Abstract: To investigate the protective effect of Polygonum orientale Flower Ethanol Extracton H₂O₂-induced Oxidative damage in H9c2 Cells.200 μmol/L H₂O₂ was used to induce the oxidativestress damage model in H9c2 cells for 0.5 h in vitro.The H9c2 cells were randomly divided into control group,the model group（200 μmol/L H₂O₂）and the Polygonum orientale  Flower ethanol Extract different groups（20、40、80 μg/mL）.Cellviability was determined by MTS assay.Thecontentoflactate dehydrogenase (LDH),malondialdehyde (MDA) and the activities of superoxidedimutase (SOD) and catalase (CAT) were detected by biochemical kits.The protein levels of caspase-3,Bax,Bcl-2,p-AKT and AKT were detected by Western blot．Compared with model group, Polygonum orientale   Flower Ethanol Extract pre-treatment improved cell viabilityand the activities of SOD and CAT in a dose-dependent manner,and attenuated leakage of LDH and content of MDA. Polygonum orientale  Flower Ethanol Extract depressed myocardial apoptosis by down-regulating pro-apoptotic protein cleavedcaspase-3 and Bax,up-regulating apoptosis inhibitory protein Bcl-2 and increasing the protein level of p-AKT.LY294002 could offsets such an effect of  Polygonum orientale  Flower Ethanol Extract．In summary, Polygonum orientale  Flower Ethanol Extract showed a protective effect on H₂O₂ -induced injury in H9c2 cells.This protection may result from inhibiting myocardial oxidative apoptosis,balancing the oxidative stress and maybe related with the PI3K/Akt signaling pathway.

Key words: Polygonum orientale Flower Ethanol Extract, oxidative stress injury, H9c2 cells, PI3K/Akt