Synthesis and therapeutic potential of imidazole containing compounds

Regioselective Synthesis of 2-Aryl-5-cyano-1-(2-hydroxyaryl)-1H-imidazole-4-carboxamides Self-Assisted by a 2-Hydroxyaryl Group

The reactivity of the diaminomaleonitrile-based imines containing hydroxyphenyl substituents with diverse aromatic aldehydes has been explored for the synthesis of novel highly substituted nitrogen heterocycles, which are considered privileged scaffolds in drug discovery. We report here a simple and efficient method for the regiocontrolled synthesis of a variety of 2-aryl-5-cyano-1-(2-hydroxyaryl)-1H-imidazole-4-carboxamides from 2-hydroxybenzylidene imines and aromatic aldehydes. Computational studies on the reaction path revealed that the regioselectivity of the reaction toward the formation of imidazole derivatives instead of 1,2-dihydropyrazines, most likely via a diaza-Cope rearrangement, is driven by the 2-hydroxyaryl group in the scaffold. The latter group promotes the intramolecular abstraction and protonation process in the cycloadduct intermediate, triggering the evolution of the reaction toward the formation of imidazole derivatives.

1-Mesityl-3-(3-Sulfonatopropyl) Imidazolium Protects Against Oxidative Stress and Delays Proteotoxicity in C. elegans

Due to the increase in life expectancy worldwide, age-related disorders such as neurodegenerative diseases (NDs) have become more prevalent. Conventional treatments comprise drugs that only attenuate some of the symptoms, but fail to arrest or delay neuronal proteotoxicity that characterizes these diseases. Due to their diverse biological activities, imidazole rings are intensively explored as powerful scaffolds for the development of new bioactive molecules. By using C. elegans, our work aims to explore novel biological roles for these compounds. To this end, we have tested the in vivo anti-proteotoxic effects of imidazolium salts. Since NDs have been largely linked to impaired antioxidant defense mechanisms, we focused on 1-Mesityl-3-(3-sulfonatopropyl) imidazolium (MSI), one of the imidazolium salts that we identified as capable of improving iron-induced oxidative stress resistance in wild-type animals. By combining mutant and gene expression analysis we have determined that this protective effect depends on the activation of the Heat Shock Transcription Factor (HSF-1), whereas it is independent of other canonical cytoprotective molecules such as abnormal Dauer Formation-16 (DAF-16/FOXO) and Skinhead-1 (SKN-1/Nrf2). To delve deeper into the biological roles of MSI, we analyzed the impact of this compound on previously established C. elegans models of protein aggregation. We found that MSI ameliorates β-amyloid-induced paralysis in worms expressing the pathological protein involved in Alzheimer’s Disease. Moreover, this compound also delays age-related locomotion decline in other proteotoxic C. elegans models, suggesting a broad protective effect. Taken together, our results point to MSI as a promising anti-proteotoxic compound and provide proof of concept of the potential of imidazole derivatives in the development of novel therapies to retard age-related proteotoxic diseases.

Viability of Glioblastoma Cells and Fibroblasts in the Presence of Imidazole-Containing Compounds

The naturally occurring dipeptide carnosine (β-alanyl-L-histidine) specifically attenuates tumor growth. Here, we ask whether other small imidazole-containing compounds also affect the viability of tumor cells without affecting non-malignant cells and whether the formation of histamine is involved. Patient-derived fibroblasts and glioblastoma cells were treated with carnosine, L-alanyl-L-histidine (LA-LH), β-alanyl-L-alanine, L-histidine, histamine, imidazole, β-alanine, and L-alanine. Cell viability was assessed by cell-based assays and microscopy. The intracellular release of L-histidine and formation of histamine was investigated by high-performance liquid chromatography coupled to mass spectrometry. Carnosine and LA-LH inhibited tumor cell growth with minor effects on fibroblasts, and L-histidine, histamine, and imidazole affected viability in both cell types. Compounds without the imidazole moiety did not diminish viability. In the presence of LA-LH but not in the presence of carnosine, a significant rise in intracellular amounts of histidine was detected in all cells. The formation of histamine was not detectable in the presence of carnosine, LA-LH, or histidine. In conclusion, the imidazole moiety of carnosine contributes to its anti-neoplastic effect, which is also seen in the presence of histidine and LA-LH. Despite the fact that histamine has a strong effect on cell viability, the formation of histamine is not responsible for the effects on the cell viability of carnosine, LA-LH, and histidine.

