Jump to content

Monoterpene

From Wikipedia, the free encyclopedia

Monoterpenesare a class ofterpenesthat consist of twoisopreneunits and have the molecular formula C10H16.Monoterpenes may be linear (acyclic) or contain rings (monocyclic and bicyclic). Modified terpenes, such as those containing oxygen functionality or missing a methyl group, are calledmonoterpenoids.Monoterpenes and monoterpenoids are diverse. They have relevance to the pharmaceutical, cosmetic, agricultural, and food industries.[1]

Biosynthesis[edit]

Main article:Terpene § Biosynthesis

Monoterpenes are derived biosynthetically from units ofisopentenyl pyrophosphate,which is formed fromacetyl-CoAvia the intermediacy ofmevalonic acidin theHMG-CoA reductase pathway.An alternative, unrelated biosynthesis pathway of IPP is known in some bacterial groups and the plastids of plants, the so-called MEP-(2-methyl-D-erythritol-4-phosphate) pathway, which is initiated fromC5sugars.In both pathways, IPP is isomerized to DMAPP by the enzyme isopentenyl pyrophosphate isomerase.

Geranyl pyrophosphate is the precursor to monoterpenes (and hence monoterpenoids).[2] Elimination of the pyrophosphate group from geranyl pyrophosphate leads to the formation of acyclic monoterpenes such asocimeneand themyrcenes.Hydrolysis of the phosphate groups leads to the prototypical acyclic monoterpenoidgeraniol.Additional rearrangements and oxidations provide compounds such ascitral,citronellal,citronellol,linalool,and many others. Many monoterpenes found in marine organisms arehalogenated,such ashalomon.

Main examples[edit]

Bicyclic monoterpenes includecarene,sabinene,camphene,andthujene.Camphor,borneol,eucalyptolandascaridoleare examples of bicyclic monoterpenoids containing ketone, alcohol, ether, and bridgingperoxidefunctional groups, respectively.[3][4]Umbelluloneis another example of bicyclic monoterpene ketone.

Natural roles[edit]

Monoterpenes are found in many parts of different plants, such asbarks,heartwood,bark and leaves of coniferous trees, invegetables,fruitsandherbs.[5]Essential oilsare very rich in monoterpenes. Several monoterpenes produced by trees, such aslinalool,hinokitiol,andocimenehavefungicidalandantibacterialactivities and participate in wound healing.[6]Some of these compounds are produced to protect the trees frominsectattacks.

Monoterpenes are emitted byforestsand formaerosolsthat are proposed to serve ascloud condensation nuclei(CCN). Such aerosols can increase the brightness of clouds and cool the climate.[7]

Many monoterpenes have unique smell and flavor. For example,sabinenecontributes to thespicytaste ofblack pepper,3-carenegivescannabisan earthy taste and smell,citralhas a lemon-like pleasant odor and contributes to the distinctive smell ofcitrusfruits, andthujeneandcarvacrolare responsible for thepungentflavors ofsummer savoryandoregano,respectively.[8][9][10]

Monoterpenes are consideredallelochemicals.[11]

Uses[edit]

Many monoterpenes arevolatilecompounds and some of them are well-knownfragrantsfound in theessential oilsof many plants.[12]For example,camphor,citral,citronellol,geraniol,grapefruit mercaptan,eucalyptol,ocimene,myrcene,limonene,linalool,menthol,campheneandpinenesare used inperfumesandcosmeticproducts.Limoneneandperillyl alcoholare used incleaningproducts.[13][14]

Many monoterpenes are used as foodflavorsandfood additives,such asbornyl acetate,citral,eucalyptol,menthol,hinokitiol,campheneandlimonene.[15][16]Menthol,hinokitiolandthymolare also used inoral hygieneproducts.Thymolalso hasantisepticanddisinfectantproperties.[17]

Volatile monoterpenes produced by plants can attract or repel insects, thus some of them are used ininsect repellents,such ascitronellol,eucalyptol,limonene,linalool,hinokitiol,mentholandthymol.[16]

Ascaridole,camphorandeucalyptolare monoterpenes that have pharmaceutical use.[18][19]

Health effects[edit]

