzymatic Antioxidants <ul><ul><li>Superoxide dismutase – 2O 2  _  O 2 + H 2 O 2 </li></ul></ul><ul><ul><ul><li>Group of isozymes </li></ul></ul></ul><ul><ul><ul><li>Kcat (turnover rate) 1 x 10 7 per second </li></ul></ul></ul><ul><ul><li>Catalase – H 2 O 2  2 H 2 O + O 2 </li></ul></ul><ul><ul><ul><li>Kcat 1 x 10 6 per second </li></ul></ul></ul><ul><ul><li>Glutathione peroxidase – LOO   LOH </li></ul></ul><ul><ul><ul><li>Group of isozymes </li></ul></ul></ul>
  10. 10. Free Radicals <ul><li>Other biologically relevant damaging molecules related to free radicals: </li></ul><ul><ul><li>Hydrogen peroxide – H 2 O 2 </li></ul></ul><ul><ul><li>Fenton reaction </li></ul></ul><ul><ul><ul><li>Fe (II) + H2O2  Fe (III) + OH _  + OH  </li></ul></ul></ul><ul><ul><li>Peroxynitrite – ONOO _ </li></ul></ul><ul><ul><ul><li>Formed by the reaction of nitrite and O 2  _ </li></ul></ul></ul><ul><ul><ul><li>Reacts with CO 2 forming a CO 3  , and NO 2  </li></ul></ul></ul><ul><ul><li>Peroxynitrous acid – ONOOH (pKa ~ 6.8) </li></ul></ul><ul><ul><ul><li>Forms OH  and NO 2  </li></ul></ul></ul>
  11. 11. Antioxidants: Synthesized <ul><li>BHA – Butylated hydroxy anisole </li></ul><ul><li>BHT – Butylated hydroxy toluene </li></ul><ul><li>TBHQ – tert-Butylhydroxyquinone </li></ul><ul><li>All 3 of these are lipophilic (fat soluble) </li></ul><ul><li>These are added to foods to protect susceptible fatty acids and fat soluble vitamins </li></ul><ul><li>Health concerns regarding synthesized antioxidants: </li></ul><ul><li>cause cancer in animal studies </li></ul><ul><li>damage DNA </li></ul>
  12. 12. Enzymatic Antioxidants <ul><ul><li>Superoxide dismutase – 2O 2  _  O 2 + H 2 O 2 </li></ul></ul><ul><ul><li>Catalase – H 2 O 2  2 H 2 O + O 2 (Kcat 1 x 10 7 ) </li></ul></ul><ul><ul><li>Glutathione peroxidase – LOO   LOH </li></ul></ul><ul><ul><li>These enzymes and enzyme systems are continually operating but genetic expression is upregulated during oxidative stress </li></ul></ul>
  13. 13. Antioxidants: Non-Enzymatic <ul><li>Ascorbic Acid </li></ul><ul><li>Tocopherols (8 isoforms) </li></ul><ul><li>Carotenoids </li></ul><ul><li>Phenols and Polyphenols (found in plants) </li></ul><ul><li>Glutathione </li></ul><ul><li>Lipoic acid (a fatty acid with disulfide antioxidant) </li></ul><ul><li>Coenzyme Q (involved in electron transport chain) </li></ul><ul><li>Melatonin ( </li></ul><ul><li>Bilirubin (a breakdown product of red blood cells) </li></ul><ul><li>Uric acid </li></ul>
  14. 14. Antioxidants: Non-Enzymatic <ul><li>Tocopherols (8 isoforms) </li></ul><ul><li> -,  -,  -,  -Tocopherol </li></ul><ul><li> -,  -,  -,  - Tocotrienol </li></ul><ul><li> -Tocopherol </li></ul><ul><li> -Tocotrienol </li></ul>
  15. 15. Antioxidants: Non-Enzymatic <ul><li>Vitamin E (  -Tocopherol) is the most effective antioxidant of the 8 isoforms </li></ul><ul><ul><li>Vitamin E protects lipid membranes from oxidation of unsaturated fatty acids </li></ul></ul><ul><ul><ul><li>Most susceptible tissues: </li></ul></ul></ul><ul><ul><li>It is stored in lipid membranes, adipose tissue liver, heart, muscle, and adrenal glands </li></ul></ul><ul><ul><li>It is thought to be regenerated by vitamin C </li></ul></ul>
  16. 16. Antioxidants: Non-Enzymatic <ul><li>Vitamin A and Carotenoids </li></ul><ul><li>Beta carotene has 2 beta ionone ring making it capable of forming 2 vitamin A molecules </li></ul>
  17. 17. Antioxidants: Non-Enzymatic <ul><li>Over 700 carotenoids have been identified comprised of 2 structural groups </li></ul><ul><ul><li>Some hydrocarbon carotenes </li></ul></ul><ul><ul><ul><li> -carotene </li></ul></ul></ul><ul><ul><ul><li> -carotene (1 vitamin A; has one ionone ring) </li></ul></ul></ul><ul><ul><ul><li>Lycopene </li></ul></ul></ul><ul><ul><li>Some oxygenated xanthophylls </li></ul></ul><ul><ul><ul><li> -cryptoxanthin </li></ul></ul></ul><ul><ul><ul><li>Lutein </li></ul></ul></ul><ul><ul><ul><li>Zeaxanthin (corn) </li></ul></ul></ul><ul><ul><li>The mechanism of antioxidant protection from the carotenoids is not from free radical scavenging but from the quenching of singlet oxygen ( 1 O 2 ) </li></ul></ul>
  18. 18. Antioxidants: Non-Enzymatic <ul><li>Glutathione </li></ul><ul><ul><li>(GSH) – reduced form (90%) </li></ul></ul><ul><ul><li>(GSSG) – oxidized form (10%) </li></ul></ul><ul><ul><li>Consists of gly, cys, and glu </li></ul></ul><ul><ul><li>Thiol group is active </li></ul></ul><ul><ul><li>Used by glutathione peroxidase to reduce peroxides </li></ul></ul>
  19. 19. Antioxidants: Non-Enzymatic <ul><li>Glutathione </li></ul><ul><ul><li>Can reduce the oxidized form of vitamin E </li></ul></ul><ul><ul><li>Is made in every cell of the body but primarily the liver </li></ul></ul><ul><ul><li>Glutathione reductase is continually active and is inducible when subjected to oxidative stress </li></ul></ul><ul><ul><li>NADPH can reduce GSSG to GSH </li></ul></ul>
  20. 20. Antioxidants: Non-Enzymatic <ul><li>Phenolic compounds </li></ul><ul><ul><li>Exist in virtually all plant foods </li></ul></ul><ul><ul><li>Very highly concentrated in spices </li></ul></ul><ul><li>Phenolic acids </li></ul><ul><ul><ul><li>Gallic acid, syringic acid, p-OH benzoic acid, vanillic acid </li></ul></ul></ul><ul><li>Hydroxycinnamic acids </li></ul><ul><ul><ul><li>Ferulic acid, p-coumaric acid, caffeic acid </li></ul></ul></ul><ul><li>Polyphenolic acids </li></ul><ul><ul><ul><li>Anthocyanins, proanthocyanins </li></ul></ul></ul>
  21. 21. Antioxidant Basic Phenol Radical Resonance for Stability
  22. 22. Phenolic Antioxidants

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