Kohamamides A, B, and C, Cyclic Depsipeptides from an Okeania sp Marine Cyanobacterium

Kohamamides A, B, and C (13), new cyclic depsipeptides that belong to the kulolide superfamily, were isolated from an Okeania sp. marine cyanobacterium. Their structures were elucidated by spectroscopic analyses and degradation reactions. Kohamamide B (2) exhibited moderate cytotoxicity against HL60 cells. Although many natural products in the kulolide superfamily have been isolated from cyanobacteria collected in various parts of the world, kohamamides 13 are the first members to be isolated from the East Asian marine environment. In addition, unlike other members of this superfamily, kohamamides 13 contain a Leu residue adjacent to the Pro residue, rather than another lipophilic amino acid.