Effects of Extracts from Rhus Verniciflua S. on Activity of Catalase and TPA Mediated-Apoptosis in Cultured Mouse Hepatocytes

The ethanol extract of Rhus verniciflua S. was subsequently isolated and fractioned into two portions using H$_2$O and 99% ethanol as elution buffers through silica gel column chromatography. To study the antioxidative effect of Rhus verniciflua S. extracts, cultured hepatocytes were exposed to hydroxyl radical generated by 20 mU ml$^{-1}$ glucose oxidase for 4 h in the presence or absence of water or ethanol eluted extracts. Addition of 100 ${\mu}$g ml$^{-1}$ water extract to the culture medium protected from hydroxyl radical-mediated cytotoxicity of hepatocytes almost equivalently to the control. When the hepatocytes after culture for 24 h were incubated with 100 ${\mu}$g ml$^{-1}$ water or ethanol extract without glucose oxidase for 4 h, activity of catalase was increased by 1.40- and 1.31-fold, compared to the control, whereas with the commercial catalase (100 units ml$^{-1}$) was 1.64-fold. These results show that in vitro both extracts has a potential reducing cytotoxicity effect on hydroxyl radical and enhancing activities of the cellassociated catalase in cultured hepatocytes. Apoptosis induced by 12-O-tetradecanoylphorbol 13-acetate (TPA, 100 nM) in mouse hepatocytes were blocked by the addition of 100 ${\mu}$g ml$^{-1}$ of water or ethanol extract. In the biological effects of two extracts, water extract was more effective than that of ethanol extract.