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Bufotoxin
Bufotoxin
Bufotoxin
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Bufotoxins are a family of toxic steroid lactones or substituted tryptamines of which some are toxic. They occur in the parotoid glands, skin, and poison of many toads (Bufonidae family) and other amphibians, and in some plants and mushrooms.[1][2][3] The exact composition varies greatly with the specific source of the toxin.

Composition

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Chemical structure of one of the main components of bufotoxin, a conjugate of bufagin with suberylarginine. This component is itself sometimes called bufotoxin.

Bufotoxins can contain 5-MeO-DMT, bufagins, bufalin, bufotalin, bufotenin, bufothionine, dehydrobufotenine, epinephrine, norepinephrine, and serotonin. Some authors have also used the term bufotoxin to describe the conjugate of a bufagin with suberylarginine.[4]

The toxic substances found in toads can be divided by chemical structure in two groups:

  1. bufadienolides, which are cardiac glycosides (e.g., bufotalin, bufogenin), are compounds that may be fatal if consumed.
  2. tryptamine-related substances (e.g., bufotenin), are sought after for entheogenic and/or recreational purposes by some individuals. However, the practice of using these substances derived from animals for spiritual experiences or responsible drug use may raise ethical concerns about the potential suffering inflicted on the animal.

Species

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See also: List of poisonous animals

Toads known to secrete bufotoxins.[5]

Toads frequently "milked"

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Despite being a frequent target for milking, these toads still carry cardiotoxic bufotoxins which have been linked to deaths.

Other toads

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The effects of the bufotoxins in these toads are not well understood.

Extraction

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Extract from the skin of certain Asian toads, such as Bufo bufo gargarizans and Bufo melanostictus, is often found in certain Chinese folk remedies. The Pharmacopoeia of the People's Republic of China (ChP) considers the two species valid sources of toad poison (Chinese: 蟾酥; pinyin: Chánsū; Latin: bufonis venenum), and requires the dry product to contain at least 6% of cinobufagin and resibufogenin combined by weight. The extract is obtained by squeezing the parotoid glands of caught, washed toads for a white venom and drying; the final dried poison is usually brown, with a chunk or flake form.[6]

Human poisoning

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Poisoning from toad toxin is rare but can kill.[7] It can occur when someone drinks toad soup, eats toad meat or toad eggs, or swallows live toads.[7][8] It can also happen when someone deliberately takes commercial substances made with toad toxins.[8] These go under names including "Kyushin", "Chan Su" (marketed as a painkiller,[8] topical anesthetic, or cardiac treatment[9]), "Rockhard", and "Love Stone" (marketed as aphrodisiacs).[8]

"Chan Su" (literally "toad venom") is often adulterated with standard painkillers, such as paracetamol, promethazine, and diclofenac. It may be ingested or injected.[10]

Symptoms of intoxication

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Symptoms may vary depending on certain factors such as the size and age of the victim. Other than the first, more benign symptoms (such as a tingling or burning sensation in the eyes, mucous membranes, or in exposed wounds), the most frequently described symptoms in the medical literature are:

One epileptic episode caused by bufotoxins was observed in a five-year-old child, minutes after they had placed a Bufo alvarius in their mouth. The child was successfully treated with diazepam and phenobarbital.[11]

In extreme cases following ingestion of mucus or skin of the toad, death generally occurs within 6 and 24 hours. Victims surviving past 24 hours generally will recover.

References

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Bufotoxin

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Bufotoxin is a toxic , specifically exemplified by the bufotalin 3-suberoyl ester with molecular formula C40H60N4O10, secreted in the parotoid glands, , and of toads primarily in the genus and certain other amphibians. These compounds, which also occur in some and mushrooms, function as cardiac glycosides by inhibiting the sodium- , resulting in elevated intracellular sodium and calcium levels, extracellular potassium accumulation, and disruptions in cardiac rhythm that can lead to , arrhythmias, and death. Bufotoxins represent conjugated forms of bufadienolides—steroid-like aglycones—with suberic acid and arginine, distinguishing them from the free bufogenins in toad secretions, and their composition varies across toad , contributing to the venom's overall pharmacological profile. While acutely poisonous and responsible for intoxications from toad handling or ingestion, bufadienolide-derived bufotoxins have demonstrated antiproliferative effects against cancer cells at sublethal doses, prompting research into their potential medicinal uses despite toxicity risks.

History and Discovery

Early Uses and Observations

Ancient Roman naturalist , in his composed around 77 AD, described toads as carriers of potent poisons, attributing to them properties such as a from the right side that could prevent from or neutralize toxins when introduced. These observations reflected early empirical recognition of toad secretions' toxicity, often linked to defensive glandular excretions, though intertwined with about magical antidotal effects. In medieval , from roughly the 5th to 15th centuries, the ( species) was dualistically viewed: celebrated in some medical texts as a source of panaceas derived from its for treating ailments like sores and , while simultaneously persecuted as a symbol of diabolical used in and assassinations by applying secretions to skin or wounds. European physicians incorporated dried and powdered toad into early , leveraging its cardiotoxic effects akin to , despite risks of lethality from improper dosing. In , toad venom collection dates to the (618–907 CE), where secretions from bufo gargarizans were processed into Chansu for applications against pain, swelling, carbuncles, and respiratory issues; similar uses appeared in Japanese Senso preparations during the same era. Mesoamerican indigenous groups, predating European contact, employed Bufo marinus or Incilius alvarius secretions as hallucinogens, either by direct skin contact or smoked powders, indicating early recognition of psychoactive components within the venom. These practices, though empirically observed for therapeutic or ritual effects, often disregarded the venom's variable toxicity and lacked purification, leading to documented poisonings.

