A new bioactive steroidal saponin from Agave shrevei.

A new steroidal saponin was isolated from the leaves of Agave shrevei Gentry. Its structure was established as 26-(beta-D-glucopyranosyloxy)-22-methoxy-3-(O-beta-D-glucopyranosyl-(1-->2)O-[O-beta-D-glucopyranosyl-(1-->4)-O-[O-beta-D-glucopyranosyl-(1-->6)]-O-beta-D-glucopyranosyl(1-->4)-beta-D-galactopyranosyl]oxy)-(3beta,5alpha,25R)-furostane. The structural identification was performed using detailed analyses of 1H and 13C NMR spectra including 2D NMR spectroscopic techniques (COSY, HETCOR, and COLOC) and chemical conversions. The steroidal saponin showed absence of haemolytic effects in the in vitro assay, but demonstrated a significant inhibition of the capillary permeability activity.