Synthesis, structure–activity relationship and crystallographic studies of 3-substituted indolin-2-one RET inhibitors

Synthesis biological evaluation and molecular docking of isatin hybrids as anti-cancer and anti-microbial agents

Isatin, known as 1H-indole-2,3-dione, was originally recognised as a synthetic molecule until its discovery in the fruits of the cannonball tree, Couroupita guianensis. It is naturally occurring in plants of the genus Isatis and serves as a metabolic derivative of adrenaline in humans. Isatin possesses significant pharmacological importance, and its synthetic versatility has prompted extensive interest in its derivative compounds due to their diverse biological and pharmacological properties. These derivatives represent a valuable class of heterocyclic compounds with potential applications as precursors for synthesizing numerous valuable drugs. In the pursuit of advancing our research on isatin hybrids, we investigate the utilisation of readily available hydrazonoindolin-2-one and isatin as starting materials for the synthesis of a wide range of analogues. Characterisation of the synthesized compounds was carried out through various analytical techniques. Furthermore, the obtained compounds were subjected to extensive testing to evaluate their anticancer and antimicrobial activities. Specifically, their efficacy against key proteins, namely Staphylococcus aureus protein (PDB ID: 1JIJ), Escherichia coli protein (PDB ID: 1T9U), Pseudomonas aeruginosa protein (PDB ID: 2UV0), and Acinetobacter baumannii protein (PDB ID: 4HKG), was examined through molecular docking calculations. Several molecules, such as 3, 4, 6, 16, and 19, displayed remarkable activity against the renal cancer cell line UO-31. Additionally, the results of antimicrobial activity testing revealed that compound 16 exhibited significant cytotoxicity against Candida albicans and Cryptococcus neoformans. Subsequently, ADME/T calculations were performed to gain insights into the potential effects and reactions of these molecules within human metabolism. This comprehensive study provides valuable insights into the potential pharmacological applications of isatin derivatives and underscores their significance in drug development.

Design and Synthesis of Novel Thieno[3,2-c]quinoline Compounds with Antiproliferative Activity on RET-Dependent Medullary Thyroid Cancer Cells

RET kinase gain-of-function mutations represent the main cause of the high aggressiveness and invasiveness of medullary thyroid cancer (MTC). The selective inhibition of the RET kinase is a suitable strategy for the treatment of this endocrine neoplasia. Herein, we performed an innovative ligand-based virtual screening protocol using the DRUDITonline web service, focusing on the RET kinase as a biological target. In this process, thieno[3,2-c]quinolines 6a-e and 7a-e were proposed as new potential RET inhibitors. The selected compounds were synthetized by appropriate synthetic strategies, and in vitro evaluation of antiproliferative properties conducted on the particularly aggressive MTC cell line TT(C634R) identified compounds 6a-d as promising anticancer agents, with IC50 values in the micromolar range. Further structure-based computational studies revealed a significant capability of the most active compounds to the complex RET tyrosine kinase domain. The interesting antiproliferative results supported by in silico predictions suggest that these compounds may represent a starting point for the development of a new series of small heterocyclic molecules for the treatment of MTC.

Structure-Based Identification of Natural Compounds as Potential RET-Kinase Inhibitors for Therapeutic Targeting of Neurodegenerative Diseases

BACKGROUND

Tyrosine-protein kinase receptor Ret (RET), a proto-oncogene, is considered as an attractive drug target for cancer and neurodegenerative diseases, including Alzheimer's disease (AD).

OBJECTIVE

We aimed to identify potential inhibitors of RET kinase among natural compounds present in the ZINC database.

METHODS

A multistep structure-based virtual screening approach was used to identify potential RET kinase inhibitors based on their binding affinities, docking scores, and interactions with the biologically important residues of RET kinase. To further validate the potential of these compounds as therapeutic leads, molecular dynamics (MD) simulations for 100 ns were carried out and subsequently evaluated the stability, conformational changes, and interaction mechanism of RET in-complex with the elucidated compounds.

RESULTS

Two natural compounds, ZINC02092851 and ZINC02726682, demonstrated high affinity, specificity for the ATP-binding pocket of RET and drug-likeness properties. The MD simulation outputs indicated that the binding of both compounds stabilizes the RET structure and leads to fewer conformational changes.