Scientific Isolation and Characterization

Bufotoxin was first isolated in crystalline form by German chemist Heinrich Wieland and his collaborator Richard Alles in 1922 from the parotoid gland secretions of the common European , Bufo vulgaris. The process involved extracting the dried with , followed by purification steps including dissolution in , precipitation, and recrystallization, yielding a compound with digitalis-like cardiotoxic effects and a melting point around 198–200°C. This marked the initial scientific separation of bufotoxin as a distinct entity from the crude toad , previously known in traditional medicines like Ch'an Su. Early characterization relied on classical organic analytical techniques, including acid and enzymatic , which decomposed bufotoxin into its components: the aglycone bufotalin (a with formula C₂₆H₃₄O₆), suberic acid (octanedioic acid), and . Wieland's group established that bufotoxin is the formed between the 3-hydroxyl of bufotalin and the carboxyl of suberoylarginine, distinguishing it from simpler bufogenins. The full molecular formula, C₄₀H₆₀N₄O₁₀, was confirmed through and degradation studies completed by Wieland's team circa 1942, two decades after isolation. Subsequent refinements in the mid-20th century, prior to widespread use of spectroscopic methods, involved comparative pharmacology and further degradations, revealing bufotoxin's structural similarity to plant cardenolides but with a characteristic α-pyrone ring in the bufadienolide core. These efforts underscored bufotoxin's role as a conjugated toxin, with the arginine-suberate moiety enhancing solubility and possibly bioavailability in defense secretions. Isolation yields from B. vulgaris were low, typically 0.5–1% of dried venom by weight, prompting later researchers to explore variants in other Bufo species using improved chromatographic techniques.

Chemical Composition

Core Structures: Bufadienolides

Bufadienolides constitute the core steroidal aglycones of bufotoxins, comprising a C24 skeleton with a characteristic six-membered α,β-unsaturated ring (2-pyrone) fused at the 17β position. This structural feature differentiates from cardenolides, which feature a five-membered γ-butenolide ring, and confers potent inhibition of Na+/K+-ATPase, underlying their cardiotoxic effects. The nucleus typically exhibits trans fusions between B/C and C/D rings, with A/B cis or trans configurations, and includes a Δ^4 , often a 3β-hydroxy or 3-keto group, and additional unsaturations such as Δ^5,6 or Δ^14,15. Hydroxyl groups commonly occur at positions 1β, 5β, 11α, 12β, 14β, and 16β, with possible acetyl, epoxy, or formyl substitutions enhancing structural diversity. Over 75 free s have been identified from sources, including prototypes like bufalin (3β,14-dihydroxybufa-4,20,22-trienolide) and cinobufagin (3β-acetoxy-5,14-dihydroxybufa-4,20,22-trienolide). In bufotoxins, the core is conjugated at the 3-position, typically via esterification of the 3β-hydroxyl with dicarboxylic acids (e.g., hemisuberate) or sulfates, often further linked to such as , yielding polar derivatives that improve solubility and . These conjugated forms, termed bufotoxins proper, retain the cardiotoxic scaffold while modulating , with examples including bufotalin conjugates identified in species venoms.

Conjugated Forms and Variants

Bufotoxins encompass the conjugated derivatives of bufadienolide aglycones, where the 3β-hydroxyl group of the core steroid structure is esterified with dicarboxylic acids or their amide-linked amino acid extensions, enhancing solubility and potentially modulating toxicity. The archetypal conjugation involves suberic acid (a C8 dicarboxylic acid) forming hemisuberate esters or, more commonly, suberoyl-linked arginine, yielding water-soluble bufotoxins such as the bufotalin 3-suberoylarginine ester (molecular formula C₄₀H₆₀N₄O₁₀). This arginine conjugate, often termed regularobufotoxin, exemplifies the structure in common toad (Bufo bufo) venom, where the suberoyl chain bridges the bufadienolide to the guanidino group of L-arginine via an amide bond. Variants arise from differences in the aglycone core or the conjugating moiety. Core aglycones include bufalin (14,16β-epoxy-3β,5,14-trihydroxycard-20(22)-enolide), cinobufagin, and cinobufotalin, each yielding distinct bufotoxins like cinobufotalin-3-suberoyl, predominant in the venom of gargarizans. Alternative conjugations feature sulfate groups at C-3 (e.g., 3-sulfates), other dicarboxylic acids (up to 17 reported types linked to ), or instead of , as in suberoylglycine esters. These modifications vary by toad and tissue; for instance, skin secretions of Rhinella marina yield primarily hemisuberate and diacid- conjugates. Recent analyses have identified additional variants, including bufadienolide-fatty acid conjugates in fertilized eggs of gargarizans, where 30 such compounds—25 novel—link the aglycone to saturated or unsaturated fatty acids like palmitic or via bonds, potentially serving developmental or defensive roles distinct from bufotoxins. Comprehensive profiling across species reveals over 126 bufadienolide-related compounds, with conjugates comprising free esters, indole-linked forms, and hybrids, underscoring structural diversity tied to ecological pressures. Such variants exhibit conserved Na⁺/K⁺-ATPase inhibitory potency but differ in and metabolic stability due to conjugation type.

