Omega hydroxy acid explained

Omega hydroxy acids (ω-hydroxy acids) are a class of naturally occurring straight-chain aliphatic organic acids n carbon atoms long with a carboxyl group at position 1 (the starting point for the family of carboxylic acids), and a hydroxyl 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 in the plant cuticle.^{[1] [2]} The polymer cutin is formed by interesterification of omega hydroxy acids and derivatives of them that are substituted in mid-chain, such as 10,16-dihydroxy palmitic acid.^{[3] [4]} Only the epidermal cells of plants synthesize cutin.^[5]

Omega hydroxy fatty acids also occur in animals. Cytochrome P450 (CYP450) microsome 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 and many arachidonic acid metabolites to their corresponding omega hydroxyl products.^[6] 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;^[7] and this metabolism of certain bioactive arachidonic acid metabolites such as leukotriene B4 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.^{[8] [9] [10]}

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_nH_2nO₃.

C#	trivial name	systematic name	melting point °C	formula	SMILES	CASNo	PubChem CID	ChemSpiderID	UNII	ChEBI	occurrence
2	Glycolic acid	2-Hydroxyethanoic acid	75	C2H4O3	OCC(=O)O	79-14-1	757	737	0WT12SX38S	17497	plants
3	Hydroacrylic acid^[11]	3-Hydroxypropionic acid	139-140	C3H6O3	OCCC(=O)O	503-66-2	68152	61460
4	gamma-Hydroxybutyric acid	4-Hydroxybutanoic acid	?	C4H8O3	OCCCC(=O)O	591-81-1	10413	9984	30IW36W5B2	30830	human neurotransmitter
5	5-hydroxyvaleric acid	5-Hydroxypentanoic acid		C5H10O3	OCCCCC(=O)O	13392-69-3	25945	24171	H5EVV4LP59	45564	from engineered Corynebacterium glutamicum^[12]
6	6-Hydroxycaproic acid	6-Hydroxyhexanoic acid		C6H12O3	OCCCCCC(=O)O	1191-25-9	14490	13835	3Y3OX37NM8	17869
7	7-Hydroxyheptanoic acid			C7H14O3	OCCCCCCC(=O)O	3710-42-7	138016	121660		79112
8	omega-hydroxycaprylic acid	8-hydroxyoctanoic acid		C8H16O3	OCCCCCCCC(=O)O	764-89-6	69820	63018		79162
9	9-hydroxypelargonic acid	9-hydroxynonanoic acid		C9H18O3	OCCCCCCCCC(=O)O	3788-56-5	138052	121694	HV672SU12G	79121
10	10-hydroxycapric acid	10-hydroxydecanoic acid		C10H20O3	OCCCCCCCCCC(=O)O	1679-53-4	74300	66903	NP03XO416B	17409
11	11-hydroxyundecanoic acid (11-HUDA)			C11H22O3	OCCCCCCCCCCC(=O)O	3669-80-5	77237	69664	SD6J9LX2XK	79126
12	sabinic acid^[13]	12-hydroxydodecanoic acid		C12H24O3	OCCCCCCCCCCCC(=O)O	505-95-3	79034	71366	SUH3LR2K9D	39567
13	13-hydroxytridecanoic acid			C13H26O3	OCCCCCCCCCCCCC(=O)O	7735-38-8	139065	122656		79166
14	ω-hydroxymyristic acid	14-hydroxytetradecanoic acid		C14H28O3	OCCCCCCCCCCCCCC(=O)O	17278-74-9	084276	2341369		77168	engineered Candida tropicalis^[14]
15		15-hydroxypentadecanoic acid		C15H30O3	OCCCCCCCCCCCCCCC(=O)O	4617-33-8	78360	70730	FU65P3692T	79169	Angelica archangelica
16	juniperic acid	16-hydroxyhexadecanoic acid		C16H32O3	OCCCCCCCCCCCCCCCC(=O)O	506-13-8	10466	10034		55328	plant cuticle^[15]
17	17-hydroxyheptadecanoic acid			C17H34O3	OCCCCCCCCCCCCCCCCC(=O)O	13099-34-8	4308451	3513977		79177	Pinus radiata
18	ω-hydroxystearic acid	18-hydroxyoctadecanoic acid		C18H36O3	OCCCCCCCCCCCCCCCCCC(=O)O	3155-42-8	5282915	4446042	CCR5P6ICT2	79182	plant cutin
19	19-hydroxynonadecanoic acid			C19H38O3	OCCCCCCCCCCCCCCCCCCC(=O)O		5282917	4446044		79179
20	ω-hydroxyarachidic acid	20-hydroxyicosanoic acid		C20H40O3	OCCCCCCCCCCCCCCCCCCCC(=O)O	62643-46-3	5282919	4446046		79190	stem and seed cutin
21	21-hydroxyhenicosanoic acid			C21H42O3	OCCCCCCCCCCCCCCCCCCCCC(=O)O		5282920	4446047		79195
22	22-hydroxybehenic acid	22-Hydroxydocosanoic acid		C22H44O3	OCCCCCCCCCCCCCCCCCCCCCC(=O)O	506-45-6	5282922	4446049		76322
23	23-hydroxytricosanoic acid			C23H46O3	OCCCCCCCCCCCCCCCCCCCCCCC(=O)O	61658-18-2	11760442	9935141			cutin
24	24-hydroxytetracosanoic acid			C24H48O3	OCCCCCCCCCCCCCCCCCCCCCCCC(=O)O	75912-18-4	5312780	4472205
25	25-hydroxypentacosanoic acid			C25H50O3	OCCCCCCCCCCCCCCCCCCCCCCCCC(=O)O	82612-07-5	14325176	57507583
26	ω-hydroxycerotic acid	26-hydroxyhexacosanoic acid		C26H52O3	OCCCCCCCCCCCCCCCCCCCCCCCCCC(=O)O	506-47-8	5312785	4472210		76325
27	27-hydroxyheptacosanoic acid			C27H54O3	OCCCCCCCCCCCCCCCCCCCCCCCCCCC(=O)O		14325177	13739624		84861
28	28-hydroxyoctacosanoic acid			C28H56O3	OCCCCCCCCCCCCCCCCCCCCCCCCCCCC(=O)O	52900-17-1	5312786	4472211		84863
29	omega-hydroxynonacosanoic acid	29-hydroxynonacosanoic acid		C29H58O3	OCCCCCCCCCCCCCCCCCCCCCCCCCCCCC(=O)O		14325178	34449103		84865
30	30-hydroxytriacontanoic acid			C30H60O3	OCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC(=O)O	52900-18-2	5312787	4472212		76220

