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

The Inhibition Activity of Natural Methoxyflavonoid from Inula britannica on Soluble Epoxide Hydrolase and NO Production in RAW264.7 Cells

Soluble epoxide hydrolase (sEH) is an enzyme targeted for the treatment of inflammation and cardiovascular diseases. Activated inflammatory cells produce nitric oxide (NO), which induces oxidative stress and exacerbates inflammation. We identify an inhibitor able to suppress sEH and thus NO production. Five flavonoids 1-5 isolated from Inula britannica flowers were evaluated for their abilities to inhibit sEH with IC50 values of 12.1 ± 0.1 to 62.8 ± 1.8 µM and for their effects on enzyme kinetics. A simulation study using computational chemistry was conducted as well. Furthermore, five inhibitors (1-5) were confirmed to suppress NO levels at 10 µM. The results showed that flavonoids 1-5 exhibited inhibitory activity in all tests, with compound 3 exhibiting the most significant efficacy. Thus, in the development of anti-inflammatory inhibitors, compound 3 is a promising natural candidate.

The involvement of soluble epoxide hydrolase in the development of cardiovascular diseases through epoxyeicosatrienoic acids

Arachidonic acid (AA) has three main metabolic pathways: the cycloxygenases (COXs) pathway, the lipoxygenases (LOXs) pathway, and the cytochrome P450s (CYPs) pathway. AA produces epoxyeicosatrienoic acids (EETs) through the CYPs pathway. EETs are very unstable in vivo and can be degraded in seconds to minutes. EETs have multiple degradation pathways, but are mainly degraded in the presence of soluble epoxide hydrolase (sEH). sEH is an enzyme of bifunctional nature, and current research focuses on the activity of its C-terminal epoxide hydrolase (sEH-H), which hydrolyzes the EETs to the corresponding inactive or low activity diol. Previous studies have reported that EETs have cardiovascular protective effects, and the activity of sEH-H plays a role by degrading EETs and inhibiting their protective effects. The activity of sEH-H plays a different role in different cells, such as inhibiting endothelial cell proliferation and migration, but promoting vascular smooth muscle cell proliferation and migration. Therefore, it is of interest whether the activity of sEH-H is involved in the initiation and progression of cardiovascular diseases by affecting the function of different cells through EETs.

An analysis of omega-3 clinical trials and a call for personalized supplementation for dementia prevention

INTRODUCTION

Targeted interventions are needed to delay or prevent the onset of neurodegenerative diseases. Poor dietary habits are associated with cognitive decline, highlighting the benefits of a healthy diet with fish and polyunsaturated fatty acids (PUFAs). Intake of omega-3 PUFAs docosahexaenoic acid (DHA), α-linolenic acid (ALA) and eicosapentaenoic acid (EPA) is linked with healthy aging, cardiovascular benefits, and reduced risk of Alzheimer's disease. Although omega-3 has health benefits, its intake is often inadequate and insufficient in modern diets. Although fish oil supplements offer an alternative source, inconsistent results from clinical trials raise questions about the factors determining their success.

AREAS COVERED

In this this review, the authors discuss the aforementioned determining factors and highlight strategies that could enhance the effectiveness of omega-3 PUFAs interventions for dementia and cognitive decline. Moreover, the authors provide suggestions for potential future research.

EXPERT OPINION

Factors such as diet, lifestyle, and genetic predisposition can all influence the effectiveness of omega-3 supplementation. When implementing clinical trials, it is crucial to consider these factors and recognize their potential impact on the interpretation of results. It is important to study each variable independently and the interactions between them.

Enhancing cancer immunotherapy via inhibition of soluble epoxide hydrolase

Cancer therapy, including immunotherapy, is inherently limited by chronic inflammation-induced tumorigenesis and toxicity within the tumor microenvironment. Thus, stimulating the resolution of inflammation may enhance immunotherapy and improve the toxicity of immune checkpoint inhibition (ICI). As epoxy-fatty acids (EpFAs) are degraded by the enzyme soluble epoxide hydrolase (sEH), the inhibition of sEH increases endogenous EpFA levels to promote the resolution of cancer-associated inflammation. Here, we demonstrate that systemic treatment with ICI induces sEH expression in multiple murine cancer models. Dietary omega-3 polyunsaturated fatty acid supplementation and pharmacologic sEH inhibition, both alone and in combination, significantly enhance anti-tumor activity of ICI in these models. Notably, pharmacological abrogation of the sEH pathway alone or in combination with ICI counter-regulates an ICI-induced pro-inflammatory and pro-tumorigenic cytokine storm. Thus, modulating endogenous EpFA levels through dietary supplementation or sEH inhibition may represent a unique strategy to enhance the anti-tumor activity of paradigm cancer therapies.

1,3-Dichloroadamantyl-Containing Ureas as Potential Triple Inhibitors of Soluble Epoxide Hydrolase, p38 MAPK and c-Raf

Soluble epoxide hydrolase (sEH) is an enzyme involved in the metabolism of bioactive lipid signaling molecules. sEH converts epoxyeicosatrienoic acids (EET) to virtually inactive dihydroxyeicosatrienoic acids (DHET). The first acids are "medicinal" molecules, the second increase the inflammatory infiltration of cells. Mitogen-activated protein kinases (p38 MAPKs) are key protein kinases involved in the production of inflammatory mediators, including tumor necrosis factor-α (TNF-α) and cyclooxygenase-2 (COX-2). p38 MAPK signaling plays an important role in the regulation of cellular processes, especially inflammation. The proto-oncogenic serine/threonine protein kinase Raf (c-Raf) is a major component of the mitogen-activated protein kinase (MAPK) pathway: ERK1/2 signaling. Normal cellular Raf genes can also mutate and become oncogenes, overloading the activity of MEK1/2 and ERK1/2. The development of multitarget inhibitors is a promising strategy for the treatment of socially dangerous diseases. We synthesized 1,3-disubstituted ureas and diureas containing a dichloroadamantyl moiety. The results of computational methods show that soluble epoxide hydrolase inhibitors can act on two more targets in different signaling pathways of mitogen-activated protein kinases p38 MAPK and c-Raf. The two chlorine atoms in the adamantyl moiety may provide additional Cl-π interactions in the active site of human sEH. Molecular dynamics studies have shown that the stability of ligand-protein complexes largely depends on the "spacer effect." The compound containing a bridge between the chloroadamantyl fragment and the ureide group forms more stable ligand-protein complexes with sEH and p38 MAPK, which indicates a better conformational ability of the molecule in the active sites of these targets. In turn, a compound containing two chlorine atoms forms a more stable complex with c-Raf, probably due to the presence of additional halogen bonds of chlorine atoms with amino acid residues.

Effect of the sEH inhibitor AUDA on arachidonic acid metabolism and NF-κB signaling of rats with postpartum depression-like behavior

OBJECTIVE

To investigate whether sEH inhibitor AUDA can mitigate postpartum depression (PPD)-like symptoms in the rat model and regulate the AA/NF-κB pathway to suppress the inflammatory response in the prefrontal lobes of PPD rats.

