STUDIES OF AUSTRALIAN ASCIDIANS .4. MOLLAMIDE, A CYTOTOXIC CYCLIC HEPTAPEPTIDE FROM THE COMPOUND ASCIDIAN DIDEMNUM MOLLE

A new cytotoxic cyclic heptapeptide, mollamide, has been isolated from the compound ascidian Didemnum molle. The structure of mollamide was initially deduced from one-dimensional and two-dimensional n.m.r. experiments at 300 MHz. The structure was confirmed by an X-ray crystallographic study, which showed the relative stereochemistry of the cyclic peptide. Hydrolysis of mollamide, and characterization of the amino acids by derivatization with N alpha-(5-fluoro-2,4-dinitrophenyl)-L-alanina (FDAA; Marfey's reagent) gave the absolute stereochemistry; all constituent amino acids were the L-isomers. Cytotoxicity data are reported.