Protective Effects of Phillyrin on H sub(2)O sub(2)-induced Oxidative Stress and Apoptosis in PC12 Cells

Oxidative stress is a major component of harmful cascades activated in neurodegenerative disorders. We sought to elucidate possible effects of phillyrin, an active constituent isolated from the Chinese medicinal herb Forsythia suspense, on hydrogen peroxide (H sub(2)O sub(2))-induced cell death and determine the underlying molecular mechanisms in neuron-like PC12 cells. By MTT assay and lactate dehydrogenase (LDH) leakage assay, we found that phillyrin treatment effectively protected PC12 cells against H sub(2)O sub(2)-induced cell damage. H sub(2)O sub(2) exposure induced oxidative stress in PC12 cells, as revealed by enhanced oxidative stress and decreased activities of antioxidative enzymes, which were inhibited by phillyrin pretreatment. ROS activated mitochondria-dependent apoptosis. The anti-apoptotic effects of phillyrin were also confirmed by acridine orange/ethidium bromide (AO/EB) staining. Mitochondrial membrane potential decrease, cytochrome c release, caspases activation, activation of AIF and Endo G were observed in H sub(2)O sub(2)-treated cells by rhodamine 123 or western blot. Interestingly, phillyrin effectively suppressed these changes. Moreover, phillyrin could inhibit H sub(2)O sub(2)-induced up-regulation of Bax/Bcl-2 ratio. In conclusion, phillyrin effectively inhibited H sub(2)O sub(2)-induced oxidative stress and apoptosis in PC12 cells.