Synthesis and biological evaluation of 4-anilinoquinolines as potent inhibitors of epidermal growth factor receptor

Catalyst-free late-stage functionalization to assemble α-acyloxyenamide electrophiles for selectively profiling conserved lysine residues

Covalent probes coupled with chemical proteomics represent a powerful method for investigating small molecule and protein interactions. However, the creation of a reactive warhead within various ligands to form covalent probes has been a major obstacle. Herein, we report a convenient and robust process to assemble a unique electrophile, an α-acyloxyenamide, through a one-step late-stage coupling reaction. This procedure demonstrates remarkable tolerance towards other functional groups and facilitates ligand-directed labeling in proteins of interest. The reactive group has been successfully incorporated into a clinical drug targeting the EGFR L858R mutant, erlotinib, and a pan-kinase inhibitor. The resulting probes have been shown to be able to covalently engage a lysine residue proximal to the ATP-binding pocket of the EGFR L858R mutant. A series of active sites, and Mg2+, ATP-binding sites of kinases, such as K33 of CDK1, CDK2, CDK5 were detected. This is the first report of engaging these conserved catalytic lysine residues in kinases with covalent inhibition. Further application of this methodology to natural products has demonstrated its success in profiling ligandable conserved lysine residues in whole proteome. These findings offer insights for the development of new targeted covalent inhibitors (TCIs).

One-Pot Synthesis of 1-Thia-4-azaspiro[4.4/5]alkan-3-ones via Schiff Base: Design, Synthesis, and Apoptotic Antiproliferative Properties of Dual EGFR/BRAFV600E Inhibitors

In this investigation, novel 4-((quinolin-4-yl)amino)-thia-azaspiro[4.4/5]alkan-3-ones were synthesized via interactions between 4-(2-cyclodenehydrazinyl)quinolin-2(1H)-one and thioglycolic acid catalyzed by thioglycolic acid. We prepared a new family of spiro-thiazolidinone derivatives in a one-step reaction with excellent yields (67-79%). The various NMR, mass spectra, and elemental analyses verified the structures of all the newly obtained compounds. The antiproliferative effects of 6a-e, 7a, and 7b against four cancer cells were investigated. The most effective antiproliferative compounds were 6b, 6e, and 7b. Compounds 6b and 7b inhibited EGFR with IC₅₀ values of 84 and 78 nM, respectively. Additionally, 6b and 7b were the most effective inhibitors of BRAF^V600E (IC₅₀ = 108 and 96 nM, respectively) and cancer cell proliferation (GI₅₀ = 35 and 32 nM against four cancer cell lines, respectively). Finally, the apoptosis assay results revealed that compounds 6b and 7b had dual EGFR/BRAF^V600E inhibitory properties and showed promising antiproliferative and apoptotic activity.

2-Arylquinolines as novel anticancer agents with dual EGFR/FAK kinase inhibitory activity: synthesis, biological evaluation, and molecular modelling insights

In this study, different assortments of 2-arylquinolines and 2,6-diarylquinolines have been developed. Recently, we have developed a new series of 6,7-dimethoxy-4-alkoxy-2-arylquinolines as Topoisomerase I (TOP1) inhibitors with potent anticancer activity. Utilising the SAR outputs from this study, we tried to enhance anticancer and TOP1 inhibitory activities. Though target quinolines demonstrated potent antiproliferative effect, specifically against colorectal cancer DLD-1 and HCT-116, they showed weak TOP1 inhibition which may be attributable to their non-coplanarity. Thereafter, screening against kinase panel revealed their dual inhibitory activity against EGFR and FAK. Quinolines 6f, 6h, 6i, and 20f were the most potent EGFR inhibitors (IC50s = 25.39, 20.15, 22.36, and 24.81 nM, respectively). Meanwhile, quinolines 6f, 6h, 6i, 16d, and 20f exerted the best FAK inhibition (IC50s = 22.68, 14.25, 18.36, 17.36, and 15.36 nM, respectively). Finally, molecular modelling was employed to justify the promising EGFR/FAK inhibition. The study outcomes afforded the first reported quinolines with potent EGFR/FAK dual inhibition.

