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

Repositioning of Small Molecules through the Inverse Virtual Screening in silico Tool: Case of Benzothiazole-Based Inhibitors of Soluble Epoxide Hydrolase (sEH)

Computational techniques accelerate drug discovery by identifying bioactive compounds for specific targets, optimizing molecules with moderate activity, or facilitating the repositioning of inactive items onto new targets. Among them, the Inverse Virtual Screening (IVS) approach is aimed at the evaluation of one or a small set of molecules against a panel of targets for addressing target identification. In this work, a focused library of benzothiazole-based compounds was re-investigated by IVS. Four items, originally synthesized and tested on bromodomain-containing protein 9 (BRD9) but yielding poor binding, were critically re-analyzed, disclosing only a partial fit with 3D structure-based pharmacophore models, which, in the meanwhile, were developed for this target. Afterwards, these compounds were re-evaluated through IVS on a panel of proteins involved in inflammation and cancer, identifying soluble epoxide hydrolase (sEH) as a putative interacting target. Three items were subsequently confirmed as able to interfere with sEH activity, leading to inhibition percentages spanning from 70 % up to 30 % when tested at 10 μM. Finally, one benzothiazole-based compound emerged as the most promising inhibitor featuring an IC50 in the low micromolar range (IC50=6.62±0.13 μM). Our data confirm IVS as a predictive tool for accelerating the target identification and repositioning processes.

Ureas derived from camphor and fenchone reveal enantiomeric preference of human soluble epoxide hydrolase

The soluble epoxide hydrolase (sEH) is a potential target to treat cardiovascular, renal and neuronal diseases. A series of sEH inhibitors containing naturally occurring lipophilic groups (originating from camphor and fenchone) were developed. Inhibitory potency ranging from 0.7 nM to 6.47 μM was obtained. It was discovered that ureas derived from L-camphor were more active against sEH (2.3-fold average) than the corresponding analogues derived from D-camphor indicating enantiomeric preference of sEH. Ureas derived from fenchone possess lower activity against sEH (ca. 80-fold on average) than their camphor-derived analogs due to the specific structure of the lipophilic fragment and show less enantiomeric preference (1.75-fold on average). Moreover, fenchone-derived ureas show no consistency in enantiomeric preference. Endo/exo-form of compound L-3a derived from L-camphor is 4-fold more potent than the corresponding analogue prepared from D-camphor (IC50 = 0.7 nM vs. 2.8 nM) making it the most promising sEH inhibitor among the tested series.

N-Substituted S-Alkyl Carbamothioates in the Synthesis of Nitrogen-containing Functional Derivatives of the Adamantane Series

A series of new asymmetric ureas, urethanes, and other derivatives of the framework structure have been synthesized by the reactions of adamantan-1-yl isocyanate generated in situ by the thermolysis of carbamothioates with nitrogen-containing nucleophiles and alcohols.

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.

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.

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

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

In Vitro and In Silico Insights into sEH Inhibitors with Amide-Scaffold from the Leaves of Capsicum chinense Jacq

Two compounds termed 1 and 2 were isolated from the leaves of Capsicum chinense using column chromatography. Their structures were identified as amide scaffolds by analyzing spectroscopic signals. Compounds 1 and 2 have been confirmed to be competitive soluble epoxide hydrolase (sEH) inhibitors that suppress the catalytic reaction of sEH in a dose-dependent manner in vitro. Molecular docking was used for analyzing two binding clusters of ligand and receptor. The results confirmed that the key amino acids interacting with the ligand were Asp335, Tyr383, and Gln384. On the basis of molecular dynamics, inhibitors 1 and 2 were noted to interact at a distance of 3.5 Å from Asp335, Tyr383, Leu408 and Tyr466, and Asp335, Tyr383, and Tyr466, respectively. These results highlight the potential of N-trans-coumaroyltyramine (1) and N-trans-feruloyltyramine (2) as sEH inhibitors.

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.

Synthesis of HIV-1 capsid protein assembly inhibitor (CAP-1) and its analogues based on a biomass approach

A biomass-derived platform chemical was utilized to access a demanded pharmaceutical substance with anti-HIV activity (HIV, human immunodeficiency virus) and a variety of structural analogues. Step economy in the synthesis of the drug core (single stage from cellulose) is studied including flexible variability of four structural units. The first synthesis and X-ray structure of the inhibitor of HIV-1 capsid protein assembly (CAP-1) is described.