Linoleic acid (LA) is an organic compound with the formula HOOC(CH2)7CH=CHCH2CH=CH(CH2)4CH3. Both alkene groups (−CH=CH−) are cis. It is a fatty acid sometimes denoted 18:2 (n-6) or 18:2 cis-9,12. A linoleate is a salt or ester of this acid.[5]
The word "linoleic" derives from Latin linum 'flax', and oleum 'oil', reflecting the fact that it was first isolated from linseed oil.
Historyedit
In 1844, F. Sacc, working at the laboratory of Justus von Liebig, isolated linoleic acid from linseed oil.[8][9] In 1886, K. Peters determined the existence of two double bonds.[10] Its essential role in human diet was discovered by G. O. Burr and others in 1930.[11] Its chemical structure was determined by T.P. Hilditch and others in 1939, and it was synthesized by R. A. Raphael and F. Sondheimer in 1950.[12]
In physiologyedit
The consumption of linoleic acid is vital to proper health, as it is an essential fatty acid.[13]
Hydroperoxides derived from the metabolism of anandamide (AEA: C 22H 37NO 2; 20:4,n-6), or its linoleoyl analogues, are by a lipoxygenase action found to be competitive inhibitors of brain and immune cellFAAH, the enzyme that breaks down AEA and other endocannabinoids, and the compound linoleoyl-ethanol-amide (C 20H 37NO 2; 18:2,n-6), an N-acylethanolamine,[clarification needed] - the ethanolamide of linoleic acid (LA: C 18H 32O 2; 18:2, n-6) and its metabolized incorporated ethanolamine (MEA: C 2H 7NO),[20] is the first natural inhibitor of FAAH, discovered.[21][22]
Uses and reactionsedit
Linoleic acid is a component of quick-drying oils, which are useful in oil paints and varnishes. These applications exploit the lability of the doubly allylicC−H groups (−CH=CH−CH2−CH=CH−) toward oxygen in air (autoxidation). Addition of oxygen leads to crosslinking and formation of a stable film.[23]
Reduction of the carboxylic acid group of linoleic acid yields linoleyl alcohol.[24]
Linoleic acid is a surfactant with a critical micelle concentration of 1.5 x 10−4 M @ pH 7.5.[citation needed]
Linoleic acid has become increasingly popular in the beauty products industry because of its beneficial properties on the skin. Research points to linoleic acid's anti-inflammatory, acne reductive, skin-lightening and moisture retentive properties when applied topically on the skin.[25][26][27][28]
Linoleic acid is also used in some bar of soap products.
Cockroaches release oleic and linoleic acid upon death, which discourages other roaches from entering the area. This is similar to the mechanism found in ants and bees, which release oleic acid upon death.[44]
Health effectsedit
Consumption of linoleic acid has been associated with lowering the risk of cardiovascular disease, diabetes and premature death.[45][46][47] There is high-quality evidence that increased intake of linoleic acid decreases total blood cholesterol and low-density lipoprotein.[48]
^National Center for Biotechnology Information (2024). PubChem Compound Summary for CID 5280450, Linoleic Acid. Retrieved January 20, 2024 from https://pubchem.ncbi.nlm.nih.gov/compound/Linoleic-Acid.
^"Fatty Acids". Cyber Lipid. Archived from the original on 28 October 2018. Retrieved 31 July 2017.
^Mattes, Richard D. (2009). "Is there a fatty acid taste?". Annual Review of Nutrition. 29: 305–327. doi:10.1146/annurev-nutr-080508-141108. PMC2843518. PMID 19400700.
^Simopoulos, Artemis P. (2008). "The importance of the omega-6/omega-3 fatty acid ratio in cardiovascular disease and other chronic diseases". Experimental Biology and Medicine. 233 (6): 674–688. doi:10.3181/0711-mr-311. PMID 18408140. S2CID 9044197.
^F. Sacc (1844) "Ueber das Leinöl, seine physicalischen und chemischen Eigenscharften und seine Oxydationsproducte". Liebig Annalen, volume 51, pages 213-230.
^F. Sacc (1845): "Expériences sur les propriétés physiques et chimiques de l'huile de Lin". SChweizer. Gesell. N. Dekschr., volume 7
^R. A. Raphael and Franz Sondheimer (1950): "The synthesis of long-chain aliphatic acids from acetylenic compounds. Part III. The synthesis of linoleic acid". Journal of the Chemical Society (Resumed), article 432, doi:10.1039/jr9500002100
^ abWhelan, Jay; Fritsche, Kevin (May 2013). "Linoleic Acid". Advances in Nutrition. 4 (3): 311–312. doi:10.3945/an.113.003772. PMC3650500. PMID 23674797.
