Identification and structure–activity relationship of 8-hydroxy-quinoline-7-carboxylic acid derivatives as inhibitors of Pim-1 kinase

Cyanopyridinone- and Cyanopyridine-Based Cancer Cell Pim-1 Inhibitors: Design, Synthesis, Radiolabeling, Biodistribution, and Molecular Modeling Simulation

In this study, two new series of 3-cyanopyridinones (3a-e) and 3-cyanopyridines (4a-e) were synthesized and evaluated for their cytotoxicity and Pim-1 kinase inhibitory activity adopting 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay and in vitro Pim-1 kinase inhibition assay, respectively. Most of the tested compounds revealed promising cytotoxicity against HepG-2, HCT-116, MCF-7, and PC-3 cell lines. Among them, compounds 4c and 4d showed more potent cytotoxicity against the HePG2 cell line with IC₅₀ = 8.02 ± 0.38 and 6.95 ± 0.34 μM, respectively, than that of the reference 5-FU (IC₅₀ = 9.42 ± 0.46 μM). Moreover, compound 4c was more potent against HCT-116 (IC₅₀ = 7.15 ± 0.35 μM) than 5-FU (IC₅₀ = 8.01 ± 0.39 μM), while compound 4d with IC₅₀ = 8.35 ± 0.42 μM displayed comparable activity to that of the reference drug. Furthermore, high cytotoxic activity was manifested by compounds 4c and 4d against MCF-7 and PC3 cell lines. Our results have also indicated that compounds 4b, 4c, and 4d elicited remarkable inhibition of Pim-1 kinase; 4b and 4c showed equipotent inhibitory activity to that of the reference quercetagetin. Meanwhile, 4d displayed IC₅₀ = 0.46 ± 0.02 μM, showed the best inhibitory activity among the tested compounds, and was more potent than quercetagetin (IC₅₀ = 0.56 ± 0.03 μM). For optimization of the results, docking study of the most potent compounds 4c and 4d in the Pim-1 kinase active site was carried out and compared with both quercetagetin and the reported Pim-1 inhibitor A (VRV), and the results were consistent with those of the biological study. Consequently, compounds 4c and 4d are worthy of further investigations toward the discovery of Pim-1 kinase inhibitors as drug candidates for cancer therapy. Compound 4b was successfully radiolabeled with radioiodine-131, and its biodistribution in Ehrlich ascites carcinoma (EAC)-bearing mice showed more observable uptake in tumor sites, and hence, it can be introduced as a new radiolabeled agent for tumor imaging and therapy.

Photoinduced electron transfer (PeT) based fluorescent probes for cellular imaging and disease therapy

Typical PeT-based fluorescent probes are multi-component systems where a fluorophore is connected to a recognition/activating group by an unconjugated linker. PeT-based fluorescent probes are powerful tools for cell imaging and disease diagnosis due to their low fluorescence background and significant fluorescence enhancement towards the target. This review provides research progress towards PeT-based fluorescent probes that target cell polarity, pH and biological species (reactive oxygen species, biothiols, biomacromolecules, etc.) over the last five years. In particular, we emphasise the molecular design strategies, mechanisms, and application of these probes. As such, this review aims to provide guidance and to enable researchers to develop new and improved PeT-based fluorescent probes, as well as promoting the use of PeT-based systems for sensing, imaging, and disease therapy.

Styrylquinolines Derivatives: SAR study and Synthetic Approaches

Abstract:

In the present-day scenario, heterocyclic derivatives have revealed the primary function of various medicinal agents precious for humanity. Out of a diverse range of heterocycles, Styrylquinolines scaffolds have been proved to play an essential role in a broad range of biological activities, includinganti-HIV-1, antimicrobial, anti-inflammatory, anti-Alzheimer activity with antiproliferative effects on tumor cell lines. Due to the immense pharmacological importance, distinct synthetic methods have been executed to attain new drug entities from Styrylquinolines. Various schemes for synthesizing Styrylquinolines derivatives like one-pot, ultrasound-promoted heterogeneous acid-catalysed, microwave-assisted, solvent-free, and green synthesis were discussed in the present review. Some products of Styrylquinolines are in clinical trials, and patents are also granted for the novel synthesis of Styrylquinolines. According to the structure-activity relationship, replacement at the R-7 and R-8 positions is required for various activities. In this review, recent synthetic approaches in the medicinal chemistry of Styrylquinolines and potent Styrylquinolines derivatives based on structural activity relationships (SAR) are outlined. Moreover, their primary methods and modifications are also discussed.

