Neoraudiol, a new isoflavonoid and other antimicrobial constituents from the tuberous root of Neorautanenia mitis (A. Rich) Verdcourt

A bioassay-directed fractionation of n-hexane and chloroform extracts of the tuberous roots of Neorautanenia mitis resulted in the isolation of a new isoflavonoid, named neoraudiol (1) and five known compounds: rautandiol A (2), neoduline (3), neotenone (4), pachyrrhizine (5) and 12a-hydroxylrotenone (6). The structure of the new compound was established on the basis of spectroscopic studies and comparison with known compounds. Isolated compounds exhibited broad spectrum antimicrobial activity ranging from 15 to 80 mg/ml, the most significant activity (MIC15.10 ± 0.5 mg/ml) was exhibited by neoraudiol. Structure–activity relationship is described.