Apramides A-G, novel lipopeptides from the marine cyanobacterium Lyngbya majuscula

Six new metabolites have been isolated from a lyngbyastatin 2-producing strain of the marine cyanobacterium Lyngbya majuscula collected at Apra Harbor, Guam, and their structures elucidated. These linear lipopeptides have been assigned the trivial names apramides A-F (1-6). From a more recent collection of this cyanobacterium, a structurally related compound, apramide G (7), has been found instead of apramides A-F (1-6). Structure elucidation of the lipopeptides 1-7 is based on spectroscopic techniques and chiral chromatography of hydrolysis products. The apramides appear as NMR-spectroscopically distinguishable conformers in solution, and this has been ascribed to the presence of a thiazole-containing modified amino acid unit.