5-aryl-pyrazolo[3,4-b]pyridines: potent inhibitors of glycogen synthase kinase-3 (GSK-3)

Evolving significance of kinase inhibitors in the management of Alzheimer's disease

Alzheimer's disease is a neurodegenerative problem with progressive loss of memory and other cognitive function disorders resulting in the imbalance of neurotransmitter activity and signaling progression, which poses the need of the potential therapeutic target to improve the intracellular signaling cascade brought by kinases. Protein kinase plays a significant and multifaceted role in the treatment of Alzheimer's disease, by targeting pathological mechanisms like tau hyperphosphorylation, neuroinflammation, amyloid-beta production and synaptic dysfunction. In this review, we thoroughly explore the essential protein kinases involved in Alzheimer's disease, detailing their physiological roles, regulatory impacts, and the newest inhibitors and compounds that are progressing into clinical trials. All the findings of studies exhibited the promising role of kinase inhibitors in the management of Alzheimer's disease. However, it still poses the need of addressing current challenges and opportunities involved with this disorder for the future perspective of kinase inhibitors in the management of Alzheimer's disease. Further study includes the development of biomarkers, combination therapy, and next-generation kinase inhibitors with increased potency and selectivity for its future prospects.

Nanoparticles of a Pyrazolo-Pyridazine Derivative as Potential EGFR and CDK-2 Inhibitors: Design, Structure Determination, Anticancer Evaluation and In Silico Studies

The strategic planning of this study is based upon using the nanoformulation method to prepare nanoparticles 4-SLNs and 4-LPHNPs of the previously prepared 4,5-diphenyl-1H-pyrazolo[3,4-c]pyridazin-3-amine (4) after confirming its structure with single crystal X-ray analysis. These nanoparticles exhibited promising cytotoxic activity against HepG-2, HCT-116 and MCF-7 cancer cell lines in comparison with the reference doxorubicin and the original derivative 4. Moreover, their inhibitory assessment against EGFR and CDK-2/cyclin A2 displayed improved and more favorable impact than the parent 4 and the references. Detection of their influence upon cancer biomarkers revealed upregulation of Bax, p53 and caspase-3 levels and downregulation of Bcl-2 levels. The docking simulation demonstrated that the presence of the pyrazolo[3,4-c]pyridazin-3-amine scaffold is amenable to enclosure and binding well within EGFR and CDK-2 receptors through different hydrophilic interactions. The pharmacokinetic and physicochemical properties of target 4 were also assessed with ADME investigation, and the outcome indicated good drug-like characteristics.

1H-Pyrazolo[3,4-b]pyridines: Synthesis and Biomedical Applications

Pyrazolo[3,4-b]pyridines are a group of heterocyclic compounds presenting two possible tautomeric forms: the 1H- and 2H-isomers. More than 300,000 1H-pyrazolo[3,4-b]pyridines have been described which are included in more than 5500 references (2400 patents) up to date. This review will cover the analysis of the diversity of the substituents present at positions N1, C3, C4, C5, and C6, the synthetic methods used for their synthesis, starting from both a preformed pyrazole or pyridine, and the biomedical applications of such compounds.

Synthesis and Biological Activity Evaluation of Novel 5-Methyl-7-phenyl-3H-thiazolo[4,5-b]pyridin-2-ones

A series of 5-methyl-7-phenyl-3H-thiazolo[4,5-b]pyridin-2-ones has been designed, synthesized, and characterized by spectral data. Target compounds were screened for their antimicrobial activity against some pathogenic bacteria and fungi, and most of them showed moderate activity, especially compound 3g, which displayed the potent inhibitory effect against Pseudomonas aeruginosa and Escherichia coli with MIC value of 0.21 μM. The active thiazolopyridine derivatives 3c, 3f, and 3g were screened for their cytotoxicity effects on HaCat, Balb/c 3T3 cells using MTT assay, which revealed promising results. In silico assessment for compounds 3c, 3f, and 3g also revealed suitable drug-like parameters and ADME properties. The binding interactions of the most active compound 3g were performed through molecular docking against MurD and DNA gyrase, with binding energies and an inhibitory constant compared to the reference drug ciprofloxacin. The tested thiazolo[4,5-b]pyridines constitute an exciting background for the further development of new synthetic antimicrobial agents.