^Wlodawer, Paulina; Samuelsson, Bengt (25 August 1973). "On the organization and mechanism of prostaglandin synthetase". The Journal of Biological Chemistry. 248 (16): 5673–5678. doi:10.1016/S0021-9258(19)43558-8. PMID 4723909.
^Terano, Takashi; Salmon, John A.; Moncada, Salvador (February 1984). "Biosynthesis and biological activity of leukotriene B5". Prostaglandins. 27 (2): 217–232. doi:10.1016/0090-6980(84)90075-3. PMID 6326200.
^Murru, Elisabetta; Lopes, Paula A.; Carta, Gianfranca; Manca, Claudia; Abolghasemi, Armita; Guil-Guerrero, José L.; Prates, José A. M.; Banni, Sebastiano (15 February 2021). "Different Dietary N-3 Polyunsaturated Fatty Acid Formulations Distinctively Modify Tissue Fatty Acid and N-Acylethanolamine Profiles". Nutrients. 13 (2): 625. doi:10.3390/nu13020625. ISSN 2072-6643. PMC7919039. PMID 33671938.
^Salem, Norman; Van Dael, Peter (27 February 2020). "Arachidonic Acid in Human Milk". Nutrients. 12 (3): 626. doi:10.3390/nu12030626. ISSN 2072-6643. PMC7146261. PMID 32121018.
^Evidence suggests that infants must acquire Δ6-desaturase breast milk. Breast-milk fed babies have higher concentrations of GLA than formula-fed babies, while formula-fed babies have elevated concentrations of LA. David F. Horrobin (1993). "Fatty acid metabolism in health and disease: the role of Δ-6-desaturase". American Journal of Clinical Nutrition. 57 (5 Suppl): 732S–737S. doi:10.1093/ajcn/57.5.732S. PMID 8386433.
^Jandacek, Ronald J. (20 May 2017). "Linoleic Acid: A Nutritional Quandary". Healthcare. 5 (2): 25. doi:10.3390/healthcare5020025. ISSN 2227-9032. PMC5492028. PMID 28531128.
^PubChem. "Linoleoyl ethanolamide". pubchem.ncbi.nlm.nih.gov. Retrieved 29 October 2022.
^Maccarrone, Mauro; Stelt, Marcelis van der; Rossi, Antonello; Veldink, Gerrit A.; Vliegenthart, Johannes F. G.; Agrò, Alessandro Finazzi (27 November 1998). "Anandamide Hydrolysis by Human Cells in Culture and Brain *". Journal of Biological Chemistry. 273 (48): 32332–32339. doi:10.1074/jbc.273.48.32332. hdl:1887/50863. ISSN 0021-9258. PMID 9822713.
^Scala, Coralie Di; Fantini, Jacques; Yahi, Nouara; Barrantes, Francisco J.; Chahinian, Henri (22 May 2018). "Anandamide Revisited: How Cholesterol and Ceramides Control Receptor-Dependent and Receptor-Independent Signal Transmission Pathways of a Lipid Neurotransmitter". Biomolecules. 8 (2): 31. doi:10.3390/biom8020031. ISSN 2218-273X. PMC6022874. PMID 29789479.
^Diezel, W.E.; Schulz, E.; Skanks, M.; Heise, H. (1993). "Plant oils: Topical application and anti-inflammatory effects (croton oil test)". Dermatologische Monatsschrift. 179: 173.
^Letawe, C.; Boone, M.; Pierard, G.E. (March 1998). "Digital image analysis of the effect of topically applied linoleic acid on acne microcomedones". Clinical and Experimental Dermatology. 23 (2): 56–58. doi:10.1046/j.1365-2230.1998.00315.x. PMID 9692305. S2CID 28594076.
^Ando, Hideya; Ryu, Atsuko; Hashimoto, Akira; Oka, Masahiro; Ichihashi, Masamitsu (March 1998). "Linoleic acid and α-linolenic acid lightens ultraviolet-induced hyperpigmentation of the skin". Archives of Dermatological Research. 290 (7): 375–381. doi:10.1007/s004030050320. PMID 9749992. S2CID 23036319.
^Darmstadt, Gary L.; Mao-Qiang, M.; Chi, E.; Saha, S.K.; Ziboh, V.A.; Black, R.E.; Santosham, M.; Elias, P.M. (2002). "Impact of topical oils on the skin barrier: possible implications for neonatal health in developing countries". Acta Paediatrica. 91 (5): 546–554. CiteSeerX10.1.1.475.1064. doi:10.1080/080352502753711678. PMID 12113324.
