Saxitoxines

Saxitoxines are a class of potent neurotoxins known for their ability to inhibit nerve signal transmission. These toxins belong to the paralytic shellfish toxins group and are produced primarily by certain species of dinoflagellates, such as Alexandrium, Gymnodinium, and Pyrodinium, which can accumulate in marine organisms like shellfish and finfish.

Chemically, saxitoxines are characterized by a complex and highly water-soluble structure that enables them to block sodium channels in nerve cells. By binding to voltage-gated sodium channels on nerve cell membranes, they prevent the initiation and propagation of action potentials. This mechanism results in paralysis of affected organisms and manifests in humans as a potentially life-threatening condition known as paralytic shellfish poisoning (PSP).

Human exposure typically occurs through the consumption of contaminated shellfish during algal blooms, often called red tides. Symptoms of PSP include numbness, tingling, muscular weakness, dizziness, and in severe cases, respiratory failure. The onset of symptoms generally appears within a few minutes to a few hours after ingestion.

Due to their high potency, saxitoxines are subjects of concern for public health authorities, prompting monitoring of shellfish harvesting areas. No specific antidote exists for saxitoxin poisoning; treatment primarily involves supportive care, including respiratory support until the toxin is eliminated from the body.

Research on saxitoxines extends to their potential applications in neuroscience as tools for studying nerve function and as models for developing novel pharmaceuticals. Their role in natural ecosystems is also studied to understand biogeochemical interactions in marine environments.