Micropeptins 88-A to 88-F, chymotrypsin inhibitors from the cyanobacterium Microcystis aeruginosa (NIES-88)

Micropeptins 88-A to 88-F (1–6) have been isolated from the cyanobacterium Microcystis aeruginosa (NIES-88). Their structures were determined by two-dimensional 1H-1H and 1H-13C NMR correlation experiments and confirmed by mass spectral and amino acid analyses. Their absolute stereochemistries were deduced by a combination of spectral and chemical studies. Micropeptins 88-A and 88-C to 88-F inhibited chymotrypsin potently with IC50 of 0.4–10.0 μg/mL.