Linoleic acid (LA) is anorganic compound with the formulaCH3(CH2)4CH=CHCH2CH=CH(CH2)7COOH. Bothalkene groups (−CH=CH−) arecis. It is afatty acid sometimes denoted 18:2 (n−6) or 18:2cis-9,12. Alinoleate is asalt orester of this acid.[5]
In 1844,F. Sacc, working at the laboratory ofJustus 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 byG. O. Burr and others in 1930.[11] Its chemical structure was determined byT. P. Hilditch and others in 1939, and it was synthesized byR. A. Raphael andF. Sondheimer in 1950.[12]
Linoleic acid is a component of quick-drying oils, which are useful inoil paints andvarnishes. These applications exploit the lability of the doublyallylicC−H groups (−CH=CH−CH2−CH=CH−) toward oxygen in air (autoxidation). Addition of oxygen leads tocrosslinking and formation of a stable film.[23]
Reduction of the carboxylic acid group of linoleic acid yieldslinoleyl alcohol.[24]
Linoleic acid is asurfactant 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 theskin.[25][26][27][28]
Linoleic acid is also used in somebar 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.[59]
While polyunsaturated fatty acids are unusual in plant cuticles, a diunsaturated dicarboxylic acid has been reported as a component of the surface waxes or polyesters of some plant species. Thus, octadeca-c6,c9-diene-1,18-dioate, a derivative of linoleic acid, is present inArabidopsis andBrassica napus cuticle.[60]Taxoleic acid is isomeric to linoleic acid.
Consumption of linoleic acid has been associated with lowering the risk ofcardiovascular disease, diabetes and premature death.[61][62][63] There is high-quality evidence that increased intake of linoleic acid decreases total blood cholesterol andlow-density lipoprotein.[64] Higher in vivo circulating and tissue levels of linoleic acid are associated with a lower risk of major cardiovascular events.[65] Clinical trials have shown that increased linoleic acid intake does not increase markers of inflammation or oxidative stress.[66][67]
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^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.PMID9692305.S2CID28594076.
^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.PMID9749992.S2CID23036319.
^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.PMID12113324.
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^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.PMID23561092.
^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.
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^Nutter MK, Lockhart EE, Harris RS (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.S2CID84893770.
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