The protective role of gallic acid esters in bacterial cytotoxicity and SOS responses induced by hydrogen peroxide

Abstract The effects of gallic acid and its esters on H 2 O 2 -induced cytotoxicity, mutagenicity and SOS response were investigated in bacterial assay systems, i.e., the Ames test with Salmonella typhimurium TA104 and the SOS chromotest with E. coli PQ37. In the Ames test, gallic acid esters showed protective effects against H 2 O 2 -induced cytotoxicity and no effects on the number of revertant colonies. In the SOS chromotest, gallic acid esters lowered the SOS induction factor raised by H 2 O 2 . Throughout the study, the effects of gallic acid itself were weak or negligible, and lauryl gallate was most effective among the three gallic acid esters. This structure-activity relationship indicates the similarity of the protective effects of gallic acid esters on the H 2 O 2 -induced damages to both bacterial and mammalian cells.