Structure-activity relationship of gallic acid from Paeonia lactiflora and its synthetic analogs against human breast cancer cells

Abstract

High-performance liquid chromatography analysis of the ethyl acetate fraction of Paeonia lactiflora roots led to the detection of five compounds: gallic acid (GA) (1), methyl gallate (2), albiflorin (4), paeoniflorin (5), and pentagalloylglucose (6). Among them, pentagalloylglucose (6) showed cytotoxicity against human breast cancer cells MCF-7 and MDA-MB-231 in vitro with IC50 values of 20.1 and 14.4 mu M, respectively. Through the structure-activity relationship of GA, which is an important backbone of pentagalloylglucose, we found that its three hydroxy groups were important for its cytotoxicity, and that the 3-O-methylgallic acid structure was only effective against a triple-negative breast cancer cell line. Furthermore, drug efficacy was confirmed by increasing its lipid affinity through the synthesis of various ester derivatives of gallic acid.