Secondary Metabolites from the Roots of Astragalus trojanus

Six novel cycloartane-type glycosides were isolated from the roots of Astragalus trojanus. Two of these, compounds <BO>1</BO> and <BO>2</BO>, have (20R,24S)-epoxy-3β,6α,16β,25-tetrahydroxycycloartane as the aglycon, while compounds <BO>3</BO>−<BO>6 </BO>possess 3β,6α,16β,(24S),25-pentahydroxycycloartane as the aglycon. The saccharide moieties linked to the C-3, C-6, and C-24 or C-25 positions of the aglycons in <BO>1</BO>−<BO>6</BO> contained either xylopyranose, glucopyranose, rhamnopyranose, or arabinopyranose units. Structure elucidation of compounds <BO>1</BO>−<BO>6</BO> was accomplished through the extensive use of 1D and 2D NMR techniques. In addition, a new oleanene glycoside (<BO>7</BO>) and a new tryptophan derivative (<BO>8</BO>) were also isolated and characterized.