METHODS

Five groups of Sprague Dawley rats were used: normal, sham operated, PPD model, AUDA, and paroxetine hydrochloride. During the 21-day treatment period, animals in all groups underwent assessments (open field test, forced swimming test, and sucrose consumption) for depression-like behavior. At the conclusion of the treatment period, animals in all study groups were euthanized and various proteins in the prefrontal lobes were measured.

RESULTS

Depression-like behavior in rats was attenuated by AUDA. In the prefrontal lobes of PPD rats, levels of 5-LOX, COX-2, sEH, IL-1β, IL- 6, p65, p-p65, P-IκBα, NF-κB p65, and GFAP were increased while levels of epoxyeicosatrienoic acids and 5-HT were decreased. AUDA reversed these changes, thus having a similar effect as the classic antidepressant paroxetine hydrochloride.

CONCLUSION

AUDA may constrain AA/NF-κB in the prefrontal cortex of PPD rats, thus inhibiting the inflammatory response and ultimately attenuating postpartum depression-like behavior.

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).

Inhibitory Activity of Natural cis-Khellactone on Soluble Epoxide Hydrolase and Proinflammatory Cytokine Production in Lipopolysaccharides-Stimulated RAW264.7 Cells

The pursuit of anti-inflammatory agents has led to intensive research on the inhibition of soluble epoxide hydrolase (sEH) and cytokine production using medicinal plants. In this study, we evaluated the efficacy of cis-khellactone, a compound isolated for the first time from the roots of Peucedanum japonicum. The compound was found to be a competitive inhibitor of sEH, exhibiting an IC50 value of 3.1 ± 2.5 µM and ki value of 3.5 µM. Molecular docking and dynamics simulations illustrated the binding pose of (-)cis-khellactone within the active site of sEH. The results suggest that binding of the inhibitor to the enzyme is largely dependent on the Trp336-Gln384 loop within the active site. Further, cis-khellactone was found to inhibit pro-inflammatory cytokines, including NO, iNOS, IL-1β, and IL-4. These findings affirm that cis-khellactone could serve as a natural therapeutic candidate for the treatment of inflammation.

New Sight: Enzymes as Targets for Drug Development

In the dynamic realm of medical research, a resounding chord is struck by recent studies that have propelled drug discovery to new horizons across a spectrum of disciplines [...].

Genetic deletion or pharmacological inhibition of soluble epoxide hydrolase attenuated particulate matter 2.5 exposure mediated lung injury

Air pollution represented by particulate matter 2.5 (PM2.5) is closely related to diseases of the respiratory system. Although the understanding of its mechanism is limited, pulmonary inflammation is closely correlated with PM2.5-mediated lung injury. Soluble epoxide hydrolase (sEH) and epoxy fatty acids play a vital role in the inflammation. Herein, we attempted to use the metabolomics of oxidized lipids for analyzing the relationship of oxylipins with lung injury in a PM2.5-mediated mouse model, and found that the cytochrome P450 oxidases/sEH mediated metabolic pathway was involved in lung injury. Furthermore, the sEH overexpression was revealed in lung injury mice. Interestingly, sEH genetic deletion or the selective sEH inhibitor TPPU increased levels of epoxyeicosatrienoic acids (EETs) in lung injury mice, and inactivated pulmonary macrophages based on the MAPK/NF-κB pathway, resulting in protection against PM2.5-mediated lung injury. Additionally, a natural sEH inhibitor luteolin from Inula japonica displayed a pulmonary protective effect towards lung injury mediated by PM2.5 as well. Our results are consistent with the sEH message and protein being both a marker and mechanism for PM2.5-induced inflammation, which suggest its potential as a pharmaceutical target for treating diseases of the respiratory system.

Inhibitory activity of lignanamides isolated from hemp seed hulls(Cannabis sativa L.) against soluble epoxide hydrolase

Soluble epoxide hydrolase (sEH) is a therapeutic target for inflammation. In the present study, we isolated one new (1) and four known (2-5) compounds from the ethyl acetate fraction of hemp seed hulls. Their structures were elucidated as lignanamides via nuclear magnetic resonance and mass spectral analyses. All five compounds inhibited sEH activity, with half-maximal inhibitory concentrations of 2.7 ± 0.3 to 18.3 ± 1.0 μM. These lignanamides showed a competitive mechanism of inhibition via binding to sEH, with ki values below 10 μmol. Molecular simulations revealed that compounds 1-5 fit stably into the active site of sEH, and the key amino acid residues participating in their bonds were identified. It was confirmed that the potential inhibitors 4 and 5 continuously maintained a distance of 3.5 Å from one (Tyr383) and four amino (Asp335, Tyr383, Asn472, tyr516) residues, respectively. These findings provide a framework for the development of naturally derived sEH inhibitors.

Quantification of soluble epoxide hydrolase inhibitors in experimental and clinical samples using the nanobody-based ELISA

To ensure proper dosage of a drug, analytical quantification of it in biofluid is necessary. Liquid chromatography mass spectrometry (LC-MS) is the conventional method of choice as it permits accurate identification and quantification. However, it requires expensive instrumentation and is not appropriate for bedside use. Using soluble epoxide hydrolase (sEH) inhibitors (EC5026 and TPPU) as examples, we report development of a nanobody-based enzyme-linked immunosorbent assay (ELISA) for such small molecules and its use to accurately quantify the drug chemicals in human samples. Under optimized conditions, two nanobody-based ELISAs were successfully established for EC5026 and TPPU with low limits of detection of 0.085 ng/mL and 0.31 ng/mL, respectively, and two order of magnitude linear ranges with high precision and accuracy. The assay was designed to detect parent and two biologically active metabolites in the investigation of a new drug candidate EC5026. In addition, the ELISAs displayed excellent correlation with LC-MS analysis and evaluation of inhibitory potency. The results indicate that nanobody-based ELISA methods can efficiently analyze drug like compounds. These methods could be easily implemented by the bedside, in the field in remote areas or in veterinary practice. This work illustrates that nanobody based assays offer alternative and supplementary analytical tools to mass spectrometry for monitoring small molecule medicines during clinical development and therapy. Attributes of nanobody based pharmaceutical assays are discussed.

Soluble epoxide hydrolase maintains steady-state lipid turnover linked with autocrine signaling in peritoneal macrophages

Soluble epoxide hydrolase is a widely distributed bifunctional enzyme that contains N-terminal phosphatase (N-phos) and C-terminal epoxide hydrolase (C-EH) domains. C-EH hydrolyzes anti-inflammatory epoxy-fatty acids to corresponding diols and contributes to various inflammatory conditions. However, N-phos has been poorly examined. In peritoneal macrophages, the N-phos inhibitor amino-hydroxybenzoic acid (AHBA) seemed to primarily interrupt the dephosphorylation of lysophosphatidates and broadly attenuated inflammation-related functions. AHBA activated intrinsic lysophosphatidate and thromboxane A2 receptors by altering lipid-metabolite distribution; downstream the signaling, phospholipase C was facilitated to dampen intracellular Ca2+ stores and AKT kinase (protein kinase B) was activated to presumably inhibit inflammatory gene expression. Our data suggest that N-phos maintains steady-state phospholipid turnover connecting autocrine signaling and is a prospective target for controlling inflammatory responses in macrophages.

