Polyphyllosides A-F, six new spirostanol saponins from the stems and leaves of Paris polyphylla var. chinensis.

Abstract

The first phytochemical investigation on the steroidal saponins from the stems and leaves of Paris polyohylla var. chinensis led to the discovery and characterization of six new spirostanol saponins, named polyphyllosides A-F (1-6), along with four known analogues (7-10). Their structures were unambiguously established via extensive spectroscopic data and chemical methods. Both polyphyllosides A and B had a rare aglycone with a C-4/C-5 double bond and a C-6 hydroxy group moiety, whereas polyphylloside C represents the first saponin with a unique aglycone sharing a C-6/C-7 double bond and a C-5 hydroxy group unit. All these saponins were evaluated for their cytotoxic activities against five selected human cancer cell lines. Among these, the known saponins 7 and 10 exhibited significant cytotoxic effects on HeLa cells with IC50 values of 4.16 and 4.45μM, respectively. The structure-activity relationships (SAR) of these isolates were also discussed. Flow cytometric analysis indicated that 7 could induce MDA-MB-231 cell death in a concentration-dependent manner. Saponin 7 was proved to affect the cell cycle distribution and induced G2/M phase arrest in MDA-MB-231 cells.