CONCLUSIONS

The findings suggest that ZINC02092851 and ZINC02726682 may be potential inhibitors for RET, offering valuable leads for drug development against RET-associated diseases. Our study provides a promising avenue for developing new therapeutic strategies against complex diseases, including AD. Identifying natural compounds with high affinity and specificity for RET provides a valuable starting point for developing novel drugs that could help combat these debilitating diseases.

Identification of potential biological targets of oxindole scaffolds via in silico repositioning strategies

Background: Drug repurposing is an alternative strategy to traditional drug discovery that aims at predicting new uses for already existing drugs or clinical candidates. Drug repurposing has many advantages over traditional drug development, such as reduced attrition rates, time and costs. This is especially the case considering that most drugs investigated for repurposing have already been assessed for their safety in clinical trials. Repurposing campaigns can also be designed for libraries of already synthesized molecules at different levels of biological experimentation, from null to in vitro and in vivo. Such an extension of the "repurposing" concept is expected to provide significant advantages for the identification of novel drugs, as the synthetic accessibility of the desired compounds is often one of the limiting factors in the traditional drug discovery pipeline. Methods: In this work, we performed a computational repurposing campaign on a library of previously synthesized oxindole-based compounds, in order to identify potential new targets for this versatile scaffold. To this aim, ligand-based approaches were firstly applied to evaluate the similarity degree of the investigated compound library, with respect to ligands extracted from the DrugBank, Protein Data Bank (PDB) and ChEMBL databases. In particular, the 2D fingerprint-based and 3D shape-based similarity profiles were evaluated and compared for the oxindole derivates. Results: The analyses predicted a set of potential candidate targets for repurposing, some of them emerging by consensus of different computational analyses. One of the identified targets, i.e., the vascular endothelial growth factor receptor 2 (VEGFR-2) kinase, was further investigated by means of docking calculations, followed by biological testing of one candidate. Conclusions: While the compound did not show potent inhibitory activity towards VEGFR-2, the study highlighted several other possibilities of therapeutically relevant targets that may be worth of consideration for drug repurposing.

N-([1,1'-biaryl]-4-yl)-1-naphthamide-based scaffolds synthesis, their cheminformatics analyses, and screening as bacterial biofilm inhibitor

Naphthamides have pharmacological potential as they express strong activities against microorganisms. The commercially available naphthoyl chloride and 4-bromoaniline were condensed in dry dichloromethane (DCM) in the presence of Et₃ N to form N-(4-bromophenyl)-1-naphthamide (86%) (3). Using a Pd(0) catalyzed Suzuki-Miyaura Cross-Coupling reaction of (3) and various boronic acids, a series of N-([1,1'-biaryl]-4-yl)-1-naphthamide derivatives (4a-h) were synthesized in moderate to good yields. The synthesized derivatives were evaluated for cytotoxicity haemolytic assay and biofilm inhibition activity through in silico and in vitro studies. Molecular docking, ADME (absorption, distribution, metabolism, and excretion), toxicity risk, and other cheminformatics predict synthesized molecules as biologically active moieties, further validated through in vitro studies in which compounds (4c) and (4f) showed significant haemolytic activity whereas (4e) exhibited an efficient biofilm inhibition activity against Gram-negative bacteria Escherichia coli and Gram-positive bacteria Bacillus subtilis. When forming biofilms, bacteria become resistant to various antimicrobial treatments. Currently, research is focused on the development of agents that inhibit biofilm formation, thus the present work is valuable for preventing future drug resistance.

The development of 3-substituted indolin-2-one derivatives as kinase inhibitors for cancer therapy

Kinases are pivotal regulators in tumorigenesis and metastasis by modulating the expression of oncogenes and the transcription of antioncogenes directly or indirectly. Correspondingly, multifarious 3-substituted indolin-2-one derivatives as selective kinase inhibitors for cancer therapy exhibited a low nanomolar activity with prominent efficacy, superior response rate and admirable tolerability. Particularly, certain 3-substituted indolin-2-one derivatives have met the requirements for clinical trials or the pharmaceutical market. Herein, we focus on the traits of 3-substituted indolin-2-one derivatives as kinase inhibitors for cancer therapy, overview recent progress of 3-substituted indolin-2-one derivatives as kinase inhibitors for cancer therapy, analyze the selectivity for tyrosine kinases inhibitors and serine/threonine kinases inhibitors from the molecular aspects based on the molecular docking studies, summarize the structure-activity relationships (SARs) as selective kinase inhibitors and provide our perspectives for the development of 3-substituted indolin-2-one derivatives as kinase inhibitors for cancer therapy.

