Tempeh Extract Protects HepG2 Cells Against Oxidative Stress-Induced Cell Death

Tempeh is an Indonesian fermented traditional food made from soybeans inoculated with Rhizopus oryzae and/or Rhizopus oligosporus. It exerts antioxidant activities mainly due to the presence of bioactive compounds known as isoflavones. We previously observed that tempeh ethanol extract increased the basal expression of some cellular antioxidant enzymes including catalase and superoxide dismutases in HepG2 cells in vitro. In this study, we showed that pretreament with tempeh extract protected HepG2 cells from oxidative stress triggered by TBHP (tert-butyl hydroperoxide) by reducing cellular ROS (reactive oxygen species) generation, TBARS (thiobarbituric acid reactive species) levels, caspase-3 activity and eventually cell death. We hypothesize that the resistance of cells pretreated with tempeh extract towards the toxicity of TBHP was in part due to the upregulation of cellular antioxidant enzymes. Taken together, our findings highlight the antioxidative potentials of tempeh, particularly in an attempt to develop tempeh as a functional food offering health-related benefits to humans.