Myrcene: Difference between revisions

{{this|β-myrcene|its isomer|α-Myrcene}}

| Verifiedfields = changed

| Watchedfields = changed

| verifiedrevid = 415853613

| Reference =<ref>''[[Merck Index]]'', 11th Edition, '''6243'''</ref>

| Name = Myrcene

| ImageFile = Myrcene beta straight acsv.svg

| ImageSize = 220px

| ImageName = Beta-myrcene, skeletal formula

| ImageFile1 = Beta-Myrcene molecule ball.png

| ImageSize1 = 230px

| ImageName1 = Ball-and-stick model of the beta-myrcene molecule

| PIN = 7-Methyl-3-methylideneocta-1,6-diene

|Section1={{Chembox Identifiers

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| KEGG_Ref = {{keggcite|correct|kegg}}

| ChEMBL_Ref = {{ebicite|correct|EBI}}

| CASNo = 123-35-3

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = 3M39CZS25B

| ChEBI_Ref = {{ebicite|changed|EBI}}

| ChEBI = 17221

| SMILES = CC(=CCCC(=C)C=C)C

|Section2={{Chembox Properties

| C=10 | H=16

| Density = 0.794 g/cm³

| MeltingPt= <

| MeltingPtC = -10

| BoilingPtC = 166 to 168

| BoilingPt_ref = <ref name=Ullmann/><!-- Index of refraction for myrcene 1.4697 according to Ullmann's-->

}}

'''Myrcene''', or '''β-myrcene''', is a [[terpene|monoterpene]]. A colorless oil, it occurs widely in [[essential oil]]s. It is produced mainly semi-synthetically from ''[[Myrcia]]'', from which it gets its name. It is an intermediate in the production of several fragrances.<ref name=Behr>{{cite journal |author1=Behr, A. |author2=Johnen, L.| title = Myrcene as a Natural Base Chemical in Sustainable Chemistry: A Critical Review | journal = ChemSusChem | year = 2009 | volume = 2 | issue = 12 | pages = 1072–1095 | doi = 10.1002/cssc.200900186 | pmid=20013989|bibcode=2009ChSCh...2.1072B }}</ref> An less-common [[isomer]]ic form, having one of the three [[alkene]] units in a different position, is [[α-myrcene]].

==Production==

[[File:MyrceneBiosyn.svg|thumb|244 px|left|Biosynthesis of myrcene from [[geranyl pyrophosphate]].]]

Myrcene is often produced commercially by the [[pyrolysis]] (400&nbsp;°C) of β-[[pinene]], which is obtained from [[turpentine]].<ref name=Behr/> It is rarely obtained directly from plants.<ref name=UllmannEgg>{{cite encyclopedia|author=M. Eggersdorfer |title=Terpenes|encyclopedia=Ullmann's Encyclopedia of Industrial Chemistry|year=2005|publisher=Wiley-VCH|place=Weinheim|doi=10.1002/14356007.a26_205|isbn=3-527-30673-0}}</ref>

Plants biosynthesize myrcene via [[geranyl pyrophosphate]] (GPP), which isomerizes into [[linalool|linalyl]] pyrophosphate. An [[elimination reaction]], releasing the [[pyrophosphate]] (OPP) and a proton, completes the conversion.<ref>{{Cite book|title=Medicinal Natural Products: A Biosynthetic Approach|last=Dewick|first=Paul M.|publisher=John Wiley and Sons, Ltd.|year=2002|isbn=0-471-49641-3|location=New York|page=174|url=https://books.google.com/books?id=A4zptjOJfKQC}}</ref>