Biological Sources

Primary Species Producing Bufotoxins

Bufotoxins are primarily secreted by true toads of the family Bufonidae, an group comprising over 600 distributed worldwide, with the toxins concentrated in parotoid glands, skin, and ocular secretions as a against predators. These compounds, which include steroids conjugated with suberic acid or related chains, vary in composition and potency across , but production is characteristic of most bufonids, enabling empirical identification through bioassays showing cardiotoxic effects akin to . The (Rhinella marina, syn. Bufo marinus), native to South and but introduced to and elsewhere, is among the most prolific producers, yielding parotoid secretions rich in marinobufagin (up to 0.2% dry weight) alongside bufalin and other bufadienolides, with toxicity levels sufficient to kill predators like dogs upon oral exposure (LD50 ~0.2 mg/kg in mice for crude venom). Similarly, the (Incilius alvarius, syn. Bufo alvarius) secretes potent bufotoxins from parotoid glands, including psychoactive precursors, rendering it highly toxic to mammals and responsible for veterinary intoxications in the . In Eurasia, the common toad (Bufo bufo) and its close relatives, such as the Asiatic toad (Bufo gargarizans) and black-spotted toad (Bufo melanostictus), are primary sources, with dried venom (known as Ch'an Su in traditional Chinese medicine) containing cinobufagin and resibufogenin at concentrations up to 10% of secretion mass, as quantified in proteomic analyses of parotoid extracts. These species exhibit consistent bufotoxin profiles across populations, though quantities fluctuate seasonally and with habitat stress, as evidenced by gland size increases in urban environments. North American species like the American toad (Anaxyrus americanus, syn. Bufo americanus) produce milder bufotoxins primarily for deterrence, with secretions irritating to mucous membranes but less cardiotoxic than those of invasive congeners. Overall, while all bufonids synthesize bufadienolide precursors, interspecies variation in conjugation and expression—driven by genetic and environmental factors—determines clinical potency, with Rhinella and Bufo genera dominating pharmacological studies due to extractable yields exceeding 1 mg/g gland tissue.

Geographic Distribution and Species Variations

Bufotoxins are secreted by species primarily within the family Bufonidae, with the genus Bufo and related taxa such as Rhinella serving as key producers; these amphibians are distributed across the , , and parts of , though toxin-producing capacity is most pronounced in certain lineages native to subtropical and temperate zones. The cane toad (Rhinella marina, formerly Bufo marinus) exemplifies widespread Neotropical origins, with a native range extending from southern through to the and southeastern , where populations exhibit robust parotoid gland secretions rich in bufadienolides. This species has been introduced to regions including , the , the , , , and parts of the (e.g., , ), facilitating broader geographic exposure to its toxins, though native distributions correlate with higher baseline toxin diversity. In , species like the Asian toad (Bufo gargarizans) predominate in eastern, southwestern, and , where environmental factors such as influence profiles, including concentrations adapted to local predators. European common toads (Bufo bufo) occupy much of (excluding ) and extend into western , producing bufotoxins in skin and glandular secretions that vary seasonally and geographically within populations. North American representatives, such as the (Incilius alvarius, formerly Bufo alvarius), are confined to the and , contributing to regional incidents due to potent yields. Japanese taxa, including Bufo japonicus forms, show localized distributions in with parotoid secretions tailored to endemic threats. Species variations in bufotoxin composition arise from differences in bufadienolide types, conjugation patterns, and concentrations, reflecting genetic and ecological adaptations; for example, all Bufo species synthesize these steroids, but Rhinella marina yields higher quantities of cardiotoxic variants compared to Eurasian congeners. Analyses of Chinese Bufo species (B. gargarizans, B. andrewsi, and others) reveal over 126 compounds, including free and conjugated bufadienolides alongside indole alkaloids, with interspecific profiles differing in hydroxylation and side-chain modifications that modulate potency. Neotropical bufoid venoms, such as those from Rhinella species, exhibit greater chemical diversity in bufadienolide glycosides, potentially linked to predator pressures in humid tropics, whereas temperate species prioritize fewer, more stable congeners for storage efficiency. These disparities underscore how toxin formulations evolve regionally, with urban-rural gradients further modulating concentrations (e.g., reduced bufotoxin levels in urban Bufo due to altered diets or stressors).
Species/TaxonNative RangeKey Toxin Variation Notes
Rhinella marinaCentral/South America (Texas to Peru/Amazon)Elevated bufadienolide quantities; diverse glycosides for broad-spectrum defense.
Bufo gargarizansEastern/southwestern/central ChinaHigh indole alkaloid co-occurrence; climate-influenced bufadienolide hydroxylation.
Bufo bufo to western Moderate concentrations; stable congeners suited to temperate predators.
Incilius alvariusSouthwestern US/northern MexicoPotent 5-methoxy-DMT admixtures with bufadienolides, enhancing .
Japanese Bufo taxa (e.g., B. japonicus) ()Taxon-specific bufadienolide ratios in parotoid glands, varying by locality.

Biosynthesis and Ecological Function

Mechanisms of Production in Toads

Bufadienolides, the core aglycone components of bufotoxins, are endogenously synthesized by bufonid toads in specialized integumentary glands, including the prominent parotoid macroglands located behind the eyes and smaller mucous and granular glands distributed across the skin. In adult toads, the parotoid glands serve as the primary reservoir, storing toxins in high concentrations for rapid deployment during predation threats via mechanical compression. Tadpoles of species such as Bufo bufo possess unicellular toxin-producing glands that are not uniformly distributed, enabling even in early developmental stages. The biosynthetic pathway commences with as the foundational precursor, which undergoes steroidal modifications to yield bufadienolides characterized by a pregna-14,16-diene-3β-ol backbone with a C17 α-pyrone ring. However, parotoid glands lack the capacity for de novo synthesis; incubations with labeled acetate and mevalonate precursors demonstrate incorporation into cholesterol solely in liver tissue, not glandular tissue, of Bufo viridis (syn. Bufo vienarum). Instead, is synthesized in the liver and transported systemically via plasma lipoproteins, including high-density (HDL) and low-density (LDL) variants, which bind to high-affinity receptors on parotoid gland membranes. Uptake proceeds through , as evidenced by colchicine's inhibition of LDL-cholesterol ester uptake and contrasting effects on HDL, indicating distinct handling mechanisms for these carriers. Bufotoxins proper arise from esterification of bufadienolides (bufogenins) with dicarboxylic acids such as suberic or n-butyric acid, though the enzymatic details of this conjugation remain unelucidated. Intermediate steps in the cholesterol-to-bufadienolide conversion, including , dehydrogenation, and ring formation, are poorly characterized, with no identified enzymes or definitive pathway elucidated to date; proposals include an "acidic" route for specific compounds like marinobufagin, but empirical validation is lacking. Synthesis is dynamic and responsive to ecological pressures: experimental depletion of toxin reserves in Bufo bufo tadpoles via norepinephrine stimulation leads to full restoration within 12 hours, suggesting rapid de novo production capacity. Adult toads similarly upregulate bufadienolide quantities under elevated predation risk, reflecting in glandular output without altering morphology. While microbial biotransformation has been hypothesized for some modifications, evidence supports primarily endogenous toad-driven , distinct from dietary sequestration observed in certain .

