Abstract:

The antioxidant activities of green tea polyphenols (GTPs or TPs) and theaflavins (TFs) of varied purities were
investigated by measuring the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability and protective activity
against oxidative damage in yeast cells. Both TPs and TFs were able to scavenge DPPH radical. Results of protection against
oxidative damage showed that the survival rate of yeast cells was increased significantly by the addition of either TPs or
TFs, and their protective effects were positively correlated with their doses. It was found that 98% TPs showed the strongest
scavenging ability on DPPH radicals while 60% TFs showed comparable protective effect on yeast injured by H2O2 cells
to that of 90% TPs. Moreover, 60% TFs showed the strongest protect effect on UV damaged yeast cells. Thus, it could be
concluded that TPs and TFs possess in vitro and intracellular antioxidant activity, and there existed differences between the
antioxidant activities by varied assay methods.

Key words: tea polyphenols, theaflavins, antioxidant, 1,1-diphenyl-2-picrylhydrazyl (DPPH), yeast