Structural studies on cyanoginosins-LR, -YR, -YA, and -YM, peptide toxins from Microcystis aeruginosa

Abstract
The structures of the hepatotoxins of general name cyanoginosins-XY are proposed to be cyclo-D-Ala-L-X-erythro-β-methyl-D-isoAsp-L-Y-Adda-D-isoGlu-N-methyldehydroAla (1) where X and Y represent variable amino acids and Adda is 3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6-dienoic acid (2). The structural studies on four variant toxins utilised n.m.r. and mass spectral methods analogous to those recently used to determine the structure of cyanoginosin-LA. [graphic omitted] (1)