Role in Predator Defense

Bufadienolides, the primary toxic components of bufotoxins, function as a chemical deterrent secreted by toads in the Bufonidae family to repel predators. Stored in parotoid macroglands and smaller skin glands, these compounds are released upon mechanical stimulation, such as biting or squeezing, coating the predator's mouth and mucous membranes with irritants that induce immediate aversion through bitter taste, burning sensation, and systemic . The cardiotoxic effects of bufadienolides arise from their inhibition of Na⁺/K⁺-ATPase pumps in , leading to arrhythmias, , and potentially fatal in predators, with lethal doses as low as 0.2–2 mg/kg body weight in mammals. This mechanism enforces learned avoidance; for instance, predators like snakes and mammals that survive initial encounters develop taste aversion, reducing future attacks on toad species. In invasive contexts, such as cane toads (Rhinella marina) in , bufotoxins have decimated naive predators including quolls and varanid , with post-ingestion mortality rates exceeding 90% in some trials. Tadpoles and eggs of bufoid toads also contain bufadienolides, providing early-life defense against aquatic predators like and , though efficacy varies by species; (Bufo bufo) larvae maintain baseline toxin levels without significant upregulation under predation risk, ensuring constitutive protection. Predation pressure influences toxin allocation, with adults in high-risk environments exhibiting larger and higher bufadienolide concentrations, up to 5–10% of dry mass. While primarily antipredator, bufotoxins may secondarily deter parasites and microbes due to their antimicrobial properties, though prioritizes predator deterrence as the evolutionary driver, supported by aposematic coloration in many signaling .

Extraction Methods

Traditional Extraction Techniques

Traditional extraction of bufotoxin, primarily from the parotoid and glands of toads such as Bufo bufo gargarizans and Bufo melanostictus, relied on manual stimulation of live specimens to elicit secretion. Toads were captured during active seasons, typically summer, and restrained gently to avoid or injury that could alter the toxin's composition. Collectors massaged or applied mild pressure to the prominent parotoid glands behind the eyes and along the dorsal , prompting the release of a milky-white rich in bufadienolides conjugated with suberic acid or . The secreted venom was collected by allowing it to drip onto clean glass, porcelain, or cloth surfaces, or by scraping it directly from the toad's skin after irritation. This raw material, often yielding 100-500 mg per toad depending on species and size, was then spread thinly and dried naturally under sunlight or in shaded, ventilated areas to prevent degradation from excessive heat or moisture. The drying process, lasting 1-3 days, transformed the viscous secretion into a hard, waxy cake known as Ch'an Su (Venenum Bufonis) in traditional Chinese medicine, which could be stored indefinitely and later pulverized for use in formulations. This method, documented in Chinese pharmacopeias since at least the (1368-1644 CE), prioritized preservation of bioactive compounds without solvents, though yields varied with environmental factors like diet and stress levels during collection. Historical texts emphasize selecting healthy, mature to ensure potency, with the dried product assayed crudely by (bitter) or tests before medicinal application. Modern analyses confirm that sun-drying minimally alters core structures compared to heat processing, supporting its efficacy in empirical TCM uses for cardiac and inflammatory conditions.

Contemporary Laboratory Methods

Modern laboratory extraction of bufotoxins typically begins with solvent-based methods applied to dried toad venom (Chansu) or glandular secretions, using polar solvents like , , or to solubilize the lipophilic conjugates. These extracts are then fractionated through techniques such as or initial to separate crude components based on polarity. Purification of individual bufotoxins relies on high-resolution chromatographic methods, including high-speed counter-current chromatography (HSCCC) for preparative-scale isolation of major bufadienolides like bufalin and cinobufagin from toad venom, achieving high purity without irreversible adsorption. (HPLC), often in preparative or semi-preparative modes, further refines fractions by reversing-phase separation, enabling the isolation of trace bufotoxins for pharmacological studies. Analytical confirmation and structural elucidation employ hyphenated techniques such as ultra-high-performance liquid chromatography coupled with time-of-flight mass spectrometry (UHPLC-TOF-MS) for comprehensive profiling of bufadienolide content in extracts, providing quantitative data on conjugates like bufotoxins. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is standard for identifying specific bufotoxins, such as arenobufagin, in intoxication cases or venom samples, offering high sensitivity and specificity through multiple reaction monitoring. Nuclear magnetic resonance (NMR) spectroscopy complements these for definitive structural verification post-isolation. To minimize degradation, at controlled temperatures (e.g., 60°C) is integrated prior to extraction, preserving free and conjugated bufadienolides better than traditional heat . These methods have enabled the isolation of novel bufotoxins, such as bufovende A from Venenum bufonis, supporting research into their bioactivities.

