Imidazo[1,2- a ]pyridines linked with thiazoles/thiophene motif through keto spacer as potential cytotoxic agents and NF-κB inhibitors

Development of novel tetrazole-based pyruvate kinase M2 inhibitors targeting U87MG glioblastoma cells

Glioblastoma (GB), the most aggressive and life-threatening primary brain tumor in adults, poses significant therapeutic challenges. Tumor pyruvate kinase M2 (PKM2) has been implicated in the proliferation and survival of glioma cells. In this study, we designed and synthesized a series of 23 novel tetrazole-based derivatives. The compounds were thoroughly characterized using 1H, 13C, 19F NMR, along with HRMS analysis. Among them, 1-(imidazo[1,2-a]pyrimidin-3-yl)-2-(5-(naphthalen-2-yl)-2H-tetrazol-2-yl)ethan-1-one (9b) exhibited potent and selective antiproliferative activity against U87MG glioma cells, with minimal effects on bEnd (brain endothelial cell line) non-glioma cells. It emerged as a potent PKM2 inhibitor, with an IC50 of 0.307 µM. Apoptosis assays and cell cycle analysis revealed that compound 9b induced early apoptosis and caused G1 phase arrest. A significant decrease in pyruvate concentration further suggested PKM2 inhibition. In silico studies confirmed the binding affinity to the PKM2 inhibitory site, and RT-PCR data demonstrated its inhibitory activity against PKM2. Additionally, it reduced lactate levels, indicating its potential impact on cellular metabolism. Collectively, these findings suggest that the most potent compound holds promise as a therapeutic candidate against GB.

Novel sulfonamides unveiled as potent anti-lung cancer agents via tumor pyruvate kinase M2 activation

This rational pursuit led to the identification of a novel sulfonamide derivative as a potent anti-lung cancer (LC) compound. Considering these results, we synthesized 38 novel sulfonamide derivatives with diverse skeletal structures. In vitro cytotoxicity assays revealed a potent and selective antiproliferative effect against A549 cells after evaluating a panel of cancer cell lines. Compound 9b has emerged as a potent activator of tumor pyruvate kinase M2 (PKM2), a protein known to play a critical role in LC. Apoptosis assays and cell cycle analysis demonstrated early apoptosis and G2 phase arrest. In silico studies demonstrated interactions between compound 9b and the activator binding site of PKM2. Surface plasmon resonance (SPR) experiments strongly indicated that 9b has a high affinity (K d of 1.378 nM) for PKM2. Furthermore, the increase in reactive oxygen species and decrease in lactate concentration suggested that compound 9b has significant anticancer effects. Notably, the increase in particle size following treatment with 9b suggested the tetramerization of PKM2. This work provides insights that might advance efforts to develop effective non-platinum anticancer agents.

Targeted suppression of oral squamous cell carcinoma by pyrimidine-tethered quinoxaline derivatives

Oral cancer (OC) stands as a prominent cause of global mortality. Despite numerous efforts in recent decades, the efficacy of novel therapies to extend the lifespan of OC patients remains disappointingly low. Consequently, the demand for innovative therapeutic agents has become all the more pressing. In this context, we present our work on the design and synthesis of twenty-five novel quinoxaline-tethered imidazopyri(mi)dine derivatives. This was followed by comprehensive investigations into the impact of these molecules on the OC cell line. The in vitro cytotoxicity studies performed in CAL-27 and normal oral epithelial (NOE) cell lines revealed that some of the synthesized molecules like 12d have potent antiproliferative activity specifically towards OC cells with an IC50 of 0.79 μM and show negligible cytotoxicity over NOE cells. Further, 12d arrested cell growth in the S phase of the cell cycle and induced cell death by early apoptosis. The in silico studies validated that 12d binds to the activator binding site on pyruvate kinase M2 (PKM2) overexpressed in OC while the lactate dehydrogenase (LDH)-coupled enzyme assay established 12d as a potent PKM2 activator with an AC50 of 0.6 nM. Hence, this study provides fruitful evidence for the designed compounds as anticancer agents against OC.

