Saxitoxin (STX) is the best-known paralytic shellfish toxin (PST), although other related compounds have been reported, such as neosaxitoxin (NSTX), the 11-alpha and 11-beta-O-sulphates of saxitoxin and neosaxitoxin, and carbonyl-N-sulphate derivatives of saxitoxin and neosaxitoxin. STX is a neurotoxin naturally produced by certain species of marine dinoflagellates and cyanobacteria. Ingestion of saxitoxin is responsible for the human illness known as paralytic shellfish poisoning (PSP). In fact, the term saxitoxin originates from the species name of the butter clam (Saxidomus giganteus) in which it was first recognized. But, the term saxitoxin can also refer to the entire suite of related neurotoxins produced by these microorganisms, which include pure saxitoxin (STX), neosaxitoxin (NSTX), gonyautoxins (GTX) and decarbamoylsaxitoxin (dcSTX).
-V558.gif)