Recent Applications of the Multicomponent Synthesis for Bioactive Pyrazole Derivatives

Gellan gum-cellulose hydrogel incorporating with graphene oxide and magnetic nanoparticles as a novel nanocatalyst for the synthesis of dihydropyrano derivatives

In this project, a highly efficient catalyst with a remarkable yield of over 97 % was developed for the synthesis of dihydropyrano[2,3-c] pyrazole derivatives. A Gellan Gum-Cellulose hydrogel was prepared using Glutaraldehyde as the cross-linker, which served as the matrix for further modifications. Synthesized graphene oxide was then incorporated into the hydrogel structure using a modified Hummers method, enhancing the catalytic properties of the material. To facilitate the separation and recovery of the catalyst, the resulting structure was magnetized, leading to the formation of a magnetic nanocomposite. Even after undergoing four cycles of catalyst recovery, the GG-Cell hydrogel/GO/Fe3O4 nanocomposite retained 90 % of its initial catalytic activity, highlighting its robustness and stability. Detailed physical and chemical analyses were conducted to gain a comprehensive understanding of the synthesized magnetic catalyst, contributing to the advancement of the field of catalysis and holding great potential for various applications in organic synthesis and related fields.

Cs2CO3-Promoted Alkylation of 3-Cyano-2(1H)-Pyridones: Anticancer Evaluation and Molecular Docking

Herein, a Cs2CO3-promoted N-alkylation of 3-cyano-2(1H)-pyridones containing alkyl groups with diverse alkyl halides to synthesize N-alkyl-2-pyridones over O-alkylpyridines is reported. The use of alkyl dihalides resulted in complex mixtures of N- and O-alkylated products. The primary factor influencing regioselectivity in these reactions is the electronic effects of substituents on the 2(1H)-pyridone ring, as evidenced by the preferential formation of O-alkylpyridines upon the introduction of aryl groups. Remarkably, we efficiently employed CuAAC and Ti(Oi-Pr)4-catalyzed amidation reactions to functionalize N-alkyl-2-pyridones containing propargyl and ester groups, leading to the synthesis of 1,2,3-triazoles and amides, respectively. Moreover, O-alkylpyridines 10 b and 10 d displayed remarkable selectivity toward the A-498 renal cancer cell line with growth inhibition percentages (%GI) of 54.75 and 67.64, respectively. The binding modes of compounds 10 b and 10 d to the PIM-1 kinase enzyme were determined through molecular docking studies.

Multicomponent syntheses of pyrazoles via (3 + 2)-cyclocondensation and (3 + 2)-cycloaddition key steps

Pyrazoles are rarely found in nature but are traditionally used in the agrochemical and pharmaceutical industries, while other areas of use are also actively developing. However, they have also found numerous other applications. The search for new and efficient syntheses of these heterocycles is therefore highly relevant. The modular concept of multicomponent reactions (MCR) has paved a broad alley to heteroaromatics. The advantages over traditional methods are the broader scope and increased efficiency of these reactions. In particular, traditional multistep syntheses of pyrazoles have considerably been extended by MCR. Progress has been made in the cyclocondensation of 1,3-dielectrophiles that are generated in situ. Limitations in the regioselectivity of cyclocondensation with 1,3-dicarbonyls were overcome by the addition-cyclocondensation of α,β-unsaturated ketones. Embedding 1,3-dipolar cycloadditions into a one-pot process has additionally been developed for concise syntheses of pyrazoles. The MCR strategy also allows for concatenating classical condensation-based methodology with modern cross-coupling and radical chemistry, as well as providing versatile synthetic approaches to pyrazoles. This overview summarizes the most important MCR syntheses of pyrazoles based on ring-forming sequences in a flashlight fashion.

