Rhus verniciflua stokes extract: Radical scavenging activities and protective effects on H₂O₂-induced cytotoxicity in macrophage RAW 264.7 cell lines

The goal of this study was to determine the effects of Rhus verniciflua stokes (RVS) on the radical scavenging activities and H₂O ₂-induced cytotoxicity in macrophage 264.7 cells. An 80% ethanol extract of RVS was purified by ion exchange chromatography (IEC). Purified RVS extract contained a high amount of phenolics (55.5 g/100 g of extract) and flavonoids (5.9 g/100 g of extract) and its antioxidant activities, such as DPPH, superoxide anion and hydroxyl radical scavenging activities, was higher than the unpurified RVS extract. Purified RVS extract significantly reduced intracellular ROS formation caused by H₂O₂. Purified RVS extract also prevented the cell death of macrophage RAW 264.7 cells induced by H₂O₂. Interestingly, co-treated purified RVS extract effectively reduced thiobarbituric acid reactive substance (TBARS) formation, and attenuated catalase depletion at concentration of 100 μg/ml (p<0.05). Study using PDA-HPLC analyses have found that the purified RVS extract contains six major low molecular compounds as p-coumaric acid, fustin, kaempferol-3-O-glucoside, sulfuretin, butein and kaempferol. These results indicate that purified RVS extract, tested in this study, could contribute to the antioxidant activities and inhibition of intracellular ROS level.