Click ferrocenyl-erlotinib conjugates active against erlotinib-resistant non-small cell lung cancer cells in vitro

Thanks to development of erlotinib and other target therapy drugs the lung cancer treatment have improved a lot in recent years. However, erlotinib-resistant lung cancer remains an unsolved clinical problem which demands for new therapeutics to be developed. Herein we report the synthesis of a library of 1,4- and 1,5-triazole ferrocenyl derivatives of erlotinib together with their anticancer activity studies against erlotinib-sensitive A549 and H1395 as well as erlotinib-resistant H1650 and H1975 cells. Studies showed that extend of anticancer activity is mainly related to the length of the spacer between the triazole and the ferrocenyl entity. Among the series of investigated compounds two isomers commonly bearing C(O)CH₂CH₂ spacer have shown superior to erlotinib activity against erlotinib-resistant H1650 and H1975 cells whereas compound with short methylene spacer devoid of any activity. In-depth biological studies for the most active compound showed differences in its mechanism of action in compare to erlotinib. The latter is known EGFR inhibitor whereas their ferrocenyl congener exerts anticancer activity mainly as ROS-inducer which activates mitochondrial pathway of apoptosis in cancer cells. However, docking studies suggested that the most active compound can also binds to the active site of EGFR TK in a similar way as erlotinib.

Building 2D classification models and 3D CoMSIA models on small-molecule inhibitors of both wild-type and T790M/L858R double-mutant EGFR

Epidermal growth factor receptor (EGFR) has received widespread attention because it is an important target for anticancer drug design. Mutations in the EGFR, especially the T790M/L858R double mutation, have made cancer treatment more difficult. We herein built the structure-activity relationship models of small-molecule inhibitors on wild-type and T790M/L858R double-mutant EGFR with a whole dataset of 379 compounds. For 2D classification models, we used ECFP4 fingerprints to build support vector machine and random forest models and used SMILES to build self-attention recurrent neural network models. Each of all six models resulted in an accuracy of above 0.87 and the Matthews correlation coefficient value of above 0.76 on the test set, respectively. We concluded that inhibitors containing anilinoquinoline and methoxy or fluoro phenyl are highly active against wild EGFR. Substructures such as anilinopyrimidine, acrylamide, amino phenyl, methoxy phenyl, and thienopyrimidinyl amide appeared more in highly active inhibitors against double-mutant EGFR. We also used self-organizing map to cluster the inhibitors into six subsets based on ECFP4 fingerprints and analyzed the activity characteristics of different scaffolds in each subset. Among them, three datasets, which are based on pteridin, anilinopyrimidine, and anilinoquinoline scaffold, were selected to build 3D comparative molecular similarity analysis models individually. Models with the leave-one-out coefficient of determination (q²) above 0.65 were selected, and five descriptor types (steric, electrostatic, hydrophobic, donor, and acceptor) were used to study the effects of side chains of inhibitors on the activity against wild-type and mutant-type EGFR.

EGFRisopred: a machine learning-based classification model for identifying isoform-specific inhibitors against EGFR and HER2

