Pro-oxidant activities Antioxidant

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antioxidants reducing agents can act pro-oxidants. example, vitamin c has antioxidant activity when reduces oxidizing substances such hydrogen peroxide, however, reduce metal ions generate free radicals through fenton reaction.



2 fe + ascorbate → 2 fe + dehydroascorbate

2 fe + 2 h2o2 → 2 fe + 2 oh· + 2 oh



the relative importance of antioxidant , pro-oxidant activities of antioxidants area of current research, vitamin c, exerts effects vitamin oxidizing polypeptides, appears have antioxidant action in human body. however, less data available other dietary antioxidants, such vitamin e, or polyphenols. likewise, pathogenesis of diseases involving hyperuricemia involve uric acid s direct , indirect pro-oxidant properties.


that is, paradoxically, agents considered antioxidants can act conditional pro-oxidants , increase oxidative stress. besides ascorbate, medically important conditional pro-oxidants include uric acid , sulfhydryl amino acids such homocysteine. typically, involves transition-series metal such copper or iron catalyst. potential role of pro-oxidant role of uric acid in (e.g.) atherosclerosis , ischemic stroke considered above. example postulated role of homocysteine in atherosclerosis.


negative health effects

some antioxidant supplements may promote disease , increase mortality in humans under conditions. hypothetically, free radicals induce endogenous response protects against exogenous radicals (and possibly other toxic compounds). free radicals may increase life span. increase may prevented antioxidants, providing direct evidence toxic radicals may mitohormetically exert life extending , health promoting effects.








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