New Flavonoids from Boldoa purpurascens Cav.

Phytochemical analysis of the leaves of Boldoa purpurascens Cav. led to isolation of four flavone glycosides, three of which are new compounds. Their structures have been determined by mass spectrometry and by 1 D and 2 D NMR analysis, i.e., 4',5-dihydroxy-6,7-methylenedioxyflavonol 3-O-alpha-L-rhamnopyranosyl-(1 -> 2)-beta-D-xylopyranoside (1), 4',5-dihydroxy-6,7-methylenedioxyflavonol 3-O-beta-D-xylopyranoside (2), and 4',5-dihydroxy-6,7-methylenedioxyflavonol 3-O-alpha-L-rhamnopyranosyl-(1 -> 2)-beta-D-glucopyranoside (3). The known compound was 4',5-dihydroxy-6,7-methylenedioxyflavonol 3-O-beta-D-glucopyranoside (4). The aglycone 4',5-dihydroxy-6,7-methylenedioxyflavonol is known as gomphrenol. Compounds 1 and 2 failed to show antifungal activity when tested against three different strains of fungi, i.e., Fusarium culmorum, Botrytis cinerea, and Aspergillus flavus.