Novel Steroidal Glycosides from the Whole Plants of Helleborus foetidus

Phytochemical analysis of the whole Helleborus foetidus plants identified 28 steroidal glycosides (1-28), including 20 novel spirostanol glycosides (1-20) and a novel furostanol glycoside (21). The structures of the newly identified compounds were elucidated by two-dimensional NMR spectroscopy and hydrolytic cleavage. Compounds 12, 13, and 15 were determined to be spirostanol trisdesmosides bearing sugar moieties at the C-1, -21, and -24 hydroxy groups of the aglycone unit. The isolated compounds were subsequently evaluated for cytotoxic activity against HL -60 human promyelocytic leukemia cells and A549 human lung carcinoma cells. In particular, 7 showed cytotoxic activity against the HL -60 and A549 cells, with IC50 values of 5.9 and 6.6pM, respectively, whereas 19 was selectively cytotoxic to A549 cells with an IC50 value of 5.5pM.