Spirocyclic derivatives as antioxidants: a review

In recent years, spiro compounds have attracted significant interest in medicinal chemistry due to their numerous biological activities attributed primarily to their versatility and structural similarity to important pharmacophore centers. Currently, the development of drugs with potential antioxidant activities is of great importance since numerous investigations have shown that oxidative stress is involved in the development and progression of numerous diseases such as cancer, senile cataracts, kidney failure, diabetes, high blood pressure, cirrhosis, and neurodegenerative diseases, among others. This article provides an overview of the synthesis and various antioxidant activities found in naturally occurring and synthetic spiro compounds. Among the antioxidant activities reviewed are DPPH, ABTS, FRAP, anti-LPO, superoxide, xanthine oxidase, peroxide, hydroxyl, and nitric oxide tests, among others. Molecules that presented best results for these tests were spiro compounds G14, C12, D41, C18, C15, D5, D11, E1, and C14. In general, most active compounds are characterized for having at least one oxygen atom; an important number of them (around 35%) are phenolic compounds, and in molecules where this functional group was absent, aryl ethers and nitrogen-containing functional groups such as amine and amides could be found. Recent advances in the antioxidant activity profiles of spiro compounds have shown that they have a significant position in discovering drugs with potential antioxidant activities.

Discovery of SARxxxx92, a pan-PIM kinase inhibitor, efficacious in a KG1 tumor model

N-substituted azaindoles were discovered as potent pan-PIM inhibitors. Lead optimization, guided by structure and focused on physico-chemical properties allowed us to solve inherent hERG and permeability liabilities, and provided compound 27, which subsequently impacted KG-1 tumor growth in a mouse model.

Understanding PIM-1 kinase inhibitor interactions with free energy simulation

The proviral integration site of the Moloney leukemia virus (PIM) family includes three homologous members. PIM-1 kinase is an important target in effective therapeutic interventions of lymphomas, prostate cancer and leukemia. In the current work, we performed free energy calculations to calculate the binding affinities of several inhibitors targeting this protein. The alchemical method with integration and perturbation-based estimators and the end-point methods were compared. The computational results indicated that the alchemical method can accurately predict the binding affinities, while the end-point methods give relatively unreliable predictions. Decomposing the free energy difference into enthalpic and entropic components with MBAR reweighting enabled us to investigate the detailed thermodynamic parameters with which the entropy-enthalpy compensation in this protein-ligand binding case is identified. We then studied the conformational ensemble, and the important protein-ligand interactions were identified. The current work sheds light on the understanding of the PIM-1-kinase-inhibitor interactions at the atomic level and will be useful in the further development of potential drugs.

Discovery of N-substituted 7-azaindoles as Pan-PIM kinases inhibitors - Lead optimization - Part III

N-substituted azaindoles were discovered as promising pan-PIM inhibitors. Lead optimization is described en route toward the identification of a clinical candidate. Modulation of physico-chemical properties allowed to solve inherent hERG and permeability liabilities. Compound 17 showed tumor growth inhibition in a KG1 tumor-bearing mouse model.

Synthesis, biological evaluations and computational studies of N-(3-(-2-(7-Chloroquinolin-2-yl)vinyl) benzylidene)anilines as fungal biofilm inhibitors