I2-Mediated Cross-Dehydrogenative Coupling and Amidation of 3-Aryl Benzofuranones with Aryl Amines for the Synthesis of 3,3-Diaryl Indolin-2-ones

We have developed a protocol for efficient synthesis of indolin-2-ones from benzofuranones and aryl amines using iodine as a mediator. A diverse range of benzofuranones and aryl amines undergo cross-dehydrogenative coupling and amidation of 3-aryl benzofuranones for the cascade reaction to generate products in 24-93% yields. This reaction can be easily scaled-up to give an indolin-2-one in a gram scale. Further chemical manipulation of the products enabled useful transformations of the phenol ring including alkylation, arylation, etc.

Characterization of LDD-2633 as a Novel RET Kinase Inhibitor with Anti-Tumor Effects in Thyroid Cancer

Rearranged during transfection (RET), a receptor tyrosine kinase, is activated by glial cell line-derived neurotrophic factor family ligands. Chromosomal rearrangement or point mutations in RET are observed in patients with papillary thyroid and medullary thyroid carcinomas. Oncogenic alteration of RET results in constitutive activation of RET activity. Therefore, inhibiting RET activity has become a target in thyroid cancer therapy. Here, the anti-tumor activity of a novel RET inhibitor was characterized in medullary thyroid carcinoma cells. The indirubin derivative LDD-2633 was tested for RET kinase inhibitory activity. In vitro, LDD-2633 showed potent inhibition of RET kinase activity, with an IC₅₀ of 4.42 nM. The growth of TT thyroid carcinoma cells harboring an RET mutation was suppressed by LDD-2633 treatment via the proliferation suppression and the induction of apoptosis. The effects of LDD-2633 on the RET signaling pathway were examined; LDD-2633 inhibited the phosphorylation of the RET protein and the downstream molecules Shc and ERK1/2. Oral administration of 20 or 40 mg/kg of LDD-2633 induced dose-dependent suppression of TT cell xenograft tumor growth. The in vivo and in vitro experimental results supported the potential use of LDD-2633 as an anticancer drug for thyroid cancers.

Recent developments of RET protein kinase inhibitors with diverse scaffolds as hinge binders

RET is a proto-oncogene encoding a receptor tyrosine kinase. RET regulates key aspects of cellular proliferation, differentiation and survival. The activation of RET via gene fusions or point mutations is closely related to lung, thyroid and other cancers. This review summarizes the developments of a diversity of small molecule RET protein kinase inhibitors in the past 10 years. These RET inhibitors are classified according to their hinge binder chemotypes as: pyrimidines, including the pyrazolopyrimidines, pyrimidine oxazines, quinazolines, 4-aminopyrimidines and 4-aminopyridines; indolinones; 5-aminopyrazole-4-carboxamides; 3-trifluoromethylanilines; imidazopyridines, imidazopyridazines and pyrazopyridines; nicotinonitriles; pyridones and 1,2,4-triazoles. In each section, the biological activities of the inhibitors, their structure-activity relationships and possible binding modes with the RET kinase are introduced.

Structure-activity relationship studies of indolin-2-one derivatives as vascular endothelial growth factor receptor inhibitors and anticancer agents

Angiogenesis is a requirement for the growth of cancer cells. The family of vascular endothelial growth factor receptors (VEGFRs) is the main target in metastasis. Indolin-2-one is proved to be an essential scaffold of antiangiogenic drugs. Sunitinib is the first oral indolin-2-one derivative marketed as a VEGFR inhibitor in the treatment of renal cell carcinoma and gastrointestinal stromal tumors. Therefore, novel compounds possessing the scaffold of sunitinib were designed and synthesized by different researchers to improve the anticancer activity, bioavailability, and solubility, and to decrease the toxicity of sunitinib. In this comprehensive review, the structure-activity relationship of different indolin-2-one analogs as VEGFR inhibitors is discussed. It has been observed that the indolin-2-one core is necessary for the inhibition of VEGFRs. It was determined that substitutions at C-3 of the oxindole ring play an important role in their antiangiogenic and anticancer activities.

