Abstract: To study the characteristics of alcohol-induced oxidative damage in QZG cells and antioxidant activity of Rhodiola ethanol-extract. METHODS： The DPPH system and chemiluminescence system models for determination of ·OH and O2.- were established to assess the inhibitive rates of DPPH radicals and chemical luminescence intensity of ·OH and O2-. . The oxidative damage model induced by ethanol in QZG cells was set up to measure the protective activities of Rhodiola ethanol-extract. Ethanol-extract of Rhodiola was divided into 3 different concentrations (50，100，200 mg/L) for the prophylaxis group and treatment groups，positive control group (200 mmol/L ethanol intervention) and negative control group (without test substance). Prophylaxis QZG cells were pretreated with Rhodiola ethanol-extract for 12 h，then 200 mmol/L ethanol added for 6 h. Treatment group received 200 mmol/L ethanol and Rhodiola ethanol-extract for 6 h. We used MTT test and biochemical method for determining cell vitality， malondialdehyde (MDA) and reduced and oxidized glutathione (GSH，GSSG) and total mercaptoacetic (T-SH) content and catalase (CAT)，superoxide dismutase enzyme (SOD) activity，Western blot to detect protein expression of antioxidant enzymes HO-1 and NRF-2. RESULTS: In the DPPH system and the two chemiluminescence systems，Rhodiola ethanol-extract could significantly inhibit generation of free radicals. In the oxidative damage model induced by et hanol in QZG cells，Rhodiola extract could effectively protect cell injury induced by alcohol，and the treatment groups showed an evident dose-effect relationship. Ethanol-extract of Rhodiola intervention groups reduced the contents of MDA and GSSG compared with positive control group (P<0.05)，and increased the content of GSH and T-SH. The treatment groups also demonstrated high CAT and SOD activities. Western blot results showed that Rhodiola ethanol-extract could induce the protein expressions of antioxidant enzymes HO-1 and NRF-2. CONCLUSION：Ethanol-extract of Rhodiola could significantly inhibit generation of free radicals in three kinds of free radicals models in vitro，also effectively protected against ethanol-induced oxidative damage in QZG cells，may be through its antioxidant activity.

Key words: Rhodiola ethanol-extract, DPPH, chemiluminescence, alcohol, oxidative stress