Green tea from Camellia sinensis is known to contain catechins, dietary polyphenolic compounds associated with a wide variety of beneficial health effects. The widely renowned biological actions of catechins are their antioxidant and free radical scavenging properties. However catechins are also reported to induce oxidative damage through the generation of reactive oxygen species. Among the bioactive chemicals in green tea leaves (-)-epigallocatechin gallate (EGCG) is the most abundant and active. In the present study, the antioxidant capacity of EGCG was determined by the trolox equivalent antioxidant capacity assay and the effect of EGCG on DNA damage induced by H2O2 in human lymphocytes were investigated by the standard comet assay and the formamidopyrimidine-DNAglycoslase (Fpg) modified comet assay. Our results showed that above the concentrations of 0.01μM EGCG showed significant antioxidant capacity. At all the concentrations studied above 5 μM of EGCG alone significant DNA damage was observed. However, within the concentrations of 0.01-10 μM EGCG significantly reduced oxidative DNA damage induced by H2O2. At the concentration of 5μM EGCG induced Fpg sensitive sites indicating the increased oxidized purine base levels.
Keywords: (-)-Epigallocatechin gallate (EGCG), Hydrogen peroxide, Trolox equivalent antioxidant capacity (TEAC) assay, Comet assay, Formamidopyrimidine-DNA-glycoslase (fpg)