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Ciguatoxins are a class of toxic polycyclic polyethers found in fish that cause ciguatera.
There are several different chemicals in this class. "CTX" is often used as an abbreviation.
Ciguatoxins do not seem to harm the fish that carry them, but they are poisonous to humans. They cannot be smelled or tasted and cannot be destroyed by cooking. [1] Rapid testing for this toxin in food is not standard.
Some ciguatoxins lower the threshold for opening excitatory voltage-gated sodium channels in the nervous system. Opening a sodium channel causes depolarization, which could sequentially cause paralysis, heart arrhythmia, and changing the senses of heat and cold. Such poisoning from ciguatoxins is known as ciguatera.
Ciguatoxins are lipophilic, able to cross the blood–brain barrier, and can cause both central and peripheral neurologic symptoms.
The major symptoms will develop within 1-3 hours of toxin ingestion: vomiting, diarrhea, numbness of extremities, mouth and lips, reversal of hot and cold sensation, muscle and joint aches. The symptoms may last from days to weeks or even months depending on each individual situation. There is no known antidote, though several therapeutic targets have been identified. [2] [3] The LD50 of ciguatoxin in mice is around 200 to 300 ng/kg. [4]
Ciguatoxin is produced by Gambierdiscus toxicus , a type of dinoflagellate. The phenomenon occurs in the Caribbean Sea, Hawaii, and coastal Central America. The toxin usually accumulates in the skin, head, viscera, and roe of big reef fish like grouper, wrasse, triggerfish, lionfish, and amberjack. It also affects barracuda, snapper, hogfish, king mackerel, and sea bass. [5]
In toxicology, the median lethal dose, LD50 (abbreviation for "lethal dose, 50%"), LC50 (lethal concentration, 50%) or LCt50 is a toxic unit that measures the lethal dose of a given substance. The value of LD50 for a substance is the dose required to kill half the members of a tested population after a specified test duration. LD50 figures are frequently used as a general indicator of a substance's acute toxicity. A lower LD50 is indicative of higher toxicity.
Tetrodotoxin (TTX) is a potent neurotoxin. Its name derives from Tetraodontiformes, an order that includes pufferfish, porcupinefish, ocean sunfish, and triggerfish; several of these species carry the toxin. Although tetrodotoxin was discovered in these fish, it is found in several other animals. It is also produced by certain infectious or symbiotic bacteria like Pseudoalteromonas, Pseudomonas, and Vibrio as well as other species found in symbiotic relationships with animals and plants.
The pyrethrins are a class of organic compounds normally derived from Chrysanthemum cinerariifolium that have potent insecticidal activity by targeting the nervous systems of insects. Pyrethrin naturally occurs in chrysanthemum flowers and is often considered an organic insecticide when it is not combined with piperonyl butoxide or other synthetic adjuvants. Their insecticidal and insect-repellent properties have been known and used for thousands of years.
Sodium nitrite is an inorganic compound with the chemical formula NaNO2. It is a white to slightly yellowish crystalline powder that is very soluble in water and is hygroscopic. From an industrial perspective, it is the most important nitrite salt. It is a precursor to a variety of organic compounds, such as pharmaceuticals, dyes, and pesticides, but it is probably best known as a food additive used in processed meats and (in some countries) in fish products.
Ciguatera fish poisoning (CFP), also known simply as ciguatera, is a foodborne illness caused by eating reef fish whose flesh is contaminated with certain toxins called ciguatoxins. Such individual fish are said to be ciguatoxic. Symptoms may include diarrhea, vomiting, numbness, itchiness, sensitivity to hot and cold, dizziness, and weakness. The onset of symptoms varies with the amount of toxin eaten from half an hour to up to two days. The diarrhea may last for up to four days. Some symptoms typically remain for a few weeks to months. Heart difficulties such as slow heart rate and low blood pressure may also occur.
Saxitoxin (STX) is a potent neurotoxin and the best-known paralytic shellfish toxin (PST). Ingestion of saxitoxin by humans, usually by consumption of shellfish contaminated by toxic algal blooms, is responsible for the illness known as paralytic shellfish poisoning (PSP).
Palytoxin, PTX or PLTX is an intense vasoconstrictor, and is considered to be one of the most poisonous non-protein substances known, second only to maitotoxin in terms of toxicity in mice.
Abrin is an extremely toxic toxalbumin found in the seeds of the rosary pea, Abrus precatorius. It has a median lethal dose of 0.7 micrograms per kilogram of body mass when given to mice intravenously. The median toxic dose for humans ranges from 10 to 1000 micrograms per kilogram when ingested and is 3.3 micrograms per kilogram when inhaled.
Many species of fish are caught by humans and consumed as food in virtually all regions around the world. Fish has been an important dietary source of protein and other nutrients throughout human history.
