{{Use dmy dates|date=December 2020}} {{chembox | Name = Eucalyptol | ImageFile1 = Eucalyptol clean.svg | ImageClass1 = skin-invert-image | ImageName = Eucalyptol | ImageFileL1 = Eucalyptol3D-3.png | ImageClassL1 = bg-transparent | ImageFileR1 = Eucalyptol3D-4.png | ImageClassR1 = bg-transparent | IUPACName = 1,3,3-Trimethyl-2-oxabicyclo[2.2.2]octane | OtherNames = 1,8-Cineole<br>1,8-Epoxy-''p''-menthane<br>Cajeputol<br>1,8-Epoxy-''p''-menthane<br>1,8-Oxido-''p''-menthane<br>Eucalyptole<br>1,3,3-Trimethyl-2-oxabicyclo[2.2.2]octane<br>Cineol<br>Cineole |Section1={{Chembox Identifiers | IUPHAR_ligand = 2464 | PubChem = 2758 | UNII_Ref = {{fdacite|correct|FDA}} | UNII = RV6J6604TK | KEGG_Ref = {{keggcite|correct|kegg}} | KEGG = D04115 | ChEBI = 27961 | Beilstein = 105109 5239941 | Gmelin = 131076 | EC_number = 207-431-5 | InChI = 1/C10H18O/c1-9(2)8-4-6-10(3,11-9)7-5-8/h8H,4-7H2,1-3H3 | InChIKey = WEEGYLXZBRQIMU-UHFFFAOYAY | ChEMBL_Ref = {{ebicite|correct|EBI}} | ChEMBL = 485259 | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI = 1S/C10H18O/c1-9(2)8-4-6-10(3,11-9)7-5-8/h8H,4-7H2,1-3H3 | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = WEEGYLXZBRQIMU-UHFFFAOYSA-N | CASNo_Ref = {{cascite|correct|CAS}} | CASNo = 470-82-6 | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChemSpiderID = 2656 | DrugBank_Ref = {{drugbankcite|correct|drugbank}} | DrugBank = DB03852 | SMILES = O2C1(CCC(CC1)C2(C)C)C }} |Section2={{Chembox Properties | Formula = C<sub>10</sub>H<sub>18</sub>O | MolarMass = 154.249{{nbsp}}g/mol | Density = 0.9225{{nbsp}}g/cm<sup>3</sup> | MeltingPtC = 2.9 | MeltingPt_notes = | BoilingPtC = 176–177 | BoilingPt_notes = | MagSus = {{val|-116.3e-6|u=cm<sup>3</sup>/mol}} }} |Section6={{Chembox Pharmacology | ATCCode_prefix = R05 | ATCCode_suffix = CA13 }} |Section7={{Chembox Hazards | GHSPictograms = {{GHS02}}{{GHS07}}{{GHS08}}{{GHS09}} | GHSSignalWord = Danger | HPhrases = {{H-phrases|226|304|315|317|319|411}} | PPhrases = {{P-phrases|210|233|240|241|242|243|261|264|272|273|280|301+310|302+352|303+361+353|305+351+338|321|331|332+313|333+313|337+313|362|363|370+378|391|403+235|405|501}} }} }}

