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Names | |
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Preferred IUPAC name (3aR,4S,7R,7aS)-3a,7a-Dimethylhexahydro-4,7-epoxy[2]benzofuran-1,3-dione | |
Other names
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Identifiers | |
3D model (JSmol) | |
85302 | |
ChEBI | |
ChEMBL | |
ChemSpider | |
ECHA InfoCard | 100.000.240 |
EC Number |
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KEGG | |
PubChem CID | |
UNII | |
CompTox Dashboard (EPA) | |
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Properties | |
C10H12O4 | |
Molar mass | 196.202 g·mol−1 |
Density | 1.41 g/cm3 |
Melting point | 212 °C (414 °F; 485 K) |
Pharmacology | |
None | |
Topical | |
Legal status | |
Hazards | |
Occupational safety and health (OHS/OSH): | |
Main hazards | Highly toxic |
GHS labelling: | |
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Danger | |
H300, H315, H319, H335 | |
P261, P264, P270, P271, P280, P301+P310, P302+P352, P304+P340, P305+P351+P338, P312, P321, P330, P332+P313, P337+P313, P362, P403+P233, P405, P501 | |
NFPA 704 (fire diamond) | |
Lethal dose or concentration (LD, LC): | |
LD50 (median dose) | 0.03–0.5 mg/kg (human) |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Clinical data | |
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Trade names | Ycanth, others |
License data |
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Routes of administration | Topical |
Legal status | |
Legal status |
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Identifiers | |
DrugBank | |
CompTox Dashboard (EPA) | |
ECHA InfoCard | 100.000.240 |
Chemical and physical data | |
Formula | C10H12O4 |
Molar mass | 196.202 g·mol−1 |
Cantharidin is an odorless, colorless fatty substance of the terpenoid class, which is secreted by many species of blister beetles. [a] Its main current use in pharmacology is treating molluscum contagiosum and warts topically. [2] It is a burn agent and poisonous in large doses, and has been historically used as aphrodisiacs (Spanish fly). In its natural form, cantharidin is secreted by the male blister beetle, and given to the female as a copulatory gift during mating. Afterwards, the female beetle covers her eggs with it as a defense against predators.
Poisoning from cantharidin is a significant veterinary concern, especially in horses, but it can also be poisonous to humans if taken internally (where the source is usually experimental self-exposure). Externally, cantharidin is a potent vesicant (blistering agent), exposure to which can cause severe chemical burns. Properly dosed and applied, the same properties have also been used therapeutically, for instance, for treatment of skin conditions, such as molluscum contagiosum infection of the skin.
Cantharidin is classified as an extremely hazardous substance in the United States, and is subject to strict reporting requirements by facilities that produce, store, or use it in significant quantities. [3]
Cantharidin, from the Greek kantharis, for beetle, [4] is an odorless, colorless natural product with solubility in various organic solvents,[ specify ] but only slight solubility in water. [5] Its skeleton is tricyclic, formally, a tricyclo-[5.2.1.02,6]decane skeleton. Its functionalities include a carboxylic acid anhydride (−CO−O−CO−) substructure in one of its rings, as well as a bridging ether in its bicyclic ring system.
The complete mechanism of the biosynthesis of cantharidin is unknown. Its framework formally consists of two isoprene units. [6] However, feeding studies indicate that the biosynthetic process is more complicated, and not a simple product of geranyl pyrophosphate or related ten-carbon parent structure, as the seeming monoterpene nature would suggest. Instead, there is a farnesol (15-carbon) precursor from which certain carbon segments are later excised. [7]
The level of cantharidin in blister beetles can be quite variable. Among blister beetles of the genus Epicauta in Colorado, E. pennsylvanica contains about 0.2 mg, E. maculata contains 0.7 mg, and E. immaculata contains 4.8 mg per beetle; males also contain higher levels than females. [8]
Males of Berberomeloe majalis have higher level of cantharidin per beetle: 64.22 ± 51.28 mg/g (dry weight) and 9.10 ± 12.64 mg/g (d. w.). Cantharidin content in haemolymph is also higher in males (80.9 ± 106.5 μg/g) than in females (20.0 ± 41.5 μg/g). [9]
Preparations made from blister beetles (particularly "Spanish fly") have been used since ancient times as an aphrodisiac, possibly because their physical effects were perceived to mimic those of sexual arousal, [10] and because they can cause prolonged erection or priapism in men. [11] These preparations were known as cantharides, from the Greek word for "beetle".
Examples of such use found in historical sources include:
Cantharidin was first isolated as a chemically pure substance in 1810 by Pierre Robiquet, [23] a French chemist then living in Paris. Robiquet isolated cantharidin as the active ingredient in pharmacological preparations of Lytta vesicatoria , a.k.a. "Spanish fly", a species of blister beetle. This was one of the first historical instances of the identification and extraction of a simple active principle from a complex medicine.
