Cycloartane glycosides from Astragalus campylosema Boiss. ssp. campylosema

Four cycloartane glycosides, 3-O-[alpha-l-arabinopyranosyl-(1-->2)-beta-d-xylopyranosyl]-3beta,6alpha,16beta,23alpha,25-pentahydroxy-20(R),24(S)-epoxycycloartane (1), 3-O-[alpha-l-arabinopyranosyl-(1-->2)-beta-d-xylopyranosyl]-16-O-hydroxyacetoxy-23-O-acetoxy-3beta,6alpha,25-trihydroxy-20(R),24(S)-epoxycycloartane (2), 3-O-[alpha-l-arabinopyranosyl-(1-->2)-beta-d-xylopyranosyl]-3beta,6alpha,23alpha,25-tetrahydroxy-20(R),24(R)-16beta,24;20,24-diepoxycycloartane (3), 3-O-[alpha-l-arabinopyranosyl-(1-->2)-beta-d-xylopyranosyl]-25-O-beta-d-glucopyranosyl-3beta,6alpha,16beta,25-tetrahydroxy-20(R),24(S)-epoxycycloartane (4), along with three known cycloartane glycosides were isolated from the MeOH extract of the roots of Astragalus campylosema ssp. campylosema. Their structures were established by the extensive use of 1D- and 2D-NMR experiments along with ESIMS and HRMS analysis. The occurrence of the hydroxyl function at position 23 (1-2) and of the ketalic function at C-24 (3) are very unusual findings in the cycloartane class.