Turn on Fluorescence Sensing of Zn2+ Based on Fused Isoindole-Imidazole Scaffold

Optical chemosensors caused a revolution in the field of sensing due to their high specificity, sensitivity, and fast detection features. Imidazole derivatives have offered promising features in the literature as they bear suitable donor/acceptor groups for the selective analytes in the skeleton. In this work, an isoindole-imidazole containing a Schiff base chemosensor (1-{3-[(2-Diethylamino-ethylimino)-methyl]-2-hydroxy-5-methyl-phenyl}-2H-imidazo[5,1-a]isoindole-3,5-dione) was designed and synthesized. The complete sensing phenomena have been investigated by means of UV-Vis, fluorescence, lifetime measurement, FT-IR, NMR and ESI-MS spectroscopic techniques. The optical properties of the synthesized ligand were investigated in 3:7 HEPES buffer:DMSO medium and found to be highly selective and sensitive toward Zn²⁺ ion through a fluorescence turn-on response with detection limit of 0.073 μm. Furthermore, this response is effective in gel form also. The competition studies reveal that the response of the probe for Zn²⁺ ion is unaffected by other relevant metal ions. The stoichiometric binding study was performed utilizing Job’s method which indicated a 1:1 sensor–Zn²⁺ ensemble. Computational calculations were performed to pinpoint the mechanism of sensing.

The reaction of acetaldehyde, glyoxal, and ammonia to yield 2-methylimidazole: thermodynamic and kinetic analyses of the mechanism

The most thermodynamically and kinetically favorable pathways for the formation of 2-methylimidazole (2MI) in the reaction of glyoxal and acetaldehyde with ammonia in aqueous solution have been determined. The formation of 2MI proceeds through a number of successive intermediates of acyclic and cyclic structures, and the most favorable route (thermodynamically and kinetically) for the formation of the imidazole ring is the condensation of amine intermediates, in contrast to the existing concepts of imine structures. The limiting stage is the stage of cyclization involving the intramolecular attack by the amino group of the precyclic intermediate on the carbon atom bound to the hydroxyl group with the simultaneous release of a water molecule according to the S_N2 mechanism. Further stages of stepwise dehydration lead to the formation of a cyclic diazine, the intramolecular migration of the proton of the tertiary carbon atom to the nitrogen atom of which completes the formation of 2MI. Experimental studies on the effect of the order of mixing of initial reagents on the 2MI yield confirmed the quantum-chemically substantiated favorable pathway for the formation of 2MI during the interaction of amine intermediates, and also revealed that the selectivity of the 2MI formation is achieved by successive mixing of acetaldehyde with ammonia until the formation of hydroxyamine products and their further interaction with glyoxal.

Synthesis and Antimicrobial, Antiplatelet, and Anticoagulant Activities of New Isatin Deivatives Containing a Hetero-Fused Imidazole Fragment

A series of isatin derivatives containing an adenine or theophylline fragment have been synthesized. The corresponding N′-[2-(trimethylammonio)acetyl] and N′-(2-pyridinioacetyl) hydrazones have been found to exhibit neither cytotoxicity nor hemotoxicity. Quaternary salts based on adenine derivatives of 5-methyl- and 5-ethylisatins showed the highest antiplatelet activity which exceeded the activity of acetylsalicylic acid by a factor of 1.5.

Crystal structure of (E)-(4-imidazol-1-yl-phenyl)-(2-methoxy-benzylidene)-amine monohydrate, C17H17N3O2

C17H17N3O2, monoclinic, P21/c (no. 14), a = 10.655(5) Å, b = 5.056(5) Å, c = 28.712 Å, β = 99.034(1)°, V = 1527.6(17) Å3, Z = 4, R gt (F) = 0.0520, wR ref(F 2) = 0.1611, T = 298(2) K.

Utility of arylglyoxal hydrates in synthesis of 4-aroyl-[1,3,5]triazino[1,2-a]benzimidazol-2(1H)-imines and 5-aryl-2-phenyl-4H-imidazol-4-imines

Nucleophilic substitution reaction for arylglyoxal hydrates (AGs-hydrate) was studied via their reaction with some mono- and multi-nucleophilic reagents in the presence of sodium ethoxide as basic catalyst. Thus, reaction of phenylglyoxal hydrate (1a) with hydrogen sulfide and/or ammonium acetate afforded the corresponding 2-hydroxy-2-mercapto-1-phenylethanone (2) and 2-oxo-2-phenylethanimidamide (3), respectively. Heterocyclization reaction of AGs-hydrate 1a-f with 1-(1H-benzimidazol-2-yl)guanidine (4) gave 4-aroyl-[1,3,5]triazino[1,2-a]benzimidazol-2(1H)-imines 5a-f. Also, a series of 5-aryl-2-phenyl-4H-imidazol-4-imines 7a-d was synthesized via one-pot multicomponent reaction of AGs-hydrate 1a-d, benzonitrile (6) and ammonium acetate. Imidazole-4-imines 7a-d can be also prepared using other route via multicomponent reaction of AGs-hydrate 1a-d, benzenecarboximidamide acetate (8) and ammonium acetate.

