Bioactive spirostane glycosides from Tacca plantaginea.

Eight new spirostane glycosides, taccaosides E-L (2-7, 11, and 14), along with 7 known spirostane glycosides were isolated from the extract of the whole plants of Tacca plantaginea (Hance) Drenth. Their structures were established on the basis of physical data, spectroscopic analysis (MS, 1D and 2D NMR), and chemical methods. The cytotoxicities of the isolates were evaluated in vitro against two human cancer cell lines (HEK293 and HepG2). The results showed that compound 1 had the strongest cytotoxic activity with IC50 values of 1.7 μM and 1.2 μM against the two cancer cell lines, respectively. Furthermore, the spirostane glycosides with 17α-hydroxyl group at their aglycones (10, 12, and 15) were tested for the induced platelet aggregation activity.