Synthesis of novel 1,2,5-trisubstituted benzimidazoles as potential antitumor agents

Evaluation of the Antifungal Properties of Azomethine-Pyrazole Derivatives from a Structural Perspective

About 95 % of candidiasis infections worldwide are attributed to five Candida fungi species, with C. albicans being the most prevalent and severe. Due to resistance phenomena, the last decade has seen a significant challenge for candidiasis treatment with antifungal drugs, which has led to an urgent need for new antifungal agents. In this article, we report the synthesis of a series of azomethine-pyrazole derivatives bearing a para-substituted azo-phenyl ring. These compounds were evaluated as antifungal agents against Candida species and Cryptococcus neoformans strains. Compound ClAzoNH, substituted by chloride, displayed the highest toxicity on Candida albicans, with an MIC50 value of 2.08 μg/mL, while methoxy-substituted MeOAzoNH showed moderate inhibitory activity. The unsubstituted AzoNH compound exhibited the highest activity towards Candida tropicalis, Candida glabrata, Candida parapsilosis, and Candida krusei strains. In the case of C. albicans, the CaCYP51 protein appears to be the most probable biological target, while for C. neoformans, interactions with the CnFTase protein explained the in vitro results.

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.

Therapeutic Potential of Benzimidazoisoquinoline Derivatives in Alleviating Murine Hepatic Fibrosis

Short Title: Benzimidazoisoquinoline derivatives as potent antifibrotics Hepatic fibrosis is a pathological condition of liver disease with an increasing number of cases worldwide. Therapeutic strategies are warranted to target the activated hepatic stellate cells (HSCs), the collagen-producing cells, an effective strategy for controlling the disease progression. Benzimidazoisoquinoline derivatives were synthesized as hybrid molecules by the combination of benzimidazoles and isoquinolines to evaluate their anti-fibrotic potential using an in-vitro and in-vivo model of hepatic fibrosis. A small library of benzimidazoisoquinoline derivatives (1-17 and 18-21) was synthesized from 2-aryl benzimidazole and acetylene functionalities through C-H and N-H activation. Compounds (10 and its recently synthesized derivatives 18-21) depicted a significant decrease in PDGF-BB and/or TGFβ-induced proliferation (1.7-1.9 -fold), migration (3.5-5.0 -fold), and fibrosis-related gene expressions in HSCs. These compounds could revert the hepatic damage caused by chronic exposure to hepatotoxicants, ethanol, and/or carbon tetrachloride as evident from the histological, biochemical, and molecular analysis. Anti-fibrotic effect of the compounds was supported by the decrease in the malondialdehyde level, collagen deposition, and gene expression levels of fibrosis-related markers such as α-SMA, COL1α1, PDGFRβ, and TGFRIIβ in the preclinical models of hepatic fibrosis. In conclusion, the synthesized benzimidazoisoquinoline derivatives (compounds 18, 19, 20, and 21) possess anti-fibrotic therapeutic potential against liver fibrosis.

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.

2,4-Diaryl-pyrimido[1,2-a]benzimidazole derivatives as novel anticancer agents endowed with potent anti-leukemia activity: Synthesis, biological evaluation and kinase profiling

Acute myeloid leukemia (AML) stands as one of the most aggressive type of human cancer that can develop rapidly and thus requires immediate management. In the current study, the development of novel derivatives of pyrimido[1,2-a]benzimidazole (5a-p) as potential anti-AML agents is reported. The prepared compounds 5a-p were inspected for their in vitro anti-tumor activity at NCI-DTP and subsequently 5h was selected for full panel five-dose screening to assess its TGI, LC₅₀ and GI₅₀ values. Compound 5h showed effective anti-tumor activity at low micromolar concentration on all tested human cancer cell lines with GI₅₀ range from 0.35 to 9.43 μM with superior sub-micromolar activity towards leukemia. Furthermore, pyrimido[1,2-a]benzimidazoles 5e-l were tested on a panel ofhuman acute leukemia cell lines, namely HL60, MOLM-13, MV4-11, CCRF-CEM and THP-1, where 5e-h reached single-digit micromolar GI₅₀ values for all the tested cell lines. All prepared compounds were first tested for inhibitory action against the leukemia-associated mutant FLT3-ITD, as well as against ABL, CDK2, and GSK3 kinases, in order to identify the kinase target for the herein described pyrimido[1,2-a]benzimidazoles. However, the examined molecules disclosed non-significant activity against these kinases. Thereafter, a kinase profiling on a panel of 338 human kinases was then used to discover the potential target. Interestingly, pyrimido[1,2-a]benzimidazoles 5e and 5h significantly inhibited BMX kinase. Further investigation for the effect on cell cycle of HL60 and MV4-11 cells and caspase 3/7 activity was also performed. In addition, the changes in selected proteins (PARP-1, Mcl-1, pH3-Ser10) associated with cell death and viability were analyzed in HL60 and MV4-11 cells by immunoblotting.