Crystal structure, spectroscopy, DFT, and thermal studies of 3-cyano-2(1H)-pyridones as potential anticancer agents

A series of 3-cyano-2(1H)-pyridones 4a-c were efficiently synthesized using an expeditious microwave-assisted multicomponent approach. Single-crystal XRD analysis revealed the presence of six independent molecules in the asymmetric unit cell for all compounds, with the crystal packing stabilized by a network of cyclic dimers formed by N-H⋯O[double bond, length as m-dash]C and C-H⋯O[double bond, length as m-dash]C intermolecular interactions. Additional supramolecular interactions, including C-H⋯π, C-N⋯π, and π⋯π, and C-H⋯X (for halogenated derivatives, i.e., 4b and 4c), appear crucial for crystal stabilization. Density Functional Theory (DFT) calculations were employed to understand the electronic structures and potential binding affinities. Comprehensive spectroscopic characterization by FT-IR, UV-Vis, NMR, and HMRS techniques confirmed the structures of all synthesized compounds. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were employed to evaluate the thermal stability of these compounds. The in vitro anticancer activity was evaluated against a panel of 60 human cancer cell lines, demonstrating promising activity against non-small-cell lung and breast cancer cell lines. Notably, compounds 4a and 4c exhibited the highest anticancer activity against the HOP-92 and MCF7 cell lines, with growth inhibition percentages (GI%) of 54.35 and 40.25, respectively.

Synthesis, DFT, and in silico biological evaluation of chalcone bearing pyrazoline ring against Helicobacter pylori receptors

Peptic ulcer disease (PUD), often caused by Helicobacter pylori infection, is a prevalent gastrointestinal condition characterized by the erosion of the gastric or duodenal mucosal lining. H. pylori adheres to gastric epithelial cells, secreting toxins and disrupting the stomach's defenses. H. pylori relies on various receptors to establish infection, making these molecules attractive therapeutic targets. This study aimed to develop novel anti-ulcer compounds by combining benzothiazole, pyrazoline, and chalcone pharmacophores. A series of chalcone derivatives 4a-c were synthesized via Claisen-Schmidt condensation and characterized using spectroscopic techniques such as FT-IR, NMR and elemental analysis. The DFT calculations, using B3LYP method with 6-311G basis set, revealed the p-tolyl derivative 4b exhibited the highest thermal stability while the p-bromophenyl derivative 4c showed the lowest stability but highest chemical reactivity. The HOMO-LUMO energy gaps as well as the dipole moments decreased in the order: 4b > 4a > 4c, reflecting a similar reactivity trend. Molecular docking showed ligands 4a-c bound effectively to the H. pylori urease enzyme, with docking scores from -5.3862 to -5.7367 kcal/mol with superior affinity over lansoprazole. Key interactions involved hydrogen bonds and hydrophobic pi-hydrogen bonds with distances ranging 3.46-4.34 Å with active site residues ASN666, SER714 and ASN810. The combined anti-inflammatory, antimicrobial, and H. pylori anti-adhesion properties make these novel chalcones promising PUD therapeutic candidates.

Multicomponent Synthesis of New Fluorescent Boron Complexes Derived from 3-Hydroxy-1-phenyl-1H-pyrazole-4-carbaldehyde

Novel fluorescent pyrazole-containing boron (III) complexes were synthesized employing a one-pot three-component reaction of 3-hydroxy-1-phenyl-1H-pyrazole-4-carbaldehyde, 2-aminobenzenecarboxylic acids, and boronic acids. The structures of the novel heterocyclic compounds were confirmed using 1H-, 13C-, 15N-, 19F-, and 11B-NMR, IR spectroscopy, HRMS, and single-crystal X-ray diffraction data. The photophysical properties of the obtained iminoboronates were investigated using spectroscopic techniques, such as UV-vis and fluorescence spectroscopies. Compounds display main UV-vis absorption maxima in the blue region, and fluorescence emission maxima are observed in the green region of the visible spectrum. It was revealed that compounds exhibit fluorescence quantum yield up to 4.3% in different solvents and demonstrate an aggregation-induced emission enhancement effect in mixed THF-water solutions.

Recent Advances in Design and Development of Diazole and Diazine Based Fungicides (2014-2023)

With fungal diseases posing a major threat to agricultural production, the application of fungicides to control related diseases is often considered necessary to ensure the world's food supply. The search for new bioactive agents has long been a priority in crop protection due to the continuous development of resistance against currently used types of active compounds. Heterocyclic compounds are an inseparable part of the core structures of numerous lead compounds, these rings constitute pharmacophores of a significant number of fungicides developed over the past decade by agrochemists. Among heterocycles, nitrogen-based compounds play an essential role. To date, diazole (imidazole and pyrazole) and diazine (pyrimidine, pyridazine, and pyrazine) derivatives make up an important series of synthetic fungicides. In recent years, many reports have been published on the design, synthesis, and study of the fungicidal activity of these scaffolds, but there was a lack of a comprehensive classified review on nitrogen-containing scaffolds. Regarding this issue, here we have reviewed the published articles on the fungicidal activity of the diazole and diazine families. In current review, we have classified the molecules synthesized so far based on the size of the ring.

