Neuroprotective Effect of Baicalein on Hydrogen Peroxide-Mediated Oxidative Stress and Mitochondrial Dysfunction in PC12 Cells

Oxidative stress plays an important role in many neurodegenerative disorders. In this study, the effect of baicalein, a natural flavonoid isolated from the root of Scutellaria baicalensis G., on hydrogen peroxide (H₂O₂)-induced cytotoxicity in PC12 cells were investigated. Exposure of PC12 cells to 0.15 mM H₂O₂ for 20 min induced a significant decrease in cell viability accompanied by increased oxidative stress, mitochondrial dysfunction, downregulation of Bcl-2, upregulation of Bax, and cell apoptosis. Pretreatment of PC12 cells with baicalein inhibited H₂O₂-induced cell viability loss, intracellular reactive oxygen species generation, and lipid peroxidation in a dose-dependent manner. Meanwhile, baicalein potentially inhibited H₂O₂-induced cell apoptosis characterized with the DNA fragment. And the mitochondrial pathway involving the mitochondrial dysfunction associated with cell apoptosis including membrane potential loss, the release of cytochrome c, the downregulation of Bcl-2, upregulation of Bax induced by H₂O₂ were also abrogated in the presence of baicalein. Taken together, these results suggest that baicalein can block H₂O₂-induced apoptosis by prevention of oxidative stress as well as regulation of Bcl-2 family members and suppression of mitochondria dysfunction, which might be beneficial for the treatment of oxidative stress in aging and age-associated neurodegenerative diseases.