In the present investigation, new chloroquinoline derivatives bearing vinyl benzylidene aniline substituents at 2nd position were synthesized and screed for biofilm inhibitory, antifungal and antibacterial activity. The result of biofilm inhibition of C. albicans suggested that compounds 5j (IC₅₀ value = 51.2 μM) and 5a (IC₅₀ value = 66.2 μM) possess promising antibiofilm inhibition when compared with the standard antifungal drug fluconazole (IC₅₀ = 40.0 μM). Two compounds 5a (MIC = 94.2 μg/mL) and 5f (MIC = 98.8 μg/mL) also exhibited good antifungal activity comparable to standard drug fluconazole (MIC = 50.0 μg/mL). The antibacterial screening against four strains of bacteria viz. E. coli, P. aeruginosa, B. subtilis, and S. aureus suggested their potential antibacterial activity and especially all the compounds except 5g were found more active than the standard drug ciprofloxacin against B. subtilis. To further gain insights into the possible mechanism of these compounds in biofilm inhibition through the agglutinin like protein (Als), molecular docking and molecular dynamics simulation studies were carried out. Molecular modeling studies suggested the clear role in inhibition of this protein and the resulting biofilm inhibitory activity.

Dual-Specificity Tyrosine Phosphorylation-Regulated Kinase 1A (DYRK1A) Inhibitors as Potential Therapeutics

Dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A) is a member of an evolutionarily conserved family of protein kinases that belongs to the CMGC group of kinases. DYRK1A, encoded by a gene located in the human chromosome 21q22.2 region, has attracted attention due to its association with both neuropathological phenotypes and cancer susceptibility in patients with Down syndrome (DS). Inhibition of DYRK1A attenuates cognitive dysfunctions in animal models for both DS and Alzheimer's disease (AD). Furthermore, DYRK1A has been studied as a potential cancer therapeutic target because of its role in the regulation of cell cycle progression by affecting both tumor suppressors and oncogenes. Consequently, selective synthetic inhibitors have been developed to determine the role of DYRK1A in various human diseases. Our perspective includes a comprehensive review of potent and selective DYRK1A inhibitors and their forthcoming therapeutic applications.

First synthesis of novel 2,4-bis((E)-styryl)quinoline-3-carboxylate derivatives and their antitumor activity

A simple and flexible synthesis of a new series of 2,4-bis((E)-styryl)quinoline-3-carboxylates (3a-t) has been achieved for the first time in good yields via successive Arbuzov/Horner-Wadsworth-Emmons (HWE) reaction in one-pot using the newly-synthesized ethyl 4-(bromomethyl)-2-(chloromethyl)quinoline-3-carboxylate as the substrate. Our synthetic protocol is as attractive and powerful as it is simple, tolerates a wide range of substituents, and does not involve the use of expensive reagents or catalysts. These title compounds belong to a new class of quinoline derivatives and their antitumor activity was assessed on human cancer cell lines (A549, HT29 and T24). The MTT assay showed compounds 3h, 3k and 3t had significant inhibitory activity with IC₅₀ values of 1.53, 1.38 and 2.36 μM against A549 and 1.50, 0.77 and 0.97 μM against HT29, respectively, much better than the reference cisplatin.

Syntheses, Crystal Structures, and Antitumor Activities of Copper(II) and Nickel(II) Complexes with 2-((2-(Pyridin-2-yl)hydrazono)methyl)quinolin-8-ol

Two transition metal complexes with 2-((2-(pyridin-2-yl)hydrazono)methyl)quinolin-8-ol (L), [Cu(L)Cl₂]₂ (1) and [Ni(L)Cl₂]·CH₂Cl₂ (2), were synthesized and fully characterized. Complex 1 exhibited high in vitro antitumor activity against SK-OV-3, MGC80-3 and HeLa cells with IC50 values of 3.69 ± 0.16, 2.60 ± 0.17, and 3.62 ± 0.12 μM, respectively. In addition, complex 1 caused cell arrest in the S phase, which led to the down-regulation of Cdc25 A, Cyclin B, Cyclin A, and CDK2, and the up-regulation of p27, p21, and p53 proteins in MGC80-3 cells. Complex 1 induced MGC80-3 cell apoptosis via a mitochondrial dysfunction pathway, as shown by the significantly decreased level of bcl-2 protein and the loss of Δψ, as well as increased levels of reactive oxygen species (ROS), intracellular Ca2+, cytochrome C, apaf-1, caspase-3, and caspase-9 proteins in MGC80-3 cells.

