Antibacterial Isoflavans from Eysenhardtia adenostylis

Eysenhardtia adenostylis Baillon (Fabaceae) grows in Central America. This plant's (local name "Taray") stem and wood water extract are used as remedies for renal problems as a traditional medicine in Nicaragua. In this report, four known isoflavan constituents were isolated as antibacterial compounds from F. adenostylis wood. The dried wood powder was extracted with ethanol at room temperature and the extract was separated into a chloroform-methanol-water (4：4：3) mixture. The lower layer was applied to a silica gel column. The chloroform-methanol (10：1) eluate from the column gave a crude fraction. This fraction was further separated by repeated silica gel columns to give amorphaquinone (1)1, 2), mucronulatol (2)3-5), lonchocarpin (3)6) and pedulone (4)7, 8) These compounds were identified on the basis of comparing the physical propeties and spectral data with those in literature. Furthermore, from the fact that each compound has no optical rotation, compounds 1-4 were identified as racemate at C-3. The antibacterial activities of ethanol extract and compounds 1-4 were similar or stronger than methyl p-hydroxybenzoate (as the positive control) with minimum inhibitory concentration (MIC) assay of three kinds of bacteria.