3,5-Disubstituted quinolines as novel c-Jun N-terminal kinase inhibitors

Rabdosichuanin C inhibits productions of pro-inflammatory mediators regulated by NF-κB signaling in LPS-stimulated RAW264.7 cells

Chronic pharyngitis (CP) is an inflammatory disease of the pharyngeal mucosa and its lymphatic tissues that is difficult to treat clinically. However, research on the exact therapeutic agents and molecular mechanisms of CP is still unclear. In this study, we investigated Rabdosichuanin C (RC) to attenuate lipopolysaccharide (LPS)-induced inflammatory damage in RAW264.7 cells by a combination of targeted virtual screening and in vitro activity assay and further clarified its molecular mechanism of action centering on the IκB/nuclear factor kappa B (NF-κB) pathway. Molecular docking and pharmacophore simulation methods were used to screen compounds with IκB inhibitory effects. Expression of genes and proteins related to the IκB/NF-κB signaling pathway by RC in LPS-induced inflammatory injury model of RAW264.7 cells was detected by PCR, enzyme-linked immunosorbent assay, and Western blot. The docking of RC with IκB protein showed good binding energy, and pharmacophore simulations further confirmed the active effect of RC in inhibiting IκB protein. RC intervention in LPS-induced RAW264.7 cells significantly reduced the expression levels of inflammatory factors tumor necrosis factor-α, interleukins-6, iNOS, and CD-86 at the messenger RNA and protein levels, downregulated IκB, p65 protein phosphorylation levels, and significantly inhibited IκB/NF-κB signaling pathway activation. Virtual screening provided us with an effective method to rapidly identify compounds RC that target inhibit the action of IκB, and the activity results showed that RC inhibits NF-κB signaling pathway activation. It is suggested that RC may play a role in the treatment of CP by inhibiting the IκB/NF-κB signaling pathway.

A reactivity model for oxidative addition to palladium enables quantitative predictions for catalytic cross-coupling reactions

Making accurate, quantitative predictions of chemical reactivity based on molecular structure is an unsolved problem in chemical synthesis, particularly for complex molecules. We report an approach to reactivity prediction for...

Chemoinformatic analysis of alkaloids isolated from Peganum genus

Peganum genus is rich with its high phytochemical and botanical variability. Peganum species have been used as a sedative, antitumor, analgesic and antidepressant. This paper aims to study the molecular diversity of Peganum genus and to shed more light on the structure-activity relationship of the alkaloids isolated from Peganum genus. All Peganum alkaloids were grouped according to their structural properties. A chemoinformatic approach (SwissTargetPrediction) was used to determine the molecular targets of these alkaloids. To analyze and visualize the results, R software was used to generate hierarchical clustering heatmaps. The results of this study can help researchers to better understand the structure-activity relationship of Peganum alkaloids and how substitution can affect the biological activity of those alkaloids.

Recent Advances in c-Jun N-Terminal Kinase (JNK) Inhibitors

c-Jun N-Terminal Kinases (JNKs), members of the Mitogen-Activated Protein Kinase (MAPK) signaling pathway, play a key role in the pathogenesis of many diseases including cancer, inflammation, Parkinson's disease, Alzheimer's disease, cardiovascular disease, obesity, and diabetes. Therefore, JNKs represent new and excellent target by therapeutic agents. Many JNK inhibitors based on different molecular scaffolds have been discovered in the past decade. However, only a few of them have advanced to clinical trials. The major obstacle for the development of JNK inhibitors as therapeutic agents is the JNKisoform selectivity. In this review, we describe the recent development of JNK inhibitors, including ATP competitive and ATP non-competitive (allosteric) inhibitors, bidentatebinding inhibitors and dual inhibitors, the challenges, and the future direction of JNK inhibitors as potential therapeutic agents.

An Overview of Privileged Scaffold: Quinolines and Isoquinolines in Medicinal Chemistry as Anticancer Agents

Cancer is one of the most difficult diseases and causes of death for many decades. Many pieces of research are continuously going on to get a solution for cancer. Quinoline and isoquinoline derivatives have shown their possibilities to work as an antitumor agent in anticancer treatment. The members of this privileged scaffold quinoline and isoquinoline have shown their controlling impacts on cancer treatment through various modes. In particular, this review suggests the current scenario of quinoline and isoquinoline derivatives as antitumor agents and refine the path of these derivatives to find and develop new drugs against an evil known as cancer.

Green Synthesis, Experimental and Theoretical Studies to Discover Novel Binders of Exosomal Tetraspanin CD81 Protein

A new class of benzothiazole-appended quinoline derivatives (6-8) was synthesized via one-pot TPGS micellar-mediated acid-catalyzed nucleophilic addition, followed by aerobic oxidative cyclization of 3-formylquinoline-2-one (2), 3-formylquinoline-2-thione (3), and 2-azidoquinoline-3-carbaldehyde (4) individually with 2-amino thiophenol (5). The structures of the prepared compounds were confirmed using suitable spectroscopic methods complemented with single-crystal X-ray diffraction analysis. Time-dependent density functional theory-based optimization of molecular structures, bond lengths, bond angles, HOMO-LUMO energy gaps, and molecular electrostatic potential maps was theoretically computed at the B3LYP/6-311++g(d) level. The molecular docking studies recommended that 6-8 bound to the active site cavity of CD81 effectively with the binding energies of -6.9, -6.3, and -6.5 kcal mol^-1, respectively. Further, MD simulation studies of compound 6 suggested that the binding resulted in the stabilization of the CD81 molecule. Thus, all theoretical predictions associated with the experimental verifications motivated to discover novel approaches for cancer therapy.

