Radical-scavenging abilities and antioxidant properties of theaflavins and their gallate esters in H2O2-mediated oxidative damage system in the HPF-1 cells

The antioxidant properties of theaflavins and their gallate esters, namely theaflavin (TF1), theaflavin-3(3′)-gallate (TF2) and theaflavin-3,3′-digallate (TF3) were investigated by comparing with epigallocatechin gallate (EGCG). The order of hydroxyl radicals-scavenging ability was TF3 > TF2 > TF1 > EGCG. The order of 2,2-diphenyl-1-picrylhydrazyl scavenging ability was TF3 > TF2 > EGCG > TF1. TF1, TF2, and TF3 showed more effective effects than EGCG in protection against H2O2-mediated damage in HPF-1 cells. TF2 was the most potent accelerant of HPF-1 cell proliferation. TF1, TF2 and TF3 suppressed the accumulation of intracellular reactive species in H2O2-mediated damage HPF-1 cells. Pre-treated for 2 h and eliminated from the cells, TF1 and TF3 still showed protective effects against H2O2-mediated damage in HPF-1 cells. This suggests that the protective effects of TF1 and TF3 on oxidative damage HPF-1 cells may be responsible for other mechanisms, rather than only scavenging the already formed reactive species. It remains to be determined whether TF1 and TF3 improved the normal HPF-1 cell resistive abilities toward radical-damage in pre-treatment. Further studies of the effects of theaflavins on some enzymes or signal transduction in the normal HPF-1 cells are underway.