Protective effect of protocatechuic acid from Alpinia oxyphylla on hydrogen peroxide-induced oxidative PC12 cell death

The neuroprotective effects of protocatechuic acid (PCA), a phenolic compound isolated from the kernels of Alpinia oxyphylla, on hydrogen peroxide (H2O2)-induced apoptosis and oxidative stress in cultured PC12 cells were investigated. Exposure of PC12 cells to 0.4 mM H2O2 induced a leakage of lactate dehydrogenase (LDH) and decreased cell viability denoted by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. PCA increased PC12 cellular viability and markedly attenuated H2O2-induced apoptotic cell death in a dose-dependent manner. By flow cytometric analysis, PCA showed its significant effect on protecting PC12 cells against H2O2-induced apoptosis. In these cells, the levels of glutathione (GSH) and activity of catalase were augmented, while glutathione peroxidase activity remained unchanged. In addition, PCA also protected against cell damage induced by H2O2 and Fe2+, which generated hydroxyl radicals (˙OH) by the Fenton reaction. These results suggest that PCA may be a candidate chemical for the treatment of oxidative stress-induced neurodegenerative disease.