Myxaoside A, a new triterpenoid saponin from Cordia myxa L. (Boraginaceae).

The phytochemical study of Cordia myxa L. led to the isolation, through chromatographic techniques, of a new triterpenoid saponin, 3-O-[α-L-rhamnopyranosyl-(1→3)-(6-O-acetyl-ß-D-glucopyranosyl)]-22ß-hydroxyolean-12-ene (3) namely Myxaoside A, together with three known compounds, Soyasaponine I (1), oleanolic acid (2), and 3-O-acetyl-oleanolic acid (4). All structures were established, based on 1 & 2D-NMR spectroscopic analysis and comparison with previous published reports. Compound 1-4 were evaluated for their antibacterial activity on various strains of bacteria including Salmonella typhi, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae and Vibrio cholerae. It appears that compounds 1 and 3 were active on all the tested microbial species, while compounds 2 and 4, shown no significant effect on S. aureus and K. pneumoniae at low concentrations 6.5 mg/mL and 3.0 mg/mL.