Protective Effect of Oak Extracts on Oxidative Stress Induced by Hydrogen Peroxide

This study was done to evaluate the antioxidant effect of oak hot water extracts on the oxidative stress induced by reactive oxygen species (ROS). The cytotoxicity of $H_2O_2$-induced oxidative stress was performed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay for the cell viability according to the dose-dependent treatment. Oak extracts demonstrated a dose-dependent ability to inhibit $H_2O_2$-induced apoptosis in cultured tenofibroblasts, as assessed by MTT assay and FACS analysis. $H_2O_2$ increased the phosphorylation of extracellular regulated kinase1/2 (ERK1/2) and of c-Jun N-terminal kinase (JNK) and the production of reactive oxygen species (ROS). In contrast, treatment with oak extracts was decreased this activation of ERK1/2 and JNK, as confirmed by western blot analysis, and reduced the production of ROS, as verified by fluorescent microscopic and flow cytometry (FACS) analyses. These findings suggest that oak extracts, by suppressing JNK, ERK1/2, and intracellular ROS production, have a concentration-dependent antiapoptotic effect on achilles tenofibroblasts exposed to an oxidative stressor, and may have therapeutic potential.