Solanapyrones E-G, antialgal metabolites produced by a marine fungus

Three new alpha-pyrones, solanapyrones E (1), F (2), and G (3), in addition to the known phytotoxin solanapyrone C (4), were produced by an unidentifi ed filamentous marine fungus isolated from the surface of the green alga Ha limeda monile. The new solanapyrones were characterized by one and two-dime nsional NMR spectroscopic techniques, and the absolute configuration of 2 w as assigned by the Mosher method. The solanapyrones showed toxicity to the marine unicellular alga Dunaliella sp. at concentrations as low as 100 mu g ml(-1). The possible role of these compounds in phytotoxic associations be tween marine fungi and algae is discussed. (C) 1998 Elsevier Science Ltd. A ll rights reserved.