Myrcene

File:MyrceneBiosyn.svg.]]

Myrcene is often produced commercially by the pyrolysis (400 °C) of β-pinene, which is obtained from turpentine. It is rarely obtained directly from plants.{{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}}

Plants biosynthesize myrcene via geranyl pyrophosphate (GPP), which isomerizes into linalyl pyrophosphate. An elimination reaction, releasing the pyrophosphate (OPP) and a proton, completes the conversion.{{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}}

It could in principle be extracted from any number of plants, such as verbena or wild thyme, 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. Some of these include cannabis,{{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 }} hops, Houttuynia, lemon grass, mango, Myrcia, West Indian bay tree, and cardamom.{{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}}

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.{{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}} 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.{{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}}

It is found in the South African Adenandra villosa (50%).{{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.}} & Brazilian Schinus molle (40%){{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 }} Myrcene is also found in Myrcia cuprea petitgrain (up to 48%),{{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 }} bay leaf, juniper berry, cannabis, and hops.{{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}}

Myrcene is an intermediate used in the perfumery industry. It has a pleasant odor but is rarely used directly. It is also unstable in air, tending to polymerize. 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.

Both myrcene and myrcenol undergo Diels–Alder reactions with several dienophiles, such as acrolein, to give cyclohexene derivatives that are also useful fragrances, for instance Lyral.{{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}}

Myrcene also contributes a peppery and balsam aroma in beer.{{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}}{{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 }}

As of October 2018, the 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.{{Federal Register|83|50490}}

In 2015, beta-myrcene was added to California's Prop 65 list of chemicals known to the state of California to cause cancer or reproductive harm.{{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}}

• Perfume allergy

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Category:Flavors

Category:Polyenes

Category:Perfume ingredients

Category:Monoterpenes

Category:Wood extracts