Empetrum nigrum var. japonicum Extract Suppresses γ-Ray Radiation-Induced Cell Damage via Inhibition of Oxidative Stress

The ethylacetate fraction of Empetrum nigrum var. japonicum (ENE) was shown to reduce intracellular reactive oxygen species (ROS) generated by gamma-radiation and activate antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT), and gluthathion peroxidase (GPx). ENE protected cells against radiation-induced cellular DNA damage, membrane lipid peroxidation, and protein modification, which are the main points of radiation-induced damage. In addition, ENE recovered cell viability by inhibiting apoptosis after cells were treated with radiation. ENE treatment also reduced gamma-radiation induced Bax, and caspase 9 and 3 expression in irradiated cells. However, irradiated cells with ENE recovered Bcl-2 expression, which was reduced by radiation. This anti-apoptotic effect of ENE was due to the inhibition of mitogen-activated protein kinase kinase-4 (MKK4/SEK1)-c-Jun NH2-terminal kinase (JNK) cascades induced by gamma-radiation. In summary, these results suggest that ENE protects cells against gamma-radiation-induced oxidative stress via the reduction of ROS and attenuation of apoptosis.