The EGFR kinase pathway is one of the most frequently activated signaling pathways in human cancers. EGFR and HER2 are the two significant members of this pathway, which are attractive drug targets of clinical relevance in lung and breast cancer. Therefore, identifying EGFR- and HER2-specific inhibitors is one of the important challenges in cancer drug discovery. To address this issue, a dataset of 519 compounds having inhibitory activity against both the isoforms, i.e., EGFR and HER2, was collected from the literature and developed a knowledge-based computational classification model for predicting the specificity of a molecule for an isoform (EGFR/HER2) with precision. A total of seventy-two classification models using nine fingerprint types, four classifiers (IBK, NB, SMO and RF) and two different datasets (EGFR and HER2 isoform specific) were developed. It was observed that the models developed using random forest and IBK performed better for EGFR- and HER2-specific datasets, respectively. Scaffold and functional group analysis led to the identification of prevalent core and fragments in each of the datasets. The accuracy of the selected best performing models was also evaluated using the decoy dataset. We have also developed an application EGFRisopred, which integrates the best performing models and permits the user to predict the specificity of a compound as an EGFR-/HER2-specific anticancer agent. It is expected that the tool's availability as a free utility will allow researchers to identify new inhibitors against these targets important in cancer.

Discovery of 4-alkoxy-2-aryl-6,7-dimethoxyquinolines as a new class of topoisomerase I inhibitors endowed with potent in vitro anticancer activity

In our attempt to develop potential anticancer agents targeting Topoisomerase I (TOP1), two novel series of 4-alkoxy-2-arylquinolines 14a-p and 19a-c were designed and synthesized based on structure activity relationships of the reported TOP1 inhibitors and structural features required for stabilization of TOP1-DNA cleavage complexes (TOP1ccs). The in vitro anticancer activity of these two series of compounds was evaluated at one dose level using NCI-60 cancer cell lines panel. Compounds 14e-h and 14m-p, with p-substituted phenyl at C2 and propyl linker at C4, were the most potent and were selected for assay at five doses level in which they exhibited potent anticancer activity at sub-micromolar level against diverse cancer cell lines. Compound 14m was the most potent with full panel GI₅₀ MG-MID 1.26 μM and the most sensitive cancers were colon cancer, leukemia and melanoma with GI₅₀ MG-MID 0.875, 0.904 and 0.926 μM, respectively. Melanoma (LOX IMVI) was the most sensitive cell line to all tested compounds displaying GI₅₀ from 0.116 to 0.227 μM, TGI from 0.275 to 0.592 μM and LC₅₀ at sub-micromolar concentration against almost of the tested compounds. Compounds 14e-h and 14m-p were assayed using TOP1-mediated DNA cleavage assay to evaluate their ability to stabilize TOP1ccs resulting in cancer cell death. The morpholino analogs 14h and 14p exhibited moderate TOP1 inhibitory activity compared to 1 μM camptothecin suggesting their use as lead compounds that can be optimized for the development of more potent anticancer agents with potential TOP1 inhibitory activity. Finally, Swiss ADME online web tool predicted that compounds 14h and 14p possessed good oral bioavailability and druglikeness characteristics.

Novel 4-Anilinoquinazoline Derivatives as Potent Anticancer Agents: Design, Synthesis, Cytotoxic Activity, and Docking Study

The simultaneous inhibition of EGFR and VEGFR-2 is a promising method in cancer treatment. In the present work, several 4-anilinoquinazoline derivatives encompassing different substitutions at the C-4 and C-7 positions of a quinazoline core were designed, synthesised, and evaluated for their cytotoxicity on A431, HUVEC, and HU02 cell lines. Docking studies were carried out to test the interactions of all synthesised compounds with EGFR and VEGFR-2. Furthermore, a wound healing assay was done for the investigation of cell migration. The most potent compound was 8l followed by the compounds 8i and 8j which showed better cytotoxic activities on A431 and HUVEC cell lines than the standard (Vandetanib). The compounds 8f and 8a represented the best docking energies of 8.99 and 9.35 kcal mol−1 for EGFR and VEGFR, respectively. Moreover, molecular docking studies exhibited that compound 8l showed efficient binding affinity against both EGFR and VEGFR-2. It can bind to these receptors through the formation of essential hydrogen bonds between the quinazoline N1 atom and the Met796 backbone of EGFR and two hydrogen bonds with Cys919 and Thr916 of VEGFR-2 with energies of –7.99 and –7.85 kcal mol−1, respectively. In addition, this compound displayed the highest activity on cell migration and wound healing. Compound 8l with the highest cytotoxic activity can be considered a candidate for further investigation and structural optimisation as an antiproliferative agent.