One-pot three-component synthesis of novel pyrazolo[3,4-b]pyridines as potent antileukemic agents

In the current study, we report on the development of novel series of pyrazolo[3,4-b]pyridine derivatives (8a-u, 11a-n, and 14a,b) as potential anticancer agents. The prepared pyrazolo[3,4-b]pyridines have been screened for their antitumor activity in vitro at NCI-DTP. Thereafter, compound 8a was qualified by NCI for full panel five-dose assay to assess its GI₅₀, TGI and LC₅₀ values. Compound 8a showed broad-spectrum anti-proliferative activities over the whole NCI panel, with outstanding growth inhibition full panel GI₅₀ (MG-MID) value equals 2.16 μM and subpanel GI₅₀ (MG-MID) range: 1.92-2.86 μM. Furthermore, pyrazolo[3,4-b]pyridines 8a, 8e-h, 8o, 8u, 11a, 11e, 11h, 11l and 14a-b were assayed for their antiproliferative effect against a panel of leukemia cell lines (K562, MV4-11, CEM, RS4;11, ML-2 and KOPN-8) where they possessed moderate to excellent anti-leukemic activity. Moreover, pyrazolo[3,4-b]pyridines 8o, 8u, 14a and 14b were further explored for their effect on cell cycle on RS4;11 cells, in which they dose-dependently increased populations of cells in G2/M phases. Finally we analyzed the changes of selected proteins (HOXA9, MEIS1, PARP, BcL-2 and McL-1) related to cell death and viability in RS4;11 cells via Western blotting. Collectively, the obtained results suggested pyrazolo[3,4-b]pyridines 8o, 8u, 14a and 14b as promising lead molecules for further optimization to develop more potent and efficient anticancer candidates.

Diphenyl pyrimidine exhibits protective effect on Staphylococcus aureus pneumonia in rat model by targeting NLRP3 expression

Pneumonia is one of the most frequent disorder induced by S. aureus infection and accounts for 13.3% of the all the infections caused by staphylococcus. In the present study effect of diphenyl pyrimidine was investigated against Staphylococcus aureus (S. aureus) induced pneumonia in the rat model. The results demonstrated that diphenyl pyrimidine treatment of the rats effectively prevented S. aureus induced increase in mortality in dose-dependent manner. Diphenyl pyrimidine treatment inhibited histopathological changes in S. aureus infected rat lungs. Treatment of the rats with 1.25, 2.5, 5 and 10 mg/kg doses of diphenyl pyrimidine significantly (P < 0.05) reversed S. aureus infection induced increase in interleukin (IL)-1β, IL-18 and tumor necrosis factor (TNF)-α levels. Treatment with 1.25, 2.5, 5 and 10 mg/kg doses of diphenyl pyrimidine significantly (P < 0.05) reversed S. aureus infection induced increase nucleotide-binding domain and leucine-rich repeat containing (NLR) protein (NLRP3), apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain (ASC) and caspase-1 protein expression in rat lungs in dose-dependent manner. The NLRP3, ASC and caspase-1 mRNA level in S. aureus infected rat pulmonary tissues was significantly (P < 0.05) reduced by diphenyl pyrimidine treatment in dose-dependent manner. Thus, diphenyl pyrimidine protects S. aureus-induced pneumonia through suppression of NLRP3 and inflammatory cytokine expression. Therefore, diphenyl pyrimidine can be of therapeutic importance for the treatment of S. aureus induced pneumonia.

Design, Synthesis, and Biological Evaluation of Novel 7H-[1,2,4]Triazolo[3,4-b][1,3,4]thiadiazine Inhibitors as Antitumor Agents

A series of novel anticancer hydrazinotriazolothiadiazine-based derivatives were designed based on the structure-activity relationship of the previously reported anticancer triazolothiadiazines. These derivatives were synthesized and biologically screened against full NCI-60 cancer cell lines revealing compound 5l with a potential antiproliferative effect. 5l was screened over 16 kinases to study its cytotoxic mechanism which showed to inhibit glycogen synthase kinase-3 β (GSK-3β) with IC₅₀ equal to 0.883 μM and 14-fold selectivity over CDK2. Also, 5l increased active caspase-3 levels, induced cell cycle arrest at the G2-M phase, and increased the percentage of Annexin V-fluorescein isothiocyanate-positive apoptotic cells in PC-3 prostate cancer-treated cells. Molecular docking and dynamics were performed to predict the binding mode of 5l in the GSK-3β ATP binding site. 5l can be utilized as a starting scaffold for developing potential GSK-3β inhibitors.

