Biologically active ester derivatives as potent inhibitors of the soluble epoxide hydrolase

Intensification of Double Kinetic Resolution of Chiral Amines and Alcohols via Chemoselective Formation of a Carbonate-Enzyme Intermediate

Chiral amines and alcohols are synthons of numerous pharmaceutically-relevant compounds. The previously developed enzymatic kinetic resolution approaches utilize a chiral racemic molecule and achiral acyl donor (or acyl acceptor). Thus, only one enantiodivergent step of the catalytic cycle is engaged, which does not fully exploit the enzyme’s abilities. The first carbonate-mediated example of simultaneous double chemoselective kinetic resolution of chiral amines and alcohols is described. Herein, we established a biocatalytic approach towards four optically-pure compounds (>99% ee, Enantioselectivity: E > 200) via double enzymatic kinetic resolution, engaging chiral organic carbonates as acyl donors. High enantioselectivity was ensured by extraordinary chemoselectivity in lipase-catalyzed formation of unsymmetrical organic carbonates and engaged in a process applicable for the synthesis of enantiopure organic precursors of valuable compounds. This study focused not only on preparative synthesis, but additionally the catalytic mechanism was discussed and the clear impact of this rarely observed carbonate-derived acyl enzyme was shown. The presented protocol is characterized by atom efficiency, acyl donor sustainability, easy acyl group removal, mild reaction conditions, and biocatalyst recyclability, which significantly decreases the cost of the reported process.

Exploring the size of the lipophilic unit of the soluble epoxide hydrolase inhibitors

Soluble epoxide hydrolase (sEH) inhibitors are potential drugs for several diseases. Adamantyl ureas are excellent sEH inhibitors but have limited metabolic stability. Herein, we report the effect of replacing the adamantane group by alternative polycyclic hydrocarbons on sEH inhibition, solubility, permeability and metabolic stability. Compounds bearing smaller or larger polycyclic hydrocarbons than adamantane yielded all good inhibition potency of the human sEH (0.4 ≤ IC₅₀ ≤ 21.7 nM), indicating that sEH is able to accommodate inhibitors of very different size. Human liver microsomal stability of diamantane containing inhibitors is lower than that of their corresponding adamantane counterparts.

Investigation of the binding mode of 1, 3, 4-oxadiazole derivatives as amide-based inhibitors for soluble epoxide hydrolase (sEH) by molecular docking and MM-GBSA

The soluble epoxide hydrolase (sEH) enzyme plays an important role in the metabolism of endogenous chemical mediators involved in the regulation of blood pressure and inflammation. Inhibition of sEH provides a new approach to the treatment of inflammation, hypertension and atherosclerosis. In this study, the binding modes and inhibition mechanisms of the new oxadiazole-based amide inhibitors of the human soluble epoxide hydrolase were investigated by molecular docking and molecular dynamics (MD) simulation followed by the MM-GBSA method to calculate the binding free energy of each inhibitor to sEH. The results obtained from the binding free energy (ΔG _binding) calculation and normal mode analysis indicate that the major favorable contributors are the van der Waals and electrostatic terms, whereas the polar solvation term opposes binding. In addition, a good agreement between the calculated ΔG _binding and the experimental IC₅₀ was obtained [correlation coefficient, r ² = 0.89 (with) and 0.87 (without) entropy]. Besides, comparison of the enthalpy changes (ΔG _MM-GBSA) with entropy changes (-TΔS) indicates that binding process of all inhibitors to sEH is enthalpy-driven. Based on the ΔG _binding on per residue decomposition, Asp335 and Tyr383 residues from the active site and Trp336, Leu499 and His524 residues from hydrophobic pockets contribute the most to ΔG _binding. Moreover, hydrogen bond analysis reveals that Tyr383, Tyr466 and Asp335 residues have an important role in the binding to inhibitors by forming hydrogen bonds with high occupancies. Our obtained results are useful for the understanding of the sEH-inhibitor interactions and may have great importance in the design of future sEH inhibitors.

Rational Design of Potent and Selective Inhibitors of an Epoxide Hydrolase Virulence Factor from Pseudomonas aeruginosa

The virulence factor cystic fibrosis transmembrane conductance regulator (CFTR) inhibitory factor (Cif) is secreted by Pseudomonas aeruginosa and is the founding member of a distinct class of epoxide hydrolases (EHs) that triggers the catalysis-dependent degradation of the CFTR. We describe here the development of a series of potent and selective Cif inhibitors by structure-based drug design. Initial screening revealed 1a (KB2115), a thyroid hormone analog, as a lead compound with low micromolar potency. Structural requirements for potency were systematically probed, and interactions between Cif and 1a were characterized by X-ray crystallography. On the basis of these data, new compounds were designed to yield additional hydrogen bonding with residues of the Cif active site. From this effort, three compounds were identified that are 10-fold more potent toward Cif than our first-generation inhibitors and have no detectable thyroid hormone-like activity. These inhibitors will be useful tools to study the pathological role of Cif and have the potential for clinical application.