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.

A preliminary study on quinazolinylaminobenzoyl monopeptide esters as effective Gram-positive bacteriostatic agents

AIM

To investigate a novel series of quinazoline monopeptide esters for the in vitro antibacterial activity.

METHODOLOGY/RESULTS

The compounds were synthesized via one-pot Dimroth rearrangement of suitable formamidine intermediates with 3-aminobenzoic acid, followed by coupling the resulting acids with amino acid esters and screening for their antibacterial activity by broth dilution method. The compounds 5a, 5b, 5c, 5g, 5i and 5j showed promising activity against the Gram-positive bacteria, 5c and 5g being the most potent against Enterococcus faecalis and Staphylococcus aureus, respectively, with a minimal inhibitory concentration of 0.51 μM. The percentage hemolysis of the compounds ranged from 2.79 to 12.92 at a concentration of 100 μg/ml. The molecular docking studies revealed their GlmU inhibitory action.

CONCLUSION

The compounds 5a and 5g emerged as antibacterial hits.

Synthesis, Cytotoxic Evaluation, and Molecular Docking Studies of N-(7- hydroxy-4-methyl-2-oxoquinolin-1(2H)-yl)acetamide/benzamide Analogues

Background:

Cancer caused nearly 8.8 million deaths in 2015. Limited efficacy, selectivity, drug resistance and toxicity are major complications associated with chemotherapy, potentiating the discovery of anticancer agents.

Methods:

A new series of N-(7-hydroxy-4-methyl-2-oxoquinolin-1(2H)-yl)acetamide/benzamide analogues (5a-j) was prepared from the precursor, 7-hydroxy-4-methyl-2H-chromen-2-one (3), as anticancer agent. The structural assignment of quinolone analogues (5a-j) was based on spectroscopic data analyses. The cytotoxicity was tested on breast cancer cell lines (MCF7 and MDA-MB- 231) by sulforhodamine B (SRB) assay and three dose-related parameters GI50, TGI, and LC50 were calculated.

Results:

2-(2-chlorophenoxy)-N-(7-hydroxy-4-methyl-2-oxoquinolin-1(2H)-yl)acetamide (5a) showed the most potent cytotoxicity against the MCF7 and MDA-MB-231 cancer cell lines with GI50 of 18.7 and 48.1 µM respectively. The glide scores of the compounds, 5a-d were found to be related to the cytotoxicity profile and the emodel scores for ligands, 5a-j were found to be related to significant cytotoxicity.

Conclusion:

Compound 5a exhibited the most potent cytotoxicity and this report may provide some predictions to design more potent novel quinolines as cytotoxic agents.

Synthesis, docking and anticancer activity of azo-linked hybrids of 1,3,4-thia-/oxadiazoles with cyclic imides

A series of novel analogues based on a diazole-imide pharmacophore were synthesized by diazotizing substituted 1,3,4-thia-/oxadiazol-2-amines and subsequently coupling the resulting diazonium salts with N-substituted cyclic imides. The resulting compounds C1 to C28 were characterized by various spectral methods, viz. IR, NMR and mass spectroscopy. All the synthesized compounds were tested against two human cancer cell lines: human breast adenocarcinoma cell line MCF-7 and colorectal adenocarcinoma cell line HT-29. Among the synthesized compounds, C14 (2-(4-chloro-3-((5-(4-nitrophenyl)-1,3,4-thiadiazol-2-yl)diazenyl)phenyl)-4,5,6,7-tetrahydro-1H-isoindole-1,3(2H)-dione) emerged as a potential candidate against both MCF-7 and HT-29 with [Formula: see text] values of 0.09 ± 0.02 [Formula: see text]M and 0.11 ± 0.03 [Formula: see text]M, respectively. Similarly, compound C16 displayed highest anticancer activity against MCF-7 cell line with [Formula: see text] = 0.07 ± 0.02 [Formula: see text]M. Target fishing (inverse docking) using ChemMapper server identified EGFR tyrosine and CDK2 kinases as high priority targets for this pharmacophore. Computational docking (AutoDock 4.2) was used to analyse the interactions between the target proteins and active compounds.