Robiquet found cantharidin to be an odorless and colorless solid at room temperature. He demonstrated that it was the active principle responsible for the aggressively blistering properties of the coating of the eggs of the blister beetle, and additionally established that cantharidin had toxic properties comparable in degree to those of the most virulent poisons known in the 19th century, such as strychnine. [24]
Poisoning by Epicauta species from cantharidin is a significant veterinary concern, especially in horses; species infesting feedstocks depend on region—e.g., Epicauta pennsylvanica (black blister beetle) in the U.S. midwest; and E. occidentalis, temexia, and vittata species (striped blister beetles) in the U.S. southwest—where the concentrations of the agent in each can vary substantially. [5] Beetles feed on weeds, and occasionally move into crop fields used to produce livestock feeds (e.g., alfalfa), where they are found to cluster and find their way into baled hay, e.g., a single flake (4–5 in. section [29] ) may have several hundred insects, or none at all. [5] Horses are very sensitive to the cantharidin produced by beetle infestations: the LD50 for horses is roughly 1 mg/kg of the horse's body weight. Horses may be accidentally poisoned when fed bales of fodder with blister beetles in them. [30]
Great bustards, a strongly polygynous bird species, [31] are not immune to the toxicity of cantharidin; they become intoxicated after ingesting blister beetles. However, cantharidin has activity also against parasites that infect them. [32] [33] Great bustards may eat toxic blister beetles of the genus Meloe to increase the sexual arousal of males. [34]
As a blister agent, cantharidin has the potential to cause adverse effects when used medically; for this reason, it has been included in a list of "problem drugs" used by dermatologists and emergency personnel. [35] However, this references unregulated sources of cantharidin. [36] In July 2023, the US FDA approved a topical formulation of cantharidin (Ycanth) for the treatment of molluscum contagiosum. [37]
When ingested by humans, the LD50 is unknown, but fatal doses have been recorded between 10 mg and 65 mg. [38] The median lethal dose appears to be around 1 mg/kg [39] but individuals have survived after consuming oral doses as high as 175 mg. [40] Ingesting cantharidin can initially cause severe damage to the lining of the gastrointestinal and urinary tracts, and may also cause permanent renal damage. Symptoms of cantharidin poisoning include blood in the urine, abdominal pain, and (rarely) prolonged erections. [36]
The extreme toxicity of cantharidin makes any use as an aphrodisiac highly dangerous. [41] [42] As a result, it is illegal to sell (or use) cantharidin or preparations containing it without a prescription in many countries. [35]
This section is missing information about toxicological mechanism when ingested.(September 2022) |
Topical cantharidin is absorbed by the lipid membranes of epidermal cells, causing the release of serine proteases, enzymes that break the peptide bonds in proteins. This causes the disintegration of desmosomal plaques, cellular structures involved in cell-to-cell adhesion, leading to detachment of the tonofilaments that hold cells together. The process leads to the loss of cellular connections (acantholysis), and ultimately results in blistering of the skin. Lesions heal without scarring. [43] [44]
VP-102, an experimental drug-device combination that includes cantharidin delivered via a single-use applicator, was studied for the treatment of molluscum contagiosum, common warts, and genital warts. [45] . The efficacy of cantharidin was formally established for the treatment of molluscum in patients 2 years and older in two double-blind, randomized, placebo-controlled trials. It is now FDA-approved for the treatment of molluscum contagiousum under the brand name Ycanth and is marketed by Verrica Pharmaceuticals. [46]
Cantharidin appears to have some effect in the topical treatment of cutaneous leishmaniasis in animal models. [47] In addition to topical medical applications, cantharidin and its analogues may have activity against cancer cells. [48] [49] [50] Laboratory studies with cultured tumor cells suggest that this activity may be the result of PP2A inhibition. [51] [52]
While most commonly available preparations of Spanish fly contain cantharidin in negligible amounts, if at all, the chemical is available illicitly in concentrations capable of causing severe toxicity. Symptoms of cantharidin poisoning include burning of the mouth, dysphagia, nausea, hematemesis, gross hematuria, and dysuria. Mucosal erosion and hemorrhage is seen in the upper gastrointestinal (GI) tract. Renal dysfunction is common and related to acute tubular necrosis and glomerular destruction.
Cantharidin ("Spanish fly") is a chemical with vesicant properties derived from blister beetles, which has been used for millennia as a sexual stimulant by both sexes. Its mode of action is by inhibition of phosphodiesterase and protein phosphatase activity and stimulation of β-receptors, inducing vascular congestion and inflammation. Morbidity from its abuse is significant. The gastrointestinal tract sustains the brunt of toxicity, resulting in fatal hemorrhages. Renal toxicity is a result of its renal excretion, which may lead to acute tubular necrosis. Cardiac effects are most likely due to hemorrhagic shock, but they also can be due to myofibril degeneration, mitochondrial swelling, and pericardial and subendocardial hemorrhages.
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