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presentation on antioxidants, they are the priority nowadays , presentation includes wide variety of antioxidants and their mechanism of action

Publié dans : Santé & Médecine
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  1. 1. Dr Anu Chandran Department of pharmacology Trivandrum medical college
  2. 2. *Definition: a free radical is any atom (e.g. oxygen, nitrogen) with at least one unpaired electron in the outermost shell, and is capable of independent existence
  3. 3. *Unstable molecule *They seek out to capture electrons to neutralize themselves *Another free radical formed *Chain of reaction sets in *Within seconds thousands of free radicals formed
  4. 4. *A free radical is formed when a covalent bond between entities (atoms) is broken and one electron remains with each newly formed atom
  5. 5.  Electron transport chain drug metabolism by CYPs phagocytosis. Transition metals present in the body ( e.g. Fe, Cu etc.),. (they have variable oxidation numbers ,so can accept or donate electons)
  6. 6. *Ionizing radiations, *Heavy metals, * Cigarette, * Alcohol intake *Pollution *Pesticides *Insecticides *
  7. 7. * Oxidize the biomolecules leading to tissue injury and cell death. *After initiation, the chain can propagates to form a vicious cycle inducing further damage.
  8. 8. *Destroys PUFA of cell membranes *Destabilises membrane receptors *Inactivate enzymes *Breaks DNA strands * involved in physiological processes like ageing and pathologically in diseases with multi organ involvement.
  9. 9. *Carcinogenesis (due to DNA damage) *Rheumatiod arthritis *Amyloidosis *CNS – Parkinson’s disease *CVS – Myocardial infarction, Atherosclerosis.(LDL oxidatin)endothelial dysfuction *GIT – Peptic ulcer, Cirrhosis, Pancreatitis *Renal – Nephrotoxicity due to glomerulonephritis / Heavy metals. *Respiratory – asthma *Vision – Cataract,Retinopathy.
  10. 10. Substances that neutralize free radicals or their actions Limit free radical formation Destroy free radicals Stimulate antioxidant enzyme activity
  11. 11. Endogenous enzymatic anti oxidants are constituted by three major enzyme groups *Superoxide Dismutase *Catalase *Peroxidase
  12. 12. *An imbalance in the oxidant to anti oxidant levels lead to a condition termed oxidative stress. *increased generation and impaired degradation of the free radicals. *Impaired degradation in conditions like amyotrophic lateral sclerosis (ALS), where there are presumed decreases in superoxide dismutase.
  13. 13. *α tocoferol has the highest vit E activity Dietary source *Wheat germ oil, vegetable seed oil, nuts, egg yolk, peas.
  14. 14. Physiological role as anti-oxidant *Prevents oxidation of coenzyme Q * protects poly unsaturated fatty acids from oxidative break down( lipid peroxidation) *tocopherol phenoxyl radical *Major chain breaking antioxidant *Protection against cancer, coronary artery disease, AD and cataracts. *400 IU to 800 IU( daily recommentation)
  15. 15. Dietary source *Citrus fruits *Tomatoes *Potatoes *Green Chillies *Cabbage
  16. 16. *Reacts with H2O2, peroxide and super oxide to get oxidised to dehydroascorbate. *Carcinogenic effect of tobacco through nitrosamines are inhibited by Vit C & E *Deficiency can predispose to atherosclerosis and carcinogenicity. *60 mg ( daily recommentation)
  17. 17. *Biologically active *Naturally occurring chemical compounds *Found in plants *Act as natural defense for host plants *Provide color and flavor
  18. 18. *Beta carotene *Lycopene *Limonoids
  19. 19. *Precursor of vitamin A *ANTIOXIDANT
  20. 20. *RED color – tomato , water melon ,papaya,gauva • LIMONOIDS – citrus fruits
  21. 21. *Sulphur containing phytochemicals Cruciferous vegetables like braccoli,cabbage ,watercres Onion ,garlic *Antioxidant role - anticancer role especially for lung and GIT cancer
  22. 22. *Blue berries ,grapes,cherries,red apple *Green tea black tea *Soyabeans
  23. 23. *LOO˙ + FL - OH LOOH + FL - O˙ *Flavonoid phenonyl radical
  24. 24. *Act as phytoestrogen *Bind to estrogen receptors *Actions Increase bone density Decrease serum cholesterol Decrease post cancer prostrate growth Decrease hormone dependent cancer( anti estrogen effect)
  25. 25. *Blue green algae *Good source of SOD ,B carotene and B complex vitamin *Most powerfull food on earth
  26. 26. *Fat soluble antioxidant *Present in mitochondria *Decline with age *100 to 200 mg/day *Benefit in PD and CHF
  27. 27. a. N acetyl cysteine – glutathione precursor b. Ebselen – congener of glutathione * Both augment endogenous glutathione peroxidase activity * Anti oxidant effect of n acetyl cysteine is used in paracetamol poisoning
  28. 28. c) Desferoxamine, Cerulloplasmin *Binds free Fe2+, binds superoxide anion *Inhibit iron dependant lipid peroxidation *Used in AD, RA, reperfusion injury
  29. 29. d) Selenium *Enhances the antioxidant effect of Vit E *Promotes synthesis of glutathione peroxidase *Immunostimulant e) Mn,Zn, Cu, Cr *Also augments the synthesis of anti oxidant enzymes (SOD, GP, Catalase)
  30. 30. f)Xanthine oxidase inhibitors (Allopurinol, Oxypurinol) *Xanthine oxidase generates super oxide free radicals from reduced flavins *Important in reperfusion injury after ischemia
  31. 31. *NSAIDs *ACE Inhibitors *CCBs *Selegiline