DNA-binding, cleavage, antibacterial and in vitro anticancer activity of copper(II) mixed ligand complexes of 2-(((6-chloro-1H-benzo[d]imidazol-2-yl)methyl)amino)aceticacid and polypyridyl ligands

A tridentate ligand(A), 2-(((6-chloro-1H-benzo[d]imidazol-2-yl)methyl)amino) aceticacid (Cl-BIGH) was synthesised by the Phillips condensation of 4-chlorobenzene-1,2-diamine and iminodiaceticacid in 1:2 molar ratio. Its Cu(II) mixed ligand complexes[Cu(II)-A-L] were obtained by involving other co-ligands(L): 2,2΄-bipyridine(L₁), 4,4΄-dimethyl-2,2΄-bipyridyl(L₂), 5,5΄-dimethyl-2,2΄-bipyridyl(L₃) and 1,10 phenanthroline(L₄). The complexes were characterized by elemental analysis, thermal analysis, molar conductance, magnetic moment measurements, X-ray diffraction, FTIR, UV-Visible, ESR spectroscopy, mass spectrometry and cyclic voltammetry. From the spectral and analytical data, the ternary complexes [Cu(Cl-BIGH)(L_1-4)]ClO₄ were found to form in 1:1:1(Cu(II): Cl-BIGH: L) molar ratio. The geometry of the mixed-ligand complexes were found to be 5-coordinated square pyramidal or trigonal bipyramidal with polycrystalline natures. The DNA binding and cleaving abilities, antibacterial and the in vitro cytotoxicity of the complexes were explored. The molecular docking was used to predict the efficiency of binding of the metal complexes with COX- 2.Communicated by Ramaswamy H. Sarma.

Systems pharmacology aiding benzimidazole scaffold as potential lead compounds against leishmaniasis for functional therapeutics

Systems pharmacology helps to understand the complex relationships between biological systems, drugs, and infection model; Leishmania major being one of them. It has aided the drug discovery process by addressing the concerns about economic stress, drug toxicity, and the emergence of resistance. Two million new leishmaniasis cases are reported annually, and >350 million people are at risk globally due to the parasite Leishmania. Trypanothione reductase (TryR) from the parasite-specific redox metabolism is a promising target. In the discipline of medicinal chemistry, benzimidazole is a strong pharmacophore and exhibits a broad range of biological activities. In the current study, benzimidazole derivatives were explored using computational, enzyme kinetics, biological activity, cytotoxic impact characterization, and in-silico ADME-Tox predictions, followed by their confirmation through in-vitro and animal experiments to discover novel inhibitors for TryR from Leishmania major. During rigorous in-silico screening, two benzimidazole derivatives were chosen for further experimentation. In-vitro testing revealed that compound C1 has a higher binding affinity for the TryR protein. Treatment with compound C1 caused significant morphological changes in the parasite, including size reduction, membrane blebbing, loss of motility, and improved anti-leishmanial efficacy. The compound C1 had significant anti-leishmanial potential against L. major promastigotes and demonstrated apoptosis-mediated leishmanicidal activity (apoptosis-like cell death). Furthermore, BALB/c female mice treated with C1 reduced parasite burden. Our findings depicts that C1 successfully lowered the parasite load and has a therapeutic impact on infected mice making C1 as a promising lead compound that, with additional modifications, may be exploited to create novel anti-leishmanial therapies.

