Development of drugs based on imidazole and benzimidazole bioactive heterocycles: recent advances and future directions

Investigating the therapeutic promise of drug-repurposed-loaded nanocarriers: A pioneering strategy in advancing colorectal cancer treatment

Globally, colorectal cancer is a major health problem that ranks in third place in terms of occurrence and second in terms of mortality worldwide. New cases increase annually, with the absence of effective therapies, especially for metastatic colorectal cancer, emphasizing the need for novel therapeutic approaches. Although conventional treatments are commonly used in oncotherapy, their success rate is low, which leads to the exploration of novel technologies. Recent efforts have focused on developing safe and efficient cancer nanocarriers. With their nanoscale properties, nanocarriers have the potential to utilize internal metabolic modifications amid cancer and healthy cells. Drug repurposing is an emerging strategy in cancer management as it is a faster, cheaper, and safer method than conventional drug development. However, most repurposed drugs are characterized by low-key pharmacokinetic characteristics, such as poor aqueous solubility, permeability, retention, and bioavailability. Nanoparticles formulations and delivery have expanded over the past few decades, creating opportunities for drug repurposing and promises as an advanced cancer modality. This review provides a concise and updated overview of colorectal cancer treatment regimens and their therapeutic limitations. Furthermore, the chemotherapeutic effect of various FDA-approved medications, including statins, non-steroidal anti-inflammatory drugs, antidiabetic and anthelmintic agents, and their significance in colorectal cancer management. Along with the role of various nanocarrier systems in achieving the desired therapeutic outcomes of employing these redefined drugs.

Sustainable and Advanced LED-Implanted Microfluidic Photoreactor with Coupled Optical Fiber Enabling Efficient Photocatalytic Synthesis Beside Online Reaction Progress Monitoring

The conventional methods for the photoinduced synthesis of benzimidazoles may need further improvement regarding a safer and energy-efficient synthesis platform with in-process monitoring for maximum yield within a much reduced reaction time. This work describes the use of a novel optofluidic Lab-on-a-Chip technology for safer, energy-efficient, and expedited synthesis of benzimidazole derivatives in excellent yields along with real-time quantitative measurement during product formation. This innovative method involves synthesis within LED-embedded microfluidic reactors, allowing for rapid synthesis of benzimidazole derivatives via photoinduced condensation cyclization reactions of aryl aldehydes and o-phenylenediamines using a Rose Bengal/fluorescein photocatalyst. It results in good to excellent yields (85-94%) in a notably shorter period of time (10 min) as compared to that for the batch protocol reaction (2-3 h). The incorporation of a reaction-monitoring microfluidic device precisely connected to the microfluidic reactor (microreactor) unit successfully avoids interference from light sources, ensuring consistent UV-vis spectroscopic observations of the produced benzimidazole derivatives. This LED-embedded microfluidic device's capability of photoinduced synthesis, along with real-time spectroscopic analysis, represents a promising breakthrough in organic synthesis. The proposed approach minimizes the potential for accidents, prevents waste of chemicals, maximizes atom economy, and designs an energy-efficient synthesis route, along with real-time in-process monitoring.

Curcumol derivatives exhibit ameliorating effects on lipopolysaccharide-induced acute lung injury: Synthesis, biological evaluation, structure-activity relationship and action mechanism

Acute lung injury (ALI) is an intricate clinical disease marked by high mortality and a sudden start. Currently, although there are no specific therapeutics for ALI, the administration of anti-inflammatory drugs is a promising treatment strategy. Curcumol, a terpenoid natural product, has demonstrated significant anti-inflammatory activity. Herein, we designed and synthesised 42 curcumol derivatives using curcumol as the core scaffold. These derivatives underwent in vitro screening for anti-inflammatory activity, and their structure-activity relationship was assessed. Among them, derivative 2 exhibited potent anti-inflammatory potential, inhibiting the expression of inflammatory markers at the nanomolar level. In addition, its water solubility was considerably improved, thereby laying the foundation for enhanced druggability. Derivative 2 also ameliorated lipopolysaccharide (LPS)-induced ALI and reduced pulmonary inflammation at a dose of 5 mg/kg. Proteomics analysis revealed that the anti-inflammatory effect of this compound primarily involved the mTOR signalling pathway. Furthermore, molecular docking and cellular thermal shift assays indicated that GSK3β is a critical target of action of derivative 2, as verified via western blotting. These findings suggest that derivative 2 can be a lead therapeutic compound for ALI, with GSK3β emerging as a promising novel target for the development of specific anti-ALI drugs.

Metal-free approach for imidazole synthesis via one-pot N-α-C(sp3)-H bond functionalization of benzylamines

A metal-free one-pot method is established for the synthesis of tetrasubstituted imidazoles from the reaction of arylmethylamines and 1,2-dicarbonyls/benzoin. The N-α-C(sp3)-H bond functionalization of arylmethylamines using a catalytic amount of AcOH afforded polysubstituted imidazoles under aerobic conditions in significant yields of up to 95%.

Mechanochemical Cascade Cyclization of Cyclopropyl Ketones with 1,2-Diamino Arenes for the Direct Synthesis of 1,2-Disubstituted Benzimidazoles†

A mechanochemical synthesis of 1,2-disubstituted benzimidazoles from donor-acceptor cyclopropyl ketones and 1,2-diaminoarenes under metal-free and solventless conditions is reported. The reaction does not require inert conditions and is promoted by a stoichiometric amount of 1,1,1,3,3,3-hexafluoroisopropanol. This cascade reaction involves ring-opening, cyclization, and retro-Mannich reaction of cyclopropyl ketones with aryl 1,2-diamines. Compared to its solution-phase counterpart, this mechanochemical approach shows fast reactivity (24 vs 1.5 h). Mechanistic investigations by electrospray ionization mass spectrometry helped us to propose the reaction mechanism.

