Thujone: Wikis

  
  

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β-Thujone
Identifiers
CAS number 471-15-8,  (β-thujone)
[546-80-5], (α-thujone)
PubChem 261491
SMILES
Properties
Molecular formula C10H16O
Molar mass 152.23 g/mol
Density 0.92 g/cm³
Boiling point

201 °C, 474 K, 394 °F

Solubility in water Insoluble
Solubility in ethanol Soluble
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Thujone is a ketone and a monoterpene that exists in two stereoisomeric forms: (+)-3-thujone or α-thujone and (−)-3-thujone or β-thujone. It has a menthol odor. Even though it is best known as a chemical compound in the spirit absinthe, recent tests show absinthe contains only small quantities of thujone, and may or may not be responsible for absinthe's reported psychedelic effects. Thujone acts on GABA and 5-HT3 receptors[1] in the brain. In many countries the amount of thujone allowed in food or drink products is regulated.

Contents

Sources

Thujone is found in a number of plants, such as arborvitae (genus Thuja, hence the derivation of the name), Nootka Cypress, some junipers, mugwort, oregano, common sage, tansy and wormwood, most notably grand wormwood (Artemisia absinthium), usually as a mix of isomers in a 1:2 ratio. It is also found in various species of mentha (mint).

Pharmacology

Based on studies that looked only at molecular shape, for many years thujone was thought to act similarly to THC on the cannabinoid receptors.[2] Today this is known to be false because studies have shown that thujone does not activate these receptors.[3] Thujone is a GABAA receptor antagonist.[4] By inhibiting GABA receptor activation neurons may fire more easily which can cause muscle spasms and convulsions.[5]

A toxicology study in mice of alpha-thujone, the more active of the two isomers, found that the median lethal dose, or LD50, is around 45 mg/kg, with 0% mortality rate at 30 mg/kg and 100% at 60 mg/kg. Mice exposed to the higher dose had convulsions that led to death in 1 minute. From 30 to 45 mg/kg the mice experienced muscle spasms in the legs which progressed to general convulsions until death or recovery. Pretreatment with diazepam, phenobarbital or 1 g/kg of ethanol protected against a lethal 100 mg/kg dose. These findings are in line with other GABA antagonists. The study also found that alpha-thujone was metabolized quickly in the liver.[5]

Researchers at Rutgers University [6] tested attention performance with low and high doses of thujone in alcohol. The researchers administered 0.28 mg/kg in alcohol, 0.028 mg/kg in alcohol and just alcohol to their subjects. The high dose had a short term negative effect on attention performance. The lower dose showed no noticeable effect.[7]

Thujone is reported to be toxic to both brain and liver cells and could cause convulsions if used in too high a dose. Other thujone-containing plants such as the tree Arbor vitae (Thuja occidentalis) are used in herbal medicine, mainly for their immune-system stimulating effects. Side-effects from the essential oil of this plant include anxiety and sleeplessness, which confirms the central nervous system effects of thujone.[8]

Thujone in absinthe

Thujone is most famous for being a compound in the spirit absinthe, and some modern producers list their estimated thujone levels on the bottle. In the past it was thought that absinthe contained up to 260–350 mg/L thujone,[9] but tests have shown this to be false. A 2005 study recreated three 1899 high-wormwood recipes and tested them with gas chromatography-mass spectrometry (GC-MS). The highest contained 4.3 mg/L thujone. A 1930s Pernod Tarragona was also tested and contained 1.8 mg/L thujone.[10] These results match earlier findings showing a vintage 1900s bottle contained 6 mg/L.[11] GC-MS testing is important in this capacity, because gas chromatography alone may record an inaccurately high reading of thujone as other compounds may interfere with and add to the apparent measured amount.[12] Through these tests it has become evident that authentic absinthe contains very little thujone. Anyone bingeing on absinthe would die of alcohol poisoning long before the thujone could cause any life-threatening effects.[13]

History

The compound was discovered after absinthe became popular in the mid 1800s. Dr. Valentin Magnan, who studied alcoholism, tested pure wormwood oil on animals and discovered it caused an epileptic reaction independent from the effects of alcohol. Based on this, it was assumed that absinthe, which contains a small amount of wormwood oil, was more dangerous than ordinary alcohol. Eventually thujone was isolated as the cause of these reactions. Magnan went on to study 250 abusers of alcohol and noted that those who drank absinthe had epileptic attacks and hallucinations. In light of modern evidence, these conclusions are questionable, as they are based on a poor understanding of other compounds and diseases, and clouded by Magnan's belief that alcohol and absinthe were "degenerating" the French race.[14]

After absinthe was banned, research dropped off until the 1970s when Nature magazine published an article comparing the molecular shape of thujone to THC, and hypothesized it would act the same way on the brain, sparking the myth that thujone was a cannabinoid.[2]

More recently, following European Council Directive No. 88/388 [1] allowing certain levels of thujone in foodstuffs in the EU, the studies described above were conducted and found only minute levels of thujone in absinthe.

Regulations

European Union

Maximum thujone levels in the EU are:[15]

  • 0.5 mg/kg in food not prepared with sage and non alcoholic beverages.
  • 5 mg/kg in alcoholic beverages with 25% or less ABV.
  • 10 mg/kg in alcoholic beverages with more than 25% ABV.
  • 25 mg/kg in food prepared with sage.
  • 35 mg/kg in alcohol labeled as bitters.