N-Heterocycles as Promising Antiviral Agents: A Comprehensive Overview

Viruses are a real threat to every organism at any stage of life leading to extensive infections and casualties. N-heterocycles can affect the viral life cycle at many points, including viral entrance into host cells, viral genome replication, and the production of novel viral species. Certain N-heterocycles can also stimulate the host's immune system, producing antiviral cytokines and chemokines that can stop the reproduction of viruses. This review focused on recent five- or six-membered synthetic N-heterocyclic molecules showing antiviral activity through SAR analyses. The review will assist in identifying robust scaffolds that might be utilized to create effective antiviral drugs with either no or few side effects.

Synthesis, In Silico Study, and In Vitro Antifungal Activity of New 5-(1,3-Diphenyl-1H-Pyrazol-4-yl)-4-Tosyl-4,5-Dihydrooxazoles

The increase in multi-drug resistant Candida strains has caused a sharp rise in life-threatening fungal infections in immunosuppressed patients, including those with SARS-CoV-2. Novel antifungal drugs are needed to combat multi-drug-resistant yeasts. This study aimed to synthesize a new series of 2-oxazolines and evaluate the ligands in vitro for the inhibition of six Candida species and in silico for affinity to the CYP51 enzymes (obtained with molecular modeling and protein homology) of the same species. The 5-(1,3-diphenyl-1H-pyrazol-4-yl)-4-tosyl-4,5-dihydrooxazoles 6a-j were synthesized using the Van Leusen reaction between 1,3-diphenyl-4-formylpyrazoles 4a-j and TosMIC 5 in the presence of K2CO3 or KOH without heating, resulting in short reaction times, high compound purity, and high yields. The docking studies revealed good affinity for the active site of the CYP51 enzymes of the Candida species in the following order: 6a-j > 4a-j > fluconazole (the reference drug). The in vitro testing of the compounds against the Candida species showed lower MIC values for 6a-j than 4a-j, and for 4a-j than fluconazole, thus correlating well with the in silico findings. According to growth rescue assays, 6a-j and 4a-j (like fluconazole) inhibit ergosterol synthesis. The in silico toxicity assessment evidenced the safety of compounds 6a-j, which merit further research as possible antifungal drugs.

Structure-Activity Relationship Studies on Highly Functionalized Pyrazole Hydrazones and Amides as Antiproliferative and Antioxidant Agents

Aminopyrazoles represent interesting structures in medicinal chemistry, and several derivatives showed biological activity in different therapeutic areas. Previously reported 5-aminopyrazolyl acylhydrazones and amides showed relevant antioxidant and anti-inflammatory activities. To further extend the structure-activity relationships in this class of derivatives, a novel series of pyrazolyl acylhydrazones and amides was designed and prepared through a divergent approach. The novel compounds shared the phenylamino pyrazole nucleus that was differently decorated at positions 1, 3, and 4. The antiproliferative, antiaggregating, and antioxidant properties of the obtained derivatives 10-22 were evaluated in in vitro assays. Derivative 11a showed relevant antitumor properties against selected tumor cell lines (namely, HeLa, MCF7, SKOV3, and SKMEL28) with micromolar IC50 values. In the platelet assay, selected pyrazoles showed higher antioxidant and ROS formation inhibition activity than the reference drugs acetylsalicylic acid and N-acetylcysteine. Furthermore, in vitro radical scavenging screening confirmed the good antioxidant properties of acylhydrazone molecules. Overall, the collected data allowed us to extend the structure-activity relationships of the previously reported compounds and confirmed the pharmaceutical attractiveness of this class of aminopyrazole derivatives.