Synthesis, Characterization, and Cytotoxicity Evaluation of Novel Water-Soluble Cationic Platinum(II) Organometallic Complexes with Phenanthroline and Imidazolic Ligands

Platinum-based chemotherapeutic agents are widely used in the treatment of cancer. However, their effectiveness is limited by severe adverse reactions, drug resistance, and poor water solubility. This study focuses on the synthesis and characterization of new water-soluble cationic monofunctional platinum(II) complexes starting from the [PtCl(η1-C2H4OEt)(phen)] (1, phen=1,10-phenanthroline) precursor, specifically [Pt(NH3)(η1-C2H4OEt)(phen)]Cl (2), [Pt(1-hexyl-1H-imidazole)(η1-C2H4OEt)(phen)]Cl (3), and [Pt(1-hexyl-1H-benzo[d]imidazole)(η1-C2H4OEt)(phen)]Cl (4), which deviate from traditional requirements for antitumor activity. These complexes were evaluated for their cytotoxic effects in comparison to cisplatin, using immortalized cervical adenocarcinoma cells (HeLa), human renal carcinoma cells (Caki-1), and normal human renal cells (HK-2). While complex 2 showed minimal effects on the cell lines, complexes 3 and 4 demonstrated higher cytotoxicity than cisplatin. Notably, complex 4 displayed the highest cytotoxicity in both cancer and normal cell lines. However, complex 3 exhibited the highest selectivity for renal tumor cells (Caki-1) among the tested complexes, compared to healthy cells (HK-2). This resulted in a significantly higher selectivity than that of cisplatin and complex 4. Therefore, complex 3 shows potential as a leading candidate for the development of a new generation of platinum-based anticancer drugs, utilizing biocompatible imidazole ligands while demonstrating promising anticancer properties.

Ferrocenyl Azoles: Versatile N-Containing Heterocycles and their Anticancer Activities

The medicinal chemistry of ferrocene has gained its momentum after the discovery of biological activities of ferrocifen and ferroquine. These ferrocenyl drugs have been designed by replacing the aromatic moiety of the organic drugs, tamoxifen and chloroquine respectively, with a ferrocenyl unit. The promising biological activities of these ferrocenyl drugs have paved a path to explore the medicinal applications of several ferrocenyl conjugates. In these conjugates, the ferrocenyl moiety has played a vital role in enhancing or imparting the anticancer activity to the molecule. The ferrocenyl conjugates induce the cytotoxicity by generating reactive oxygen species and thereby damaging the DNA. In medicinal chemistry, the five membered nitrogen heterocycles (azoles) play a significant role due to their rigid ring structure and hydrogen bonding ability with the biomolecules. Several potent drug candidates with azole groups have been in use as chemotherapeutics. Considering the importance of ferrocenyl moiety and azole groups, several ferrocenyl azole conjugates have been synthesized and screened for their biological activities. Hence, in the view of a wide scope in the development of potent drugs based on ferrocenyl azole conjugates, herein we present the details of synthesis and the anticancer activities of ferrocenyl compounds bearing azole groups such as imidazole, triazoles, thiazole and isoxazoles.

Development of Benzimidazole-Substituted Spirocyclopropyl Oxindole Derivatives as Cytotoxic Agents: Tubulin Polymerization Inhibition and Apoptosis Inducing Studies

A series of spirocyclopropyl oxindoles with benzimidazole substitutions was synthesized and tested for their cytotoxicity against selected human cancer cells. Most of the molecules exhibited significant antiproliferative activity with compound 12 p being the most potent. It exhibited significant cytotoxicity against MCF-7 breast cancer cells (IC50 value 3.14±0.50 μM), evidenced by the decrease in viable cells and increased apoptotic features during phase contrast microscopy, such as AO/EB, DAPI and DCFDA staining studies. Compound 12 p also inhibited cell migration in wound healing assay. Anticancer potential of 12 p was proved by the inhibition of tubulin polymerization with IC50 of 5.64±0.15 μM. These results imply the potential of benzimidazole substituted spirocyclopropyl oxindoles, notably 12 p, as cytotoxic agent for the treatment of breast cancer.

A One-Pot Cascade Strategy toward Organocatalytic Enantioselective Construction of Fused Benzimidazoles

Herein, we describe an asymmetric assembly of ortho-aromatic diamines and formyl tethered Michael acceptors forming chiral fused benzimidazoles. A cinchona-alkaloid-derived bifunctional squaramide catalyst enables the methodology through on-site dihydrobenzimidazole formation followed by an aza-Michael addition/oxidation cascade. This protocol stands out for its excellent catalytic efficiency over the background reaction and its mild conditions, making it more practical. Various Michael acceptors, including enones, ester, and thioester, were successful substrates in this study. Additionally, this methodology has demonstrated scalability and successfully showcased postsynthetic transformations.

Synthesis, Characterization, and Antifungal Activity of Benzimidazole-Grafted Chitosan against Aspergillus flavus

Aspergillus flavus contamination in agriculture and food industries poses threats to human health, leading to a requirement of a safe and effective method to control fungal contamination. Chitosan-based nitrogen-containing derivatives have attracted much attention due to their safety and enhanced antimicrobial applications. Herein, a new benzimidazole-grafted chitosan (BAC) was synthesized by linking the chitosan (CS) with a simple benzimidazole compound, 2-benzimidazolepropionic acid (BA). The characterization of BAC was confirmed by Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance spectroscopy (1H and 13C NMR). Then, the efficiency of BAC against A. flavus ACCC 32656 was investigated in terms of spore germination, mycelial growth, and aflatoxin production. BAC showed a much better antifungal effect than CS and BA. The minimum inhibitory concentration (MIC) value was 1.25 mg/mL for BAC, while the highest solubility of CS (16.0 mg/mL) or BA (4.0 mg/mL) could not completely inhibit the growth of A. flavus. Furthermore, results showed that BAC inhibited spore germination and elongation by affecting ergosterol biosynthesis and the cell membrane integrity, leading to the permeabilization of the plasma membrane and leakage of intracellular content. The production of aflatoxin was also inhibited when treated with BAC. These findings indicate that benzimidazole-derived natural CS has the potential to be used as an ideal antifungal agent for food preservation.

