Structure-activity relationship of bis-galloyl derivatives related to (-)-epigallocatechin gallate.

Green tea and (-)-epigallocatechin gallate (EGCG: one of main components of green tea) are well known to have preventive activities against human cancers. Previously, using a galloyl group as a core structure derived from EGCG, we developed alkyl gallate and gallamide derivatives, which showed strong antiproliferative activity towards human leukemia HL-60 cells by inducing apoptosis. Here, as a further structural development study, we planned to introduce an additional galloyl group into alkyl gallates and gallamides. According to this strategy, various bisgallate and bisgallamide derivatives were synthesized and tested for antiproliferative activity towards HL-60 cells. In gallamide derivatives having a short alkyl chain, the additional galloyl group enhanced the antiproliferative activity. In contrast, in the gallate derivatives, the additional galloyl group had no effect on the antiproliferative activity.