Optimization of amide-based inhibitors of soluble epoxide hydrolase with improved water solubility

Discovery of the sEH Inhibitor Epoxykynin as a Potent Kynurenine Pathway Modulator

Disease-related phenotypic assays enable unbiased discovery of novel bioactive small molecules and may provide novel insights into physiological systems and unprecedented molecular modes of action (MMOA). Herein, we report the identification and characterization of epoxykynin, a potent inhibitor of the soluble epoxide hydrolase (sEH). Epoxykynin was discovered by means of a cellular assay monitoring modulation of kynurenine (Kyn) levels in BxPC-3 cells upon stimulation with the cytokine interferon-γ (IFN-γ) and subsequent target identification employing affinity-based chemical proteomics. Increased Kyn levels are associated with immune suppression in the tumor microenvironment and, thus, the Kyn pathway and its key player indoleamine 2,3-dioxygenase 1 (IDO1) are appealing targets in immuno-oncology. However, targeting IDO1 directly has led to limited success in clinical investigations, demonstrating that alternative approaches to reduce Kyn levels are in high demand. We uncover a cross-talk between sEH and the Kyn pathway that may provide new opportunities to revert cancer-induced immune tolerance.

Glimepiride, a novel soluble epoxide hydrolase inhibitor, protects against heart failure via increasing epoxyeicosatrienoic acids

BACKGROUND

Epoxyeicosatrienoic acids (EETs), which exert multiple endogenous protective effects, are hydrolyzed into less active dihydroxyeicosatrienoic acids (DHETs) by soluble epoxide hydrolase (sEH). However, commercial drugs related to EETs or sEH are not yet in clinical use.

METHODS

Firstly, the plasma concentration of EETs and DHETs of 316 patients with heart failure (HF) were detected and quantitated by liquid chromatography-tandem mass spectrometry. Then, transverse aortic constriction (TAC)-induced HF was introduced in cardiomyocyte-specific Ephx2-/- mice. Moreover, Western blot, real-time PCR, luciferase reporter, ChIP assays were employed to explore the underlying mechanism. Finally, multiple sEH inhibitors were designed, synthesized, and validated in vitro and in vivo.

RESULTS

The ratios of DHETs/EETs were increased in the plasma from patients with HF. Meanwhile, the expression of sEH was upregulated in the heart of patients and mice with HF, especially in cardiomyocytes. Cardiomyocyte-specific Ephx2-/- mice ameliorated cardiac dysfunction induced by TAC. Consistently, Ephx2 knockdown protected Angiotensin II (AngII)-treated cardiomyocytes via increasing EETs in vitro. Mechanistically, AngII could enhance the expression of transcript factor Krüppel-like factor 15 (KLF15), which in turn upregulated sEH. Importantly, glimepiride was identified as a novel sEH inhibitor, which benefited from the elevated EETs during HF.

CONCLUSIONS

Glimepiride attenuates HF in mice in part by increasing EETs.

CLINICAL TRIAL IDENTIFIER

NCT03461107 (https://clinicaltrials.gov).

Identifying simultaneous matrix metalloproteinases/soluble epoxide hydrolase inhibitors

Matrix metalloproteinase (MMP) and soluble epoxide hydrolase (sEH) have completely unrelated biological functions; however, their dysregulation produce similar effects on biological systems. Based on the similarity in the reported structural requirements for their inhibition, the current study aimed to identify a simultaneous inhibitor for MMP and sEH. Six compounds were identified as potential simultaneous MMP/sEH inhibitors and tested for their capacity to inhibit MMP and sEH. Inhibition of MMP and sEH activity using their endogenous and exogenous substrates was measured by liquid chromatography/mass spectrometry, spectrophotometry, and zymography. Two compounds, CTK8G1143 and ONO-4817, were identified to inhibit both MMP and sEH activity. CTK8G1143 and ONO-4817 inhibited the recombinant human sEH activity by an average of 67.4% and 55.2%, respectively. The IC₅₀ values for CTK8G1143 and ONO-4817 to inhibit recombinant human sEH were 5.2 and 3.5 µM, respectively, whereas their maximal inhibition values were 71.4% and 42.8%, respectively. Also, MMP and sEH activity of human cardiomyocytes were simultaneously inhibited by CTK8G1143 and ONO-4817. Regarding other compounds, they showed either MMP or sEH inhibitory activity but not both. In conclusion, these two simultaneous inhibitors of MMP and sEH could provide a promising intervention for the prevention and control of several diseases, especially cardiovascular diseases.

2-(Piperidin-4-yl)acetamides as Potent Inhibitors of Soluble Epoxide Hydrolase with Anti-Inflammatory Activity

The pharmacological inhibition of soluble epoxide hydrolase (sEH) has been suggested as a potential therapy for the treatment of pain and inflammatory diseases through the stabilization of endogenous epoxyeicosatrienoic acids. Numerous potent sEH inhibitors (sEHI) have been developed, however many contain highly lipophilic substituents limiting their availability. Recently, a new series of benzohomoadamantane-based ureas endowed with potent inhibitory activity for the human and murine sEH was reported. However, their very low microsomal stability prevented further development. Herein, a new series of benzohomoadamantane-based amides were synthetized, fully characterized, and evaluated as sEHI. Most of these amides were endowed with excellent inhibitory potencies. A selected compound displayed anti-inflammatory effects with higher effectiveness than the reference sEHI, TPPU.