Virtual Screening Identifies Irreversible FMS-like Tyrosine Kinase 3 Inhibitors with Activity toward Resistance-Conferring Mutations

The use of covalent irreversible binding inhibitors is an established concept for drug development. Usually, the discovery of new irreversible kinase inhibitors occurs serendipitously, showing that efficient rational approaches for the rapid discovery of new drugs are needed. Herein, we report a virtual screening strategy that led to the discovery of irreversible inhibitors of FMS-like tyrosine kinase 3 (FLT3) involved in the pathogenesis of acute myeloid leukemia. A virtual screening library was designed to target the highly conserved Cys828 residue preceding the DFG motif by modification of reported reversible inhibitors with chemically reactive groups. Prospective covalent docking allowed the identification of two lead series, resulting in a massive increase in inhibition of kinase activity and cell viability by irreversible inhibitors compared to the corresponding reversible scaffolds. Lead compound 4b (BSc5371) displays superior cytotoxicity in FLT3-dependent cell lines to compounds in recent clinical trials and overcomes drug-resistant mutations.

Selective formation of γ-lactams via C-H amidation enabled by tailored iridium catalysts

Intramolecular insertion of metal nitrenes into carbon-hydrogen bonds to form γ-lactam rings has traditionally been hindered by competing isocyanate formation. We report the application of theory and mechanism studies to optimize a class of pentamethylcyclopentadienyl iridium(III) catalysts for suppression of this competing pathway. Modulation of the stereoelectronic properties of the auxiliary bidentate ligands to be more electron-donating was suggested by density functional theory calculations to lower the C-H insertion barrier favoring the desired reaction. These catalysts transform a wide range of 1,4,2-dioxazol-5-ones, carbonylnitrene precursors easily accessible from carboxylic acids, into the corresponding γ-lactams via sp³ and sp² C-H amidation with exceptional selectivity. The power of this method was further demonstrated by the successful late-stage functionalization of amino acid derivatives and other bioactive molecules.

Design, Synthesis and Preliminary Biological Evaluation of Novel Benzyl Sulfoxide 2-Indolinone Derivatives as Anticancer Agents

In this work, a series of novel benzyl sulfoxide 2-indolinone derivatives was designed and synthesized as potent anticancer agents. Tyrosine kinase inhibitory activity assay indicated that most of the compounds showed significant activity. The in vitro antiproliferative activity of these compounds was further investigated against five human cancer cell lines (HeLa, HepG2, MCF-7, SCC-15, and A549). Several compounds exhibited evident activities. Among them, (Z)-3-(((4-bromobenzyl)sulfinyl)methylene)indolin-2-one (6j) and (Z)-3-((benzylsulfinyl)methylene)-5-bromoindolin-2-one (6o) were found to be effective tyrosine kinase inhibitors (IC₅₀ = 1.34 and 2.69 μM, respectively) in addition to having noteworthy antitumor potential (the average IC₅₀ value of 6j or 6o was less than 40 μM). This class of novel derivatives has promising potential for further development as anticancer agents.

Dynamic, structural and thermodynamic basis of insulin-like growth factor 1 kinase allostery mediated by activation loop phosphorylation

Despite the importance of kinases' catalytic activity regulation in cell signaling, detailed mechanisms underlying their activity regulation are poorly understood. Herein, using insulin-like growth factor 1 receptor kinase (IGF-1RK) as a model, the mechanisms of kinase regulation by its activation loop (A-loop) phosphorylation were investigated through molecular dynamics (MD) and alchemical free energy simulations. Analyses of the simulation results and free energy landscapes determined for the entire catalytic cycle of the kinase revealed that A-loop phosphorylation affects each step in the IGF-1RK catalytic cycle, including conformational change, substrate binding/product release and catalytic phosphoryl transfer. Specifically, the conformational equilibrium of the kinase is shifted by 13.2 kcal mol-1 to favor the active conformation after A-loop phosphorylation, which increases substrate binding affinity of the activated kinase. This free energy shift is achieved primarily via destabilization of the inactive conformation. The free energy of the catalytic reaction is also changed by 3.3 kcal mol-1 after the phosphorylation and in the end, facilitates product release. Analyses of MD simulations showed that A-loop phosphorylation produces these energetic effects by perturbing the side chain interactions around each A-loop tyrosine. These interaction changes are propagated to the remainder of the kinase to modify the orientations and dynamics of the αC-helix and A-loop, and together yield the observed free energy changes. Since many protein kinases share similar interactions identified in this work, the mechanisms of kinase allostery and catalysis unraveled here can be applicable to them.