A study suggests that a range offloor cleanerswith certain monoterpenes may cause indoorair pollutionequivalent or exceeding the harm to respiratory tracts when the time is spentnear a busy road.This is due toozonolysisof monoterpenes likeLimoneneleading to the production of atmosphericSOA.[20][21]Another study suggests monoterpenes substantially affect ambient organic aerosol with uncertainties regarding environmental impacts.[22]In a review, scientists concluded that they hope that these "substances will be extensively studied and used in more and more in medicine".[23]A 2013 study found that "Based on adverse effects and risk assessments, d-limonene may be regarded as a safe ingredient. However, the potential occurrence of skin irritation necessitates regulation of this chemical as an ingredient in cosmetics."[24][better source needed]According to a review, several studies showed "that some monoterpenes (e.g., pulegone, menthofuran, camphor, and limonene) and sesquiterpenes (e.g., zederone, germacrone) exhibited liver toxicity" and that i.a. intensive research on terpenes toxicity is needed.[25]

See also[edit]

References[edit]

  1. ^Eberhard Breitmaier (2006). "Hemi‐ and Monoterpenes".Terpenes: Flavors, Fragrances, Pharmaca, Pheromones.pp. 10–23.doi:10.1002/9783527609949.ch2.ISBN9783527609949.
  2. ^Davis, Edward M.; Croteau, Rodney (2000). "Cyclization enzymes in the biosynthesis of monoterpenes, sesquiterpenes, and diterpenes".Topics in Current Chemistry.209:53–95.doi:10.1007/3-540-48146-X_2.ISBN978-3-540-66573-1.
  3. ^Brown, R.T. (1975). "Bicyclic Monoterpenoids".Supplements to the 2nd Edition of Rodd's Chemistry of Carbon Compounds:53–93.doi:10.1016/B978-044453346-3.50098-6.ISBN9780444533463.
  4. ^Vil’, Vera; Yaremenko, Ivan; Ilovaisky, Alexey; Terent’ev, Alexander (2 November 2017)."Peroxides with Anthelmintic, Antiprotozoal, Fungicidal and Antiviral Bioactivity: Properties, Synthesis and Reactions".Molecules.22(11): 1881.doi:10.3390/molecules22111881.PMC6150334.PMID29099089.
  5. ^Sjöström, Eero (22 October 2013). "Chapter 5: Extractives".Wood Chemistry: Fundamentals and Applications(Second ed.). San Diego.ISBN978-0-08-092589-9.{{cite book}}:CS1 maint: location missing publisher (link)
  6. ^Rowell, Roger M. (2013). "Chater 3: Cell Wall Chemistry".Handbook of Wood Chemistry and Wood Composites(2nd ed.). Boca Raton: Taylor & Francis.ISBN9781439853801.
  7. ^D. V. Spracklen; B. Bonn; K. S. Carslaw (2008)."Boreal forests, aerosols and the impacts on clouds and climate"(PDF).Philosophical Transactions of the Royal Society A.366(1885): 4613–26.Bibcode:2008RSPTA.366.4613S.doi:10.1098/rsta.2008.0201.PMID18826917.S2CID206156442.
  8. ^Tamer, Canan Ece; Suna, Senem; Özcan-Sinir, Gülşah (2019)."14 - Toxicological Aspects of Ingredients Used in Nonalcoholic Beverages".Non-alcoholic beverages. Volume 6: The Science of Beverages.Duxford, United Kingdom: Woodhead Publishing. pp. 441–481.doi:10.1016/B978-0-12-815270-6.00014-1.ISBN978-0-12-815270-6.S2CID187341441.
  9. ^PDR for herbal medicines(4th ed.). Montvale, NJ: Thomson. 2007. p. 802.ISBN978-1-56363-512-0.
  10. ^"Herbs of the Labiatae".Encyclopedia of food sciences and nutrition(2nd ed.). Amsterdam: Academic Press. 2003. pp. 3082–3090.doi:10.1016/B0-12-227055-X/00593-9.ISBN978-0-12-227055-0.
  11. ^Saeidnia, Soodabeh; Gohari, Ahmad Reza (2012). "Trypanocidal Monoterpenes".Studies in Natural Products Chemistry.37:173–190.doi:10.1016/B978-0-444-59514-0.00006-7.ISBN9780444595140.