C-Jun N-terminal kinase inhibitors: Structural insight into kinase-inhibitor complexes

The activation of c-Jun N-terminal kinases (JNKs) plays an important role in physiological processes including neuronal function, immune activity, and development, and thus, JNKs have been a therapeutic target for various diseases such as neurodegenerative diseases, inflammation, and cancer. Efforts to develop JNK-specific inhibitors have been ongoing for several decades. In this process, the structures of JNK in complex with various inhibitors have contributed greatly to the design of novel compounds and to the elucidation of structure-activity relationships. Almost 100 JNK structures with various compounds have been determined. Here we summarize the information gained from these structures and classify the inhibitors into several groups based on the binding mode. These groups include inhibitors in the open conformation and closed conformation of the gatekeeper residue, non-ATP site binders, peptides, covalent inhibitors, and type II kinase inhibitors. Through this work, deep insight into the interaction of inhibitors with JNKs can be gained and this will be helpful for developing novel, potent, and selective inhibitors.

Inhibitors of the Detoxifying Enzyme of the Phytoalexin Brassinin Based on Quinoline and Isoquinoline Scaffolds

The detoxification of the phytoalexin brassinin to indole-3-carboxaldehyde and S-methyl dithiocarbamate is catalyzed by brassinin oxidase (BOLm), an inducible fungal enzyme produced by the plant pathogen Leptosphaeria maculans. Twenty-six substituted quinolines and isoquinolines are synthesized and evaluated for antifungal activity against L. maculans and inhibition of BOLm. Eleven compounds that inhibit BOLm activity are reported, of which 3-ethyl-6-phenylquinoline displays the highest inhibitory effect. In general, substituted 3-phenylquinolines show significantly higher inhibitory activities than the corresponding 2-phenylquinolines. Overall, these results indicate that the quinoline scaffold is a good lead to design paldoxins (phytoalexin detoxification inhibitors) that inhibit the detoxification of brassinin by L. maculans.

JNK pathway signaling: a novel and smarter therapeutic targets for various biological diseases

JNK pathway regulates various physiological processes including inflammatory responses, cell differentiation, cell proliferation, cell death, cell survival and expression of proteins. Deregulation of JNK is linked with various diseases including neurodegenerative disease, autoimmune disease, diabetes, cancer, cardiac hypertrophy and asthma. Three distinct genes JNK1, JNK2 and JNK3 have been identified as regulator of JNK pathway. JNK1 and JNK2 have broad tissue distribution and play a potential role in insulin resistance, inflammation and cell signaling. JNK3 is predominantly found in the CNS neurons, making it an attractive target for neurodegenerative disorders. In this review, we summarize the evidence supporting JNK as a potent therapeutic target, and small molecules from various chemical classes as JNK inhibitors.

Structural basis and biological consequences for JNK2/3 isoform selective aminopyrazoles

Three JNK isoforms, JNK1, JNK2, and JNK3 have been reported and unique biological function has been ascribed to each. It is unknown if selective inhibition of these isoforms would confer therapeutic or safety benefit. To probe JNK isoform function we designed JNK2/3 inhibitors that have >30-fold selectivity over JNK1. Utilizing site-directed mutagenesis and x-ray crystallography we identified L144 in JNK3 as a key residue for selectivity. To test whether JNK2/3 selective inhibitors protect human dopaminergic neurons against neurotoxin-induced mitochondrial dysfunction, we monitored reactive oxygen species (ROS) generation and mitochondrial membrane potential (MMP). The results showed that JNK2/3 selective inhibitors protected against 6-hydroxydopamine-induced ROS generation and MMP depolarization. These results suggest that it was possible to develop JNK2/3 selective inhibitors and that residues in hydrophobic pocket I were responsible for selectivity. Moreover, the findings also suggest that inhibition of JNK2/3 likely contributed to protecting mitochondrial function and prevented ultimate cell death.

An efficient one-pot access to N-(pyridin-2-ylmethyl) substituent biphenyl-4-sulfonamides through water-promoted, palladium-catalyzed, microwave-assisted reactions

An efficient one-pot, Pd(PPh₃)₄ catalyzed, water-promoted method with excellent substrate scope and functional group compatibility for the synthesis of N-(pyridin-2-ylmethyl) biphenyl-4-sulfonamides was developed under microwave irradiation.

Inhibitors of c-Jun N-terminal kinases: an update

The c-Jun N-terminal kinases (JNKs) are serine/threonine kinases implicated in the pathogenesis of various diseases. Recent advances in the development of novel inhibitors of JNKs will be reviewed. Significant progress in the design of JNK inhibitors displaying selectivity versus other kinases has been achieved within the past 4 years. However, the development of isoform selective JNK inhibitors is still an open task.

