ASPERGILLAMIDE-A AND ASPERGILLAMIDE-B - MODIFIED CYTOTOXIC TRIPEPTIDES PRODUCED BY A MARINE FUNGUS OF THE GENUS ASPERGILLUS

Two isomeric linear peptides, aspergillamides A and B (1, 2), were iso lated from the mycelium of a cultured marine fungus of the genus Asper gillus. The producing strain (designated CNC-120), was obtained from a saline lake sediment sample collected from Acklins Island. the Bahama s. The structures of the new peptides were elucidated using comprehens ive 2D NMR methods. At 25 degrees C, in both acetone and dimethylsulfo xide, aspergillamide A exists as a 1:1 mixture of trans- and cis-amide rotational isomers (1a and 1b). Under identical conditions, aspergill amide B is predominantly in the cis-amide form. The absolute stereoche mistries of the amino acids in aspergillamide A were assigned as L by hydrolysis and comparison with commercial standards. Aspergillamide A showed modest irt virro cytotoxicity [IC50 = 16 mu g/ml] toward the hu man colon carcinoma cell line HCT-116. (C) 1998 Elsevier Science Ltd. All rights reserved.