PMID: 15374318Nov 1, 1993Paper

High concentrations of antioxidants may not improve defense against oxidative stress

Archives of Gerontology and Geriatrics
G Cao, R G Cutler

Abstract

It is often assumed that the oxygen radical defense could be further improved by higher concentration of antioxidants. But this has not been demonstrated over a wide range of concentrations. There are different types of oxygen radicals produced in the body and the antioxidant protection against them may not positively related to their concentrations. We report here that by using H(2)O(2) with Cu(2+) as an hydroxyl-radical generator in vitro, ascorbic acid shows no oxygen-radical absorbing capacity. We also found that the net hydroxyl-radical absorbing capacity of a water soluble alpha-tocopherol analogue (Trolox) and uric acid increases with concentration only when the concentration is lower than the normal value found for alpha-tocopherol and uric acid in human serum. At higher concentrations, the hydroxyl-radical absorbing capacity of the alpha-tocopherol analogue and uric acid decreases. The mechanism involved in the decrease of hydroxyl radical absorbance capacity of Trolox and uric acid at high concentration may be related to their reaction with hydroxyl radicals or other oxygen radicals produced in the presence of both H(2)O(2) and Cu(2+). This kind of reaction could lead to the formation of additional many Trolox or uric...Continue Reading

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Citations

Jan 1, 1996·Archives of Gerontology and Geriatrics·G CaoR L Prior
Oct 16, 1999·Fertility and Sterility·E T DonnellyS E Lewis
Jan 1, 1997·Free Radical Biology & Medicine·G CaoR L Prior
Jan 1, 2011·Animal : an International Journal of Animal Bioscience·J-H HuQ-W Li
Jan 1, 1995·Journal of Sports Sciences·P M Clarkson
Dec 31, 1997·American Journal of Respiratory and Critical Care Medicine·M RautalahtiJ K Huttunen
Apr 14, 2005·Theriogenology·Elizabeth BreiningerMartha T Beconi
Oct 3, 2018·Zygote : the Biology of Gametes and Early Embryos·D V C AlmeidaM S Miranda
Mar 1, 1996·Lipids·A M Papas
May 11, 2010·Reproduction, Fertility, and Development·Alvaro E Domínguez-RebolledoJ Julián Garde
Aug 2, 2000·The American Journal of Clinical Nutrition·P M Clarkson, H S Thompson

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