Design, synthesis and biological evaluation of 3-substituted-2-oxindole hybrid derivatives as novel anticancer agents

The 2-oxindole nucleus is the central core to develop new anticancer agents and its substitution at the 3-position can effect antitumor activity. Utilizing a pharmacophore hybridization approach, a novel series of antiproliferative agents was obtained by the modification of the structure of 3-substituted-2-oxindole pharmacophore by the attachment of the α-bromoacryloyl moiety, acting as a Michael acceptor, at the 5-position of 2-oxindole framework. The impact of the substituent at the 3-position of 2-oxindole core on the potency and selectivity against a panel of seven different cancer cell lines was examined. We found that these hybrid molecules displayed potent antiproliferative activity against a panel of four cancer cell lines, with one-to double digit nanomolar 50% inhibitory concentrations (IC₅₀). A distinctive selective antiproliferative activity was obtained towards CCRF-CEM and RS4; 11 leukemic cell lines. In order to study the possible mechanism of action, we observed that the two most active compounds namely 3(E) and 6(Z) strongly induce apoptosis that follow the mitochondrial pathway. Interestingly a decrease of intracellular reduced glutathione content (GSH) and reactive oxygen species (ROS) production was detected in treated cells compared with controls suggesting that these effects may be involved in their mechanism of action.

RET kinase inhibitors: a review of recent patents (2012-2015)

INTRODUCTION

Tyrosine kinases are involved in the control of several biological processes and have been recognized as hot spots of oncogenic transformation, thus representing a major therapeutic target. Dysregulated activation of RET kinase, either through point mutations or gene fusions, is accountable for a significant fraction of thyroid carcinomas, as well as a minor population of lung cancers. Two drugs are currently available for the treatment of medullary thyroid carcinoma and two additional compounds have been approved for differentiated thyroid carcinoma. Several other molecules are under preclinical and clinical evaluation. Areas covered: This review covers the most recent patent literature (2012-2015) describing compounds with activity against the RET kinase, trying to catch a view of the next generation of potential anti-RET drugs. Expert opinion: RET has been a focus of molecularly targeted efforts for over a decade. However, none of the drugs currently on the clinical stage were specifically developed to hit RET, which was rather an off-target. Besides, only two of four drugs have activity on metastatic medullary carcinoma. Therefore, there is still a need of additional, more potent and more specific RET inhibitors, which will hopefully emerge from the new generation of compounds disclosed in most recent patents.

Synthesis, Biological, and Computational Evaluation of Novel 1,3,5-Substituted Indolin-2-one Derivatives as Inhibitors of Src Tyrosine Kinase

Several substituted indolin-2-one derivatives were synthesized and evaluated for their activities against Src kinase. Several compounds showed activity against Src, with IC50 values in the low micromolar range. Among them, compound 2f showed the most significant activity with an IC50 value of 1.02 μM. Molecular docking studies have been performed for evaluation of the binding modes of compound 2f into the Src active site. The docking structure of compound 2f disclosed that the indole NH forms a hydrogen bond with the carbonyl of Met341. These results suggest that our novel compound 2f is a promising compound for the further development of indole-based drugs targeting Src kinase.