Divergent synthesis and elaboration of structure activity relationship for quinoline derivatives as highly selective NTPDase inhibitor

Quinoline derivatives have interesting biological profile. In continuation for the comprehensive evaluations of substituted quinoline derivatives against human nucleoside triphosphate diphosphohydrolases (h-NTPDases) a series of substituted quinoline derivatives (2a-g, 3a-f, 4, 5a-c, 6) was synthesized. The inhibitory activities of the synthesized compounds were evaluated against four isoenzymes of human nucleoside triphosphate diphosphohydrolases (h-NTPDases). These quinoline derivatives had IC₅₀ (µM) values in the range of 0.20-1.75, 0.77-2.20, 0.36-5.50 and 0.90-1.82 for NTPDase1, NTPDase2, NTPDase3 and NTPDase8, respectively. The derivative 3f was the most active compound against NTPDase1 (IC₅₀, 0.20 ± 0.02 µM) that also possessed selectivity towards NTPDase1. Similarly, derivative 3b (IC₅₀, 0.77 ± 0.06), 2h (IC₅₀, 0.36 ± 0.01) and 2c (IC₅₀, 0.90 ± 0.08) displayed excellent activity corresponding to NTPDase2, NTPDase3 and NTPdase8. The compound 5c emerged as a selective inhibitor of NTPDase8. The most active compounds were then investigated to determine their mode of inhibition and finally binding interactions of the active compounds were analyzed through molecular docking studies. The obtained results strongly support the quinoline scaffold's potential as potent and selective NTPDase inhibitor.

Discovery of Soluble Epoxide Hydrolase Inhibitors from Chemical Synthesis and Natural Products

Soluble epoxide hydrolase (sEH) is an α/β hydrolase fold protein and widely distributed in numerous organs including the liver, kidney, and brain. The inhibition of sEH can effectively maintain endogenous epoxyeicosatrienoic acids (EETs) levels and reduce dihydroxyeicosatrienoic acids (DHETs) levels, resulting in therapeutic potentials for cardiovascular, central nervous system, and metabolic diseases. Therefore, since the beginning of this century, the development of sEH inhibitors is a hot research topic. A variety of potent sEH inhibitors have been developed by chemical synthesis or isolated from natural sources. In this review, we mainly summarized the interconnected aspects of sEH with cardiovascular, central nervous system, and metabolic diseases and then focus on representative inhibitors, which would provide some useful guidance for the future development of potential sEH inhibitors.

N-Benzyl-linoleamide, a Constituent of Lepidium meyenii (Maca), Is an Orally Bioavailable Soluble Epoxide Hydrolase Inhibitor That Alleviates Inflammatory Pain

Lepidium meyenii (maca), a plant indigenous to the Peruvian Andes, recently has been utilized globally for claimed health or recreational benefits. The search for natural products that inhibit soluble epoxide hydrolase (sEH), with therapeutically relevant potencies and concentrations, led to the present study on bioactive amide secondary metabolites found in L. meyenii, the macamides. Based on known and suspected macamides, 19 possible macamides were synthesized and characterized. The majority of these amides displayed excellent inhibitory potency (IC50 ≈ 20-300 nM) toward the recombinant mouse, rat, and human sEH. Quantitative analysis of commercial maca products revealed that certain products contain known macamides (1-5, 8-12) at therapeutically relevant total concentrations (≥3.29 mg/g of root), while the inhibitory potency of L. meyenii extracts directly correlates with the sum of concentration/IC50 ratios of macamides present. Considering both its in vitro efficacy and high abundance in commercial products, N-benzyl-linoleamide (4) was identified as a particularly relevant macamide that can be utilized for in vivo studies. Following oral administration in the rat, compound 4 not only displayed acceptable pharmacokinetic characteristics but effectively reduced lipopolysaccharide-induced inflammatory pain. Inhibition of sEH by macamides provides a plausible biological mechanism of action to account for several beneficial effects previously observed with L. meyenii treatments.

Small Molecule Soluble Epoxide Hydrolase Inhibitors in Multitarget and Combination Therapies for Inflammation and Cancer

The enzyme soluble epoxide hydrolase (sEH) plays a central role in metabolism of bioactive lipid signaling molecules. The substrate-specific hydrolase activity of sEH converts epoxyeicosatrienoic acids (EETs) to less bioactive dihydroxyeicosatrienoic acids. EETs exhibit anti-inflammatory, analgesic, antihypertensive, cardio-protective and organ-protective properties. Accordingly, sEH inhibition is a promising therapeutic strategy for addressing a variety of diseases. In this review, we describe small molecule architectures that have been commonly deployed as sEH inhibitors with respect to angiogenesis, inflammation and cancer. We juxtapose commonly used synthetic scaffolds and natural products within the paradigm of a multitarget approach for addressing inflammation and inflammation induced carcinogenesis. Structural insights from the inhibitor complexes and novel strategies for development of sEH-based multitarget inhibitors are also presented. While sEH inhibition is likely to suppress inflammation-induced carcinogenesis, it can also lead to enhanced angiogenesis via increased EET concentrations. In this regard, sEH inhibitors in combination chemotherapy are described. Urea and amide-based architectures feature prominently across multitarget inhibition and combination chemotherapy applications of sEH inhibitors.

