Tempeh extract reduces cellular ROS levels and upregulates the expression of antioxidant enzymes

Abstract

Tempeh is an Indonesian traditional food produced from soybeans through a mould fermentation involving Rhizopus oligosporus. It is rich in bioactive phytochemicals, including isoflavones that are known to exhibit antioxidant activities. This study aimed to investigate the ability of tempeh ethanol extract to reduce cellular reactive oxygen species (ROS) levels in HepG2 cells in vitro. Tempeh extract exhibited greater total phenolics, total flavonoids and free radical inhibition capacity than soybean extract. Both tempeh extract and soybean extract reduced the basal levels of cellular ROS in the cells, but tempeh extract induced higher expression of antioxidant enzymes [catalase, superoxide dismutase-2 (SOD2) and superoxide dismutase-3 (SOD3)] compared to soybean extract. This study provides novel evidence suggesting the ability of tempeh to tackle cellular oxidative stress by upregulating the expression of antioxidant enzymes. These findings would give an insight into the potential of tempeh to be developed as a functional food beneficial for human health.