'''Eucalyptol''' (also called '''cineole''') is a monoterpenoid colorless liquid, and a bicyclic ether.<ref name="pubchem">{{cite web |title=Eucalyptol |url=https://pubchem.ncbi.nlm.nih.gov/compound/2758 |publisher=PubChem, US National Library of Medicine |access-date=28 April 2023 |date=22 April 2023}}</ref> It has a fresh camphor-like odor and a spicy, cooling taste.<ref name=pubchem/> It is insoluble in water, but miscible with organic solvents. Eucalyptol makes up about 70–90% of eucalyptus oil.<ref name="wiener" /><ref>{{Cite web |title=GCMS – Gas Chromatography Mass Spectrometry Analysis |url=https://www.newdirectionsaromatics.com/msds/GC_EucalyptusRadiataEssentialOil.pdf |url-status=live |archive-url=https://web.archive.org/web/20201028145542/https://www.newdirectionsaromatics.com/msds/GC_EucalyptusRadiataEssentialOil.pdf |archive-date=28 October 2020 |access-date=7 December 2022 |website=New Direction Aromatics}}</ref> Eucalyptol forms crystalline adducts with hydrohalic acids, ''o''-cresol, resorcinol, and phosphoric acid. Formation of these adducts is useful for purification.<ref>{{Ullmann |doi=10.1002/14356007.a26_205|title=Terpenes|year= 2000|last1=Eggersdorfer|first1=Manfred}}</ref>

In 1870, F.&nbsp;S. Cloez identified and ascribed the name "eucalyptol" to the dominant portion of ''Eucalyptus globulus'' oil.<ref name=wiener>{{cite book | last1 = Boland | first1 = D. J. | last2 = Brophy | first2 = J. J. | last3 = House | first3 = A. P. N. | title = Eucalyptus Leaf Oils: Use, Chemistry, Distillation and Marketing | year = 1991 | page = 6 | isbn = 0-909605-69-6|url=https://onlinelibrary.wiley.com/doi/10.1002/ffj.2730070209| publisher = Inkata Press | location = Melbourne | doi = 10.1002/ffj.2730070209 }}</ref>

==Uses== Because of its pleasant, spicy aroma and taste, eucalyptol is used in flavorings, fragrances, and cosmetics.<ref name=pubchem/> Cineole-based eucalyptus oil is used as a flavoring at low levels (0.002%) in various products, including baked goods, confectionery, meat products, and beverages.<ref name=pubchem/><ref>{{cite book |last1=Harborne |first1=J. B. |title=Chemical Dictionary of Economic Plants |last2=Baxter |first2=H. |date=30 August 2001 |publisher=John Wiley & Sons |isbn=0-471-49226-4|url=https://books.google.com/books?id=ry11ai2iPS0C&pg=PA69}}</ref> In a 1994 report released by five top cigarette companies, eucalyptol was listed as one of the 599 additives to cigarettes.<ref>{{cite web|title=Cigarette Ingredients – Chemicals in Cigarettes|url=http://www.tricountycessation.org/tobaccofacts/Cigarette-Ingredients.html|publisher=New York State Department of Health|access-date=28 July 2014}}</ref> It is claimed to be added to improve the flavor.<ref name=pubchem/>

Eucalyptol is an ingredient in commercial mouthwashes and cough suppressants.<ref name="pubchem" />

===Other=== Eucalyptol exhibits insecticidal and insect repellent properties.<ref>{{cite journal |last1=Klocke |first1=J. A. |last2=Darlington |first2=M. V. |last3=Balandrin |first3=M. F. | title = 8-Cineole (Eucalyptol), a Mosquito Feeding and Ovipositional Repellent from Volatile Oil of ''Hemizonia fitchii'' (Asteraceae) | journal = Journal of Chemical Ecology | volume = 13 | issue = 12 |date=December 1987 | doi = 10.1007/BF01012562 |pmid=24301652 | pages = 2131–41 |bibcode=1987JCEco..13.2131K |s2cid=23271137 }}</ref><ref>{{cite journal | doi = 10.1603/033.046.0315 |last1=Sfara |first1=V. |last2=Zerba |first2=E. N. |last3=Alzogaray |first3=R. A. | title = Fumigant Insecticidal Activity and Repellent Effect of Five Essential Oils and Seven Monoterpenes on First-Instar Nymphs of ''Rhodnius prolixus'' | journal = Journal of Medical Entomology | volume = 46 | issue = 3 | pages = 511–515 |date=May 2009 | pmid = 19496421 |s2cid=23452066 |hdl=11336/82775 |hdl-access=free }}</ref>

