The discovery of thienopyridine analogues as potent IκB kinase β inhibitors. Part II

Quantum mechanics and 3D-QSAR studies on thienopyridine analogues: inhibitors of IKKβ

Inhibitor of kappa B kinase subunit β (IKKβ) is a main regulator of nuclear factor kappa B (NF-κB) and has received considerable attention as an attractive therapeutic target for the treatment of lung cancer or other inflammatory disease. A group of diversified thienopyridine derivatives exhibited a wide range of biological activity was used to investigate its structural requirements by using DFT and 3D-Quantitative structure activity relationship. Comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were established using the experimental activity of thienopyridine derivatives. The cross-validation coefficient (q2) values for CoMFA and CoMSIA are 0.671 and 0.647 respectively, were achieved, demonstrating high predictive capability of the model. The contour analysis indicate that presence of hydrophobic and electrostatic field is highly desirable for biological activity. The results indicate that substitution of hydrophobic group with electron withdrawing effect at R4 and R6 position have more possibility to increase the biological activity of thienopyridine derivatives. Subsequently molecular docking and DFT calculation were performed to assess the potency of the compounds.

Design, synthesis, characterization and biological evaluation of Thieno[2,3-b]pyridines-chitosan nanocomposites as drug delivery systems for colon targeting

Thieno[2,3-b]pyridine derivatives DATP_a-c have been synthesized based on Thorpe-Ziegler Cyclization. The reaction of arylidene malononitrile derivatives (I_a-c) with thiocyanoacetamide (II) in basic medium (piperidine) followed by alkylation using ethyl chloroacetate and finally, cyclization in sodium ethoxide yielded DATP_a-c. Thieno[2,3-b]pyridine-chitosan nanocomposites CS-DATP_a-c were prepared from the DATP_a-c and CS nanoparticles using sodium tripolyphosphate (TPP). CS-DATP_a-c nanocomposites were characterized using FTIR, TEM and XRD techniques and showed a relatively narrow size distribution of monodispersed nanoparticles with the average size of 14-78 nm. The in vitro release studies of CS-DAΤP_a-c nanocomposites were investigated and showed that the drug release rate is pH-dependent and the trend is as follows: basic > neutral > acidic. The faster release rate in basic medium effectively prolongs drug delivery in gastric pH. Additionally, the antibacterial investigation showed that DATP_a-c and CS-DATP_a-c nanocomposites exhibited antibacterial activity against both Gram-positive and Gram-negative bacteria but CS-DATP_a-c nanocomposites showed much higher antibacterial activity compared to the DATP_a-c, which in agreement with the particle size measurements as DATP_a-c are in the bulky structure whereas, CS-DATP_a-c are in the nanostructure. The results may have applications of drug design for colon targeting.

Discovery of Novel Adenosine Receptor Antagonists through a Combined Structure- and Ligand-Based Approach Followed by Molecular Dynamics Investigation of Ligand Binding Mode

An intense effort is made by pharmaceutical and academic research laboratories to identify and develop selective antagonists for each adenosine receptor (AR) subtype as potential clinical candidates for "soft" treatment of various diseases. Crystal structures of subtypes A_2A and A₁ARs offer exciting opportunities for structure-based drug design. In the first part of the present work, Maybridge HitFinder library of 14400 compounds was utilized to apply a combination of structure-based against the crystal structure of A_2AAR and ligand-based methodologies. The docking poses were rescored by CHARMM energy minimization and calculation of the desolvation energy using Poisson-Boltzmann equation electrostatics. Out of the eight selected and tested compounds, five were found positive hits (63% success). Although the project was initially focused on targeting A_2AAR, the identified antagonists exhibited low micromolar or micromolar affinity against A_2A/A₃, ARs, or A₃AR, respectively. Based on these results, 19 compounds characterized by novel chemotypes were purchased and tested. Sixteen of them were identified as AR antagonists with affinity toward combinations of the AR family isoforms (A_2A/A₃, A₁/A₃, A₁/A_2A/A₃, and A₃). The second part of this work involves the performance of hundreds of molecular dynamics (MD) simulations of complexes between the ARs and a total of 27 ligands to resolve the binding interactions of the active compounds, which were not achieved by docking calculations alone. This computational work allowed the prediction of stable and unstable complexes which agree with the experimental results of potent and inactive compounds, respectively. Of particular interest is that the 2-amino-thiophene-3-carboxamides, 3-acylamino-5-aryl-thiophene-2-carboxamides, and carbonyloxycarboximidamide derivatives were found to be selective and possess a micromolar to low micromolar affinity for the A₃ receptor.

Synthesis of some new Thieno[2,3-b]pyridines, Pyrimidino[4',5':4,5]thieno[2,3-b]pyridine and Pyridines Incorporating 5-Bromobenzofuran-2-yl Moiety

2-Sulfanyl-6-(2-thienyl)pyridine-3-carbonitrile, 1-Amino-6-(5-bromo-benzofuran-2-yl)-2-oxo-1,2-dihydro-pyridine-3-carbonitrile, thieno[2,3-b]pyridins, pyrimidino[4',5':4,5]thieno[2,3-b]pyridine, quinazoline and carbamate derivatives were synthesized from sodium 3-(5-bromobenzofuran-2-yl)-3-oxoprop-1-en-1-olate with. The newly synthesized compounds were elucidated by elemental analysis, spectral data, and alternative synthesis whenever possible and chemical transportation.

