14-15-dihydroxyeicosatrienoic-acid and 1-3-dicyclohexylurea

Cytochrome P450-derived epoxyeicosatrienoic acids (EET) are biologically active metabolites of arachidonic acid that have potent effects on renal vascular reactivity and tubular ion transport and have been implicated in the control of blood pressure. EETs are hydrolyzed to their less active diols, dihydroxyeicosatrienoic acids (DHET), by the enzyme soluble epoxide hydrolase (sEH). 1,3-dicyclohexylurea (DCU), a potent sEH inhibitor, lowers systemic blood pressure in spontaneously hypertensive rats when dosed intraperitoneally. However, DCU has poor aqueous solubility, posing a challenge for in vivo oral delivery. To overcome this limitation, we formulated DCU in a nanosuspension using wet milling. Milling reduced particle size, increasing the total surface area by approximately 40-fold. In rats chronically infused with angiotensin II, the DCU nanosuspension administered orally twice daily for 4 days produced plasma exposures an order of magnitude greater than unmilled DCU and lowered blood pressure by nearly 30 mmHg. Consistent with the mechanism of sEH inhibition, DCU increased plasma 14,15-EET and decreased plasma 14,15-DHET levels. These data confirm the antihypertensive effect of sEH inhibition and demonstrate that greatly enhanced exposure of a low-solubility compound is achievable by oral delivery using a nanoparticle drug delivery system.

Topics: 8,11,14-Eicosatrienoic Acid; Administration, Oral; Animals; Blood Pressure; Chromatography, Liquid; Disease Models, Animal; Epoxide Hydrolases; Hypertension; Male; Nanoparticles; Particle Size; Rats; Rats, Sprague-Dawley; Solubility; Suspensions; Tandem Mass Spectrometry; Urea

Epoxyeicosatrienoic acids (EETs), lipid mediators synthesized from arachidonic acid by cytochrome P-450 epoxygenases, are converted by soluble epoxide hydrolase (SEH) to the corresponding dihydroxyeicosatrienoic acids (DHETs). Originally considered as inactive degradation products of EETs, DHETs have biological activity in some systems. Here we examined the capacity of EETs and DHETs to activate peroxisome proliferator-activated receptor-alpha (PPARalpha). We find that among the EET and DHET regioisomers, 14,15-DHET is the most potent PPARalpha activator in a COS-7 cell expression system. Incubation with 10 microM 14,15-DHET produced a 12-fold increase in PPARalpha-mediated luciferase activity, an increase similar to that produced by the PPARalpha agonist Wy-14643 (20 microM). Although 10 microM 14,15-EET produced a threefold increase in luciferase activity, this was abrogated by the SEH inhibitor dicyclohexylurea. 14-Hexyloxytetradec-5(Z)-enoic acid, a 14,15-EET analog that cannot be converted to a DHET, did not activate PPARalpha. However, PPARalpha was activated by 2-(14,15-epoxyeicosatrienoyl)glycerol, which was hydrolyzed and the released 14,15-EET converted to 14,15-DHET. COS-7 cells incorporated 14,15-[3H]DHET from the medium, and the cells also retained a small amount of the DHET formed during incubation with 14,15-[3H]EET. Binding studies indicated that 14,15-[3H]DHET binds to the ligand binding domain of PPARalpha with a Kd of 1.4 microM. Furthermore, 14,15-DHET increased the expression of carnitine palmitoyltransferase 1A, a PPARalpha-responsive gene, in transfected HepG2 cells. These findings suggest that 14,15-DHET, produced from 14,15-EET by the action of SEH, may function as an endogenous activator of PPARalpha.

Topics: 8,11,14-Eicosatrienoic Acid; Animals; Arachidonic Acids; Carnitine O-Palmitoyltransferase; Cell Line, Tumor; Chlorocebus aethiops; COS Cells; Epoxide Hydrolases; Epoxy Compounds; Humans; PPAR alpha; Urea