Vernolic acid (leukotoxin) is a

long chain fatty acid In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated and unsaturated compounds#Organic chemistry, saturated or unsaturated. Most naturally occurring fatty acids have an B ...

that is

monounsaturated In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food. The term often refers specifically to triglycerides (triple est ...

and contains an

epoxide In organic chemistry, an epoxide is a cyclic ether () with a three-atom ring. This ring approximates an equilateral triangle, which makes it strained, and hence highly reactive, more so than other ethers. They are produced on a large scale for ...

. It is the R,R-''cis'' epoxide derived from the C12–C13 alkene of

linoleic acid Linoleic acid (LA) is an organic compound with the formula COOH(CH2)7CH=CHCH2CH=CH(CH2)4CH3. Both alkene groups are cis-trans isomerism, ''cis''. It is a fatty acid sometimes denoted 18:2 (n-6) or 18:2 ''cis''-9,12. A linoleate is a salt (chem ...

. Vernolic acid was first definitively characterized in 1954. It is a major component in vernonia oil, which is produced in abundance by the genera

Vernonia ''Vernonia'' is a genus of about 350 species of forbs and shrubs in the Daisy family Asteraceae. Some species are known as ironweed. Some species are edible and of economic value. They are known for having intense purple flowers. There have been ...

and

Euphorbia ''Euphorbia'' is a very large and diverse genus of flowering plants, commonly called spurge, in the family Euphorbiaceae. "Euphorbia" is sometimes used in ordinary English to collectively refer to all members of Euphorbiaceae (in deference to t ...

and is a potentially useful biofeedstock.

Occurrence

Vernonia oil is extracted from the seeds of the ''

Vernonia galamensis ''Vernonia galamensis'' is a plant in the sunflower family, known for its use as an oilseed. This species, often called ironweed, is the largest source of vernonia oil, which is rich in a useful epoxy fatty acid called vernolic acid and is us ...

'' (ironweed), a plant native to eastern

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

. 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 ''

'', '' Stokesia'', ''

Crepis ''Crepis'', commonly known in some parts of the world as hawksbeard or hawk's-beard (but not to be confused with the related genus ''Hieracium'' with a similar common name), is a genus of annual and perennial flowering plants of the family Aster ...

'' (from the daisy family), and ''

lagascae'' and '' Bernardia pulchella'' from the

Euphorbiaceae Euphorbiaceae, the spurge family, is a large family of flowering plants. In English, they are also commonly called euphorbias, which is also the name of a genus in the family. Most spurges, such as ''Euphorbia paralias'', are herbs, but some, e ...

Potential applications

Vernonia oil has been proposed as a precursor to

adhesive Adhesive, also known as glue, cement, mucilage, or paste, is any non-metallic substance applied to one or both surfaces of two separate items that binds them together and resists their separation. The use of adhesives offers certain advant ...

varnish Varnish is a clear transparent hard protective coating or film. It is not a stain. It usually has a yellowish shade from the manufacturing process and materials used, but it may also be pigmented as desired, and is sold commercially in various ...

es and

paint Paint is any pigmented liquid, liquefiable, or solid mastic composition that, after application to a substrate in a thin layer, converts to a solid film. It is most commonly used to protect, color, or provide texture. Paint can be made in many ...

s, and industrial coatings. Its low

viscosity The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the inte ...

recommends its use as a nonvolatile

solvent A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...

oil-based paint Oil paint is a type of slow-drying paint that consists of particles of pigment suspended in a drying oil, commonly linseed oil. The viscosity of the paint may be modified by the addition of a solvent such as turpentine or white spirit, and varnis ...

s since it will become incorporated in the dry paint rather than evaporating into the air.'' In its application as an

epoxy Epoxy is the family of basic components or cured end products of epoxy resins. Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers which contain epoxide groups. The epoxide functional group is also coll ...

oil, vernonia oil competes with

soybean The soybean, soy bean, or soya bean (''Glycine max'') is a species of legume native to East Asia, widely grown for its edible bean, which has numerous uses. Traditional unfermented food uses of soybeans include soy milk, from which tofu an ...

linseed oil Linseed oil, also known as flaxseed oil or flax oil (in its edible form), is a colourless to yellowish oil obtained from the dried, ripened seeds of the flax plant (''Linum usitatissimum''). The oil is obtained by pressing, sometimes followed by ...

, which supply most of the market for these applications. Its low

makes it more desirable than fully epoxidized linseed or soybean oils. It is comparable to partially epoxidized linseed or soybean oil.

Toxicity

In a variety of mammalian species, vernolic acid is made by the metabolism of

cytochrome P450 Cytochromes P450 (CYPs) are a Protein superfamily, superfamily of enzymes containing heme as a cofactor (biochemistry), cofactor that functions as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are ...

epoxygenase Epoxygenases are a set of membrane-bound, heme-containing cytochrome P450 (CYP P450 or just CYP) enzymes that metabolize polyunsaturated fatty acids to epoxide products that have a range of biological activities. The most thoroughly studied substr ...

enzymes; under these circumstances it is termed leukotoxin because of its toxic effects on

leukocytes White blood cells, also called leukocytes or leucocytes, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and derived from mult ...

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 Acute respiratory distress syndrome (ARDS) is a type of respiratory failure characterized by rapid onset of widespread inflammation in the lungs. Symptoms include shortness of breath (dyspnea), rapid breathing (tachypnea), and bluish skin colo ...

. These effects appear due to the conversion of vernolic acid to its dihydroxy counterparts, 12''S'',13''R''- and 12''R'',13''S''-dihydroxy-''cis''-9-octadecenoic acids by

soluble epoxide hydrolase Soluble epoxide hydrolase (sEH) is a bifunctional enzyme that in humans is encoded by the EPHX2 gene. sEH is a member of the epoxide hydrolase family. This enzyme, found in both the cytosol and peroxisomes, binds to specific epoxides and converts ...

(this dihydroxy mixture has been termed leukotoxin diol). 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

subsection on linoleic acid).

Related compounds

coronaric acid Coronaric acid (isoleukotoxin) is a mono-unsaturated, epoxide derivative of the di-saturated fatty acid, linoleic acid (i.e. 9(''Z''),12(''Z'') octadecadienoic acid. It is a mixture of the two optically active isomers of 12(''Z'') 9,10-epoxy-octa ...

, C9-C10 epoxide of linoleic acid.

References

{{reflist, 33em Vegetable oils Fatty acids Epoxides Alkenoic acids