2,3,4′,5-Tetrahydroxystilbene-2-O-β-D-Glucoside (THSG) Activates the Nrf2 Antioxidant Pathway and Attenuates Oxidative Stress-Induced Cell Death in Mouse Cochlear UB/OC-2 Cells

Oxidative stress plays a critical role in the pathogenesis of hearing loss, and 2,3,4′,5-tetrahydroxystilbene-2-O-β-D-glucoside (THSG) exerts antioxidant effects by inhibiting reactive oxygen species (ROS) generation. With the aim of developing new therapeutic strategies for oxidative stress, this study investigated the protective mechanism of THSG in vitro using a normal mouse cochlear cell line (UB/OC-2). The THSG and ascorbic acid have similar free radical scavenger capacities. H(2)O(2), but not THSG, reduced the UB/OC-2 cell viability. Moreover, H(2)O(2) might induce apoptosis and autophagy by inducing morphological changes, as visualized by microscopy. As evidenced by Western blot analysis and monodansylcadaverine (MDC) staining, THSG might decrease H(2)O(2)-induced autophagy. According to a Western blotting analysis and Annexin V/PI and JC-1 staining, THSG might protect cells from H(2)O(2)-induced apoptosis and stabilize the mitochondrial membrane potential. Furthermore, THSG enhanced the translocation of nucleus factor erythroid 2-related factor 2 (Nrf2) into the nucleus and increased the mRNA and protein expression of antioxidant/detoxifying enzymes under H(2)O(2)-induced oxidative stress conditions. Collectively, our findings demonstrate that THSG, as a scavenging agent, can directly attenuate free radicals and upregulate antioxidant/detoxifying enzymes to protect against oxidative damage and show that THSG protects UB/OC-2 cells from H(2)O(2)-induced autophagy and apoptosis in vitro.