Discovery of phthalimide derivatives as novel inhibitors of a soluble epoxide hydrolase

Soluble epoxide hydrolase (sEH) inhibitors are effective in reducing blood pressure, inflammation, and pain in a number of mammalian disease models. As most classical urea-based sEH inhibitors suffer from poor solubility and pharmacokinetic properties, the development of novel sEH inhibitors with an improved pharmacokinetic specification has received a great deal of attention. In this study, a series of amide-based sEH inhibitors bearing a phthalimide ring as the novel secondary pharmacophore (P₂ ) was designed, synthesized, and evaluated. Docking results illustrated that the amide group as the primary pharmacophore (P₁ ) was placed at a suitable distance from the three key amino acids (Tyr383, Tyr466, and Asp335) for an effective hydrogen bonding. In agreement with these findings, most of the newly synthesized compounds demonstrated moderate to high sEH inhibitory activities, relative to 12-(3-adamantan-1-yl-ureido)dodecanoic acid as the reference standard. Compound 12e with a 4-methoxybenzoyl substituent exhibited the highest sEH inhibitory activity, with an IC₅₀ value of 1.06 nM. Moreover, the ADME properties of the compounds were evaluated in silico, and the results revealed appropriate predictions.

Protostane-type triterpenoids as natural soluble epoxide hydrolase inhibitors: Inhibition potentials and molecular dynamics

The inhibition of soluble epoxide hydrolase (sEH) is a promising therapeutic approach to treat inflammation and other disorders. In our present investigation on searching for sEH inhibitors from traditional Chinese medicines, we found that Alisma orientale displayed inhibition of sEH. We constructed a small library of protostane-type triterpenoids (1-25) isolated from A. orientale, and screened their inhibitory activities. Alismanin B (1), 11-deoxy-25-anhydro alisol E (4), 11-deoxy alisol B (5), and 25-O-ethyl alisol A (15) displayed concentration-dependently inhibitory activities against sEH with IC₅₀ values from 3.40 ± 0.57 μM to 9.57 ± 0.88 μM. 11-Deoxy-25-anhydro alisol E (4) and 11-deoxy alisol B (5) were defined as mixed-type competitive inhibitors with Ki values of 12.6 and 3.48 μM, respectively, based on the result of inhibition kinetics. The potential interaction mechanism of 11-deoxy alisol B (5) with sEH was analyzed by molecular docking and molecular dynamics, revealing that amino acid residues Trp336 and Tyr466 were vital for its inhibitory activity.

Novel amide derivatives of 3-phenylglutaric acid as potent soluble epoxide hydrolase inhibitors

Soluble epoxide hydrolase (sEH) enzyme plays an important role in the metabolism of endogenous chemical mediators, epoxyeicosatrienoic acids, which are involved in the regulation of blood pressure and inflammation. According to the pharmacophoric model suggested for sEH inhibitors, some new amide-based derivatives of 3-phenylglutaric acid were designed, synthesized and biologically evaluated. Docking study illustrated that the amide group as a primary pharmacophore had a suitable distance from the three amino acids of Tyr383, Tyr466 and Asp335 for effective hydrogen binding. Most of the compounds showed moderate to high sEH inhibitory activities in in vitro test in comparison with 12-(3-Adamantan-1-yl-ureido)-dodecanoic acid, as a potent urea-based sEH inhibitor. Compound 6o with phenethyl in R position exhibited the highest activity with IC₅₀ value of 0.5 nM. In this study, some new amide-based derivatives of 3-phenylglutaric acid were designed, synthesized and biologically evaluated. Most of the synthesized compounds provided nanomolar range inhibition against sEH enzyme. The best observed IC₅₀ value was 0.5 nM. Incorporating a carboxylic moiety into these structures by forming carboxylate salts would increase the solubility and improving physicochemical properties.

Palladium-Catalyzed Hydroxycarbonylation of (Hetero)aryl Halides for DNA-Encoded Chemical Library Synthesis

A strategy for DNA-compatible, palladium-catalyzed hydroxycarbonylation of (hetero)aryl halides on DNA–chemical conjugates has been developed. This method generally provided the corresponding carboxylic acids in moderate to very good conversions for (hetero)aryl iodides and bromides, and in poor to moderate conversions for (hetero)aryl chlorides. These conditions were further validated by application within a DNA-encoded chemical library synthesis and subsequent discovery of enriched features from the library in selection experiments against two protein targets.

Prospective for cytochrome P450 epoxygenase cardiovascular and renal therapeutics

Therapeutics for arachidonic acid pathways began with the development of non-steroidal anti-inflammatory drugs that inhibit cyclooxygenase (COX). The enzymatic pathways and arachidonic acid metabolites and respective receptors have been successfully targeted and therapeutics developed for pain, inflammation, pulmonary and cardiovascular diseases. These drugs target the COX and lipoxygenase pathways but not the third branch for arachidonic acid metabolism, the cytochrome P450 (CYP) pathway. Small molecule compounds targeting enzymes and CYP epoxy-fatty acid metabolites have evolved rapidly over the last two decades. These therapeutics have primarily focused on inhibiting soluble epoxide hydrolase (sEH) or agonist mimetics for epoxyeicosatrienoic acids (EET). Based on preclinical animal model studies and human studies, major therapeutic indications for these sEH inhibitors and EET mimics/analogs are renal and cardiovascular diseases. Novel small molecules that inhibit sEH have advanced to human clinical trials and demonstrate promise for cardiovascular diseases. Challenges remain for sEH inhibitor and EET analog drug development; however, there is a high likelihood that a drug that acts on this third branch of arachidonic acid metabolism will be utilized to treat a cardiovascular or kidney disease in the next decade.

