Formation of reactive oxygen intermediates might be involved in the trypanocidal activity of gallic acid.

We investigated the mechanism of the trypanocidal activity of gallic acid (GA). GA-induced trypanocidal activity was significantly reduced by pretreatment with superoxide dismutase (SOD) and/or catalase. The ESR technique with 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as a spin trapping agent revealed that a DMPO-OH adduct was detected in culture medium containing GA. The intensity of ESR signals of the DMPO-OH adduct was increased in a time dependent manner. SOD also inhibited the formation of GA-induced DMPO-OH adducts. Furthermore, GA enhanced DNA single-strand breaks induced by Fenton reagent. These results suggest the possibility that GA acts as pro-oxidant for trypanocidal activity.