New derivatives of saikosaponins.

Abstract

In the course of studies on the metabolism of saikosaponins, which are the main constituents of Bupleurum falcatum L., five new compounds derived from saikosaponins a, c and d were isolated after incubation with acid and snail enzyme. On incubation of saikosaponins a and c at 60°C in a 1 N sulfuric acid-dioxane solution, saikosaponins g and i possessing a homoannular diene moiety at C-9 (11), 12 were isolated, and their structures were elucidated as 3β, 16β, 23, 28-tetrahydroxyoleana-9 (11), 12-diene 3-O-β-D-glucopyranosyl-(1→3)-β-D-fucopyranoside and 3β, 16β, 28-trihydroxyoleana-9 (11), 12-diene 3-O-β-D-glucopyranosyl-(1→6)-[α-L-rhamnopyranosyl-(1→4)]-β-D-glucopyranoside, respectively. Furthermore, on incubation of saikosaponins b1, g and b2 with snail enzyme for 12h at 37°C, prosaikogenins A, H, and D were formed ; they were identified as the 3-β-D-fucopyranosides of saikogenins A, H and D.