Myrcene Biosynthesis.png
   HOME

TheInfoList



OR:

Myrcene, or β-myrcene, is a monoterpene. A colorless oil, it occurs widely in
essential oil An essential oil is a concentrated hydrophobic liquid containing volatile (easily evaporated at normal temperatures) chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the o ...
s. It is produced mainly semi-synthetically from ''
Myrcia ''Myrcia'' is a genus of plants in the family Myrtaceae, containing about 765 species as of 2022. They are distributed in Central and South America, Mexico, and the Caribbean, with centers of diversity in the Brazilian Cerrado and Atlantic Forest ...
'', from which it gets its name. It is an intermediate in the production of several fragrances. α-Myrcene is the name for the
isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Iso ...
2-methyl-6-methylene-1,7-octadiene, which has not been found in nature.


Production

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. Plants biosynthesize myrcene via geranyl pyrophosphate (GPP), which isomerizes into linalyl pyrophosphate. The release of the pyrophosphate (OPP) and a proton completes the conversion.


Occurrence

It could in principle be extracted from any number of plants, such as
verbena ''Verbena'' (), also known as vervain or verveine, is a genus in the family Verbenaceae. It contains about 150 species of annual and perennial herbaceous or semi-woody flowering plants. The majority of the species are native to the Americas a ...
or wild thyme, the leaves of which contain up to 40% by weight of myrcene. Many other plants contain myrcene, sometimes in substantial amounts. Some of these include cannabis, hops, ''
Houttuynia ''Houttuynia'' is a genus of two species in the Saururaceae native to Southeast Asia. One species, '' H. cordata'', is widely cultivated as a culinary herb. The genus was originally described in 1783 by Carl Peter Thunberg when he formally d ...
'', lemon grass,
mango A mango is an edible stone fruit produced by the tropical tree ''Mangifera indica''. It is believed to have originated in the region between northwestern Myanmar, Bangladesh, and northeastern India. ''M. indica'' has been cultivated in South a ...
, ''Myrcia'',
West Indian bay tree ''Pimenta racemosa'' is a species of plant in the myrtle family (Myrtaceae) that is native to the Caribbean region. Common names include West Indian bay tree, bay rum tree, and ciliment. It is used in cooking and an essential oil is distilled to ...
, and cardamom. 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. 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. It is found in the South African ''Adenandra, Adenandra villosa'' (50%). & Brazilian ''Schinus molle'' (40%) Myrcene is also found in ''Myrcia, Myrcia cuprea'' petitgrain (up to 48%), bay leaf, bay leaf, juniper berry, cannabis, and hops.


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. 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. Myrcene is converted to myrcenol, another fragrance found in lavender, via hydroamination of the 1,3-diene by diethylamine followed by hydrolysis and palladium-catalyzed removal of the amine. 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. Myrcene also contributes a peppery and balsam aroma in beer. 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.


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.


See also

* Perfume allergy


References

{{reflist Flavors Polyenes Perfume ingredients Monoterpenes