Three new furostanol saponins from the bulbs of Ipheion uniflorum.

Phytochemical screening of the bulbs of Ipheion uniflorum (Liliaceae) has led to the isolation of three new furostanol saponins (2-4) along with a known phytoecdysteroid, ecdysterone (1). The structures of the new compounds were determined by two-dimensional NMR techniques, 1H-1H correlation spectroscopy (COSY), homonuclear Hartmann-Hahn (HOHAHA), phase-sensitive nuclear Overhauser effect spectroscopy (NOESY), heteronuclear multiple quantum coherence (HMQC) and heteronuclear multiple-bond correlation (HMBC) spectra, and hydrolysis to be 3 beta-hydroxy-22 alpha-methoxy-26-O-beta-D- glucopyranosyloxy-5 alpha-furost-25(27)-en-2-one 3-O-[O-alpha-L-rhamnopyranosyl-(1-->2)-O-[O-alpha-L-arabinopyranosyl+ ++- (1-->2)-O-[beta-D-xylopyranosyl-(1-->3)]-beta-D-glucopyranosyl-(1-->4)]- beta-D-galactopyranoside) (2) and its 25(27)-dihydro derivatives (3: 25S; 4: 25R). The inhibitory activity exhibited by compounds 1-4 and the corresponding spirostanol saponins (2a and 3a) of 2 and 3 on cAMP phosphodiesterase was assayed as a primary screening test to identify new compounds with medicinal potential.