Cycloartane triterpene glycosides from the roots of Astragalus melanophrurius

From the roots of Astragalus melanophrurius eight known saponins (1-8) were isolated. Based on spectral data (IR, 1H- and 13C-NMR, and FABMS), the structures were established as astrasieversianins II (1) and X (4), astragalosides I (2), II (3), IV (5) and VI (7), and cyclocanthosides E (6) and G (8). The isolates were evaluated in a broad range of bioassay systems and found to be inactive. Modest antibacterial activity was observed, however, as was immunomodulatory activity, as indicated by stimulation of isolated human lymphocytes.