Triterpene saponins with α-glucosidase inhibition and cytotoxic activity from the leaves of Schefflera sessiliflora

From the leaves of Schefflera sessiliflora De P. V., two new triterpene saponins including one oleanane-type saponin, named scheffleraside C (1) and one lupane-type saponin scheffleraside D (2), together with six known triterpene saponins (3-8), were isolated by various chromatography methods. Among them, 3 was found for the first time from natural sources, while 6-8 were isolated for the first time from the genus Schefflera. Their structures were elucidated by IR, UV, HR-ESI-MS, NMR 1D and 2D experiments, and comparison of their NMR data with previously reported data. Their a-glucosidase inhibition and cytotoxic activity against MCF-7 human breast cancer cell lines were evaluated. The isolates (1, 3-5, 8) showed stronger a-glucosidase inhibitory activity (I (50) = 5.99-76.58 mu M) than the standard drug acarbose (IC50 = 214.50 mu M). At the concentration of 100 mu g/ml, the isolates (1, 2) showed appreciable cytotoxic activity (67.92, 63.83%, respectively).