Abstract

Parkia speciosa, a plant that grows abundantly in Southeast Asia region, has been reported to exhibit antioxidant property. This study aimed to investigate the mechanism of antioxidant effects of empty pod extract of Parkia speciosa on hydrogen peroxide-induced oxidative stress in H9c2 cardiomyocytes. There were 4 groups of cardiomyocytes, the negative control, hydrogen peroxide, extract of Parkia speciosa+hydrogen peroxide and quercetin+hydrogen peroxide. Cardiomyocytes of groups 3 and 4 were preincubated for 1 h with 500 µg/ml of the ethyl acetate fraction of the Parkia speciosa extract or 1000 µM quercetin prior to exposure to 500 μM hydrogen peroxide for 1 h. Hydrogen peroxide significantly increased the protein expression of NADPH oxidase 4, superoxide dismutase 1 and p38 mitogen-activated protein kinase, in comparison to the negative control. NADPH oxidase 4 and superoxide dismutase 1 activities as well as reactive oxygen species level were also elevated. These elevations were significantly decreased in the pretreated groups. The Parkia speciosa extract group had comparable effects to that of quercetin. Parkia speciosa extract showed antioxidant property against hydrogen peroxide-induced oxidative stress in H9c2 cardiomyocytes by regulating mitogen-activated protein kinase and NADPH oxidase 4 signaling pathways.