See also

• Alpha hydroxy acid
• Beta hydroxy acid

Notes and References

1. Kolattukudy . P. E. . Walton . T. J. . 1972 . Structure and biosynthesis of the hydroxy fatty acids of cutin in Vicia faba leaves . Biochemistry . 11 . 10. 1897–1907 . 10.1021/bi00760a026. 5025632.
2. Soliday . C. L. . Kolattukudy . P. E. . 1977 . Biosynthesis of Cutin ω-hydroxylation of fatty acids by a microsomal preparation from germinating Vicia faba . Plant Physiology . 59 . 6. 1116–1121 . 10.1104/pp.59.6.1116. 542517 . 16660004.
3. 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), 16–21
4. P. 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.
5. 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
6. Hoopes SL, Garcia V, Edin ML, Schwartzman ML, Zeldin DC . Vascular actions of 20-HETE . Prostaglandins & Other Lipid Mediators . 120 . 9–16 . Jul 2015 . 25813407 . 10.1016/j.prostaglandins.2015.03.002 . 4575602.
7. Annu Rev Pharmacol Toxicol. 2005;45:413-38
8. 10.1016/j.abb.2009.01.012 . 484 . 20-Hydroxylation is the CYP-dependent and retinoid-inducible leukotriene B4 inactivation pathway in human and mouse skin cells . Archives of Biochemistry and Biophysics . 80–86 . 19467632 . 2687325 . Du . L . Yin . H . Morrow . JD . Strobel . HW . Keeney . DS . 2009. 1 .
9. J Immunol. 1986 Nov 15;137(10):3277-83
10. 10.1016/j.bbalip.2014.10.008 . 25449650 . 1851 . Biosynthesis, biological effects, and receptors of hydroxyeicosatetraenoic acids (HETEs) and oxoeicosatetraenoic acids (oxo-ETEs) derived from arachidonic acid. . Apr 2015 . Biochim Biophys Acta . 340–355 . Powell . WS . Rokach . J. 4 . 5710736 .
11. Book: 10.1002/14356007.a13_507 . Hydroxycarboxylic Acids, Aliphatic . Ullmann's Encyclopedia of Industrial Chemistry . 2000 . Miltenberger . Karlheinz . 978-3-527-30385-4 .
12. 10.1021/acssuschemeng.0c08118 . Fermentative High-Level Production of 5-Hydroxyvaleric Acid by Metabolically Engineered Corynebacterium glutamicum . 2021 . Sohn . Yu Jung . Kang . Minsoo . Baritugo . Kei-Anne . Son . Jina . Kang . Kyoung Hee . Ryu . Mi-Hee . Lee . Siseon . Sohn . Mingi . Jung . Ye Jean . Park . Kyungmoon . Park . Si Jae . Joo . Jeong Chan . Kim . Hee Taek . ACS Sustainable Chemistry & Engineering . 9 . 6 . 2523–2533 .
13. Lycan . W. H. . Adams . Roger . Omega-Hydroxy Aliphatic Acids. Synthesis of Sabinic Acid . February 1929 . Journal of the American Chemical Society . en . 51 . 2 . 625–629 . 10.1021/ja01377a042 . 0002-7863. subscription .
14. 10.1021/bm2007554 . Polymers from Fatty Acids: Poly(ω-hydroxyl tetradecanoic acid) Synthesis and Physico-Mechanical Studies . 2011 . Liu . Chen . Liu . Fei . Cai . Jiali . Xie . Wenchun . Long . Timothy E. . Turner . S. Richard . Lyons . Alan . Gross . Richard A. . Biomacromolecules . 12 . 9 . 3291–3298 . 21793591 .
15. Spring . F. S. . March 1945 . Naturally Occurring Polyesters . Nature . en . 155 . 3931 . 272 . 10.1038/155272b0 . 1945Natur.155..272S . 4108900 . 0028-0836. free .