Highly Selective Red-Emitting Fluorescent Probe for Imaging Cancer Cells in Situ by Targeting Pim-1 Kinase

Based on the fact that enzyme-targeting probes are highly sensitive and selective, a novel red-emitting probe (NB-BF) for Pim-1 kinase including three parts, fluorophore (NB), linker, and inhibitor (BF), has been designed for cancer optical imaging. In its free state, NB-BF is folded and the fluorescence quenched by PET between fluorophore and inhibitor both in PBS buffer and in normal cells. Significantly, it emitted strong red fluorescence in Pim-1 overexpressed cancer cells. The specificity of NB-BF for Pim-1 kinase was directly demonstrated by gene silencing analysis. Furthermore, it is the first time to know where Pim-1 kinase mainly distributes at mitochondria with Pearson's correlation factor (R_r) of 0.965 and to provide a fluorescent tool to verify the function of the Pim-1 kinase. More importantly, NB-BF was applied in tissue imaging and preferentially labeled tumors in vivo.

A facile synthesis of (E)-2-(aryl/hetaryl)vinyl-4-phenylquinoline-3-carboxylic acids

New synthetic approach to (

Discovery of N-substituted 7-azaindoles as Pan-PIM kinase inhibitors - Lead series identification - Part II

N-Substituted azaindoles have been discovered as pan-PIM kinase inhibitors. Initial SAR, early ADME and PK/PD data of a series of compounds is described and led to the identification of promising pan-PIM inhibitors which validated our interest in the 7-azaindole scaffold and led us to pursue the identification of a clinical candidate.

Novel amalgamation of phthalazine-quinolines as biofilm inhibitors: One-pot synthesis, biological evaluation and in silico ADME prediction with favorable metabolic fate

A facile and highly efficient one-pot synthesis of phthalazine-quinoline derivatives is reported via four component reaction of phthalic anhydride, hydrazine hydrate, 5,5-dimethyl 1,3 cyclohexanedione and various quinoline aldehydes using PrxCoFe2-xO4 (x=0.1) nanoparticles as a catalyst. The synthesized compounds have been evaluated for anti-biofilm activity against Pseudomonas aeruginosa and Candida albicans. The compounds 12a (IC50=30.0μM) and 12f (IC50=34.5μM) had shown promising anti-biofilm activity against P. aeruginosa and C. albicans, respectively, when compared with standards without affecting the growth of cells (and thus behave as anti-quorum sensing agents). Compounds 12a (MIC=45.0μg/mL) and 12f (MIC=57.5μg/mL) showed significant potent antimicrobial activity against P. aeruginosa and C. albicans, respectively. Thus, the active derivatives were not only potent biofilm inhibitors but also efficient antimicrobial agents. In silico ADME and metabolic site prediction studies were also held out to set an effective lead candidate for the future antimicrobial drug discovery initiatives.

Identification of novel inhibitors for Pim-1 kinase using pharmacophore modeling based on a novel method for selecting pharmacophore generation subsets

Targeting Proviral integration-site of murine Moloney leukemia virus 1 kinase, hereafter called Pim-1 kinase, is a promising strategy for treating different kinds of human cancer. Headed for this a total list of 328 formerly reported Pim-1 kinase inhibitors has been explored and divided based on the pharmacophoric features of the most active molecules into 10 subsets projected to represent potential active binding manners accessible to ligands within the binding pocket of Pim-1 kinase. Discovery Studio 4.1 (DS 4.1) was employed to detect potential pharmacophoric active binding manners anticipated by Pim-1 Kinase inhibitors. The pharmacophoric models were then allowed to compete within Quantitative Structure Activity Relationship (QSAR) framework with other 2D descriptors. Accordingly Genetic algorithm and multiple linear regression investigation were engaged to find the finest QSAR equation that has the best predictive power r262(2) = 0.70, F = 119.14, rLOO(2) = 0.693, rPRESS(2) against 66 external test inhibitors = 0.71 q(2) = 0.55. Three different pharmacophores appeared in the successful QSAR equation this represents three different binding modes for inhibitors within the Pim-1 kinase binding pocket. Pharmacophoric models were later used to screen compounds within the National Cancer Institute database. Several low micromolar Pim-1 Kinase inhibitors were captured. The most potent hits show IC50 values of 0.77 and 1.03 µM. Also, upon analyzing the successful QSAR Equation we found that some polycyclic aromatic electron-rich structures namely 6-Chloro-2-methoxy-acridine can be considered as putative hits for Pim-1 kinase inhibition.

