Bioisosteric Replacement of Arylamide-Linked Spine Residues with N-Acylhydrazones and Selenophenes as a Design Strategy to Novel Dibenzosuberone Derivatives as Type I 1/2 p38α MAP Kinase Inhibitors

Radical-Triggered Bicyclization and Aryl Migration of 1,7-Diynes with Diphenyl Diselenide for the Synthesis of Selenopheno[3,4-c]quinolines

The translocation of an aryl group from selenium into carbon enabled by the cleavage of the C-Se bond is reported by using nitrogen atom-linked 1,7-diynes and diaryl diselenides as starting materials, leading to various selenophene derivatives in a regioselective manner. This method enables the construction of two C-Se bonds and two C-C bonds through sequential radical bicyclization and 1,2-aryl migration under metal-free conditions. Control experiments and mechanistic studies suggest that this reaction proceeds through the cleavage of the inert C(Ph)-Se bond, facilitating the aryl translocation process. This transformation enables the one-step conversion of simple diselenides into diverse selenopheno[3,4-c]quinolines via a radical-promoted process, holding significant potential for new seleniferous heterocycles.

Function and inhibition of P38 MAP kinase signaling: Targeting multiple inflammation diseases

Inflammation is a natural host defense mechanism that protects the body from pathogenic microorganisms. A growing body of research suggests that inflammation is a key factor in triggering other diseases (lung injury, rheumatoid arthritis, etc.). However, there is no consensus on the complex mechanism of inflammatory response, which may include enzyme activation, mediator release, and tissue repair. In recent years, p38 MAPK, a member of the MAPKs family, has attracted much attention as a central target for the treatment of inflammatory diseases. However, many p38 MAPK inhibitors attempting to obtain marketing approval have failed at the clinical trial stage due to selectivity and/or toxicity issues. In this paper, we discuss the mechanism of p38 MAPK in regulating inflammatory response and its key role in major inflammatory diseases and summarize the synthetic or natural products targeting p38 MAPK to improve the inflammatory response in the last five years, which will provide ideas for the development of novel clinical anti-inflammatory drugs based on p38 MAPK inhibitors.

In Situ Inhibitor Synthesis and Screening by Fluorescence Polarization: An Efficient Approach for Accelerating Drug Discovery

Target-directed dynamic combinatorial chemistry has emerged as a useful tool for hit identification, but has not been widely used, in part due to challenges associated with analyses involving complex mixtures. We describe an operationally simple alternative: in situ inhibitor synthesis and screening (ISISS), which links high-throughput bioorthogonal synthesis with screening for target binding by fluorescence. We exemplify the ISISS method by showing how coupling screening for target binding by fluorescence polarization with the reaction of acyl-hydrazides and aldehydes led to the efficient discovery of a potent and novel acylhydrazone-based inhibitor of human prolyl hydroxylase 2 (PHD2), a target for anemia treatment, with equivalent in vivo potency to an approved medicine.

In Situ Inhibitor Synthesis and Screening by Fluorescence Polarization: An Efficient Approach for Accelerating Drug Discovery

Target-directed dynamic combinatorial chemistry has emerged as a useful tool for hit identification, but has not been widely used, in part due to challenges associated with analyses involving complex mixtures. We describe an operationally simple alternative: in situ inhibitor synthesis and screening (ISISS), which links high-throughput bioorthogonal synthesis with screening for target binding by fluorescence. We exemplify the ISISS method by showing how coupling screening for target binding by fluorescence polarization with the reaction of acyl-hydrazides and aldehydes led to the efficient discovery of a potent and novel acylhydrazone-based inhibitor of human prolyl hydroxylase 2 (PHD2), a target for anemia treatment, with equivalent in vivo potency to an approved medicine.

Decisive role of water and protein dynamics in residence time of p38α MAP kinase inhibitors

Target residence time plays a crucial role in the pharmacological activity of small molecule inhibitors. Little is known, however, about the underlying causes of inhibitor residence time at the molecular level, which complicates drug optimization processes. Here, we employ all-atom molecular dynamics simulations (~400 μs in total) to gain insight into the binding modes of two structurally similar p38α MAPK inhibitors (type I and type I½) with short and long residence times that otherwise show nearly identical inhibitory activities in the low nanomolar IC₅₀ range. Our results highlight the importance of protein conformational stability and solvent exposure, buried surface area of the ligand and binding site resolvation energy for residence time. These findings are further confirmed by simulations with a structurally diverse short residence time inhibitor SB203580. In summary, our data provide guidance in compound design when aiming for inhibitors with improved target residence time.

The molecular determinants of the residence time of a small molecule inhibitor at its target protein are not well understood. Here, Pantsar et al. show that the target protein’s conformational stability and solvent exposure are key factors governing the target residence time of kinase inhibitors.