Novel series of 6-(2-substitutedacetamido)-4-anilinoquinazolines as EGFR-ERK signal transduction inhibitors in MCF-7 breast cancer cells

Epidermal growth factor receptor (EGFR) signaling pathway has been previously investigated for its significant role in the progression of different types of malignant tumors, where development of small molecules targeting EGFR is well known strategy for design of antitumor agents. Herein, we report the design and synthesis of two series of 6-(2-substitutedacetamido)-4-anilinoquinazolines (6a-x and 13a-d) as EGFR inhibitors. All the newly synthesized quinazoline derivatives were in vitro evaluated for their anti-proliferative activity towards MCF-7 (Breast Cancer) and HepG2 (Hepatocellular carcinoma) cell lines. In particular, compound 6n showed significant inhibitory activity against MCF-7 and HepG2 cell lines (IC₅₀ = 3 and 16 μM, respectively), compared to that of Erlotinib (IC₅₀ = 20 and 25 μM, respectively). Western blotting of 6n at MCF-7 cell line revealed the dual inhibitory activity of 6n towards diminishing the phosphorylated levels for EGFR and ERK. Also, ELISA assay confirmed the anti-EGFR activity of compound 6n (IC₅₀ = 0.037 μM). Finally, a molecular docking study showed the potential binding mode of 6n within the ATP catalytic binding site of EGFR, exhibiting similar binding mode to EGFR inhibitor Erlotinib.

Synthesis and biological evaluation of 2-styrylquinolines as antitumour agents and EGFR kinase inhibitors: molecular docking study

A new series of 4,6-disubstituted 2-(4-(dimethylamino)styryl)quinoline 4a,b–9a,b was synthesized by the reaction of 2-(4-(dimethylamino)styryl)-6-substituted quinoline-4-carboxylic acids 3a,b with thiosemicarbazide, p-hydroxybenzaldehyde, ethylcyanoacetate, and 2,4-pentandione. In addition, the antitumour activity of all synthesized compounds 3a,b–9a,b was studied via MTT assay against two cancer cell lines (HepG2 and HCT116). Furthermore, epidermal growth factor receptor (EGFR) inhibition, using the most potent antitumour compounds, 3a, 3b, 4a, 4b, and 8a, was evaluated. The interpretation of the results showed clearly that the derivatives 3a, 4a, and 4b exhibited the highest antitumour activities against the tested cell lines HepG2 and HCT116 with IC₅₀ range of 7.7–14.2 µg/ml, in comparison with the reference drugs 5-fluorouracil (IC₅₀ = 7.9 and 5.3 µg/ml, respectively) and afatinib (IC₅₀ = 5.4 and 11.4 µg/ml, respectively). In vitro EGFR screening showed that compounds 3a, 3b, 4a, 4b, and 8a exhibited moderate inhibition towards EGFR with IC₅₀ values at micromolar levels (IC₅₀ range of 16.01–1.11 µM) compared with the reference drugs sorafenib (IC₅₀ = 1.14 µM) and erlotinib (IC₅₀ = 0.1 µM). Molecular docking was performed to study the mode of interaction of compounds 3a and 4b with EGFR kinase.