New Pyrazolo-Benzimidazole Mannich Bases with Antimicrobial and Antibiofilm Activities

A new series of pyrazolo-benzimidazole hybrid Mannich bases were synthesized, characterized by ¹H-NMR, ¹³C-NMR, IR, UV-Vis, MS, and elemental analysis. In vitro cytotoxicity of the new compounds studied on fibroblast cells showed that the newly synthesized pyrazolo-benzimidazole hybrid derivatives were noncytotoxic until the concentration of 1 μM and two compounds presented a high degree of biocompatibility. The antibacterial and antibiofilm activity of the newly synthesized compounds was assayed on Gram-positive Staphylococcus aureus ATCC25923, Enterococcus faecalis ATCC29212, and Gram-negative Pseudomonas aeruginosa ATCC27853, Escherichia coli ATCC25922 strains. All synthesized compounds 5a–g are more active against all three tested bacterial strains Staphylococcus aureus ATCC25923, Enterococcus faecalis ATCC29212, and Escherichia coli ATCC25922 than reference drugs (Metronidazole, Nitrofurantoin), with the exception of compounds 5d and 5g, which are less active compared to Nitrofurantoin, and all synthesized compounds 5a–g are more active against Pseudomonas aeruginosa ATCC27853 compared to reference drugs (Metronidazole, Nitrofurantoin). Compound 5f showed the best activity against Staphylococcus aureus ATCC 25923, with a MIC of 150 μg/mL and has also inhibited the biofilm formed by all the bacterial strains, having an MBIC of 310 µg/mL compared to the reference drugs (Metronidazole, Nitrofurantoin).

Benzimidazoles Against Certain Breast Cancer Drug Targets: A Review

BACKGROUND

Benzimidazoles are widely used scaffolds against various types of cancer including breast cancer. To this end, anticancer agents must be developed using the knowledge of the specific targets of BC.

OBJECTIVE

In this study, we aim to review the compounds used against some of the biomolecular targets of breast cancer. To this end, we present information about the various targets, with their latest innovative studies.

CONCLUSION

Benzimidazole ring is an important building block that can target diverse cancer scenarios since it can structurally mimic biomolecules in the human body. Additionally, many studies imply the involvement of this moiety on a plethora of pathways and enzymes related to BC. Herein, our target-based collection of benzimidazole derivatives strongly suggests the utilization of benzimidazole derivatives against BC.

Density functional theory calculations and molecular docking of 2-phenylbenzimidazoles with estrogen receptor for quantitative structure-activity relationship studies

Benzimidazole derivatives, especially 2-phenylbenzimidazole with various substituents on the C-5, C-2 and C-6 positions, are so important in pharmaceutical chemistry. Multiple linear regression was applied to predict the activity of 27 novel 2-phenylbenzimidazole derivatives as anticancer agents. At first, we made an effort to create a QSAR model for a selected series of novel 2-phenylbenzimidazole with density functional theory and molecular docking descriptors. Then, we tried to investigate the nature of the interactions between 2-phenylbenzimidazole derivatives and the estrogen receptor using the molecular docking method. Six descriptors of MATS4e, GATS5e, R6v, R1v+, dipole moment, and torsional free energy were selected for modelling. Due to docking results, increase in the binding energy, and decrease in the dipole moment could increase inhibitor activity.

Synthesis of biologically active heterocyclic compounds from allenic and acetylenic nitriles and related compounds

Cyclic and polycyclic compounds containing moieties such as imidazole, pyrazole, isoxazole, thiazoline, oxazine, indole, benzothiazole and benzoxazole benzimidazole are prized molecules because of the various pharmaceutical properties that they display. This led Prof. Landor and co-workers to engage in the synthesis of several of them such as alkylimidazolenes, oxazolines, thiazolines, pyrimidopyrimidines, pyridylpyrazoles, benzoxazines, quinolines, pyrimidobenzimidazoles and pyrimidobenzothiazolones. This review covers the synthesis of biologically active heterocyclic compounds by the Michael addition and the double Michael addition of various amines and diamines on allenic nitriles, acetylenic nitriles, hydroxyacetylenic nitriles, acetylenic acids and acetylenic aldehydes. The heterocycles were obtained in one step reaction and in most cases, did not give side products. A brief discussion on the biological activities of some heterocycles is also provided.