Alamir H, Al-Shukarji AH, Ahmed BA, Qassem TA, Kamal M, Almeleebia TM, Alwaily ER, Hasan Kadhum E, Alawadi A, Alsalamy A. Choline chloride/urea as a green and efficient deep eutectic solvent in three-component and four-component synthesis of novel pyrazole and pyrano[2,3-c] pyrazole derivatives with antibacterial and antifungal activity

In this study, choline chloride/urea was used as a green deep eutectic solvent in the three-component reaction of hydrazine/phenylhydrazine, malononitrile, and aromatic aldehydes for synthesizing pyrazole derivatives, and in the four-component reaction of methyl/ethyl acetoacetate, hydrazine/phenylhydrazine, malononitrile, and aromatic aldehydes for synthesizing pyrano[2,3-c]pyrazole derivatives. Elemental analysis, 1H, and 13C NMR spectroscopy were used to confirm the structure of the synthesized pyrazole and pyrano[2,3-c] pyrazole derivatives. The antimicrobial effects of the synthesized pyrazole and pyrano[2,3-c] pyrazole derivatives were investigated. In antimicrobial tests, instructions from clinical and laboratory standards institutes were used. Antimicrobial study was done on pathogenic gram-positive and gram-negative species, and specialized aquatic strains and fungal species. Using choline chloride/urea, novel pyrazole derivatives and pyrano[2,3-c]pyrazole derivatives were synthesized, and other derivatives were synthesized with higher efficiency in less time than some previously reported methods. MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) obtained for derivatives were higher than some antibiotic drugs. Synthesis and reports of new derivatives of pyrazole and pyrano[2,3-c]pyrazole, and investigation and reports of their antimicrobial properties on gram-positive, gram-negative, and specialized aquatic and fungal species are among the novel and important findings of this study.

Nanomagnetic CoFe2O4@SiO2-EA-H3PO4 as a zwitterionic catalyst for the synthesis of bioactive pyrazolopyranopyrimidines and dihydropyrano[2,3-c]pyrazoles

This study presents the development of a phosphoric acid-based zwitterionic catalyst immobilized on CoFe2O4 nanoparticles [CoFe2O4@SiO2-EA-H3PO4]. The structure of the nanocatalyst CoFe2O4@SiO2-EA-H3PO4 was identified by applying several spectroscopic techniques, i.e. FT-IR, SEM, TEM, XRD, EDX, elemental Mapping, VSM, TGA, and BET techniques. The catalytic efficiency of CoFe2O4@SiO2-EA-H3PO4 was evaluated in the water-based multicomponent synthesis of pyrazolopyranopyrimidine and dihydropyrano[2,3-c]pyrazole derivatives. Subsequently, an exploration of the antibacterial properties of the compounds was conducted. The catalytic system offers several advantages, encompassing high efficiency, brief reaction duration, uncomplicated operation, and facile recycling of the catalyst.

Discovery of Pyrano[2,3-c]pyrazole Derivatives as Novel Potential Human Coronavirus Inhibitors: Design, Synthesis, In Silico, In Vitro, and ADME Studies

The SARS-CoV-2 pandemic at the end of 2019 had major worldwide health and economic consequences. Until effective vaccination approaches were created, the healthcare sectors endured a shortage of operative treatments that might prevent the infection's spread. As a result, academia and the pharmaceutical industry prioritized the development of SARS-CoV2 antiviral medication. Pyranopyrazoles have been shown to play a prominent function in pharmaceutical chemistry and drug sighting because of their significant bioactive properties. We provide herein a novel sequence of pyranopyrazoles and their annulated systems whose antiviral efficacy and cytotoxicity were explored versus human coronavirus 229E (HCoV-229E) Vero-E6 cell lines as a model for the Coronaviridae family. Fifteen synthetic congeners pointed out miscellaneous antiviral efficacies against HCoV-229E with variable inhibition degrees. Compound 18 showed a high selectivity index (SI = 12.6) that established spectacular inhibitory capacity against human coronavirus 229E. Compounds 6, 7, and 14 exposed moderate efficacies. Compounds 6, 7, 14, and 18 exhibited substantial antiviral action through the replication phase with reduction percentages extending from 53.6%, 60.7%, and 55% to 82.2%, correspondingly. Likewise, when assessed to the positive control tipranavir (88.6%), the inhibitory efficiency of compounds 6, 7, 14, and 18 versus the SARS-CoV2 Mpro provided high percentages of 80.4%, 73.1%, 81.4% and up to 84.5%, respectively. In silico studies were performed to investigate further the biological activity and the target compounds' physical and chemical features, including molecular dynamic (MD) simulations, protein-ligand docking, ADME studies, and density functional theory (DFT) calculations. These inquiries demonstrated that this series of metabolically stable pyranopyrazoles and their annulated systems are effective human coronavirus inhibitors that inhibit the viral Mpro protein and may have emerged as a novel COVID-19 curative option.

