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Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY 14214
2To whom correspondence should be addressed. E-mail: smkuo{at}buffalo.edu.
The antioxidant activity of flavonoids in cell-free systems has been studied extensively. We compared flavonoids with different structural features on their abilities to protect live Caco-2 intestinal cells from lipid peroxidation due to hydrogen peroxide and Fe2+ treatment. Flavonoids with o-dihydroxyl or vicinal-trihydroxyl groups, including quercetin, myricetin (flavonol), luteolin (flavone) and (-)-epigallocatechin gallate (EGCG; flavanol), when co-incubated with a mixture of 30 µmol/L H2O2 and 30 µmol/L FeSO4, prevented the formation of malondialdehyde (MDA) at 1 or 10 µmol/L in at least one of two separate experiments. In experiments in which flavonoids were preincubated with cells but removed before the 30 µmol/L H2O2 and Fe2+ treatment, quercetin at 0.1 µmol/L, EGCG at 1 µmol/L and luteolin at 10 µmol/L exerted protective effects in at least one of two experiments. Kaempferol (flavonol) and the isoflavones, genistein and daidzein, did not prevent lipid peroxidation at 0.110 µmol/L in either co- or preincubation experiments. None of the flavonoids tested at 0.110 µmol/L increased H2O2 and Fe2+-induced lipid peroxidation after co- or preincubation. In summary, these observations support the importance of plant-based food items such as vegetables, fruits and teas in the diet.
KEY WORDS: flavonoids reactive oxygen species iron malondialdehyde Caco-2 cells
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