Discovery of Novel Soluble Epoxide Hydrolase Inhibitors as Potent Vasodilators

In view of the role of sEH (soluble epoxide hydrolase) in hypertension, we have developed a rigorously validated pharmacophore model containing one HBA (Hydrogen Bond Acceptor), two HY (Hydrophobic) and one RA (Ring Aromatic) features. The model was used as a query to search the NCI (National Cancer Institute) and Maybridge database leading to retrieval of many compounds which were sorted on the basis of predicted activity, fit value and Lipinski’s violation. The selected compounds were docked into the active site of enzyme soluble epoxide hydrolase. Potential interactions were observed between the features of the identified hits and the amino acids present in the docking site. The three selected compounds were subjected to in vitro evaluation using enzyme- based assay and the isolated rat aortic model followed by cytotoxicity studies. The results demonstrate that the identified compounds are potent, safe and novel soluble epoxide hydrolase inhibitors.

Expression, purification, and characterisation of human soluble Epoxide Hydrolase (hsEH) and of its functional C-terminal domain

The human soluble Epoxide Hydrolase (hsEH) is an enzyme involved in the hydrolysis of endogenous anti-inflammatory and cardio-protective signalling mediators known as epoxyeicosatrienoic acids (EETs). EETs’ conversion into the corresponding diols by hsEH generates non-bioactive molecules, thereby the enzyme inhibition would be expected to enhance the EETs bioavailability, and their beneficial properties. Numerous inhibitors have been developed to target the enzyme, some of which are showing promising antihypertensive and anti-inflammatory properties in vivo. Thus far, the preparation of the recombinant enzyme for enzymatic and structural in vitro studies has been performed mainly using a baculovirus expression system. More recently, it was reported that the enzyme could be exogenously expressed and isolated from E. coli, although limited amounts of active protein were obtained. We herein describe two novel methods to yield pure recombinant enzyme. The first describes the expression and purification of the full-length enzyme from eukaryotic cells HEK293-F, whilst the second concerns the C-terminal domain of hsEH obtained from the cost-effective and rapid E. coli prokaryotic system. The two methods successfully generated satisfactory amounts of functional enzyme, with virtually identical enzymatic activity. Overall, the protocols described in this paper can be employed for the recombinant expression and purification of active hsEH, to be used in future biomedical investigations and for high-throughput screening of inhibitors for potential use in the treatment of cardiovascular disease.

•

hsEH is a key regulator of cardiovascular homeostasis.

•

A HEK293-F mammalian expression system for hsEH full-length (FL) was developed.

•

An E. coli expression system for the hsEH C-terminal Domain (CTD) was established.

•

Both proteins exhibited the same enzymatic specific activity in vitro.

•

The CTD preparation provides benefits of easy operation, and high yield and purity.

Discovery of polar spirocyclic orally bioavailable urea inhibitors of soluble epoxide hydrolase

Spirocyclic 1-oxa-9-azaspiro[5.5]undecan-4-amine scaffold was explored as a basis for the design of potential inhibitors of soluble epoxide hydrolase (sEH). Synthesis and testing of the initial SAR-probing library followed by biochemical testing against sEH allowed nominating a racemic lead compound (±)-22. The latter showed remarkable (> 0.5 mM) solubility in aqueous phosphate buffer solution, unusually low (for sEH inhibitors) lipophilicity as confirmed by experimentally determined logD_7.4 of 0.99, and an excellent oral bioavailability in mice (as well as other pharmacokinetic characteristics). Individual enantiomer profiling revealed that the inhibitory potency primarily resided with the dextrorotatory eutomer (+)-22 (IC₅₀ 4.99 ± 0.18 nM). For the latter, a crystal structure of its complex with a C-terminal domain of sEH was obtained and resolved. These data fully validate (+)-22 as a new non-racemic advanced lead compound for further development as a potential therapeutic agent for use in such areas as cardiovascular disease, inflammation and pain.

Discovery of novel drug candidates for inhibition of soluble epoxide hydrolase of arachidonic acid cascade pathway implicated in atherosclerosis

Soluble epoxide hydrolase (sEH), a key enzyme belonging to cytochrome P450 pathway of arachidonic acid cascade is a novel therapeutic drug target against atherosclerosis. The enzyme breaks down epoxyeicosatrienoic acid (EETs) to dihydroxy-eicosatrienoic acids (DHETs) and reduces beneficial cardiovascular properties of EETs. Thus, the present work is aimed at identification of potential leads as sEH inhibitors which will sustain the beneficial properties of EETs in vivo. PubChem and ZINC databases were screened for drug-like compounds based on Lipinski's rule of five and in silico toxicity filters. The binding potential of the drug-like compounds with sEH was explored using molecular docking. The top ranked lead (ZINC23099069) showed higher GOLD score compared with that of the control, 12-(3-adamantan-1-yl-ureido)-dodecanoic acid butyl ester (AUDA-BE) and displayed two hydrogen bonds with Tyr383 and His420 and eleven residues involved in hydrophobic interactions with sEH. The apo_sEH and sEH_ZINC23099069 complex showed stable trajectories during 20 ns time scale of molecular dynamics (MD) simulation. Molecular Mechanics Poisson-Boltzmann Surface Area (MM/PBSA) binding free energy analysis showed that electrostatic energy is the driving energy component for interaction of the lead with sEH. These results demonstrate ZINC23099069 to be a promising drug candidate as sEH inhibitor against atherosclerosis instead of the present urea-based inhibitors.

