Largamides A-C, tiglic acid-containing cyclodepsipeptides with elastase-inhibitory activity from the marine cyanobacterium Lyngbya confervoides.

Three unusual tiglic acid-containing cyclodepsipeptides, possessing the revised regioisomeric structures for largamides A-C (1-3), have been isolated from the marine cyanobacterium Lyngbya confervoides collected from southeastern Florida. The two-dimensional structures were determined by NMR spectroscopy and the absolute configurations by chiral HPLC analysis of degradation products. Compounds 1-3 are moderate inhibitors of mammalian elastase activity in vitro with IC(50) values ranging from 0.53 to 1.41 microM.