Crystal structure analysis of ethyl 3-(4-chloro-phen-yl)-1,6-dimethyl-4-methyl-sulfanyl-1H-pyrazolo[3,4-b]pyridine-5-carboxyl-ate

In the title compound, C18H18ClN3O2S, the dihedral angle between the fused pyrazole and pyridine rings is 3.81 (9)°. The benzene ring forms dihedral angles of 35.08 (10) and 36.26 (9)° with the pyrazole and pyridine rings, respectively. In the crystal, weak C-H⋯O hydrogen bonds connect mol-ecules along [100].

Discovery and optimization of novel pyridines as highly potent and selective glycogen synthase kinase 3 inhibitors

Glycogen synthase kinase-3 plays an essential role in multiple biochemical pathways in the cell, particularly in regards to energy regulation. As such, Glycogen synthase kinase-3 is an attractive target for pharmacological intervention in a variety of disease states, particularly non-insulin dependent diabetes mellitus. However, due to homology with other crucial kinases, such as the cyclin-dependent protein kinase CDC2, developing compounds that are both potent and selective is challenging. A novel series of derivatives of 5-nitro-N2-(2-(pyridine-2ylamino)ethyl)pyridine-2,6-diamine were synthesized and have been shown to potently inhibit glycogen synthase kinase-3 (GSK3). Potency in the low nanomolar range was obtained along with remarkable selectivity. The compounds activate glycogen synthase in insulin receptor-expressing CHO-IR cells and in primary rat hepatocytes, and have acceptable pharmacokinetics and pharmacodynamics to allow for oral dosing. The X-ray co-crystal structure of human GSK3-β in complex with compound 2 is reported and provides insights into the structural determinants of the series responsible for its potency and selectivity.

Na2S-promoted reduction of azides in water: synthesis of pyrazolopyridines in one pot and evaluation of antimicrobial activity

Reduction of various azides using Na2S has been accomplished in water, and, in situ, the resulting amines on reaction with various ketones lead to pyrazolo[3,4-b]pyridines in one pot. Thus, a number of new trifluoromethyl-substituted pyrazolo[3,4-b]pyridine compounds have been prepared and screened for antimicrobial activity against different Gram-positive and Gram-negative strains. A good number of compounds, 4a, 4b, 4d, 4f, 4i, 4k, 4l, 4m, 4r and 4s, were found to possess promising activity. Notably, Na2S on hydrolysis in water generates H2S and NaOH, which facilitate the reduction of azides followed by intramolecular cyclization leading to the title compounds. To the best of our knowledge, this is the first report of the synthesis of the title compounds in aqueous medium in a one-pot reaction.

Isoquinoline Alkaloids from Berberis vulgaris as Potential Lead Compounds for the Treatment of Alzheimer's Disease

Three new alkaloids, bersavine (3), muraricine (4), and berbostrejdine (8), together with seven known isoquinoline alkaloids (1-2, 5-7, 9, and 10) were isolated from an alkaloidal extract of the root bark of Berberis vulgaris. The structures of the isolated compounds were determined by spectroscopic methods, including 1D and 2D NMR techniques, HRMS, and optical rotation, and by comparison of the obtained data with those in the literature. The NMR data of berbamine (5), aromoline (6), and obamegine (7) were completely assigned employing 2D NMR experiments. Alkaloids isolated in sufficient amounts were evaluated for their in vitro acetylcholinesterase, butyrylcholinesterase (BuChE), prolyl oligopeptidase, and glycogen synthase kinase-3β inhibitory activities. Selected compounds were studied for their ability to permeate through the blood-brain barrier. Significant human BuChE ( hBuChE) inhibitory activity was demonstrated by 6 (IC₅₀ = 0.82 ± 0.10 μM). The in vitro data were further supported by computational analysis that showed the accommodation of 6 in the active site of hBuChE.