Effects of adamantane alterations on soluble epoxide hydrolase inhibition potency, physical properties and metabolic stability

Adamantyl groups are widely used in medicinal chemistry. However, metabolism limits their usage. Herein, we report the first systematic study of adamantyl ureas and diureas bearing substituents in bridgehead positions of adamantane and/or spacers between urea groups and adamantane group, and tested their effects on soluble epoxide hydrolase inhibitor potency and metabolic stability. Interestingly, the effect on activity against human and murine sEH varied in opposite ways with each new methyl group introduced into the molecule. Compounds with three methyl substituents in adamantane were very poor inhibitors of murine sEH while still very potent against human sEH. In addition, diureas with terminal groups bigger than sEH catalytic tunnel diameter were still good inhibitors suggesting that the active site of sEH opens to capture the substrate or inhibitor molecule. The introduction of one methyl group leads to 4-fold increase in potency without noticeable loss of metabolic stability compared to the unsubstituted adamantane. However, introduction of two or three methyl groups leads to 8-fold and 98-fold decrease in stability in human liver microsomes for the corresponding compounds.

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.

Discovery of enantioselectivity of urea inhibitors of soluble epoxide hydrolase

Soluble epoxide hydrolase (sEH) hydrolyzes epoxyeicosatrienoic acids (EETs) in the metabolic pathway of arachidonic acid and has been considered as an important therapeutic target for chronic diseases such as hypertension, diabetes and inflammation. Although many urea derivatives are known as sEH inhibitors, the enantioselectivity of the inhibitors is not highlighted in spite of the stereoselective hydrolysis of EETs by sEH. In an effort to explore the importance of enantioselectivity in the urea scaffold, a series of enantiomers with the stereocenter adjacent to the urea nitrogen atom were prepared. The selectivity of enantiomers of 1-(α-alkyl-α-phenylmethyl)-3-(3-phenylpropyl)ureas showed wide range differences up to 125 fold with the low IC50 value up to 13 nM. The S-configuration with planar phenyl and small alkyl groups at α-position is crucial for the activity and selectivity. However, restriction of the free rotation of two α-groups with indan-1-yl or 1,2,3,4-tetrahydronaphthalen-1-yl moiety abolishes the selectivity between the enantiomers, despite the increase in activity up to 13 nM. The hydrophilic group like sulfonamido group at para position of 3-phenylpropyl motif of 1-(α-alkyl-α-phenylmethyl-3-(3-phenylpropyl)urea improves the activity as well as enantiomeric selectivity. All these ureas are proved to be specific inhibitor of sEH without inhibition against mEH.

Fragment Screening of Soluble Epoxide Hydrolase for Lead Generation-Structure-Based Hit Evaluation and Chemistry Exploration

Soluble epoxide hydrolase (sEH) is involved in the regulation of many biological processes by metabolizing the key bioactive lipid mediator, epoxyeicosatrienoic acids. For the development of sEH inhibitors with improved physicochemical properties, we performed both a fragment screening and a high-throughput screening aiming at an integrated hit evaluation and lead generation. Followed by a joint dose-response analysis to confirm the hits, the identified actives were then effectively triaged by a structure-based hit-classification approach to three prioritized series. Two distinct scaffolds were identified as tractable starting points for potential lead chemistry work. The oxoindoline series bind at the right-hand side of the active-site pocket with hydrogen bonds to the protein. The 2-phenylbenzimidazole-4-sulfonamide series bind at the central channel with significant induced fit, which has not been previously reported. On the basis of the encouraging initial results, we envision that a new lead series with improved properties could be generated if a vector is found that could merge the cyclohexyl functionality of the oxoindoline series with the trifluoromethyl moiety of the 2-phenylbenzimidazole-4-sulfonamide series.

1,3-Disubstituted and 1,3,3-trisubstituted adamantyl-ureas with isoxazole as soluble epoxide hydrolase inhibitors

Adamantyl ureas are good soluble epoxide hydrolase (sEH) inhibitors; however they have limited solubility and rapid metabolism, thus limiting their usefulness in some therapeutic indications. Herein, we test the hypothesis that nodal substitution on the adamantane will help solubilize and stabilize the compounds. A series of compounds containing adamantane derivatives and isoxazole functional groups were developed. Overall, the presence of methyl on the nodal positions of adamantane yields higher water solubility than previously reported urea-based sEH inhibitors while maintaining high inhibition potency. However, it did not improve microsomal stability.

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.