Selective C-arylation of 2,5-dibromo-3-hexylthiophene via Suzuki cross coupling reaction and their pharmacological aspects

The present study reports the synthesis of various new derivatives based on 5-aryl-2-bromo-3-hexylthiophene with moderate-to-good yields via a palladium-catalyzed Suzuki cross-coupling reaction. This coupling method involved the reaction of 2,5-dibromo-3-hexylthiophene with several arylboronic acids in order to synthesize corresponding thiophene derivatives under controlled and optimal reaction conditions. The different substituents (CH₃, OCH₃, Cl, F etc.) present on arylboronic acids are found to have significant electronic effects on the overall properties of new products. The synthesized thiophene molecules were studied for their haemolytic, biofilm inhibition and anti-thrombolytic activities, and almost all products showed potentially good properties. The compound 2-bromo-5-(3-chloro-4-fluorophenyl)-3-hexylthiophenein particular exhibited the highest values for haemolytic and bio-film inhibition activities among all newly synthesized derivatives. In addition, the compound 2-bromo-3-hexyl-5-(4-iodophenyl)thiophene also showed high anti-thrombolytic activity, suggesting the potential medicinal applications of these newly synthesized compounds.

Syntheses and evaluation of carbon-11- and fluorine-18-radiolabeled pan-tropomyosin receptor kinase (Trk) inhibitors: exploration of the 4-aza-2-oxindole scaffold as Trk PET imaging agents

Tropomyosin receptor kinases (TrkA/B/C) are critically involved in the development of the nervous system, in neurological disorders as well as in multiple neoplasms of both neural and non-neural origins. The development of Trk radiopharmaceuticals would offer unique opportunities toward a more complete understanding of this emerging therapeutic target. To that end, we first developed [(11)C]GW441756 ([(11)C]9), a high affinity photoisomerizable pan-Trk inhibitor, as a lead radiotracer for our positron emission tomography (PET) program. Efficient carbon-11 radiolabeling afforded [(11)C]9 in high radiochemical yields (isolated RCY, 25.9% ± 5.7%). In vitro autoradiographic studies in rat brain and TrkB-expressing human neuroblastoma cryosections confirmed that [(11)C]9 specifically binds to Trk receptors in vitro. MicroPET studies revealed that binding of [(11)C]9 in the rodent brain was mostly nonspecific despite initial high brain uptake (SUVmax = 2.0). Modeling studies of the 4-aza-2-oxindole scaffold led to the successful identification of a small series of high affinity fluorinated and methoxy derivatized pan-Trk inhibitors based on our lead compound 9. Out of this series, the fluorinated compound 10 was selected for initial evaluation and radiolabeled with fluorine-18 (isolated RCY, 2.5% ± 0.6%). Compound [(18)F]10 demonstrated excellent Trk selectivity in a panel of cancer relevant kinase targets and a promising in vitro profile in tumors and brain sections but high oxidative metabolic susceptibility leading to nonspecific brain distribution in vivo. The information gained in this study will guide further exploration of the 4-aza-2-oxindole scaffold as a lead for Trk PET ligand development.

Synthesis, biological evaluation and molecular modeling of novel series of pyridine derivatives as anticancer, anti-inflammatory and analgesic agents

This paper presents a combined synthesis; characterization, computational and biological activity studies of novel series of pyridines heterocyclic compounds. The compounds have been characterized by elemental analyses and spectral like IR, (1)H NMR, (13)C NMR and MS studies. Michael addition of substituted-2-methoxycarbonylacetanilide 2a,b on the α-substituted cinnamonitriles 3a-d gave the corresponding 2-pyridone derivatives 5-10. Structures of the titled compounds cited in this article were elucidated by spectrometric data (IR, (1)H NMR, (13)C NMR and MS). The molecular modeling of the synthesized compounds has been drawn and their molecular parameters were calculated. Also, valuable information is obtained from the calculation of molecular parameters including electronegativity, net dipole moment of the compounds, total energy, electronic energy, binding energy, HOMO and LUMO energy. Various in vitro antitumor as well as in vivo anti-inflammatory and analgesic activities of the synthesized compounds were investigated. Evaluation of anti-inflammatory activity of test compounds was performed using carrageenan induced paw edema in rats. All the tested compounds showed moderate to good activity. The SAR results indicate that all compounds showed moderate to good activity, among these 7 and 10 compounds having -N(CH3)2 group are most effective.