Mutual influence of non-covalent interactions formed by imidazole: A systematic quantum-chemical study

Imidazole is a five-membered heterocycle that is part of a number of biologically important molecules such as the amino acid histidine and the hormone histamine. Imidazole has a unique ability to participate in a variety of non-covalent interactions involving the NH group, the pyridine-like nitrogen atom or the π-system. For many biologically active compounds containing the imidazole moiety, its participation in formation of hydrogen bond NH⋯O/N and following proton transfer is the key step of mechanism of their action. In this work a systematic study of the mutual influence of various paired combinations of non-covalent interactions (e.g., hydrogen bonds and π-interactions) involving the imidazole moiety was performed by means of quantum chemistry (PW6B95-GD3/def2-QZVPD) for a series of model systems constructed based on analysis of available x-ray data. It is shown that for considered complexes formation of additional non-covalent interactions can only enhance the proton-donating ability of imidazole. At the same time, its proton-accepting ability can be both enhanced and weakened, depending on what additional interactions are added to a given system. The mutual influence of non-covalent interactions involving imidazole can be classified as weak geometric and strong energetic cooperativity-a small change in the length of non-covalent interaction formed by imidazole can strongly influence its strength. The latter can be used to develop methods for controlling the rate and selectivity of chemical reactions involving the imidazole fragment in larger systems. It is shown that the strong mutual influence of non-covalent interactions involving imidazole is due to the unique ability of the imidazole ring to effectively redistribute electron density in non-covalently bound systems with its participation.

Photoinduced C-H arylation of 1,3-azoles via copper/photoredox dual catalysis

The visible light-induced C-H arylation of azoles has been accomplished by dual-catalytic system with the aid of an inexpensive ligand-free copper(i)-catalyst in combination with a suitable photoredox catalyst. An organic photoredox catalyst, 10-phenylphenothiazine (PTH), was identified as effective, cost-efficient and environmentally-benign alternative to commonly-used, expensive Ir(iii)-based complexes. The method proved applicable for the C-H arylation of various azole derivatives, including oxazoles, benzoxazoles, thiazoles, benzothiazoles as well as more challenging imidazoles and benzimidazoles. Moreover, the derivatization of complex molecules and the gram scale synthesis of the natural product balsoxin reflected the synthetic utility of the developed strategy. Mechanistic studies were indicative of a single electron transfer-based (SET) mechanism with an aryl radical as key intermediate.

Ruthenium(II)-Catalyzed Sequential C-H/N-H Alkene Annulation Cascade of Phenanthroimidazoles: Synthesis and Photophysical Studies

We report ruthenium(II)-catalyzed sequential C-H/N-H alkenylation cascade of phenanthroimidazole and alkenes to form novel phenanthroimidazoisoindol acrylates via dual C-H activation and aza-Michael reaction. The two nitrogen atoms of the imidazole ring act as directing groups for regioselective dual sequential ortho C-H activation. These polycyclic N-heterocycles were evaluated for their photophysical properties.

Time-series analysis of rhenium(I) organometallic covalent binding to a model protein for drug development

Metal-based complexes with their unique chemical properties, including multiple oxidation states, radio-nuclear capabilities and various coordination geometries yield value as potential pharmaceuticals. Understanding the interactions between metals and biological systems will prove key for site-specific coordination of new metal-based lead compounds. This study merges the concepts of target coordination with fragment-based drug methodologies, supported by varying the anomalous scattering of rhenium along with infrared spectroscopy, and has identified rhenium metal sites bound covalently with two amino acid types within the model protein. A time-based series of lysozyme-rhenium-imidazole (HEWL-Re-Imi) crystals was analysed systematically over a span of 38 weeks. The main rhenium covalent coordination is observed at His15, Asp101 and Asp119. Weak (i.e. noncovalent) interactions are observed at other aspartic, asparagine, proline, tyrosine and tryptophan side chains. Detailed bond distance comparisons, including precision estimates, are reported, utilizing the diffraction precision index supplemented with small-molecule data from the Cambridge Structural Database. Key findings include changes in the protein structure induced at the rhenium metal binding site, not observed in similar metal-free structures. The binding sites are typically found along the solvent-channel-accessible protein surface. The three primary covalent metal binding sites are consistent throughout the time series, whereas binding to neighbouring amino acid residues changes through the time series. Co-crystallization was used, consistently yielding crystals four days after setup. After crystal formation, soaking of the compound into the crystal over 38 weeks is continued and explains these structural adjustments. It is the covalent bond stability at the three sites, their proximity to the solvent channel and the movement of residues to accommodate the metal that are important, and may prove useful for future radiopharmaceutical development including target modification.

