PARALYTIC SHELLFISH TOXINS: THEIR ORIGIN, CHARACTERISTICS AND METHODS OF DETECTION: A REVIEW

Paralytic shellfish toxin derivatives of saxitoxin (STX) are a group of nonprotein toxins associated with shellfish that are derived intracellularly from dinoflagellate algal cells such as Alexandrium catanella, A. tamarensis, and Gymnodinium catenatum. Recent reports indicate that pure cultures of bacteria harbored by the dinoflagellates intracellularly are capable of producing several of the toxins. The fundamental structure is that of saxitoxin, with 17 derivatives presently recognized, all of which exhibit varying levels of sodium channel blockage of neurons, resulting in neurological symptoms and paralysis at sufficiently high dosage. The toxins can be purified using adsorption chromatography on Sephadex G-15 or Bio-gel P-2 followed by cation-exchange chromatography. The toxins are readily resolved with silica gel thin layer chromatography, and can be visualized by oxidation with H2O2 resulting in highly fluorescent derivatives. In recent years the mouse bioassay has been supplemented with ELISA assays, HPLC for resolution followed by post-column oxidative derivatization for detection and quantitation of the various derivatives, as well as a mammalian neuroblastoma cell assay, which is highly specific for sodium channel blocking agents.