Pharmacological Mechanisms

Molecular Targets and Actions

Bufotoxins primarily target the Na⁺/K⁺-ATPase enzyme, a membrane-bound critical for maintaining cellular sodium and potassium gradients. The bufadienolide components bind to the α-subunit of this pump, inhibiting its activity in a manner analogous to cardiac glycosides like . This binding stabilizes the enzyme's phosphorylated E2 conformation, blocking access to the extracellular site and halting ATP-dependent . Inhibition elevates intracellular sodium concentrations, which indirectly increases cytosolic calcium via reversal of the Na⁺/Ca²⁺ exchanger, enhancing at low doses but inducing arrhythmias, , and cellular at toxic levels. Bufadienolides exhibit a preference for the α1 isoform of Na⁺/K⁺-, contributing to their cardiotonic effects. Studies demonstrate dose-dependent inhibition, with activity coefficients correlating blockade to antiproliferative effects in cellular models. Beyond ion transport, bufotoxins modulate additional pathways, including suppression of the signaling cascade, which underlies their and anticancer actions by inhibiting pro-survival gene transcription. Cytotoxic bufadienolides like bufotalin induce and arrest through endoplasmic reticulum stress and activation, independent of Na⁺/K⁺-ATPase in some contexts. These multifaceted interactions highlight bufotoxins' potential therapeutic breadth, though limits clinical translation.

Dose-Dependent Effects

At low doses, bufadienolides in bufotoxin exert cardiotonic effects by inhibiting Na⁺/K⁺-ATPase, which elevates intracellular sodium and calcium levels, thereby enhancing and serving as a potential treatment for , akin to glycosides. This positive inotropic action is observed in concentrations that minimally disrupt balance, with historical applications in using toad venom (Venenum Bufonis) at 3–5 mg daily for adults to support cardiac function without exceeding 135 mg to avoid escalation. As doses increase, the inhibitory effects on Na⁺/K⁺-ATPase intensify, leading to extracellular potassium accumulation (), membrane , and suppression of cardiac conduction, manifesting as , , and gastrointestinal symptoms such as and salivation. In animal models, doses of 4.86–120 mg/kg of Venenum Bufonis precipitate acute poisoning, progressing to ventricular arrhythmias and in severe cases. Lethal outcomes correlate with high-dose exposure, where the therapeutic window narrows dramatically; for instance, while low micromolar concentrations yield antiproliferative benefits against cancer cells via induction, supratherapeutic levels induce widespread , including neurotoxic effects and multi-organ failure, with no observed tachyarrhythmias in toad poisoning cohorts but consistent bradycardic dominance. This biphasic response underscores the narrow margin between efficacy and toxicity, limiting clinical translation without dose optimization.

Toxicity Profiles

Human Intoxication Symptoms and Cases

Human intoxication from bufotoxin, a cardiotoxic found in the of certain toad species such as bufo and gargarizans, primarily manifests as digitalis-like toxicity due to inhibition of Na+/K+-ATPase, leading to elevated intracellular calcium and disrupted . Common initial symptoms include gastrointestinal distress such as , , and abdominal discomfort, often appearing within hours of ingestion or contact with . Cardiovascular effects dominate severe cases, with , , and frequently reported; tachyarrhythmias are less common but can occur in mixed presentations resembling tachy-brady syndrome. Neurological symptoms may include altered , vertigo, , seizures, and increased salivation, while systemic signs such as and can emerge in advanced intoxication. These effects stem from bufotoxin's structural similarity to cardiac glycosides like , with arenobufagin and other components exacerbating dysregulation and myocardial depression. Documented cases are rare but highlight risks from accidental ingestion, such as toad eggs or meat in traditional soups. In one pediatric case, a consuming toad eggs exhibited vertigo, fussiness, and sleepiness, with liquid chromatography-mass spectrometry confirming arenobufagin as the toxin; the patient recovered with supportive care. An 81-year-old woman presented with acute overdose signs including tachy-brady after bufotoxin exposure, resolving after treatment with digoxin-specific Fab fragments. Fatal outcomes have been reported from ingestions of 1.5–6 g of toad venom, often involving refractory and despite interventions. Pediatric poisonings from Bufo bufo gargarizans eggs carry high mortality, underscoring the need for rapid recognition and antidotal therapy. Overall, toad poisoning cohorts show gastrointestinal symptoms in most cases and in severe ones, with lethality tied to dose and delayed treatment.

Veterinary and Wildlife Impacts

Bufotoxin, secreted by toads of the genus Bufo (now Rhinella), poses significant risks to domestic animals, particularly dogs, which frequently encounter and attempt to consume these amphibians. In , intoxication typically occurs when dogs bite or mouth toads, leading to rapid absorption of the toxin through . Clinical signs in affected dogs include profuse (observed in 78% of cases), red oral mucous membranes (63%), , , seizures (31%), cardiac arrhythmias, and potentially fatal or respiratory distress. A retrospective study of 94 dogs exposed to Bufo marinus (cane toad) documented neurologic abnormalities such as tremors and disorientation, with outcomes varying based on prompt intervention. Cats exhibit similar symptoms but less frequently due to lower predatory behavior toward toads. Treatment protocols emphasize immediate decontamination by flushing the oral cavity with copious water to remove residual toxin, followed by supportive care including antiemetics, atropine for , intravenous fluids, and seizure control with . Prognosis improves with rapid veterinary attention; delays can result in death from cardiac or , as bufotoxin's digitalis-like effects disrupt ion channels and induce arrhythmias. In regions with high densities, such as or , seasonal spikes in cases correlate with breeding periods, underscoring the need for pet owner education on prevention. In wildlife contexts, bufotoxin contributes to ecological disruptions, especially via invasive cane toads (Rhinella marina) in , where native predators lacking tolerance suffer lethal toxic ingestion. Predators such as quolls, goannas, snakes, and s experience rapid heartbeat, excessive salivation, convulsions, , and death upon consuming toads, leading to population declines in at least four anurophagous species. For instance, cane toad has caused mass mortality in populations and cascading effects, reducing numbers of frog-eating vertebrates and indirectly benefiting competitors or prey species. Larger toads pose greater risks due to higher toxin loads, exacerbating impacts on naive ecosystems. While some species, like the keelback snake, exhibit partial resistance, widespread declines highlight bufotoxin's role as a primary mechanism rather than competition alone.