Arylazobenzimidazoles: versatile visible-light photoswitches with tuneable Z-isomer stability

Benzimidazole heterocycles are of great importance in medicinal chemistry due to their applicability to a wide range of pharmacological targets, therefore representing a prototypical "privileged structure". In photopharmacology, azoheteroarene photoswitches have emerged as valuable tools for a variety of applications due to the high tuneability of their photophysical properties. Benzimidazole-based photoswitches could therefore enable the optically-controlled investigation of many pharmacological targets and find application in materials science. Here we report a combined experimental and computational investigation of such arylazobenzimidazoles, which allowed us to identify derivatives with near-quantitative bidirectional photoswitching using visible light and highly tuneable Z-isomer stability. We further demonstrate that arylazobenzimidazoles bearing a free benzimidazole N-H group not only exhibit efficient bidirectional photoswitching, but also excellent thermal Z-isomer stability, contrary to previously reported fast-relaxing Z-isomers of N-H azoheteroarenes. Finally, we describe derivatives which can be reversibly isomerized with cyan and red light, thereby enabling significantly "red-shifted" photocontrol over prior azoheteroarenes. The understanding gained in this study should enable future photopharmacological efforts by employing photoswitches based on the privileged benzimidazole structure.

Benzimidazole-Based Derivatives as Apoptotic Antiproliferative Agents: Design, Synthesis, Docking, and Mechanistic Studies

A new class of benzimidazole-based derivatives (4a-j, 5, and 6) with potential dual inhibition of EGFR and BRAFV600E has been developed. The newly synthesized compounds were submitted for testing for antiproliferative activity against the NCI-60 cell line. All newly synthesized compounds 4a-j, 5, and 6 were selected for testing against a panel of sixty cancer cell lines at a single concentration of 10 µM. Some compounds tested demonstrated remarkable antiproliferative activity against the cell lines tested. Compounds 4c, 4e, and 4g were chosen for five-dose testing against 60 human tumor cell lines. Compound 4c demonstrated strong selectivity against the leukemia subpanel, with a selectivity ratio of 5.96 at the GI50 level. The most effective in vitro anti-cancer assay derivatives (4c, 4d, 4e, 4g, and 4h) were tested for EGFR and BRAFV600E inhibition as potential targets for antiproliferative action. The results revealed that compounds 4c and 4e have significant antiproliferative activity as dual EGFR/BRAFV600E inhibitors. Compounds 4c and 4e induced apoptosis by increasing caspase-3, caspase-8, and Bax levels while decreasing the anti-apoptotic Bcl2 protein. Moreover, molecular docking studies confirmed the potential of compounds 4c and 4e to act as dual EGFR/BRAFV600E inhibitors.

Synthesis of 5-(trifluoroacetyl)imidazoles from Bromoenones and Benzimidamides via Aza-Michael Initiated Ring Closure Reaction

INTRODUCTION

A simple method for the preparation of 5-(trifluoroacetyl)imidazoles was elaborated.

METHODS

The reaction of trifluoromethyl(α-bromoalkenyl)ketones with benzimidamides was employed to afford the target heterocycles in good yields.

RESULTS

The assembly of imidazole core proceeds via aza-Michael adduct formation followed by intramolecular nucleophilic substitution and spontaneous aromatization as an oxidation sequence.

CONCLUSION

The yields of target imidazoles can be improved by the use of soft oxidizing agents.

Unlocking the Pharmacological Potential of Benzimidazole Derivatives: A Pathway to Drug Development

Heterocyclic molecules have fascinated a massive interest in medicinal chemistry. They are heterocyclic compounds that have gained significance due to their diverse variety of pharmacological activities. Benzimidazole is a heterocyclic compound consisting of benzene and imidazole rings. The ease of synthesis and the structural versatility of benzimidazole make it a promising scaffold for drug development. Many biological actions of benzimidazole derivatives have been well documented, including antibacterial, antiviral, anticancer, anti-inflammatory, antitubercular, and anthelmintic properties. The mechanism of action of benzimidazole derivatives varies with their chemical structure and target enzyme. This review has explored numerous methods for producing benzimidazole derivatives as well as a broad range of pharmacological activities. SAR investigations are also discussed in this review as they provide crucial details regarding the essential structural qualities that benzimidazole derivatives must have in order to be biologically active, which could aid in the rational design of new drug candidates. Benzimidazole scaffold is an exclusive structure in drug design and discovery. Many new pharmaceutical drugs containing benzimidazole are anticipated to be available within the next ten years as a result of the extensive therapeutic applications of benzimidazole and its derivatives. This review inspired many researchers to develop more biologically active compounds bearing benzimidazole, expanding the scope of finding a remedy for other diseases. From this study, we concluded that 2-substituted benzimidazole was considered more extensively by researchers.

Visible-Light Photoswitchable Benzimidazole Azo-Arenes as β-Arrestin2-Biased Selective Cannabinoid 2 Receptor Agonists

The cannabinoid 2 receptor (CB2 R) has high therapeutic potential for multiple pathogenic processes, such as neuroinflammation. Pathway-selective ligands are needed to overcome the lack of clinical success and to elucidate correlations between pathways and their respective therapeutic effects. Herein, we report the design and synthesis of a photoswitchable scaffold based on the privileged structure of benzimidazole and its application as a functionally selective CB2 R "efficacy-switch". Benzimidazole azo-arenes offer huge potential for the broad extension of photopharmacology to a wide range of optically addressable biological targets. We used this scaffold to develop compound 10 d, a "trans-on" agonist, which serves as a molecular probe to study the β-arrestin2 (βarr2) pathway at CB2 R. βΑrr2 bias was observed in CB2 R internalization and βarr2 recruitment, while no activation occurred when looking at Gα16 or mini-Gαi . Overall, compound 10 d is the first light-dependent functionally selective agonist to investigate the complex mechanisms of CB2 R-βarr2 dependent endocytosis.

TFE-Facilitated Synthesis of Tetrahydropyridino[2,3-d]pyrimidine via Cascade [1,5]-Hydride Transfer/Cyclization

An efficient fluorinated alcohol-driven cascade [1,5]-hydride transfer/cyclization between o-amino pyridyl aldehydes and primary amines has been developed. This unique transformation enabled an array of tetrahydropyridino[2,3-d]pyrimidine construction. Furthermore, the encouraging antifungal activity of Thanatephorus cucumeris was demonstrated by this tetrahydropyridino[2,3-d]pyrimidine core structure.

