The position of imidazopyridine and metabolic activation are pivotal factors in the antimutagenic activity of novel imidazo[1,2-a]pyridine derivatives

Bortoluzzi A, Sandjo LP, Braga AL, F. de Assis F. Highly Enantioselective Lewis Acid Catalyzed Conjugate Addition of Imidazo[1,2-a]pyridines to α,β-Unsaturated 2-Acylimidazoles under Mild Conditions

A highly enantioselective protocol for the conjugate addition of 2-arylimidazo[1,2-a]pyridines and other imidazo derivatives to α,β-unsaturated 2-acylimidazoles is described. The method uses a previously reported chiral-at-metal rhodium catalyst and provides the corresponding adducts in yields of 25-98% with enantioselectivities up to er > 99:1. Additionally, the transformation proceeds under mild conditions using ethanol as the solvent at room temperature.

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.

Imidazopyridine, a promising scaffold with potential medicinal applications and structural activity relationship (SAR): recent advances

Imidazopyridine scaffold has gained tremendous importance over the past few decades. Imidazopyridines have been expeditiously used for the rationale design and development of novel synthetic analogs for various therapeutic disorders. A wide variety of imidazopyridine derivatives have been developed as potential anti-cancer, anti-diabetic, anti-tubercular, anti-microbial, anti-viral, anti-inflammatory, central nervous system (CNS) agents besides other chemotherapeutic agents. Imidazopyridine heterocyclic system acts as a key pharmacophore motif for the identification and optimization of lead structures to increase medicinal chemistry toolbox. The present review highlights the medicinal significances of imidazopyridines for their rationale development as lead molecules with improved therapeutic efficacies. This review further emphasis on the structure-activity relationships (SARs) of the various designed imidazopyridines to establish a relationship between the key structural features versus the biological activities.Communicated by Ramaswamy H. Sarma.

Electrochemically Promoted [3 + 2] Annulation of Imidazo[1,2-a]pyridine with Alkynes

The efficient electrochemically promoted [3 + 2] annulation of imidazo[1,2-a]pyridines with alkynes using traceless electrons as green reagents has been developed, leading to the synthesis of a large class of polycyclic heteroaromatics in good yields with a broad substrate scope under mild and green conditions. The scaled-up experiment, follow-up procedures, and potential biological applications show the practicability and feasibility of the electrochemical method.

Imidazopyridine–fluoride interaction: solvent-switched AIE effects via S⋯O conformational locking

Imidazopyridine-based carboxamide exhibiting the aggregation-induced emission phenomenon works effectively in fluoride ion detection through H-bond interaction and subsequent deprotonation.

A Novel Imidazo[1,2-a]pyridine Compound Reduces Cell Viability and Induces Apoptosis of HeLa Cells by p53/Bax-Mediated Activation of Mitochondrial Pathway

BACKGROUND

Despite emerging research on new treatment strategies, chemotherapy remains one of the most important therapeutic modalities for cancers. Imidazopyridines are important targets in organic chemistry and are worthy of attention given their numerous applications.

OBJECTIVE

To design and synthesize a novel series of imidazo[1,2-a]pyridine-derived compounds and investigate their antitumor effects and the underlying mechanisms.

METHODS

Imidazo[1,2-a]pyridine-derived compounds were synthesized with new strategies and conventional methods. The antitumor activities of the new compounds were evaluated by MTT assay. Flow cytometry and immunofluorescence were performed to examine the effects of the most effective antiproliferative compound on cell apoptosis. Western blot analysis was used to assess the expression of apoptotic proteins.

RESULTS

Fifty-two new imidazo[1,2-a]pyridine compounds were designed and successfully synthesized. The compound, 1-(imidazo[1,2-a]pyridin-3-yl)-2-(naphthalen-2-yl)ethane-1,2-dione, named La23, showed high potential for suppressing the viability of HeLa cells (IC50 15.32 μM). La23 inhibited cell proliferation by inducing cell apoptosis, and it reduced the mitochondrial membrane potential of HeLa cells. Moreover, treatment with La23 appeared to increase the expression of apoptotic-related protein P53, Bax, cleaved caspase-3, and cytochrome c at a low concentration range.

