A new depsipeptide, cyanopeptolin 954 (1), was isolated from the freshwater cyanobacterium Microcystis aeruginosa NIVA Cya 43. The structure of the compound was elucidated by chemical and spectroscopic analyses, including 2D NMR and GC-MS of the hydrolysate. The major structural differences compared to previously characterized heptadepsipeptides of Microcystis are the replacement of the basic a...