[Effects of daurisoline and its three optical isomers on ischemic injury in cultured pheochromocytoma (PC12) cells].

In this study, the protective effects of (-)-R.R-daurisoline and its three optical isomers on ischemic injury in cultured PC12 cells induced by treating cells with NaCN in glucose-free medium were investigated. Cell viability was measured using MTT assay. The results indicated that these compounds, especially (-)-S.R and (+)-R.S isomers were found substantially to attenuate ischemic injury in PC12 cells in a dose-dependent manner. The IC50 values of (-)-R.R, (-)-S.R, (+)-R.S and (+)-S.S isomers were shown to be 18.6 x 10(-6), 2.4 x 10(-6), 5.9 x 10(-6) and 90 x 10(-6) mol.L-1, respectively. Intracellular free Ca2+ concentration in PC12 cells was measured using AR-CM-MIC cation measurement system with Fura-2/AM as Ca2+ fluorescent indicator. (-)-R.R-daurisoline and its three optical isomers: (-)-S.R, (+)-R.S and (-)-S.S were found to markedly inhibit the increase of cytosolic free Ca2+ concentration induced by NaCN (20 mmol.L-1) in a dose-dependent manner. Their IC50 were found to be 3.55 x 10(-6), 0.59 x 10(-6), 1.29 x 10(-6) and 24.3 x 10(-6) mol.L-1 respectively. It is suggested that the cytoprotective effects of daurisoline and its isomers were mediated by blocking Ca2+ influx into cells.