Hepoxilins are nonclassic eicosanoid

Nonclassic eicosanoid

Nonclassic eicosanoids are biologically active signaling molecules made by oxygenation of twenty-carbon fatty acids other than the classic eicosanoids.-Terminology:"Eicosanoid" is the collective...

 hormones involved in inflammation

Inflammation

Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...

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Biochemistry

They derive from arachidonic acid

Arachidonic acid

Arachidonic acid is a polyunsaturated omega-6 fatty acid 20:4.It is the counterpart to the saturated arachidic acid found in peanut oil, Arachidonic acid (AA, sometimes ARA) is a polyunsaturated omega-6 fatty acid 20:4(ω-6).It is the counterpart to the saturated arachidic acid found in peanut oil,...

 via oxidation by the enzyme 12-lipoxygenase

Lipoxygenase

Lipoxygenases are a family of iron-containing enzymes that catalyse the dioxygenation of polyunsaturated fatty acids in lipids containing a cis,cis-1,4- pentadiene structure. It catalyses the following reaction:...

. Hepoxilins are differentiated from closely related eicosanoids, the leukotriene

Leukotriene

Leukotrienes are fatty signaling molecules. They were first found in leukocytes . One of their roles is to trigger contractions in the smooth muscles lining the trachea; their overproduction is a major cause of inflammation in asthma and allergic rhinitis...

s and the lipoxin

Lipoxin

Lipoxins are a series of anti-inflammatory mediators. Lipoxins are short lived endogenously produced nonclassic eicosanoids whose appearance in inflammation signals the resolution of inflammation....

s, in that hepoxilins have no conjugated double bonds.
Corresponding trioxlins A4 and B4 are formed by the same pathway from EPA

Eicosapentaenoic acid

Eicosapentaenoic acid is an omega-3 fatty acid. In physiological literature, it is given the name 20:5. It also has the trivial name timnodonic acid...

Physiological effect

In the skin, Hx are pro-inflammatory, but in neutrophils they are anti-inflammatory.
Hx are potent insulin secretagogues.
One hepoxilin, HepA3, mediates neutrophil migration across the intestines.
Hepoxilins are also produced in the brain.
Cells under oxidative stress secrete HX₃, which in turn upregulates peroxidase

Peroxidase

Peroxidases are a large family of enzymes that typically catalyze a reaction of the form:For many of these enzymes the optimal substrate is hydrogen peroxide, but others are more active with organic hydroperoxides such as lipid peroxides...

, decreasing oxidative stress.
This is proposed to
constitute a compensatory defense response to protect the vitality and functionality of the cell.