Vernolic acid

Vernolic acid (leukotoxin B^[1] or isoleukotoxin^[2]) is a long chain fatty acid that is monounsaturated and contains an epoxide. It is a cis epoxide derived from the C12–C13 alkene of linoleic acid.^[3] Vernolic acid was first definitively characterized in 1954^[4] and its absolute configuration determined in 1966.^[5] It is a major component in vernonia oil, which is produced in abundance by the genera Vernonia and Euphorbia and is a potentially useful biofeedstock.

Vernolic acid

(−)-(12R,13S)-EpOME
Names
Preferred IUPAC name (9Z)-(12S,13R)-12,13-epoxyoctadecenoic acid
Other names Racemic: Linoleic acid 12,13-oxide cis-12-Epoxyoctadeca-cis-9-enoic acid Single-enantiomer (corresponding to IUPAC-name isomer): (+)-(12S,13R)-epoxy-cis-9-octadecenoic acid 12S,13R-EpOME
Identifiers
CAS Number	503-07-1 (+)-isomer Y 32381-42-3 (−)-isomer Y 17966-13-1 (racemate) Y
3D model (JSmol)	(−)-isomer: Interactive image (+)-isomer: Interactive image
ChEBI	CHEBI:38300 (−)-isomer Y CHEBI:27706 (+)-isomer Y
ChemSpider	4444572 (−)-isomer N 4952464 (+)-isomer N
PubChem CID	5281128 (−)-isomer 6449780 (+)-isomer
UNII	FR42854EPW (+)-isomer Y FF156V3318 (−)-isomer Y 4S5JF40ZOQ (racemate) Y
CompTox Dashboard (EPA)	DTXSID001205124
InChI InChI=1S/C18H32O3/c1-2-3-10-13-16-17(21-16)14-11-8-6-4-5-7-9-12-15-18(19)20/h8,11,16-17H,2-7,9-10,12-15H2,1H3,(H,19,20)/b11-8-/t16-,17+/m0/s1 N Key: CCPPLLJZDQAOHD-BEBBCNLGSA-N N (−)-isomer: InChI=1/C18H32O3/c1-2-3-10-13-16-17(21-16)14-11-8-6-4-5-7-9-12-15-18(19)20/h8,11,16-17H,2-7,9-10,12-15H2,1H3,(H,19,20)/b11-8-/t16-,17+/m0/s1 Key: CCPPLLJZDQAOHD-BEBBCNLGBK (+)-isomer: InChI=1/C18H32O3/c1-2-3-10-13-16-17(21-16)14-11-8-6-4-5-7-9-12-15-18(19)20/h8,11,16-17H,2-7,9-10,12-15H2,1H3,(H,19,20)/b11-8-/t16-,17+/m1/s1 Key: CCPPLLJZDQAOHD-GJGKEFFFBZ (+)-isomer: InChI=1S/C18H32O3/c1-2-3-10-13-16-17(21-16)14-11-8-6-4-5-7-9-12-15-18(19)20/h8,11,16-17H,2-7,9-10,12-15H2,1H3,(H,19,20)/b11-8-/t16-,17+/m1/s1 Key: CCPPLLJZDQAOHD-GJGKEFFFSA-N
SMILES (−)-isomer: O=C(O)CCCCCCC/C=C\C[C@H]1O[C@H]1CCCCC (+)-isomer: O=C(O)CCCCCCC/C=C\C[C@@H]1O[C@@H]1CCCCC
Properties
Chemical formula	C18H32O3
Molar mass	296.451 g·mol−1
Appearance	Colorless oil
Melting point	23 to 25 °C (73 to 77 °F; 296 to 298 K)
Solubility in water	Insoluble
Solubility in other solvents	organic solvents
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	flammable
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Occurrence

Vernonia oil is extracted from the seeds of the Vernonia galamensis (ironweed), a plant native to eastern Africa. The seeds contain about 40 to 42% oil of which 73 to 80% is vernolic acid. The best varieties of V. anthelmintica contain about 30% less vernolic acid.

Vernolic acid is not commonly found in plants in significant quantities, but some plants which do contain it are Vernonia, Stokesia, Crepis (from the daisy family), and Euphorbia lagascae and Bernardia pulchella from the Euphorbiaceae.^[6]

Potential applications

Vernonia oil has been proposed as a precursor to adhesives, varnishes and paints, and industrial coatings. Its low viscosity recommends its use as a nonvolatile solvent in oil-based paints since it will become incorporated in the dry paint rather than evaporating into the air.^[7]

In its application as an epoxy oil,^[8] vernonia oil competes with soybean or linseed oil, which supply most of the market for these applications. Its low viscosity makes it more desirable than fully epoxidized linseed or soybean oils. It is comparable to partially epoxidized linseed or soybean oil.^[9]

Toxicity

In a variety of mammalian species, vernolic acid is made by the metabolism of linoleic acid by cytochrome P450 epoxygenase enzymes; under these circumstances it is termed leukotoxin because of its toxic effects on leukocytes and other cell types and of its ability to produce multiple organ failure and respiratory distress when injected into rodent animal models of the acute respiratory distress syndrome.^[10][11][12] These effects appear due to the conversion of vernolic acid to its dihydroxy counterparts. For instance, (12S,13R)-EpOME is converted by soluble epoxide hydrolase (sEH) to (12R,13R)-dihydroxy-9Z-octadecenoic acid due to inversion at C12 carbon atom during hydrolysis. A mixture of this dihydroxy acid with its 12S,13S enantiomer has been termed isoleukotoxin diol.^{[13][11][14]: Fig. 1} Some studies suggest but have not yet proven that vernolic acid is responsible for or contributes to multiple organ failure, respiratory distress, and certain other cataclysmic diseases in humans (see Epoxygenase § Linoleic acid).

