300px, Chemical structure of the ciguatoxin CTX1B
Ciguatoxins are a class of
toxic
Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a sub ...
polycyclic polyether
In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again be ...
s found in fish that cause
ciguatera.
There are several different chemicals in this class. "CTX" is often used as an abbreviation.
* - Ciguatoxin 1
* - Ciguatoxin 2
* - Ciguatoxin 3
* - Ciguatoxin 4B (Gambiertoxin 4b)
Toxic effect on humans
Ciguatoxins do not harm the fish that carry them, but they are poisonous to humans. They cannot be smelled or tasted and cannot be destroyed by cooking.
Rapid testing for this toxin in food is not standard.
Some ciguatoxins lower the threshold for opening excitatory voltage-gated
sodium channel
Sodium channels are integral membrane proteins that form ion channels, conducting sodium ions (Na+) through a cell's membrane. They belong to the superfamily of cation channels and can be classified according to the trigger that opens the chan ...
s in the
nervous system
In biology, the nervous system is the highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body. The nervous system detects environmental changes ...
. Opening a sodium channel causes
depolarization
In biology, depolarization or hypopolarization is a change within a cell, during which the cell undergoes a shift in electric charge distribution, resulting in less negative charge inside the cell compared to the outside. Depolarization is ess ...
, which could sequentially cause paralysis, heart contraction, and changing the senses of heat and cold. Such poisoning from ciguatoxins is known as
ciguatera.
Ciguatoxins are
lipophillic, 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. The
LD50 of ciguatoxin is 0.25 μg/kg.
Bioaccumulation
Ciguatoxin is produced by ''
Gambierdiscus toxicus'', a type of
dinoflagellate
The dinoflagellates ( Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates are ...
. 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
Groupers are fish of any of a number of genera in the subfamily Epinephelinae of the family Serranidae, in the order Perciformes.
Not all serranids are called "groupers"; the family also includes the sea basses. The common name "grouper" ...
,
wrasse
The wrasses are a family, Labridae, of marine fish, many of which are brightly colored. The family is large and diverse, with over 600 species in 81 genera, which are divided into 9 subgroups or tribes.
They are typically small, most of them le ...
,
triggerfish
Triggerfish are about 40 species of often brightly colored fish of the family Balistidae. Often marked by lines and spots, they inhabit tropical and subtropical oceans throughout the world, with the greatest species richness in the Indo-Pacif ...
,
lionfish, and
amberjack. It also affects
barracuda
A barracuda, or cuda for short, is a large, predatory, ray-finned fish known for its fearsome appearance and ferocious behaviour. The barracuda is a saltwater fish of the genus ''Sphyraena'', the only genus in the family Sphyraenidae, which ...
,
snapper,
hogfish
The hogfish (''Lachnolaimus maximus''), also known as boquinete, doncella de pluma or pez perro in Mexico is a species of wrasse native to the Western Atlantic Ocean, living in a range from Nova Scotia, Canada, to northern South America, in ...
,
king mackerel, and
sea bass
Sea bass is a common name for a variety of different species of marine fish. Many fish species of various families have been called sea bass.
In Ireland and the United Kingdom, the fish sold and consumed as sea bass is exclusively the European ...
.
See also
*
Brevetoxin
*
Domoic acid
Domoic acid (DA) is a kainic acid-type neurotoxin that causes amnesic shellfish poisoning (ASP). It is produced by algae and accumulates in shellfish, sardines, and anchovies. When sea lions, otters, cetaceans, humans, and other predators eat c ...
*
Okadaic acid
*
Saxitoxin
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 paralyti ...
*
Tetrodotoxin
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 discovere ...
References
External links
*
{{Toxins
Ion channel toxins
Marine neurotoxins
Phycotoxins
Polyether toxins
Sodium channel openers
Spiro compounds
Non-protein ion channel toxins
