Isolation of homodolastatin 16, a new cyclic depsipeptide from a Kenyan collection of Lyngbya majuscula.

An examination of an organic extract of the cyanobacterium Lyngbya majuscula, collected from Wasini Island off the southern Kenyan coast, led to the isolation of the known cyclic depsipeptide antanapeptin A (1), recently isolated from a Madagascan collection of L. majuscula, and a new bioactive cyclic depsipeptide, homodolastatin 16 (2). The structures of these two compounds were determined from NMR and mass spectrometry data. Homodolastatin 16, a higher homologue of the potential anticancer agent dolastatin 16, exhibited moderate activity against oesophageal and cervical cancer cell lines.