Novel imidazo[4,5-b]pyridine derived acrylonitriles: A combined experimental and computational study of their antioxidative potential

Imidazopyridine Family: Versatile and Promising Heterocyclic Skeletons for Different Applications

In recent years, there has been increasing attention focused on various products belonging to the imidazopyridine family; this class of heterocyclic compounds shows unique chemical structure, versatile optical properties, and diverse biological attributes. The broad family of imidazopyridines encompasses different heterocycles, each with its own specific properties and distinct characteristics, making all of them promising for various application fields. In general, this useful category of aromatic heterocycles holds significant promise across various research domains, spanning from material science to pharmaceuticals. The various cores belonging to the imidazopyridine family exhibit unique properties, such as serving as emitters in imaging, ligands for transition metals, showing reversible electrochemical properties, and demonstrating biological activity. Recently, numerous noteworthy advancements have emerged in different technological fields, including optoelectronic devices, sensors, energy conversion, medical applications, and shining emitters for imaging and microscopy. This review intends to provide a state-of-the-art overview of this framework from 1955 to the present day, unveiling different aspects of various applications. This extensive literature survey may guide chemists and researchers in the quest for novel imidazopyridine compounds with enhanced properties and efficiency in different uses.

Biological activity and computational analysis of novel acrylonitrile derived benzazoles as potent antiproliferative agents for pancreatic adenocarcinoma with antioxidative properties

Continuing our research into the anticancer properties of acrylonitriles, we present a study involving the design, synthesis, computational analysis, and biological assessment of novel acrylonitriles derived from methoxy, hydroxy, and N-substituted benzazole. Our aim was to examine how varying the number of methoxy and hydroxy groups, as well as the N-substituents on the benzimidazole core, influences their biological activity. The newly synthesized acrylonitriles exhibited strong and selective antiproliferative effects against the Capan-1 pancreatic adenocarcinoma cell line, with IC50 values ranging from 1.2 to 5.3 μM. Consequently, these compounds were further evaluated in three other pancreatic adenocarcinoma cell lines, while their impact on normal PBMC cells was also investigated to determine selectivity. Among these compounds, the monohydroxy-substituted benzimidazole derivative 27 emerged with the most profound and broad-spectrum anticancer antiproliferative activity being emerged as a promising lead candidate. Moreover, a majority of the acrylonitriles in this series exhibited significant antioxidative activity, surpassing that of the reference molecule BHT, as demonstrated by the FRAP assay (ranging from 3200 to 5235 mmolFe2+/mmolC). Computational analysis highlighted the prevalence of electron ionization in conferring antioxidant properties, with computed ionization energies correlating well with observed activities.

Novel acrylonitrile derived imidazo[4,5-b]pyridines as antioxidants and potent antiproliferative agents for pancreatic adenocarcinoma

We present the design, synthesis, computational analysis, and biological assessment of several acrylonitrile derived imidazo[4,5-b]pyridines, which were evaluated for their anticancer and antioxidant properties. Our aim was to explore how the number of hydroxy groups and the nature of nitrogen substituents influence their biological activity. The prepared derivatives exhibited robust and selective antiproliferative effects against several pancreatic adenocarcinoma cells, most markedly targeting Capan-1 cells (IC50 1.2-5.3 μM), while their selectivity was probed relative to normal PBMC cells. Notably, compound 55, featuring dihydroxy and bromo substituents, emerged as a promising lead molecule. It displayed the most prominent antiproliferative activity without any adverse impact on the viability of normal cells. Furthermore, the majority of studied derivatives also exhibited significant antioxidative activity within the FRAP assay, even surpassing the reference molecule BHT. Computational analysis rationalized the results by highlighting the dominance of the electron ionization for the antioxidant features with the trend in the computed ionization energies well matching the observed activities. Still, in trihydroxy derivatives, their ability to release hydrogen atoms and form a stable O-H⋯O•⋯H-O fragment upon the H• abstraction prevails, promoting them as excellent antioxidants in DPPH• assays as well.

Synthesis and Antiproliferative Activity of 2,6-Disubstituted Imidazo[4,5-b]pyridines Prepared by Suzuki Cross Coupling

A series of novel 2,6-diphenyl substituted imidazo[4,5-b]pyridines was designed and synthesized using optimized Suzuki cross coupling to evaluate their biological activity in vitro. The conditions of the Suzuki coupling were evaluated and optimized using a model reaction. To study the influence of the substituents on the biological activity, we prepared N-unsubstituted and N-methyl substituted imidazo[4,5-b]pyridines with different substituents at the para position on the phenyl ring placed at position 6 on the heterocyclic scaffold. Antiproliferative activity was determined on diverse human cancer cell lines, and the selectivity of compounds with promising antiproliferative activity was determined on normal peripheral blood mononuclear cells (PBMC). Pronounced antiproliferative activity was observed for p-hydroxy substituted derivatives 13 and 19, both displaying strong activity against most of the tested cell lines (IC50 1.45-4.25 μM). The unsubstituted N-methyl derivative 19 proved to be the most active derivative. There was a dose-dependent accumulation of G2/M arrested cells in several cancer cell lines after exposure to compound 19, implying a cell cycle-phase-specific mechanism of action. Additionally, the novel series of derivatives was evaluated for antiviral activity against a broad panel of viruses, yet the majority of tested compounds did not show antiviral activity.