Synthesis, anticancer activity, molecular docking and molecular dynamics studies of some pyrazole-chalcone hybrids

Four new hybrid compounds (H1-H4) bearing pyrazole (S1 and S2) and chalcone (P1 and P2) fragments were synthesized and characterized. Compounds were assayed for their ability to inhibit the proliferation of human lung (A549) and colon (Caco-2) cancer cell lines. Besides, toxicity against normal cells was determined using the human umbilical vein endothelial cells (HUVEC). In silico molecular docking, molecular dynamics (MD) simulation and absorption, distribution, metabolism, excretion, and toxicity (ADMET) studies were carried out to predict the binding modes, protein stability, drug-likeness and toxicity of the reported compounds. The in vitro anticancer activity of the tested compounds revealed dose-dependent cell-specific cytotoxicity. In silico studies revealed that the compounds have a good binding affinity, possess appropriate drug-likeness properties and have low toxicity profiles.Communicated by Ramaswamy H. Sarma.

Pyrazoline Derivatives as Promising MAO-A Targeting Antidepressants: An Update

Depression is one of the key conditions addressed by the Mental Health Gap Action Programme (mhGAP) of WHO that can lead to self-harm and suicide. Depression is associated with low levels of neurotransmitters, which eventually play a key role in the progression and development of mental illness. The nitrogen-containing heterocyclic compounds exhibit the most prominent pharmacological profile as antidepressants. Pyrazoline, a dihydro derivative of pyrazole, is a well-known five-membered heterocyclic moiety that exhibits a broad spectrum of biological activities. Many researchers have reported pyrazoline scaffold-containing molecules as potential antidepressant agents with selectivity for monoamine oxidase enzyme (MAO) isoforms. Several studies indicated a better affinity of pyrazoline-based moiety as (monoamine oxidase inhibitors) MAOIs. In this review, we have focused on the recent advancements (2019-2023) in the development of pyrazoline-containing derivatives exhibiting promising inhibition of MAO-A enzyme to treat depression. This review provides structural insights on pyrazoline-based molecules along with their SAR analysis, in silico exploration of binding interactions between pyrazoline derivatives and MAO-A enzyme, and clinical trial status of various drug molecules against depression. The in-silico exploration of potent pyrazoline derivatives at the active site of the MAOA enzyme will provide further insights into the development of new potential MAO-A inhibitors for the treatment of depression.

Green Chemistry and In silico Techniques for Synthesis of Novel Pyranopyrazole and Pyrazolo-pyrano-pyrimidine Derivatives as Promising Antifungal Agents

BACKGROUND

Every year Invasive Fungal Infections (IFI) are globally affecting millions of people. Candida albicans and Aspergillus niger have been reported as the most infectious and mortality-inducing fungal strains among all pathogenic fungi.

AIMS & OBJECTIVES

To tackle this problem in the current study Pyranopyrazoles and Pyrazolopyrano- pyrimidine derivatives were developed using molecular hybridization, green chemistry and one-pot multicomponent reaction.

MATERIALS AND METHODS

In the present work, New Chemical entities (NCE's) were developed on the basis of Structure activity relationship. All designed NCE's were screened for ADMET studies using the QikProp module of Schrodinger software. NCE's with zero violations were further docked on the crystal structure of 14α demethylase, cytochrome P450 and thymidine synthase (PDB ID: 5V5Z, 7SHI, 1BID). Selected molecules were synthesized using green chemistry techniques and evaluated for in vitro antifungal activity against Candida albicans and Aspergillus niger.

RESULTS AND DISCUSSION

Designed NCE's (B1-12 and C1-11) showed favorable results in ADMET studies. In the docking study six compounds from series-B and five molecules from series- C showed good dock score and binding interaction when compared with the standard drugs. Compounds B-3 and C-4 showed the highest zone of inhibition activity against Candida albicans, where as B-1 and C-3 had shown highest zone of inhibition activity against Aspergillus niger.

CONCLUSION

Bicyclic ring (series B) showed better activity as compare to fused tricyclic ring (series C).

