Cyanobacteria, toxins

Acute poisoning of humans by freshwater cyanobacteria as occurs with paralytic shellfish poisoning, while reported, has never been confirmed. Humans are probably just as susceptible as pets, livestock, or wildlife but people naturally avoid contact with heavy waterblooms of cyanobacteria. In addition, there are no known vectors, like shellfish, to concentrate toxins from cyanobacteria into the human food chain. Susceptibility of humans to cyanobacteria toxins is supported mostly by indirect evidence. In many of these cases, however, if a more thorough epidemiological study had been possible these cases probably would have shown direct evidence for toxicity. 

Cyanobacteria toxins are toxins produced by certain species of blue-green algae that have become a major environmental and public health concern. The behavior of cyanotoxins during chlorination treatment has been recently reviewed by Merel et al. [129]. Chlorination DBFs have been reported only for the hepatotoxins microcystin-LR and cylindrospermopsin. Other cyanotoxins, such as nodularins, saxitoxins, and anatoxins, have yet to be investigated. Different isomers of six chlorination products of microcystin-LR have been characterized dihydroxy-microcystin, monochloro-microcystin, monochloro-hydroxy-microcystin, monochloro-dihydroxy-microcystin, dichloro-dihydroxy-microcystin, and trichloro-hydroxy-microcystin. Only two chlorination DBFs have been reported so far for cylindrospermopsin 5-chloro-cylindros-permopsin and cylindrospermopsic acid [129]. Chlorination of microcystin, cylindrospermopsin, and nodularins seems to reduce the mixture toxicity however, this aspect has not been extensively studied [129]. 

Both seafood toxins and cyanobacteria toxins are water-based diseases. 

Certain cyanobacteria toxins have structural/functional similarities to certain paralytic shellfish toxins, especially saxitoxin and neosaxitoxin. 

Cyanobacterial toxins (both marine and freshwater) are functionally and chemically a diverse group of secondary chemicals. They show structure and function similarities to higher plant and algal toxins. Of particular importance to this publication is the production of toxins which appear to be identical with saxitoxin and neosaxitoxin. Since these are the primary toxins involved in cases of paralytic shellfish poisons, these aphantoxins could be a source of PSP standards and the study of their production by Aphanizomenon can provide information on the biosynthesis of PSP s. The cyanobacteria toxins have not received extensive attention since they have fewer vectors by which they come in contact with humans. As freshwater supplies become more eutrophicated and as cyanobacteria are increasingly used as a source of single cell protein toxic cyanobacteria will have increased importance (39). The study of these cyanobacterial toxins can contribute to a better understanding of seafood poisons. 

This chapter reviews the nitrogen-containing neurotoxic compounds produced by cyanobacteria, and follows an earlier review in this series which more broadly covered the alkaloid chemistry of these life forms from the marine environment [3]. A description of the discovery, isolation, structural elucidation, biosynthesis, mechanism of action, structure-activity relationship (SAR), and some aspects of chemical synthesis of cyanobacteria toxins is provided. 

This hepatotoxin first appeared in tropical and subtropical waters of Australia, resulting in an alkaloid hepatotoxin with a completely different mechanism of toxicity. The possible incidence of this cyanobacteria toxin was first reported by By th (1980). An outbreak of hepatoenteritis occurred in 1979 at Palm Island, Queensland, Australia, when the population was supplied with drinking water from a... 

Maizels, M., Budde, W.L. 2004. A LC/MS method for the determination of cyanobacteria toxins in water. Analytical Chemistry 76 1342-1351. 

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. 

Soares, R.M., Magalhaes, V.E. and Azevedo, M.E.O. Accumulation and depuration of microcystins (cyanobacteria toxins) in Tilapia rendalli (Cichlidae) under laboratory conditions, Aquat. Toxicol. 70(1), 1, 2004. 

Carmichael, W.W. and Li, R.H., Cyanobacteria toxins in the Salton Sea, Saline Systems, 2, 2006. Welker, M. et al., Microcystins (cyanobacterial toxins) in surface waters of rural Bangladesh—pilot study, J. Water Health, 3, 325, 2005. 

Svrcek, C. and Smith, D.W., Cyanobacteria toxins and the current state of knowledge on water treatment options a review, J. Environ. Eng. ScL, 3, 155, 2004. 

Microcystis, Nostoc, and Oscillatoria (Planktothrix). Cyanobacteria toxins (cyanotoxins) include cytotoxins and biotoxins (neurotoxins anatoxin-a, anatoxin-a(s) and saxitoxins, and the hepatotoxins microcystins MCs, and nodularins), with biotoxins being responsible for acute lethal, acute chronic, and subchronic poisonings of wild/domestic animals and humans. In most of the reported cases, afflicted animals consumed water from water bodies where there was an obvious presence of cyano-bacterial scum on the water surface. More recent measurements of cyanobacterial toxins using sensitive modem analytical methods have often revealed high frequencies of toxic blooms even when animal poisonings have not been reported. 

Diehnelt, C.W., Peterman, S.M., and Budde, W.L. (2005) Liquid chromatography-tandem mass spectrometry and accurate m/z measurements of cyclic peptide cyanobacteria toxins. Trends Anal. 

Bacteria and protozoa in water can produce toxins that can cause illness or even death. Toxins prodnced in rivers, lakes, and reservoirs by cyanobacteria including Anabaena, Microcystis, and Nodularia have cansed adverse health effects in Australia, Brazil, England, and elsewhere in the world. There are abont 40 species of cyanobacteria that produce toxins from six chemical gronps. Cylindrospermopsin toxin (below) prodnced by cyanobacteria has poisoned people who have con-snmed water contaminated by the toxin. Surface scums of cyanobacteria are likely to have especially high levels of cyanobacteria toxins. 

Carmichael, W.W., 1981. Freshwater Blue-Green Algae (Cyanobacteria) Toxins—A Review, vol. 1. Plenum Press, New York, NY. 

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