Kasumigamide, an antialgal peptide from the cyanobacterium Microcystis aeruginosa

Kasumigamide (1), a novel antialgal tetrapeptide containing an N-terminal alpha-hydroxy acid, was isolated from the freshwater cyanobacterium Microcystis aeruginosa (NIES-87). Its structure was elucidated by two-dimensional H-1-H-1 and H-1-C-13 NMR correlation experiments and confirmed by mass spectral and amino acid analyses. The absolute stereochemistry of 1 was determined by chemical studies. This peptide showed an antialgal activity against the green alga Chlamydomonas neglecta (NIES-439).