Identification of novel pyrazole containing ɑ-glucosidase inhibitors: insight into pharmacophore, 3D-QSAR, virtual screening, and molecular dynamics study

Pharmacophore modelling, 3 D QSAR modelling, virtual screening, and molecular dynamics study, all-in-one combination were employed successfully design and develop an alpha-glucosidase inhibitor. To explain the structural prerequisites of biologically active components, 3 D-QSAR models were generated using the selected best hypothesis (AARRR) for compounds 55 included in the model C. The selection of 3 D-QSAR models showed that the Gaussian steric characteristic is crucial to alpha glucosidase's inhibitory potential. The alpha-glucosidase inhibitory potency of the compound is enhanced by other components, including Gaussian hydrophobic groups, Gaussian hydrogen bond acceptor or donor groups, Gaussian electrostatic characteristics, and a Gaussian steric feature. An identification of structure-activity relationships can be obtained from the developed 3 D-QSAR, C model, with R2 = 0.77 and SD = 0.02 for training set, and Q2 = 0.66, RMSE 0.02, and Pearson R = 0.81 for testing set, corresponding to elevated predictive ability. Additionally, docking and MM/GBSA experiments on 1146023 showed that it interacts with critical amino acids in the binding site when coupled with acarbose. Further, five compounds that display a high affinity for alpha-glucosidase were found, and these compounds may serve as potent leads for alpha-glucosidase inhibitor development. Biological activity will be tested for these compounds in the future.Communicated by Ramaswamy H. Sarma.

Green multicomponent synthesis of pyrano[2,3-c]pyrazole derivatives: current insights and future directions

The past decade has witnessed significant progress in synthesizing structurally diverse and biologically relevant pyrano[2,3-c]pyrazole derivatives through the integration of green methodologies. This review summarizes the recent advances in the green multicomponent synthesis of pyrano[2,3-c]pyrazole and spiro-pyrano[2,3-c]pyrazole derivatives. These include the application of energy-efficient techniques such as microwave and ultrasound-assisted synthesis, benign catalysts and biodegradable composites, solvent selection with a focus on water as a renewable and non-toxic medium, and solvent-free conditions. The review consolidates the current knowledge and future research directions, providing a valuable resource for researchers dedicated to advancing green chemistry practices.

Synthesis and Biological Studies of Benzo[b]furan Derivatives: A Review from 2011 to 2022

The importance of the benzo[b]furan motif becomes evident in the remarkable results of numerous biological investigations, establishing its potential as a robust therapeutic option. This review presents an overview of the synthesis of and exhaustive biological studies conducted on benzo[b]furan derivatives from 2011 to 2022, accentuating their exceptional promise as anticancer, antibacterial, and antifungal agents. Initially, the discussion focuses on chemical synthesis, molecular docking simulations, and both in vitro and in vivo studies. Additionally, we provide an analysis of the intricate interplay between structure and activity, thereby facilitating comparisons and profoundly emphasizing the applications of the benzo[b]furan motif within the realms of drug discovery and medicinal chemistry.

Inherent efficacies of pyrazole-based derivatives for cancer therapy: the interface between experiment and in silico

There has been an increasing trend in the design of novel pyrazole derivatives for desired biological applications. For a cost-effective strategy, scientists have implemented various computational drug design tools to go hand in hand with experiments for the design and discovery of potentially effective pyrazole-based therapeutics. This review highlights the milestones of pyrazole-containing inhibitors and the use of molecular modeling techniques in conjunction with experimental studies to provide a view of the binding mechanism of these compounds. The review focuses on the established targets that play a key role in cancer therapy, including proteins involved in tubulin polymerization, carbonic anhydrase and tyrosine kinase. Overall, using both experimental and computational methods in drug design represents a promising approach to cancer therapy.

Special Issue "Recent Advances in the Synthesis, Functionalization and Applications of Pyrazole-Type Compounds II"

Pyrazole and its derivatives are considered privileged N-heterocycles with immense therapeutic potential [...].

New NADPH Oxidase 2 Inhibitors Display Potent Activity against Oxidative Stress by Targeting p22phox-p47phox Interactions