Discovery of Novel Small Molecule Growth Inhibitors to Manage Pseudomonas Leaf Spot Disease on Peppers (Capsicum sp.)

Pseudomonas leaf spot (PLS) disease in peppers caused by Pseudomonas syringae pv. syringae (Pss) is an emerging seedborne phytopathogen. Pss infection can severely reduce the marketable yield of peppers in favorable environmental conditions and cause significant economic losses. The intensive use of copper-sulfate and streptomycin-sulfate to control PLS and other bacterial diseases is associated with antimicrobial-resistant Pss strains, making these control methods less effective. So, there is an urgent need to develop novel antimicrobials effective against Pss in peppers. Several studies, including those done in our laboratory, have shown that small molecule (SM) antimicrobials are ideal candidates as they can be effective against multidrug resistant bacteria. Therefore, our study aims to identify novel SM growth inhibitors of Pss, assess their safety, and evaluate their efficacy on Pss-infected pepper seeds and seedlings. Using high-throughput screening, we identified 10 SMs (PC1 to PC10) that inhibited the growth of Pss strains at 200 µM or lower concentrations. These SMs were effective against both copper- and streptomycin-resistant as well as biofilm-embedded Pss. These SMs were effective against other plant pathogens (n = 22) at low concentrations (<200 μM) and had no impact on beneficial phytobacteria (n = 12). Furthermore, these SMs showed better or equivalent antimicrobial activity against Pss in infested pepper seeds and inoculated seedlings compared with copper-sulfate (200 μM) and streptomycin (200 μg/ml). Additionally, none of the SMs were toxic to pepper tissues (seeds, seedlings, or fruits), human Caco-2 cells, and pollinator honeybees at 200 μM. Overall, the SMs identified in this study are promising alternative antimicrobials for managing PLS in pepper production.

Design, Synthesis, and Anti-Breast Cancer Potential of Imidazole-Pyridine Hybrid Molecules In Vitro and Ehrlich Ascites Carcinoma Growth Inhibitory Activity Assessment In Vivo

Breast cancer remains a challenging medical issue and is a high priority for biomedical research despite significant advancements in cancer research and therapy. The current study aims to determine the anticancer activity of a group of imidazole-pyridine-based scaffolds against a variety of breast cancer cell lines differing in their receptor expression (estrogen receptor (ER), progesterone receptor (PR), and HER-2). A series of 10 molecules (coded 5a-5j) were synthesized through multicomponent and alkylation reactions. FTIR, MS, 1H, and 13C NMR spectral analyses confirmed the structures and purity of the synthesized molecules. Subsequently, these molecules were tested for their ability to inhibit the viability of cell lines representing carcinoma of the breast, viz., MDA-MB-468 (ER-, PR-, and HER-), BT-474 (ER+, PR+, and HER+), T-47D (ER+, PR+, and HER-), and MCF-7 (ER+, PR+, and HER-) in vitro. Among these 10 molecules, 5a, 5c, 5d, and 5e exhibited better potency, as evidenced by IC50 < 50 μM at 24 h of treatment against BT-474 and MDA-MB-468 cell lines. However, except for 5d, the IC50 value is much higher than 50 μM when tested against T47D and MCF-7 cell lines at 24h. Extended treatment for 48 h reduced the effect of these molecules, as an increase in IC50 was observed. In mice, intraperitoneal administration of 5e retarded the Ehrlich ascites carcinoma (EAC) growth without causing any organ toxicity at the doses tested. In summary, we report the synthesis scheme and key structural requirements for a new series of imidazole-pyridine molecules for in vitro inhibition of the feasibility of breast cancer cells and in vivo inhibition of EAC tumors.

Biomedical applications of selective metal complexes of indole, benzimidazole, benzothiazole and benzoxazole: A review (From 2015 to 2022)

Indole, benzoxazole benzothiazole and benzimidazole are excellent classes of organic heterocyclic compounds. These compounds show significant application in pharmacy, industries, dyes, medicine, polymers and food packages. These compounds also form metal complexes with copper, zinc, cadmium, nickel, cobalt, platinum, gold, palladium chromium, silver, iron, and other metals that have shown to be significant applications. Recently, researchers have attracted enormous attention toward heterocyclic compounds such as indole, benzimidazole, benzothiazole, benzoxazole, and their complexes due to their excellent medicinal applications such as anti-ulcerogenic, anti-cancer, antihypertensive, antifungal, anti-inflammatory, antitubercular, antiparasitic, anti-obesity, antimalarial, antiglycation, antiviral potency, antineuropathic, analgesic antioxidant, antihistaminic, and antibacterial potentials. In this article, we summarize the medicinal applications of these compounds as well as their metal complexes. We hope this article will help researchers in designing and synthesizing novel and potent compounds with significant applications in various fields.

Synthesis and anti-parasites efficacy of coumarin derivatives against Dactylogyrus intermedius

Dactylogyrus is one of the most common parasitic diseases in fish and causes huge losses to the aquaculture industry. With the advantages of safety, low toxicity and easy degradation, plant-derived drugs are ideal for the creation of green aquatic ingredients. The use of plant-derived drugs in aquaculture is limited by their low content and high processing costs, which is a challenge that can be solved by the chemical synthesis of plant-derived drugs. Eleven new coumarin derivatives were synthesized and assessed for their anthelmintic activity in this study. Among them, the derivative 7-((1-tosyl-1H-1,2,3-triazol-4-yl)methoxy)-2H-chromen-2-one (N11) has good anthelmintic activity and its mean anthelmintic efficacy against D. intermedius at a concentration of 10 μM reached 99.84%, which is even better than the anthelmintic activity of the positive control mebendazole. Further studies showed that N11 had concentration values of 3.31 and 1.94 μM for 50% maximal effect (EC50 ) against D. intermedius at 24 and 48 h, respectively. Furthermore, scanning electron microscopy revealed that N11 caused damage to D. intermedius. What is more noteworthy is that a substantial reduction in the ATP content of the parasite was observed following in vitro and in vivo administration of N11. Moreover, it was also found that N11 was able to inhibit the horizontal transmission of D. intermedius. Furthermore, real-time quantitative PCR analysis was utilized to determine the expression profile of genes associated with anti-inflammatory cytokines (IL-10, TGF-β and IL-4) in goldfish. In all examined organs, it was observed that the expression of anti-inflammatory cytokines increased subsequent to treatment with N11, according to the results. Thus, these results all suggest that N11 possesses good anthelmintic activity and is a potentially effective agent for the control of D. intermedius.

