Steroidal saponins from the bulbs of Lilium longiflorum and their antitumour-promoter activity.

Two new spirostanol saponins and two new furostanol saponins were isolated from the fresh bulbs of Lilium longiflorum together with several known saponins. The structures of new compounds were determined to be (25S)-spirost-5-ene-3 beta, 27-diol 3-O-(O-alpha-L-rhamnopyranosyl-(1-->2)-O- [alpha-L-arabinopyranosyl-(1-->3)]-beta-D-glucopyranoside), (25R)-27-O-[(S)-3-hydroxy-3-methylglutaryl]-spirost-5-ene-3 beta,27 diol 3-O-(O-alpha-L-rhamnopyranosyl-(1-->2)-O-[alpha-L-arabinopyranosyl -(1-->3)] - beta-D-glucopyranoside), 22-O-methyl-26-O-beta-D-glucopyranosyl-(25R)-furost-5-ene-3 beta,22 xi, 26-triol 3-O-(O-alpha-L-rhamnopyranosyl-(1-->2)-O-[alpha-L- arabinopyranosyl-(1-->3)]-beta-D-glucopyranoside) and 22-O-methyl-26-O-beta-D-glucopyranosyl-(25R)-furost-5-ene-3 beta, zeta, 26-triol 3-O-(O-alpha-L-rhamnopyranosyl-(1 --> 2)- O-[beta-D-xylopyranosyl-(1 --> 3)]-beta-D-glucopyranoside). The isolated saponins and their derivatives were examined for inhibitory activity on 12-O-tetradecanoylphorbol-13-acetate (TPA)-stimulated 32P-incorporation into phospholipids of HeLa cells as the primary screening test to find new antitumour-promoter compounds.