Antimicrobial triterpenes from Poulsenia armata miq. standl.

Crude petroleum ether extract from the bark of Poulsenia armata showed antimicrobial activity. Activity-guided fractionation led to the isolation and structure elucidation of two active new triterpene derivatives, the stearate of glut-5-en-3β-ol (1) and 3β,28-diacetoxyurs-12-ene (4), for the first time as naturally occurring compounds. Compound 4 has previously been synthesized. The structures were determined by 1D- and 2D-NMR spectroscopy, mass spectrometry and chemical transformations. This is the first report on the chemistry and pharmacology of the genus.