Abstract: To study the antioxidative activities of the ethanol extract of panax notoginseng (PNG) in several free radical models in vitro and in oxidative damage rat model in vivo. METHODS：The chemiluminescence systems models for determination of hydroxyl radical (·OH) and superoxide anion radical (O2-. )were built to observe the inhibitory rates of luminous intensity by different concentrations of PNG extract. The microsomal lipid peroxidation model stimulated by CHP，VC/Fe2+ and CC14/NADPH were established to observe the inhibition of MDA by different concentrations of PNG extract. The oxidative damage rat model was built by 60Co-γray to observe the inhibitory effect of PNG extract on the generation of MDA and GSSG， and the changes of CAT and SOD activities in livers. RESULTS： In the two chemiluminescence systems， the inhibitory rates of ·OH and O2-. by PNG extract were significantly higher than that in control group， with significant dose-effect relationship. The IC50 of O2-. and ·OH by ethanol extract of PNG were 1.25 mg/ml and 0.625 mg/ml， respectively. Compared with that in control group， the content of MDA in the three LPO models decreased significantly (P<0.05) at different concentrations，with a dose-effect relationship. After PNG oral administration， decrease of MDA was observed in rat livers. The activities of SOD and CAT were increased by ethanol extract，the content of GSSG was decreased by ethanol extract. CONCLUSION：In several in vitro and in vivo models described above， the ethanol extract of PNG demonstrated effective antioxidative effects and revealed a dose-effect relationship.

Key words: panax notoginseng, radiation, antioxidation activity, microsomal lipid peroxidation models, free radical