IκB kinase β (IKKβ): Structure, transduction mechanism, biological function, and discovery of its inhibitors

The effective approach to discover innovative drugs will ask natural products for answers because of their complex and changeable structures and multiple biological activities. Inhibitory kappa B kinase beta (IKKβ), known as IKK2, is a key regulatory kinase responsible for the activation of NF-κB through its phosphorylation at Ser177 and Ser181 to promote the phosphorylation of inhibitors of kappa B (IκBs), triggering their ubiquitination and degradation to active the nuclear factor kappa-B (NF-κB) cascade. Chemical inhibition of IKKβ or its genetic knockout has become an effective method to block NF-κB-mediated proliferation and migration of tumor cells and inflammatory response. In this review, we summarized the structural feature and transduction mechanism of IKKβ and the discovery of inhibitors from natural resources (e.g. sesquiterpenoids, diterpenoids, triterpenoids, flavonoids, and alkaloids) and chemical synthesis (e.g. pyrimidines, pyridines, pyrazines, quinoxalines, thiophenes, and thiazolidines). In addition, the biosynthetic pathway of novel natural IKKβ inhibitors and their biological potentials were discussed. This review will provide inspiration for the structural modification of IKKβ inhibitors based on the skeleton of natural products or chemical synthesis and further phytochemistry investigations.

Evaluation of Antibacterial Activity of Thiourea Derivative TD4 against Methicillin-Resistant Staphylococcus aureus via Destroying the NAD+/NADH Homeostasis

To develop effective agents to combat bacterial infections, a series of thiourea derivatives (TDs) were prepared and their antibacterial activities were evaluated. Our results showed that TD4 exerted the most potent antibacterial activity against a number of Staphylococcus aureus (S. aureus), including the methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis and Enterococcus faecalis strains, with the minimum inhibitory concentration (MIC) at 2-16 µg/mL. It inhibited the MRSA growth curve in a dose-dependent manner and reduced the colony formation unit in 4× MIC within 4 h. Under the transmission electron microscope, TD4 disrupted the integrity of MRSA cell wall. Additionally, it reduced the infective lesion size and the bacterial number in the MRSA-induced infection tissue of mice and possessed a good drug likeness according to the Lipinski rules. Our results indicate that TD4 is a potential lead compound for the development of novel antibacterial agent against the MRSA infection.

Macrophage Inactivation by Small Molecule Wedelolactone via Targeting sEH for the Treatment of LPS-Induced Acute Lung Injury

Soluble epoxide hydrolase (sEH) plays a critical role in inflammation by modulating levels of epoxyeicosatrienoic acids (EETs) and other epoxy fatty acids (EpFAs). Here, we investigate the possible role of sEH in lipopolysaccharide (LPS)-mediated macrophage activation and acute lung injury (ALI). In this study, we found that a small molecule, wedelolactone (WED), targeted sEH and led to macrophage inactivation. Through the molecular interaction with amino acids Phe362 and Gln384, WED suppressed sEH activity to enhance levels of EETs, thus attenuating inflammation and oxidative stress by regulating glycogen synthase kinase 3beta (GSK3β)-mediated nuclear factor-kappa B (NF-κB) and nuclear factor E2-related factor 2 (Nrf2) pathways in vitro. In an LPS-stimulated ALI animal model, pharmacological sEH inhibition by WED or sEH knockout (KO) alleviated pulmonary damage, such as the increase in the alveolar wall thickness and collapse. Additionally, WED or sEH genetic KO both suppressed macrophage activation and attenuated inflammation and oxidative stress in vivo. These findings provided the broader prospects for ALI treatment by targeting sEH to alleviate inflammation and oxidative stress and suggested WED as a natural lead candidate for the development of novel synthetic sEH inhibitors.

Inhibition effect of 1-acetoxy-6α-(2-methylbutyryl)eriolanolide toward soluble epoxide hydrolase: Multispectral analysis, molecular dynamics simulation, biochemical, and in vitro cell-based studies

Soluble epoxide hydrolase (sEH) serves as a potential target in inflammation-related diseases. Based on the bioactivity-guided separation, a new sesquiterpenoid inulajaponoid A (1) was isolated from Inula japonica with a sEH inhibitory effect, together with five known compounds, such as 1-O-acetyl-6-O-isobutyrylbritannilactone (2), 6β-hydroxytomentosin (3), 1β,8β-dihydroxyeudesma-4(15),11(13)-dien-12,6α-olide (4), (4S,6S,7S,8R)-1-O-acetyl-6-O-(3-methylvaleryloxy)-britannilactone (5), and 1-acetoxy-6α-(2-methylbutyryl)eriolanolide (6). Among them, compounds 1 and 6 were assigned as mixed and uncompetitive inhibitors, respectively. The result of immunoprecipitation (IP)-MS demonstrated the specific binding of compound 6 to sEH in the complex system, which was further confirmed by the fluorescence-based binding assay showing its equilibrium dissociation constant (K_d = 2.43 μM). The detail molecular stimulation revealed the mechanism of action of compound 6 with sEH through the hydrogen bond of amino acid residue Gln384. Furthermore, this natural sEH inhibitor (6) could suppress the MAPK/NF-κB activation to regulate inflammatory mediators, such as NO, TNF-α, and IL-6, which confirmed the anti-inflammatory effect of inhibition of sEH by 6. These findings provided a useful insight to develop sEH inhibitors upon the sesquiterpenoids.

Increased Soluble Epoxide Hydrolase Activity Positively Correlates with Mortality in Heart Failure Patients with Preserved Ejection Fraction: Evidence from Metabolomics

Epoxyeicosatrienoic acids (EETs) have pleiotropic endogenous cardiovascular protective effects and can be hydrolyzed to the corresponding dihydroxyeicosatrienoic acids by soluble epoxide hydrolase (sEH). Heart failure with preserved ejection fraction (HFpEF) has shown an increased prevalence and worse prognosis over the decades. However, the role of sEH activity in HFpEF remains unclear. We enrolled 500 patients with HFpEF and 500 healthy controls between February 2010 and March 2016. Eight types of sEH-related eicosanoids were measured according to target metabolomics, and their correlation with clinical endpoints was also analyzed. The primary endpoint was cardiac mortality, and the secondary endpoint was a composite of cardiac events, including heart failure (HF) readmission, cardiogenic hospitalization, and all-cause mortality. Furthermore, the effect of sEH inhibitors on cardiac diastolic function in HFpEF was investigated in vivo and in vitro. Patients with HFpEF showed significantly enhanced EET degradation by the sEH enzyme compared with healthy controls. More importantly, sEH activity was positively correlated with cardiac mortality in patients with HFpEF, especially in older patients with arrhythmia. A consistent result was obtained in the multiple adjusted models. Decreased sEH activity by the sEH inhibitor showed a significant effective effect on the improvement of cardiac diastolic function by ameliorating lipid disorders in cardiomyocytes of HFpEF mouse model. This study demonstrated that increased sEH activity was associated with cardiac mortality in patients with HFpEF and suggested that sEH inhibition could be a promising therapeutic strategy to improve diastolic cardiac function. Clinical trial identifier: NCT03461107 (https://clinicaltrials.gov).