Synthesis, anticancer evaluation and molecular docking studies of new benzimidazole- 1,3,4-oxadiazole derivatives as human topoisomerase types I poison

In this study, some benzimidazole-oxadiazole derivatives were synthesised and tested for their in vitro anticancer activities on five cancer cell lines, including HeLa, MCF7, A549, HepG2 and C6. Their structures were elucidated by IR, ¹H-NMR, ¹³C-NMR, 2 D-NMR and HRMS spectroscopic methods. Among all screened compounds; 5a, 5b, 5d, 5e, 5k, 5l, 5n and 5o exhibited potent selective cytotoxic activities against various tested cancer cell lines. Especially, compounds 5l and 5n exhibited the most antiproliferative activity than Hoechst 33342 and doxorubicin against HeLa cell line, with IC₅₀ of 0.224 ± 0.011 µM and 0.205 ± 0.010 µM, respectively. Furthermore, these potent lead cytotoxic agents were evaluated in terms of their inhibition potency against Topoisomerase I and it was determined that selected compounds inhibited the Topoisomerase I. Docking studies were performed and probable interactions in the DNA-Topo I enzyme complex was determined.

Synthesis, state-of-the-art NMR-binding and molecular modeling study of new benzimidazole core derivatives as Pin1 inhibitors: Targeting breast cancer

New series of benzimidazole ring core conjugated with either dithiocarbamate or thiopropyl linkers, hybridized with different secondary amines were synthesized; 5-15 and 22-31; respectively. The new compounds were characterized by different spectroscopic techniques (¹H, ¹³C 1D & 2D NMR, ESI-MS and IR). They were screened for in vitro anticancer activity against breast cancer using MCF7 cell line. The results obtained revealed that compounds 5, 12, 15 and 25 were the most active among the synthesized series exhibiting IC₅₀ < 10 µg/ml against DOX. To characterize targeting breast cancer on molecular level, binding to ¹⁵N-labeled Pin1 enzyme was conducted using state-of-the-art 2D NMR binding experiments. Results showed promising binding between compounds 5, 12, and 25 by chemical shift perturbation (peak shifting or peak disappearance). Molecular docking study were quite valuable to explain the binding mode of active derivatives via hydrogen bonding. Additional contact preferences and surface mapping studies stated the similarity pattern between active candidates which may pave the way for more precise anti breast cancer target optimization.

In-silico molecular design of heterocyclic benzimidazole scaffolds as prospective anticancer agents

Benzimidazole is a valuable pharmacophore in the field of medicinal chemistry and exhibit wide spectrum of biological activity. Molecular docking technique is routinely used in modern drug discovery for understanding the drug-receptor interaction. The selected data set of synthesized benzimidazole compounds was evaluated for its in vitro anticancer activity against cancer cell lines (HCT116 and MCF7) by sulforhodamine B (SRB) assay. Further, molecular docking study of data set was carried out by Schrodinger-Maestro v11.5 using CDK-8 (PDB code: 5FGK) and ER-alpha (PDB code: 3ERT) as possible target for anticancer activity. Molecular docking results demonstrated that compounds 12, 16, N9, W20 and Z24 displayed good docking score with better interaction within crucial amino acids and corelate to their anticancer results. ADME results indicated that compounds 16, N9 and W20 have significant results within the close agreement of the Lipinski's rule of five and Qikprop rule within the range and these compounds may be taken as lead molecules for the discovery of new anticancer agents.