Recent development of imidazole derivatives as potential anticancer agents

Cancer, one of the key health problems globally, is a group of related diseases that share a number of characteristics primarily the uncontrolled growth and invasive to surrounding tissues. Chemotherapy is one of the ways for the treatment of cancer which uses one or more anticancer agents as per chemotherapy regimen. Limitations of most anticancer drugs due to a variety of reasons such as serious side effects, drug resistance, lack of sensitivity and efficacy etc. generate the necessity towards the designing of novel anticancer lead molecules. In this regard, the synthesis of biologically active heterocyclic molecules is an appealing research area. Among heterocyclic compounds, nitrogen containing heterocyclic molecules has fascinated tremendous consideration due to broad range of pharmaceutical activity. Imidazoles, extensively present in natural products as well as synthetic molecules, have two nitrogen atoms, and are five membered heterocyclic rings. Because of their countless physiological and pharmacological characteristics, medicinal chemists are enthused to design and synthesize new imidazole derivatives with improved pharmacodynamic and pharmacokinetic properties. The aim of this present chapter is to discuss the synthesis, chemistry, pharmacological activity, and scope of imidazole-based molecules in anticancer drug development. Finally, we have discussed the current challenges and future perspectives of imidazole-based derivatives in anticancer drug development.

Visible light photocatalysis in the synthesis of pharmaceutically relevant heterocyclic scaffolds

Visible light and photoredox catalysis have emerged as a powerful and long-lasting tool for organic synthesis, demonstrating the importance of a variety of chemical bond formation methods.

Synthesis, Spectroscopic, Thermal, and Catalytic Properties of Eight New Complexes of Metal(II) Formates or Propionates with Imidazole; Relationship between the Carbon Chain Length and Catalytic Activity

In one of our previously published articles, we reported the synthesis, spectroscopic, thermal, and catalytic properties of four new M(II) acetate (where M = Co, Ni, Cu, Zn) complexes with imidazole. Presented compounds exhibited activity in the reaction on catalytic oxidation of styrene. In this study we have synthesized and investigated properties of analogous compounds, however using formates or propionates of mentioned metal cations instead of acetates. Such an approach allowed us to draw valuable conclusions concerning the relationship between the carbon chain length and catalytic activity, which is an important factor for catalyst modeling. Synthesized compounds have been thoroughly investigated using appropriate analytic techniques: AAS (Atomic Absorption Spectrometry), FTIR (Fourier-Transform Infrared Spectroscopy), and TGA (Thermogravimetric Analysis). Catalytic properties have been studied under the same previous conditions, using GC-FID (GC-chromatograph equipped with FID detector).

Anticancer Activity of Natural and Synthetic Chalcones

Cancer is a condition caused by many mechanisms (genetic, immune, oxidation, and inflammatory). Anticancer therapy aims to destroy or stop the growth of cancer cells. Resistance to treatment is theleading cause of the inefficiency of current standard therapies. Targeted therapies are the most effective due to the low number of side effects and low resistance. Among the small molecule natural compounds, flavonoids are of particular interest for theidentification of new anticancer agents. Chalcones are precursors to all flavonoids and have many biological activities. The anticancer activity of chalcones is due to the ability of these compounds to act on many targets. Natural chalcones, such as licochalcones, xanthohumol (XN), panduretin (PA), and loncocarpine, have been extensively studied and modulated. Modification of the basic structure of chalcones in order to obtain compounds with superior cytotoxic properties has been performed by modulating the aromatic residues, replacing aromatic residues with heterocycles, and obtaining hybrid molecules. A huge number of chalcone derivatives with residues such as diaryl ether, sulfonamide, and amine have been obtained, their presence being favorable for anticancer activity. Modification of the amino group in the structure of aminochalconesis always favorable for antitumor activity. This is why hybrid molecules of chalcones with different nitrogen hetercycles in the molecule have been obtained. From these, azoles (imidazole, oxazoles, tetrazoles, thiazoles, 1,2,3-triazoles, and 1,2,4-triazoles) are of particular importance for the identification of new anticancer agents.

TMSOTf-catalyzed synthesis of trisubstituted imidazoles using hexamethyldisilazane as a nitrogen source under neat and microwave irradiation conditions

In the process of drug discovery and development, an efficient and expedient synthetic method for imidazole-based small molecules from commercially available and cheap starting materials has great significance. Herein, we developed a TMSOTf-catalyzed synthesis of trisubstituted imidazoles through the reaction of 1,2-diketones and aldehydes using hexamethyldisilazane as a nitrogen source under microwave heating and solvent-free conditions. The chemical structures of representative trisubstituted imidazoles were confirmed using X-ray single-crystal diffraction analysis. This synthetic method has several advantages including the involvement of mild Lewis acid, being metal- and additive-free, wide substrate scope with good to excellent yields and short reaction time. Furthermore, we demonstrate the application of the methodology in the synthesis of biologically active imidazole-based drugs.

