Orally bioavailable potent soluble epoxide hydrolase inhibitors

Abstract

A series of N,N'-disubstituted ureas having a conformationally restricted cis- or trans-1,4-cyclohexane alpha to the urea were prepared and tested as soluble epoxide hydrolase (sEH) inhibitors. This series of compounds showed low nanomolar to picomolar activities against recombinant human sEH. Both isomers showed similar potencies, but the trans isomers were more metabolically stable in human hepatic microsomes. Furthermore, these new potent inhibitors show a greater metabolic stability in vivo than previously described sEH inhibitors. We demonstrated that trans-4-[4-(3-adamantan-1-ylureido)cyclohexyloxy]benzoic acid 13g (t-AUCB, IC50 = 1.3 +/- 0.05 nM) had excellent oral bioavailability (98%, n = 2) and blood area under the curve in dogs and was effective in vivo to treat hypotension in lipopolysaccharide challenged murine models.

Figure 1

Common inhibitors of sEH. IC₅₀ is for in vitro inhibition of the recombinant human sEH.

Figure 2

General structures of the new series of compounds.

Scheme 1

Synthesis of cis- and trans-1,4-Cyclohexane Based Urea Derivatives^{a a} Reagents and conditions: (a) 1-adamantyl isocyanate, Et₃N, DMF, room temp, 6 h; (b) R₁-PhCH₂Br, NaH, DMF, 0 to room temp, 12 h; (c) Nefken's reagent, K₂CO₃, H₂O, room temp, 30 min; (d) PPh₃, p-nitrobenzoic acid, DIAD, THF, room temp, 12 h; (e) 35% hydrazine, CH₂Cl₂, MeOH, room temp, 1 day; (f) 1-adamantyl isocyanate, DMF, room temp, 12 h; (g) 1 N NaOH, CH₃CN, room temp; (h) NaH, R₂-PhCH₂Br, DMF; (i) R₄-PhOH, PPh₃, DIAD; THF, room temp, 12 h; (j) (i) 1 N NaOH; (ii) Et₃N, MW, 110 °C, DMF, 30 min; (k) R₃-PhOH, PPh₃, DIAD, THF, room temp, 12 h; (l) aqueous 1 N NaOH, CH₃CN, 90 °C, 6 h.

Scheme 2^a

^a Reagents and conditions: (a) 12f (for 19a) or 15f (for 19b,c), DMF, room temp, 12 h; (b) 1 N NaOH, acetonitrile, water, 90 °C, 6 h.

Scheme 3

Synthesis of Amide Derivatives 22 and 23^{a a} Reagents and conditions: (a) 24, EDC, CH₂Cl₂, room temp, 2 h; (b) 15d, EDC, CH₂Cl₂, room temp, 2 h.

Scheme 4

Synthesis of Urea Compounds Having Different Linker in Place of the Cyclohexane^{a a} Reagents and conditions: (a) PhthNCH₂(CH₂)₂CH₂OH (32), DIAD, PPh₃, THF; (b) PhthNCH₂C≡CCH₂OH (33), DIAD, PPh₃, THF; (c) (i) 1-fluoro-4-nitrobenzene, K₂CO₃, DMF, 150 °C; (ii) 10% Pd/C, H₂ (1 atm), EtOAc, room temp; (d) (i) 35% hydrazine, CH₂Cl₂, MeOH, room temp, 1 day; (ii) 1-adamantyl isocyanate, DMF; (e) 1-adamantyl isocyanate, DMF.

Scheme 5

Synthesis of Compounds Having a Carbon Isostere in Place of an Oxygen Atom^{a a} Reagents and conditions: (a) PDC, DMF, room temp, 12 h; (b) n-BuLi, (4-F-Ph)CH₂PPh₃Br, −78 °C to reflux, 12 h; (c) 10% Pd/C, H₂ (1 atm), MeOH, room temp, 2 h.

Figure 3

(a) Superposition of the compounds 13g (green) and 16g (magenta) docked into the active site of human sEH. The residues Tyr⁴⁶⁵ and Leu⁴⁹⁸ are omitted for clarity. (b) H-bonding of 13g with residue Met⁴¹⁸. (c) H-bondings of 16g with residues Arg⁴⁰⁸ and Trp⁵²⁴. Black lines indicate possible hydrogen bonds.

Figure 4

Pharmacokinetic profile data for selected compounds as obtained via oral administration in a canine model. Area under the curve (AUC) was estimated from a plot of inhibitor plasma concentration (nM) versus time (min) following an oral dose of 0.3 mg/kg of the indicated compounds in triglycerides.

Figure 5

LPS exposure produced temporal changes in plasma oxylipins derived from epoxygenase and soluble epoxide hydrolase pathways. (*) Results (average ± SD; n = 4) in LPS-exposed mice treated with vehicle, AUDA-BE, or 13g are depicted as the ratio of (ΣEETs/ΣDHETs)_observed/(ΣEETs/ΣDHETs)_{vehicle only}. Doses are as follows: AUDA-BE, 10 mg/kg; 13g, 1 mg/kg. Only the 8,9-, 11,12-, and 14,15-epoxides and corresponding diols were summed because the 5,6-regioisomer is a poor sEH substrate and spontaneously lactonized.