Supplementary Information

The online version contains supplementary material available at 10.1007/s43657-022-00069-8.

Benzoxazolone-5-Urea Derivatives as Human Soluble Epoxide Hydrolase (sEH) Inhibitors

Inhibition of soluble epoxide hydrolase (sEH) is indicated as a new therapeutic modality against a variety of inflammatory diseases, including metabolic, renal, and cardiovascular disorders. In our ongoing research on sEH inhibitors, we synthesized novel benzoxazolone-5-urea analogues with highly potent sEH inhibitory properties inspired by the crystallographic fragment scaffolds incorporating a single H-bond donor/acceptor pair. The tractable SAR results indicated that the aryl or benzyl fragments flanking the benzoxazolone-urea scaffold conferred potent sEH inhibition, and compounds 31-39 inhibited the sEH activity with IC₅₀ values in the range of 0.39-570 nM. Docking studies and molecular dynamics simulations with the most potent analogue 33 provided valuable insights into potential binding interactions of the inhibitor in the sEH binding region. In conclusion, benzoxazolone-5-ureas furnished with benzyl groups on the urea function can be regarded as novel lead structures, which allow the development of advanced analogues with enhanced properties against sEH.

Direct targeting of sEH with alisol B alleviated the apoptosis, inflammation, and oxidative stress in cisplatin-induced acute kidney injury

Acute kidney injury (AKI) is a pathological condition characterized by a rapid decrease in glomerular filtration rate and nitrogenous waste accumulation during hemodynamic regulation. Alisol B, from Alisma orientale, displays anti-tumor, anti-complement, and anti-inflammatory effects. However, its effect and action mechanism on AKI is still unclear. Herein, alisol B significantly attenuated cisplatin (Cis)-induced renal tubular apoptosis through decreasing expressions levels of cleaved-caspase 3 and cleaved-PARP and the ratio of Bax/Bcl-2 depended on the p53 pathway. Alisol B also alleviated Cis-induced inflammatory response (e.g. the increase of ICAM-1, MCP-1, COX-2, iNOS, IL-6, and TNF-α) and oxidative stress (e.g. the decrease of SOD and GSH, the decrease of HO-1, GCLC, GCLM, and NQO-1) through the NF-κB and Nrf2 pathways. In a target fishing experiment, alisol B bound to soluble epoxide hydrolase (sEH) as a direct cellular target through the hydrogen bond with Gln384, which was further supported by inhibition kinetics and surface plasmon resonance (equilibrium dissociation constant, K _D = 1.32 μM). Notably, alisol B enhanced levels of epoxyeicosatrienoic acids and decreased levels of dihydroxyeicosatrienoic acids, indicating that alisol B reduced the sEH activity in vivo. In addition, sEH genetic deletion alleviated Cis-induced AKI and abolished the protective effect of alisol B in Cis-induced AKI as well. These findings indicated that alisol B targeted sEH to alleviate Cis-induced AKI via GSK3β-mediated p53, NF-κB, and Nrf2 signaling pathways and could be used as a potential therapeutic agent in the treatment of AKI.

Total flavonoids of Inula japonica alleviated the inflammatory response and oxidative stress in LPS-induced acute lung injury via inhibiting the sEH activity: Insights from lipid metabolomics

BACKGROUND

Acute lung injury (ALI) is a severe respiratory disease characterized by diffuse lung interstitial and respiratory distress and pulmonary edema with a mortality rate of 35%-40%. Inula japonica Thunb., known as "Xuan Fu Hua" in Chinese, is a traditional Chinese medicine Inulae Flos to use for relieving cough, eliminating expectorant, and preventing bacterial infections in the clinic, and possesses an anti-pulmonary fibrosis effect. However, the effect and action mechanism of I. japonica on ALI is still unclear.

PURPOSE

This study aimed to investigate the protective effect and underlying mechanism of total flavonoids of I. japonica (TFIJ) in the treatment of ALI.

STUDY DESIGN AND METHODS

A mouse ALI model was established through administration of LPS by the intratracheal instillation. Protective effects of TFIJ in the inflammation and oxidative stress were studied in LPS-induced ALI mice based on inflammatory and oxidative stress factors, including MDA, MPO, SOD, and TNF-α. Lipid metabolomics, bioinformatics, Western blot, quantitative real-time PCR, and immunohistochemistry were performed to reveal the potential mechanism of TFIJ in the treatment of ALI.

RESULTS

TFIJ significantly alleviated the interstitial infiltration of inflammatory cells and the collapse of the alveoli in LPS-induced ALI mice. Lipid metabolomics demonstrated that TFIJ could significantly affect the CYP2J/sEH-mediated arachidonic acid metabolism, such as 11,12-EET, 14,15-EET, 8,9-DHET, 11,12-DHET, and 14,15-DHET, revealing that sEH was the potential target of TFIJ, which was further supported by the recombinant sEH-mediated the substrate hydrolysis in vitro (IC₅₀ = 1.18 μg/ml). Inhibition of sEH by TFIJ alleviated the inflammatory response and oxidative stress via the MAPK, NF-κB, and Nrf2 signaling pathways.

CONCLUSION

These results demonstrated that TFIJ could suppress the sEH activity to stabilize the level of EETs, allowing the alleviation of the pathological course of lung injury in LPS-treated mice, which suggested that TFIJ could serve as the potential agents in the treatment of ALI.

Screening and Identification of Novel Soluble Epoxide Hydrolase Inhibitors from Corn Gluten Peptides

The objective of this study was to investigate the soluble epoxide hydrolase (sEH) inhibitory properties of corn gluten peptides. In total, 400 dipeptides and 8000 tripeptides were first virtually screened by molecular docking and 30 potential sEH inhibitory peptides were selected. Among them, WEY, WWY, WYW, YFW, and YFY showed the highest sEH inhibitory activities with IC₅₀ values of 55.41 ± 1.55, 68.80 ± 7.72, 70.66 ± 9.90, 96.00 ± 7.5, and 94.06 ± 12.86 μM, respectively. These five peptides all behaved as mixed-type inhibitors and were predicted to form hydrogen bond interactions mainly with Asp333, a key residue located in the catalytic active site of sEH. Moreover, it was found that the corn gluten hydrolysates of Alcalase, Flavourzyme, pepsin and pancreatin all exhibited high sEH inhibitory activities, with IC₅₀ values of 1.07 ± 0.08, 1.19 ± 0.24, and 1.46 ± 0.31 mg/mL, respectively. In addition, the sEH inhibitory peptides WYW, YFW, and YFY were successfully identified from the corn gluten hydrolysates by Alcalase using nano-LC-MS/MS. This study demonstrated the sEH inhibitory capacity of peptides for the first time and corn gluten might be a promising food protein source for discovering novel natural sEH inhibitory peptides.

