Open Access Articles- Top Results for Oenanthotoxin


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IUPAC name
Other names
Enanthotoxin, Horsebane, Dead Tongue, Dead Man's Fingers, herba sardonica
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20311-78-8 7pxY
ChEMBL ChEMBL550225 7pxN
ChemSpider 24616929 7pxN
Jmol-3D images Image
KEGG C20044 7pxN
PubChem Template:Chembox PubChem/format
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This page is a soft redirect. Properties

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Molar mass 258.355 g/mol
Melting point 86°C
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
 14pxN verify (what is10pxY/10pxN?)
Infobox references

Oenanthotoxin—commonly known as “the most poisonous plant in Britain” [1]— is a toxin extracted from hemlock water dropwort (Oenanthe crocata) and other plants of the genus Oenanthe. It is a central nervous system poison, and acts as a noncompetitive gamma-aminobutyric acid antagonist.[2] A case has been made for the presence of this toxin in local Oenanthe species playing a causative role in euthanasia in ancient Sardinia.[3][4] It was crystallized in 1949 by Clarke and co-workers.[5] It is structurally closely related to the toxins cicutoxin[6] and carotatoxin.[7][8]


The name Oenanthotoxin originates from the Greek oinos meaning wine and anthos meaning flower.[9] This is fitting due to the sweet smell the plant produces and the state of bemusement that relates to drunkenness.[10]

More common names include Horsebane, Dead Tongue, and Dead Man’s Fingers[11]—due to the physical appearance of the plant’s roots. In ancient literature, the plant is referred to as herba sardonica, due to it’s infamy in ancient Sardinia.[12]

Appearance and Properties

Physical Appearance

O. crocata typically grows in damp, marshy environments. Commonly mistaken for edible plants such as Alexanders and Parsnips,[1] the Water Dropwort can grow up to 1.5m with hollow stems. Triangular, blunt tooth-edged leaves grow on the stems and can exist up to 30 cm in length. Water Dropworts are abundant in white and green flowers that form an umbel shape.[2][9]

Physical Properties

Oenanthotoxin toxicity is dependent on seasonal changes and geographical location, the most is present during late winter and early spring.[9] Oenanthotoxin is a C17 polyacetylene isomer of cicutoxin. Contrary to most poisonous plants that contain bitter tastes or burning sensations, the Water Dropwort has a rather sweet and pleasant taste and odor.[10]

Oenanthe crocata is characterized by a yellow liquid that changes color due to air exposure.[2][10] The roots are the most toxic part, although the entire plant contains poisonous properties.[9] Unlike the majority of poisonous plants, the poisonous properties are not lost due to plant drying.[13]

History and Culture

The discovery and usage of the plant predates Socrates and Homer and its first use as a poison is thought to have been implemented between 1800 BCE and 800 BCE in Pre-Roman Sardinia.[10][14] In Ancient Sardinia, it was considered to be a humane form of euthanasia. Elderly people who were unable to care for themselves were given the herb and dropped from a high rock to ensure death.[10][14] It is also believed that Socrates ingested this plant to commit suicide.[15]

A common symptom of Oenanthotoxin is risus sardonicus, better known as the Sardonic Grin, coined by Homer in the 8th century BCE, due to the victim's rigid smile after ingestion. This common feature is associated with the poisonous gas The Joker uses to murder his victims in the DC Batman comics.[16]

Furthermore as a muscle relaxant, it is believed to have cosmetic botox properties in small amounts.[14]

Mechanism of Action

Although Oenanthotoxin is a relatively well known poison, its mechanism of action is not entirely understood. However, there is evidence that it is similar to the mechanism of cicutoxin.

Oenanthotoxin is part of a group of C17 conjugated polyacetylenes that act as noncompetitive gamma-aminobutyric acid (GABA) inhibitors in the Central Nervous System. GABA binds to the beta-domain of the GABAA receptor in the Central Nervous System and activates the receptor causing chloride ions to flow across the membrane which hyperpolarizes the neuron.[2] When Oenanthotoxin is introduced to the body, it non-competitively binds to the same beta-domain receptor as GABA would have and prevents normal inhibitory function. Binding to the same receptor, Oenanthotoxin blocks the chloride channel, allowing depolarization to continue. This causes hyperactivity in the neurons, resulting in convulsions and seizures and thus blocking GABAergic responses [10]


While Oenanthotoxin is extremely dangerous and toxic (LD50 = 0.58 mg/kg for mice),[2] there have been numerous case studies documenting the common symptoms including: convulsions, seizures, nausea, diarrhea, tachycardia, mydriasis, rhabdomyolysis, renal failure, respiratory impairment, and cardiac dysrhythmias.[2][9][10] Note: there is no standard protocol for curing the biological metabolism of Oenanthotoxin.