Phenanthridine-pyrene conjugates as fluorescent probes for DNA/RNA and an inactive mutant of dipeptidyl peptidase enzyme

Two novel conjugate molecules were designed: pyrene and phenanthridine-amino acid units with a different linker length between the aromatic fragments. Molecular modelling combined with spectrophotometric experiments revealed that in neutral and acidic buffered water solutions conjugates predominantly exist in intramolecularly stacked conformations because of the π-π stacking interaction between pyrene and phenanthridine moieties. The investigated systems exhibited a pH-dependent excimer formation that is significantly red-shifted relative to the pyrene and phenanthridine fluorescence. While the conjugate with a short linker showed negligible spectrophotometric changes due to the polynucleotide addition, the conjugate with a longer and more flexible linker exhibited a micromolar and submicromolar binding affinity for ds-polynucleotides and inactivated a mutant of dipeptidyl peptidase enzyme E451A. Confocal microscopy revealed that the conjugate with the longer linker entered the HeLa cell membranes and blue fluorescence was visualized as the dye accumulated in the cell membrane.

Biological Activity of Amidino-Substituted Imidazo [4,5-b]pyridines

A series of cyano- and amidino-substituted imidazo[4,5-b]pyridines were synthesized using standard methods of organic synthesis, and their biological activity was evaluated. Biological evaluation included in vitro assessment of antiproliferative effects on a diverse selection of human cancer cell lines, antibacterial activity against chosen Gram-positive and Gram-negative bacterial strains, and antiviral activity on a broad panel of DNA and RNA viruses. The most pronounced antiproliferative activity was observed for compound 10, which contained an unsubstituted amidino group, and compound 14, which contained a 2-imidazolinyl amidino group; both displayed selective and strong activity in sub-micromolar inhibitory concentration range against colon carcinoma (IC₅₀ 0.4 and 0.7 μM, respectively). All tested compounds lacked antibacterial activity, with the exception of compound 14, which showed moderate activity against E. coli (MIC 32 μM). Bromo-substituted derivative 7, which contained an unsubstituted phenyl ring (EC₅₀ 21 μM), and para-cyano-substituted derivative 17 (EC₅₀ 58 μM) showed selective but moderate activity against respiratory syncytial virus (RSV).

Imidazo[4,5-b]pyridine derived tubulin polymerization inhibitors: Design, synthesis, biological activity in vitro and computational analysis

Imidazo[4,5-b]pyridine derived acrylonitriles were synthesized and explored for their in vitro antiproliferative effect on a diverse human cancer cell line panel. Three compounds, 20, 21 and 33, showed strong activity in the submicromolar range (IC₅₀ 0.2-0.6 μM), and were chosen for further biological experiments. Immunofluorescence staining and tubulin polymerization assays confirmed tubulin as the main target, but excluded its colchicine-binding site as a potential interacting unit. This was supported by the computational analysis, which revealed that the most potent ligands act on the extended colchicine site on the surface between interacting tubulin subunits, where they interfere with their polymerization and reveal pronounced antitumor properties. In addition, lead molecule 21 potently inhibited cancer cell migration, while it did not affect the viability of normal cells even at the highest concentration tested (100 µM).

Evaluation of Antioxidants Using Electrochemical Sensors: A Bibliometric Analysis

The imbalance of oxidation and antioxidant systems in the biological system can lead to oxidative stress, which is closely related to the pathogenesis of many diseases. Substances with antioxidant capacity can effectively resist the harmful damage of oxidative stress. How to measure the antioxidant capacity of antioxidants has essential application value in medicine and food. Techniques such as DPPH radical scavenging have been developed to measure antioxidant capacity. However, these traditional analytical techniques take time and require large instruments. It is a more convenient method to evaluate the antioxidant capacity of antioxidants based on their electrochemical oxidation and reduction behaviors. This review summarizes the evaluation of antioxidants using electrochemical sensors by bibliometrics. The development of this topic was described, and the research priorities at different stages were discussed. The topic was investigated in 1999 and became popular after 2010 and has remained popular ever since. A total of 758 papers were published during this period. In the early stages, electrochemical techniques were used only as quantitative techniques and other analytical techniques. Subsequently, cyclic voltammetry was used to directly study the electrochemical behavior of different antioxidants and evaluate antioxidant capacity. With methodological innovations and assistance from materials science, advanced electrochemical sensors have been fabricated to serve this purpose. In this review, we also cluster the keywords to analyze different investigation directions under the topic. Through co-citation of papers, important papers were analyzed as were how they have influenced the topic. In addition, the author’s country distribution and category distribution were also interpreted in detail. In the end, we also proposed perspectives for the future development of this topic.