NADPH oxidase (NOX2) is responsible for reactive oxygen species (ROS) production in neutrophils and has been recognized as a key mediator in inflammatory and cardiovascular pathologies. Nevertheless, there is a lack of specific NOX2 pharmacological inhibitors. In medicinal chemistry, heterocyclic compounds are essential scaffolds for drug design, and among them, indole is a very versatile pharmacophore. We tested the hypothesis that indole heteroaryl-acrylonitrile derivatives may serve as NOX2 inhibitors by evaluating the capacity of 19 of these molecules to inhibit NOX2-derived ROS production in human neutrophils (HL-60 cells). Of these compounds, C6 and C14 exhibited concentration-dependent inhibition of NOX2 (IC₅₀~1 µM). These molecules also reduced NOX2-derived oxidative stress in cardiomyocytes and prevented cardiac damage induced by ischemia-reperfusion. Compound C6 significantly reduced the membrane translocation of p47^phox, a cytosolic subunit that is required for NOX2 activation. Molecular docking analyses of the binding modes of these molecules with p47^phox indicated that C6 and C14 interact with specific residues in the inner part of the groove of p47^phox, the binding cavity for p22^phox. This combination of methods showed that novel indole heteroaryl acrylonitriles represent interesting lead compounds for developing specific and potent NOX2 inhibitors.

Recent Advances in the Green Synthesis of Active N-Heterocycles and Their Biological Activities

N-heterocyclic scaffolds represent a privileged architecture in the process of drug design and development. It has widespread occurrence in synthetic and natural products, either those that are established or progressing as potent drug candidates. Additionally, numerous novel N-heterocyclic analogues with remarkable physiological significance and extended pharmaceutical applications are escalating progressively. Hence, the classical synthetic protocols need to be improvised according to modern requirements for efficient and eco-friendly approaches. Numerous methodologies and technologies emerged to address the green and sustainable production of various pharmaceutically and medicinally important N-heterocyclic compounds in last few years. In this context, the current review unveils greener alternatives for direct access to categorically differentiated N-heterocyclic derivatives and its application in the establishment of biologically active potent molecules for drug design. The green and sustainable methods accentuated in this review includes microwave-assisted reactions, solvent-free approaches, heterogeneous catalysis, ultrasound reactions, and biocatalysis.

Current scenario of pyrazole hybrids with in vivo therapeutic potential against cancers

Chemotherapeutics occupy a pivotal role in the medication of different types of cancers, but the prevalence and mortality rates of cancer remain high. The drug resistance and low specificity of current available chemotherapeutics are the main barriers for the effective cancer chemotherapy, evoking an immediate need for the development of novel anticancer agents. Pyrazole is a highly versatile five-membered heterocycle with two adjacent nitrogen atoms and possesses remarkable therapeutic effects and robust pharmacological potency. The pyrazole derivatives especially pyrazole hybrids have demonstrated potent in vitro and in vivo efficacies against cancers through multiple mechanisms, inclusive of apoptosis induction, autophagy regulation, and cell cycle disruption. Moreover, several pyrazole hybrids such as crizotanib (pyrazole-pyridine hybrid), erdafitinib (pyrazole-quinoxaline hybrid) and ruxolitinib (pyrazole-pyrrolo [2,3-d]pyrimidine hybrid) have already been approved for the cancer therapy, revealing that pyrazole hybrids are useful scaffolds to develop novel anticancer agents. The purpose of this review is to summarize the current scenario of pyrazole hybrids with potential in vivo anticancer efficacy along with mechanisms of action, toxicity, and pharmacokinetics, covering papers published in recent 5 years (2018-present), to facilitate further rational exploitation of more effective candidates.

Multicomponent Synthesis of Unsymmetrical Derivatives of 4-Methyl-Substituted 5-Nitropyridines

The multicomponent reaction of 2-nitroacetophenone (or nitroacetone), acetaldehyde diethyl acetal, β-dicarbonyl compound, and ammonium acetate in an acetic acid solution allowed the acquisition of previously undescribed 4-methyl-substituted derivatives of 5-nitro-1,4-dihydropyridine in satisfactory yields. The oxidation of the obtained 5-nitro-1,4-dihydropyridine derivatives resulted in the corresponding 2,4-dimethyl-5-nitropyridines. In addition, for the first time in the synthesis of unsymmetrical 1,4-dihydropyridines by the Hantzsch reaction acetaldehyde, diethyl acetal was used as a source of acetaldehyde. The use of more volatile and sufficiently reactive acetaldehyde in this reaction did not lead to a controlled synthesis of unsymmetrical 5-nitro-1,4-dihydropyridines. The proposed multicomponent approach to the synthesis of 4-methyl-substituted 5-nitro-1,4-dihydropyridines and their subsequent aromatization into pyridines made it possible to obtain previously undescribed and hardly accessible substituted 5(3)-nitropyridines.

