New triterpenoid saponin from the aerial part of Welw ex. Bak. (Fabaceae) and their antibacterial activities.

The chemical investigation of the aerial part of led to isolation of a new triterpenoid glycoside named Canescensoside () and four known compounds including longispinogenin-3---D-glucuronopyranoside (), -sitosterol-3---D-glucoside (), apigenin-7---D-glucopyranoside () and apigenin-7--[-L-rhamnopyranosyl-(1→3)--D-glucopyranoside] (). Structures of compounds were assigned by interpretation of their spectral data, mainly 1D and 2D NMR, HRESIMS, and by comparison with the reported data. The MeOH extract, EtOAc and -BuOH fractions as well as isolated compounds were tested for their antibacterial activities against four bacteria strains among which, two Gram-negative ( ATCC 76110 and ATCC 8739) and two Gram-positive ( ATCC 29212 and ATCC 25923) bacteria using the broth microdilution method. The MeOH extract and EtOAc fraction exhibited significant activities (MIC values ranging from 128 to 512 g/mL) against all the tested bacteria. Compounds and showed the lowest MIC values of 55.47 and 50.40 M, respectively.