Abstract: This study aimed to evaluate the antioxidant activity of Rosa laevigata Michx total flavonoids (RLTF) and to investigate the antioxidant effects of RLTF on human umbilical vascular endothelial cells (HUVEC) with oxidative damage induced by hydrogen peroxide (H₂O₂).The scavenging effects of RLTF on superoxide anion radical (O₂^-·) hydroxyl radical (·OH),and 1,1-diphenyl-2-picrylhydrazyl radical (DPPH·) were assayed by pyrogallol autoxidation,Fenton reaction and DPPH method,respectively.HUVECs were cultured and induced to oxidative injury by H₂O₂,cell nuclear morphological changes of HUVEC were observed by inverted fluorescent microscope after Hoechst 33258 staining,the cell vitality was measured by MTT assay.SOD,CAT and GSH-Px activities of HUVEC were assayed using spectrophotometry.The free radical scavenging experiments indicated that with the concentration increasing from 20 to 200 μg,the scavenging capacities of RLTF on ·OH and DPPH· radicals were increased gradually,while its O₂^-· clearance activity revealed the tendency of increasing firstly and decreasing afterwards.Hoechst 33258 staining observation showed that RLTF can effectively promote the antiapoptosis activity of HUVEC injured by H₂O₂ following pre-treated with RLTF for 24 h. The cell vitalities in different RLTF concentration groups were obviously raised compared with those of H₂O₂ groups (P＜0.01).The activities of SOD in 0.24 mg/mL and 0.48 mg/mL RLTF groups,and the activities of CAT and GSH-Px in all RLTF groups were significantly higher than those of H₂O₂ oxidative injury group (P＜0.01).The results showed that RLTF can protect HUVEC from oxidative damage by scavenging O₂^-·, ·OH and DPPH·,and by enhancing SOD,CAT and GSH-Px activities of HUVEC.

Key words: Rosa laevigata Michx, total flavonoids, free radicals, scavenging activity, antioxidative enzyme