8-Hydroxyquinoline: a privileged structure with a broad-ranging pharmacological potential

An overview of the broad-ranging pharmacological applications of 8-HQ derivatives.

Synthesis, characterization and spectroscopic behavior of novel 2-oxo-1,4-disubstituted-1,2,5,6-tetrahydrobenzo[h]quinoline-3-carbonitrile dyes

Two synthetic pathways were adopted to synthesize the target 2-oxo-1,4-disubstituted-1,2,5,6-tetrahydro-benzo[h]quinoline-3-carbonitriles. Structure of the synthesized compounds has been characterized based on FT-IR, (1)H NMR, (13)C NMR and elemental analyses. UV-Vis and fluorescence spectroscopy measurements provided that all compounds are good absorbent and fluorescent. Fluorescence polarity study demonstrated that these compounds were sensitive to the polarity of the microenvironment provided by different solvents. In addition, spectroscopic and physicochemical parameters, including singlet absorption, extinction coefficient, Stokes shift, oscillator strength and dipole moment were investigated in order to explore the analytical potential of synthesized compounds.

Small molecule inhibitors of PIM1 kinase: July 2009 to February 2013 patent update

INTRODUCTION

The proviral insertion in murine (PIM) lymphoma proteins for which three isoforms, PIM1, PIM2 and PIM3 have been identified, belonging to the family of serine/threonine kinases has emerged recently as an important therapeutic target for the development of selective inhibitors as the new drugs for treating hematological malignancies and solid tumors. The small molecules developed by academia and the pharmaceutical industry have steadily increased in the last few years. Several drug discovery groups focus on treating disorders, such as cancer mediated by PIM kinase, have provided preclinical evidence suggesting that PIM inhibitor provides anti-apoptotic activity, inhibit cell survival and cell proliferation.

AREAS COVERED

This article discloses recent reviews on research and advances published in the patent literature and scientific publications from July 2009 to February 2013, highlighting discoveries on PIM1 kinase.

EXPERT OPINION

Several PIM1 kinase small molecule inhibitors are now at the pre-clinical research stage, development and testing. Though nearly 40 patents emerged in the last 3 years, greater efforts towards additional designs and medicinal chemistry continues for developing clinically efficacious PIM1 inhibitors, due to the significance of the target for cancer and the potential for novel and diverse inhibitors as drug candidates.

Photo-physics study of an hydroxy-quinoline derivative as inhibitor of Pim-1 kinase: ultraviolet-visible linear dichroism spectroscopy and quantum chemical calculations

The photophysical properties of the antiviral 7-nicotinoyl-styrylquinoline (MB96) were investigated by means of UV-Vis linear dichroism (LD) spectroscopy on molecular samples aligned in stretched polyvinylalcohol (PVA), supported by time dependent density functional theory (TD-DFT) calculations. Experimentally, the directions of the transitions moments with respect to the long axis of the molecule were deduced from the orientation K factors, determined by means of "trial-and-error" procedure. The absorption spectrum presents two parts. The main transition in the lowest energy part, observed around 365 nm and showing the highest K value 0.8, is longitudinally in-plane polarized. The highest energy part which is extended between 230 and 320 nm, large, diffuse, and of weak intensity, shows estimated K values between 0.2 and 0.5. This complex structure is transversally polarized with some contamination by the longitudinal character of the first strong band. The TD-DFT results agree fairly well with the LD measurements.

