Theaflavin-3'-gallate, a black tea theaflavin monomer, is regarded as the biologically important active component of black tea and provides health benefits. Theaflavin-3'-gallate acts as prooxidants and induces oxidative stress in the carcinoma cells. Theaflavin-3'-gallate reacts directly with reduced glutathione (GSH) in a time- and concentration-dependent manner^[1].