In contrast, eucalyptol is one of many compounds that are<!--Do not change predicate to IS; the subject-pronoun THAT is plural; its antecedent is compoundS.--> attractive to males of various species of orchid bees, which gather the chemical to synthesize pheromones; it is commonly used as bait to attract and collect these bees for study.<ref>{{cite journal |last1=Schiestl |first1=F. P. |last2=Roubik |first2=D. W. |year=2004 |title=Odor Compound Detection in Male Euglossine Bees |url= |journal=Journal of Chemical Ecology |volume=29 |issue=1 |pages=253–257 |doi=10.1023/A:1021932131526 |pmid=12647866 |hdl-access=free |hdl=20.500.11850/57276 |s2cid=2845587}}</ref> One such study with ''Euglossa imperialis'', a nonsocial orchid bee species, has shown that the presence of cineole (also eucalyptol) elevates territorial behavior and specifically attracts the male bees. It was even observed that these males would periodically leave their territories to forage for chemicals such as cineole, thought to be important for attracting and mating with females, to synthesize pheromones.<ref>{{cite journal|last1=Schemske|first1=Douglas W.|first2=Russell|last2=Lande|title=Fragrance collection and territorial display by male orchid bees|journal=Animal Behaviour|volume=32|issue=3|date=1984|pages=935–937|doi=10.1016/s0003-3472(84)80184-0|s2cid=54411184}}</ref>

==Toxicology== Eucalyptol has a toxicity (LD<sub>50</sub>) of 2.48 grams per kg (rat).<ref name=pubchem/> Ingestion in significant quantities is likely to cause headache and gastric distress, such as nausea and vomiting.<ref name=pubchem/> Because of its low viscosity, it may directly enter the lungs if swallowed, or if subsequently vomited. Once in the lungs, it is difficult to remove and can cause delirium, convulsions, severe injury or death.<ref name=pubchem/>

Consequently, eucalyptol should never be ingested unless in highly diluted formulations. Toxicity is significantly reduced when administered topically. However it should not be used topically during pregnancy, breastfeeding, or on children under two.<ref>{{Cite web |title=Eucalyptus Oil: Is it Safe? |url=https://www.poison.org/articles/eucalyptus-oil |access-date=2025-05-31 |website=www.poison.org |language=en}}</ref>

== Biosynthesis == Eucalyptol is generated from geranyl pyrophosphate (GPP) which isomerizes to (''S'')-linalyl diphosphate (LPP). Ionization of the pyrophosphate, catalyzed by cineole synthase, produces eucalyptol. The process involves the intermediacy of alpha-terpinyl cation.<ref name=":0">{{Cite journal |last1=Rinkel |first1=Jan |last2=Rabe |first2=Patrick |last3=zur Horst |first3=Laura |last4=Dickschat |first4=Jeroen S |date=2016-11-04 |title=A Detailed View on 1,8-Cineol Biosynthesis by ''Streptomyces clavuligerus'' |journal=Beilstein Journal of Organic Chemistry |volume=12 |pages=2317–2324 |doi=10.3762/bjoc.12.225 |issn=1860-5397 |pmc=5238540 |pmid=28144299}}</ref><ref name=":1">{{Cite journal |last1=Wise |first1=Mitchell L. |last2=Savage |first2=Thomas J. |last3=Katahira |first3=Eva |last4=Croteau |first4=Rodney |date=1998-06-12 |title=Monoterpene Synthases From Common Sage (''Salvia Officinalis''): cDNA Isolation, Characterization, and Functional Expression of (+)-Aabinene Synthase, 1,8-Cineole Synthase, and (+)-Bo... |journal=Journal of Biological Chemistry |language=en |volume=273 |issue=24 |pages=14891–14899 |doi=10.1074/jbc.273.24.14891 |issn=0021-9258|doi-access=free |pmid=9614092 }}</ref><ref name=":2">{{Cite journal |last1=Croteau |first1=R. |last2=Alonso |first2=W. R. |last3=Koepp |first3=A. E. |last4=Johnson |first4=M. A. |date=1994-02-01 |title=Biosynthesis of Monoterpenes: Partial Purification, Characterization, and Mechanism of Action of 1,8-Cineole Synthase |url=https://www.sciencedirect.com/science/article/pii/S0003986184711015 |journal=Archives of Biochemistry and Biophysics |language=en |volume=309 |issue=1 |pages=184–192 |doi=10.1006/abbi.1994.1101 |pmid=8117108 |issn=0003-9861|url-access=subscription }}</ref> upright=2

