Blue-green algal toxin microcystin

Hermansky, S.J., Stohs, S.J., Markin, R.S., Murray, W.J. (1990a). Hepatic lipid peroxidation, sulfhydryl status, and toxicity of the blue-green algal toxin microcystin-LR in mice. J. Toxicol. Environ. Health 31 71-91. 

Figure 1. Structure of the blue-green algal toxin microcystin-LR. Besides the two variable L-amino acids, leucine and arginine, the microcystin contains three D-amino acids (glutamic acid, alanine and methylaspartic acid) and two unusual amino acids, N-methyl-dehydroalanine (Mdha) and 3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-deca-4,6-dienoic acid (Adda) (see Ref. 4).

Cyanobacteria toxins (sometimes referred to as blue green algal toxins) are represented in this entry by Aplysiatoxins, which are toxic to the skin, and anatoxin a (CAS 64285-06-9, C10H15NO) and anatoxin a (S) (very fast death factor), which are neurotoxins. Saxitoxin, discussed earlier, and neo-saxitoxin are both neurotoxins that may also be classified as cyanobacterial toxins. A large variety of other toxins is produced by cyanobacteria, but is not as well documented. These include lyngbyatoxin (dermatotoxic) cyclic peptides predominantly microcystins, nodularins, and cylindro-spermopsin (hepatotoxins) endotoxins and other substances as yet undescribed, including additional tumor promoters. 

Tetrodotoxin, from the puffer fish and other members of the order Tetraodontiformes, is a neurotoxin much like saxitoxin in its mechanism of action, toxicity, and physical characteristics. Palytoxin, from the soft coral Palythoa tuberculosa, is extremely toxic and quite stable in impure form, but difficulty of production or harvest from nature reduces the likelihood that an aggressor would use it as an MCBW. The brevetoxins, commonly associated with red tide dinoflagellate blooms, and the blue-green algal toxins like microcystin, a hepatotoxin, have limited toxicity. 

Blue-green algae (cyanobacteria) can occur in surface water bodies used for water supply Some species of cyanobacteria contain toxins of concern to human health (e.g. microcystins), and these can be released when algal cell walls are ruptured, There is a wide range of potential toxins and it appears that not all of the possible toxins have been identified. 

Toxins such as microcystin LR and associated substances can be very difficult to analyse at low concentrations in water. Therefore, it is preferable to control blue-green algae by preventing algal blooms in source waters. There are treatment options for microcystin LR and related substances, but these require careful assessment for example, it is particularly important to ensure that algal cells are removed. 

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