Cantharidin Poisoning

Covalent Binding of Reactive Anhydride of Cantharidin to Biological Amines

Cantharidin is a terpenoid from coleoptera beetles. Cantharidin has been used to treat molluscum contagiosum and some types of tumors. Cantharidin is highly toxic, and cantharidin poisoning and fatal cases have been reported worldwide. The mechanisms underlying cantharidin-induced toxicity remain unclear. Cantharidin contains anhydride, which may react with biologic amines. This study aimed to examine the chemical reactivity of cantharidin toward nucleophiles and characterize adducts of cantharidin with biologic amines in vitro and in mice. Here two types of conjugates were formed in the incubation of cantharidin under physiologic conditions with free amino acids, a mimic peptide, or amine-containing compounds, respectively. Amide-type conjugates were produced by the binding of cantharidin anhydride with the primary amino group of biologic amines. Imide-type conjugates were generated from the dehydration and cyclization of amide-type conjugates. The structure of the conjugates was characterized by using high-resolution mass spectrometry. We introduced the 14N/15N and 79Br/81Br isotope signatures to confirm the formation of conjugates using L-(ε)15N-lysine, L-lysine-15N2, and bromine-tagged hydrazine, respectively. The structure of imide conjugate was also confirmed by nuclear magnetic resonance experiments. Furthermore, the amide and imide conjugates of cantharidin with amino acids or N-acetyl-lysine were detected in mouse liver and urine. Cantharidin was found to modify lysine residue proteins in mouse liver. Pan-cytochrome P450 inhibitor 1-aminobenzotriazole significantly increased the urine cantharidin-N-acetyl-lysine conjugates, whereas it decreased cantharidin metabolites. In summary, cantharidin anhydride can covalently bind to biologic amines nonenzymatically, which facilitates a better understanding of the role of nonenzymatic reactivity in cantharidin poisoning. SIGNIFICANCE STATEMENT: Anhydride moiety of cantharidin can covalently bind to the primary amino group of biological amines nonenzymatically. Amide and imide conjugates were generated after the covalent binding of cantharidin anhydride with the primary amino groups of amino acids, a mimic peptide, and protein lysine residues. The structure of conjugates was confirmed by 14N/15N and 79Br/81Br isotope signatures using isotope-tagged reagents and nuclear magnetic resonance experiments. This study will facilitate the understanding of the role of nonenzymatic reactivity in cantharidin poisoning.

Avian Toxins and Poisoning Mechanisms

All around the world, there are species of birds that have developed the ability to acquire toxic chemicals in their bodies making them less palatable or even lethal when consumed or contacted. Exposure to poisonous bird species is rare among humans, yet their poisons can produce serious clinical outcomes. In this study, we conducted a literature search focusing on seven avian species: the pitohuis (Pitohui spp.), blue-capped ifrita (Ifrita kowaldi), European quail (Cortunix corturnix coturnix), spur or spoor-winged goose (Plectropterus gambensis), North American ruffed grouse (Bonasa umbellus), Brush bronzewings (Phaps elegans), and European hoopoes and woodhoopoes (Upupa epops and Phoeniculus purpureus, respectively). We present the geographic distribution of each poisonous bird, toxin physiology and origin, clinical signs and symptoms of poisoning, cases of human toxicity if available and discuss the birds' ability to prevent self-intoxication. Our results suggest that most cases of contact with toxic birds produce mild symptoms as most of these birds apart from the European quail (C. c. corturnix) and North American ruffed grouse (B. umbellus) are not commonly consumed by humans. Furthermore, we discuss several methods of toxin acquisition in these bird species, which are mostly diet acquired apart from the hoopoes and woodhoopoes (Upupa and Phoeniculus spp.) who have a symbiotic relationship with chemical-producing bacteria in their uropygial glands. In summary, our study provides a comprehensive review of the toxic physiology, clinical manifestations, and evolutionary insight to avian toxins.

Acute kidney injury by cantharidin poisoning following a silly bet on an ugly beetle

Cantharidin is a poisonous substance secreted by blister beetles, including the ‘Spanish fly’. Historically, cantharidin was used as an aphrodisiac, vesicant and abortifacient. Symptoms of poisoning include gastrointestinal and genitourinary mucosal irritation along with renal dysfunction. We present the case of a reckless 23-year-old soldier who accepted the challenge of eating a beetle (Berberomeloe majalis). Six hours later he was admitted to the emergency room with abdominal pain, dysuria, gross haematuria with clots, hypotension, fever and renal insufficiency. With intravenous fluid therapy, he recovered clinically. Laboratory parameters returned to normal within 1 week.

Pharmacological properties of blister beetles (Coleoptera: Meloidae) promoted their integration into the cultural heritage of native rural Spain as inferred by vernacular names diversity, traditions, and mitochondrial DNA

ETHNOPHARMACOLOGICAL RELEVANCE

Beetles of the family Meloidae (blister beetles) are often reported in pharmacological literature because of their content of cantharidin. Cantharidin has a long history in human medicine and was commonly applied in the 19th and the early 20th centuries, although its use has been progressively abandoned since then. Contrary to most, even common, large species of Coleoptera, blister beetles of the genera Berberomeloe, Physomeloe and to a lesser extent Meloe, are usually recognized and often incorporated into local folk taxonomy by inhabitants of rural areas in Spain.

AIM OF THE STUDY

To demonstrate the role that pharmacological properties of blister beetles must have played in their integration in the culture of early Iberian human societies, but also in the preservation of their identity until today, a rare case for Spanish insects. To achieve this purpose we document the diversity of vernacular names applied in rural areas of Spain, and we determine, using molecular data, the antiquity of the presence of two species of the better-known blister beetle in rural Spain, Berberomeloe majalis and Berberomeloe insignis.

