Microginins, Zinc Metalloproteases Inhibitors from the Cyanobacterium Microcystis aeruginosa

Eight new linear peptides, microginins 478 (1), 51-A (2), 51-B (3) and 91-A (4) to 91-E (8), congeners of microginin, were isolated from the cyanobacterium Microcystis aeruginosa. These structures were elucidated to be 1–8 on the basis of 2D NMR data and chemical degradation. These peptides inhibited aminopeptidase M (1, 2 and 6–8) and angiotensin-converting enzyme (1). The structure–activity relationship within a series of degradation and derivative products of microginin was investigated by the chemical studies.