CONCLUSION

The novel imidazo[1,2-a]pyridine compound, La23, was synthesized and suppressed cell growth by inducing cell apoptosis via the p53/Bax mitochondrial apoptotic pathway.

Antigenotoxic and Antimutagenic Effects of Andrographis paniculata, a Traditional Medicinal Herb against Genotoxicity of Cyclophosphamide: An In Vitro Study on Human Peripheral Lymphocytes

Andrographis paniculata (family: Acanthaceae) is a medicinal herb—used in Indian system of medicine (Ayurveda, Siddha, and Unani), traditional and folk systems to treat various illnesses. This study examined the phytochemical constituents of ethanol extract from A. paniculata and its protective effect against genotoxicity caused by cyclophosphamide (CPA). Phytochemical screening and estimation of total phenolic content were analyzed using standard methods. The bioactive components from the ethanol extract of A. paniculata (EAP) were analyzed using gas chromatography-mass spectrometry. To investigate the protective effect of EAP against CPA-induced genotoxicity, human peripheral lymphocyte cultures were used. To test the antigenotoxic and antimutagenic effects of EAP, lymphocytes were treated with different concentrations of extract (50∼250 mg/mL) alone and co-treated along with CPA+EAP for 48 h. The cells were analyzed for structural chromosomal aberrations (CAs) and sister chromatid exchanges (SCEs) in control, CPA treated, and CPA+ EAP co-treated lymphocytes. Results of the study revealed that the lymphocyte cultures which had 48 h continuous exposure to EAP (50∼250 mg/mL) did not show any significant changes in CAs and SCE frequencies. These results substanti-ate the antimutagenic nature of the extract. Furthermore, the lymphocytes co-treated with CPA along with extract showed a significant reduction in CAs (reduced from 26.50±2.50% to 11.00±1.00%) and SCEs (reduced from 9.92±0.63 per cell to 4.56±0.18 per cell). These results suggest that A. paniculata is protective against CPA induced genotoxicity and put forward its possible use as a supplement with chemotherapeutic drugs.

Rh(III)-Catalyzed Tandem Bicyclization of 2-Arylimidazo[1,2-a]pyridines with Cyclic Enones for the Construction of Bridged Scaffolds

An efficient Rh(III)-catalyzed bicyclization of 2-arylimidazo[1,2-a]pyridine with cyclic enones has been developed for the synthesis of bridged imidazopyridine derivatives in excellent yields up to 95%. The reaction proceeds through a sequential conjugate addition of ortho-C-H bond of aryl group followed by an intramolecular C3-alkylation of imidazopyridine ring in a highly regioselective manner.

Catalyst free, C-3 functionalization of imidazo[1,2-a]pyridines to rapidly access new chemical space for drug discovery efforts

Multicomponent reactions (MCRs) are robust tools for the rapid synthesis of complex, small molecule libraries for use in drug discovery and development. By utilizing MCR chemistry, we developed a protocol to functionalize the C-3 position of imidazo[1,2-a]pyridine through a three component, decarboxylation reaction involving imidazo[1,2-a]pyridine, glyoxalic acid, and boronic acid.

Synthesis and anticonvulsant activity of phenoxyacetyl derivatives of amines, including aminoalkanols and amino acids

A series of 17 new phenoxyacetamides has been prepared via multistep chemical synthesis as a continuation of the research carried out by our group on di- and tri-substituted phenoxyalkyl and phenoxyacetyl derivatives of amines. The obtained compounds vary in an amide component, for example aminoalkanol or (un)modified amino acid moieties were introduced. The structures of selected products were confirmed by means of crystallographic methods. All 17 compounds were the subject of preliminary screening for potential anticonvulsant activity (MES, 6 Hz and/or scMET tests) and neurotoxicity (rotarod) in mice after intraperitoneal administration, while several active compounds were subsequently examined in additional models (e.g. MES and rotarod - rats, p.o. or i.p., hippocampal kindling - rats, i.p.). Finally, safety studies (cytotoxicity and cell proliferation assays on astrocytes, metabolic stability assessment, mutagenicity evaluation) were performed for several active compounds, including the most promising one (R-(-)-2-(2,6-dimethylphenoxy)-N-(1-hydroxypropan-2-yl)acetamide, MES ED₅₀ = 12.00 mg per kg b.w., rats, p.o.).

