STEROIDAL SAPONINS FROM THE TUBERS OF DICHELOSTEMMA-MULTIFLORUM AND THEIR INHIBITORY ACTIVITY ON CYCLIC-AMP PHOSPHODIESTERASE

Phytochemical examination of the tubers of Dichelostemma multiflorum l ed to the isolation of three new steroidal saponins together with two known saponins. The structures of the new compounds were determined by spectral data and a few chemical transformations to be (25R)-S alpha- spirostane-1 beta,3 beta-diol (brisbagenin) 1-O-{O-alpha-L-rhamnopyran osyl-(1 --> 3)-4-O-acetyl-alpha-L-arabinopyranoside}, brisbagenin 1-O- {O-alpha-L-rhamnopyranosyl-(1 --> 2)-O-[alpha-L-rhamnopyranosyl-(1 --> 3)]-4-O-acetyl-alpha-L-arabinopyranoside} and (22S,25S)-5 alpha-spiro stan-3 beta-ol 3-O-{O-beta-D-galactopyranosyl-(1 --> 2)-O-[beta-D-xylo pyranosyl-(1 --> 3)]-O-beta-D-glucopyranosyl-(1 --> 4)-beta-D-galactop yranoside}. The known compounds were identified as desglucolanatigonin II and gitonin, with certain amounts of the corresponding C-25S isome rs. Inhibitory activity of the isolated saponins and their derivatives on cAMP phosphodiesterase was evaluated to identify new compounds wit h medicinal potential.