Paralytic shellfish poisoning (PSP) is one of the four recognized syndromes of shellfish poisoning, which share some common features and are primarily associated with bivalve mollusks. These shellfish are filter feeders and accumulate neurotoxins, chiefly saxitoxin, produced by microscopic algae, such as dinoflagellates, diatoms, and cyanobacteria. Dinoflagellates of the genus Alexandrium are the most numerous and widespread saxitoxin producers and are responsible for PSP blooms in subarctic, temperate, and tropical locations. The majority of toxic blooms have been caused by the morphospecies Alexandrium catenella, Alexandrium tamarense, Gonyaulax catenella and Alexandrium fundyense, which together comprise the A. tamarense species complex. In Asia, PSP is mostly associated with the occurrence of the species Pyrodinium bahamense.
Poneratoxin is a paralyzing neurotoxic peptide made by the bullet ant Paraponera clavata. It prevents inactivation of voltage gated sodium channels and therefore blocks synaptic transmission in the central nervous system. Specifically, poneratoxin acts on voltage gated sodium channels in skeletal muscle fibers, causing paralysis, and nociceptive fibers, causing pain. It is rated as a 4 plus on the Schmidt sting pain index, the highest possible rating with that system, and its effects can cause waves of pain up to twelve hours after a single sting. It is additionally being studied for its uses in biological insecticides.
Brevetoxin (PbTx), or brevetoxins, are a suite of cyclic polyether compounds produced naturally by a species of dinoflagellate known as Karenia brevis. Brevetoxins are neurotoxins that bind to voltage-gated sodium channels in nerve cells, leading to disruption of normal neurological processes and causing the illness clinically described as neurotoxic shellfish poisoning (NSP).
Nodularins are potent toxins produced by the cyanobacterium Nodularia spumigena, among others. This aquatic, photosynthetic cyanobacterium forms visible colonies that present as algal blooms in brackish water bodies throughout the world. The late summer blooms of Nodularia spumigena are among the largest cyanobacterial mass occurrences in the world. Cyanobacteria are composed of many toxic substances, most notably of microcystins and nodularins: the two are not easily differentiated. A significant homology of structure and function exists between the two, and microcystins have been studied in greater detail. Because of this, facts from microcystins are often extended to nodularins.
Neurotoxic shellfish poisoning (NSP) is caused by the consumption of brevetoxins, which are marine toxins produced by the dinoflagellate Karenia brevis. These toxins can produce a series of gastrointestinal and neurological effects. Outbreaks of NSP commonly take place following harmful algal bloom (HAB) events, commonly referred to as "Florida red tide". Algal blooms are a naturally-occurring phenomenon, however their frequency has been increasing in recent decades at least in-part due to human activities, climate changes, and the eutrophication of marine waters. HABs have been occurring for all of documented history, evidenced by the Native Americans' understanding of the dangers of shellfish consumption during periods of marine bioluminescence. Blooms have been noted to occur as far north as North Carolina and are commonly seen alongside the widespread death of fish and sea birds. In addition to the effects on human health, the economic impact of HAB-associated shellfish toxin outbreaks can have significant economic implications as well due to not only the associated healthcare costs, but the adverse impact on the commercial shellfish industry.
Gambierdiscus toxicus is a species of photosynthetic unicellular eukaryote belonging to the Alveolata, part of the SAR supergroup. It is a dinoflagellate which can cause the foodborne illness ciguatera, and is known to produce several natural polyethers including ciguatoxin, maitotoxin, gambieric acid, and gambierol. The species was discovered attached to the surface of brown macroalgae.
Neosaxitoxin (NSTX) is included, as other saxitoxin-analogs, in a broad group of natural neurotoxic alkaloids, commonly known as the paralytic shellfish toxins (PSTs). The parent compound of PSTs, saxitoxin (STX), is a tricyclic perhydropurine alkaloid, which can be substituted at various positions, leading to more than 30 naturally occurring STX analogues. All of them are related imidazoline guanidinium derivatives.
Dinotoxins are a group of toxins which are produced by flagellate, aquatic, unicellular protists called dinoflagellates. Dinotoxin was coined by Hardy and Wallace in 2012 as a general term for the variety of toxins produced by dinoflagellates. Dinoflagellates are an enormous group of marine life, with much diversity. With great diversity comes many different toxins, however, there are a few toxins that multiple species have in common.
Profenofos is an organophosphate insecticide. It is a liquid with a pale yellow to amber color and a garlic-like odor. It was first registered in the United States in 1982. As of 2015, it was not approved in the European Union.
Gambierdiscus is a genus of marine dinoflagellates that produce ciguatoxins, a type of toxin that causes the foodborne illness known as ciguatera. They are usually epiphytic on macroalgae growing on coral reefs.
Gambierol is a marine polycyclic ether toxin which is produced by the dinoflagellate Gambierdiscus toxicus. Gambierol is collected from the sea at the Rangiroa Peninsula in French Polynesia. The toxins are accumulated in fish through the food chain and can therefore cause human intoxication. The symptoms of the toxicity resemble those of ciguatoxins, which are extremely potent neurotoxins that bind to voltage-sensitive sodium channels and alter their function. These ciguatoxins cause ciguatera fish poisoning. Because of the resemblance, there is a possibility that gambierol is also responsible for ciguatera fish poisoning. Because the natural source of gambierol is limited, biological studies are hampered. Therefore, chemical synthesis is required.