Related compounds

• coronaric acid, C9-C10 epoxide of linoleic acid.

References

1. National Center for Biotechnology Information. "PubChem Compound Summary for CID 6449780, Vernolic acid". PubChem. Retrieved 29 May 2023.
2. Quaranta A, Revol-Cavalier J, Wheelock CE (December 2022). "The octadecanoids: an emerging class of lipid mediators". Biochem Soc Trans. 50 (6): 1569–1582[1575]. doi:10.1042/BST20210644. PMC 9788390. PMID 36454542.
3. Hildreth K, Kodani SD, Hammock BD, Zhao L (December 2020). "Cytochrome P450-derived Linoleic Acid Metabolites EpOMEs and DiHOMEs: A Review of Recent Studies". The Journal of Nutritional Biochemistry. 86 (article 108484). doi:10.1016/j.jnutbio.2020.108484. PMC 7606796. PMID 32827665.
4. Gunstone FD (1954). "Fatty acids. Part II. The nature of the oxygenated acid present in Vernonia anthelmintica (Willd.) seed oil". Journal of the Chemical Society. 1954: 1611–1616. doi:10.1039/JR9540001611.
5. Morris, L.J.; Wharry, D.M. (January 1966). "Naturally occurring epoxy acids. IV. The absolute optical configuration of vernolic acid". Lipids. 1 (1). American Oil Chemists' Society: 41–46. doi:10.1007/BF02668123.
6. Cahoon EB, Ripp KG, Hall SE, McGonigle B (February 2002). "Transgenic production of epoxy fatty acids by expression of a cytochrome P450 enzyme from Euphorbia lagascae seed". Plant Physiology. 128 (2): 615–24. doi:10.1104/pp.010768. PMC 148923. PMID 11842164.
7. Teynor TM, Putnam DJ, Oplinger ES, Oelke EA, Kelling KA, Doll JD (February 1992). "Vernonia". Alternative Field Crops Manual. Retrieved 2006-09-10.
8. Mohamed AI, Mebrahtu T, Andebrhan T (1999). Janick J (ed.). "Variability in oil and vernolic acid contents in the new Vernonia galamensis collection from East Africa". Perspectives on New Crops and New Uses: 272–274. Retrieved 2006-09-10.
9. Muturi P, Wang D, Dirlikov S (1994). "Epoxidized vegetable oils as reactive diluents I. Comparison of vernonia, epoxidized soybean and epoxidized linseed oils". Progress in Organic Coatings. 25: 85–94. doi:10.1016/0300-9440(94)00504-4.
10. Linhartová I, Bumba L, Mašín J, Basler M, Osička R, Kamanová J, Procházková K, Adkins I, Hejnová-Holubová J, Sadílková L, Morová J, Sebo P (November 2010). "RTX proteins: a highly diverse family secreted by a common mechanism". FEMS Microbiology Reviews. 34 (6): 1076–112. doi:10.1111/j.1574-6976.2010.00231.x. PMC 3034196. PMID 20528947.
11. Spector AA, Kim HY (April 2015). "Cytochrome P450 epoxygenase pathway of polyunsaturated fatty acid metabolism". Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids. 1851 (4): 356–65. doi:10.1016/j.bbalip.2014.07.020. PMC 4314516. PMID 25093613.
12. Edwards, L. M.; Lawler, N. G.; Nikolic, S. B.; Peters, J. M.; Horne, J; Wilson, R; Davies, N. W.; Sharman, J. E. (2012). "Metabolomics reveals increased isoleukotoxin diol (12,13-DHOME) in human plasma after acute Intralipid infusion". The Journal of Lipid Research. 53 (9): 1979–86. doi:10.1194/jlr.P027706. PMC 3413237. PMID 22715155.
13. Greene JF, Newman JW, Williamson KC, Hammock BD (April 2000). "Toxicity of epoxy fatty acids and related compounds to cells expressing human soluble epoxide hydrolase". Chemical Research in Toxicology. 13 (4): 217–26. doi:10.1021/tx990162c. PMID 10775319.
14. Moghaddam MF, Grant DF, Cheek JM, Greene JF, Williamson KC, Hammock BD (May 1997). "Bioactivation of leukotoxins to their toxic diols by epoxide hydrolase". Nature Medicine. 3 (5). Nature Publishing Group: 562–566. doi:10.1038/nm0597-562. PMC 7095900. PMID 9142128.