protective effect of melissa officinalis extract against h2o2-induced oxidative stress in human vascular endothelial cells

melissa officinalis l. is a medicinal plant with a large variety of pharmacological effects and traditional applications. this study aimed to evaluate the protective and antioxidant activities of the extract of m. officinalis aerial parts on human umbilical vein endothelial cells (huvecs) under oxidative stress induced by h 2 o 2 . cells were incubated with h 2 o 2 (0.5 mm, 2 h) after pretreatment with m. officinalis extract (25-500 µg/ml). cell viability was evaluated by 3-(4, 5- dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (mtt) assay. the concentration of hydroperoxides and ferric reducing antioxidant power (frap) were measured in intra- and extra-cellular fluids. pretreatment of huvecs with m. officinalis extract at the concentrations of 100-500 µg/ml improved the cell viability after exposure to h 2 o 2 significantly. it also decreased hydroperoxides concentration and increased frap value in both intra- and extra-cellular fluids. the results revealed antioxidant and cytoprotective effects of m. officinalis against h 2 o 2 -induced oxidative stress in huvecs. due to the valuable antioxidant activity, this plant extract may have potential benefits for the prevention of cardiovascular diseases associated with oxidative stress.