Definition: Cyclic heptapeptides found in MICROCYSTIS and other CYANOBACTERIA. Hepatotoxic and carcinogenic effects have been noted. They are sometimes called cyanotoxins, which should not be confused with chemicals containing a cyano group (CN) which are toxic.
microcystin microcystins have the general structure cyclo(D-Ala-L-X-D-erythro--methylisoasp-L-Y-Adda-D-isoGlu-N-methyldehydroAla) where X and Y are variable L-amino acids;