Aeruginosins, protease inhibitors from the cyanobacterium Microcystis aeruginosa

Five new protease inhibitors, related to aeruginosins 298-A (5), 98-A (1) a nd 98-B (2), were isolated from the cyanobacterium Microcystis aeruginosa. Aeruginosins 98-C (3) and 101 (4) differed from 1 in the Hpla unit. Aerugin osin 298-B (6) lacked the argininol unit in 5. Aeruginosins 89-A (7) and 89 -B (8) were observed as the tautomers in HPLC because of the presence of th e argininal units. Structures 3, 4 and 6-8 were determined on the basis of spectral data and chromatographic analyses of degradation products. The abs olute stereochemistry of 1-8 was deduced by a combination of spectral and c hemical studies. (C) 1999 Elsevier Science Ltd. All rights reserved.