saxitoxint

Saxitoxin is a potent neurotoxin produced by certain species of marine dinoflagellates, cyanobacteria, and some freshwater plankton. It is primarily responsible for paralytic shellfish poisoning (PSP), a type of foodborne illness that affects humans and marine animals. Saxitoxin was first isolated in the 1950s from the butter clam (*Saxidomus giganteus*), which gave the toxin its name.

The chemical structure of saxitoxin is a tricyclic guanidine alkaloid, and it acts by blocking voltage-gated sodium channels in nerve and muscle cells. This interference prevents the transmission of nerve impulses, leading to paralysis. Saxitoxin is highly stable and resistant to heat, making it difficult to destroy through cooking or processing. It is also highly soluble in water, which contributes to its persistence in the environment.

Saxitoxin is produced by dinoflagellates such as *Alexandrium*, *Gymnodinium*, and *Pyrodinium*, as well as certain cyanobacteria like *Anabaena* and *Aphanizomenon*. Filter-feeding shellfish, such as mussels, clams, and oysters, accumulate saxitoxin by ingesting these toxic algae. When humans consume contaminated shellfish, saxitoxin can cause symptoms ranging from tingling lips and tongue to paralysis, respiratory failure, and death in severe cases. The lethal dose for humans is estimated to be around 1–2 milligrams, depending on body weight.

Monitoring and regulation of shellfish harvesting areas are critical to prevent saxitoxin exposure. Public health agencies, such as the U.S. Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA), establish safety limits for saxitoxin levels in shellfish. Treatment for saxitoxin poisoning primarily involves supportive care, as there is no specific antidote. Prevention focuses on avoiding consumption of contaminated seafood and adhering to regulatory advisories.