Regioselective synthesis of 2-(bromomethyl)-5-aryl-thiophene derivatives via palladium (0) catalyzed suzuki cross-coupling reactions: as antithrombotic and haemolytically active molecules

Background

It is seen that the regioselective functionalizations of halogenated heterocycles play an important role in the synthesis of several types of organic compounds. In this domain, the Suzuki-Miyaura reaction has emerged as a convenient way to build carbon-carbon bonds in synthesizing organic compounds. Some of the most important applications of these reactions can be seen in the synthesis of natural products, and in designing targeted pharmaceutical compounds. Herein, we present the regioselective synthesis of the novel series of 2-(bromomethyl)-5-aryl-thiophenes 3a-i,via Suzuki cross-coupling reactions of various aryl boronic acids with 2-bromo-5-(bromomethyl)thiophene (2).

Results

The synthesized compounds were screened for their haemolytic and antithrombolytic activities. The novel compounds 3f, 3i showed highest 69.7, 33.6% haemolysis of blood cells, respectively. The antithrombolytic activity of the compounds was found to be within low to moderate against human blood clot. The compound 3i showed potent clot lysis (31.5%).

Conclusions

Considering these results, it is concluded that the synthesized compounds can be used as a promising source of therapeutic agents.

Discovery and preclinical profiling of 3-[4-(morpholin-4-yl)-7H-pyrrolo[2,3-d]pyrimidin-5-yl]benzonitrile (PF-06447475), a highly potent, selective, brain penetrant, and in vivo active LRRK2 kinase inhibitor

Leucine rich repeat kinase 2 (LRRK2) has been genetically linked to Parkinson's disease (PD) by genome-wide association studies (GWAS). The most common LRRK2 mutation, G2019S, which is relatively rare in the total population, gives rise to increased kinase activity. As such, LRRK2 kinase inhibitors are potentially useful in the treatment of PD. We herein disclose the discovery and optimization of a novel series of potent LRRK2 inhibitors, focusing on improving kinome selectivity using a surrogate crystallography approach. This resulted in the identification of 14 (PF-06447475), a highly potent, brain penetrant and selective LRRK2 inhibitor which has been further profiled in in vivo safety and pharmacodynamic studies.

Identification of two novel RET kinase inhibitors through MCR-based drug discovery: design, synthesis and evaluation

From an MCR fragment library, two novel chemical series have been developed as inhibitors of RET, which is a kinase involved in the pathology of medullary thyroid cancer (MTC). Structure activity relationship studies (SAR) identified two sub-micromolar tractable leads, 6g and 13g. 6g was confirmed to be a Type-II RET inhibitor. 13g and 6g inhibited RET in cells transformed by RET/C634. A RET DFG-out homology model was established and utilized to predict Type-II inhibitor binding modes.

Synthesis, antimicrobial, anticancer, antiviral evaluation and QSAR studies of 4-(1-aryl-2-oxo-1,2-dihydro-indol-3-ylideneamino)-N-substituted benzene sulfonamides

A series of 4-(1-aryl-2-oxo-1,2-dihydro-indol-3-ylideneamino)-N-substituted benzenesulfonamide derivatives (1-32) was synthesized and evaluated for its in vitro antimicrobial, antiviral and cytotoxic activities. Antimicrobial results indicated that compounds (11) and (18) were found to be the most effective ones. In general, the synthesized compounds were bacteriostatic and fungistatic in their action. The cytotoxic screening results indicated that the compounds were less active than the standard drug 5-fluorouracil (5-FU). None of the compounds inhibited viral replication at subtoxic concentrations. In general, the presence of a pyrimidine ring with electron releasing groups and an ortho- and para-substituted benzoyl moiety favored antimicrobial activities. The results of QSAR studies demonstrated the importance of topological parameters, valence zero order molecular connectivity index (0χv) and valence first order molecular connectivity index (1χv) in describing the antimicrobial activity of synthesized compounds.

Mechanisms of RET signaling in cancer: current and future implications for targeted therapy

De-regulation of RET signaling by oncogenic mutation, gene rearrangement, overexpression or transcriptional up-regulation is implicated in several human cancers of neuroendocrine and epithelial origin (thyroid, breast, lung). Understanding how RET signaling mechanisms associated with these oncogenic events are deregulated, and their impact in the biological processes driving tumor formation and progression, as well as response to treatment, will be crucial to find and develop better targeted therapeutic strategies. In this review we emphasie the distinct mechanisms of RET signaling in cancer and summarise current knowledge on small molecule inhibitors targeting the tyrosine kinase domain of RET as therapeutic drugs in RET-positive cancers.

