Solanapyrones e-g, antialgal metabolites produced by a marine fungus

Three new α-pyrones, solanapyrones E (1), F (2), and G (3), in addition to the known phytotoxin solanapyrone C (4), were produced by an unidentified filamentous marine fungus isolated from the surface of the green alga Halimeda monile. The new solanapyrones were characterized by one and two-dimensional NMR spectroscopic techniques, and the absolute configuration of 2 was assigned by the Mosher method. The solanapyrones showed toxicity to the marine unicellular alga Dunaliella sp. at concentrations as low as 100 μg ml −1. The possible role of these compounds in phytotoxic associations between marine fungi and algae is discussed.