Green rooibos extract attenuates high glucose induced oxidative stress in a human derived (HepG2) liver cell line

Abstract

The exposure of hepatocytes to high concentrations of glucose results in a glucotoxic environment and ensuing hepatocellular injury, often due to oxidative stress. The popularly consumed herbal teaR, ooibos (Aspalathus linearis), demonstrates pleiotropic pharmacological and antioxidant activities. Our study investigated the molecular events regulating the antioxidant effects of aR ooibos ethanolic extract R( EE) in a glucotoxic HepG2 liver cell model.I t is hypothesized thatR EE enhances antioxidant enzyme profiles of HepG2 cells exposed to high glucose to attenuate glucotoxic damage. Glucotoxicity was induced by treating the cells with 25 mM glucose. For this study, colorimetric, luminometric and western blot analyses were used to determine the potential of theR EE to reduce biomarkers associated with oxidative damage and its potential to enhance the intracellular antioxidant defense system. TheR EE was found to be hepatoprotective as evidenced by reduced levels of oxidative damage biomarkers (MDA and protein carbonylation) and enhanced antioxidant capacity under glucotoxic conditions as evidenced by elevated GSH (reduced form). We also observed decreased intracellular hydrogen peroxide levels and caspase activity in theR EE treated cells and further showed that theR EE enhanced SOD2C, AT, and GPxl protein expression. These effects were dependent on the transcriptional activity oNf RF2. Collectively, our results show that theR EE enhances the cellular antioxidant defense capacity and may provide a relevant supportive therapeutic option for treating diabetic complications associated with oxidative stress.