Benzimidazole scaffolds as promising antiproliferative agents: a review

Cancer is one of the most serious medical problem and second leading cause of death in the world, characterized by a deregulation of the cell cycle which mainly results in a progressive loss of cellular differentiation and uncontrolled cellular growth. The benzimidazole is a heterocyclic moiety found in extensive number of natural and biological active molecules. Benzimidazole derivatives might be considered as auxiliary isosters of nucleotides having attached heterocyclic cores in their structures, cooperate effortlessly with biopolymers and have potential action for chemotherapeutic applications. Benzimidazole and its derivatives displayed a wide range of biological activity because of its structural similarity with the naturally occurring nucleotides. Benzimidazole has established huge alertness in current time and is extremely significant heterocyclic pharmacophore in recent drug innovation and medicinal chemistry. The present review summarizes the chemistry of various substituted benzimidazole derivatives with their antiproliferative significance towards the various cancer cell lines such as HCT116, MCF7, HeLa, HepG2, A549 and A431.

Design of new quinolin-2-one-pyrimidine hybrids as sphingosine kinases inhibitors

Sphingosine-1-phosphate is now emerging as an important player in cancer, inflammation, autoimmune, neurological and cardiovascular disorders. Abundance evidence in animal and humans cancer models has shown that SphK1 is linked to cancer. Thus, there is a great interest in the development new SphK1 inhibitors as a potential new treatment for cancer. In a search for new SphK1 inhibitors we selected the well-known SKI-II inhibitor as the starting structure and we synthesized a new inhibitor structurally related to SKI-II with a significant but moderate inhibitory effect. In a second approach, based on our molecular modeling results, we designed new structures based on the structure of PF-543, the most potent known SphK1 inhibitor. Using this approach, we report the design, synthesis and biological evaluation of a new series of compounds with inhibitory activity against both SphK1 and SphK2. These new inhibitors were obtained incorporating new connecting chains between their polar heads and hydrophobic tails. On the other hand, the combined techniques of molecular dynamics simulations and QTAIM calculations provided complete and detailed information about the molecular interactions that stabilize the different complexes of these new inhibitors with the active sites of the SphK1. This information will be useful in the design of new SphK inhibitors.

Benzimidazole Schiff base derivatives: synthesis, characterization and antimicrobial activity

A series of Schiff bases (3.a–f) bearing benzimidazole moiety was successfully synthesized in ethanol by refluxing Oct-2-ynoic acid (1,3-dihydrobenzimidazole-2-ylidene)amide with substituted amines. Fourier transform infrared (FTIR), ultra violet light (UV–VIS), elemental analysis, proton (¹H) and carbon (¹³C) nuclear magnetic resonance spectroscopy were used to characterize the newly synthesized Schiff bases. Micro dilution method was used to determine the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of the Schiff bases, against 14 human pathogenic bacteria (8 Gram negative and 6 Gram positive) and against 7 fungal strains (5 Aspergillus and 2 Fusarium) representatives. Antimalarial activity against Plasmodium falciparum and antitrypanosomal property against Trypanosoma brucei was studied in vitro at a single dose concentration of the Schiff bases. Cytotoxicity of the Schiff bases was assessed against human cervix adenocarcinoma (HeLa) cells. Results obtained show that the newly synthesized Schiff bases are very potent antimicrobial agents. Gram negative bacteria Klebsiella pneumonia and Escherichia coli were more affected on exposure to Compounds 3.c–f (MIC 7.8 µg/mL) which in turn exhibited more antibacterial potency than nalidixic acid reference drug that displayed MICs between 64 and 512 µg/mL against K. pneumonia and E. coli respectively. The test compounds also demonstrated high cytotoxic effect against Aspergillus flavus and Aspergillus carbonarius as they displayed MFC 7.8 and 15.6 µg/mL. Compound 3.c exhibited the highest fungicidal property from this series with MFC alternating between 7.8 and 15.6 µg/mL against the investigated strains. The malarial activity revealed Compounds 3.c and 3.d as the more potent antiplasmodial compounds in this group exhibiting 95% and 85% growth inhibition respectively. The IC₅₀ of Compounds 3.c and 3.d were determined and found to be IC₅₀ 26.96 and 28.31 µg/mL respectively. Compound 3.a was the most cytotoxic agent against HeLa cells in this group with 48% cell growth inhibition. Compounds 3.c, 3.d and 3.f were biocompatible with HeLa cells and displayed low toxicity. With a very low cytotoxic effect against HeLa, compound 3.c stands out to be a very good antiparasitic agent and consideration to further evaluate the candidate drug against others cell lines is necessary.