==Plants containing eucalyptol== {{div col|colwidth=25em}} * ''Aframomum corrorima''<ref name="sibsebe">{{Cite journal | author=Sebsebe Demissew | title=A description of some essential oil bearing plants in Ethiopia and their indigenous uses | journal=Journal of Essential Oil Research | volume=5 | issue=5 | year=1993 | pages=465–479 | publisher=Taylor & Francis | doi=10.1080/10412905.1993.9698266 | quote=The chemical composition of … Aframomum corrorima (l, 8-cineole 41.9%) … is also presented.}}</ref> * ''Artemisia tridentata''<ref name=Crowell2018>{{cite journal |author= Crowell, M.M.|display-authors=etal|title=Dietary partitioning of toxic leaves and fibrous stems differs between sympatric specialist and generalist mammalian herbivores|journal=Journal of Mammalogy |volume=99 |issue=3 |pages=565–577 |year=2018 |doi=10.1093/jmammal/gyy018|doi-access=free }}</ref> * ''Cannabis''<ref name="mcpartland2001">{{cite journal |last1=McPartland |first1=J. M. |last2=Russo |first2=E. B. |title=Cannabis and cannabis extracts: greater than the sum of their parts? |journal=Journal of Cannabis Therapeutics |volume=1 |issue=3–4 |pages=103–132 |year=2001 |doi=10.1300/J175v01n03_08 |url=http://www.cannabis-med.org/index.php?tpl=journal&id=228&lng=en&fid=2001:3/4&red=journallist |access-date=20 September 2013 |url-access=subscription |archive-date=21 September 2013 |archive-url=https://web.archive.org/web/20130921060942/http://www.cannabis-med.org/index.php?tpl=journal&id=228&lng=en&fid=2001:3/4&red=journallist |url-status=dead }}</ref> * ''Cinnamomum camphora'', camphor laurel (50%)<ref>{{cite journal |last1=Stubbs |first1=B. J. |last2=Brushett |first2=D. | title = Leaf oil of ''Cinnamomum camphora'' (L.) Nees and Eberm. From Eastern Australia | journal = Journal of Essential Oil Research | volume = 13 | issue = 1 | pages = 51–54 | year = 2001 | doi=10.1080/10412905.2001.9699604|s2cid=85418932 }}</ref> * ''Eucalyptus globulus''<ref>{{cite journal |last1=Maciel |first1=M. V. |last2=Morais |first2=S. M. |last3=Bevilaqua |first3=C. M. |last4=Silva |first4=R. A. |last5=Barros |first5=R. S. |last6=Sousa |first6=R. N. |last7=Sousa |first7=L. C. |last8=Brito |first8=E. S. |last9=Souza Neto |first9=M. A. | year = 2010 | title = Chemical composition of ''Eucalyptus'' spp. essential oils and their insecticidal effects on ''Lutzomyia longipalpis'' | journal = Veterinary Parasitology | volume = 167 | issue = 1 | pages = 1–7 | doi = 10.1016/j.vetpar.2009.09.053 | pmid = 19896276 |s2cid=7665066 |url=https://ainfo.cnptia.embrapa.br/digital/bitstream/item/34137/1/PA10006.pdf }}</ref> * ''Eucalyptus largiflorens''<ref>{{cite journal|title=Chemistry and bioactivity of Eucalyptus essential oils|volume= 25|issue=2|pages=313–330|year=2010 |journal= Allelopathy Journal|url=https://researchoutput.csu.edu.au/ws/portalfiles/portal/8780096/Zhang+et+al+2010.pdf|vauthors=Zhang J, An M, Wu H, Stanton R, Lemerle D}}</ref> * ''Eucalyptus