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 S (1), gypenoside S (2), gypenoside S (3) and gypenoside S (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 IC values of more than 100 μM 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 μM from 66%, while as vitamin C to 67%. Compound 3 and 4 recovered more than 79% at 100 μM. 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 neuroprotecitve effect.