Antimicrobial anthraquinones from Morinda angustifolia

Investigation on Morinda angustifolia resulted in the isolation of a new anthraquinone, 1,8-dihydroxy-2-methyl-3,7-dimethoxyanthraquinone (1), along with five known analogues, lucidin 3-O-β-primeveroside (2), 1,3-dihydroxy-2-methylanthraquinone (3), lucidin- ω -ethyl ether (4), lucidin-ω-butyl ether (5) and damnacanthol (6). The new compound demonstrated significant antimicrobial activity against Bacillus subtilis, Escherichia coli, Micrococcus luteus, Sarcina lutea, Candida albicans and Saccharomyces sake.