salmonophloia''<ref name=Gardner>{{cite journal|url=https://library.dpird.wa.gov.au/cgi/viewcontent.cgi?article=1089&context=journal_agriculture3|title=Trees of Western Australia - salmon gum and scarlet pear gum|accessdate=23 January 2023|journal=Journal of the Department of Agriculture Western Australia |series=Series 3|author=Charles Austin Gardner|volume=1|number=4|date=1 August 1952|publisher=Department of Primary Industries and Regional Development}}</ref> * ''Eucalyptus staigeriana''<ref>{{cite journal | last1 = Gilles | first1 = M. | last2 = Zhao | first2 = J. | last3 = An | first3 = M. | last4 = Agboola | first4 = S. | year = 2010 | title = Chemical Composition and Antimicrobial Properties of Essential Oils of three Australian ''Eucalyptus'' Species | journal = Food Chemistry | volume = 119 | issue = 2 | pages = 731–737 | doi = 10.1016/j.foodchem.2009.07.021 }}</ref> * ''Eucalyptus wandoo''<ref name=2021study>{{cite journal|title=Chemical composition of essential oils of eight Tunisian Eucalyptus species and their antibacterial activity against strains responsible for otitis|last1=Ameur|first1=Elaissi|last2=Sarra|first2=Moumni|last3=Yosra|first3=Derbali|last4=Mariem|first4=Kouja|last5=Nabil|first5=Abid|last6=Lynen|first6=Frederic|last7=Larbi|first7=Khouja Mohamed|journal=BMC Complement Med Ther|volume=21|year=2021|issue=1 |page=209 |doi=10.1186/s12906-021-03379-y|pmid=34384412 |pmc=8359536 |doi-access=free }}</ref> * ''Hedychium coronarium'', butterfly lily<ref>{{cite journal|last1=Ali |first1=S. |last2=Sotheeswaran |first2=S. |last3=Tuiwawa |first3=M. |last4=Smith |first4=R. |date=2002 |title=Comparison of the Composition of the Essential Oils of ''Alpinia'' and ''Hedychium'' Species—Essential Oils of Fijian Plants, Part 1 |journal=Journal of Essential Oil Research |volume=14 |issue=6 |pages=409–411 |doi=10.1080/10412905.2002.9699904|s2cid=95463805 }}</ref><ref>{{cite journal|last1=Joy |first1=B. |last2=Rajan |first2=A. |last3=Abraham |first3=E. |date=2007 |title=Antimicrobial Activity and Chemical Composition of Essential Oil from ''Hedychium coronarium'' |journal=Phytotherapy Research |volume=21 |issue=5 |pages=439–443 |doi=10.1002/ptr.2091|pmid=17245683 |s2cid=27756399 }}</ref> * ''Helichrysum gymnocephalum''<ref>{{Cite journal | last1 = Möllenbeck | first1 = S. | last2 = König | first2 = T. | last3 = Schreier | first3 = P. | last4 = Schwab | first4 = W. | last5 = Rajaonarivony | first5 = J. | last6 = Ranarivelo | first6 = L. | doi = 10.1002/(SICI)1099-1026(199703)12:2<63::AID-FFJ614>3.0.CO;2-Z | title = Chemical Composition and Analyses of Enantiomers of Essential Oils from Madagascar | journal = Flavour and Fragrance Journal | volume = 12 | issue = 2 | pages = 63 | year = 1997 }}</ref> * ''Kaempferia galanga'', galangal, (5.7%)<ref name=ceor>{{cite journal | last1 = Wong | first1 = K. C. | last2 = Ong | first2 = K. S. | last3 = Lim | first3 = C. L. | title = Composition of the Essential Oil of Rhizomes of ''Kaempferia galanga'' L. | journal = Flavour and Fragrance Journal | volume = 7 | issue = 5 | pages = 263–266 | year = 2006 | doi = 10.1002/ffj.2730070506 }}</ref> * ''S.