Protective effects of four new saponins from Gynostemma pentaphyllum against hydrogen peroxide-induced neurotoxicity in SH-SY5Y cells

Gynostemma pentaphyllum has been used as a medicine-food homologious health product in China for a long time. This research aimed to isolate and identify its active compounds with protective effects against hydrogen peroxide induced SH-SY5Y cell death. Four new dammarane-type saponins were isolated from G. pentaphyllum using various chromatographic methods. They were identified as gypenoside Si (1), gypenoside S-3 (2), gypenoside S-2 (3) and gypenoside S-4 (4), respectively by HRESIMS and NMR spectra. Their cytotoxic activity was evaluated against three human cancer cell lines, A549 (lung), HepG2 (liver), SH-SY5Y (nerve), by MTT method. They showed low cytotoxicities with the IC50 values of more than 100 mu M on three cancer cell lines. However, they appeared protective effects against hydrogen peroxide induced SH-SY5Y cell death in a dose-dependent manner. They recovered cell viability more than 69% at the concentration of 20 mu M from 66%, while as vitamin C to 67%. Compound 3 and 4 recovered more than 79% at 100 mu M. The present study suggests that G. pentaphyllum has antioxidative potential and the saponins from G. pentaphyllum are considered as the active compounds with safe and neuropmtecitve effect.