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- β - D -glucopyranosyl)]-22 β -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.