The 1,2,3-triazole 'all-in-one' ring system in drug discovery: a good bioisostere, a good pharmacophore, a good linker, and a versatile synthetic tool

INTRODUCTION

The 1,2,3-triazole ring occupies an important space in medicinal chemistry due to its unique structural properties, synthetic versatility and pharmacological potential making it a critical scaffold. Since it is readily available through click chemistry for creating compound collections against various diseases, it has become an emerging area of interest for medicinal chemists.

AREAS COVERED

This review article addresses the unique properties of the1,2,3-triazole nucleus as an intriguing ring system in drug discovery while focusing on the most recent medicinal chemistry strategies exploited for the design and development of 1,2,3-triazole analogs as inhibitors of various biological targets.

EXPERT OPINION

Evidently, the 1,2,3-triazole ring with unique structural features has enormous potential in drug design against various diseases as a pharmacophore, a bioisoster or a structural platform. The most recent evidence indicates that it may be more emerging in drug molecules in near future along with an increasing understanding of its prominent roles in drug structures. The synthetic feasibility and versatility of triazole chemistry make it certainly ideal for creating compound libraries for more constructive structure-activity relationship studies. However, more comparative and target-specific studies are needed to gain a deeper understanding of the roles of the 1,2,3-triazole ring in molecular recognition.[Figure: see text].

Synthesis, In Vitro Profiling, and In Vivo Evaluation of Benzohomoadamantane-Based Ureas for Visceral Pain: A New Indication for Soluble Epoxide Hydrolase Inhibitors

The soluble epoxide hydrolase (sEH) has been suggested as a pharmacological target for the treatment of several diseases, including pain-related disorders. Herein, we report further medicinal chemistry around new benzohomoadamantane-based sEH inhibitors (sEHI) in order to improve the drug metabolism and pharmacokinetics properties of a previous hit. After an extensive in vitro screening cascade, molecular modeling, and in vivo pharmacokinetics studies, two candidates were evaluated in vivo in a murine model of capsaicin-induced allodynia. The two compounds showed an anti-allodynic effect in a dose-dependent manner. Moreover, the most potent compound presented robust analgesic efficacy in the cyclophosphamide-induced murine model of cystitis, a well-established model of visceral pain. Overall, these results suggest painful bladder syndrome as a new possible indication for sEHI, opening a new range of applications for them in the visceral pain field.

Quinazoline-4(3H)-one-7-carboxamide Derivatives as Human Soluble Epoxide Hydrolase Inhibitors with Developable 5-Lipoxygenase Activating Protein Inhibition

Soluble epoxide hydrolase (sEH) metabolizes epoxyeicosatrienoic acids (EETs), which are endowed with beneficial biological activities as they reduce inflammation, regulate endothelial tone, improve mitochondrial function, and decrease oxidative stress. Therefore, inhibition of sEH for maintaining high EET levels is implicated as a new therapeutic modality with broad clinical applications for metabolic, renal, and cardiovascular disorders. In our search for new sEH inhibitors, we designed and synthesized novel amide analogues of the quinazolinone-7-carboxylic acid derivative 5, a previously discovered 5-lipoxygenase-activating protein (FLAP) inhibitor, to evaluate their potential for inhibiting sEH. As a result, we identified new quinazolinone-7-carboxamides that demonstrated selective sEH inhibition with decreased FLAP inhibitor properties. The tractable SAR results indicated that the amide and thiobenzyl fragments flanking the quinazolinone nucleus are critical features governing the potent sEH inhibition, and compounds 34, 35, 37, and 43 inhibited the sEH activity with IC₅₀ values of 0.30-0.66 μM. Compound 34 also inhibited the FLAP-mediated leukotriene biosynthesis (IC₅₀ = 2.91 μM). In conclusion, quinazolinone-7-carboxamides can be regarded as novel lead structures, and newer analogues with improved efficiency against sEH along with or without FLAP inhibition can be generated.

Inhibitory Activity of Quaternary Isoquinoline Alkaloids on Soluble Epoxide Hydrolase

The quaternary isoquinoline alkaloids of palmatine (1), berberine (2), and jatrorrhizine (3) were evaluated in terms of their ability to inhibit soluble epoxide hydrolase (sEH). They had similar inhibitory activities, with IC₅₀ values of 29.6 ± 0.5, 33.4 ± 0.8, and 27.3 ± 0.4 μM, respectively. Their respective Ki values of 26.9, 46.8, and 44.5 μM—determined by enzyme kinetics—indicated that they inhibited the catalytic reaction by binding noncompetitively with sEH. The application of computational chemistry to the in vitro results revealed the site of the receptor to which the ligand would likely bind. Accordingly, three alkaloids were identified as having a suitable basic skeleton for lead compound development of sEH inhibitors.

Inhibitors of soluble epoxide hydrolase on acute lung injury: a meta-analysis of preclinical studies

INTRODUCTION

This study investigated the effects of soluble epoxide hydrolase (sEH) inhibitors on acute lung injury (ALI) using the measure of meta-analysis.

METHODS

Relative publications were systematic reviewed and retrieved by searching electronic databases including the Cochrane Library, PubMed, China National Knowledge Infrastructure, Wanfang Data, and Google Scholar.

RESULTS

Seven animal studies were included in this meta-analysis. Our result showed that the lung injury scores (SMD = - 2.31, 95% CI - 3.50 to - 1.12) and lung wet to dry weight ratios (WMD-1.44, 95% CI - 1.69 to - 1.18) were reduced in sEH inhibitors-treated animals compared with control. The mortality was improved by sEH inhibitors at 48 h (RR = 0.62, 95% CI 0.42 to 0.92), 72 h, and 120 h, but not at 24 h (RR = 0.59, 95% CI 0.35 to 1.01) and 96 h, after induction of ALI model.

CONCLUSIONS

The sEH inhibitor is a potent candidate of pharmacological agents for ALI/acute respiratory distress syndrome, as its effects on improvement of lung injury and mortality in preclinical researches.

A Review of Oxylipins in Alzheimer's Disease and Related Dementias (ADRD): Potential Therapeutic Targets for the Modulation of Vascular Tone and Inflammation

There is now a convincing body of evidence from observational studies that the majority of modifiable Alzheimer's disease and related dementia (ADRD) risk factors are vascular in nature. In addition, the co-existence of cerebrovascular disease with AD is more common than AD alone, and conditions resulting in brain ischemia likely promote detrimental effects of AD pathology. Oxylipins are a class of bioactive lipid mediators derived from the oxidation of long-chain polyunsaturated fatty acids (PUFAs) which act as modulators of both vascular tone and inflammation. In vascular cognitive impairment (VCI), there is emerging evidence that oxylipins may have both protective and detrimental effects on brain structure, cognitive performance, and disease progression. In this review, we focus on oxylipin relationships with vascular and inflammatory risk factors in human studies and animal models pertinent to ADRD. In addition, we discuss future research directions with the potential to impact the trajectory of ADRD risk and disease progression.

