ChemInform Abstract: Phomactins, Novel PAF Antagonists from Marine Fungus Phoma sp

Diterpenes phomactins B (1a), B1 (1c), B2 (2a), C (4), and D (5) were isolated from a marine fungus, Phoma sp. These structures were determined based on spectroscopic evidences, X-ray crystallography, and chemical conversion. We also determined the absolute configuration of 1a, 1c, and 2a by the advanced Mosher's method and circular dichroism. Phomactin D inhibited the binding of PAF to its receptors and PAF-induced platelet aggregation with IC 50 of 1.2×10 -7 M and 8.0×10 -7 M, respectively, while other compounds antagonized PAF action at higher concentrations