skatole

Skatole is derived from the amino acid tryptophan in the digestive tract of mammals. Tryptophan is converted to indoleacetic acid, which decarboxylates to give the methylindole.{{cite journal |last1= Whitehead |first1= T. R. |last2= Price |first2= N. P. |last3= Drake |first3= H. L. |last4= Cotta |first4= M. A. |title= Catabolic pathway for the production of skatole and indoleacetic acid by the acetogen Clostridium drakei, Clostridium scatologenes, and swine manure |journal= Applied and Environmental Microbiology |volume = 74|issue = 6|pages = 1950–3|pmid= 18223109 |pmc = 2268313|date= 25 January 2008 |doi = 10.1128/AEM.02458-07|bibcode= 2008ApEnM..74.1950W }}{{cite journal|doi=10.1093/ajcn/32.1.173|pmid=367144|title=Microbial metabolites of tryptophan in the intestinal tract with special reference to skatole|journal=The American Journal of Clinical Nutrition|volume=32|issue=1|pages=173–178|year=1979|last1=Yokoyama|first1=M. T.|last2=Carlson|first2=J. R.|doi-access=free}} Once it is created in the digestive tract of mammals, it is metabolized by cytochrome P450 enzymes in the liver.{{cite journal|last1=Bilić-Šobot|first1=Diana|last2=Zamaratskaia|first2=Galia|last3=Rasmussen|first3=Martin Krøyer|last4=Čandek-Potokar|first4=Marjeta|last5=Škrlep|first5=Martin|last6=Povše|first6=Maja Prevolnik|last7=Škorjanc|first7=Dejan|date=2016-10-20|title=Chestnut wood extract in boar diet reduces intestinal skatole production, a boar taint compound|url=https://link.springer.com/article/10.1007/s13593-016-0399-1#auth-Maja_Prevolnik-Pov_e-Aff1-Aff4|journal=Agronomy for Sustainable Development|language=en|location=Germany|publisher=Springer Science+Business Media|publication-place=Germany|volume=36|article-number=62|doi=10.1007/s13593-016-0399-1|doi-access=free|isbn= |issn=1773-0155|oclc=8092619612|access-date= }}

Skatole can be synthesized via the Fischer indole synthesis.Emil Fischer (1886) [https://books.google.com/books?id=okE3AAAAYAAJ&pg=RA1-PA126 "Indole aus Phenylhydrazin"] (Indole from phenylhydrazine), Annalen der Chemie, vol. 236, pages 126-151; for Fischer's synthesis of skatole, see page 137. (Fischer was not the first to prepare skatole. It was prepared, via other methods, in 1880 by von Baeyer, and in 1883 by Otto Fischer and German and by Fileti.)

It gives a violet color upon treatment with potassium ferrocyanide.{{citation needed|date=January 2022}}

Skatole, along with the fecal odorant indole, can be neutralized by combining it with other scents, by producing perfumes or air fresheners that lack skatole and indole. In a manner similar to noise-cancelling headphones, the scent produced by the resultant concentrations of skatole and indole relative to other substances in the freshener is thus "in-phase" and perceived as pleasant.{{cite news|url=https://www.nytimes.com/1990/07/15/business/technology-making-bad-smell-good-by-tricking-the-nose.html|title=Technology; Making Bad Smell Good by Tricking the Nose|newspaper=The New York Times|date=15 July 1990|last1=Holusha|first1=John}}

{{See also|Aphodius}}

Skatole is one of many compounds that are attractive to males of various species of orchid bees, which apparently gather the chemical to synthesize pheromones; it is commonly used as bait for these bees for study.{{cite journal |author1=Schiestl, F.P. |author2=Roubik, D.W. |name-list-style=amp |year=2004 |title=Odor Compound Detection in Male Euglossine Bees | journal= Journal of Chemical Ecology |volume = 29 |pages=253–257 | doi=10.1023/A:1021932131526 | pmid=12647866 | issue=1|hdl=20.500.11850/57276 |s2cid=2845587 |hdl-access=free }} It is also known for being an attractant for the Tasmanian grass grub beetle (Aphodius tasmaniae).{{cite journal |last1= Osborne |first1= G. O. |last2= Penman |first2= D. R. |last3= Chapman |first3= R. B. |title= Attraction of Aphodius tasmaniae Hope to skatole. |journal= Australian Journal of Agricultural Research |volume= 26 |issue= 5 |pages= 839–841 |date= 1975 |doi= 10.1071/AR9750839 }}