Design and synthesis of highly potent and isoform selective JNK3 inhibitors: SAR studies on aminopyrazole derivatives

The c-jun N-terminal kinase 3 (JNK3) is expressed primarily in the brain. Numerous reports have shown that inhibition of JNK3 is a promising strategy for treatment of neurodegeneration. The optimization of aminopyrazole-based JNK3 inhibitors with improved potency, isoform selectivity, and pharmacological properties by structure–activity relationship (SAR) studies utilizing biochemical and cell-based assays, and structure-based drug design is reported. These inhibitors had high selectivity over JNK1 and p38α, minimal cytotoxicity, potent inhibition of 6-OHDA-induced mitochondrial membrane potential dissipation and ROS generation, and good drug metabolism and pharmacokinetic (DMPK) properties for iv dosing. 26n was profiled against 464 kinases and was found to be highly selective hitting only seven kinases with >80% inhibition at 10 μM. Moreover, 26n showed good solubility, good brain penetration, and good DMPK properties. Finally, the crystal structure of 26k in complex with JNK3 was solved at 1.8 Å to explore the binding mode of aminopyrazole based JNK3 inhibitors.

Synthesis and SAR of novel isoxazoles as potent c-jun N-terminal kinase (JNK) inhibitors

The design and synthesis of isoxazole 3 is described, a potent JNK inhibitor with two fold selectivity over p38. Optimization of this scaffold led to compounds 27 and 28 which showed greatly improved selectivity over p38 by maintaining the JNK3 potency of compound 3. Extensive SAR studies will be described as well as preliminary in vivo data of the two lead compounds.

Small Molecule c-jun-N-terminal Kinase (JNK) Inhibitors Protect Dopaminergic Neurons in a Model of Parkinson's Disease

There are currently no drugs to treat neurodegeneration in Parkinson's disease (PD) and all existing medications only treat symptoms, lose efficacy over time, and produce untoward side effects. In the current work, we report the first highly selective, orally bioavailable, c-jun-N-terminal kinase (JNK) inhibitor for protection of dopaminergic neurons in vitro and in vivo. At 300 nM this compound showed statistically significant protection of primary dopaminergic neurons exposed to 1-methyl-4-phenylpyridinium (MPP(+)), had pharmacokinetic properties in rodents consistent with twice daily (b.i.d.) dosing, and was orally efficacious at 30 mg/kg in a mouse 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of Parkinson's disease. Moreover, a dose-dependent target modulation of c-jun phosphorylation served as a biomarker for demonstrating on-target inhibition of JNK as the mechanism of action for this compound. Collectively these results suggest that this JNK inhibitor could be a promising therapeutic neuroprotective agent in the treatment of Parkinson's disease.

Synthesis and SAR of novel quinazolines as potent and brain-penetrant c-jun N-terminal kinase (JNK) inhibitors

Quinazoline 3 was discovered as a novel c-jun N-terminal kinase (JNK) inhibitor with good brain penetration and pharmacokinetic (PK) properties. A number of analogs which were potent both in the biochemical and cellular assays were discovered. Quinazoline 13a was found to be a potent JNK3 inhibitor (IC(50)=40 nM), with >500-fold selectivity over p38, and had good PK and brain penetration properties. With these properties, 13a is considered a potential candidate for in vivo evaluation.

Synthesis and SAR of 4-(pyrazol-3-yl)-pyridines as novel c-jun N-terminal kinase inhibitors

The design and synthesis of a novel series of c-jun N-terminal kinase (JNK) inhibitors is described. The development of the 4-(pyrazol-3-yl)-pyridine series was discovered from an earlier pyrimidine series of JNK inhibitors. Through the optimization of the scaffold 2, several potent compounds with good in vivo profiles were discovered.

Synthesis, biological evaluation, X-ray structure, and pharmacokinetics of aminopyrimidine c-jun-N-terminal kinase (JNK) inhibitors

Given the significant body of data supporting an essential role for c-jun-N-terminal kinase (JNK) in neurodegenerative disorders, we set out to develop highly selective JNK inhibitors with good cell potency and good brain penetration properties. The structure-activity relationships (SAR) around a series of aminopyrimidines were evaluated utilizing biochemical and cell-based assays to measure JNK inhibition and brain penetration in mice. Microsomal stability in three species, P450 inhibition, inhibition of generation of reactive oxygen species (ROS), and pharmacokinetics in rats were also measured. Compounds 9g, 9i, 9j, and 9l had greater than 135-fold selectivity over p38, and cell-based IC(50) values < 100 nM. Moreover, compound 9l showed an IC(50) = 0.8 nM for inhibition of ROS and had good pharmacokinetic properties in rats along with a brain-to-plasma ratio of 0.75. These results suggest that biaryl substituted aminopyrimidines represented by compound 9l may serve as the first small molecule inhibitors to test efficacy of JNK inhibitors in neurodegenerative disorders.