Omega hydroxy acids (ω-hydroxy acids) are a class of naturally occurring straight-chain

aliphatic In organic chemistry, hydrocarbons ( compounds composed solely of carbon and hydrogen) are divided into two classes: aromatic compounds and aliphatic compounds (; G. ''aleiphar'', fat, oil). Aliphatic compounds can be saturated (in which all ...

organic acids ''n'' carbon atoms long with a

carboxyl In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is often written as or , sometimes as with R referring to an organyl group (e.g. ...

group at position 1 (the starting point for the family of

carboxylic acid In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an Substituent, R-group. The general formula of a carboxylic acid is often written as or , sometimes as with R referring to an organyl ...

s), and a

hydroxyl In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy ...

at terminal position ''n'' where ''n'' > 3. They are a subclass of hydroxycarboxylic acids. The C16 and C18 omega hydroxy acids 16-hydroxy palmitic acid and 18-hydroxy stearic acid are key monomers of

cutin Cutin is one of two waxy polymers that are the main components of the plant cuticle, which covers all aerial surfaces of plants, the other being cutan. It is an insoluble substance with waterproof quality. Cutin also harbors cuticular waxes, ...

in the

plant cuticle A plant cuticle is a protecting film covering the outermost skin layer (epidermis) of leaves, young shoots and other aerial plant organs (aerial here meaning all plant parts not embedded in soil or other substrate) that have no '' periderm''. The ...

. The

polymer A polymer () is a chemical substance, substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeat unit, repeating subunits derived from one or more species of monomers. Due to their br ...

cutin is formed by inter

esterification In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...

of omega hydroxy acids and derivatives of them that are substituted in mid-chain, such as 10,16-dihydroxy palmitic acid.T.J. Walton TJ and P.E. Kolattukudy (1972) Enzymatic conversion of 16-hydroxypalmitic acid into 10,16-dihydroxypalmitic acid in ''Vicia faba'' epidermal extracts. Biochem Biophys Res Communications 46, (1), 16–21P. J. Holloway (1982) The chemical constitution of plant cutins. p45-85 in In "The Plant Cuticle". ed. by DF Cutler, KL Alvin and CE Price. Academic Press, London. Only the epidermal cells of plants synthesize cutin.Kolattukudy, PE (1996) Biosynthetic pathways of cutin and waxes, and their sensitivity to environmental stresses. In: Plant Cuticles. Ed. by G. Kerstiens, BIOS Scientific publishers, Oxford, pp 83-108 Omega hydroxy fatty acids also occur in animals.

Cytochrome P450 Cytochromes P450 (P450s or CYPs) are a Protein superfamily, superfamily of enzymes containing heme as a cofactor (biochemistry), cofactor that mostly, but not exclusively, function as monooxygenases. However, they are not omnipresent; for examp ...

(CYP450)

microsome In cell biology, microsomes are heterogeneous vesicle-like artifacts (~20-200 nm diameter) re-formed from pieces of the endoplasmic reticulum (ER) when eukaryotic cells are broken-up in the laboratory; microsomes are not present in healthy, l ...

ω-hydroxylases such as CYP4A11, CYP4A22, CYP4F2, and CYP4F3 in humans, Cyp4a10 and Cyp4a12 in mice, and Cyp4a1, Cyp4a2, Cyp4a3, and Cyp4a8 in rats metabolize

arachidonic acid Arachidonic acid (AA, sometimes ARA) is a polyunsaturated omega−6 fatty acid 20:4(ω−6), or 20:4(5,8,11,14). It is a precursor in the formation of leukotrienes, prostaglandins, and thromboxanes. Together with omega−3 fatty acids an ...

and many arachidonic acid metabolites to their corresponding omega hydroxyl products. This metabolism of arachidonic acid produces 20-hydroxyarachidonic acid (i.e. 20-hydroxyeicosatetraeonic acid or 20-HETE), a bioactive product involved in various physiological and pathological processes; and this metabolism of certain bioactive arachidonic acid metabolites such as

leukotriene B4 Leukotriene B4 (LTB4) is a leukotriene involved in inflammation. It has been shown to promote insulin resistance in obese mice. Biochemistry LTB4 is a leukotriene involved in inflammation. It is produced from leukocytes in response to inflammato ...

and 5-hydroxyicosatetraenoic acid produces 20-hydroxylated products which are 100- to 1,000-fold weaker than, and therefore represents the inactivation of, their respective precursors.

List

The definition for "omega" includes number of carbons (C#) greater or equal to three. Lower numbers are included here to match the formula pattern C_''n''H_2''n''O₃.

References

{{reflist Hydroxy acids Plant physiology ar:حمض هيدروكسي

List

See also

References