Effect of a Soluble Epoxide Hydrolase Inhibitor, UC1728, on LPS-Induced Uveitis in the Rabbit

Cytochrome P450 epoxygenase isozymes convert free arachidonic acid into eicosanoids named epoxyeicosatrienoic acids (EETs) that have roles in regulating inflammation. EETs are rapidly converted to dihydroxyeicosatrienoic acids (DiHETs) by soluble epoxide hydrolase (sEH). Little is known about the potential role of these metabolites in uveitis, but conversion of EETs to DiHETs could contribute to the inflammation. We tested a potent and orally available inhibitor of sEH for its ability to reduce ocular inflammation in a rabbit LPS-induced model of uveitis. Rabbits were treated by subcutaneous injection with the sEH inhibitor (UC1728, 3 mg/kg), or the vehicle control (PEG400) and uveitis was assessed at 6, 24 and 48 h post-intracameral LPS injection using a modified Hackett-McDonald scoring system. Eyes treated by intra-cameral injection of PBS, or by aseptic preparation served as further controls. Signs of inflammation in this model were mild and transient. Treatment with UC1728 did not significantly reduce inflammation compared to animals treated with the PEG400 vehicle. Blood levels of UC1728 were a thousand fold higher than the in vitro determined inhibitory potency (IC50) of the compound suggesting a significant degree of inhibition of sEH in the rabbit. The lack of efficacy suggests that sEH or its substrates the EETs may not be involved in mediating inflammation in this model of uveitis.

Structure-activity relationships of amide-phosphonate derivatives as inhibitors of the human soluble epoxide hydrolase

Structure-activity relationships of amide-phosphonate derivatives as inhibitors of the human soluble epoxide hydrolase (sEH) were investigated. First, a series of alkyl or aryl groups were substituted on the carbon alpha to the phosphonate function in amide compounds to see whether substituted phosphonates can act as a secondary pharmacophore. A tert-butyl group (16) on the alpha carbon was found to yield most potent inhibition on the target enzyme. A 4-50-fold drop in inhibition was induced by other substituents such as aryls, substituted aryls, cycloalkyls, and alkyls. Then, the modification of the O-substituents on the phosphonate function revealed that diethyl groups (16 and 23) were preferable for inhibition to other longer alkyls or substituted alkyls. In amide compounds with the optimized diethylphosphonate moiety and an alkyl substitution such as adamantane (16), tetrahydronaphthalene (31), or adamantanemethane (36), highly potent inhibitions were gained. In addition, the resulting potent amide-phosphonate compounds had reasonable water solubility, suggesting that substituted phosphonates in amide inhibitors are effective for both inhibition potency on the human sEH and water solubility as a secondary pharmacophore.

Structure-activity relationships of substituted oxyoxalamides as inhibitors of the human soluble epoxide hydrolase

We explored both structure-activity relationships among substituted oxyoxalamides used as the primary pharmacophore of inhibitors of the human sEH and as a secondary pharmacophore to improve water solubility of inhibitors. When the oxyoxalamide function was modified with a variety of alkyls or substituted alkyls, compound 6 with a 2-adamantyl group and a benzyl group was found to be a potent sEH inhibitor, suggesting that the substituted oxyoxalamide function is a promising primary pharmacophore for the human sEH, and compound 6 can be a novel lead structure for the development of further improved oxyoxalamide or other related derivatives. In addition, introduction of substituted oxyoxalamide to inhibitors with an amide or urea primary pharmacophore produced significant improvements in inhibition potency and water solubility. In particular, the N,N,O-trimethyloxyoxalamide group in amide or urea inhibitors (26 and 31) was most effective among those tested for both inhibition and solubility. The results indicate that substituted oxyoxalamide function incorporated into amide or urea inhibitors is a useful secondary pharmacophore, and the resulting structures will be an important basis for the development of bioavailable sEH inhibitors.

Design, synthesis and biological evaluation of 4-benzamidobenzoic Acid hydrazide derivatives as novel soluble epoxide hydrolase inhibitors

Inhibitors of soluble epoxide hydrolase (sEH) represent one of the novel pharmaceutical approaches for treating hypertension, vascular inflammation, pain and other cardiovascular related diseases. Most of the potent sEH inhibitors reported in literature often suffer from poor solubility and bioavailability. Toward improving pharmacokinetic profile beside favorable potency, two series of 4-benzamidobenzoic acid hydrazide derivatives with hydrazide group as a novel secondary pharmacophore against sEH enzyme were developed. The designed compounds were synthesized in acceptable yield and their in vitro assay was determined. Most of the synthesized compounds have appropriate physical properties and exhibited considerable in-vitro sEH inhibitory activity in comparison with 12-(3-Adamantan-1-yl-ureido)- dodecanoicacid (AUDA), a potent urea-based sEH inhibitor. 4-(2-(4-(4-chlorobenzamido) benzoyl)hydrazinyl)-4-oxobutanoic acid 6c was found to be the most potent inhibitor with inhibitory activity of 72% targeting sEH enzyme.