United States

Foods or beverages that contain Artemisia species, White Cedar, oak moss, tansy or Yarrow must be thujone-free.[16] Other herbs that contain thujone have no restrictions. For example, sage and sage oil (which can be up to 50% thujone) are on the Food and Drug Administration's list of substances generally recognized as safe.[17] Absinthe offered for sale in the United States must be "thujone-free", which is interpreted as containing less than 10 mg/kg .[18] There are now therefore a number of thujone-containing absinthes that can be legally imported.[19]

Canada

In Canada, liquor laws are the domain of the provincial governments. British Columbia has no limits on thujone content; Alberta, Ontario and Nova Scotia allow 10 mg/kg thujone; Québec allows 5 mg per kg[citation needed]; Manitoba allows 6–8 mg thujone per litre; and all other provinces do not allow the sale of absinthe containing thujone[citation needed] (although, in Saskatchewan, one can purchase any liquor available in the world upon the purchase of a minimum of one case, usually twelve 750-mL bottles or 9L). The individual liquor boards must approve each product before it may be sold on shelves.

References

  1. ^ Deiml T, Haseneder R, Zieglgänsberger W, Rammes G, Eisensamer B, Rupprecht R, Hapfelmeier G (Feb 2004). "Alpha-thujone reduces 5-HT3 receptor activity by an effect on the agonist-reduced desensitization". Neuropharmacology 46 (2): 192–201. 
  2. ^ a b Conrad III, Barnaby; (1988). Absinthe History in a Bottle. Chronicle books. ISBN 0-8118-1650-8 p. 152
  3. ^ Meschler JP, Howlett AC (March 1999). "Thujone exhibits low affinity for cannabinoid receptors but fails to evoke cannabimimetic responses". Pharmacol. Biochem. Behav. 62 (3): 473–80. PMID 10080239. http://linkinghub.elsevier.com/retrieve/pii/S0091-3057(98)00195-6. 
  4. ^ Olsen RW (April 2000). "Absinthe and gamma-aminobutyric acid receptors". Proc. Natl. Acad. Sci. U.S.A. 97 (9): 4417–8. PMID 10781032. PMC 34311. http://www.pnas.org/cgi/content/full/97/9/4417. 
  5. ^ a b Höld KM, Sirisoma NS, Ikeda T, Narahashi T, Casida JE (April 2000). "Alpha-thujone (the active component of absinthe): gamma-aminobutyric acid type A receptor modulation and metabolic detoxification". Proc. Natl. Acad. Sci. U.S.A. 97 (8): 3826–31. doi:10.1073/pnas.070042397. PMID 10725394. PMC 18101. http://www.pnas.org/cgi/content/full/97/8/3826. 
  6. ^ Absinthe: Attention Performance and Mood under the Influence of Thujone. A. Dettling, H. Grass, A. Schuff, G. Skopp, P. Strohbeck-Kuehner, H.-Th. Haffner. Retrieved Mar. 26, 2008.
  7. ^ Absinthe: Attention Performance and Mood under the Influence of Thujone. DETTLING, A., GRASS, H., SCHUFF, A., SKOPP, G., STROHBECK-KUEHNER, P. AND HAFFNER, H.-TH. (2004) Retrieved Oct. 28, 2006.
  8. ^ Naser B, Bodinet C, Tegtmeier M, Lindequist U. Thuja occidentalis (Arbor vitae): A Review of its Pharmaceutical, Pharmacological and Clinical Properties. Evidence Based Complementary and Alternative Medicine. 2005 Mar;2(1):69–78.
  9. ^ Absinthism: a fictitious 19th century syndrome with present impact, Padosch et al. Retrieved Oct. 28, 2006.
  10. ^ Thujone—Cause of absinthism? Lachenmeier, Emmert et al. Retrieved Oct. 28, 2006.
  11. ^ Thujone Separating Myth from Reality Ian Hutton Retrieved Oct. 28, 2006.
  12. ^ Determination of a-/b-Thujone and Related Terpenes in Absinthe using Solid Phase Extraction and Gas Chromatography, Emmert et al. Retrieved Oct. 28, 2006.
  13. ^ Howstuffworks "Does absinthe really cause hallucinations?"
  14. ^ Conrad III, Barnaby; (1988). Absinthe History in a Bottle. Chronicle books. ISBN 0-8118-1650-8 Pg. 101-105
  15. ^ Opinion of the Scientific Committee on Food on Thujone Scientific Committee on Food (2003) Retrieved Oct 28, 2006.
  16. ^ FDA Regulation 21 CFR 172.510 - Food Additives Permitted for Direct Addition to Food for Human Consumption. Food and Drug Administration (2003). Retrieved Oct 28, 2006.
  17. ^ Substances generally recognized as safe. Food and Drug Administration (2003). Retrieved Oct 28, 2006.
  18. ^ Department of the Treasury Alcohol and Tobacco Tax and Trade Bureau Industry Circular 2007-5 October 17, 2007. Retrieved May 5, 2009
  19. ^ http://drinklucid.com/faq.cfm Retrieved Nov. 29, 2007.

External links

  • Absinthe absolved, Cern Courier, July 8, 2008
  • Thujone.Info — Databank of peer reviewed articles on thujone, absinthe, absinthism, and independent thujone ratings of some commercial brands.
  • The Shaky History of Thujone - Wormwood Society article on thujone and its history.
  • Lachenmeier DW, Nathan-Maister D, Breaux TA, Sohnius EM, Schoeberl K, Kuballa T (May 2008). "Chemical composition of vintage preban absinthe with special reference to thujone, fenchone, pinocamphone, methanol, copper, and antimony concentrations". J. Agric. Food Chem. 56 (9): 3073–81. doi:10.1021/jf703568f10.1021/jf703568f. PMID 18419128. 







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