Inhibitory activities of (-)-epigallocatechin-3-O-gallate against topoisomerases I and II

The substitution of gallic acid at the 3 position of (-)-epigallocatechin-3 -O-gallate (EGCG) increased the inhibition against topolsomerase I from cal f thymus gland and topoisomerase H from human placenta, and the substitutio n of a hydroxyl group at the 3 ' position increased the inhibition against the topoisomerase I. These results suggested that the 3 and 3 ' positions o f the EGCG molecule play important roles in the process of inhibition of to poisomerases I and II. EGCG showed strong inhibition against topoisomerases I from wheat germ, calf thymus gland and Vero cells, and showed weak or no inhibition against topoisomerases I from carcinoma cells such as A549, HeL a and COLO 201 cells. EGCG differentially inhibited the topoisomerases I fr om different sources.