Synthesis and biological evaluation of new series of benzamide derivatives containing urea moiety as sEH inhibitors

The pharmacological inhibition of soluble epoxide hydrolase (sEH) was shown to reduce inflammation and pain. Herein, we described a series of newly synthesized sEH inhibitors with the trident-shaped skeleton. Intensive structural modifications led to the identification of compound B15 as a potent sEH inhibitor with an IC₅₀ value of 0.03 ± 0.01 nM. Furthermore, compound B15 showed satisfactory metabolic stability in human liver microsomes with a half-time of 197 min. In carrageenan-induced inflammatory pain rat model, compound B15 exhibited a better therapeutic effect compared to t-AUCB and Celecoxib, which demonstrated the proof of potential as anti-inflammatory agents for pain relief.

A Combined Chronic Low-Dose Soluble Epoxide Hydrolase and Acetylcholinesterase Pharmacological Inhibition Promotes Memory Reinstatement in Alzheimer’s Disease Mice Models

Alzheimer’s disease (AD) is a progressive neurological disorder with multifactorial and heterogeneous causes. AD involves several etiopathogenic mechanisms such as aberrant protein accumulation, neurotransmitter deficits, synaptic dysfunction and neuroinflammation, which lead to cognitive decline. Unfortunately, the currently available anti-AD drugs only alleviate the symptoms temporarily and provide a limited therapeutic effect. Thus, new therapeutic strategies, including multitarget approaches, are urgently needed. It has been demonstrated that a co-treatment of acetylcholinesterase (AChE) inhibitor with other neuroprotective agents has beneficial effects on cognition. Here, we have assessed the neuroprotective effects of chronic dual treatment with a soluble epoxide hydrolase (sEH) inhibitor (TPPU) and an AChE inhibitor (6-chlorotacrine or rivastigmine) in in vivo studies. Interestingly, we have found beneficial effects after chronic low-dose co-treatment with TPPU and 6-chlorotacrine in the senescence-accelerated mouse prone 8 (SAMP8) mouse model as well as with TPPU and rivastigmine co-treatment in the 5XFAD mouse model, in comparison with the corresponding monotherapy treatments. In the SAMP8 model, no substantial improvements in synaptic plasticity markers were found, but the co-treatment of TPPU and 6-chlorotacrine led to a significantly reduced gene expression of neuroinflammatory markers, such as interleukin 6 (Il-6), triggering receptor expressed on myeloid cell 2 (Trem2) and glial fibrillary acidic protein (Gfap). In 5XFAD mice, chronic low-dose co-treatment of TPPU and rivastigmine led to enhanced protein levels of synaptic plasticity markers, such as the phospho-cAMP response element-binding protein (p-CREB) ratio, brain-derived neurotrophic factor (BDNF) and postsynaptic density protein 95 (PSD95), and also to a reduction in neuroinflammatory gene expression. Collectively, these results support the neuroprotectant role of chronic low-dose co-treatment strategy with sEH and AChE inhibitors in AD mouse models, opening new avenues for effective AD treatment.

Soluble Epoxide Hydrolase as a Therapeutic Target for Neuropsychiatric Disorders

It has been found that soluble epoxide hydrolase (sEH; encoded by the EPHX2 gene) in the metabolism of polyunsaturated fatty acids (PUFAs) plays a key role in inflammation, which, in turn, plays a part in the pathogenesis of neuropsychiatric disorders. Meanwhile, epoxy fatty acids such as epoxyeicosatrienoic acids (EETs), epoxyeicosatetraenoic acids (EEQs), and epoxyeicosapentaenoic acids (EDPs) have been found to exert neuroprotective effects in animal models of neuropsychiatric disorders through potent anti-inflammatory actions. Soluble expoxide hydrolase, an enzyme present in all living organisms, metabolizes epoxy fatty acids into the corresponding dihydroxy fatty acids, which are less active than the precursors. In this regard, preclinical findings using sEH inhibitors or Ephx2 knock-out (KO) mice have indicated that the inhibition or deficiency of sEH can have beneficial effects in several models of neuropsychiatric disorders. Thus, this review discusses the current findings of the role of sEH in neuropsychiatric disorders, including depression, autism spectrum disorder (ASD), schizophrenia, Parkinson’s disease (PD), and stroke, as well as the potential mechanisms underlying the therapeutic effects of sEH inhibitors.

Allosteric regulation of the soluble epoxide hydrolase by nitro fatty acids using a combined experimental and computational approach

The human soluble epoxide hydrolase (hsEH) is a key regulator of epoxy fatty acid (EpFA) metabolism. Inhibition of sEH can maintain endogenous levels of beneficial EpFAs and reduce the levels of their corresponding diol products, thus ameliorating a variety of pathological conditions including cardiovascular, central nervous system and metabolic diseases. The quest for orthosteric drugs that bind directly to the catalytic crevice of hsEH has been prolonged and sustained over the past decades, but the disappointing outcome of clinical trials to date warrants alternative pharmacological approaches. Previously, we have shown that hsEH can be allosterically inhibited by the endogenous electrophilic lipid 15-deoxy-Δ^12,14-Prostaglandin-J₂, via covalent adduction to two cysteines, C423 and C522. In this study, we explore the properties and behaviour of three electrophilic lipids belonging to the class of the nitro fatty acids, namely 9- and 10-nitrooleate and 10-nitrolinoleate. Biochemical and biophysical investigations revealed that, in addition to C423 and C522, nitro fatty acids can covalently bind to additional nucleophilic residues in hsEH C-terminal domain (CTD), two of which predicted in this study to be latent allosteric sites. Systematic mapping of the protein mutational space and evaluation of possible propagation pathways delineated selected residues, both in the allosteric patches and in other regions of the enzyme, envisaged to play a role on allosteric signalling. The responses elicited by the ligands on the covalent adduction sites supports future fragment-based design studies of new allosteric effectors for hsEH with increased efficacy and selectivity.

Soluble epoxide hydrolase inhibitors: an overview and patent review from the last decade

INTRODUCTION

Biological effects mediated by the CYP450 arm of arachidonate cascade implicate the enzyme-soluble epoxide hydrolase (sEH) in hydrolyzing anti-inflammatory epoxy fatty acids to pro-inflammatory diols. Hence, inhibiting the sEH offers a therapeutic approach to treating inflammatory diseases. Over three decades of work has shown the role of sEH inhibitors (sEHis) in treating various disorders in rodents and larger veterinary subjects. Novel chemical strategies to enhance the efficacy of sEHi have now appeared.

AREAS COVERED

A comprehensive review of patent literature related to soluble epoxide hydrolase inhibitors in the last decade (2010-2021) is provided.

