# Omega hydroxy acid

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. 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. Only the epidermal cells of plants synthesize cutin.
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. 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 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$_{2n}$O$_3$.
| C# | trivial name | systematic name | melting point °C | formula | SMILES | CASNo | PubChem CID | ChemSpiderID | UNII | ChEBI | occurrence |
| 2 | Glycolic acid | 2-Hydroxyethanoic acid | 75 | C$_2$H$_4$O$_3$ | OCC(=O)O | 79-14-1 | 757 | 737 | 0WT12SX38S | 17497 | plants |
| 3 | Hydroacrylic acid | 3-Hydroxypropionic acid | 139-140 | C$_3$H$_6$O$_3$ | OCCC(=O)O | 503-66-2 | 68152 | 61460 | | | |
| 4 | gamma-Hydroxybutyric acid | 4-Hydroxybutanoic acid | ? | C$_4$H$_8$O$_3$ | OCCCC(=O)O | 591-81-1 | 10413 | 9984 | 30IW36W5B2 | 30830 | human neurotransmitter |
| 5 | 5-hydroxyvaleric acid | 5-Hydroxypentanoic acid | | C$_5$H$_{10}$O$_3$ | OCCCCC(=O)O | 13392-69-3 | 25945 | 24171 | H5EVV4LP59 | 45564 | from engineered Corynebacterium glutamicum |
| 6 | 6-Hydroxycaproic acid | 6-Hydroxyhexanoic acid | | C$_6$H$_{12}$O$_3$ | OCCCCCC(=O)O | 1191-25-9 | 14490 | 13835 | 3Y3OX37NM8 | 17869 | |
| 7 | 7-Hydroxyheptanoic acid | | | C$_7$H$_{14}$O$_3$ | OCCCCCCC(=O)O | 3710-42-7 | 138016 | 121660 | | 79112 | |
| 8 | omega-hydroxycaprylic acid | 8-hydroxyoctanoic acid | | C$_8$H$_{16}$O$_3$ | OCCCCCCCC(=O)O | 764-89-6 | 69820 | 63018 | | 79162 | |
| 9 | 9-hydroxypelargonic acid | 9-hydroxynonanoic acid | | C$_9$H$_{18}$O$_3$ | OCCCCCCCCC(=O)O | 3788-56-5 | 138052 | 121694 | HV672SU12G | 79121 | |
| 10 | 10-hydroxycapric acid | 10-hydroxydecanoic acid | | C$_{10}$H$_{20}$O$_3$ | OCCCCCCCCCC(=O)O | 1679-53-4 | 74300 | 66903 | NP03XO416B | 17409 | |
| 11 | 11-hydroxyundecanoic acid (11-HUDA) | | | C$_{11}$H$_{22}$O$_3$ | OCCCCCCCCCCC(=O)O | 3669-80-5 | 77237 | 69664 | SD6J9LX2XK | 79126 | |
| 12 | sabinic acid | 12-hydroxydodecanoic acid | | C$_{12}$H$_{24}$O$_3$ | OCCCCCCCCCCCC(=O)O | 505-95-3 | 79034 | 71366 | SUH3LR2K9D | 39567 | |
| 13 | 13-hydroxytridecanoic acid | | | C$_{13}$H$_{26}$O$_3$ | OCCCCCCCCCCCCC(=O)O | 7735-38-8 | 139065 | 122656 | | 79166 | |
| 14 | ω-hydroxymyristic acid | 14-hydroxytetradecanoic acid | | C$_{14}$H$_{28}$O$_3$ | OCCCCCCCCCCCCCC(=O)O | 17278-74-9 | 084276 | 2341369 | | 77168 | engineered Candida tropicalis |
