ABSTRACT
The cyanobacterial toxins are secondary metabolites synthesized within the cells of some species from at least four of the five orders of cyanobacteria. The toxins show great diversity, ranging from simple alkaloids to complex polycyclic compounds and cyclic peptides. In all probability, the characterized toxins illustrate only a small proportion of the total toxins of cyanobacteria, as most cyanobacterial species have not yet been examined for toxicity. The best-understood peptide toxin group, the microcystins, originally isolated from the genus Microcystis, have more than 60 molecular variants identified at the present time. Similarly the saxitoxin-related alkaloids in cyanobacteria show a family of compounds of differing toxicity, some of which are different from those of marine dinoflagellates (Onodera, Satake et al. 1997). By comparison with toxins identified from marine dinoflagellates (Baden and Trainer 1993), cyanobacteria have not yet been shown to possess polyether neurotoxins, though there have been numerous reports of uncharacterized neurotoxicity from cyanobacteria (Hawser, Capone et al. 1991; Baker et al. 2001).
