Myrcene, or β-myrcene, is a monoterpene. A colorless oil, it occurs widely in essential oils. It is produced mainly semi-synthetically from Myrcia, from which it gets its name. It is an intermediate in the production of several fragrances.[3] An less-common isomeric form, having one of the three alkene units in a different position, is α-myrcene.
Myrcene is often produced commercially by the pyrolysis (400 °C) of β-pinene, which is obtained from turpentine.[3] It is rarely obtained directly from plants.[4]
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.[8] 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.[9]
Myrcene is an intermediate used in the perfumery industry. It has a pleasant odor but is rarely used directly.[3] 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.[4]
Myrcene also contributes a peppery and balsam aroma in beer.[14][15]
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.[16]
Health and safety
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.[17]
^Marongiu, B; Piras, A; Porcedda, S (2004). "Comparative analysis of the oil and supercritical CO2 extract of Elettaria cardamomum (L.) Maton". Journal of Agricultural and Food Chemistry. 52 (20): 6278–82. doi:10.1021/jf034819i. PMID15453700.
^Dannenberg, Guilherme da Silva; Funck, Graciele Daiana; Silva, Wladimir Padilha da; Fiorentini, Ângela Maria (2019). "Essential oil from pink pepper (Schinus terebinthifolius Raddi): Chemical composition, antibacterial activity and mechanism of action". Food Control. 95: 115–120. doi:10.1016/j.foodcont.2018.07.034. S2CID92548775.
^Zoghbi, M das Graças B.; Andrade, Eloisa Helena A.; Da Silva, Milton Helio L.; Carreira, L. M. M.; Maia, J. G. S. (2003). "Essential oils from three Myrcia species". Flavour and Fragrance Journal. 18 (5): 421–424. doi:10.1002/ffj.1242.
^Inui, T; Tsuchiya, F; Ishimaru, M; Oka, K; Komura, H (2013). "Different beers with different hops. Relevant compounds for their aroma characteristics". Journal of Agricultural and Food Chemistry. 61 (20): 4758–64. doi:10.1021/jf3053737. PMID23627300.
^Vázquez Araújo, L.; Rodríguez Solana, R; Cortés Diéguez, S. M.; Domínguez, J. M. (2013). "Use of hydrodistillation and headspace solid-phase microextraction to characterize the volatile composition of different hop cultivars". Journal of the Science of Food and Agriculture. 93 (10): 2568–74. Bibcode:2013JSFA...93.2568V. doi:10.1002/jsfa.6078. PMID23483584.
