Antitumor principle constituents of Myrica rubra var. acuminata

Myrica rubra var. acuminata is a native shrub widely distributed and used as folk medicine in Taiwan for stomach disorders and diarrhea. Column chromatography combined with cytotoxic bioassay guided fractionation was performed to isolate the antitumor principles from fresh leaves of M. rubra var. acuminata. The 20% MeOH eluate fraction of M. rubra var. acuminata inhibited the viability of HeLa and P-388 cells in an in vitro assay and an in vivo P-388 tumor-bearing CDF₁ mouse model. The percent increase in life span (%ILS) of 20% MeOH eluate fraction was greater than 125%. (-)Epigallocatechin 3-O-gallate (1) and prodelphinidin A-2,3′- O-gallate (2) were isolated from D-20 as the antitumor principle components. Both compounds can inhibit the growth of HeLa cells, but 1 had lower cytotoxic effects in normal cervical fibroblasts than did 2. Moreover, pretreatment with a caspase-3 specific inhibitor prevented 1- and 2-induced poly(ADP-ribose) polymerase cleavage. In view of these results, we suggest that 1 and 2 can induce apoptosis in HeLa cells and that activation of caspase-3 may provide a mechanistic explanation for their cytotoxic effects. Therefore, we suggest that the 20% MeOH eluate fraction extract is good for health and that M. rubra var, acuminata is an economically valuable plant.