Toxicants, natural saxitoxin

The fargefs for natural biological toxins include ion channels and receptors for transmitfers. At least four parts of fhe volfage-gafed sodium charmels are binding sifes for extremely toxic natural products. " Tetrodotoxin (Fig. 30-16), which is found in the puffer fish, certain newts, and venom of fhe blue-ringed octopus, and also the shellfish poison saxitoxin (Fig. 

Llewellyn, L.E. (2006). Saxitoxin, a toxic marine natural product that targets a multitude of receptors. Nat. Prod. Rep. 23 200-2. 

Saxitoxin is a naturally occurring substance in dino-flagellates and taken up by shellfish. Consumption of the shellfish leads to toxicity. Aside from the knowledge that these organisms serve as a source of exposure, the environmental fate of the chemical... 

Saxitoxin and its derivatives are water-soluble compounds that bind to the voltage-sensitive sodium channel, blocking propagation of nerve-muscle action potentials. The natural route of exposure to these toxins is oral. In a BW scenario, the most likely route of delivery is by inhalation or toxic projectile. In addition, saxitoxin could be used in a confined area to contaminate water supplies. 

Marine toxins may be developed from marine organisms. Examples include saxitoxin, tetrodotoxin, palytoxin, brevetoxins, and microcystin. Saxitoxin is a sodium-channel blocker and is most toxic by inhalation compared to the other routes of exposure. Saxitoxin and tetrodotoxin are similar in mechanical action, toxicity, and physical attributes. They can be lethal within a few minutes when inhaled. It has not yet been chemically synthesized efficiently, or easily created in large quantities from natural sources. Palytoxin is produced from soft coral and is highly toxic. It is, however, difficult to produce or harvest from nature. 

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. 

Tetrodotoxin, from the puffer fish and other members of the order Tetraodontiformes, is a neurotoxin much like saxitoxin in its mechanism of action, toxicity, and physical characteristics. Palytoxin, from the soft coral Palythoa tuberculosa, is extremely toxic and quite stable in impure form, but difficulty of production or harvest from nature reduces the likelihood that an aggressor would use it as an MCBW. The brevetoxins, commonly associated with red tide dinoflagellate blooms, and the blue-green algal toxins like microcystin, a hepatotoxin, have limited toxicity. 

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