Gonyaulax spp

Saxitoxin was first isolated from Alaskan butter clam Saxidomus giganteuSy but is actually produced by the dinoflagellate, Gonyaulax spp (i,2). More than a dozen related toxins have been isolated by several groups including ours (i). All of the toxins have the same unique tricyclic perhydropurine skeleton, and there were various speculations about the origin of the perhydropurine ring (I). 

Rapid-acting paralytic neurotoxins that blocks transient sodium channels and inhibits depolarization of nerve cells. They are some of the causative agents of paralytic shellfish poisoning (PSP). They are obtained from dinoflagellates (Gonyaulax spp., Alexandrium spp.) and cyanobacteria (Anabaena circinalis). 

Paralytic shellfish toxins in the dinoflagellate ProtogonyauZax =Gonyaulax) spp. and bivalves of temperate waters have been the subjects of extensive studies. In contrast, information on the occurrence of these toxins in tropical waters has been scarce. 

The production of YTXs by this species in culture was demonstrated a few years later [42]. Very recently, and following detection of YTXs from an unknown source in New Zealand shellfish resources, cultured isolates of G. spinifera were identified as the probable source of the toxins [43]. It cannot be ruled out that the list of toxigenic Gonyaulax spp. will increase in the near future, as new species from different parts of the world are isolated and tested. 

To date twelve toxins including saxitoxin have been isolated from various sources. The isolated toxins and their chromatographic and electrophoretic behavior are summarized in Table 1. Those toxins whose origins were identified as Gonyaulax spp. were named serially gonyautoxin-I — -VIII (abbreviated GTX-I — -VIII or GTX — GTXg). Neosaxitoxin... 

Neosaxitoxin (2) 0.70 0.54 7 Gonyaulax spp. Aphanizomenon flos-aquae shellfish, crabs, etc. (26)... 

Saxitoxins (see structure for Saxitoxin or SXT, CAS 35523-89-8, C10H17N7O4) are produced by Alex-andrium spp. (Gonyaulax) and several of the cyanobacteria. Heat-stable neurotoxic saxitoxins have a relaxant action on vascular smooth muscle. They inhibit the temporary permeability of sodium ion influx by binding I I with high affinity to a specific receptor site on the outside surface of the membrane... 

---