Computer-aided molecular design of pyrazolotriazines targeting glycogen synthase kinase 3

Numerous studies have highlighted the implications of the glycogen synthase kinase 3 (GSK-3) in several processes associated with Alzheimer's disease (AD). Therefore, GSK-3 has become a crucial therapeutic target for the treatment of this neurodegenerative disorder. Hereby, we report the design and multistep synthesis of ethyl 4-oxo-pyrazolo[4,3-d][1-3]triazine-7-carboxylates and their biological evaluation as GSK-3 inhibitors. Molecular modelling studies allow us to develop this new scaffold optimising the chemical structure. Potential binding mode determination in the enzyme and the analysis of the key features in the catalytic site are also described. Furthermore, the ability of pyrazolotriazinones to cross the blood-brain barrier (BBB) was evaluated by passive diffusion and those who showed great GSK-3 inhibition and permeation to the central nervous system (CNS) showed neuroprotective properties against tau hyperphosphorylation in a cell-based model. These new brain permeable pyrazolotriazinones may be used for key in vivo studies and may be considered as new leads for further optimisation for the treatment of AD.

Amaryllidaceae Alkaloids as Potential Glycogen Synthase Kinase-3β Inhibitors

Glycogen synthase kinase-3β (GSK-3β) is a multifunctional serine/threonine protein kinase that was originally identified as an enzyme involved in the control of glycogen metabolism. It plays a key role in diverse physiological processes including metabolism, the cell cycle, and gene expression by regulating a wide variety of well-known substances like glycogen synthase, tau-protein, and β-catenin. Recent studies have identified GSK-3β as a potential therapeutic target in Alzheimer´s disease, bipolar disorder, stroke, more than 15 types of cancer, and diabetes. GSK-3β is one of the most attractive targets for medicinal chemists in the discovery, design, and synthesis of new selective potent inhibitors. In the current study, twenty-eight Amaryllidaceae alkaloids of various structural types were studied for their potency to inhibit GSK-3β. Promising results have been demonstrated by alkaloids of the homolycorine-{9-O-demethylhomolycorine (IC₅₀ = 30.00 ± 0.71 µM), masonine (IC₅₀ = 27.81 ± 0.01 μM)}, and lycorine-types {caranine (IC₅₀ = 30.75 ± 0.04 μM)}.

Synthesis of 3,6-diaryl-1H-pyrazolo[3,4-b]pyridines via one-pot sequential Suzuki–Miyaura coupling

A practical synthesis of diarylpyrazolo[3,4-b]pyridine derivatives by a combination of chemoselective Suzuki–Miyaura cross-coupling reactions was developed. The sequential arylation strategy can be performed in a one-pot manner without much loss of efficiency when compared to the corresponding stepwise synthesis. These conditions are applicable to the coupling of a wide variety of aryl and heteroaryl-boronic acids with pyrazolo[3,4-b]pyridines with high selectivity of the C3 over the C6 position, thus enabling the rapid construction of a diverse array of medicinally important diarylpyrazolo[3,4-b]pyridines.

An efficient method to produce diarylpyrazolo[3,4-b]pyridines derivatives via combination of chemoselective Suzuki–Miyaura cross-coupling reactions has been developed.

Glycogen synthase kinase-3 and its inhibitors: Potential target for various therapeutic conditions

Glycogen Synthase Kinase-3 (GSK-3) is a serine/threonine kinase which is ubiquitously expressed and is regarded as a regulator for various cellular events and signalling pathways. It exists in two isoforms, GSK-3α and GSK-3β and can phosphorylate a wide range of substrates. Aberrancy in the GSK-3 activity can lead to various diseases like Alzheimer's, diabetes, cancer, neurodegeneration etc., rendering it an attractive target to develop potent and specific inhibitors. The present review focuses on the recent developments in the area of GSK-3 inhibitors and also enlightens its therapeutic applicability in various disease conditions.

Identification of lead small molecule inhibitors of glycogen synthase kinase-3 beta using a fragment-linking strategy

Glycogen synthase kinase-3 beta (GSK3β) kinase serves as a promising therapeutic target for the treatment of various human diseases, such as diabetes, obesity, and Alzheimer's disease. In this study, we report lead GSK3β inhibitors identified using a fragment-linking strategy. Through the systematic exploration, a six-atom chain unit bearing the rigid double bond was found to be a suitable linker connecting two fragments, which enables favorable contacts with backbone groups of residues in the pockets. As a consequence, potent GSK3β inhibitor 9i was found with IC₅₀ values of 19nM. The binding mode analysis indicates that the activities of the inhibitors appear to be achieved by the establishment of multiple hydrogen bonds and hydrophobic interactions in the ATP-binding site of GSK3β. The good biochemical potencies and structural uniqueness of the inhibitors support consideration in the further study to optimize the biological activity.