Therapeutic Potential and Research

Historical and Traditional Applications

In , dried secretions from the parotoid glands and skin of toads such as bufo gargarizans or Bufo melanostictus, known as Ch'an Su or , have been employed for centuries to treat conditions including , , , and sores. The , which contains bufadienolides like bufalin constituting the primary toxic components of bufotoxin, was collected by stimulating the to secrete the milky substance, which was then dried into cakes for medicinal preparation. These preparations were administered in small doses orally or topically, purportedly for their cardiotonic and effects, as documented in classical texts and empirical practices. Beyond Asia, historical European accounts from the Middle Ages describe the common toad (Bufo bufo) as both a perceived panacea for ailments like epilepsy and dropsy, and a dreaded poison, with venom occasionally applied in folk remedies despite risks of toxicity. In veterinary contexts, extracts from Bufo bufo have been used in Spain to treat hoof rot in livestock, reflecting localized traditional applications of toad secretions for antimicrobial purposes. These uses, however, were not systematically standardized and often intertwined with superstition, contrasting the more codified pharmacopeia of Chinese traditions. Overall, traditional applications emphasized bufotoxin's digitalis-like properties for cardiac stimulation, though without isolation of active compounds until modern analysis.

Modern Pharmacological Studies

Modern pharmacological investigations into bufotoxin have centered on its primary active components, bufadienolides such as bufalin, cinobufagin, and arenobufagin, which exhibit potent bioactivities despite their inherent . These studies, largely preclinical and conducted since the early 2000s, emphasize inhibition of Na⁺/K⁺-ATPase as a core mechanism, akin to glycosides, leading to increased intracellular calcium and subsequent effects on cardiac contractility, , and . Experimental models have demonstrated antiproliferative effects at low nanomolar concentrations, with bufalin showing IC₅₀ values of 0.89–1.28 μM against castration-resistant cells. Anticancer research dominates, revealing bufadienolides' ability to induce via pathways including PI3K/Akt/ suppression, activation, and through GPX4 degradation. xenograft studies, such as those using models, reported bufalin at 1.5 mg/kg reducing tumor volume by 67%, while combinations with agents like hydroxycamptothecin achieved up to 93% inhibition. Similar efficacy has been observed against , , and pancreatic cancers, with mechanisms involving G₂/M arrest and downregulation of migration factors like β-catenin. Bufadienolides also reverse multidrug resistance by inhibiting , enhancing sensitivity in resistant cell lines. Limited clinical exploration includes phase I/II trials of Huachansu, a refined toad venom preparation containing bufadienolides, for (initiated around 2001) and lung/pancreatic cancers (2009–2012), reporting tolerability and preliminary antitumor responses, though larger randomized trials are absent due to concerns. Emerging studies explore antiviral potential, with bufadienolides inhibiting 3CLpro in 2025 docking and enzymatic assays, suggesting a mechanism via covalent binding to catalytic residues. Anti-inflammatory effects via inhibition have been noted , but therapeutic translation remains hindered by the narrow therapeutic window and arrhythmogenic risks from Na⁺/K⁺-ATPase over-inhibition. Ongoing efforts focus on structural modifications and targeted delivery to mitigate while preserving .

Evidence on Efficacy and Limitations

Preclinical studies have demonstrated antiproliferative effects of bufadienolides, the primary active components in bufotoxins, against multiple lines, including , hepatocellular, , and cells, primarily through induction of , cell cycle arrest at G2/M phase, and inhibition of pathways such as , PI3K/Akt/, and STAT3. For instance, bufalin administered intraperitoneally at 1.5 mg/kg reduced tumor volume by 67% in xenograft models over 9 weeks, while cinobufagin suppressed proliferation in cells with values of 50–100 nM via downregulation of anti-apoptotic MCL-1. efficacy has been observed in rodent models of and , where bufalin inhibited production (e.g., TNF-α, IL-6) and activation. Cardiotonic properties, akin to , arise from Na+/K+-ATPase inhibition, supporting traditional uses in , though empirical data remain limited to and animal assays. Human clinical evidence is sparse, confined largely to pilot studies of toad venom extracts like Huachansu injection, which showed preliminary antitumor activity in hepatocellular, , and pancreatic cancers with reportedly low toxicity in a Phase I trial involving advanced patients. No large-scale randomized controlled trials exist for isolated bufadienolides, and efficacy claims derive predominantly from applications (e.g., Chansu for sores and cancers) without rigorous verification. Key limitations include a narrow , with manifesting as arrhythmias, , and potential due to excessive Na+/K+-ATPase inhibition—effects mirroring digoxin overdose and unresponsive to digoxin-specific Fab fragments in some cases. In mice, the LD50 for bufalin approximates 2.2 mg/kg, closely approaching effective doses around 1 mg/kg, exacerbating overdose risks. challenges, compositional variability from sources, and CYP3A4-mediated interactions further hinder clinical translation, alongside insufficient and environmental constraints on sourcing. These factors underscore the gap between promising preclinical data and safe, evidence-based human applications.

