In vitro protective effects of Hoveniae Semen cum Fructus extracts against oxidative stress

Abstract

We evaluated the in vitro cytoprotective effects of Hoveniae Semen cum Fructus (HSCF) extracts against oxidative stress-mediated cell damage using HepG2 cells. Cytotoxic effects of HSCF extracts were observed in HepG2 cells, and the 50% inhibitory concentration was determined. Cytoprotective effects of sublethal doses of HSCF extracts were evaluated using a tert-butyl hydroperoxide (tBHP)-induced cellular damage model. We also assessed whether NFE2-related factor-2 (Nrf2) was transactivated by HSCF extracts. The antioxidant capacity of HSCF extracts was evaluated with superoxide dismutase (SOD) and catalase (CAT) activities and the expression of the antioxidant genes glutamate cysteine ligase catalytic subunit (GCLC), hemeoxygenase-1 (HO1), and NAD (P)H dehydrogenase quinone 1 (NQO1). HSCF extracts up to 1,000 μg/mL showed no cytotoxic effect in HepG2 cells. Indeed, 300 and 1,000 μg/mL of HSCF extracts significantly protected HepG2 cells from oxidative stress-mediated cell death by tBHP. As a molecular mechanism, HSCF extracts at 1,000 μg/mL significantly increased Nrf2 transactivation and induced expression of its target genes (GCLC, HO1, NQO1). Furthermore, 1,000 μg/mL of HSCF extracts enhanced SOD activity. Although treatment with 300 and 1,000 μg/mL of HSCF extracts tended to slightly increase CAT activity, the increases were not statistically significant. These findings provide direct evident that HSCF extracts have favorable hepatoprotective effects against oxidative stress through Nrf2-mediated antioxidant gene induction.