Synthesis of novel ethyl 2,4-disubstituted 8-(trifluoromethyl)pyrido[2',3':3,4]pyrazolo[1,5-a]pyrimidine-9-carboxylate derivatives as promising anticancer agents

A series of novel pyrido[2',3':3,4] pyrazolo[1,5-a]pyrimidine derivatives 6-9 were prepared in single step starting from 3-amino-6-(trifluoromethyl)-1H-pyrazolo[3,4-b]pyridine-5-carboxylate 5 on reaction with symmetrical and unsymmetrical aliphatic and aromatic 1,3-diketones/α,β unsaturated ketones/α,β unsaturated keto ethers under conventional method. All the final compounds 6a-c, 8a-b and 9a-l were screened for anticancer activity against five human cancer cell lines such as PC-3 (CRL-1435), MDA-MB-231 (HTB-26), Hep G2 (HB-8065), HeLa (CCL-2) and normal HUVEC (CRL-1730). Compounds 8a, 9f and 9k which showed promising anticancer activity have been identified. Further, the promising compounds (8a and 9f) were able to inhibit the human topoisomerase I (TopI) activity similar to that of camptothecin.

Synthesis of novel hydrazone and azole functionalized pyrazolo[3,4-b]pyridine derivatives as promising anticancer agents

A series of novel pyrazolo[3,4-b]pyridine based target compounds were synthesized starting from the key intermediate ethyl 2-(3-amino-6-(trifluoromethyl)-1H-pyrazolo[3,4-b]pyridin-1-yl)acetate 5 on reaction with hydrazine hydrate followed by reaction with different aldehydes, acid chlorides and isothiocyanates to form hydrazones 7, oxadiazoles 8, 1,2,4 triazoles 10 and thiadiazoles 11 respectively in high yield. All the final compounds were screened for anticancer activity against four human cancer cell lines. Among them, 1,2,4 triazole derivatives showed promising activity and compound 10d is identified as a lead molecule.

Copper(ii) oxide nanoparticles as a highly active and reusable heterogeneous catalyst for the construction of phenyl-1H-pyrazolo[3,4-b]pyridine derivatives under solvent-free conditions

We developed a simple and efficient method for the one-pot synthesis of phenyl-1H-pyrazolo[3,4-b]pyridine derivatives in the presence of CuO NPs under solvent-free conditions with higher yields and shorter reaction times.

Pivotal role of glycogen synthase kinase-3: A therapeutic target for Alzheimer's disease

Neurodegenerative diseases are among the most challenging diseases with poorly known mechanism of cause and paucity of complete cure. Out of all the neurodegenerative diseases, Alzheimer's disease is the most devastating and loosening of thinking and judging ability disease that occurs in the old age people. Many hypotheses came forth in order to explain its causes. In this review, we have enlightened Glycogen Synthase Kinase-3 which has been considered as a concrete cause for Alzheimer's disease. Plaques and Tangles (abnormal structures) are the basic suspects in damaging and killing of nerve cells wherein Glycogen Synthase Kinase-3 has a key role in the formation of these fatal accumulations. Various Glycogen Synthase Kinase-3 inhibitors have been reported to reduce the amount of amyloid-beta as well as the tau hyperphosphorylation in both neuronal and nonneuronal cells. Additionally, Glycogen Synthase Kinase-3 inhibitors have been reported to enhance the adult hippocampal neurogenesis in vivo as well as in vitro. Keeping the chemotype of the reported Glycogen Synthase Kinase-3 inhibitors in consideration, they may be grouped into natural inhibitors, inorganic metal ions, organo-synthetic, and peptide like inhibitors. On the basis of their mode of binding to the constituent enzyme, they may also be grouped as ATP, nonATP, and allosteric binding sites competitive inhibitors. ATP competitive inhibitors were known earlier inhibitors but they lack efficient selectivity. This led to find the new ways for the enzyme inhibition.

