Cytotoxic steroidal saponins from the rhizomes of Asparagus oligoclonos

Two new steroidal saponins, aspaoligonins A (2) and B (3), were isolated from the methanolic extract of the rhizomes of Asparagus oligoclonos together with a known spirostanol saponin, asparanin A (1). Aspaoligonins A and B were characterized as (25S*)-5beta-spirostan-3beta,17alpha-diol 3-O-beta-D-glucopyranosyl (1-->2)-beta-D-glucopyranoside and (25S*)-5beta-spirostan-3beta,17alpha-diol 3-O-alpha-L-rhamnopyanosyl (1-->4)-beta-D-xylopyranosyl-(1-->2)]-beta-D-glucopyranoside, respectively, by spectrometric analyses including HRFABMS and 2D NMR. Compounds 1-3 were cytotoxic against five human tumor cell lines with IC50 values of 2.05-2.84 microg/mL.