EXPERT OPINION

Soluble epoxide hydrolase (sEH) is an important enzyme that metabolizes the bioactive epoxy fatty acids (EFAs) in the arachidonic acid signaling pathway and converts them to vicinal diols, which appear to be pro-inflammatory. Inhibition of sEH hence offers a mechanism to increase in vivo epoxyeicosanoid levels and resolve pro-inflammatory pathways in disease states. Significant efforts in the field have led to potent single target as well as multi-target inhibitors with promising in vitro and widely encompassing in vivo activities. Successful clinical translation of compounds targeting sEH inhibition will further validate the promised therapeutic potential of this pathway in treating human diseases.

Discovery and In Vivo Proof of Concept of a Highly Potent Dual Inhibitor of Soluble Epoxide Hydrolase and Acetylcholinesterase for the Treatment of Alzheimer's Disease

With innumerable clinical failures of target-specific drug candidates for multifactorial diseases, such as Alzheimer's disease (AD), which remains inefficiently treated, the advent of multitarget drug discovery has brought a new breath of hope. Here, we disclose a class of 6-chlorotacrine (huprine)-TPPU hybrids as dual inhibitors of the enzymes soluble epoxide hydrolase (sEH) and acetylcholinesterase (AChE), a multitarget profile to provide cumulative effects against neuroinflammation and memory impairment. Computational studies confirmed the gorge-wide occupancy of both enzymes, from the main site to a secondary site, including a so far non-described AChE cryptic pocket. The lead compound displayed in vitro dual nanomolar potencies, adequate brain permeability, aqueous solubility, human microsomal stability, lack of neurotoxicity, and it rescued memory, synaptic plasticity, and neuroinflammation in an AD mouse model, after low dose chronic oral administration.

Unprecedented diterpenoid dimers with soluble epoxide hydrolase inhibitory effect from Euphorbia fischeriana

Biseuphoids A (1) and B (2), two unprecedented ent-abietane-type diterpenoid dimers linked by monomeric blocks through C-17-C-12' and C-17-C-11', respectively, were isolated from Euphorbia fischeriana, along with their biogenesis related diterpenoid monomers, 17-hydroxyjolkinolide B (3), caudicifolin (4), and fischeriabietane C (5). Their structures were elucidated by extensive spectroscopy assisted by quantum chemical NMR and ECD calculations. The unusual dimeric skeletons are possibly derived from the adduct of diterpenoid monomers through Michael-like reactions. The novel dimers 1 and 2 exhibited inhibitory activities on soluble epoxide hydrolase (sEH) with IC₅₀ values of 8.17 and 5.61 μM, respectively. Molecular dynamics studies illustrated that both 1 and 2 can occupy the catalytic pocket of sEH by forming stable hydrogen bonds with the key amino acid residues including Gln384, Asn378, Pro361, Ala365, Asn366, and Asn472.

Kurarinone alleviated Parkinson's disease via stabilization of epoxyeicosatrienoic acids in animal model

To date, no cure or preventative treatment for Parkinson’s disease (PD) has yet been developed. Here, we show that kurarinone, a natural flavonoid, alleviated parkinsonism-like symptoms induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in mice. Using a proteomics approach, we identified the soluble epoxide hydrolase (sEH) as a possible target of kurarinone’s reduction of neuroinflammation. This was supported using complementary biochemical approaches, which demonstrated that kurarinone is a high nanomolar uncompetitive inhibitor of sEH. Our findings suggest that natural products could attenuate the development of PD through inhibition of sEH.

Parkinson’s disease (PD) is one of the most common neurodegenerative disorders and is characterized by loss of dopaminergic neurons in the substantia nigra (SN), causing bradykinesia and rest tremors. Although the molecular mechanism of PD is still not fully understood, neuroinflammation has a key role in the damage of dopaminergic neurons. Herein, we found that kurarinone, a unique natural product from Sophora flavescens, alleviated the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)–induced behavioral deficits and dopaminergic neurotoxicity, including the losses of neurotransmitters and tyrosine hydroxylase (TH)–positive cells (SN and striatum [STR]). Furthermore, kurarinone attenuated the MPTP-mediated neuroinflammation via suppressing the activation of microglia involved in the nuclear factor kappa B signaling pathway. The proteomics result of the solvent-induced protein precipitation and thermal proteome profiling suggest that the soluble epoxide hydrolase (sEH) enzyme, which is associated with the neuroinflammation of PD, is a promising target of kurarinone. This is supported by the increase of plasma epoxyeicosatrienoic acids (sEH substrates) and the decrease of dihydroxyeicosatrienoic acids (sEH products), and the results of in vitro inhibition kinetics, surface plasmon resonance, and cocrystallization of kurarinone with sEH revealed that this natural compound is an uncompetitive inhibitor. In addition, sEH knockout (KO) attenuated the progression of PD, and sEH KO plus kurarinone did not further reduce the protection of PD in MPTP-induced PD mice. These findings suggest that kurarinone could be a potential natural candidate for the treatment of PD, possibly through sEH inhibition.

Activating endogenous resolution pathways by soluble epoxide hydrolase inhibitors for the management of COVID-19

Anti-inflammatory, specialized proresolving mediators such as resolvins, protectins, maresins, and lipoxins derived from polyunsaturated acids may play a potential role in lung diseases as they protect different organs in animal disease models. Polyunsaturated fatty acids are an important resource for epoxy fatty acids (EET, EEQ, and EDP) that mediate a broad array of anti-inflammatory and proresolving mechanisms, such as mitigation of the cytokine storm. However, epoxy fatty acids are rapidly metabolized by soluble epoxide hydrolase (sEH). In animal studies, administration of sEH inhibitors (sEHIs) increases epoxy fatty acid levels, reduces lung inflammation, and improves lung function, making it a viable COVID-19 treatment approach. Thus, using sEHIs to activate endogenous resolution pathways might be a novel method to minimize organ damage in severe cases and improve outcomes in COVID-19 patients. This review focuses on the use of sEH inhibitors to activate endogenous resolution mechanisms for the treatment of COVID-19.

Glomerular Biomechanical Stress and Lipid Mediators during Cellular Changes Leading to Chronic Kidney Disease

Hyperfiltration is an important underlying cause of glomerular dysfunction associated with several systemic and intrinsic glomerular conditions leading to chronic kidney disease (CKD). These include obesity, diabetes, hypertension, focal segmental glomerulosclerosis (FSGS), congenital abnormalities and reduced renal mass (low nephron number). Hyperfiltration-associated biomechanical forces directly impact the cell membrane, generating tensile and fluid flow shear stresses in multiple segments of the nephron. Ongoing research suggests these biomechanical forces as the initial mediators of hyperfiltration-induced deterioration of podocyte structure and function leading to their detachment and irreplaceable loss from the glomerular filtration barrier. Membrane lipid-derived polyunsaturated fatty acids (PUFA) and their metabolites are potent transducers of biomechanical stress from the cell surface to intracellular compartments. Omega-6 and ω-3 long-chain PUFA from membrane phospholipids generate many versatile and autacoid oxylipins that modulate pro-inflammatory as well as anti-inflammatory autocrine and paracrine signaling. We advance the idea that lipid signaling molecules, related enzymes, metabolites and receptors are not just mediators of cellular stress but also potential targets for developing novel interventions. With the growing emphasis on lifestyle changes for wellness, dietary fatty acids are potential adjunct-therapeutics to minimize/treat hyperfiltration-induced progressive glomerular damage and CKD.

