Antioxidants

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

1. Dr Anu Chandran
Department of pharmacology
Trivandrum medical college

3. *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

5. *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

6. *A free radical is formed when a
covalent bond between entities
(atoms) is broken and one electron
remains with each newly formed
atom

7.  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)

8. *Ionizing radiations,
*Heavy metals,
* Cigarette,
* Alcohol intake
*Pollution
*Pesticides
*Insecticides
*

10. * Oxidize the biomolecules leading to
tissue injury and cell death.
*After initiation, the chain can
propagates to form a vicious cycle
inducing further damage.

11. *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.

12. *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.

14. Substances that neutralize free radicals
or their actions
Limit free radical formation
Destroy free radicals
Stimulate antioxidant enzyme
activity

16. Endogenous enzymatic anti oxidants are constituted
by three major enzyme groups
*Superoxide Dismutase
*Catalase
*Peroxidase

19. *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.

22. *α tocoferol has the highest vit
E activity
Dietary source
*Wheat germ oil, vegetable
seed oil, nuts, egg yolk, peas.

23. 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)

25. Dietary source
*Citrus fruits
*Tomatoes
*Potatoes
*Green Chillies
*Cabbage

26. *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)

27. *Biologically active
*Naturally occurring chemical
compounds
*Found in plants
*Act as natural defense for
host plants
*Provide color and flavor

28. *Beta carotene
*Lycopene
*Limonoids

29. *Precursor of vitamin A
*ANTIOXIDANT

30. *RED color – tomato , water
melon ,papaya,gauva
•LIMONOIDS
– citrus fruits

31. *Sulphur containing phytochemicals
Cruciferous vegetables like
braccoli,cabbage ,watercres
Onion ,garlic
*Antioxidant role - anticancer role
especially for lung and GIT cancer

32. *Blue berries
,grapes,cherries,red apple
*Green tea black tea
*Soyabeans

33. *LOO˙ + FL - OH LOOH + FL - O˙
*Flavonoid phenonyl radical

34. *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)

35. *Blue green algae
*Good source of SOD ,B carotene and B
complex vitamin
*Most powerfull food on earth

36. *Fat soluble antioxidant
*Present in mitochondria
*Decline with age
*100 to 200 mg/day
*Benefit in PD and CHF

38. 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

39. c) Desferoxamine,
Cerulloplasmin
*Binds free Fe2+, binds superoxide
anion
*Inhibit iron dependant lipid
peroxidation
*Used in AD, RA, reperfusion injury

40. 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)

41. f)Xanthine oxidase inhibitors
(Allopurinol, Oxypurinol)
*Xanthine oxidase generates
super oxide free radicals from
reduced flavins
*Important in reperfusion
injury after ischemia

42. *NSAIDs
*ACE Inhibitors
*CCBs
*Selegiline