Abstract:Objective：This study investigated the protective effects of orientin and vitexin on hydrogen peroxide （H 2 O 2 ）-induced oxidative stress in human erythrocytes and structure-activity relationship.Methods：Oxidative stress model induced by H 2 O 2 was established in this study. The experiment was randomly divided into normal group，H 2 O 2 group （oxidative stress group），20 μg·mL -1 of VC group as a positive control，10，20 and 40 μg·mL -1 of Orientin groups and Vitexin groups，respectively. Erythrocyte suspension was incubated with different concentrations of orientin and vitexin，and then 1，1-diphenyl-2-picrylhydrazyl （DPPH） radical-scavenging ability，hemolysis rate，reactive oxygen species （ROS），antioxidant and ATP enzymes，malonaldehyde （MDA），methemoglobin （MetHb） and sulfhydryl （-SH） content were evaluated by different methods. Erythrocyte morphology was also observed with scanning electron microscope.Results：Erythrocytes pre-treated orientin or vitexin had certain DPPH-radical clearance ability，lowered hemolysis rates，reduced the content of ROS，MDA，MetHb protected antioxidative enzymes and ATPs activities and increased thiol group content in a dose-dependent manner （P<0.05）. Moreover，orientin and vitexin recovered cell surface morphogy. Comparative results showed the bio-activity of orientin was same as vitexin when the concentration was 40 μg·mL -1 for both，which was equivalent to VC at 20 μg·mL -1 . But orientin showed better biological activity than vitexin at the concentrations of 10 and 20 μg·mL -1 .Conclusion：Orientin and vitexin are able to protect human erythrocytes from oxidative stress through scavenging oxygen free radicals，inhibiting the perioxidation of lipids，protecting anti-oxidative and ATP enzymes activities and increasing-SH content. Moreover，the protective effects of orientin showed better biological activity than vitexin.

Key words:orientin,vitexin,human erythrocytes,anti-oxidative