Identification and Optimization of 4-Anilinoquinolines as Inhibitors of Cyclin G Associated Kinase

4-Anilinoquinolines were identified as potent and narrow-spectrum inhibitors of the cyclin G associated kinase (GAK), an important regulator of viral and bacterial entry into host cells. Optimization of the 4-anilino group and the 6,7-quinoline substituents produced GAK inhibitors with nanomolar activity, over 50 000-fold selectivity relative to other members of the numb-associated kinase (NAK) subfamily, and a compound (6,7-dimethoxy-N-(3,4,5-trimethoxyphenyl)quinolin-4-amine; 49) with a narrow-spectrum kinome profile. These compounds may be useful tools to explore the therapeutic potential of GAK in prevention of a broad range of infectious and systemic diseases.

Synthesis and biological assay of erlotinib analogues and BSA-conjugated erlotinib analogue

A series of erlotinib analogues that have structural modification at 6,7-alkoxyl positions is efficiently synthesized. The in vitro anti-tumor activity of synthesized compounds is studied in two non-small cell lung cancer (NSCLC) cell lines (A549 and H1975). Among the synthesized compounds, the iodo compound 6 (ETN-6) exhibits higher anti-cancer activity compared to erlotinib. An efficient method is developed for the conjugation of erlotinib analogue-4, alcohol compound, with protein, bovine serum albumin (BSA), via succinic acid linker. The in vitro anti-tumor activity of the protein attached erlotinib analogue, 8 (ETN-4-Suc-BSA), showed stronger inhibitory activity in both A549 and H1975 NSCLC cell lines.

Docking study, synthesis and antimicrobial evaluation of some novel 4-anilinoquinazoline derivatives

A series of novel 4-anilinoquinazoline derivatives were designed and synthesized from benzoic acid through ring closure, chlorination or nucleophilic substitution. The structures of compounds were characterized by IR, ¹H-NMR and mass spectroscopy. All synthesized derivatives were screened for their antimicrobial activities against Gram-positive (Staphylococcus aurous, Bacillus subtilis, Listeria monocitogenes) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa, Salmonella entritidis) bacteria and also for antifungal activities against Candida albicans using the conventional micro dilution method. Most of the compounds have shown good antibacterial activities, especially compound 4c having highest activities against E. coli at 32 μg/mL concentration while the tested compounds did not exhibited remarkable antifungal activities. The potential DNA gyrase inhibitory activity of these compounds was investigated in silico using molecular docking simulation method. All compounds showed good results especially compound 4c which showed the lowest ΔG_bind results (-8.16 Kcal/mol).

Synthesis and Anti-Tumor Activities of 4-Anilinoquinoline Derivatives

Twenty-two 7-fluoro (or 8-methoxy)-4-anilinoquinolines compounds were designed and synthesized as potentially potent and selective antitumor inhibitors. All the prepared compounds were evaluated for their in vitro antiproliferative activities against the HeLa and BGC823 cell lines. Ten compounds (1a–g; 2c; 2e and 2i) exhibited excellent antitumor activity superior to that of gefitinib. Among the ten compounds; seven (1a–c; 1e–1g and 2i) displayed excellent selectivity for BGC823 cells. In particular; 1f and 2i exhibited potent cytotoxic activities against HeLa cells and BGC823 cells with better IC₅₀ values than gefitinib.

Exploration of potential EGFR inhibitors: a combination of pharmacophore-based virtual screening, atom-based 3D-QSAR and molecular docking analysis

Epidermal growth factor receptor (EGFR) protein tyrosine kinases are over expressed in several human cancers and considered as a promising target for developing novel anticancer drugs. In this study, the ligand-based pharmacophore mapping and atom-based 3D-QSAR approach was carried out on a series of 40 novel pyrrolo[3, 2-d]pyrimidine derivatives acting as EGFR inhibitors. The best pharmacophore hypothesis AAADRR.295 was selected and an atom-based 3D-QSAR model was generated by applying partial least-squares algorithm. The developed model was validated and used as a 3D query in sequential virtual screening study to filter five chemical databases. The obtained compounds were further filtered according to Lipinski rule of five and fitness score. Subsequently, a multistep molecular docking study was employed on the retrieved hits and finally, 12 compounds were prioritized as potential leads against EGFR, which exhibited high docking scores, correlated binding mode to experimentally proven compounds and constructive drug-like properties. The results of this study provide detailed structural insights and emphasize the important binding features of these compounds, which may assists in the design and development of novel EGFR inhibitors.

