Chemistry and biological activity of triterpenoid glycosides from Medicago sativa.

Ten triterpenoid glycosides have been isolated from the roots of Medicago sativa L. (Leguminosae) including eight new glycosides and two previously known, medicagenic acid 3-O-beta-D-glucopyranoside and hederagenin 3-O-[beta-D-glucopyranosyl(1-->2)-alpha-L-arabinopyranoside]. Four new saponins were identified as glycosides of medicagenic acid, four from hederagenin. Their structures were elucidated by a combination of chemical and spectroscopic techniques (IR, EI/MS, NMR 1H and 13C). In some cases we used fast atom bombardment mass spectra (FAB/MS), NMR 1H difference spectra (homonuclear double resonance, Overhauser effect), NMR 13C partially decoupled spectra (off resonance), and two-dimensional 1H-1H correlating spectra (COSY 1H-1H). The inhibitory effects of these glycosides on growth and seed germinations and on some phytopathogenic bacteria have also been tested.