Vernolic acid (leukotoxin B or isoleukotoxin) 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 Linoleic acid (LA) is an organic compound with the formula . Both alkene groups () are ''cis''. It is a fatty acid sometimes denoted 18:2 (n−6) or 18:2 ''cis''-9,12. A linoleate is a salt or ester of this acid. Linoleic acid is a polyunsat ...

. Vernolic acid was first definitively characterized in 1954 and its

absolute configuration In chemistry, absolute configuration refers to the spatial arrangement of atoms within a molecular entity (or Functional group, group) that is chirality (chemistry), chiral, and its resultant stereochemical description. Absolute configuration is ...

determined in 1966. It is a major component in vernonia oil, which is produced in abundance by the genera '' Vernonia'' and ''

Euphorbia ''Euphorbia'' is a large and diverse genus of flowering plants, commonly called spurge, in the family (biology), family Euphorbiaceae. Euphorbias range from tiny annual plants to large and long-lived trees, with perhaps the tallest being ''Eu ...

'' and is a potentially useful biofeedstock.

Occurrence

Vernonia oil is extracted from the seeds of the '' Vernonia galamensis'' (ironweed), a plant native to eastern

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

. 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 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 Euphorbia, the type genus of the family. Most spurges, such as ''Euphorbia paralias'', ar ...

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 advantage ...

varnish Varnish is a clear Transparency (optics), transparent hard protective coating or film. It is not to be confused with wood stain. It usually has a yellowish shade due to the manufacturing process and materials used, but it may also be pigmente ...

es and

paint Paint is a material or mixture that, when applied to a solid material and allowed to dry, adds a film-like layer. As art, this is used to create an image or images known as a painting. Paint can be made in many colors and types. Most paints are ...

s, and industrial coatings. Its low

viscosity Viscosity is a measure of a fluid's rate-dependent drag (physics), resistance to a change in shape or to movement of its neighboring portions relative to one another. For liquids, it corresponds to the informal concept of ''thickness''; for e ...

recommends its use as a nonvolatile

solvent A solvent (from the Latin language, Latin ''wikt:solvo#Latin, solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a Solution (chemistry), solution. A solvent is usually a liquid but can also be a solid, a gas ...

in oil-based paints 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 Curing (chemistry), cured end products of epoxy Resin, resins. Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers which contain epoxide groups. The epoxide fun ...

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. Soy is a staple crop, the world's most grown legume, and an important animal feed. Soy is a key source o ...

linseed oil Linseed oil, also known as flaxseed oil or flax oil (in its edible form), is a colorless 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 (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 ...

epoxygenase Epoxygenases are a set of membrane-bound, heme-containing cytochrome P450 (CYP450 or just CYP) enzymes that metabolize polyunsaturated fatty acids (PUFAs) to epoxide products that have a range of biological activities. The most thoroughly-studi ...

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

leukocytes White blood cells (scientific name leukocytes), also called immune cells or immunocytes, are cells of the immune system that are involved in protecting the body against both infectious disease and foreign entities. White blood cells are genera ...

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 co ...

. These effects appear due to the conversion of vernolic acid to its dihydroxy counterparts. For instance, (12''S'',13''R'')-EpOME is converted by soluble epoxide hydrolase (sEH) to (12''R'',13''R'')-dihydroxy-9''Z''-octadecenoic acid due to inversion at C12 carbon atom during hydrolysis. A mixture of this dihydroxy acid with its 12''S'',13''S'' enantiomer has been termed isoleukotoxin 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 ).

Related compounds

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

References

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