Palmitic acid
| Palmitic acid[1] | |
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hexadecanoic acid |
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Other names
C16:0 (Lipid numbers), palmic acid |
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| Identifiers | |
| CAS number | 57-10-3  |
| PubChem | 985 |
| ChEMBL | CHEMBL82293  |
| IUPHAR ligand | 1055 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | C16H32O2 |
| Molar mass | 256.42 g/mol |
| Appearance | White crystals |
| Density | 0.853 g/cm3 at 62 °C |
| Melting point |
62.9 °C[2] |
| Boiling point |
351-352 °C[3] |
| Solubility in water | Insoluble |
 (verify) (what is:  / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Palmitic acid, or hexadecanoic acid in IUPAC nomenclature, is one of the most common fatty acids found in animals and plants. It is a major component of the oil from palm trees (palm oil, palm kernel oil and coconut oil). However, palmitic acid can also be found in meats, cheeses, butter, and dairy products.
Its molecular formula is CH3(CH2)14CO2H. As its name indicates, it is a major component of the oil from palm trees (palm oil, palm kernel oil, and coconut oil). Palmitate is a term for the salts and esters of palmitic acid. The palmitate anion is the observed form of palmitic acid at basic pH.
Palmitic acid has been shown to kill the beta cells in the pancreas that are responsible for the secretion of insulin, and to suppress the body's natural appetite-suppressing signals from leptin and insulin -- the key hormones involved in weight regulation[4].
Aluminum salts of palmitic acid and naphthenic acid were combined during World War II to produce napalm (aluminum naphthenate and aluminum palmitate). The word "napalm" is derived from the words naphthenic acid and palmitic acid.
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[edit] Occurrence and production
Palmitic acid mainly occurs as its ester in triglycerides (fats), especially palm oil but also tallow. The cetyl ester of palmitic acid (cetyl palmitate) occurs in spermiceti. It was discovered by Edmond Frémy in 1840, in saponified palm oil.[5] Butter, cheese, milk and meat also contain this fatty acid.
Palmitic acid is prepared by treating fats and oils with water at a high pressure and temperature (above 200 °C), leading to the hydrolysis of triglycerides. The resulting mixture is then distilled.[6]
[edit] Biochemistry
Excess carbohydrates in the body are converted to palmitic acid. Palmitic acid is the first fatty acid produced during fatty acid synthesis and the precursor to longer fatty acids. Palmitate negatively feeds back on acetyl-CoA carboxylase (ACC), which is responsible for converting acetyl-CoA to malonyl-CoA, which in turn is used to add to the growing acyl chain, thus preventing further palmitate generation.[7] In biology, some proteins are modified by the addition of a palmitoyl group in a process known as palmitoylation. Palmitoylation is important for membrane localisation of many proteins.
[edit] Applications
Palmitic acid is mainly used to produce soaps, cosmetics, and release agents. These applications utilize sodium palmitate, which is commonly obtained by saponification of palm oil. To this end, palm oil, rendered from the coconut palm nut, is treated with sodium hydroxide (in the form of caustic soda or lye), which causes hydrolysis of the ester groups. This procedure affords glycerol and sodium palmitate.
Because it is inexpensive and adds texture to processed foods (convenience food), palmitic acid and its sodium salt find wide use including foodstuffs. Sodium palmitate is permitted as a natural additive in organic products.[8]
Hydrogenation of palmitic acid yields cetyl alcohol, which is used to produce detergents and cosmetics.
Recently, a long-acting antipsychotic medication, paliperidone palmitate (marketed as INVEGA Sustenna), used in the treatment of schizophrenia, has been synthesized using the oily palmitate ester as a long-acting release carrier medium when injected intramuscularly. The underlying method of drug delivery is similar to that used with decanoic acid to deliver long-acting depot medication, in particular, neuroleptics such as haloperidol decanoate.
[edit] Dietary effect
According to the World Health Organization, evidence is "convincing" that consumption of palmitic acid increases risk of developing cardiovascular diseases, placing it in the same evidence category as trans fatty acids.[9] Retinyl palmitate is an antioxidant and a source of vitamin A added to low fat milk to replace the vitamin content lost through the removal of milk fat. Palmitate is attached to the alcohol form of vitamin A, retinol, to make vitamin A stable in milk.
[edit] See also
[edit] References
- ^ Merck Index, 12th Edition, 7128.
- ^ Beare-Rogers, J.; Dieffenbacher, A.; Holm, J.V. (2001). "Lexicon of lipid nutrition (IUPAC Technical Report)". Pure and Applied Chemistry 73 (4): 685–744. doi:10.1351/pac200173040685. http://iupac.org/publications/pac/73/4/0685/.
- ^ Palmitic acid at Inchem.org
- ^ Palmitic acid mediates hypothalamic insulin resistance by altering PKC-θ subcellular localization in rodents, Journal of Clinical Investigation
- ^ E. Frémy, Memoire sur les produits de la saponification de l’huile de palme, Journal de Pharmacie et de Chimie XII (1842), p. 757.
- ^ David J. Anneken, Sabine Both, Ralf Christoph, Georg Fieg, Udo Steinberner, Alfred Westfechtel "Fatty Acids" in Ullmann's Encyclopedia of Industrial Chemistry 2006, Wiley-VCH, Weinheim. doi:10.1002/14356007.a10_245.pub2
- ^ Fatty acid biosynthesis - Reference pathway
- ^ US Soil Association standard 50.5.3
- ^ DIET, NUTRITION AND THE PREVENTION OF CHRONIC DISEASES, WHO Technical Report Series 916, Report of a Joint WHO/FAO Expert Consultation, World Health Organization, Geneva, 2003, p. 88 (Table 10)
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