A series of 1,3-disubstituted ureas possessing a piperidyl moiety has been synthesized to investigate their structure-activity relationships as inhibitors of the human and murine soluble epoxide hydrolase (sEH). Oral administration of thirteen 1-aryl-3-(1-acylpiperidin-4-yl)urea inhibitors in mice revealed substantial improvements in pharmacokinetic parameters over previously reported 1-adamantyl-urea based inhibitors. For example, 1-(1-(cyclopropanecarbonyl)piperidin-4-yl)-3-(4-(trifluoromethoxy)phenyl)urea (52) showed a 7-fold increase in potency, a 65-fold increase in Cmax† and a 3300 fold increase in AUC over its adamantane analogue 1-(1-adamantyl)-3-(1-propionylpiperidin-4-yl)urea (2). This novel sEH inhibitor showed a 1000 fold increase in potency when compared to morphine by reducing hyperalgesia as measured by mechanical withdrawl threshold using the in vivo carrageenan induced inflammatory pain model.

Pain is a major health concern even though numerous analgesic agents are available. Side effects and lack of wide-spectrum efficacy of current drugs justify efforts to better understand pain mechanisms. Stabilization of natural epoxy-fatty acids (EFAs) through inhibition of the soluble epoxide hydrolase (sEH) reduces pain. However, in the absence of an underlying painful state, inhibition of sEH is ineffective. Surprisingly, a pain-mediating second messenger, cAMP, interacts with natural EFAs and regulates the analgesic activity of sEH inhibitors. Concurrent inhibition of sEH and phosphodiesterase (PDE) dramatically reduced acute pain in rodents. Our findings demonstrate a mechanism of action of cAMP and EFAs in the pathophysiology of pain. Furthermore, we demonstrate that inhibition of various PDE isozymes, including PDE4, lead to significant increases in EFA levels through a mechanism independent of sEH, suggesting that the efficacy of commercial PDE inhibitors could result in part from increasing EFAs. The cross-talk between the two major pathways-one mediated by cAMP and the other by EFAs-paves the way to new approaches to understand and control pain.nociception | antinociceptive | epoxyeicosatrienoic acid

Soluble epoxide hydrolase inhibitors (sEHIs) are anti-inflammatory, analgesic, anti-hypertensive, cardio- and renal-protective in multiple animal models. However, the earlier adamantyl-containing urea-based inhibitors are rapidly metabolized. Therefore, new potent inhibitors with the adamantyl group replaced by a substituted phenyl group were synthesized to presumptively offer better pharmacokinetic (PK) properties.. Here we describe the improved PK profile of these inhibitors and the anti-inflammatory effect of the most promising one in a murine model. The PK profiles of inhibitors were determined following p.o. administration and serial bleeding in mice. The anti-inflammatory effect of 1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl)urea(TPPU), the most promising inhibitor among the five sEHIs tested, was investigated in a lipopolysaccharide (LPS)-challenged murine model. The earlier broadly-used adamantyl-containing sEHI, trans-4-[4-(3-adamantan-1-yl-ureido)-cyclohexyloxy]-benzoic acid (t-AUCB), was used for comparison. Compared with the earlier adamantyl-containing urea-based inhibitors, substituted phenyl-containing urea-based inhibitors afford more favorable PK properties, such as higher Cmaxs, larger AUCs and longer t1/2s, which, as expected, show more stable metabolic stability. Moreover, oral administration of TPPU dramatically reversed the shifts caused by LPS-challenge in plasma levels of inflammatory cytokines, epoxides and corresponding diols, which is more potent than t-AUCB. The substituted phenyl-containing sEHIs are more metabolically stable than those with adamantyl group, resulting in more potent efficacy in vivo. This indicates a new strategy for development of sEHIs for further study toward clinical trials.

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ABSTRACT:Triclocarban (3,4,4-trichlorocarbanilide, TCC) is a widely used antibacterial agent in personal care products and is frequently detected as an environmental pollutant in waste waters and surface waters. In this study, we report novel reactive metabolites potentially formed during biotransformation of TCC. The oxidative metabolism of TCC has been predicted using an electrochemical cell coupled online to liquid chromatography and electrospray ionization mass spectrometry. The electrochemical oxidation unveils the fact that hydroxylated metabolites of TCC may form reactive quinone imines. Moreover, a so-far unknown dechlorinated and hydroxylated TCC metabolite has been identified. The results were confirmed by in vitro studies with human and rat liver microsomes. The reactivity of the newly discovered quinone imines was demonstrated by their covalent binding to glutathione and macromolecules, using ␤-lactoglobulin A as a model protein. The results regarding the capability of the electrochemical cell to mimic the oxidative metabolism of TCC are discussed. Moreover, the occurrence of reactive metabolites is compared with findings from earlier in vivo studies and their relevance in vivo is argued.