Iodine-promoted synthesis of CF3-substituted dihydroimidazobenzimidazole and CF3-dihydroimidazoindole via C-N bond formation

The iodine-promoted cyclization of various N-(2-CF3-2-NHTs)ethylbenzimidazoles and N-(2-CF3-2-NHTs)ethylindoles proceeded smoothly and efficiently under mild basic conditions. This reaction did not require transition metals and afforded the corresponding CF3-dihydroimidazobenzimidazoles and CF3-dihydroimidazoindoles in 85-93% and 42-82% yields, respectively.

Exploration of Remarkably Potential Multitarget-Directed N-Alkylated-2-(substituted phenyl)-1H-benzimidazole Derivatives as Antiproliferative, Antifungal, and Antibacterial Agents

Improving lipophilicity for drugs to penetrate the lipid membrane and decreasing bacterial and fungal coinfections for patients with cancer pose challenges in the drug development process. Here, a series of new N-alkylated-2-(substituted phenyl)-1H-benzimidazole derivatives were synthesized and characterized by 1H and 13C NMR, FTIR, and HRMS spectrum analyses to address these difficulties. All the compounds were evaluated for their antiproliferative, antibacterial, and antifungal activities. Results indicated that compound 2g exhibited the best antiproliferative activity against the MDA-MB-231 cell line and also displayed significant inhibition at minimal inhibitory concentration (MIC) values of 8, 4, and 4 μg mL-1 against Streptococcus faecalis, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus compared with amikacin. The antifungal data of compounds 1b, 1c, 2e, and 2g revealed their moderate activities toward Candida albicans and Aspergillus niger, with MIC values of 64 μg mL-1 for both strains. Finally, the molecular docking study found that 2g interacted with crucial amino acids in the binding site of complex dihydrofolate reductase with nicotinamide adenine dinucleotide phosphate.

The combination of multi-approach studies to explore the potential therapeutic mechanisms of imidazole derivatives as an MCF-7 inhibitor in therapeutic strategies

Breast cancer covers a large area of research because of its prevalence and high frequency all over the world. This study is based on drug discovery against breast cancer from a series of imidazole derivatives. A 3D-QSAR and activity atlas model was developed by exploring the dataset computationally, using the machine learning process of Flare. The dataset of compounds was divided into active and inactive compounds according to their biological and structural similarity with the reference drug. The obtained PLS regression model provided an acceptable r ² = 0.81 and q² = 0.51. Protein-ligand interactions of active molecules were shown by molecular docking against six potential targets, namely, TTK, HER2, GR, NUDT5, MTHFS, and NQO2. Then, toxicity risk parameters were evaluated for hit compounds. Finally, after all these screening processes, compound C10 was recognized as the best-hit compound. This study identified a new inhibitor C10 against cancer and provided evidence-based knowledge to discover more analogs.

Synthesis and anticancer activity of podophyllotoxin derivatives with nitrogen-containing heterocycles

Three series of podophyllotoxin derivatives with various nitrogen-containing heterocycles were designed and synthesized. The antitumor activity of these podophyllotoxin derivatives was evaluated in vitro against a panel of human tumor cell lines. The results showed that podophyllotoxin-imidazolium salts and podophyllotoxin-1,2,4-triazolium salts a1-a20 exhibited excellent cytotoxic activity. Among them, a6 was the most potent cytotoxic compound with IC₅₀ values of 0.04-0.29 μM. Podophyllotoxin-1,2,3-triazole derivatives b1-b5 displayed medium cytotoxic activity, and podophyllotoxin-amine compounds c1-c3 has good cytotoxic activity with IC₅₀ value of 0.04-0.58 μM. Furthermore, cell cycle and apoptosis experiments of compound a6 were carried out and the results exhibited that a6 could induce G2/M cell cycle arrest and apoptosis in HCT-116 cells.

Dual Photochemistry of Benzimidazole

Monomers of benzimidazole trapped in an argon matrix at 15 K were characterized by vibrational spectroscopy and identified as 1H-tautomers exclusively. The photochemistry of matrix-isolated 1H-benzimidazole was induced by excitations with a frequency-tunable narrowband UV light and followed spectroscopically. Hitherto unobserved photoproducts were identified as 4H- and 6H-tautomers. Simultaneously, a family of photoproducts bearing the isocyano moiety was identified. Thereby, the photochemistry of benzimidazole was hypothesized to follow two reaction pathways: the fixed-ring and the ring-opening isomerizations. The former reaction channel results in the cleavage of the NH bond and formation of a benzimidazolyl radical and an H-atom. The latter reaction channel involves the cleavage of the five-membered ring and concomitant shift of the H-atom from the CH bond of the imidazole moiety to the neighboring NH group, leading to 2-isocyanoaniline and subsequently to the isocyanoanilinyl radical. The mechanistic analysis of the observed photochemistry suggests that detached H-atoms, in both cases, recombine with the benzimidazolyl or isocyanoanilinyl radicals, predominantly at the positions with the largest spin density (revealed using the natural bond analysis computations). The photochemistry of benzimidazole therefore occupies an intermediate position between the earlier studied prototype cases of indole and benzoxazole, which exhibit exclusively the fixed-ring and the ring-opening photochemistries, respectively.

