Antibacterial triterpenoids from the bark of Sonneratia alba (Lythraceae).

The new lupane-type triterpenoid, 3β-hydroxy-lup-9(11),12-diene, 28-oic acid (1), along with two known lupane-type triterpenoids, lupeol (2) and lupan-3β-ol (3), were isolated from the bark of Sonnetaria alba. The structure of the new compound was elucidated on the basis of spectroscopic and mass spectrometric data analysis. Using the broth microdilution method, all compounds exhibited antibacterial activity against the Gram-positive bacteria Staphylococcus aureus ATCC 6538 and Streptococcus mutans ATCC 25175, with minimum inhibitory concentrations ranging from 15-33 to 35-55 μg/mL, respectively.