The 2014 Bernard B. Brodie award lecture-epoxide hydrolases: drug metabolism to therapeutics for chronic pain

Dr. Bernard Brodie's legacy is built on fundamental discoveries in pharmacology and drug metabolism that were then translated to the clinic to improve patient care. Similarly, the development of a novel class of therapeutics termed the soluble epoxide hydrolase (sEH) inhibitors was originally spurred by fundamental research exploring the biochemistry and physiology of the sEH. Here, we present an overview of the history and current state of research on epoxide hydrolases, specifically focusing on sEHs. In doing so, we start with the translational project studying the metabolism of the insect juvenile hormone mimic R-20458 [(E)-6,7-epoxy-1-(4-ethylphenoxy)-3,7-dimethyl-2-octene], which led to the identification of the mammalian sEH. Further investigation of this enzyme and its substrates, including the epoxyeicosatrienoic acids, led to insight into mechanisms of inflammation, chronic and neuropathic pain, angiogenesis, and other physiologic processes. This basic knowledge in turn led to the development of potent inhibitors of the sEH that are promising therapeutics for pain, hypertension, chronic obstructive pulmonary disorder, arthritis, and other disorders.

In vitro inhibitory effects of ethanol extract of Danshen (Salvia miltiorrhiza) and its components on the catalytic activity of soluble epoxide hydrolase

BACKGROUND

Soluble epoxide hydrolase (sEH) has been demonstrated to be a key enzyme involved in the pathologic development of several cardiovascular diseases and inflammation, and inhibition of sEH is therefore very helpful or crucial for the treatment of ischemia-reperfusion injury, cardiac hypertrophy, hypertension and inflammation. Danshen, the dried root of Salvia miltiorrhiza (Fam. Labiatae), has been used for the treatment of cardiovascular and cerebrovascular diseases in China and other countries for hundreds of years. Recent studies indicated that Danshen and its preparations also have potential for the management of inflammation. However, little information is available about the possibility of Danshen and its components on sEH inhibition.

PURPOSE AND METHODS

Danshen extracts and its constituents were tested for sEH inhibition using its physiological substrate, 8,9-EET, based on a LC-MS/MS assay in this study.

RESULTS

Among the tested 15 compounds, tanshinone IIA and cryptotanshinone were found to be the potent (Ki = 0.87 μM) and medium (Ki = 6.7 μM) mixed-type inhibitors of sEH, respectively. Salvianolic acid C (Ki = 8.6 μM) was proved to be a moderate noncompetitive sEH inhibitor. In consistent with the inhibition results of the pure compounds, the 75% ethanol extract of Danshen (EE, IC50 = 86.5 μg/ml) which contained more tanshinone IIA and cryptotanshinone exhibited more potent inhibition on sEH than the water extract (WE, IC50 > 200 μg/ml) or 1 M NaHCO3 (BE, IC50 > 200 μg/ml) extract.

CONCLUSION

These data indicated that using the ethanol fraction of Danshen and increasing the amounts of tanshinone IIA, cryptotanshinone and salvianolic acid C, especially the contents of tanshinone IIA in Danshen extract or preparations to enhance the inhibitory effects on sEH might be efficient ways to improve its cardiovascular protective and anti-inflammatory effects, and that herbal medicines could be an untapped reservoir for sEH-inhibition agents and developing sEH inhibitors from the cardiovascular protective and anti-inflammatory herbs is a promising approach.

Soluble epoxide hydrolase inhibitors and heart failure

Cardiovascular disease remains one of the leading causes of death in the Western societies. Heart failure (HF) is due primarily to progressive myocardial dysfunction accompanied by myocardial remodeling. Once HF develops, the condition is, in most cases, irreversible and is associated with a very high mortality rate. Soluble epoxide hydrolase (sEH) is an enzyme that catalyzes the hydrolysis of epoxyeicosatrienoic acids (EETs), which are lipid mediators derived from arachidonic acid through the cytochrome P450 epoxygenase pathway. EETs have been shown to have vasodilatory, antiinflammatory, and cardioprotective effects. When EETs are hydrolyzed by sEH to corresponding dihydroxyeicosatrienoic acids, their cardioprotective activities become less pronounced. In line with the recent genetic study that has identified sEH as a susceptibility gene for HF, the sEH enzyme has received considerable attention as an attractive therapeutic target for cardiovascular diseases. Indeed, sEH inhibition has been demonstrated to have antihypertensive and antiinflammatory actions, presumably due to the increased bioavailability of endogenous EETs and other epoxylipids, and several potent sEH inhibitors have been developed and tested in animal models of cardiovascular disease including hypertension, cardiac hypertrophy, and ischemia/reperfusion injury. sEH inhibitor treatment has been shown to effectively prevent pressure overload- and angiotensin II-induced cardiac hypertrophy and reverse the pre-established cardiac hypertrophy caused by chronic pressure overload. Application of sEH inhibitors in several cardiac ischemia/reperfusion injury models reduced infarct size and prevented the progressive cardiac remodeling. Moreover, the use of sEH inhibitors prevented the development of electrical remodeling and ventricular arrhythmias associated with cardiac hypertrophy and ischemia/reperfusion injury. The data published to date support the notion that sEH inhibitors may represent a promising therapeutic approach for combating detrimental cardiac remodeling and HF.

Significance of reagent addition sequence in the amidation of carboxylic acids mediated by PPh3 and I2

The outcome of the amidation reaction mediated by PPh₃–I₂ was found to be highly dependent on the addition sequence of the reagents.