Imidazopyrimidine: from a relatively exotic scaffold to an evolving structural motif in drug discovery

Nitrogen-fused heterocycles are of immense importance in modern drug discovery and development. Among them, imidazopyrimidine is a highly versatile scaffold with vast pharmacological utility. These compounds demonstrate a broad spectrum of pharmacological actions, including antiviral, antifungal, anti-inflammatory, and anticancer. Their adaptable structure allows for extensive structural modifications, which can be utilized for optimizing pharmacological effects via structure-activity relationship (SAR) studies. Additionally, imidazopyrimidine derivatives are particularly noteworthy for their ability to target specific molecular entities, such as protein kinases, which are crucial components of various cellular signaling pathways associated with multiple diseases. Despite the evident importance of imidazopyrimidines in drug discovery, there is a notable lack of a comprehensive review that outlines their role in this field. This review highlights the ongoing interest and investment in exploring the therapeutic potential of imidazopyrimidine compounds, underscoring their pivotal role in shaping the future of drug discovery and clinical medicine.

Development in the Synthesis of Bioactive Thiazole-Based Heterocyclic Hybrids Utilizing Phenacyl Bromide

Heterocyclic hybrid frameworks represent a burgeoning domain within the realms of drug discovery and medicinal chemistry, attracting considerable attention in recent years. Thiazole pharmacophore fragments, inherent in natural products such as peptide alkaloids, metabolites, and cyclopeptides, have demonstrated a broad spectrum of pharmacological potentials. Given their profound biological significance, a plethora of thiazole-based hybrids have been synthesized through the conjugation of thiazole moieties with bioactive pyrazole and pyrazoline fragments. This review systematically presents a compendium of robust methodologies for the synthesis of thiazole-linked hybrids, employing the (3 + 2) heterocyclization reaction, specifically the Hantzsch-thiazole synthesis, utilizing phenacyl bromide as the substrate. The strategic approach of molecular hybridization has markedly enhanced drug efficacy, mitigated resistance to multiple drugs, and minimized toxicity concerns. The resultant thiazole-linked hybrids exhibit a myriad of medicinal properties viz. anticancer, antibacterial, anticonvulsant, antifungal, antiviral, and antioxidant activities. This compilation of methodologies and insights serves as a valuable resource for medicinal chemists and researchers engaged in the design of novel thiazole-linked hybrids endowed with therapeutic attribute.

Mechanistic Investigation of Thiazole-Based Pyruvate Kinase M2 Inhibitor Causing Tumor Regression in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a deadly breast cancer with a poor prognosis. Pyruvate kinase M2 (PKM2), a key rate-limiting enzyme in glycolysis, is abnormally highly expressed in TNBC. Overexpressed PKM2 amplifies glucose uptake, enhances lactate production, and suppresses autophagy, thereby expediting the progression of oncogenic processes. A high mortality rate demands novel chemotherapeutic regimens at once. Herein, we report the rational development of an imidazopyridine-based thiazole derivative 7d as an anticancer agent inhibiting PKM2. Nanomolar range PKM2 inhibitors with favorable drug-like properties emerged through enzyme assays. Experiments on two-dimensional (2D)/three-dimensional (3D) cell cultures, lactate release assay, surface plasmon resonance (SPR), and quantitative real-time polymerase chain reaction (qRT-PCR) validated 7d preclinically. In vivo, 7d outperformed lapatinib in tumor regression. This investigation introduces a lead-based approach characterized by its clear-cut chemistry and robust efficacy in designing an exceptionally potent inhibitor targeting PKM2, with a focus on combating TNBC.

A novel imidazo[1,2-a]pyridine derivative and its co-administration with curcumin exert anti-inflammatory effects by modulating the STAT3/NF-κB/iNOS/COX-2 signaling pathway in breast and ovarian cancer cell lines

Introduction

Imidazo[1,2-a]pyridine derivatives with diverse pharmacological properties and curcumin, as a potential natural anti-inflammatory compound, are promising compounds for cancer treatment. This study aimed to synthesize a novel imidazo[1,2-a]pyridine derivative, (MIA), and evaluate its anti-inflammatory activity and effects on nuclear factor-κB (NF-κB) and signal transducer and activator of transcription 3 (STAT3) pathways, and their target genes, alone and in combination with curcumin, in MDA-MB-231 and SKOV3 cell lines.