==Occurrence==

It could in principle be extracted from any number of plants, such as [[verbena]] or [[wild thyme]],<ref name=UllmannEgg/> the leaves of which contain up to 40% by weight of myrcene.{{cn|date=September 2021}} Many other plants contain myrcene, sometimes in substantial amounts.<ref name=Behr/> Some of these include cannabis,<ref name="Booth">{{cite journal | last1=Booth | first1=Judith K. | last2=Page | first2=Jonathan E. | last3=Bohlmann | first3=Jörg | editor-last=Hamberger | editor-first=Björn | title=Terpene synthases from ''Cannabis sativa'' | journal=PLOS ONE| volume=12 | issue=3 | date=29 March 2017 | issn=1932-6203 | doi=10.1371/journal.pone.0173911 | page=e0173911|pmid=28355238|pmc=5371325| bibcode=2017PLoSO..1273911B | doi-access=free }}</ref> hops, ''[[Houttuynia]]'', [[lemon grass]], [[mango]], ''Myrcia'', [[West Indian bay tree]], and [[cardamom]].<ref>{{cite journal|pmid=15453700|year=2004|last1=Marongiu|first1=B|title=Comparative analysis of the oil and supercritical CO2 extract of ''Elettaria cardamomum'' (L.) Maton|journal=Journal of Agricultural and Food Chemistry|volume=52|issue=20|pages=6278–82|last2=Piras|first2=A|last3=Porcedda|first3=S|doi=10.1021/jf034819i}}</ref>

Of the several terpenes extracted from ''[[Humulus lupulus]]'' (hops), the largest monoterpenes fraction is β-myrcene. One study of the chemical composition of the fragrance of ''[[Cannabis sativa]]'' found β-myrcene to compose between 29.4% and 65.8% of the steam-distilled essential oil for the set of fiber and drug strains tested.<ref>{{Cite web|url=http://druglibrary.net/olsen/HEMP/IHA/jiha4208.html|title=Essential oil of ''Cannabis sativa'' L. strains|website=druglibrary.net|access-date=2017-06-08}}</ref> Additionally, myrcene is thought to be the predominant terpene found in modern cannabis cultivars within North America. Interestingly, photo-oxidation of myrcene has been shown to rearrange the molecule into a novel terpene known as "hashishene" which is named for its abundance in hashish.<ref>{{Cite web|title=Myrcene Terpene for Extracts, vape and concentrates|url=https://www.elevationterpenes.com/products/myrcene-terpene-for-extracts-vape-and-concentrates|access-date=2020-12-03|website=ElevationTerpenes}}</ref>

It is found in the South African ''[[Adenandra|Adenandra villosa]]'' (50%).<ref>{{Cite journal|url=https://agris.fao.org/agris-search/search.do?recordID=US201301099695|title = Composition of the essential oils of two Adenandra species from South Africa|journal = Journal of Essential Oil Research |year = 2006|last1 = Baser|first1 = K. H. C.|last2 = Demirci|first2 = B.|last3 = Ozek|first3 = T.|last4 = Viljoen|first4 = A. M.|last5 = Victor|first5 = J. E.}}</ref> & Brazilian ''[[Schinus molle]]'' (40%)<ref>{{cite journal |doi=10.1016/j.foodcont.2018.07.034|title=Essential oil from pink pepper (Schinus terebinthifolius Raddi): Chemical composition, antibacterial activity and mechanism of action |year=2019 |last1=Dannenberg |first1=Guilherme da Silva |last2=Funck |first2=Graciele Daiana |last3=Silva |first3=Wladimir Padilha da |last4=Fiorentini |first4=Ângela Maria |journal=Food Control |volume=95 |pages=115–120 |s2cid=92548775 }}</ref> Myrcene is also found in ''[[Myrcia|Myrcia cuprea]]'' [[petitgrain]] (up to 48%),<ref>{{cite journal|doi=10.1002/ffj.1242|title=Essential oils from three ''Myrcia'' species |year=2003 |last1=Zoghbi |first1=M das Graças B. |last2=Andrade |first2=Eloisa Helena A. |last3=Da Silva |first3=Milton Helio L. |last4=Carreira |first4=L. M. M. |last5=Maia |first5=J. G. S. |journal=Flavour and Fragrance Journal |volume=18 |issue=5 |pages=421–424 }}</ref> [[bay leaf]], [[juniper berry]], [[cannabis]], and [[hops]].<ref name=Behr/><ref name=csoc>{{cite journal | last1 = Chyau | first1 = C.-C. | last2 = Mau | first2 = J.-L. | last3 = Wu | first3 = C.-M. | title = Characteristics of the Steam-Distilled Oil and Carbon Dioxide Extract of ''Zanthoxylum simulans'' Fruits | journal = [[Journal of Agricultural and Food Chemistry]] | year = 1996 | volume = 44 | issue = 4 | pages = 1096–1099 | doi = 10.1021/jf950577d}}</ref>

