Cyclic peptide hepatotoxins

Two recent studies systematically compared the efficiency of several reversed-phase columns (fully porous, partially porous, and monolithic) in the separation of microcystins nodularins and cyclic peptidic hepatotoxins (123,124). Many of the tested short, narrow-bore, reversed-phase columns produced excellent results in those separations even on a traditional low-pressure gradient HPLC system. The solventsaving benefits can be received without compromising the quality of the separation. The typical run time ranged between 3 and 4 min. 

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. 

Cyanobacteria known to produce hepatotoxins include species of Microcystis (32-36), Anabaena (37-40), Nostoc (41,42), Oscillatoria (43,44) and the brackish water Nodularia spumigena (45,46). These cyanobacteria produce a wide range of toxins including neurotoxic alkaloids, lipopolysaccharides, phenolic compounds and most importantly, the cyclic hepatotoxic peptides microcystins and nodularins. Since both microcystins and nodularins were recently discovered even in shellfish (47) and tropical fish species (48), and a nodularin variant was isolated in Papua New Guinea also from the tropical marine sponge Theonella swinhoei (49), marine prokaryotes are apparently producing identical toxins as the cyanobacteria. However, since this nodularin variant was isolated from a marine sponge it may well be produced by a microbial symbiont. 

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