Methods

We evaluated the interaction between imidazo[1,2-a]pyridine ligand, curcumin, and NF-κB p50 protein, using molecular docking studies. MTT assay was used to investigate the impacts of compounds on cell viability. To evaluate the NF-κB DNA binding activity and the level of inflammatory cytokines in response to the compounds, ELISA-based methods were performed. In addition, quantitative polymerase chain reaction (qPCR) and western blotting were carried out to analyze the expression of genes and investigate NF-κB and STAT3 signaling pathways.

Results

Molecular docking studies showed that MIA docked into the NF-κB p50 subunit, and curcumin augmented its binding. The MTT assay results indicated that MIA and its combination with curcumin reduced cell viability. According to the results of the ELISA-based methods, MIA lowered the levels of inflammatory cytokines and suppressed NF-κB activity. In addition, real-time PCR and Griess test results showed that the expression of cyclooxygenase-2 (COX-2) and inducible NO synthase (iNOS) genes, and nitrite production were reduced by MIA. Furthermore, the western blotting analysis demonstrated that MIA increased the expression of inhibitory κB (IκBα) and B-cell lymphoma 2 (Bcl-2)-associated X proteins (BAX), and suppressed the STAT3 phosphorylation, and Bcl-2 expression. Our findings revealed that curcumin had a potentiating role and enhanced all the anti-inflammatory effects of MIA.

Conclusion

This study indicated that the anti-inflammatory activity of MIA is exerted by suppressing the NF-κB and STAT3 signaling pathways in MDA-MB-231 and SKOV3 cancer cell lines.

Synthesis, In Vitro Evaluation and Molecular Docking Studies of Novel Thiophenyl Thiazolyl-Pyridine Hybrids as Potential Anticancer Agents

Many literature reports revealed the anticancer activity of pyridine and thiazole derivatives, especially in lung cancer. Therefore, a new series of thiazolyl pyridines linked with thiophene moiety via hydrazone group was prepared by one-pot multi-component reaction of (E)-1-(4-methyl-2-(2-(1-(thiophen-2-yl)ethylidene)hydrazinyl)thiazol-5-yl)ethanone with benzaldehyde derivatives and malononitrile in a good yield. Then, compound 5 and the thiazolyl pyridines were investigated for their in vitro anticancer activity against lung cancer (A549) cell line using MTT assay compared to doxorubicin as a reference drug. The structure of all the newly synthesized compounds was established based on spectroscopic data and elemental analyses. For better insight to investigate their mechanism of action on A549 cell line, docking studies were performed, targeting epidermal growth factor receptor (EGFR) tyrosine kinase. The results obtained revealed that the tested compounds displayed excellent anticancer activities against lung cancer cell line except 8c and 8f compared to reference drug. Based on the data obtained, it can be inferred that the novel compounds, as well as their key intermediate, compound 5, demonstrated potent anticancer activity against lung carcinoma by inhibiting EGFR.

Novel imidazopyrimidines-based molecules induce tetramerization of tumor pyruvate kinase M2 and exhibit potent antiproliferative profile

Discovery of novel and potent lead molecules for the specific therapeutic targets by de novo drug design is still in infancy. Here, we disclose the unprecedented development of imidazopyri(mi)dine-based tumor pyruvate kinase M2 (PKM2) modulators by subsequent link and grow strategy. The most potent modulator 15n acts as a PKM2 activator with an AC₅₀ of 90 nM, with considerable cancer cell-selectivity and membrane-permeability. NMR metabolomics studies also revealed that treatment with 15n results in diminution in lactate concentrations in MCF-7 cells. 15n binds to a previously reported site at PKM2 adjacent to the interface of two monomers. In molecular dynamics (MD) simulation studies, it was observed that 15n stabilizes the PKM2 at the dimeric interface, assisting in the formation of a biologically active tetramer conformation. 15n was also screened on MCF-7 breast cancer cell lines grown on 3-D scaffolds, and the results exhibited better anticancer potential compared to control, paving the way for future clinical studies.