Benzimidazole and its derivatives as cancer therapeutics: The potential role from traditional to precision medicine

Cancer is the second leading cause of mortality globally which remains a continuing threat to human health today. Drug insensitivity and resistance are critical hurdles in cancer treatment; therefore, the development of new entities targeting malignant cells is considered a high priority. Targeted therapy is the cornerstone of precision medicine. The synthesis of benzimidazole has garnered the attention of medicinal chemists and biologists due to its remarkable medicinal and pharmacological properties. Benzimidazole has a heterocyclic pharmacophore, which is an essential scaffold in drug and pharmaceutical development. Multiple studies have demonstrated the bioactivities of benzimidazole and its derivatives as potential anticancer therapeutics, either through targeting specific molecules or non-gene-specific strategies. This review provides an update on the mechanism of actions of various benzimidazole derivatives and the structure‒activity relationship from conventional anticancer to precision healthcare and from bench to clinics.

Silica supported lanthanum trifluoroacetate and trichloroacetate as an efficient and reusable water compatible Lewis acid catalyst for synthesis of 2,4,5-triarylimidazoles via a solvent-free green approach

In the present research article, we have developed solid heterogenous silica supported lanthanum trifluoroacetate and trichloroacetate as green Lewis acid catalysts. These catalysts were synthesized by a novel, simple, cheap, clean, and environment friendly method. The physicochemical properties of the prepared catalysts were well studied and characterized by sophisticated spectroscopic techniques such as FTIR, TGA, XRD, EDX, SEM, TEM and BET analysis. The catalyst was utilized in the synthesis of arylimidazole derivatives via green protocols under solvent-free conditions at 70 °C with a higher yield, mild reaction conditions and a short reaction time. The catalyst works superiorly in water as well as in various organic solvents as a reusable and easily recoverable catalyst.

N-substitution Reactions of 2-Aminobenzimidazoles to Access Pharmacophores

Benzimidazole (BI) and its derivatives are interesting molecules in medicinal chemistry because several of these compounds have a diversity of biological activities and some of them are even used in clinical applications. In view of the importance of these compounds, synthetic chemists are still interested in finding new procedures for the synthesis of these classes of compounds. Astemizole (antihistaminic), Omeprazole (antiulcerative), and Rabendazole (fungicide) are important examples of compounds used in medicinal chemistry containing BI nuclei. It is interesting to observe that several of these compounds contain 2-aminobenzimidazole (2ABI) as the base nucleus. The structures of 2ABI derivatives are interesting because they have a planar delocalized structure with a cyclic guanidine group, which have three nitrogen atoms with free lone pairs and labile hydrogen atoms. The 10-π electron system of the aromatic BI ring conjugated with the nitrogen lone pair of the hexocyclic amino group, making these heterocycles to have an amphoteric character. Synthetic chemists have used 2ABI as a building block to produce BI derivatives as medicinally important molecules. In view of the importance of the BIs, and because no review was found in the literature about this topic, we reviewed and summarized the procedures related to the recent methodologies used in the N-substitution reactions of 2ABIs by using aliphatic and aromatic halogenides, dihalogenides, acid chlorides, alkylsulfonic chlorides, carboxylic acids, esters, ethyl chloroformates, anhydrides, SMe-isothioureas, alcohols, alkyl cyanates, thiocyanates, carbon disulfide and aldehydes or ketones to form Schiff bases. The use of diazotized 2ABI as intermediate to obtain 2-diazoBIs was included to produce Nsubstituted 2ABIs of pharmacological interest. Some commentaries about their biological activity were included.

Small Molecules Containing Amphoteric Imidazole Motifs as Sensitizers for Dye-Sensitized Solar Cells: An Overview

Organic dyes, porphyrins and inorganic complexes containing imidazole (IM) motifs have been demonstrated as a new class of sensitizers in dye-sensitized solar cells (DSSCs). Particularly, the amphoteric nature of IM-based motifs allows them to be used as donors (D), auxiliary donors (D_A), linker/branch (π), or acceptors (A) in D-π-A-based organic dyes and porphyrins and also employed as cyclometalated heteroleptic and ancillary ligands in the Ru(II) and Ir(III) complexes for DSSCs. It is noteworthy that the introduction of IM chromophores in the dyes of D-π-A configuration can improve the light-harvesting properties and prohibit the charge recombination reactions due to the extension of the π-conjugated structures and hydrophobic nature. Similarly, in the case of inorganic complexes, the presence of IM motifs as ligands can improve the light-harvesting ability, give facilely tuned HOMO and LUMO energy levels, increase the charge recombination resistance and photostability. This results in enhanced photocurrent (J_SC) and photovoltage (V_OC) and consequently solar-to-power conversion efficiency (η) of DSSC devices based on Ru(II) and Ir(III) complexes. Considering the interesting DSSC applications of IM-derived molecules, in this review, we therefore comprehensively discuss their photophysical, electrochemical and photovoltaic properties reported so far and establish their structure-activity relationship to further advance the η of DSSCs. To the best of our knowledge, there is no such a review interpreting the importance of molecules possessing IM-motifs for DSSC applications to date.