  12. ^Loza-Tavera, Herminia (1999). "Monoterpenes in Essential Oils".Chemicals via Higher Plant Bioengineering.Advances in Experimental Medicine and Biology. Vol. 464. pp. 49–62.doi:10.1007/978-1-4615-4729-7_5.ISBN978-1-4613-7143-4.PMID10335385.
  13. ^"Limonene".pubchem.ncbi.nlm.nih.gov.
  14. ^Laszlo, Pierre (2007).Citrus: A history.Chicago: University of Chicago Press.ISBN9780226470283.
  15. ^Caputi, Lorenzo; Aprea, Eugenio (1 January 2011). "Use of Terpenoids as Natural Flavouring Compounds in Food Industry".Recent Patents on Food, Nutrition & Agriculture.3(1): 9–16.doi:10.2174/2212798411103010009.PMID21114471.
  16. ^abComprehensive natural products chemistry(1st ed.). Amsterdam: Elsevier. 1999. p. 306.ISBN978-0-08-091283-7.
  17. ^"R.E.D. FACTS: Thymol"(PDF).United States Environmental Protection Agency.
  18. ^"Camphor Cream and Ointment Information".Drugs.
  19. ^Tisserand, Robert (2014)."Chapter 13: Essential oil profiles".Essential oil safety: a guide for health care professionals(Second ed.). Edinburgh: Churchill Livingstone.ISBN978-0-443-06241-4.
  20. ^"Cleaning products cause indoor pollution levels similar to a busy road".New Scientist.Retrieved10 March2022.
  21. ^Rosales, Colleen Marciel F.; Jiang, Jinglin; Lahib, Ahmad; Bottorff, Brandon P.; Reidy, Emily K.; Kumar, Vinay; Tasoglou, Antonios; Huber, Heinz; Dusanter, Sebastien; Tomas, Alexandre; Boor, Brandon E.; Stevens, Philip S. (25 February 2022)."Chemistry and human exposure implications of secondary organic aerosol production from indoor terpene ozonolysis".Science Advances.8(8): eabj9156.Bibcode:2022SciA....8J9156R.doi:10.1126/sciadv.abj9156.ISSN2375-2548.PMC8880786.PMID35213219.
  22. ^Zhang, Haofei; Yee, Lindsay D.; Lee, Ben H.; Curtis, Michael P.; Worton, David R.; Isaacman-VanWertz, Gabriel; Offenberg, John H.; Lewandowski, Michael; Kleindienst, Tadeusz E.; Beaver, Melinda R.; Holder, Amara L.; Lonneman, William A.; Docherty, Kenneth S.; Jaoui, Mohammed; Pye, Havala O. T.; Hu, Weiwei; Day, Douglas A.; Campuzano-Jost, Pedro; Jimenez, Jose L.; Guo, Hongyu; Weber, Rodney J.; de Gouw, Joost; Koss, Abigail R.; Edgerton, Eric S.; Brune, William; Mohr, Claudia; Lopez-Hilfiker, Felipe D.; Lutz, Anna; Kreisberg, Nathan M.; Spielman, Steve R.; Hering, Susanne V.; Wilson, Kevin R.; Thornton, Joel A.; Goldstein, Allen H. (12 February 2018)."Monoterpenes are the largest source of summertime organic aerosol in the southeastern United States".Proceedings of the National Academy of Sciences.115(9): 2038–2043.Bibcode:2018PNAS..115.2038Z.doi:10.1073/pnas.1717513115.ISSN0027-8424.PMC5834703.PMID29440409.
  23. ^Wojtunik‐Kulesza, Karolina A.; Kasprzak, Kamila; Oniszczuk, Tomasz; Oniszczuk, Anna (8 November 2019). "Natural Monoterpenes: Much More than Only a Scent".Chemistry & Biodiversity.16(12): e1900434.doi:10.1002/cbdv.201900434.ISSN1612-1872.PMID31587473.S2CID203850556.
  24. ^Kim, Young Woo; Kim, Min Ji; Chung, Bu Young; Bang, Du Yeon; Lim, Seong Kwang; Choi, Seul Min; Lim, Duck Soo; Cho, Myung Chan; Yoon, Kyungsil; Kim, Hyung Sik; Kim, Kyu Bong; Kim, You Sun; Kwack, Seung Jun; Lee, Byung-Mu (1 January 2013). "Safety Evaluation And Risk Assessment Of d-Limonene".Journal of Toxicology and Environmental Health, Part B.16(1): 17–38.doi:10.1080/10937404.2013.769418.ISSN1093-7404.PMID23573938.S2CID40274650.
  25. ^Zárybnický, Tomáš; Boušová, Iva; Ambrož, Martin; Skálová, Lenka (1 January 2018). "Hepatotoxicity of monoterpenes and sesquiterpenes".Archives of Toxicology.92(1): 1–13.doi:10.1007/s00204-017-2062-2.ISSN1432-0738.PMID28905185.S2CID22483285.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Monoterpene&oldid=1226345063"