Steroidal saponins from Hosta longipes and their inhibitory activity on tumour promoter-induced phospholipid metabolism of HeLa cells.

Three new spirostanol saponins and two new furostanol saponins were isolated from the underground parts of Hosta longipes. Their structures were determined to be (25R)-5 alpha-spirostane-2 alpha, 3 beta-diol (gitogenin) 3-O-{O-alpha-L -rhamnopyranosyl-(1-->2)-beta-D-galactopyranoside}, gitogenin 3-O-{O-alpha-L-rhamnopyranosyl-(1-->2) -O-[beta-D-glucopyranosyl-(1-->4)]-beta-D-galactopyranoside-, (25R)-5 alpha-spirostan-3 beta-ol (tigogenin) 3-O-{O-alpha-L-rhamnopyranosyl-(1-->2) -O-[beta-D-glucopyranosyl-(1-->4)]-beta-D-galactopyranoside-, 26-O-beta-D-glucopyranosyl-22-O-methyl-(25R)-5 alpha-furostane-2 alpha,3 beta, 22 xi,26-tetrol 3-O-{O-alpha-L-rhamnopyranosyl -(1-->2)-beta-D-galactopyranoside} and 26-O-beta -D-glucopyranosyl-22-O-methyl-(25R)-5 alpha-furostane-2 alpha,3 beta,22 xi,26-tetrol 3-O-{O-alpha-L -rhamnopyranosyl-(1-->2)-O-[beta-D-glucopyranosyl -(1-->4)]-beta-D-galactopyranoside}, respectively. The isolated saponins and their derivatives were examined for inhibitory activity on 12-O-tetradecanoylphorbor-13-acetate-stimulated 32P-incorporation into phospholipids of HeLa cells as the primary screening test to find new antitumour-promoter compounds.