Four-component bicyclization approaches to skeletally diverse pyrazolo[3,4-b]pyridine derivatives

A novel four-component bicyclization strategy has been established, allowing a flexible and practical approach to 37 examples of multicyclic pyrazolo[3,4-b]pyridines from low-cost and readily accessible arylglyoxals, pyrazol-5-amines, aromatic amines, 4-hydroxy-6-methyl-2H-pyran-2-one, and cyclohexane-1,3-diones. The polysubstituted cyclopenta[d]pyrazolo[3,4-b]pyridines were stereoselectively synthesized through a microwave-assisted special [3+2+1]/[3+2] bicyclization with good control of the spatial configuration of exocyclic double bonds. The novel [3+2+1]/[2+2+1] bicyclization resulted in 17 examples of unreported pyrazolo[3,4-b]pyrrolo[4,3,2-de]quinolones. Reasonable mechanisms for forming two new types of multicyclic pyrazolo[3,4-b]pyridines are also proposed.

Quantitative Structure-Activity Relationship Analysis and a Combined Ligand-Based/Structure-Based Virtual Screening Study for Glycogen Synthase Kinase-3

Glycogen synthase kinase-3 (GSK-3) is a multifunctional serine/threonine protein kinase which regulates a wide range of cellular processes, involving various signalling pathways. GSK-3β has emerged as an important therapeutic target for diabetes and Alzheimer's disease. To identify structurally novel GSK-3β inhibitors, we performed virtual screening by implementing a combined ligand-based/structure-based approach, which included quantitative structure-activity relationship (QSAR) analysis and docking prediction. To integrate and analyze complex data sets from multiple experimental sources, we drafted and validated a hierarchical QSAR method, which adopts a two-level structure to take data heterogeneity into account. A collection of 728 GSK-3 inhibitors with diverse structural scaffolds was obtained from published papers that used different experimental assay protocols. Support vector machines and random forests were implemented with wrapper-based feature selection algorithms to construct predictive learning models. The best models for each single group of compounds were then used to build the final hierarchical QSAR model, with an overall R(2) of 0.752 for the 141 compounds in the test set. The compounds obtained from the virtual screening experiment were tested for GSK-3β inhibition. The bioassay results confirmed that 2 hit compounds are indeed GSK-3β inhibitors exhibiting sub-micromolar inhibitory activity, and therefore validated our combined ligand-based/structure-based approach as effective for virtual screening experiments.

Pharmacophore Modeling, Ensemble Docking, Virtual Screening, and Biological Evaluation on Glycogen Synthase Kinase-3β

Glycogen synthase kinase-3 (GSK-3) is a multifunctional serine/threonine protein kinase which is engaged in a variety of signaling pathways, regulating a wide range of cellular processes. GSK-3β, also known as tau protein kinase I (TPK-I), is one of the most important kinases implicated in the hyperphosphorylation of tau that leads to neurodegenerative diseases. Hence, GSK-3β has emerged as an important therapeutic target. To identify compounds that are structurally novel and diverse compared to previously reported ATP-competitive GSK-3β inhibitors, we performed virtual screening by implementing a mixed ligand/structure-based approach, which included pharmacophore modeling, diversity analysis, and ensemble docking. The sensitivities of different docking protocols to induced-fit effects were explored. An enrichment study was employed to verify the robustness of ensemble docking, using 13 X-ray structures of GSK-3β, compared to individual docking in terms of retrieving active compounds from a decoy dataset. A total of 24 structurally diverse compounds obtained from the virtual screening underwent biological validation. The bioassay results showed that 15 out of the 24 hit compounds are indeed GSK-3β inhibitors, and among them, one compound exhibiting sub-micromolar inhibitory activity is a reasonable starting point for further optimization.

Formal [4+2] annulation of enaminones and cyanomethyl sulfur ylide: one-pot access to polysubstituted pyridin-2(1H)-ones

One-pot synthesis of polysubstituted pyridin-2(1H)-ones by formal [4+2] annulation of enaminones and cyanomethyl sulfur ylide is described involving sequential nucleophilic vinylic substitution, intramolecular nucleophilic cyclization and dealkylation reactions.

A Casein kinase 1/Checkpoint kinase 1 pyrazolo-pyridine protein kinase inhibitor as novel activator of the p53 pathway

Reactivation of the wild-type p53 pathway is one key goal aimed at developing targeted therapeutics in the cancer research field. Although most p53 protein kinases form 'p53-activating' signals, there are few kinases whose action can contribute to the inhibition of p53, as Casein kinase 1 (CK1) and Checkpoint kinase 1 (CHK1). Here we report on a pyrazolo-pyridine analogue showing activity against both CK1 and CHK1 kinases that lead to p53 pathway stabilisation, thus having pharmacological similarities to the p53-activator Nutlin-3. These data demonstrate the emerging potential utility of multivalent kinase inhibitors.

