There were small protective effects of vitamin C at low doses. Trolox quercetin: X OH, R OH, R H; apigenin: X H, R H, R H; kaempferol: X OH, R H, R H; luteolin: X H, R OH, R H; and myricetin: X OH, R OH, R OH.In the present study we showed that the comet assay can be used to give reproducible results in estimating the extent of oxidative DNA damage to human lymphocytes.It thus proved possible to rank the potency of the antioxidant agents tested with high condence.It was clear that vitamin C, well recognized as a dietary antioxidant, provides denite protection against oxidative DNA damage at normal human physiologic concentrations.The concentrations of vitamin C tested were chosen to span the normal plasma concentrations from to mmolL are found in leukocytes, including lymphocytes, which concentrate vitamin C to concentrations fold greater than those in plasma. Intracellular concentrations were not measured in the present study.Fruit and vegetables provide of total vitamin C intake and these foods are likely to contribute other antioxidants, including avonoids.Antioxidant activity of flavonoids against oxygen radicalgenerated oxidative DNA damage in human lymphocytes in the comet assay.FLAVONOIDS AND OXIDATIVE DNA DAMAGE of the avonoids tested than for vitamin C.These observational associations have suggested a causal relation mediated by dietary antioxidants limiting lipid peroxidation and DNA damage.Most analyses have sought mechanisms based on antioxidants routinely included in nutrient databases, and, on the basis of this type of research, intervention studies using vitamin C, vitamin E, and bcarotene have been mounted.The potential for error in this approach was shown by a study that showed no benet, indeed potential harm, from isolated bcarotene supplementation. The present study supports the possibility that other bioactive compounds such as avonoids, which are known to have appropriate actions, may be important factors for health that coexist with the more familiar antioxidant vitamins.Flavonoid analysis in human diets is now becoming possible and the factors that govern their concentrations in foods are becoming better understood.The importance of quercetin, one of the most widespread and also most potent antioxidant avonoids, is highlighted by the results of the present study.Quantitative analysis of flavonoids by reversedphase highperformance liquid chromatography.Dowlnoadedfromhttps: academi. coupco. mjacn a rti l ce bygueston Sepetmber A lthough repair rates were large for all species evaluated, they were apparently inadequate to prevent the transient accumulation of substantial CPD burdens.The concentration of stratospheric ozone has decreased sign ificantly during the past two decades, the result of cataly tic destruction of ozone mediated by the photodegradation products of anthropogen ic chlorof luorocarbons. This article must therefore be hereby marked adver tisement in accordancewith U.Nevertheless, the CPD burden resulting from sublethal doses of UVB may inhibit embr yon ic and lar val development and ultimately decrease survival, by slow ing transcription and mitosis and by imposing energetic costs associatedwith DNA repair. The impact of elevated UVB on marine ecosystems has been documented most extensively for the primaryproducers of polar latitudes. The two primaryrepair systems are photoenzymatic repair. Specimens included fish lar vae, fish eggs, chaetognaths, and annelids.