Anti-genotoxic effects of tea catechins against reactive oxygen species in human lymphoblastoid cells.

Using the cytokinesis-block micronucleus assay in WIL2-NS cells, we investigated the effects of six tea constituents, (-)-epigallocatechin-3-O-gallate (EGCg), (-)-epicatechin-3-O-gallate (ECg), (-)-epigallocatechin (EGC), (-)-epicatechin (EC), (+)-catechin (+C) and gallic acid (GA), on chromosomal damage in two ways; induction by each component on its own and prevention against treatment of reactive oxygen species (ROS). None of the tea constituents induced chromosomal damage at <10 microM. On the other hand, EGCg, EGC, ECg, +C and GA prevented H(2)O(2)-induced chromosomal damage in a dose-dependent manner with a significant effect detected at 1 microM. Chromosomal damage induced by tert-butylhydroperoxide was apparently prevented by EGCg and ECg at 0.3 microM, but not by EGC and GA even at 10 microM, suggesting that the galloyl group linked to flavan-3-ol is needed for the observed protective effect. These results suggest that physiological concentration of tea constituents are not genotoxic but rather anti-genotoxic against ROS, although their preventive effects are slightly different depending on their chemical structure.