A review on anticancer potential of bioactive heterocycle quinoline

The advent of Camptothecin added a new dimension in the field anticancer drug development containing quinoline motif. Quinoline scaffold plays an important role in anticancer drug development as their derivatives have shown excellent results through different mechanism of action such as growth inhibitors by cell cycle arrest, apoptosis, inhibition of angiogenesis, disruption of cell migration, and modulation of nuclear receptor responsiveness. The anti-cancer potential of several of these derivatives have been demonstrated on various cancer cell lines. In this review we have compiled and discussed specifically the anticancer potential of quinoline derivatives, which could provide a low-height flying bird's eye view of the quinoline derived compounds to a medicinal chemist for a comprehensive and target oriented information for development of clinically viable anticancer drugs.

Optimization of substituted 6-salicyl-4-anilinoquinazoline derivatives as dual EGFR/HER2 tyrosine kinase inhibitors

4-Anilinoquinazolines as an important class of protein kinase inhibitor are widely investigated for epidermal growth factor receptor (EGFR) tyrosine kinase or epidermal growth factor receptor 2 (HER2) inhibition. A series of novel 6-salicyl-4-anilinoquinazoline derivatives 9–27 were prepared and evaluated for their EGFR/HER2 tyrosine kinase inhibitory activity as well as their antiproliferative properties on three variant cancer cell lines (A431, MCF-7, and A549). The bioassay results showed most of the designed compounds exhibited moderate to potent in vitro inhibitory activity in the enzymatic and cellular assays, of which compound 21 revealed the most potent dual EGFR/HER2 inhibitory activity, with IC₅₀ values of 0.12 µM and 0.096 µM, respectively, comparable to the control compounds Erlotinib and Lapatinib. Furthermore, the kinase selectivity profile of 21 was accessed and demonstrated its good selectivity over the majority of the close kinase targets. Docking simulation was performed to position compound 21 into the EGFR/HER2 active site to determine the probable binding pose. These new findings along with molecular docking observations could provide an important basis for further development of compound 21 as a potent EGFR/HER2 dual kinase inhibitor.

In silico design: extended molecular dynamic simulations of a new series of dually acting inhibitors against EGFR and HER2

Based on the hit structures that have been identified in our previous studies against EGFR and HER2, new potential inhibitors that share the same scaffold of the hit structures are designed and screened in silico. Insights into understanding the potential inhibitory effect of the new inhibitors against both EGFR and HER2 receptors is obtained using extended molecular dynamics (MD) simulations and different scoring techniques. The binding mechanisms and dynamics are detailed with respect to two approved inhibitors against EGFR (lapatinib) and HER2 (SYR127063). The best scoring inhibitor (T9) is chosen for additional in silico investigation against both the wild-type and T790M mutant strain of EGFR and the wild-type HER2. The results reveal that certain substitution patterns increase the stability and assure stronger binding and higher H-bond occupancy of the conserved water molecule that is commonly observed with kinase crystal structures. Furthermore, the new inhibitor (T9) forms stable interactions with the mutant strain as a direct consequence of the enhanced ability to form additional hydrogen bonding interactions with binding site residues.

