[Protective effect of Polygonum orientale flower extract on H₂O₂-induced oxidative damage of HUVEC cells].

To investigate the protective effects and mechanism of Polygonum orientale flower extract on H₂O₂-induced oxidative damage of human umbilical vein endothelial cells (HUVEC), H₂O₂ was used to induce the oxidativestress damage on HUVEC cells and efforts were made to screen the low, medium and high drug concentrations of P.orientale flower extract. Cell viability was detected by the MTS assay. The content of lactate dehydrogenase (LDH) and malondialdehyde (MDA), and the activities of superoxidedimutase (SOD) and catalase (CAT) were detected by biochemical kits. The mRNA and protein levels of Bax, Bcl-2 were detected respectively by quantitative real time polymerase chain reaction (qRT-PCR) and Western blot. The protein level of cleaved caspase-3 was detected by Western blot. According to the results, the viability of HUVEC cells was reduced to around 55% after being treated with 120 μmol·L⁻¹ H₂O₂ for 0.5 h. Treatment of H₂O₂ also could increase LDH leakage rate and MDA content and attenuate the activities of SOD and CAT, up-regulate the expression level of Bax and cleaved caspase-3, and down-regulate the expression level of Bcl-2. As compared with H₂O₂ model group, P.orientale flower extract of 50-200 mg·L⁻¹ could increase the viability of HUVEC cells, reduce LDH release and MDA content, enhance the activities of SOD and CAT, down-regulate pro-apoptotic protein cleaved caspase-3 and Bax, and up-regulate apoptosis inhibitory protein Bcl-2. In summary, P.orientale flower extract showed a protective effect on H₂O₂-induced HUVEC cells injury, which may result from enhancing the cell capability of clearing the oxygen free radial, decreasing the production of lipid peroxidation and inhibiting apoptosis.