Abstract: AimTo observe the damages induced by hydrogen peroxide in cultured bovine cerebral microvascular endothelial cells (BCMEC) and evaluate the protective effects of hydroxyethylpuerarin on hydrogen peroxide-injured BCMEC. MethodsBCMEC were cultured and transferred into modified Eagle medium (MEM). The viability of cells was detected by MTT assay. Cell injury was determined by lactate dehydrogenase (LDH) activity in the extracellular medium. Flow cytometry was employed to observe the occurrence of apoptosis. Morphologic changes of cells were visualized under phase contrast and electron microscopes. ResultsHydrogen peroxide (200 μmol·L^-1 for 4 hours) inhibited the viability of cultured BCMEC and stimulated LDH release. Hydrogen peroxide (100 μmol·L^-1 for 4 hours) induced the occurrence of apoptosis. Hydroxyethylpuerarin was shown to increase the survival rate and decrease the activity of LDH of BCMEC damaged by hydrogen peroxide. Hydroxyethylpuerarin was also found to protect BCMEC against apoptosis induced by hydrogen peroxide. ConclusionHydrogen peroxide induces BCMEC injury either by apoptosis or through necrosis. Hydroxyethylpuerarin protects BCMEC against hydrogen peroxide-induced injury in a concentration-dependent manner. Its antioxidant effects might be involved as the mechanism protection.