Targeting GSK3 from Ustilago maydis: type-II kinase inhibitors as potential antifungals

Protein kinases are key enzymes in the complex regulation of cellular processes in almost all living organisms. For this reason, protein kinases represent attractive targets to stop the growth of eukaryotic pathogens such as protozoa and fungi. However, using kinase inhibitors to fight against these organisms bears several challenges since most of them are unselective and will also affect crucial host kinases. Here we present the X-ray structure of glycogen synthase kinase 3 from the fungal plant pathogen Ustilago maydis (UmGSK3) and its inhibition by type-II kinase inhibitors. Despite the high sequence homology between the human and the fungal variant of this vital kinase, we found substantial differences in the conformational plasticity of their active sites. Compounds that induced such conformational changes could be used to selectively inhibit the fungal kinase. This study serves as an example of how species-specific selectivity of inhibitors can be achieved by identifying and addressing the inactive state of a protein kinase. In addition to this, our study gives interesting insights into the molecular plasticity of UmGSK3 by revealing a previously unknown inactive conformation of this important kinase family.

Synthesis of New 6-{[ω-(Dialkylamino(heterocyclyl)alkyl]thio}-3-R-2H-[1,2,4]triazino[2,3-c]quinazoline-2-ones and Evaluation of their Anticancer and Antimicrobial Activities

Several novel 6-thio-3-R-2-oxo-2H-[1,2,4]triazino[2,3-c]quinazoline-based compounds containing an ω-(dialkylamino(heterocyclyl)]alkyl fragment were synthesized to examine their anticancer activity. Some of the 6-{[ω-(hetero-cyclyl)alkyl]thio}-3-R-2H-[1,2,4]triazino[2,3-c]quinazoline-2-ones (3.1-3.10) were obtained by the nucleophilic substitution of 6-[ω-halogenalkyl]thio-3-R-2H-[1,2,4]triazino[2,3-c]quinazoline-2-ones (2.1-2.8) with azaheterocycles. Alternatively, compounds 3.1-3.22 were synthesized by alkylation of 3-R-6-thio-2H-[1,2,4]triazino[2,3-c]quinazoline-2-ones potassium salts (1.1-1.4) with (2-chloroethyl)-N,N-dialkylamine hydrochlorides or 1-(2-chloroethyl)heterocycle hydrochlorides. The structures of compounds were elucidated by (1)H, (13)C NMR, LC-MS and EI-MS analysis. Then anticancer and antibacterial, bioluminescence inhibition of Photobacterium leiognathi Sh1 activities of the substances were tested in vitro. It was found that compound 3.18 possessed a wide range of anticancer activity against 27 cell lines of cancer: non-small cell lung, colon, CNS, ovarian, renal, prostate, breast, melanoma and leukemia (log GI(50) < -5.65). The "structure-activity" relationship was discussed. COMPARE analysis for synthesized anticancer active compounds was performed.

Prediction of inhibitory activity of epidermal growth factor receptor inhibitors using grid search-projection pursuit regression method

The epidermal growth factor receptor (EGFR) protein tyrosine kinase (PTK) is an important protein target for anti-tumor drug discovery. To identify potential EGFR inhibitors, we conducted a quantitative structure–activity relationship (QSAR) study on the inhibitory activity of a series of quinazoline derivatives against EGFR tyrosine kinase. Two 2D-QSAR models were developed based on the best multi-linear regression (BMLR) and grid-search assisted projection pursuit regression (GS-PPR) methods. The results demonstrate that the inhibitory activity of quinazoline derivatives is strongly correlated with their polarizability, activation energy, mass distribution, connectivity, and branching information. Although the present investigation focused on EGFR, the approach provides a general avenue in the structure-based drug development of different protein receptor inhibitors.

Synthesis and biological evaluation of 7-substituted-1-(3-bromophenylamino)isoquinoline-4-carbonitriles as inhibitors of myosin light chain kinase and epidermal growth factor receptor

Here we present the synthesis and biological activity of a series of 7-substituted-1-(3-bromophenylamino)isoquinoline-4-carbonitriles as inhibitors of myosin light chain kinase (MLCK) and the epidermal growth factor receptor kinase (EGFR). The inhibitory effect of these molecules was found to be dependent on the nature of the substituents at the 7-position of the isoquinoline scaffold.