A combination strategy to inhibit Pim-1: synergism between noncompetitive and ATP-competitive inhibitors

Pim-1 is a serine/threonine kinase critically involved in the initiation and progression of various types of cancer, especially leukemia, lymphomas and solid tumors such as prostate, pancreas and colon, and is considered a potential drug target against these malignancies. In an effort to discover new potent Pim-1 inhibitors, a previously identified ATP-competitive indolyl-pyrrolone scaffold was expanded to derive structure-activity relationship data. A virtual screening campaign was also performed, which led to the discovery of additional ATP-competitive inhibitors as well as a series of 2-aminothiazole derivatives, which are noncompetitive with respect to both ATP and peptide substrate. This mechanism of action, which resembles allosteric inhibition, has not previously been characterized for Pim-1. Notably, further evaluation of the 2-aminothiazoles indicated a synergistic inhibitory effect in enzymatic assays when tested in combination with ATP-competitive inhibitors. A synergistic effect in the inhibition of cell proliferation by ATP-competitive and ATP-noncompetitive compounds was also observed in prostate cancer cell lines (PC3), where all Pim-1 inhibitors tested in showed synergism with the known anticancer agent, paclitaxel. These results further establish Pim-1 as a target in cancer therapy, and highlight the potential of these agents for use as adjuvant agents in the treatment of cancer diseases in which Pim-1 is associated with chemotherapeutic resistance.

PIM1 kinase as a target for cancer therapy

INTRODUCTION

Inhibition of protein kinases has become a standard of modern clinical oncology. PIM1 belongs to a novel class of serine/threonine kinases with distinct molecular and biochemical features regulating various oncogenic pathways, for example hypoxia response, cell cycle progression and apoptosis resistance. PIM1 is overexpressed in human cancer diseases and has been associated with metastasis and overall treatment response; in experimental models, inhibition of PIM1 suppressed cell proliferation and migration, induced apoptotic cell death and synergized with other chemotherapeutic agents.

AREAS COVERED

A PubMed literature search was performed to review the currently available data on PIM1 expression, regulation and targets; its implication in different types of cancer and its impact on prognosis are described. We present ATP-competitive PIM1 inhibitors and the state of the art of PIM1 inhibitor design. Finally, we highlight the development of the unusual class of highly selective and potent organometallic PIM1 inhibitors.

EXPERT OPINION

As PIM1 possesses oncogenic functions and is overexpressed in various kinds of cancer diseases, its inhibition provides a new option in cancer therapy. Based on the ability of highly selective organometallic PIM1 inhibitors, promising in vivo applicability is expected.

High-throughput kinase profiling: a more efficient approach toward the discovery of new kinase inhibitors

Selective protein kinase inhibitors have only been developed against a small number of kinase targets. Here we demonstrate that "high-throughput kinase profiling" is an efficient method for the discovery of lead compounds for established as well as unexplored kinase targets. We screened a library of 118 compounds constituting two distinct scaffolds (furan-thiazolidinediones and pyrimido-diazepines) against a panel of 353 kinases. A distinct kinase selectivity profile was observed for each scaffold. Selective inhibitors were identified with submicromolar cellular activity against PIM1, ERK5, ACK1, MPS1, PLK1-3, and Aurora A,B kinases. In addition, we identified potent inhibitors for so far unexplored kinases such as DRAK1, HIPK2, and DCAMKL1 that await further evaluation. This inhibitor-centric approach permits comprehensive assessment of a scaffold of interest and represents an efficient and general strategy for identifying new selective kinase inhibitors.

Discovery of novel Pim-1 kinase inhibitors by a hierarchical multistage virtual screening approach based on SVM model, pharmacophore, and molecular docking

In this investigation, we describe the discovery of novel potent Pim-1 inhibitors by employing a proposed hierarchical multistage virtual screening (VS) approach, which is based on support vector machine-based (SVM-based VS or SB-VS), pharmacophore-based VS (PB-VS), and docking-based VS (DB-VS) methods. In this approach, the three VS methods are applied in an increasing order of complexity so that the first filter (SB-VS) is fast and simple, while successive ones (PB-VS and DB-VS) are more time-consuming but are applied only to a small subset of the entire database. Evaluation of this approach indicates that it can be used to screen a large chemical library rapidly with a high hit rate and a high enrichment factor. This approach was then applied to screen several large chemical libraries, including PubChem, Specs, and Enamine as well as an in-house database. From the final hits, 47 compounds were selected for further in vitro Pim-1 inhibitory assay, and 15 compounds show nanomolar level or low micromolar inhibition potency against Pim-1. In particular, four of them were found to have new scaffolds which have potential for the chemical development of Pim-1 inhibitors.