Oncogenic RET kinase domain mutations perturb the autophosphorylation trajectory by enhancing substrate presentation in trans

To decipher the molecular basis for RET kinase activation and oncogenic deregulation, we defined the temporal sequence of RET autophosphorylation by label-free quantitative mass spectrometry. Early autophosphorylation sites map to regions flanking the kinase domain core, while sites within the activation loop only form at later time points. Comparison with oncogenic RET kinase revealed that late autophosphorylation sites become phosphorylated much earlier than wild-type RET, which is due to a combination of an enhanced enzymatic activity, increased ATP affinity, and surprisingly, by providing a better intermolecular substrate. Structural analysis of oncogenic M918T and wild-type RET kinase domains reveal a cis-inhibitory mechanism involving tethering contacts between the glycine-rich loop, activation loop, and αC-helix. Tether mutations only affected substrate presentation but perturbed the autophosphorylation trajectory similar to oncogenic mutations. This study reveals an unappreciated role for oncogenic RET kinase mutations in promoting intermolecular autophosphorylation by enhancing substrate presentation.

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Kinetics of RET autophosphorylation identify early and late autophosphorylation sites

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Evidence for a RET kinase domain cis-inhibitory tether is presented

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Oncogenic RET subverts cis-inhibition and perturbs the autophosphorylation trajectory

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Oncogenic RET kinase is overactive and a better trans-autophosphorylation substrate

Substituted indolin-2-ones as p90 ribosomal S6 protein kinase 2 (RSK2) inhibitors: Molecular docking simulation and structure-activity relationship analysis

A series of novel indolin-2-ones inhibitors against p90 ribosomal S6 protein kinase 2 (RSK2) were designed and synthesized and their structure-activity relationship (SAR) was studied. The most potent inhibitor, compound 3s, exhibited potent inhibition against RSK2 with an IC50 value of 0.5 μM and presented a satisfactory selectivity against 23 kinases. The interactions of these inhibitors with RSK2 were investigated based on the proposed binding poses with molecular docking simulation. Four compounds and six compounds exhibited moderate anti-proliferation activities against PC 3 cells and MCF-7 cells, respectively.

Synthesis and biological evaluation of 2-(5-substituted-1-((diethylamino)methyl)-2-oxoindolin-3-ylidene)-N-substituted-hydrazinecarbothioamides

Abstract

Various 5-substituted-2-(1-((diethylamino)methyl)-2-oxoindolin-3-ylidene)hydrazinecarbothioamide (4a, b) and 5-substituted-2-(1-((diethylamino)methyl)-2-oxoindolin-3-ylidene)-N-(phenyl-4-substituted)hydrazinecarbothioamide (5a–h) derivatives were synthesized. The compounds were screened for cytotoxicity against human HeLa and CEM T-lymphocytes as well as murine L1210 cells. The compounds were also screened for β-lactamase inhibitory activity, antiviral, antibacterial, and antifungal activity against various strains of microorganisms. Several of these compounds were endowed with low micromolar 50 %-cytostatic concentration (IC₅₀) values, and some were virtually equally potent as melphalan. The most potent inhibitors against the murine leukemia cells (L1210) were also the most inhibitory against human T-lymphocyte (CEM) tumor cells. Derivative 2-(1-((diethylamino)methyl)-2-oxoindolin-3-ylidene)-N-(4-methoxyphenyl)hydrazinecarbothioamide 5c emerged as the most potent cytostatic compound among the tested compounds. Derivatives 4b, 5a, 5b, and 5d showed antiviral activity against HEL cell cultures (IC₅₀ 11–20 μM). Moderate antimicrobial activity was observed for all derivatives. The encouraging cytostatic and antiviral activity data provide an adequate rationale for further modification of these molecular scaffolds.

Graphical abstract

Derivative 5c (1.9–4.4 μM) emerged as the most potent cytostatic compound among the tested compounds. Derivatives 4b, 5a, 5b, and 5d showed antiviral activity against HEL cell cultures (IC₅₀ 11–20 μM).