Steroidal saponins from Smilax riparia and S. china.

Two new neotigogenin glycosides were isolated from the rhizomes and roots of Smilax riparia and a new isonarthogenin glycoside from those of S. china. The structures were elucidated by a combination of spectroscopic analysis and hydrolysis followed by spectral and chromatographic analysis. Several known saponins were also isolated and identified. The inhibitory activity of the saponins on cAMP phosphodiesterase was examined.