Amelioration of the cyclophosphamide induced genotoxic damage in mice by the ethanolic extract of Equisetum arvense

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Plants like E. arvense posess not only nutritional value but therapeutic value as well.

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CPA is an important chemotherapeutic agent but is associated with various mutagenic and other toxic side effects.

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Ethanolic extract of the plant has immense protective effect against the genotoxic damage induced by the cyclophosphamide.

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GC–MS analysis of the extract shows various important phyto components which may be associated with its antimutagenic property.

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Plant can be used in cancer as a chemopreventive agent or even as a coadjuvant to chemotherapy to reduce the side effects associated with it.

In the present study, we evaluated the potential of the plant E. arvense against the cytotoxic and mutagenic effects induced by cyclophosphamide (chemotherapeutic agent) in the bone marrow cells of mice using the Chromosome assay (CA) and Mitotic index (MI) in vivo as the biomarkers. The study was performed following 3 protocols: pre-treatment, simultaneous treatment and post-treatment with the ethanolic extract of the plant. The results demonstrated that the plant extract was not cytotoxic and mutagenic and has a protective effect against the mutagenicity induced by cyclophosphamide in pre, simultaneous and post treatments and against its cytotoxicity as well. Because of its ability to prevent chromosomal damage, E. arvense is likely to open an interesting field concerning its possible use in clinical applications, most importantly in cancer as a chemopreventive agent or even as a coadjuvant to chemotherapy to reduce the side effects associated with it.

Direct C–H heteroarylation by an acenaphthyl-based α-diimine palladium complex: improvement of the reaction efficiency for bi(hetero)aryls under aerobic conditions

A bulky ancenaphthyl skeleton-based α-diimine palladium complex has been developed, which exhibited high reactivity for direct heteroarylation of heteroaryl bromides under aerobic conditions with a broad substrate scope.

In vitro mutagenic, antimutagenic, and antioxidant activities evaluation and biotransformation of some bioactive 4-substituted 1-(2-methoxyphenyl)piperazine derivatives

In vitro mutagenic, antimutagenic, and antioxidant potency evaluation and biotransformation of six novel 4-substituted 1-(2-methoxyphenyl)piperazine derivatives demonstrating antidepressant-like activity were investigated. Mutagenic and antimutagenic properties were assessed using the Ames test; free radical scavenging activity was evaluated with 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay and biotransformation was performed with liver microsomes. It was found that all tested compounds are not mutagenic in bacterial strains TA100 and TA1535 and exhibit antimutagenic effects in the Ames test. Noteworthy, compounds possessing propyl linker between phenoxyl and N-(2-methoxyphenyl)piperazine displayed more pronounced antimutagenic properties than derivatives with ethoxyethyl linker. Additionally, compounds 2 and 6 in vitro biotransformation showed that primarily their hydroxylated or O-dealkylated metabolites are formed. Some of the compounds exhibited intrinsic clearance values lower than those reported previously for antidepressant imipramine. To sum up, the results of the present study might represent a valuable step in designing and planning future studies with piperazine derivatives.

An unprecedented Pd-catalyzed decarboxylative coupling reaction of aromatic carboxylic acids in aqueous medium under air: synthesis of 3-aryl-imidazo[1,2-a]pyridines from aryl chlorides

An efficient and practical protocol for palladium-catalyzed decarboxylative arylation of imidazo[1,2-a]pyridine-3-carboxylic acids with aryl chlorides has been developed. Note that the reaction could proceed smoothly without an additive in aqueous medium under an ambient atmosphere, and the addition of H2O could effectively promote the decarboxylative arylation. Particularly noteworthy is that these results represent the first examples of Pd-catalyzed decarboxylative coupling reactions of (hetero) aromatic carboxylic acids in aqueous medium under air, and the first successful examples of the synthesis of 3-aryl-imidazo[1,2-a]pyridines using cheap, diverse aryl chlorides and heteroaryl chlorides as the starting materials.