14,15-Epoxyeicosa-5,8,11-trienoic Acid (14,15-EET) surrogates: carboxylate modifications

The cytochrome P450 eicosanoid 14,15-epoxyeicosa-5,8,11-trienoic acid (14,15-EET) is a powerful endogenous autacoid that has been ascribed an impressive array of physiologic functions including regulation of blood pressure. Because 14,15-EET is chemically and metabolically labile, structurally related surrogates containing epoxide bioisosteres were introduced and have become useful in vitro pharmacologic tools but are not suitable for in vivo applications. A new generation of EET mimics incorporating modifications to the carboxylate were prepared and evaluated for vasorelaxation and inhibition of soluble epoxide hydrolase (sEH). Tetrazole 19 (ED₅₀ 0.18 μM) and oxadiazole-5-thione 25 (ED₅₀ 0.36 μM) were 12- and 6-fold more potent, respectively, than 14,15-EET as vasorelaxants; on the other hand, their ability to block sEH differed substantially, i.e., 11 vs >500 nM. These data will expedite the development of potent and specific in vivo drug candidates.

Symmetric adamantyl-diureas as soluble epoxide hydrolase inhibitors

A series of inhibitors of the soluble epoxide hydrolase (sEH) containing two urea groups has been developed. Inhibition potency of the described compounds ranges from 2.0 μM to 0.4 nM. 1,6-(Hexamethylene)bis[(adamant-1-yl)urea] (3b) was found to be a potent slow tight binding inhibitor (IC50=0.5 nM) with a strong binding to sEH (Ki=3.1 nM) and a moderately long residence time on the enzyme (koff=1.05 × 10(-3) s(-1); t1/2=11 min).

Design and discovery of soluble epoxide hydrolase inhibitors for the treatment of cardiovascular diseases

INTRODUCTION

Cardiovascular diseases are a leading cause of death in developed countries. Increasing evidence shows that the alteration in the normal functions of the vascular endothelium plays a major role in the development of cardiovascular diseases. However, specific agents designed to prevent endothelial dysfunction and related cardiovascular complications are still lacking. One emerging strategy is to increase the bioavailability of epoxyeicosatrienoic acids (EETs), synthesized by cytochrome P450 epoxygenases from arachidonic acid. EETs are endothelium-derived hyperpolarising and relaxing factors and display attractive anti-inflammatory and metabolic properties. Genetic polymorphism studies in humans, and experiments in animal models of diseases, have identified soluble epoxide hydrolase (sEH), the major enzyme involved in EET degradation, as a potential pharmacological target.

AREAS COVERED

This review presents EET pathway and its functions and summarises the data supporting the development of sEH inhibitors for the treatment of cardiovascular and metabolic diseases. Furthermore, the authors present the different chemical families of sEH inhibitors developed and their effects in animal models of cardiovascular and metabolic diseases.

EXPERT OPINION

Several generations of sEH inhibitors have now been designed to treat endothelial dysfunction and cardiovascular complications for a variety of diseases. The safety of these drugs remains to be carefully investigated, particularly in relation to carcinogenesis. The increasing knowledge of the biological role of each of the EET isomers and of their metabolites may improve their pharmacological profile. This, in turn, could potentially lead to the identification of new pharmacological agents that achieve the cellular effects needed without the deleterious side effects.

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.

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

Substituted ureas with a carboxylic acid ester as a secondary pharmacophore are potent soluble epoxide hydrolase (sEH) inhibitors. Although the ester substituent imparts better physical properties, such compounds are quickly metabolized to the corresponding less potent acids. Toward producing biologically active ester compounds, a series of esters were prepared and evaluated for potency on the human enzyme, stability in human liver microsomes, and physical properties. Modifications around the ester function enhanced in vitro metabolic stability of the ester inhibitors up to 32-fold without a decrease in inhibition potency. Further, several compounds had improved physical properties.

Soluble epoxide hydrolase expression in a porcine model of arteriovenous graft stenosis and anti-inflammatory effects of a soluble epoxide hydrolase inhibitor

Synthetic arteriovenous (AV) grafts, placed between an artery and vein, are used for hemodialysis but often fail due to stenosis, typically at the vein-graft anastomosis. This study recorded T lymphocyte and macrophage accumulation at the vein-graft anastomosis, suggesting a role for inflammation in stenosis development. Epoxyeicosatrienoic acids (EETs), products of cytochrome P-450 epoxidation of arachidonic acid, have vasculoprotective and anti-inflammatory effects including inhibition of platelet activation, cell migration, and adhesion. EETs are hydrolyzed by soluble epoxide hydrolase (sEH) to less active diols. The effects of a specific inhibitor of sEH (sEHI) on cytokine release from human monocytes and mouse bone marrow-derived macrophages (BMMΦ) from wild-type (WT) and sEH knockout (KO) animals were investigated. Expression of sEH protein increased over time at the anastomosis as evaluated by immunohistochemistry. Pre-exposure of adherent human monocytes to sEHI (5 μM) significantly inhibited lipopolysaccharide-induced release of monocyte chemotactic protein-1 (MCP-1) and tumor necrosis factor-α and enhanced the EET-to-diol ratio. Release of MCP-1 from WT BMMΦ was significantly inhibited but release from sEH KO BMMΦ was not attenuated indicating the specificity of the sEHI. In contrast, sEHI did not inhibit the release of macrophage inflammatory protein-1 or interleukin-6. Nuclear translocation of NF-κB, as assessed by immunocytochemical staining, was not decreased with sEHI in monocytes, but the phosphorylation of JNK was completely abrogated, suggesting this pathway is the target of sEHI effects in monocytes. These results suggest that sEHI may be useful for inhibition of inflammation and subsequently stenosis in AV grafts.