Below is a comprehensive table listing the recorded symptoms caused Oenanthotoxin within each system in the body Oenanthe crocata:[2]

Organ System Symptoms
Neurological slurred speech, dizziness, paresthesia, delirium, ataxia, coma, seizures, trismus, hyperreflexia, opisthotonus, spasms, cerebral edema, status epilepticus
Gastrointestinal nausea, vomiting, salivation, abdominal pain
Respiratory congestion, distress, depression, airway obstruction, arrest, apnea
Cardivascular tachicardia, brachycardia, hypertension, hypotension, cardiac dysrhythmias, cardiac arrest
Renal glycosuria, proteinuria, hematuria, oliguria, myoglobinuria, acute renal failure
Musculoskeletal weakness, muscle spasms, muscle rigidity, rhabdomyolysis
Metabolic elevated temperature, liver dysfunction, hypokalemia, lactic dehydrogenase, disseminating (intravascular, coagulation), metabolic acidosis, azotemia
Occular mydriasis
Dermal diaphoresis, cyanosis, flushed face


  1. ^ a b Walson, J. P. (July 2012), Hemlock Water Dropwort: The Most Poisonous Plant in Britain… 
  2. ^ a b c d e f g Schep, L. J.; Slaughter, R. J.; Becket, G.; Beasley, D. M. G. (2009). "Poisoning due to Water Hemlock". Clinical Toxicology 47 (4): 270–278. PMID 19514873. doi:10.1080/15563650902904332.  edit
  3. ^ Appendino, G.; Pollastro, F.; Verotta, L.; Ballero, M.; Romano, A.; Wyrembek, P.; Szczuraszek, K.; Mozrzymas, J. W.; Taglialatela-Scafati, O. (2009). "Polyacetylenes From Sardinian Oenanthe fistulosa: A Molecular Clue to risus sardonicus". Journal of Natural Products 72 (5): 962–965. PMC 2685611. PMID 19245244. doi:10.1021/np8007717.  edit
  4. ^ Choi, C. Q.; Harmon, K.; Matson, J. (August 2009). "News Scan Briefs: Killer Smile". Scientific American. 
  5. ^ E. G. C. Clarke, D. E. Kidder and W. D. Robertson (1949) J. Pharm. Pharmacol. 1 377-381.
  6. ^ Anet, E. F. L. J.; Lythgoe, B.; Silk, M. H.; Trippett, S. (1953). "Oenanthotoxin and Cicutoxin. Isolation and Structures". Journal of the Chemical Society 1953: 309–322. doi:10.1039/JR9530000309. 
  7. ^ King, L. A.; Lewis, M. J.; Parry, D.; Twitchett, P. J.; Kilner, E. A. (1985). "Identification of Oenanthotoxin and Related Compounds in Hemlock Water Dropwort Poisoning". Human Toxicology 4 (4): 355–364. PMID 4018815. doi:10.1177/096032718500400401. 
  8. ^ Anet, E. F. L. J.; Lythgoe, B.; Silk, M. H.; Trippett, S. (1952). "The Chemistry of Oenanthotoxin and Cicutoxin". Chemistry and Industry 31: 757–758. 
  9. ^ a b c d e "Information Sheet: 31 Hemlock Water Dropwort (Oenanthe crocata)" (PDF). Centre for Ecology & Hydrology. Centre for Aquatic Plant Management. Retrieved 2005. 
  10. ^ a b c d e f g Appendino, G.; Pollastro, F.; Verotta, L. (2009), "Polyacetylenes from Sardinian Oenanthe Fistulosa: A Molecular Clue to risus sardonicus", J. Nat. Prod. 72: 962–965 
  11. ^ Grieve, M., Dropwort, Hemlock Water 
  12. ^ Lorenzi, Rossela. "'Sardonic Grin' Has Roots in Poisonous Herb". Discovery. Retrieved May 20, 2009. 
  13. ^ Egdahl, A. (1911). "A case of poisoning due to eating poison hemlock (Cicuta maculata) with a review of reported cases". Arch Intern Med 7: 348–356. 
  14. ^ a b c Owen, James. "Ancient Death-Smile Potion Decoded?". National Geographic. Journal of Natural Products. Retrieved June 2, 2009. 
  15. ^ Bletchly, Rachael. "Killers in your garden; Beware these poison plants". The Free Library. Gale, Cengage Learning. 
  16. ^ Ruekber, Ben (July 2010). "A Chemistry Tidbit for Batman Fans". J. Chem. Educ. 87 (10): 1017–1018. doi:10.1021/ed1003228.