==Use in fragrance and flavor industries==

Myrcene is an intermediate used in the [[perfumery]] industry. It has a pleasant odor but is rarely used directly.<ref name=Behr/> It is also unstable in air, tending to [[polymer]]ize. Samples are stabilized by the addition of alkylphenols or [[tocopherol]]. It is thus more highly valued as an intermediate for the preparation of flavor and fragrance chemicals, such as [[menthol]], [[citral]], [[citronellol]], [[citronellal]], [[geraniol]], [[nerol]], and [[linalool]].<ref name=UllmannEgg/>

Both myrcene and myrcenol undergo [[Diels–Alder reaction]]s with several [[dienophile]]s, such as [[acrolein]], to give [[cyclohexene]] derivatives that are also useful fragrances, for instance [[Lyral]].<ref name=Ullmann>{{cite encyclopedia |author1=Fahlbusch, K.-G. |author2=Hammerschmidt, F.-J. |author3=Panten, J. |author4=Pickenhagen, W. |author5=Schatkowski, D. |author6=Bauer, K. |author7=Garbe, D. |author8=Surburg, H. | encyclopedia = Ullmann's Encyclopedia of Industrial Chemistry | year = 2002 | publisher = Wiley-VCH | location = Weinheim | doi = 10.1002/14356007.a11_141 |chapter=Flavors and Fragrances |isbn=3-527-30673-0}}</ref>

Myrcene also contributes a peppery and balsam aroma in beer.<ref>{{cite journal|pmid=23627300|year=2013|last1=Inui|first1=T|title=Different beers with different hops. Relevant compounds for their aroma characteristics|journal=Journal of Agricultural and Food Chemistry|volume=61|issue=20|pages=4758–64|last2=Tsuchiya|first2=F|last3=Ishimaru|first3=M|last4=Oka|first4=K|last5=Komura|first5=H|doi=10.1021/jf3053737}}</ref><ref>{{cite journal|pmid=23483584|year=2013|last1=Vázquez Araújo|first1=L.|title=Use of hydrodistillation and headspace solid-phase microextraction to characterize the volatile composition of different hop cultivars|journal=Journal of the Science of Food and Agriculture|volume=93|issue=10|pages=2568–74|last2=Rodríguez Solana|first2=R|last3=Cortés Diéguez|first3=S. M.|last4=Domínguez|first4=J. M.|doi=10.1002/jsfa.6078|bibcode=2013JSFA...93.2568V }}</ref>

As of October 2018, the [[Food and Drug Administration|U.S. FDA]] withdrew authorization for the use of myrcene as a synthetic flavoring substance for use in food, without regard to its continuing stance that this substance does not pose a risk to public health under the conditions of its intended use.<ref>{{Federal Register|83|50490}}</ref>

== Health and safety ==

In 2015, beta-myrcene was added to [[1986 California Proposition 65|California's Prop 65]] list of chemicals known to the state of California to cause cancer or reproductive harm.<ref>{{cite web |title=Proposition 65 |url=https://oehha.ca.gov/proposition-65/chemicals/beta-myrcene |website=oehha.ca.gov |publisher=OEHHA - California Office of Environmental Health Hazard Assessment}}</ref>

== References ==

{{reflist}}

[[Category:Polyenes]]

[[Category:Wood extracts]]