Background: Taxifolin is a flavanonol with efficacious cytoprotective properties, such as anti-inflammatory, antioxidant, anticancer, hepatoprotective, and nephroprotective effects. However, the potential protective effects of taxifolin against gentamicin-induced ototoxicity have not been confirmed. In this study, the possible mechanisms underlying the effects of taxifolin on gentamicininduced death of UB/OC-2 cochlear cells were investigated. Methods: Mouse cochlear UB/OC-2 cells with or without taxifolin pretreatment were exposed to gentamicin, and the effects on cytotoxicity, reactive oxygen species (ROS) production, mitochondrial permeability transition, and apoptotic marker expression were examined using biochemical techniques, flow cytometry, western blotting, and fluorescent staining. Results: Little or no apparent effect of taxifolin on cell viability was observed at concentrations less than 40 μM. Further investigations showed that gentamicin significantly inhibited cell viability in a concentration-dependent manner. Pretreatment with taxifolin attenuated gentamicin-induced lactate dehydrogenase release, as well as cellular cytotoxicity. In addition, taxifolin significantly prevented gentamicin-induced cell damage by decreasing ROS production, stabilizing mitochondrial membrane potential, and downregulating the mitochondrial pathway of apoptosis. Conclusion: In summary, pretreatment with taxifolin is effective for mitigating gentamicin-induced apoptotic cell death mediated by the mitochondrial pathway. Our data suggest that taxifolin provides a new approach to combat gentamicin-induced ototoxicity.

Gentamicin is an important aminoglycoside antibiotic used in the treatment of gram-negative bacterial infections, but nephrotoxicity and ototoxicity reduce its utility. The autophagy pathway is involved in damage of auditory hair cells. With the aim of developing new strategies for attenuating gentamicin ototoxicity, the present study investigated the otoprotective mechanism of 2,3,4′,5-tetrahydroxystilbene-2-O-β-D-glucoside (THSG) in vitro using the mouse cochlear cell line UB/OC-2. MTT assay demonstrated that gentamicin reduced UB/OC-2 cell viability and western blotting showed that gentamicin upregulated autophagy-related proteins, such as Beclin, autophagy related 5 and LC3-II. THSG significantly attenuated gentamicin-induced cytotoxicity, clearly reduced LDH release observed by LDH assay and decreased the expression of autophagy-related proteins. Reverse-transcription-quantitative (RT-q) PCR and western blotting showed that THSG against gentamicin-induced autophagy via suppressing the expression of Sesn2, at both the mRNA and protein level and a possible involvement of AMP-activated protein kinase (AMPK)/mTOR signaling response. Collectively, the present study demonstrated that THSG decreased gentamicin-induced ototoxicity in UB/OC-2 cochlear cells via the autophagic signaling in regulating Sesn2/AMPK/mTOR pathway. These results suggested that THSG might be a new therapeutic agent with the potential to attenuate gentamicin ototoxicity.