Antimicrobial Prenylated Anthracene Derivatives from the Leaves of Harungana madagascariensis

Three new prenylated anthranoids, harunmadagascarins C (1) and D (2) and kenganthranol D (3), together with three known compounds (4-6) were isolated from the leaves of Harungana madagascariensis. Their structures were assigned by spectroscopic methods and by comparison with literature data. In the three new natural products 1-3, one or two prenyl groups are incorporated in furan, pyran, or cyclohexane rings in four different modes of annulation. Compounds 2, 4, and 6 were strongly active against the Gram-positive Bacillus megaterium.