Cu(ii) immobilized on poly(guanidine-sulfonamide)-functionalized Bentonite@MgFe2O4: a novel magnetic nanocatalyst for the synthesis of 1,4-dihydropyrano[2,3-c]pyrazole†

In this paper, we aim at synthesizing a new nanocomposite material in which bentonite acts as a nucleation site for MgFe₂O₄ nanoparticles precipitation in the attendance of an external magnetic field (MgFe₂O₄@Bentonite). Moreover, poly(guanidine-sulfonamide), as a novel kind of polysulfonamide, was immobilized on the surface of the prepared support (MgFe₂O₄@Bentonite@PGSA). Finally, an efficient and environment-friendly catalyst (containing nontoxic polysulfonamide, copper, and MgFe₂O₄@Bentonite) was prepared by anchoring a copper ion on the surface of MgFe₂O₄@Bentonite@PGSAMNPs. The synergic effect of MgFe₂O₄ magnetic nanoparticles (MNPs), bentonite, PGSA, and copper species was observed while conducting the control reactions. The synthesized Bentonite@MgFe₂O₄@PGSA/Cu, which was characterized using energy-dispersive X-ray spectroscopy (EDAX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Fourier-transform infrared (FT-IR) spectroscopy, was applied as a highly efficient heterogeneous catalyst to synthesize 1,4-dihydropyrano[2,3-c] pyrazole yielding up to 98% at 10 minutes. Excessive yield, quick reaction time, using water solvent, turning waste to wealth, and recyclability are the important advantages of the present work.

In this paper, we aim at synthesizing a new nanocomposite material in which bentonite acts as a nucleation site for MgFe₂O₄ nanoparticles precipitation in the attendance of an external magnetic field (MgFe₂O₄@Bentonite).

Bioactive 2-pyridone-containing heterocycle syntheses using multicomponent reactions

2-Pyridone-containing heterocycles are considered privileged scaffolds in drug discovery due to their behavior as hydrogen bond donors and/or acceptors and nonpeptidic mimics, and remarkable physicochemical properties such as metabolic stability, solubility in water, and lipophilicity. This review provides a comprehensive overview of multicomponent reactions (MCRs) for the synthesis of 2-pyridone-containing heterocycles. In particular, it covers the articles published from 1999 to date related to anticancer, antibacterial, antifungal, anti-inflammatory, α-glucosidase inhibitor, and cardiotonic activities of 2-pyridone-containing heterocycles obtained exclusively by an MCR. The discussion focuses on bioactivity data, synthetic approaches, plausible reaction mechanisms, and molecular docking simulations to facilitate comparison and underscore the applications of the 2-pyridone motif in drug discovery and medicinal chemistry. We also present our conclusions and outlook for the future.

Thermodynamic vs. Kinetic Control in Synthesis of O-Donor 2,5-Substituted Furan and 3,5-Substituted Pyrazole from Heteropropargyl Precursor

Elaboration of a convenient route towards donor-substituted pyrazoles from heteropropargyl precursors is challenging due to a number of thermodynamically favorable side reactions (e.g., acetylene-allene isomerization and Glaser homocoupling). In this work, Sonogashira cross-coupling conditions of 4-tert-butylphenyl propargyl ether with benzoyl chloride followed by tandem Michael addition/cyclocondensation with hydrazine into 3,5-disubstituted pyrazole (kinetic control), as well as cycloisomerization conditions of ketoacetylene intermediate into 2,5-disubstituted furan (thermodynamic control), were established through a variation of the catalyst loading, solvent polarity, excess of triethylamine, and time of reaction. During the optimization of process parameters, a number of by-products represented by a monophosphine binuclear complex (PPh₃PdI₂)₂ with two bridging iodine atoms and diyne were identified and isolated in the pure form. The quantum-chemical calculations and solution-state ¹H/¹³C NMR spectroscopy suggested that the 5(3)-(4-tert-butylphenyloxy)methoxy-3(5)-phenyl-1H-pyrazole exists in the tautomeric equilibrium in a polar methanol solvent and that individual tautomers could be characterized in case aprotic solvents employed. The pyrazole features a unique tetramer motif in the crystal phase formed by alternating 3(5)-phenyl-1H-pyrazole tautomers, which was stabilized by N-H···N bonds and stacking interactions of pyrazole rings, whereas pyrazole dimers were identified in the gas phase.