| 15 | | 15-hydroxypentadecanoic acid | | C$_{15}$H$_{30}$O$_3$ | OCCCCCCCCCCCCCCC(=O)O | 4617-33-8 | 78360 | 70730 | FU65P3692T | 79169 | Angelica archangelica |
| 16 | juniperic acid | 16-hydroxyhexadecanoic acid | | C$_{16}$H$_{32}$O$_3$ | OCCCCCCCCCCCCCCCC(=O)O | 506-13-8 | 10466 | 10034 | | 55328 | plant cuticle |
| 17 | 17-hydroxyheptadecanoic acid | | | C$_{17}$H$_{34}$O$_3$ | OCCCCCCCCCCCCCCCCC(=O)O | 13099-34-8 | 4308451 | 3513977 | | 79177 | Pinus radiata |
| 18 | ω-hydroxystearic acid | 18-hydroxyoctadecanoic acid | | C$_{18}$H$_{36}$O$_3$ | OCCCCCCCCCCCCCCCCCC(=O)O | 3155-42-8 | 5282915 | 4446042 | CCR5P6ICT2 | 79182 | plant cutin |
| 19 | 19-hydroxynonadecanoic acid | | | C$_{19}$H$_{38}$O$_3$ | OCCCCCCCCCCCCCCCCCCC(=O)O | | 5282917 | 4446044 | | 79179 | |
| 20 | ω-hydroxyarachidic acid | 20-hydroxyicosanoic acid | | C$_{20}$H$_{40}$O$_3$ | OCCCCCCCCCCCCCCCCCCCC(=O)O | 62643-46-3 | 5282919 | 4446046 | | 79190 | stem and seed cutin |
| 21 | 21-hydroxyhenicosanoic acid | | | C$_{21}$H$_{42}$O$_3$ | OCCCCCCCCCCCCCCCCCCCCC(=O)O | | 5282920 | 4446047 | | 79195 | |
| 22 | 22-hydroxybehenic acid | 22-Hydroxydocosanoic acid | | C$_{22}$H$_{44}$O$_3$ | OCCCCCCCCCCCCCCCCCCCCCC(=O)O | 506-45-6 | 5282922 | 4446049 | | 76322 | |
| 23 | 23-hydroxytricosanoic acid | | | C$_{23}$H$_{46}$O$_3$ | OCCCCCCCCCCCCCCCCCCCCCCC(=O)O | 61658-18-2 | 11760442 | 9935141 | | | cutin |
| 24 | 24-hydroxytetracosanoic acid | | | C$_{24}$H$_{48}$O$_3$ | OCCCCCCCCCCCCCCCCCCCCCCCC(=O)O | 75912-18-4 | 5312780 | 4472205 | | | |
| 25 | 25-hydroxypentacosanoic acid | | | C$_{25}$H$_{50}$O$_3$ | OCCCCCCCCCCCCCCCCCCCCCCCCC(=O)O | 82612-07-5 | 14325176 | 57507583 | | | |
| 26 | ω-hydroxycerotic acid | 26-hydroxyhexacosanoic acid | | C$_{26}$H$_{52}$O$_3$ | OCCCCCCCCCCCCCCCCCCCCCCCCCC(=O)O | 506-47-8 | 5312785 | 4472210 | | 76325 | |
| 27 | 27-hydroxyheptacosanoic acid | | | C$_{27}$H$_{54}$O$_3$ | OCCCCCCCCCCCCCCCCCCCCCCCCCCC(=O)O | | 14325177 | 13739624 | | 84861 | |
| 28 | 28-hydroxyoctacosanoic acid | | | C$_{28}$H$_{56}$O$_3$ | OCCCCCCCCCCCCCCCCCCCCCCCCCCCC(=O)O | 52900-17-1 | 5312786 | 4472211 | | 84863 | |
| 29 | omega-hydroxynonacosanoic acid | 29-hydroxynonacosanoic acid | | C$_{29}$H$_{58}$O$_3$ | OCCCCCCCCCCCCCCCCCCCCCCCCCCCCC(=O)O | | 14325178 | 34449103 | | 84865 | |
| 30 | 30-hydroxytriacontanoic acid | | | C$_{30}$H$_{60}$O$_3$ | OCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC(=O)O | 52900-18-2 | 5312787 | 4472212 | | 76220 | |