Synthesis and Characterization of Novel Thieno-Fused Bicyclic Compounds through New Enaminone Containing Thieno[2,3-b]pyridine Scaffold

New substituted thieno-fused bicyclic compounds named (1H-pyrazol-3-yl)thieno[2,3-b]pyridin-4(7H)-one derivatives (4a,b), 2-([1,2,4]triazolo[1,5-a]pyrimidin-7-yl)-3-methyl-7-phenylthieno[2,3-b]pyridin-4(7H)-one (5), phenylthieno[2,3-b]pyridin-4(7H)-one derivatives (6a–c,7a–c, and8), and 3-(3-methyl-4-oxo-7-phenyl-4,7-dihydrothieno[2,3-b]pyridin-2-yl)-3-oxopropyl 4-chlorobenzoate (9) were synthesized by reacting the new enaminone (3) with different reagents. The chemical structure of the new molecules was determined by means of different spectroscopic methods such as NMR, IR, MS spectrometry, and by CHN analyses. The molecular structure of the 1,1′-(3-methyl-5-(phenylamino)thiophene-2,4-diyl)diethanone (2) was successfully solved by X-ray single crystal.

Thieno[2,3-b]pyridines--a new class of multidrug resistance (MDR) modulators

To identify new potent multidrug resistance modulators, we have synthesized a series of novel thieno[2,3-b]pyridines and furo[2,3-b]pyridines, and examined their structure-activity relationships. All synthesized compounds were tested to determine BCRP1, P-gp, and MRP1 inhibitor activity, and most potent MDR modulators were also screened for their toxicity, cytotoxicity and Ca(2+) channel antagonist activity. Among these compounds, thieno[2,3-b]pyridine (6r) was found to exhibit a potent P-gp inhibitory action with EC50 = 0.3 ± 0.2 μM, MRP1 inhibitory action with EC50 = 1.1 ± 0.1 μM and BCRP1 inhibitory action with EC50 = 0.2 ± 0.05 μM and may represent suitable candidate for further pharmacological studies.

Synthesis, preliminary structure-activity relationships, and in vitro biological evaluation of 6-aryl-3-amino-thieno[2,3-b]pyridine derivatives as potential anti-inflammatory agents

In our previous study, a series of 6-aryl-3-amino-thieno[2,3-b]pyridine derivatives exhibited potent antiproliferative activities and an unique hepatocellular carcinoma (HCC)-specific anticancer activity was also observed. In further anti-inflammatory research, thienopyridine derivative 1a showed potent inhibition of nitric oxide (NO) production. So a series of thienopyridine analogues of 1a were synthesized and evaluated for anti-inflammatory activities. The structure-activity relationships (SARs) revealed that the most potent analogues 1f and 1o were identified as potent inhibitors of NO production with IC50 values of 3.30 and 3.24 μM, respectively. These results suggest that these 6-aryl-3-amino-thieno[2,3-b]pyridine derivatives might potentially constitute a novel class of anti-inflammatory agents, which require further studies.

Synthesis and pharmacological evaluation of thieno[2,3-b]pyridine derivatives as novel c-Src inhibitors

Among the recently investigated targets for cancer therapy is the c-Src non-receptor tyrosine kinase. Indeed research around deregulated activity of this enzyme has proven its role in tumor progression, while the beneficial effects of c-Src inhibitors in several pathological models has also been demonstrated. We report here the preparation and pharmacological profile of a novel series of c-Src inhibitors that was elaborated around a 3-amino-thieno[2,3-b]pyridine discovered during an HTS campaign. c-Src enzyme inhibition and c-Src inhibition were investigated in a series of related compounds derived from the initial hit. Molecular modeling as well as X-ray studies on one active compound allowed us to hypothesize on ligand orientation and interactions within the ATP hydrophobic pocket. Design and synthesis of structural analogs then led to new ligands possessing quite efficient enzymatic and c-Src inhibition. The structure-activity elements disclosed in this study shed light on the role played by substituents on the thienopyridine ring as well as the impact of other aromatic moieties in the molecule when interacting with the enzyme.

Discovery of imidazo[1,2-b]pyridazine derivatives as IKKbeta inhibitors. Part 1: Hit-to-lead study and structure-activity relationship

Imidazo[1,2-b]pyridazine derivatives from high-throughput screening were developed as IKKbeta inhibitors. By the optimization of the 3- and 6-position of imidazo[1,2-b]pyridazine scaffold, cell-free IKKbeta inhibitory activity and TNFalpha inhibitory activity in THP-1 cell increased. Also, these compounds showed high kinase selectivity. The structure-activity relationship was revealed and the interaction model of imidazo[1,2-b]pyridazine compounds with IKKbeta was constructed.

Synthesis of multicyclic pyridine and quinoline derivatives via intramolecular C-H bond functionalization

An efficient method is reported for the preparation of multicyclic pyridines and quinolines by a rhodium-catalyzed intramolecular C-H bond functionalization process. The method shows good scope for branched and unbranched alkyl substituents on the pyridine ring and at the R position of the tethered alkene group. Starting materials capable of undergoing olefin isomerization to provide terminal 1,1-disubstituted alkenes also proved to be effective substrates.

Synthesis and biological evaluation of tricyclic anilinopyrimidines as IKKbeta inhibitors

A series of tricyclic anilinopyrimidines were synthesized and evaluated as IKKbeta inhibitors. Several analogues, including tricyclic phenyl (10, 18a, 18c, 18d, and 18j) and thienyl (26 and 28) derivatives were shown to have good in vitro enzyme potency and excellent cellular activity. Pharmaceutical profiling of a select group of tricyclic compounds compared to the non-tricyclic analogues suggested that in some cases, the improved cellular activity may be due to increased clog P and permeability.