Misuse, Controversies, and Conservation

Psychedelic and Recreational Abuse

The parotoid gland secretions of certain toad species, including those containing bufotoxins such as bufadienolides alongside tryptamines like and , have been used recreationally for their psychoactive properties, primarily through rather than ingestion to avoid severe toxicity. This practice, often termed "toad medicine" or "bufo ceremonies," targets intense, short-duration hallucinogenic experiences induced mainly by , a potent serotonergic , with contributing milder visionary effects; however, the cardiotoxic bufadienolides in the venom amplify risks of arrhythmias and during use. Users report ego-dissolution, profound altered states, and purported therapeutic insights, but empirical data on long-term outcomes remain sparse, with most accounts anecdotal from psychedelic communities rather than controlled studies. Recreational demand surged in the , particularly among wellness and spiritual seekers, with ceremonies led by self-proclaimed shamans charging fees for guided sessions involving extraction and inhalation of dried venom from Incilius alvarius (formerly Bufo alvarius), the toad. Documented cases include visits for acute intoxication, such as , followed by , and states, as seen in reports of users experiencing "white-outs" or cardiovascular collapse from overdoses. One peer-reviewed analysis of bufotenin-specific abuse noted , , and anticholinergic-like symptoms, underscoring the non-psychedelic toxicities overlapping with bufotoxin components. potential is debated, with some sources citing in frequent users seeking ego-transcending highs, though physiological withdrawal lacks robust evidence beyond case reports of compulsive redosing. Abuse is facilitated by online sourcing of venom extracts, bypassing direct handling, but purity varies, heightening adulteration risks with synthetic or contaminants; oral , historically rare but documented in accidental or misguided cases, leads to near-fatal gastrointestinal and cardiac effects due to bufotoxin . Regulatory scrutiny has increased, with classified as a Schedule I substance in the U.S. since 2011, yet toad-derived forms evade some controls, prompting warnings from toxicologists about unverified facilitators exploiting vulnerable individuals in unregulated retreats. No large-scale epidemiological data exist on prevalence, but rising interest correlates with broader psychedelic renaissance trends, tempered by documented fatalities in mishandled sessions.

Environmental and Ethical Concerns

The harvesting of bufotoxin-rich venom from toads, particularly Incilius alvarius (Sonoran Desert toad), for extraction of compounds like has raised environmental concerns due to unsustainable practices driven by surging demand in psychedelic communities. "Milking" involves manually stressing the toad—often by restraint and stimulation of parotoid glands—to induce venom secretion, a process that can dehydrate, injure, or kill individuals, while repeated collection depletes local populations in arid habitats like the . Conservationists have documented over-harvesting in breeding hotspots, where toads congregate post-monsoon, exacerbating vulnerability as diminished venom reduces natural defenses against predators. Although I. alvarius holds IUCN Least Concern status globally, subpopulations face localized threats, including near-extinction risks in and endangered listings in , compounded by habitat loss from and climate-induced droughts that already limit breeding success. Ethical issues center on violations inherent in venom extraction, as the physical restraint and glandular manipulation cause documented stress responses, including elevated and potential long-term physiological harm, without standardized humane protocols. Critics argue that commercializing toad-derived bufotoxins prioritizes human recreational or purported therapeutic benefits over , fostering a that incentivizes and ignores synthetic alternatives for , which avoid ecological footprints. Organizations like the Chacruna Institute advocate for toad-free sourcing to mitigate these harms, emphasizing that ethical psychedelic use should not entail exploiting non-renewable wild populations. Furthermore, the lack of regulatory oversight amplifies risks, as unregulated ceremonies promote mass extractions that could cascade into broader losses if demand persists unchecked.

