Fatty alcohol

Fatty alcohols are aliphatic alcohols derived from natural fats and oils, originating in plants, but also synthesized in animals and algae. Their importance in nutrition and health has been overlooked, and is only now being realized, as they are closely related to fatty acids, including the well documented omega 3 fatty acids. The other counterparts are fatty aldehydes. Fatty alcohols usually have even number of carbon atoms. Production from fatty acids yields normal-chain alcohols&mdash;the alcohol group (-OH) attaches to the terminal carbon. Other processing can yield iso-alcohols&mdash;where the alcohol attaches to a carbon in the interior of the carbon chain.

Current and future uses
The smaller molecules are used in cosmetics and food, and as industrial solvents. Some of the larger molecules are simply seen as biofuels, but little research has been done until 2006 regarding many of these, and they have been shown to be have anticancer, antiviral, antifungal, anti-HIV properties, for potential use in medicine and health supplements.

Due to their amphipathic nature, fatty alcohols behave as nonionic surfactants. They find use as emulsifiers, emollients and thickeners in cosmetics and food industry.

Fatty alcohols are a common component of waxes, mostly as esters with fatty acids but also as alcohols themselves.

History
Search for polyisoprenoid alcohols was initiated with the accidental discovery of solanesol in tobacco leaves (Rowland RL et al., J Am Chem Soc 1956, 78, 4680) and isolation of several polyprenols (C30-C45) in cellulose pulp extracts (Lindgren BO, Acta Chem Scan 1965, 19, 1317).

Octacosanol, present in carrots and ginseng, was found to lower cholesterol levels in 1994. Following this, a major paper was released in 2006 and another in 2007 studying hundreds of previously unstudied fatty alcohols. More than 120 cytotoxic anticancer compounds have shown confirmed activity in vitro tumor cell lines bioassay and are of current interest to Natural Cancer Institute (of Poland) for further in vivo evaluation.

Types

 * Normal-chain alcohols
 * Saturated alcohols
 * Unsaturated alcohols
 * Acetylenic alcohols
 * Sulfated alcohols
 * Branched-chain alcohols
 * Mono-methylated alcohols
 * Polyisoprenoid alcohols
 * Saturated polyisoprenoids (Isopranols)
 * Unsaturated polyisoprenoids (prenols or polyprenols) incl turpenols.
 * Phenolic alcohols (aka phenolphthiocerol)

Common names
Those with common names include:
 * capryl alcohol (1-octanol) -- 8 carbon atoms
 * 2-ethyl hexanol -- 8 carbon atoms, branched
 * pelargonic alcohol (1-nonanol) -- 9 carbon atoms
 * capric alcohol (1-decanol, decyl alcohol) -- 10 carbon atoms
 * 1-dodecanol (lauryl alcohol) -- 12 carbon atoms
 * myristyl alcohol (1-tetradecanol) -- 14 carbon atoms
 * cetyl alcohol (1-hexadecanol) -- 16 carbon atoms
 * palmitoleyl alcohol (cis-9-hexadecan-1-ol) -- 16 carbon atoms, unsaturated, CH3(CH2)5CH=CH(CH2)8OH
 * stearyl alcohol (1-octadecanol) -- 18 carbon atoms
 * isostearyl alcohol (16-methylheptadecan-1-ol) -- 18 carbon atoms, branched, (CH3)2CH-(CH2)15OH
 * elaidyl alcohol (9E-octadecen-1-ol) -- 18 carbon atoms, unsaturated, CH3(CH2)7CH=CH(CH2)8OH
 * oleyl alcohol (cis-9-octadecen-1-ol) -- 18 carbon atoms, unsaturated
 * linoleyl alcohol (9Z, 12Z-octadecadien-1-ol) -- 18 carbon atoms, polyunsaturated, a hydrolyzation of linolinic acid, an omega 6 fatty acid.
 * elaidolinoleyl alcohol (9E, 12E-octadecadien-1-ol) -- 18 carbon atoms, polyunsaturated
 * linolenyl alcohol (9Z, 12Z, 15Z-octadecatrien-1-ol) -- 18 carbon atoms, polyunsaturated
 * elaidolinolenyl alcohol (9E, 12E, 15-E-octadecatrien-1-ol) -- 18 carbon atoms, polyunsaturated
 * ricinoleyl alcohol (12-hydroxy-9-octadecen-1-ol) -- 18 carbon atoms, unsaturated, diol, CH3(CH2)5CH(OH)CH2CH=CH(CH2)8OH
 * arachidyl alcohol (1-eicosanol) -- 20 carbon atoms
 * behenyl alcohol (1-docosanol) -- 22 carbon atoms
 * erucyl alcohol (cis-13-docosen-1-ol) -- 22 carbon atoms, unsaturated, CH3(CH2)7CH=CH(CH2)12OH
 * lignoceryl alcohol (1-tetracosanol) -- 24 carbon atoms
 * ceryl alcohol (1-hexacosanol) -- 26 carbon atoms
 * montanyl alcohol, cluytyl alcohol (1-octacosanol) -- 28 carbon atoms
 * myricyl alcohol, melissyl alcohol (1-triacontanol) -- 30 carbon atoms
 * geddyl alcohol (1-tetratriacontanol) -- 34 carbon atoms

Behenyl alcohol, lignoceryl alcohol, ceryl alcohol, 1-heptacosanol, montanyl alcohol, 1-nonacosanol, myricyl alcohol, 1-dotriacontanol, and geddyl alcohol are together classified as policosanol, with montanyl alcohol and myricyl alcohol being the most abundant.

Nutrition
Very long chain fatty alcohols (VLCFA), obtained from plant waxes and beeswax have been reported to lower plasma cholesterol in humans. They can be found in unrefined cereal grains, beeswax, and many plant-derived foods. Reports suggest that 5–20 mg per day of mixed C24–C34 alcohols, including octacosanol and triacontanol, lower low-density lipoprotein (LDL) cholesterol by 21%–29% and raise high-density lipoprotein cholesterol by 8%–15%. Wax esters are hydrolyzed by a bile salt–dependent pancreatic carboxyl esterase, releasing long chain alcohols and fatty acids that are absorbed in the gastrointestinal tract. Studies of fatty alcohol metabolism in fibroblasts suggest that very long chain fatty alcohols, fatty aldehydes, and fatty acids are reversibly inter-converted in a fatty alcohol cycle. The metabolism of these compounds is impaired in several inherited human peroxisomal disorders, including adrenoleukodystrophy and Sjögren-Larsson syndrome. Concentrations of VLCFA in blood plasma increase during fasting and when children are placed on ketogenic diets to suppress seizures.

Article Sources

 * General overview of fatty alchols, with references.