Arachidonic Acid-metabolizing Cytochrome P450 Enzymes Are Targets of ω-3 Fatty Acids*

Abstract

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) protect against cardiovascular disease by largely unknown mechanisms. We tested the hypothesis that EPA and DHA may compete with arachidonic acid (AA) for the conversion by cytochrome P450 (CYP) enzymes, resulting in the formation of alternative, physiologically active, metabolites. Renal and hepatic microsomes, as well as various CYP isoforms, displayed equal or elevated activities when metabolizing EPA or DHA instead of AA. CYP2C/2J isoforms converting AA to epoxyeicosatrienoic acids (EETs) preferentially epoxidized the -3 double bond and thereby produced 17,18-epoxyeicosatetraenoic (17,18-EEQ) and 19,20-epoxydocosapentaenoic acid (19,20-EDP) from EPA and DHA. We found that these -3 epoxides are highly active as antiarrhythmic agents, suppressing the Ca 2؉ -induced increased rate of spontaneous beating of neonatal rat cardiomyocytes, at low nanomolar concentrations. CYP4A/4F isoforms -hydroxylating AA were less regioselective toward EPA and DHA, catalyzing predominantly -and minus 1 hydroxylation. Rats given dietary EPA/DHA supplementation exhibited substantial replacement of AA by EPA and DHA in membrane phospholipids in plasma, heart, kidney, liver, lung, and pancreas, with less pronounced changes in the brain. The changes in fatty acids were accompanied by concomitant changes in endogenous CYP metabolite profiles (e.g. altering the EET/EEQ/EDP ratio from 87:0:13 to 27:18:55 in the heart). These results demonstrate that CYP enzymes efficiently convert EPA and DHA to novel epoxy and hydroxy metabolites that could mediate some of the beneficial cardiovascular effects of dietary -3 fatty acids.

CYP-13A12 of the nematode Caenorhabditis elegans is a PUFA-epoxygenase involved in behavioural response to reoxygenation

“…For detection and quantification of the metabolites, an online radio flow detector (LB 509; Berthold) was used. Authentic standard compounds were prepared and used as described previously [26,27]. The AA and EPA hydroxylase activities were derived from the sum of 19-/20-HETE (19-/20-hydroxyeicosatetraenoic acid) and 19-/20-HEPE (19-/20-hydroxyeicosapentaenoic acid), respectively, and total AA and EPA epoxygenase activities as the sum of all detectable EETs (epoxyeicosatrienoic acids) and EEQs, respectively.…”

Interaction of brain fatty acid-binding protein with the polyunsaturated fatty acid environment as a potential determinant of poor prognosis in malignant glioma

“…Eicosanoids include prostaglandins (PGs), leukotrienes, epoxyeicosatrienoic acids (EETs) and hydroxyeicosatrienoic acids (HETEs) [76]. Docosanoids include docosatrienes, protectins and resolvins [82][83].…”

“…A report from 30 years ago showed that DHA acts as a potent competitive inhibitor of AA metabolism by COX-2 [115]. More recent reports indicate that DHA also inhibits AA metabolism by CYP epoxygenases and hydroxylases [82]. In brain-metastatic melanoma and in a neuroblastoma cell line [116], DHA competition with AA resulted in decreased PGE 2 levels, with COX-2-mediated DHA metabolite PGE 3 significantly decreasing invasion in a dose-dependent manner [46].…”

“…Others have shown that metabolites derived from AA-COX and AA-LOX were significantly decreased in brain microvessels upon feeding marine fish oil to weanling rats [118]. In light of a recent report indicating that CYP2J2 is 4-fold more active in DHA metabolism than AA metabolism [82], it will be interesting to assess how DHA treatment of FABP7-positive malignant glioma cells affects CYP2J2 activity. These examples demonstrate the complexity of the interrelationship between the molecules and enzymes that utilize and process AA, DHA and their metabolites.…”

Perturbations in Blood Phosphatidylcholine and Sphingomyelin Fatty Acid Composition in a Sample Population of Cigarette Smokers

“…Enzymes of the cytochrome P450 system were found to metabolise AA to epoxyeicosatrienoic acid and hydroxy fatty acids, biologically active compounds with a variety of functions, including vasodilatation, angiogenesis and inflammation resolution, protecting the ischemic myocardium and brain [16][17][18].…”