Detoxifying effect of fermented black ginseng on H₂O₂-induced oxidative stress in HepG2 cells

Fermented black ginseng (FBG) is prepared by repeated steaming and drying processes with fresh ginseng followed by fermentation with Saccharomyces cerevisiae. It has recently been shown to have several bioactivities. FBG contains crude saponin (1,440 μg/ml), ginsenoside Rg2 (2.86 μg/ml), ginsenoside Rg3 (24.52 μg/ml), ginsenoside Rh1 (12.64 μg/ml), ginsenoside Rh2 (0.63 μg/ml) and ginsenoside Rf (1.32 μg/ml). The present study investigated the antioxidant defense properties of FBG against hydrogen peroxide (H₂O₂)-mediated oxidative stress in HepG2 human hepatocellular carcinoma cells. The increased production of reactive oxygen species (ROS) induced by H₂O₂ was attenuated in a dose-dependent manner when the cells were pre-treated with FBG (10-50 μg/ml). FBG induced both the expression and activity of antioxidant enzymes, such as superoxide dismutase, catalase and glutathione peroxidase in the H₂O₂-treated HepG2 cells. The inhibitory effects of FBG on the phosphorylation of upstream mitogen-activated protein kinases (MAPKs), such as c-Jun N-terminal kinase, extracellular signal-regulated kinase and p38 were also observed. Overall, our results demonstrate that FBG protects HepG2 cells from oxidative stress through the induction of antioxidant enzyme activity and the inhibition of MAPK pathways.