NEOMANGICOLS - STRUCTURES AND ABSOLUTE STEREOCHEMISTRIES OF UNPRECEDENTED HALOGENATED SESTERTERPENES FROM A MARINE FUNGUS OF THE GENUS FUSARIUM

Three novel sesterterpenes, neomangicols A-C (1-3) were isolated from the mycelial extract of a marine fungus belonging within the genus Fus arium. The carbon skeleton of the neomangicols is undescribed and cons titutes a new class of C-25 rearranged sesterterpenes. The structures of the new metabolites were determined by 1D and 2D NMR methods, and t he absolute configuration of 3 was determined by Mosher ester analysis of a diacetonide derivative. The configurations of the three stereoce nters in the side-chain were assigned on the basis of molecular modeli ng and NOESY NMR correlations observed for several diacetonide derivat ives of 3. Neomangicols A and B are cytotoxic against HCT-116 human co lon carcinoma in in vitro evaluation, while neomangicol B inhibits the growth of the Gram-positive bacterium Bacillus subtilus with a potenc y similar to that of the antibiotic gentamycin.