Apoptotic Effect of Pinosylvin at a High Concentration Regulated by c-Jun N-Terminal Kinase in Bovine Aortic Endothelial Cells

Pinosylvin is a stilbenoid found in the Pinus species. Pinosylvin at ~pM to ~nM concentrations in-duces cell proliferation, cell migration and anti-inflammatory activity in endothelial cells. However, it was recently reported that pinosylvin at high concentrations (50 to 100 µM) induces cell death in bo-vine aortic endothelial cells. In this study, we conducted a series of experiments to discover how pino-sylvin at a high concentration (50 µM) induces endothelial cell death. Pinosylvin at the high concen-tration was shown to induce endothelial cell apoptosis through enhancing caspase-3 activity, flip-flop of phosphatidyl serine, and nuclear fragmentation. We found that pinosylvin at the high concentration additively increased caspase-3 activity enhanced by serum-starvation or treatment with 100 µM etoposide. We also determined that pinosylvin at the high concentration promoted activations of c-Jun N-terminal kinase (JNK) and endothelial nitric oxide synthetase (eNOS). We further ran a series of experiments to find out which signaling molecule plays a critical role in the pinosylvin-induced apoptosis. We finally found that SP-600125, a JNK inhibitor, had an inhibitory effect on the pino-sylvin-induced endothelial cell death, but L-NAME, an eNOS inhibitor, had no effect. These data in-dicate that JNK is involved in the pinosylvin-induced apoptosis. Collectively, pinosylvin at high doses induces cell apoptosis via JNK activation.