Novel Imidazole Liquid Crystals; Experimental and Computational Approaches

The liquid crystalline materials named (E)-4-(2-(4-oxo-5,5-diphenyl-4,5-dihydro-1H-imidazol-2-yl)hydrazineylidene)methyl)phenyl and 4-(alkoxy)benzoate, In, were synthesized and their mesomorphic behaviors were examined. The chemical structures of the produced compounds were confirmed by Fourier-transform infrared spectroscopy (FT-IR), NMR, and elemental analysis. Differential scanning calorimetry (DSC) and polarized optical microscopy were used to investigate the mesomorphic properties of designed heterocyclic derivatives. All the compounds tested had suitable thermal stability and enantiotropic behavior of smectogenic temperature ranges. Furthermore, the enantiotropic smectic C phases were observed to cover all the homologues. Moreover, computational investigations corroborated the experimental findings of the mesomorphic behavior. The reactivity parameters were computed for the derivatives and linked with the experimental data. Theoretical calculations revealed that the polarizability of the studied series increases with the chain length, whereas the HOMO–LUMO energy gap or other reactivity descriptors were less sensitive to the size of the system. On the other hand, the predicted thermodynamic parameters revealed the size dependence of thermal stability of the compounds.

Multicomponent Assembly of Trisubstituted Imidazoles and Their Photochemical Cyclization into Fused Polyheterocyclic Scaffolds

A straightforward route to a large and diverse library of trisubstituted imidazoles was established via a three-component reaction of 2-oxoaldehydes, 1,3-dicarbonyl compounds, and acyclic nitrogen bis-nucleophiles. The obtained products were subsequently explored in a photochemical cyclization yielding a variety of imidazole-fused polycyclic compounds.

Design, Synthesis and Cytotoxicity Evalufation of Substituted Benzimidazole Conjugated 1,3,4-Oxadiazoles

Two series of 2-substituted benzimidazole conjugated 1,3,4-oxadiazole derivatives were designed, synthesized and evaluated for their cytotoxic activities against the three human cancer cell lines (cervical cancer (HeLa), breast cancer (MCF-7) and lung cancer (A549)). As the results 14 compounds demonstrated consistent to stronger cytotoxicities compared to the control 5-fluorouracil (5-FU) towards the tested cell lines including 4c (HeLa); 4b, 4e, 4h, 7i-j, 7m-n, 7s (MCF-7); 7b (MCF-7, A549); 7h (HeLa, MCF-7); and 4d, 4i, 7c (HeLa, MCF-7, A549), with the IC₅₀ ranging from 2.7 to 38 µM. Notably, compound 4b illustrated almost 5-fold activity against the MCF-7 while 4d, 4i were 9- and 8-fold (HeLa), 4.5- and 13-fold (MCF-7), 4.7- and 4-fold (A549) increase in activity compared to 5-FU, respectively, and were found as lead compounds. These findings suggest that compounds 4b, 4d and 4i merit further characterization and can serve as promising scaffolds in the discovery of new potent anticancer agents.

Novel benzimidazole derivatives; synthesis, bioactivity and molecular docking study as potent urease inhibitors

BACKGROUND

Benzimidazole derivatives are widely used to design and synthesize novel bioactive compounds. There are several approved benzimidazole-based drugs on the market.

OBJECTIVES

In this study, we aimed to design and synthesize a series of novel benzimidazole derivatives 8a-n that are urease inhibitors.

METHODS

All 8a-n were synthesized in a multistep. To determine the urease inhibitory effect of 8a-n, the urease inhibition kit was used. The cytotoxicity assay of 8a-n was determined using MTT method. Molecular modelling was determined using autodock software.

RESULTS

All 8a-n were synthesized in high yield, and their structures were determined using 1H-NMR, 13C-NMR, MS, and elemental analyses. In compared to thiourea and hydroxyurea as standards (IC50: 22 and 100 µM, respectively), all 8a-n had stronger urease inhibition activity (IC50: 3.36-10.81 µM). With an IC50 value of 3.36 µM, 8e had the best enzyme inhibitory activity. On two evaluated cell lines, the MTT cytotoxicity experiment revealed that all 8a-n have IC50 values greater than 50 µM. Finally, a docking investigation revealed a plausible way of interaction between the 8e and 8d and the enzyme's active site's key residues.

CONCLUSION

The synthesized benzimidazole derivatives exhibit high activity, suggesting that further research on this family of compounds would be beneficial to finding a potent urease inhibitor.

Quorum Sensing and Biofilm Disrupting Potential of Imidazole Derivatives in Chromobacterium violaceum Using Antimicrobial and Drug Discovery Approaches

Population of drug-resistant bacteria have increased at an alarming rate in the past few decades. The major reason for increasing drug resistance is the lack of new antibiotics and limited drug targets. It has therefore been a vital task to develop new antibiotics with different drug targets. Two such targets are biofilm formation and quorum sensing. Quorum sensing is cell to cell communication used by bacteria that initiates many important survival processes and aids in establishing pathogenesis. Both biofilm and quorum sensing are inter-related processes and play a major role in physiological and pathogenesis processes. In this study, five novel imidazole derivatives (IMA-1-IMA-5) were synthesised and tested for their antibacterial and anti-quorum sensing activities against Chromobacterium violaceum using different in silico and in vitro techniques following the standard protocols. In silico results revealed that all compounds were able to effectively bind to and interact sufficiently with the target protein CviR. CviR is a protein to which autoinducers bind to initiate the quorum sensing process. In silico results also revealed that the compounds generated favourable structural dynamics implying that the compounds would be able to effectively bind to CviR and inhibit quorum sensing. Susceptibility results revealed that IMA-1 is the most active of all the derivatives against both planktonic cells and biofilms. Qualitative and quantitative evaluation of anti-quorum sensing activity at sub-inhibitory concentrations of these compounds also revealed high activity for IMA-1. Down-regulation of most of the quorum sensing genes when cells were treated with the test compounds affirmed the high anti-quorum sensing activities of these compounds. The results from this study are promising and urges on the use of anti-quorum sensing and biofilm disrupting molecules to combat multi-drug resistance problem.