Synthesis, Antioxidant and Antiurease Activities of Some New 5,6- dichloro-2-(4-fluorobenzyl)-1H-benzimidazole Derivatives Containing Furan, Oxadiazole, Triazole and Thiadiazole Moieties

Background:

Benzimidazoles and its derivatives have been attracting interest for many years because of their biological activities. Benzimidazoles containing different heterocyclic moieties have wide range of biological activities such as antimicrobial, antioxidant, anticancer, antiviral, etc.

Methods:

In this study, some benzimidazole derivatives containing furan, oxadiazole, triazole and thiadiazole moieties have been synthesized and then evaluated for their antioxidant and antiurease activities.

Results:

The results showed that all the tested benzimidazoles indicated remarkable urease inhibitory potentials with IC50 values ranging between 0.303±0.03 to 0.591±0.08 µM.

Conclusion:

In conclusion, synthesized benzimidazole derivatives showed good antioxidant and antiurease activities. Heterocyclic groups on benzimidazole nucleus enhance the activities.

3D-QSAR and Molecular Docking Studies on Oxadiazole Substituted Benzimidazole Derivatives: Validation of Experimental Inhibitory Potencies Towards COX-2

Background:

In past few decades, computational chemistry has seen significant advancements in design and development of novel therapeutics. Benzimidazole derivatives showed promising anti-inflammatory activity through the inhibition of COX-2 enzyme.

Objective:

The structural features necessary for COX-2 inhibitory activity for a series of oxadiazole substituted benzimidazoles were explored through 3D-QSAR, combinatorial library generation (Combi Lab) and molecular docking.

Methods:

3D-QSAR (using kNN-MFA (SW-FB) and PLSR (GA) methods) and Combi Lab studies were performed by using VLife MDS Molecular Design Suite. The molecular docking study was performed by using AutoDockVina.

Results:

Significant QSAR models generated by PLSR exhibited r2 = 0.79, q2 = 0.68 and pred_r2 = 0. 84 values whereas kNN showed q2 = 0.71 and pred_r2 = 0.84. External validation of developed models by various parameters assures their reliability and predictive efficacy. A library of 72 compounds was generated by combinatorial technique in which 11 compounds (A1-A5 and B1-B6) showed better predicted biological activity than the most active compound 27 (pIC50 = 7.22) from the dataset. These compounds showed proximal interaction with amino acid residues like TYR355 and/or ARG120 on COX-2(PDB ID: 4RS0).

Conclusion:

The present work resulted in the design of more potent benzimidazoles as COX-2 inhibitors with good interaction as compared to reference ligand. The results of the study may be helpful in the development of novel COX-2 inhibitors for inflammatory disorders.

Synthesis, characterization and biological evaluation of novel benzimidazole derivatives