^"Nutrient Data Laboratory Home Page". USDA National Nutrient Database for Standard Reference, Release 20. U.S. Department of Agriculture, Agricultural Research Service. 2007. Archived from the original on 14 April 2016.
^Kaur, Narinder; Chugh, Vishal; Gupta, Anil K. (October 2014). "Essential fatty acids as functional components of foods- a review". Journal of Food Science and Technology. 51 (10): 2289–2303. doi:10.1007/s13197-012-0677-0. PMC4190204. PMID 25328170.
^Hall III, C. (2015). Wrigley, Colin W.; Corke, Harold; Seetharaman, Koushik; Faubion, Jonathan (eds.). Encyclopedia of Food Grains. Academic Press. ISBN 978-0-12-394786-4.
^"Evening Primrose Oil for Menopause does it help". 26 January 2018.
^Oomah, B. Dave; Busson, Muriel; Godfrey, David V; Drover, John C. G (1 January 2002). "Characteristics of hemp (Cannabis sativa L.) seed oil". Food Chemistry. 76 (1): 33–43. doi:10.1016/S0308-8146(01)00245-X.
^Nawirska-Olszańska A, Kita A, Biesiada A, Sokół-Łętowska A, Kucharska AZ. (2013). "Characteristics of antioxidant activity and composition of pumpkin seed oils in 12 cultivars". Food Chemistry. 139 (1–4): 155–161. doi:10.1016/j.foodchem.2013.02.009. PMID 23561092.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^Wu, Hao; Shi, John; Xue, Sophia; Kakuda, Yukio; Wang, Dongfeng; Jiang, Yueming; Ye, Xingqian; Li, Yanjun; Subramanian, Jayasankar (2011). "Essential oil extracted from peach (Prunus persica) kernel and its physicochemical and antioxidant properties". LWT - Food Science and Technology. 44 (10): 2032–2039. doi:10.1016/j.lwt.2011.05.012.
^M. K. Nutter, E. E. Lockhart and R. S. Harris (1943). "The chemical composition of depot fats in chickens and turkeys". Journal of the American Oil Chemists' Society. 20 (11): 231–234. doi:10.1007/BF02630880. S2CID 84893770.
^"Earth News: Ancient 'smell of death' revealed". BBC. 9 September 2009.
^Li, Jun; Guasch-Ferré, Marta; Li, Yanping; Hu, Frank B. (2020). "Dietary intake and biomarkers of linoleic acid and mortality: systematic review and meta-analysis of prospective cohort studies". The American Journal of Clinical Nutrition. 112 (1): 150–167. doi:10.1093/ajcn/nqz349. PMC7326588. PMID 32020162.
^Marangoni, Franca; Agostoni, Carlo; Borghi, Claudio; Catapano, Alberico L.; Cena, Hellas; Ghiselli, Andrea; La Vecchia, Carlo; Lercker, Giovanni; Manzato, Enzo; Pirillo, Angela; Riccardi, Gabriele; Risé, Patrizia; Visioli, Francesco; Poli, Andrea (2020). "Dietary linoleic acid and human health: Focus on cardiovascular and cardiometabolic effects". Atherosclerosis. 292: 90–98. doi:10.1016/j.atherosclerosis.2019.11.018. PMID 31785494. S2CID 208516015.
^Mousavi, Seyed Mohammad; Jalilpiran, Yahya; Karimi, Elmira; Aune, Dagfinn; Larijani, Bagher; Mozaffarian, Dariush; Willett, Walter C.; Esmaillzadeh, Ahmad (2021). "Dietary Intake of Linoleic Acid, Its Concentrations, and the Risk of Type 2 Diabetes: A Systematic Review and Dose-Response Meta-analysis of Prospective Cohort Studies". Diabetes Care. 44 (9): 2173–2181. doi:10.2337/dc21-0438. PMID 34417277. S2CID 237255109.
^"Systematic review of the evidence for relationships between saturated, cis monounsaturated, cis polyunsaturated fatty acids and selected individual fatty acids, and blood cholesterol concentration". foodstandards.gov.au. Retrieved 10 January 2023.
^Sacks FM, Lichtenstein AH, Wu JH, Appel LJ, Creager MA, Kris-Etherton PM, Miller M, Rimm EB, Rudel LL, Robinson JG, Stone NJ, Van Horn LV (July 2017). "Dietary Fats and Cardiovascular Disease: A Presidential Advisory From the American Heart Association". Circulation. 136 (3): e1–e23. doi:10.1161/CIR.0000000000000510. PMID 28620111. S2CID 367602.
Further readingedit
"Compound Summary: Linoleic acid". PubChem. U.S. National Library of Medicine.