Structure Elucidation of 16 Undescribed Steroidal Glycosides from the Underground Parts of and Apoptosis-Inducing Activity in Small-Cell Lung Cancer Cell.

To explore new candidates for anticancer agents from natural products, the underground parts of , commonly used as an ornamental plant, were investigated phytochemically. As a result, 16 undescribed steroidal glycosides (-) were obtained, and their structures were determined mainly by NMR spectroscopic analysis and chemical transformations. The cytotoxic activities of the isolated compounds (-) against SBC-3 human small-cell lung cancer cells, A549 human adenocarcinoma cells, and HL-60 human promyelocytic leukemia cells were evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2-tetrazolium bromide (MTT) assay. Compound , a bisdesmosidic furostanol glycoside, and , a bisdesmosidic spirostanol glycoside, were cytotoxic to all three cell lines with IC values ranging from 1.2 to 13 μM. As exhibited the most potent cytotoxicity against SBC-3 cells among the isolated compounds, its apoptosis-inducing activity toward SBC-3 cells was examined. Compound arrested SBC-3 cells at the G/M phase of the cell cycle and effectively induced apoptosis via an intrinsic pathway accompanied by the dissipation of membrane potential and morphological changes in mitochondria.