&nbsp;officinalis'' subsp. ''lavandulifolia'' (syn. ''S.&nbsp;lavandulifolia''), Spanish sage (13%)<ref name="perry2000">{{cite journal |last1=Perry |first1=N. S. |last2=Houghton |first2=P. J. |last3=Theobald |first3=A. |last4=Jenner |first4=P. |last5=Perry |first5=E. K. |title=In-vitro inhibition of human erythrocyte acetylcholinesterase by ''Salvia lavandulaefolia'' essential oil and constituent terpenes |journal=J Pharm Pharmacol |volume=52 |issue=7 |pages=895–902 |year=2000 |doi=10.1211/0022357001774598 |pmid=10933142|s2cid=34457692 |doi-access=free }}</ref> * ''Salvia rosmarinus'', rosemary<ref>{{Cite journal |last=Jiang |first=Yang |last2=Wu |first2=Nan |last3=Fu |first3=Yu-Jie |last4=Wang |first4=Wei |last5=Luo |first5=Meng |last6=Zhao |first6=Chun-Jian |last7=Zu |first7=Yuan-Gang |last8=Liu |first8=Xiao-Lei |date=2011-07-01 |title=Chemical composition and antimicrobial activity of the essential oil of Rosemary |url=https://linkinghub.elsevier.com/retrieve/pii/S1382668911000469 |journal=Environmental Toxicology and Pharmacology |volume=32 |issue=1 |pages=63–68 |doi=10.1016/j.etap.2011.03.011 |issn=1382-6689|url-access=subscription }}</ref> * ''Turnera diffusa'', damiana<ref>{{cite book | last = Balch | first = P. A. | year = 2002 | title = Prescription for Nutritional Healing: the A to Z Guide to Supplements | publisher = Penguin | page = [https://archive.org/details/prescriptionfor000balc/page/233 233] | isbn = 978-1-58333-143-9 | url-access = registration | url = https://archive.org/details/prescriptionfor000balc/page/233 }}</ref> * ''Umbellularia californica'', pepperwood (22.0%)<ref>{{cite journal |last1=Kelsey |first1=R. G. |last2=McCuistion |first2=O. |last3=Karchesy |first3=J. | title = Bark and Leaf Essential Oil of ''Umbellularia californica'', California Bay Laurel, from Oregon | journal = Natural Product Communications | volume = 2 | issue = 7 | year = 2007 | pages = 779–780 |doi=10.1177/1934578X0700200715 |doi-access=free }}</ref> * ''Zingiber officinale'', ginger<ref name="pmid21366054">{{cite journal |vauthors=Gupta S, Pandotra P, Ram G, Anand R, Gupta AP, Husain K, Bedi YS, Mallavarapu GR |title=Composition of a monoterpenoid-rich essential oil from the rhizome of Zingiber officinale from north western Himalayas |journal=Natural Product Communications |volume=6 |issue=1 |pages=93–6 |date=January 2011 |doi=10.1177/1934578X1100600122 |pmid=21366054 |s2cid=20981360 |doi-access=free }}</ref> {{div col end}}

==See also== * Camphor * Citral * Eucalyptus oil * Lavandula * Menthol * Mouthwash

== References == {{Reflist}}

{{Non-timber forest products}} {{Transient receptor potential channel modulators}}

Category:Cooling flavors Category:Monoterpenes Category:Ethers Category:Tree-derived bioactive compounds