Skatole has been shown to be an attractant to gravid mosquitoes in both field and laboratory conditions. Because this compound is present in feces, it is found in combined sewage overflows (CSO), as streams and lakes containing CSO water have untreated human and industrial waste. CSO sites are thus of particular interest when studying mosquito-borne diseases such as West Nile virus.{{cite journal|last1=Beehler|first1=J W|last2=Millar|first2=J G|last3=Mullah|first3=M S|year=1994|others= |title=Field evaluation of synthetic compounds mediating oviposition in Culex mosquitoes (Diptera: Culicidae)|url=https://link.springer.com/article/10.1007/BF02064436|format= |department= |journal=Journal of Chemical Ecology |type= |series= |language=en|edition= |location= |publisher=Springer Science+Business Media|publication-place=Germany|volume=20|pages=281–291|bibcode=1994JCEco..20..281B|doi=10.1007/BF02064436|oclc=5655055511|pmid=24242053|s2cid=23784247|access-date= }}

The release of skatole by certain parasitic wasps in the family Bethylidae is used to determine which subfamily the species belongs to. Species of the Epyrinae subfamily release skatole, while those in the Bethylinae subfamily release a different chemical, spiroacetal.MARLÈNE GOUBAULT, TIM P. BATCHELOR, ROBERTO ROMANI, ROBERT S. T. LINFORTH, MATTHIAS FRITZSCHE, WITTKO FRANCKE, IAN C. W. HARDY, Volatile chemical release by bethylid wasps: identity, phylogeny, anatomy and behaviour, Biological Journal of the Linnean Society, Volume 94, Issue 4, August 2008, Pages 837–852, https://doi.org/10.1111/j.1095-8312.2008.01022.x

Skatole occurs naturally in the feces of all species of mammals and birds, and in the bovine rumen.{{cite journal |last1=Yokoyama |first1=M. T. |last2=Carlson |first2=J. R. |last3=Holdeman |first3=L. V. |date=1977 |title=Isolation and characteristics of a skatole-producing Lactobacillus sp. from the bovine rumen |url= |journal=Applied and Environmental Microbiology |volume=34 |issue=6 |pages=837–842 |doi=10.1128/AEM.34.6.837-842.1977 |pmid=563703 |pmc=242757 |bibcode=1977ApEnM..34..837Y }}

Skatole has been shown to cause pulmonary edema in goats, sheep, rats, and some strains of mice. It appears to selectively target club cells, which are the major site of cytochrome P450 enzymes in the lungs. These enzymes convert skatole to a reactive intermediate, 3-methyleneindolenine, which damages cells by forming protein adducts (see fog fever).{{cite journal |last1= Miller

|first1= M |last2= Kottler |first2= S |last3= Ramos-Vara |first3= J |last4= Johnson |first4= P |last5=Ganjam |first5=V |last6= Evans |first6= T | year = 2003

| title = 3-Methylindole Induces Transient Olfactory Mucosal Injury in Ponies |journal= Veterinary Pathology |volume= 40 |pages= 363–70 |doi= 10.1354/vp.40-4-363 |pmid= 12824507 |issue= 4 |doi-access= free }}

With the testicular steroid androstenone, skatole is regarded as a principal determinant of boar taint.{{cite journal |last1= Wesoly |first1= R.|last2= Weiler |first2= U. |title= Nutritional Influences on Skatole Formation and Skatole Metabolism in the Pig. |journal = Animals |volume = 2|issue = 2|pages = 221–242|pmc = 4494329|year = 2012|pmid = 26486918|doi = 10.3390/ani2020221|doi-access= free}} High amounts of skatole stored in the fat tissue of pigs corresponds with boar taint. To address this, vaccinations with an immunogenic amount of Lawsonia intracellularis antigen are being studied. This antigen reduces the uptake of skatole into the fat of pigs, thus reducing the effect of boar taint.Moki, R.; Sakamoto, E.; Yamaguchi, T. Method For Reducing Skatole And/or Indole In Animals. United States Patent 10792352. Jun 10, 202. Another method used to address skatole concentration in fat tissue is supplementing the pig's diet with 3% chestnut wood extract. This method showed that intestinal skatole concentration decreased by more than 50%.

Skatole contributes to bad breath.{{cite journal|url= https://www.scientificamerican.com/article/beat-bad-breath-keep-mouth-bacteria-happy |title= To Beat Bad Breath, Keep the Bacteria in Your Mouth Happy |first1= Deborah |last1= Franklin|journal=Scientific American |date= 1 May 2013 |volume= 308 |issue= 5 |pages= 30, 32 |doi= 10.1038/scientificamerican0513-30 |pmid= 23627212 |accessdate= 3 November 2020}}

Skatole is the starting material in the synthesis of atiprosin.

• 1-Methylindole
• 2-Methylindole (methylketol)
• 5-Methylindole
• 7-Methylindole
• Cadaverine

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Category:Methylindoles

Category:Foul-smelling chemicals

Category:Perfume ingredients