Gas-phase fragmentation of protonated 3-phenoxy imidazo[1,2-a] pyridines using tandem mass spectrometry and computational chemistry

Imidazo[1,2-a] pyridine is one of the pharmaceutically important scaffolds and has been widely studied due to its extensive biological activities. In this work, electrospray ionization tandem mass spectrometry (ESI-MS/MS) in positive mode was used to study the gas-phase fragmentation behavior of a series of 3-phenoxy imidazo[1,2-a] pyridines. Proposed fragmentation pathways were supported by ESI-MS/MS data and computational thermochemistry. Homolytic cleavage of the 3-phenoxy C-O bond was the characteristic fragmentation of 3-phenoxy imidazo [1,2-a] pyridines. The eliminations of the one substituted phenoxy radical and CO produced other diagnostic ions for 3-phenoxy imidazo [1,2-a] pyridines, which were useful to identify the 3-phenoxy group and imidazo [1,2-a] pyridine scaffold. The results contribute to the further understanding of the gas-phase fragmentation of 3-phenoxy imidazo [1,2-a] pyridines and the identification of other analogs using tandem mass spectrometry techniques.

Investigations on substituted (2-aminothiazol-5-yl)(imidazo[1,2-a]pyridin-3-yl)methanones for the treatment of Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disease majorly affecting old age populations. Various factors that affect the progression of the disease include, amyloid plaque formation, neurofibrillary tangles, inflammation, oxidative stress, etc. Herein we report of a new series of substituted (2-aminothiazol-5-yl)(imidazo[1,2-a]pyridin-3-yl)methanones. The designed compounds were synthesized and characterized by spectral data. In vivo anti-inflammatory activity was carried out for screening of anti-inflammatory potential of synthesized compounds. All the compounds were tested for acute inflammatory activity by using carrageenan induced acute inflammation model. Compounds 10b, 10c, and 10o had shown promising acute anti-inflammatory activity and they were further tested for formalin induced chronic inflammation model. Compound 10c showed both acute and chronic anti-inflammatory activity. Compound 10c also showed promising results in AlCl₃ induced AD model. Studies on various behavioral parameters suggested improved amnesic performance of compound 10c treated rats. Compound 10c treated rats also exhibited excellent antioxidant and neuroprotective effect with inherent gastrointestinal safety.

Medicinal attributes of pyridine scaffold as anticancer targeting agents

Background

The heterocyclic compounds particularly pyridine displayed clinical and biological implementation. Pyridine scaffolds have been detected in most relevant drug molecules that included pyridine provided a great possibility for treatment.

Main text

Pyridine-containing compounds have increasing importance for medicinal application as antiviral, anticholinesterase activities, antimalarial, antimicrobial, antidiabetic and anticancer. This has generated concern among researchers in synthesising a variety of pyridine derivatives.

Conclusion

This review focuses on different pyridine targets as anticancer and their pharmacophoric elements controlling its activity.

Recent advances of thiazole hybrids in biological applications

Thiazoles have attracted much synthetic interest due to their wide variety of biological properties and are important members of heterocyclic compounds. In recent years, studies on the synthesis of thiazole compounds have been increasing because of the properties of this core. In particular, the hybrid structures in which the thiazole ring and the other nuclei are linked have gained popularity. Hybrid structures are formed by the combination of different groups of chemical reactivity and biological activity characteristics. In this review, we highlight recent developments related to hybrid structures containing a thiazole core, recently developed as anticancer, antibacterial, anti-inflammatory, analgesic, anti-tubercular, antialzheimer and antidiabetic compounds.

Mn-mediated sequential three-component domino Knoevenagel/cyclization/Michael addition/oxidative cyclization reaction towards annulated imidazo[1,2-a]pyridines

The sequential three-component reaction between o-hydroxybenzaldehydes, N-(cyanomethyl)pyridinium salts and a nucleophile towards substituted chromenoimidazopyridines under oxidative conditions has been developed. The employment of Mn(OAc)₃·2H₂O or KMnO₄ as stoichiometric oxidants allowed the use of a wide range of nucleophiles, such as nitromethane, (aza)indoles, pyrroles, phenols, pyrazole, indazole and diethyl malonate. The formation of the target compounds presumably proceeds through a domino Knoevenagel/cyclization/Michael addition/oxidative cyclization reaction sequence.