References

  1. https://pubchem.ncbi.nlm.nih.gov/compound/Bufotoxin
  2. https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/bufotoxin
  3. https://aspcapro.org/sites/default/files/j-bufotoadtoxicity.pdf
  4. https://pubmed.ncbi.nlm.nih.gov/37154099/
  5. https://pubmed.ncbi.nlm.nih.gov/36738868/
  6. https://www.liverpooluniversitypress.co.uk/doi/10.3828/transactions.7.16
  7. https://pubmed.ncbi.nlm.nih.gov/8895112/
  8. https://www.accefyn.com/revista/Volumen_16/63/151-156.pdf
  9. https://pmc.ncbi.nlm.nih.gov/articles/PMC6115759/
  10. https://www.jstor.org/stable/769520
  11. https://www.sciencedirect.com/science/article/pii/S0021925820782852/pdf?md5=a16832be3c1f18a57f10be507be63ab9&pid=1-s2-0-S0021925820782852-main.pdf
  12. https://www.nobelprize.org/uploads/2018/06/wieland-lecture.pdf
  13. https://www.sciencedirect.com/science/article/abs/pii/S0039128X24001934
  14. https://pmc.ncbi.nlm.nih.gov/articles/PMC6988675/
  15. https://link.springer.com/content/pdf/10.1007/978-3-642-88605-8_7.pdf
  16. https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2022.1044027/full
  17. https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/bufadienolide
  18. https://analyticalsciencejournals.onlinelibrary.wiley.com/doi/10.1002/ddr.22072
  19. https://www.sciencedirect.com/science/article/abs/pii/S0378874116301763
  20. https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/bufo
  21. https://pubmed.ncbi.nlm.nih.gov/27063985/
  22. https://www.researchgate.net/figure/Structures-of-bufotoxins-R-at-the-3-position-of-the-bufadienolide-structures-are_fig6_370601495
  23. https://pubs.acs.org/doi/10.1021/acs.jafc.4c03184
  24. https://www.mdpi.com/2072-6651/16/3/159
  25. https://onlinelibrary.wiley.com/doi/10.1002/ddr.22072
  26. https://pmc.ncbi.nlm.nih.gov/articles/PMC6477007/
  27. https://www.aspca.org/news/trouble-toads-getting-bottom-toxic-threat
  28. https://www.nature.com/articles/s41598-019-39587-3
  29. https://www.carleton.edu/arboretum/about/species/fauna/reptiles/toad/
  30. https://www.frontiersin.org/journals/ecology-and-evolution/articles/10.3389/fevo.2022.924248/full
  31. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/bufo
  32. https://pmc.ncbi.nlm.nih.gov/articles/PMC10912398/
  33. https://animaldiversity.org/accounts/Rhinella_marina/
  34. https://www.journals.uchicago.edu/doi/10.1086/655116
  35. https://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=48
  36. https://www.dcceew.gov.au/environment/biodiversity/threatened/key-threatening-processes/biological-effects-cane-toads
  37. https://www.nature.com/articles/s41598-019-52641-4
  38. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/bufo-bufo
  39. https://www.researchgate.net/publication/345100980_Variation_in_Bufadienolide_Composition_of_Parotoid_Gland_Secretion_From_Three_Taxa_of_Japanese_Toads
  40. https://www.mdpi.com/1420-3049/26/14/4217
  41. https://pmc.ncbi.nlm.nih.gov/articles/PMC6395641/
  42. https://www.sciencedirect.com/science/article/pii/S0039128X84800124
  43. https://pmc.ncbi.nlm.nih.gov/articles/PMC5677481/
  44. https://academic.oup.com/iob/article/5/1/obad021/7190629
  45. https://pmc.ncbi.nlm.nih.gov/articles/PMC11321852/
  46. https://pmc.ncbi.nlm.nih.gov/articles/PMC6580299/
  47. https://www.nature.com/articles/s41598-020-80191-7
  48. https://frontiersinzoology.biomedcentral.com/articles/10.1186/s12983-023-00499-8
  49. https://www.sciencedirect.com/science/article/pii/S2590171022000029
  50. https://www.sciencedirect.com/science/article/abs/pii/S0024320502023020
  51. https://www.nature.com/articles/s41598-025-89809-0
  52. https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2023.1137547/full
  53. https://pmc.ncbi.nlm.nih.gov/articles/PMC4331950/
  54. https://journals.sagepub.com/doi/10.1177/1934578X1000500709
  55. https://www.sciencedirect.com/science/article/pii/S2352551724000702
  56. https://www.sciencedirect.com/science/article/abs/pii/S0731708515300121
  57. https://www.researchgate.net/publication/396012713_Isolation_of_a_novel_bufadienolide_bufovende_A_and_seven_known_analogs_from_Venenum_bufonis_with_inhibitory_activity_on_hepatic_stellate_cell_activation
  58. https://journals.physiology.org/doi/full/10.1152/ajprenal.00042.2012
  59. https://www.nature.com/articles/srep29155
  60. https://www.ajkd.org/article/S0272-6386%2810%2900560-3/abstract
  61. https://pmc.ncbi.nlm.nih.gov/articles/PMC5600443/
  62. https://www.researchgate.net/publication/370601495_Toad_venom_bufadienolides_and_bufotoxins_An_updated_review
  63. https://pmc.ncbi.nlm.nih.gov/articles/PMC8727535/
  64. https://search.informit.org/doi/pdf/10.3316/informit.216366080876670
  65. https://pmc.ncbi.nlm.nih.gov/articles/PMC7752649/
  66. https://pmc.ncbi.nlm.nih.gov/articles/PMC1769273/
  67. https://journals.sagepub.com/doi/10.1177/1024907918807526
  68. https://pmc.ncbi.nlm.nih.gov/articles/PMC11381761/
  69. https://pmc.ncbi.nlm.nih.gov/articles/PMC11772289/
  70. https://www.sciencedirect.com/science/article/abs/pii/S0041010122002197
  71. https://pubmed.ncbi.nlm.nih.gov/15887382/
  72. https://www.merckvetmanual.com/toxicology/toad-poisoning/toad-poisoning-in-dogs-and-cats
  73. https://avmajournals.avma.org/downloadpdf/journals/javma/216/12/javma.2000.216.1941.pdf
  74. https://vcahospitals.com/know-your-pet/toad-poisoning-in-dogs
  75. https://www.petmd.com/dog/poisoning/toad-venom-poisoning-in-dogs
  76. https://www.dvm360.com/view/toxicology-case-successful-treatment-bufo-marinus-intoxication-dog
  77. https://www.sciencedirect.com/science/article/abs/pii/S0006320708001511
  78. https://australian.museum/blog/amri-news/whos_eating_cane_toads/
  79. https://pmc.ncbi.nlm.nih.gov/articles/PMC4588653/
  80. https://journals.sagepub.com/doi/abs/10.3181/00379727-26-4311
  81. https://stri.si.edu/story/frog-toxins-medicine
  82. https://pubmed.ncbi.nlm.nih.gov/40616739/
  83. https://www.researchgate.net/publication/50420836_Bufadienolides_and_their_Antitumor_Activity
  84. https://www.sciencedirect.com/science/article/abs/pii/S0940299310001703
  85. https://pmc.ncbi.nlm.nih.gov/articles/PMC5992390/
  86. https://www.addictioncenter.com/drugs/hallucinogens/toad-venom-addiction-abuse/
  87. https://jheor.org/post/2542-from-toad-toxin-to-medicine-the-promise-of-5-meo-dmt
  88. https://www.nytimes.com/2022/03/20/us/toad-venom-psychedelic.html
  89. https://www.addictioncenter.com/news/2019/10/trendy-psychedelic-toad-venom/
  90. https://www.sciencedirect.com/topics/medicine-and-dentistry/bufotenine
  91. https://discoverhealthgroup.com/addiction/drug/toad-venom/
  92. https://www.texasobserver.org/bufo-brooke-tarrer-universal-shamans-new-tomorrow-psychedelics/
  93. https://psychedelicstoday.com/2018/10/03/ethics-ecology-bufotoxins/
  94. https://www.euronews.com/green/2022/03/23/conservationists-plead-with-public-to-stop-milking-toads
  95. https://chacruna.net/5-meo-dmt_toad_conservation_psychedelic/
  96. https://five-meo.education/conservation-awareness/
  97. https://psychedelicstoday.com/2025/08/15/toad-truth-and-the-trouble-with-5-meo-why-bufo-alvarius-needs-our-protection/
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