Protective Role of Hinokitiol Against H2O2-Induced Injury in Human Corneal Epithelium.

Purpose: We recently found that hinokitiol has anti-inflammatory activity in human corneal epithelial (HCE) cells. Herein, we investigated the protective role of hinokitiol against H2O2-induced injury in HCE cells and the mechanisms that underlie its action.Methods: HCE cells were incubated with different concentrations of hinokitiol or dimethylsulfoxide (DMSO), which served as a vehicle control, before H2O2 stimulus. The cell viability was evaluated using a cell counting kit-8 (CCK-8) assay. TUNEL, phosphorylated histone H2A.X, cleaved caspase-3 expression analyses, and location of cytochrome c were conducted to detect cell injury and apoptosis. Reactive oxygen species (ROS), catalase (CAT), superoxide dismutase (SOD), methane dicarboxylic aldehyde (MDA), and total antioxidative capacity (T-AOC) were used to determine oxidative stress. Bcl-2 and Bax protein expressions were measured by western blotting.Results: Hinokitiol significantly improved the cell viability, decreased the apoptosis rate, inhibited DNA damage, and reduced cleaved caspase-3 expression and the leakage of cytochrome c from mimitochondrion to cytoplasm of HCE cells against the oxidative stress induced by H2O2. Generation of ROS and MDA and decreased activity of CAT, SOD, and T-AOC were also ameliorated by hinokitiol administration. Moreover, Bcl-2 expression was down-regulated while Bax was up-regulated by H2O2 stimulus, which were reversed by hinokitiol application.Conclusion: Hinokitiol protects HCE cells against H2O2-induced injury likely by its antioxidant activity and modulating the Bcl-2 signaling pathway.