A facile one-pot multi-component synthesis of novel adamantine substituted imidazo[1,2-a]pyridine derivatives: identification and structure–activity relationship study of their anti-HIV-1 activity

A series of adamantine substituted imidazo[1,2-a]pyridine derivatives were developed through a one-pot multi-component Groebke–Blackburn–Bienaymé reaction, among them several compounds were identified to be the potent inhibitors against HIV-1 cells.

Metal-free, efficient hydrazination of imidazo[1,2-a]pyridine with diethyl azodicarboxylate in neutral media

The first example of metal-free regioselective hydrazination of imidazo[1,2-a]pyridine with diethyl azodicarboxylate is accomplished. This procedure is chemically appealing due to the high degree of functional group tolerance and efficiency in expanding the molecular diversity.

Efficient access to 2,3-diarylimidazo[1,2-a]pyridines via a one-pot, ligand-free, palladium-catalyzed three-component reaction under microwave irradiation

An expeditious one-pot, ligand-free, Pd(OAc)2-catalyzed, three-component reaction for the synthesis of 2,3-diarylimidazo[1,2-a]pyridines was developed under microwave irradiation. With the high availability of commercial reagents and great efficiency in expanding molecule diversity, this methodology is superior to the existing procedures for the synthesis of 2,3-diarylimidazo[1,2-a]pyridines analogues.

Preliminary assessment of mutagenic and anti-mutagenic potential of some aminoalkanolic derivatives of xanthone by use of the Vibrio harveyi assay

The Vibrio harveyi assay was used to evaluate mutagenic and anti-mutagenic effects of four new aminoalkanolic derivatives of xanthone with anticonvulsant activity, to select the potentially safe compounds for further in vivo studies in animal models. The study showed that at a concentration of 40 ng/ml the test compounds were not mutagenic. Additionally, two of the investigated compounds, namely the (R,S)-N-methyl-1-amino-2-propanol derivative of 6-methoxyxanthone (compound III) and the (R)-N-methyl-2-amino-1-butanol derivative of 7-chloroxanthone (compound IV) were strong inhibitors of the mutagenicity induced by 4-nitroquinoline-N-oxide (4-NQO) in V. harveyi strains BB7M and BB7XM. The inhibition percentages for compound IV were 49 (in BB7M) and 69 (in BB7XM), whereas for compound III these percentages were 47 (in BB7M) and 42 (in BB7XM), respectively. The present study demonstrates that four bioactive derivatives of xanthone display no mutagenic activity in the V. harveyi assay. In addition, compounds III and IV demonstrated considerable anti-mutagenic activity in this test. Based on the results obtained here, these compounds could be selected for further studies in animal models, while compounds III and IV should be tested further for their anti-mutagenic properties.

Antimutagenic compounds and their possible mechanisms of action

Mutagenicity refers to the induction of permanent changes in the DNA sequence of an organism, which may result in a heritable change in the characteristics of living systems. Antimutagenic agents are able to counteract the effects of mutagens. This group of agents includes both natural and synthetic compounds. Based on their mechanism of action among antimutagens, several classes of compounds may be distinguished. These are compounds with antioxidant activity; compounds that inhibit the activation of mutagens; blocking agents; as well as compounds characterized with several modes of action. It was reported previously that several antitumor compounds act through the antimutagenic mechanism. Hence, searching for antimutagenic compounds represents a rapidly expanding field of cancer research. It may be observed that, in recent years, many publications were focused on the screening of both natural and synthetic compounds for their beneficial muta/antimutagenicity profile. Thus, the present review attempts to give a brief outline on substances presenting antimutagenic potency and their possible mechanism of action. Additionally, in the present paper, a screening strategy for mutagenicity testing was presented and the characteristics of the most widely used antimutagenicity assays were described.