Scallops saxitoxin from

Saxitoxin, the best known example of this group, is a potent neurotoxin found in shellfish such as mussels, clams, and scallops. Saxitoxin is a sodium channel-blocking agent and is more toxic by inhalation than by other routes of exposure. Unlike oral intoxication with saxitoxin (paralytic shellfish poisoning), which has a relatively slow onset, inhala-tional intoxication with saxitoxin can be lethal in a few minutes. Saxitoxin could be used against our troops as an antipersonnel weapon, but because it cannot currently be chemically synthesized efficiently, or produced easily in large quantities from natural sources, it is unlikely to be seen as an area aerosol weapon on the battlefield. 

Shortly after we were successful in obtaining the structure of saxitoxin, Shimizu and colleagues at the University of Rhode Island purified the poison from east coast scallops and reported that the structure of the major poison from scallops and G. tamarensis. based on NMR studies, was 11-hydroxy saxitoxin which he called... 

Shimizu in 1978 published the structure of an interesting saxitoxin derivative, 1-N-hydroxysaxitoxin, which he isolated from scallops and called neosaxitoxin (23) as shown in Figure 2C. Subsequently Boyer in 1980 published the structure of neo-11-hydroxysaxitoxin sulfate and its epimer (24). 

In addition to these passive processes shellfish have been shown to actively modify the saxitoxins. Shimizu has shown (40) that scallops can remove both the N-l-hydroxyl and 11-hydroxysulfate groups from the saxitoxins. Sullivan has shown ( ) that enzymes in littleneck clams can remove the sulfamate or carbamate side chain, yielding the decarbamoyl toxins. This activity was not detected in either mussels or butter clams. With both sorts of modification the products are compounds that have higher potency and are likely to be bound in shellfish more strongly. 

Gonyautoxin-VII (9) was isolated from toxic scallops collected in the Bay of Fundy 28). The compound does not possess sulfate conjugation and was eluted very close to saxitoxin in Bio-Rex 70 ion-exchange chromatography. It was first considered to be identical with decarbamoylsaxitoxin (26), but the identity was excluded by direct comparison 28). 

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