Design, Synthesis, and Antifungal Activity of Novel Thiophene/Furan-1,3,4-Oxadiazole Carboxamides as Potent Succinate Dehydrogenase Inhibitors

Succinate dehydrogenase (SDH) is known as an ideal target for the investigations of fungicides. To develop novel SDH inhibitors, 30 novel thiophene/furan-1,3,4-oxadiazole carboxamide derivatives were designed and synthesized. In the in vitro antifungal assay, a majority of the target compounds demonstrated fair to potent antifungal activity against seven tested phytopathogenic fungi. Compounds 4b, 4g, 4h, 4i, and 5j showed remarkable antifungal activity against Sclerotinia sclerotiorum, affording EC50 values ranging from 0.1∼1.1 mg/L. In particular, compound 4i displayed the most potent activity against S. sclerotiorum (EC₅₀ = 0.140 ± 0.034 mg/L), which was superior to that of boscalid (EC₅₀ = 0.645 ± 0.023 mg/L). A further morphological investigation revealed the abnormal mycelia and damaged cell structures of compound 4i-treated S. sclerotiorum by scanning electron microscopy. Furthermore, the in vivo antifungal assay against S. sclerotiorum revealed that compounds 4g and 4i were effective for suppressing rape Sclerotinia rot at a dosage of 200 mg/L. In the SDH inhibition assay, compounds 4g and 4i also presented significant inhibitory activity with IC₅₀ values of 1.01 ± 0.21 and 4.53 ± 0.19 μM, respectively, which were superior or equivalent to that of boscalid (3.51 ± 2.02 μM). Molecular docking and molecular dynamics simulation of compound 4g with SDH revealed that compound 4g could form strong interactions with the key residues of the SDH. These results indicated that this class of derivatives could be a promising scaffold for the discovery and development of novel SDH inhibitors.

Quantitative Polypharmacology Profiling Based on a Multifingerprint Similarity Predictive Approach

We present a new quantitative ligand-based bioactivity prediction approach employing a multifingerprint similarity search algorithm, enabling the polypharmacological profiling of small molecules. Quantitative bioactivity predictions are made on the basis of the statistical distributions of multiple Tanimoto similarity θ values, calculated through 13 different molecular fingerprints, and of the variation of the measured biological activity, reported as ΔpIC₅₀, for all of the ligands sharing a given protein drug target. The application data set comprises as much as 4241 protein drug targets as well as 418 485 ligands selected from ChEMBL (release 25) by employing a set of well-defined filtering rules. Several large internal and external validation studies were carried out to demonstrate the robustness and the predictive potential of the herein proposed method. Additional comparative studies, carried out on two freely available and well-known ligand-target prediction platforms, demonstrated the reliability of our proposed approach for accurate ligand-target matching. Moreover, two applicative cases were also discussed to practically describe how to use our predictive algorithm, which is freely available as a user-friendly web platform. The user can screen single or multiple queries at a time and retrieve the output as a terse html table or as a json file including all of the information concerning the explored similarities to obtain a deeper understanding of the results. High-throughput virtual reverse screening campaigns, allowing for a given query compound the quick detection of the potential drug target from a large collection of them, can be carried out in batch on demand.

Synthesis of Novel N-Acylhydrazones and Their C-N/N-N Bond Conformational Characterization by NMR Spectroscopy

In this article, a synthesis of N’-(benzylidene)-2-(6-methyl-1H-pyrazolo[3,4-b]quinolin-1-yl)acetohydrazides and their structural interpretation by NMR experiments is described in an attempt to explain the duplication of some peaks in their ¹H- and ¹³C-NMR spectra. Twenty new 6-methyl-1H-pyrazolo[3,4-b]quinoline substituted N-acylhydrazones 6(a–t) were synthesized from 2-chloro-6-methylquinoline-3-carbaldehyde (1) in four steps. 2-Chloro-6-methylquinoline-3-carbaldehyde (1) afforded 6-methyl-1H-pyrazolo[3,4-b]quinoline (2), which upon N-alkylation yielded 2-(6-methyl-1H-pyrazolo[3,4-b]quinolin-1-yl)acetate (3). The hydrazinolysis of 3 followed by the condensation of resulting 2-(6-methyl-1H-pyrazolo[3,4-b]quinolin-1-yl)acetohydrazide (4) with aromatic aldehydes gave N-acylhydrazones 6(a–t). Structures of the synthesized compounds were established by readily available techniques such as FT-IR, NMR and mass spectral studies. The stereochemical behavior of 6(a–t) was studied in dimethyl sulfoxide-d₆ solvent by means of ¹H NMR and ¹³C NMR techniques at room temperature. NMR spectra revealed the presence of N’-(benzylidene)-2-(6-methyl-1H-pyrazolo[3,4-b]quinolin-1-yl)acetohydrazides as a mixture of two conformers, i.e., E_(C=N)(N-N) synperiplanar and E_(C=N)(N-N)antiperiplanar at room temperature in DMSO-d₆. The ratio of both conformers was also calculated and E_{(C=N) (N-N)} syn-periplanar conformer was established to be in higher percentage in equilibrium with the E_{(C=N) (N-N)}anti-periplanar form.

Selective and effective anticancer agents: Synthesis, biological evaluation and structure-activity relationships of novel carbazole derivatives

Carbazole alkaloids is an important class of natural products with diverse biological functions. So, the aim of this article is to explore new chemical entities containing carbazole scaffold as potential novel cytotoxic agents based on our developed three-component indole-to-carbazole reaction. Two series of carbazole derivatives were designed and synthesized, and their in vitro cytotoxic activities against three cell lines (A875, HepG2, and MARC145) were evaluated. The results indicated that some of these carbazole derivatives exhibited significantly good cytotoxic activities against tested cell lines compared with the control 5-fluorouracil (5-FU). Especially, carbazole acylhydrazone compounds 7g and 7p displayed high inhibitory activity on cancer cells, but almost no activity on normal cells. Further analysis of induced apoptosis for potential compounds indicated that the potential antitumor agents induced cell death in A875 cells at least partly (initially) by apoptosis, which might be used as promising lead scaffold for discovery of novel carbazole-type cytotoxic agents.