Cycloartane-type glycosides from Astragalus amblolepis.

Five cycloartane-type triterpene glycosides were isolated from the methanol extract of the roots of Astragalus amblolepis Fischer along with one known saponin, 3-O-beta-D-xylopyranosyl-16-O-beta-D-glucopyranosyl-3beta,6alpha,16beta,24(S),25-pentahydroxy-cycloartane. Structures of the compounds were established as 3-O-beta-D-xylopyranosyl-25-O-beta-D-glucopyranosyl-3beta,6alpha,16beta,24(S),25-pentahydroxy-cycloartane, 3-O-[beta-D-glucuronopyranosyl-(1-->2)-beta-D-xylopyranosyl]-25-O-beta-D-glucopyranosyl-3beta,6alpha,16beta,24(S),25-pentahydroxy-cycloartane, 3-O-beta-D-xylopyranosyl-24,25-di-O-beta-D-glucopyranosyl-3beta,6alpha,16beta,24(S),25-pentahydroxy-cycloartane, 6-O-alpha-L-rhamnopyranosyl-16,24-di-O-beta-D-glucopyranosyl-3beta,6alpha,16beta,24(S),25-pentahydroxy-cycloartane, 6-O-alpha-L-rhamnopyranosyl-16,25-di-O-beta-D-glucopyranosyl-3beta,6alpha,16beta,24(S),25-pentahydroxy-cycloartane by using 1D and 2D-NMR techniques and mass spectrometry. To the best of our knowledge, the glucuronic acid moiety in cycloartanes is reported for the first time.