Prenylated isoflavanone from Erythrina eriotricha.

Bioassay-directed fractionation of a methylene chloride extract of the root bark of Erythrina eriotricha resulted in the isolation of a novel isoflavanone, named eriotrichin B, and the five known pterocarpans, isonorautenol, erybraedin A, erybraedin C, erybraedin D and erybraedin E. The structure of the new compound has been investigated by extensive spectroscopic studies, including 2D NMR and chemical evidence. The in vitro antimicrobial spectrum and potencies of the isolated compounds are also reported.