Trisubstituted imidazoles are synthesized efficiently from the readily available 1,2-diketones and aldehydes using hexamethyldisilazane as a new and stable nitrogen source under TMSOTf-catalysis system, microwave heating and solvent-free conditions.

Imidazoles as Potential Anticancer Agents: An Update on Recent Studies

Nitrogen-containing heterocyclic rings are common structural components of marketed drugs. Among these heterocycles, imidazole/fused imidazole rings are present in a wide range of bioactive compounds. The unique properties of such structures, including high polarity and the ability to participate in hydrogen bonding and coordination chemistry, allow them to interact with a wide range of biomolecules, and imidazole-/fused imidazole-containing compounds are reported to have a broad spectrum of biological activities. This review summarizes recent reports of imidazole/fused imidazole derivatives as anticancer agents appearing in the peer-reviewed literature from 2018 through 2020. Such molecules have been shown to modulate various targets, including microtubules, tyrosine and serine-threonine kinases, histone deacetylases, p53-Murine Double Minute 2 (MDM2) protein, poly (ADP-ribose) polymerase (PARP), G-quadraplexes, and other targets. Imidazole-containing compounds that display anticancer activity by unknown/undefined mechanisms are also described, as well as key features of structure-activity relationships. This review is intended to provide an overview of recent advances in imidazole-based anticancer drug discovery and development, as well as inspire the design and synthesis of new anticancer molecules.

Design and fabrication of photoactive imidazole-based poly(ether-imide)s and a polyimide/HBP-modified SiO2 composite: toward high heat-resistance, antimicrobial activity and removal of heavy metal ions

This article describes the synthesis and properties of novel imidazole-based aromatic polyimides (PIs) containing bulky groups from direct polycondensation of two diamines with 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA) and (hexafluoroisopropylidene)diphthalic anhydride (6FDA). The structure–property relationship of the prepared samples was fully determined via FT-IR, ¹H and ¹³C NMR and elemental analysis (CHN) techniques. The inherent viscosity values of the polyimides ranged from 0.51 to 0.73 dL g⁻¹. These PIs showed glass transition temperatures ranging from 273 to 306 °C, and 10% mass loss temperatures within the range of 478–504 °C in a N₂ atmosphere. High transparency with a UV-visible absorption cut-off wavelength was found to range between 285 and 300 nm. Good antimicrobial activity can be correlated with the presence of xanthene and imidazole units into the main structure of PIs. Next, SiO₂ nanoparticles as inorganic nanoparticles were added to one of the synthesized polyimides (BTDA-PIb), causing changes in the attributes of both the nanoparticles and PI. The data obtained from examining the properties of the prepared BTDA-PIb/HBP@SiO₂ demonstrated increased heat resistance, photoluminescence intensity, and antimicrobial inhibition compared to pure PI. Also, in this article, the polymeric samples as adsorbents were evaluated for extraction of heavy metal ions (Hg²⁺ and Co²⁺) from water sources.

Novel thermostable, photoactive, and solvable poly(ether-imide)s containing imidazole-based pendant groups and a BTDA-PIb/HBP@SiO₂ composite were synthesized and used due to their antimicrobial activity and as an adsorbent to remove heavy metal ions.

Tuning Anti-Biofilm Activity of Manganese(II) Complexes: Linking Biological Effectiveness of Heteroaromatic Complexes of Alcohol, Aldehyde, Ketone, and Carboxylic Acid with Structural Effects and Redox Activity

The constantly growing resistance of bacteria to antibiotics and other antibacterial substances has led us to an era in which alternative antimicrobial therapies are urgently required. One promising approach is to target bacterial pathogens using metal complexes. Therefore, we investigated the possibility of utilizing series of manganese(II) complexes with heteroaromatic ligands: Alcohol, aldehyde, ketone, and carboxylic acid as inhibitors for biofilm formation of Pseudomonas aeruginosa. To complete the series mentioned above, Mn-dipyCO-NO₃ with dipyridin-2-ylmethanone (dipyCO) was isolated, and then structurally (single-crystal X-ray analysis) and physicochemically characterized (FT-IR, TG, CV, magnetic susceptibility). The antibacterial activity of the compounds against representative Gram-negative and Gram-positive bacteria was also evaluated. It is worth highlighting that the results of the cytotoxicity assays performed (MTT, DHI HoloMonitorM4) indicate high cell viability of the human fibroblast (VH10) in the presence of the Mn(II) complexes. Additionally, the inhibition effect of catalase activity by the complexes was studied. This paper focused on such aspects as studying different types of intermolecular interactions in the crystals of the Mn(II) complexes as well as their possible effect on anti-biofilm activity, the structure-activity relationship of the Mn(II) complexes, and regularity between the electrochemical properties of the Mn(II) complexes and anti-biofilm activity.