MATERIALS AND METHODS

We try to document the extent of traditional knowledge of meloid beetles in rural areas by interviewing about 120 people from villages in central and southern Spain. We also use mitochondrial DNA sequences (Cytochrome Oxidase I and 16SrRNA) obtained from several populations of two species of the better known blister beetle in rural Spain, Berberomeloe majalis and Berberomeloe insignis, to determine whether these beetles were already present in the Iberian Peninsula when earlier ancient cultures were developing.

RESULTS

Our results show that, based on mitochondrial DNA, blister beetles of the genus Berberomeloe were present in the Iberian Peninsula long before humans arrived, so ancient Iberian cultures were in contact with the same beetle species occurring now in rural areas. On the other hand, people interviewed in rural communities provided us with more than 28 different vernacular names, a few short songs incorporated to local folklore, and some therapeutic uses.

CONCLUSIONS

Current knowledge of blister beetles of the family Meloidae in rural Spain was likely developed as a consequence of their pharmacological properties; we hypothesize this knowledge was inherited from ancient pre-Christian Iberian native cultures as part of their traditional therapeutic traditions. It is possible then, that current vernacular names and traditional songs are the only remnants of an ancient knowledge of pharmacological uses of meloid beetles, verbally transmitted from the ancestral cultures to modern day rural Spain. Our work suggests that this legacy, part of the European Cultural Heritage, is disappearing fast, in parallel to the loss of traditional agricultural techniques.

Oral bioavailability of cantharidin-loaded solid lipid nanoparticles

BACKGROUND

The clinical application of cantharidin (CA) is limited by its insolubility, toxicity and short half-life in circulation. This study aims to achieve a steady and sustained blood concentration-time profile, using solid lipid nanoparticles (SLNs) as a drug carrier.

METHODS

CA-SLNs were prepared by a film dispersion-ultrasonication method. The physiochemical properties were studied by transmission electron microscopy. In vitro release and in vivo evaluation of CA-SLNs were studied by GC and GC-MS, while a comparison of the pharmacokinetic properties between CA-SLNs and free CA was performed in rats.

RESULTS

The mean size, drug content and encapsulation yield of CA-SLNs were 121 nm, 13.28 ± 0.12% and 93.83 ± 0.45%, respectively. The results show that CA-SLNs had a sustained release profile without a burst effect, a higher bioavailability than free CA after oral administration, and that the relative bioavailability of CA-SLNs to free CA was 250.8%.

CONCLUSION

CA-SLNs could improve the solubility and oral bioavailability of CA.

Poisoning from "Spanish fly" (cantharidin)

Cantharidin, known popularly as Spanish fly, has been used for millennia as a sexual stimulant. The chemical is derived from blister beetles and is notable for its vesicant properties. 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. Priapism, seizures, and cardiac abnormalities are less commonly seen. We report four cases of cantharidin poisoning presenting to our emergency department with complaints of dysuria and dark urine. Three patients had abdominal pain, one had flank pain, and the one woman had vaginal bleeding. Three had hematuria and two had occult rectal bleeding. Low-grade disseminated intravascular coagulation, not previously associated with cantharidin poisoning, was noted in two patients. Management of cantharidin poisoning is supportive. Given the widespread availability of Spanish fly, its reputation as an aphrodisiac, and the fact that ingestion is frequently unwitting, cantharidin poisoning may be a more common cause of morbidity than is generally recognized. Cantharidin poisoning should be suspected in any patient presenting with unexplained hematuria or with GI hemorrhage associated with diffuse injury of the upper GI tract.

A fatal case of poisoning with cantharidin

A case of fatal poisoning due to voluntary ingestion of cantharides powder for aphrodisiac purposes is reported. Clinical history, autopsy and analytical findings are described. Blood and urine samples collected during the 30 h of survival, as well as the cantharides product, were analyzed by gas chromatography-mass spectrometry. On the basis of the percentage of the active principle measured in the powder, an ingested dose of 26-45 mg of cantharidin could be estimated.

Pathological features of cantharidin-induced toxic cardiomyopathy: lack of correlation between electron-microscopic and histopathologic myocardial damage

Electron-microscopic evidence of the cardiotoxic effects of cantharidin administered to rabbits was observed. No correlation was found between the electron-microscopic changes and the light-microscopic features as assessed by special histological stains. The reasons for this are discussed.

Pathology of blister beetle (Epicauta) poisoning in horses

Case records of 21 horses that had acute illness after eating baled alfalfa hay containing dead striped blister beetles were reviewed. Tissue sections from 14 of the horses were examined; sections from two normal horses and several others with unrelated diseases were used for comparison.

Clinical illness was characterized by abdominal pain, fever, depression, frequent urination, shock and, occasionally, synchronous diaphragmatic flutter. Laboratory findings were hemoconcentration, neutrophilic leukocytosis, hypocalcemia, hematuria and low urine specific gravity. Major morphologic changes were sloughing of the stratified squamous epithelium of the stomach, hemorrhage and ulceration in the urinary bladder, enterocolitis and myocardial necrosis. Five horses with experimental poisoning had lesions and clinical signs similar to those of the natural disease.

Acute disturbance of both the gastrointestinal and urinary tracts, and the stomach and bladder lesions, were regarded as sufficiently suggestive of blister beetle poisoning to be useful in differential diagnosis, but no pathognomonic lesions were found. Therefore, striped blister beetles should be sought in hay fed to affected horses if blister beetle poisoning is suspected.