Screening a library of 1600 adamantyl ureas for anti-Mycobacterium tuberculosis activity in vitro and for better physical chemical properties for bioavailability

Adamantyl ureas were previously identified as a group of compounds active against Mycobacterium tuberculosis in culture with minimum inhibitor concentrations (MICs) below 0.1 μg/ml. These compounds have been shown to target MmpL3, a protein involved in secretion of trehalose mono-mycolate. They also inhibit both human soluble epoxide hydrolase (hsEH) and M. tuberculosis epoxide hydrolases. However, active compounds to date have high cLogP's and are poorly soluble, leading to low bioavailability and thus limiting any therapeutic application. In this study, a library of 1600 ureas (mostly adamantyl ureas), which were synthesized for the purpose of increasing the bioavailability of inhibitors of hsEH, was screened for activity against M. tuberculosis. 1-Adamantyl-3-phenyl ureas with a polar para substituent were found to retain moderate activity against M. tuberculosis and one of these compounds was shown to be present in serum after oral administration to mice. However, neither it, nor a closely related analog, reduced M. tuberculosis infection in mice. No correlation between in vitro potency against M. tuberculosis and the hsEH inhibition were found supporting the concept that activity against hsEH and M. tuberculosis can be separated. Also there was a lack of correlation with cLogP and inhibition of the growth of M. tuberculosis. Finally, members of two classes of adamantyl ureas that contained polar components to increase their bioavailability, but lacked efficacy against growing M. tuberculosis, were found to taken up by the bacterium as effectively as a highly active apolar urea suggesting that these modifications to increase bioavailability affected the interaction of the urea against its target rather than making them unable to enter the bacterium.

Epoxides and soluble epoxide hydrolase in cardiovascular physiology

Epoxyeicosatrienoic acids (EETs) are arachidonic acid metabolites that importantly contribute to vascular and cardiac physiology. The contribution of EETs to vascular and cardiac function is further influenced by soluble epoxide hydrolase (sEH) that degrades EETs to diols. Vascular actions of EETs include dilation and angiogenesis. EETs also decrease inflammation and platelet aggregation and in general act to maintain vascular homeostasis. Myocyte contraction and increased coronary blood flow are the two primary EET actions in the heart. EET cell signaling mechanisms are tissue and organ specific and provide significant evidence for the existence of EET receptors. Additionally, pharmacological and genetic manipulations of EETs and sEH have demonstrated a contribution for this metabolic pathway to cardiovascular diseases. Given the impact of EETs to cardiovascular physiology, there is emerging evidence that development of EET-based therapeutics will be beneficial for cardiovascular diseases.

Antitumor agents. 289. Design, synthesis, and anti-breast cancer activity in vivo of 4-amino-2H-benzo[h]chromen-2-one and 4-amino-7,8,9,10-tetrahydro-2H-benzo[h]chromen-2-one analogues with improved water solubility

Previously, we reported that 4-amino-2H-benzo[h]chromen-2-one (ABO) and 4-amino-7,8,9,10-tetrahydro-2H-benzo[h]chromen-2-one (ATBO) analogues, which were developed from the lead natural product neo-tanshinlactone, are potent cytotoxic agents. In order to improve on their water solubility, the diamino analogues and related salts were designed. All synthesized compounds were assayed for cytotoxicity, and selected compounds were evaluated for in vivo anti-mammary epithelial proliferation activity in wild-type mice and mice predisposed for mammary tumors due to Brca1/p53 mutations. The new derivatives 10, 16 (ABO), 22, and 27 (ATBO) were the most active analogues, with IC(50) values of 0.038-0.085 μM in the cytotoxicity assay. Analogue 10 showed around 50-fold improved water solubility compared with the prior lead ABO compound 4-[(4'-methoxyphenyl)amino]-2H-benzo[h]chromen-2-one (3). Compounds 3, 4, 10, and 22 significantly reduced overall numbers of mammary cells, as indicated by the reduction of mammary gland branching in mutant mice. A one-week treatment with 10 resulted in 80% reduction in BrdU-positive cells in the cancer prone mammary gland. These four compounds had differential effects on cellular proliferation and apoptosis in wild-type mouse and a mouse model of human breast cancers. Compound 10 merits further development as a promising anticancer clinical trial candidate.

Design, synthesis and evaluation of non-urea inhibitors of soluble epoxide hydrolase

Inhibition of soluble epoxide hydrolase (sEH) has been proposed as a new pharmaceutical approach for treating hypertension and vascular inflammation. The most potent sEH inhibitors reported in literature to date are urea derivatives. However, these compounds have limited pharmacokinetic profiles. We investigated non-urea amide derivatives as sEH inhibitors and identified a potent human sEH inhibitor 14-34 having potency comparable to urea-based inhibitors.