Structural elucidation of cyanobacterial peptides encoded by peptide synthetase gene in Anabaena species

During our biosynthesis study of cyanobacterial peptides including microcystins, we investigated the metabolic peptides in the hepatotoxic cyanobacteria, Anabaena sp. strains 90 and 202A2, in which the genetic analysis of the peptide synthetase had been carried out. For the exhaustive screening of cyanobacterial peptides, an analytical method using ESI-LC/MS on-line photodiode array detection was successfully developed and applied. Based on the analytical results, two groups of peptides, the cyclic depsipeptides having a 3-amino-6-hydroxy-2-piperidone moiety, anabaenopeptilides, and the cyclic peptides possessing an ureido linkage, anabaenopeptins, were isolated together with microcystins from both strains. Consequently, we confirmed the structures including the stereochemistry of the anabaenopeptilides encoded by the sequencing peptide synthetase genes in Anabaena strain 90.