Synthesis and biological evaluation of novel alkyl amide functionalized trifluoromethyl substituted pyrazolo[3,4-b]pyridine derivatives as potential anticancer agents

A series of novel alkyl amide functionalized trifluoromethyl substituted pyrazolo[3,4-b]pyridine derivatives 5, 6 and 7 were prepared starting from 6-phenyl-4-(trifluoromethyl)-1H-pyrazolo[3,4-b]pyridin-3-amine 3 via selective N-alkylation, followed by reaction with different primary aliphatic amines, cyclic secondary amines or l-amino acids under different set of conditions. All the synthesized compounds 5, 6 and 7 were screened for anticancer activity against four cancer cell lines such as A549-Lung cancer (CCL-185), MCF7-Breast cancer (HTB-22), DU145-Prostate cancer (HTB-81) and HeLa-Cervical cancer (CCL-2). The compounds 5i and 6e are found to have promising bioactivity at micro molar concentration.

Identification of Autophosphorylation Inhibitors of the Inositol-Requiring Enzyme 1 Alpha (IRE1α) by High-Throughput Screening Using a DELFIA Assay

Inositol-requiring enzyme 1 alpha (IRE1α) is a transmembrane sensor protein with both kinase and ribonuclease activity, which plays a crucial role in the unfolded protein response (UPR). Protein misfolding in the endoplasmic reticulum (ER) lumen triggers dimerization and subsequent trans-autophosphorylation of IRE1α. This leads to the activation of its endoribonuclease (RNase) domain and splicing of the mRNA of the transcriptional activator XBP1, ultimately generating an active XBP1 (XBP1s) implicated in multiple myeloma survival. Previously, we have identified human IRE1α as a target for the development of kinase inhibitors that could modulate the UPR in human cells, which has particular relevance for multiple myeloma and other secretory malignancies. Here we describe the development and validation of a 384-well high-throughput screening assay using DELFIA technology that is specific for IRE1α autophosphorylation. Using this format, a focused library of 2312 potential kinase inhibitors was screened, and several novel IRE1α kinase inhibitor scaffolds were identified that could potentially be developed toward new therapies to treat multiple myeloma.

Small-Molecule Inhibitors of GSK-3: Structural Insights and Their Application to Alzheimer's Disease Models

The world health organization (WHO) estimated that 18 million people are struck by Alzheimer's disease (AD). The USA, France, Germany, and other countries launched major programmes targeting the identification of risk factors, the improvement of caretaking, and fundamental research aiming to postpone the onset of AD. The glycogen synthase kinase 3 (GSK-3) is implicated in multiple cellular processes and has been linked to the pathogenesis of several diseases including diabetes mellitus, cancer, and AD. Inhibition of GSK-3 leads to neuroprotective effects, decreased β-amyloid production, and a reduction in tau hyperphosphorylation, which are all associated with AD. Various classes of small molecule GSK-3 inhibitors have been published in patents and original publications. Herein, we present a comprehensive summary of small molecules reported to interact with GSK-3. We illustrate the interactions of the inhibitors with the active site. Furthermore, we refer to the biological characterisation in terms of activity and selectivity for GSK-3, elucidate in vivo studies and pre-/clinical trials.

Construction of pyrazolo[3,4-b]pyridines and pyrazolo[4,3-c]pyridines by ring closure of 3-acylpyridine N-oxide tosylhydrazones

3-Acylpyridine N-oxide tosylhydrazones give good overall yields of a mixture of pyrazolo[3,4-b]pyridines and pyrazolo[4,3-c]pyridines when treated with an electrophilic additive and an amine base. (Z)-Hydrazones cyclize readily, while (E)-hydrazones fail to react under the reported conditions. The reaction takes place at room temperature, and moderate regiocontrol over the cyclization can be achieved by varying the electrophile/solvent combination.

Ultrasound assisted one-pot, three-components synthesis of pyrimido[1,2-a]benzimidazoles and pyrazolo[3,4-b]pyridines: A new access via phenylsulfone synthon

A simple, facile, efficient and three-components procedure for the synthesis of pyrimido[1,2-a]benzimidazoles and pyrazolo[3,4-b]pyridines utilizing phenylsulfone synthon, under ultrasonic irradiation was developed.