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.

Design, synthesis and mechanistic study of novel diarylpyrazole derivatives as anti-inflammatory agents with reduced cardiovascular side effects

Novel diarylpyrazole (5a-d, 6a-e, 12, 13, 14, 15a-c and 11a-g) derivatives were designed, synthesized and evaluated for their dual COX-2/sEH inhibitory activities via recombinant enzyme assays to explore their anti-inflammatory activities and cardiovascular safety profiles. Comprehensively, the structures of the synthesized compounds were established via spectral and elemental analyses, followed by the assessment of both their in vitro COX inhibitory and in vivo anti-inflammatory activities. The most active compounds as COX inhibitors were further evaluated for their in vitro 5-LOX and sEH inhibitory activities, alongside with their in vivo analgesic and ulcerogenic effects. Compounds 6d and 11f showed excellent inhibitory activities against both COX-2 and sEH (COX-2 IC₅₀ = 0.043 and 0.048 µM; sEH IC₅₀ = 83.58 and 83.52 μM, respectively). Moreover, the compounds demonstrated promising results as anti-inflammatory and analgesic agents with considerable ED₅₀ values and gastric safety profiles. Remarkably, the most active COX inhibitors 6d and 11f possessed improved cardiovascular safety profiles, if compared to celecoxib, as shown by the laboratory evaluation of both essential cardiac biochemical parameters (troponin-1, prostacyclin, tumor necrosis factor-α, lactate dehydrogenase, reduced glutathione and creatine kinase-M) and histopathological studies. On the other hand, docking simulations confirmed that the newly synthesized compounds displayed sufficient structural features required for binding to the target COX-2 and sEH enzymes. Also, in silico ADME studies prediction and drug-like properties of the compounds revealed favorable oral bioavailability results. Collectively, the present work could be featured as a promising future approach towards novel selective COX-2 inhibitors with declined cardiovascular risks.

Bisfischoids A and B, dimeric ent-abietane-type diterpenoids with anti-inflammatory potential from Euphorbia fischeriana Steud

Two undescribed ent-abietane-type diterpenoid dimers with nonacyclic backbone formed by intermolecular [4 + 2] cycloaddition into a spirocyclic skeleton, bisfischoids A (1) and B (2), along with a known one fischdiabietane A (3), were identified from Euphorbia fischeriana Steud. Their structures were elucidated by extensive spectroscopic analysis, ECD and NMR calculation combined with DP4+ probability analysis, as well as X-ray diffraction. The anti-inflammatory potential of dimers 1-3 were examined using their inhibitory effects on soluble epoxide hydrolase (sEH), which revealed that 1 and 2 exhibited promising activities with inhibition constant (Ki) of 3.20 and 1.95 μM, respectively. Further studies of molecular docking and molecular dynamics indicated that amino acid residue Tyr343 in the catalytic cavity of sEH was the key site for their inhibitory function.

Inhibition of soluble epoxide hydrolase by phytochemical constituents of the root bark of Ulmus davidiana var. japonica

A novel compound 1 and nine known compounds (2–10) were isolated by open column chromatography analysis of the root bark of Ulmus davidiana. Pure compounds (1–10) were tested in vitro to determine the inhibitory activity of the catalytic reaction of soluble epoxide hydrolase (sEH). Compounds 1, 2, 4, 6–8, and 10 had IC₅₀ values ranging from 11.4 ± 2.3 to 36.9 ± 2.6 μM. We used molecular docking to simulate inhibitor binding of each compound and estimated the binding pose of the catalytic site of sEH. From this analysis, the compound 2 was revealed to be a potential inhibitor of sEH in vitro and in silico. Additionally, molecular dynamics (MD) study was performed to find detailed interaction signals of inhibitor 2 with enzyme. Finally, compound 2 is promising candidates for the development of a new sEH inhibitor from natural plants.

Natural soluble epoxide hydrolase inhibitors from Inula britanica and their potential interactions with soluble epoxide hydrolase: Insight from inhibition kinetics and molecular dynamics

Soluble epoxide hydrolase (sEH) is a potential drug target to treat inflammation and neurodegenerative diseases. In this study, we found that the extract of Inula britanica exhibited significantly inhibitory effects against sEH, therefore, we investigated its phytochemical constituents to obtain seven new compounds together with sixteen known ones (1-20), including two pairs of novel enantiomers, (2S,3S)-britanicafanin A (1a), (2R,3R)-britanicafanin A (1b), (2R,3S)-britanicafanin B (2a), and (2S,3R)-britanicafanin B (2b), and three new lignans britanicafanins C-E (3-5). Their structures were determined by HRESIMS, 1D and 2D NMR, and electronic circular dichroism (ECD) spectra as well as quantum chemical computations. All the isolates were evaluated for their inhibitory effects against sEH, compounds 1-3, 5-7, 9, 10, 13, 14, and 17-20 showed significant inhibitory effects against sEH with IC₅₀ values from 3.56 μM to 26.93 μM. The inhibition kinetics results indicated that compounds 9, 10, 13, and 19 were all uncompetitive inhibitors, and their inhibition constants (K_i) values were 7.11, 1.99, 4.06, and 8.78 μM, respectively. Their potential interactions were analyzed by molecular docking and molecular dynamics (MD), which suggested that amino acid residues Asp335 and Asn359, especially Gln384, played an important role in the inhibition of compounds 10 and 13 on sEH, and compounds 10 and 13 could be considered as the potential candidates for the development of sEH inhibitors.

From the Design to the In Vivo Evaluation of Benzohomoadamantane-Derived Soluble Epoxide Hydrolase Inhibitors for the Treatment of Acute Pancreatitis

The pharmacological inhibition of soluble epoxide hydrolase (sEH) is efficient for the treatment of inflammatory and pain-related diseases. Numerous potent sEH inhibitors (sEHIs) present adamantyl or phenyl moieties, such as the clinical candidates AR9281 or EC5026. Herein, in a new series of sEHIs, these hydrophobic moieties have been merged in a benzohomoadamantane scaffold. Most of the new sEHIs have excellent inhibitory activities against sEH. Molecular dynamics simulations suggested that the addition of an aromatic ring into the adamantane scaffold produced conformational rearrangements in the enzyme to stabilize the aromatic ring of the benzohomoadamantane core. A screening cascade permitted us to select a candidate for an in vivo efficacy study in a murine model of cerulein-induced acute pancreatitis. The administration of 22 improved the health status of the animals and reduced pancreatic damage, demonstrating that the benzohomoadamantane unit is a promising scaffold for the design of novel sEHIs.