In search of achieving less toxic and more potent chemotherapeutics, three novel heterocyclic benzimidazole derivatives: 2-(1H-benzo[d]imidazol-2-yl)-4-chlorophenol (BM1), 4-chloro-2-(6-methyl-1H-benzo[d]imidazol-2-yl)phenol (BM2) and 4-chloro-2-(6-nitro-1H-benzo[d]imidazol-2-yl)phenol (BM3) with DNA-targeting properties, were synthesized and fully characterized by important physicochemical techniques. The DNA binding properties of the compounds were investigated by UV-Visible absorption titrations and thermal denaturation experiments. These molecules exhibited a good binding propensity to fish sperm DNA (FS-DNA), as evident from the high binding constants (K_b) values: 1.9 × 10⁵, 1.39 × 10⁵ and 1.8 × 10⁴ M^‒1 for BM1, BM2 and BM3, respectively. Thermal melting studies of DNA further validated the absorption titration results and best interaction was manifested by BM1 with ΔT_m = 4.96 °C. The experimental DNA binding results were further validated theoretically by molecular docking study. It was confirmed that the molecules (BM1-BM3) bind to DNA via an intercalative and groove binding mode. The investigations showed a correlation between binding constants and energies obtained experimentally and through molecular docking, indicating a binding preference of benzimidazole derivatives with the minor groove of DNA. BM1 was the preferential candidate for DNA binding because of its flat structure, π-π interactions and less steric hindrance. To complement the DNA interaction, antimicrobial assays (antibacterial & antifungal) were performed. It was observed that compound BM2 showed promising activity against all bacterial strains (Micrococcus luteus, Staphylococcus aureus, Enterobacter aerogenes and Escherichia coli) and fungi (Aspergillus flavus, Aspergillus fumigatus and Fusarium solani), while rest of the compounds were active against selective strains. The MIC values of BM2 were found to be in the range of 12.5 ± 2.2-25 ± 1.5 µg/mL. Thus, the compound BM2 was found to be the effective DNA binding antimicrobial agent. Furthermore, the preliminary cytotoxic properties of synthesized compounds were evaluated by brine shrimps lethality assay to check their nontoxic nature towards healthy normal cells.Communicated by Ramaswamy H. Sarma.

Step-economical synthesis of 3-amido-2-quinolones by dendritic copper powder-mediated one-pot reaction

The one-pot protocol by the dendritic copper powder-mediated Knoevenagel condensation/annelation is delineated here for the synthesis of 3-amido-2-quinolones. It is practical with moisture tolerance and easy setup, and is compatible with many functional groups under mild conditions. This method was applied for the preparation of the key intermediates of biologically relevant 3-amido-2-quinolones.

Antimicrobial potential of 1H-benzo[d]imidazole scaffold: a review

Background

Benzimidazole is a heterocyclic moiety whose derivatives are present in many of the bioactive compounds and posses diverse biological and clinical applications. Benzimidazole agents are the vital pharmacophore and privileged sub-structures in chemistry of medicine. They have received much interest in drug discovery because benzimidazoles exhibited enormous significance. So attempts have been made to create repository of molecules and evaluate them for prospective inherent activity. They are extremely effective both with respect to their inhibitory activity and favorable selectivity ratio.

Conclusion

Benzimidazole is most promising category of bioactive heterocyclic compound that exhibit a wide variety of biological activities in medicinal field. The present review only focus on antimicrobial activity of reported benzimidazole derivatives may serve as valuable source of information for researchers who wish to synthesize new molecules of benzimidazole nucleus which have immense potential to be investigated for newer therapeutic possibilities.

Oxalic/malonic acids as carbon building blocks for benzazole, quinazoline and quinazolinone synthesis

Oxalic/malonic acids as CH/C₂H₃ carbon building blocks for the synthesis of 2-substituted and un-substituted benzazoles, quinazolines and quinazolinones.

Oxone-mediated annulation of 2-aminobenzamides and 1,2-diaminobenzenes withsec-aminesviaimine-N-oxides: new syntheses of 2,3-dihydroquinazolin-4(1H)-ones and 1H-benzimidazoles

Synthesis of 2,3-dihydroquinazolin-4(1H)-ones and 1H-benzimidazoles by reaction of imine-N-oxides with 2-aminobenzamides and 1,2-diaminobenzenes is described.

New (3-(1H-benzo[d]imidazol-2-yl))/(3-(3H-imidazo[4,5-b]pyridin-2-yl))-(1H-indol-5-yl)(3,4,5-trimethoxyphenyl)methanone conjugates as tubulin polymerization inhibitors

A series of new (3-(1H-benzo[d]imidazol-2-yl))/(3-(3H-imidazo[4,5-b]pyridin-2-yl))-(1H-indol-5-yl)(3,4,5-trimethoxyphenyl)methanone conjugates 4-6(a-i) were synthesized and evaluated for their antiproliferative activity on selected human cancer cell lines such as prostate (DU-145), lung (A549), cervical (HeLa) and breast (MCF-7). Most of these conjugates showed considerable cytotoxicity with IC₅₀ values ranging from 0.54 to 31.86 μM. Among them, compounds 5g and 6f showed significant activity against human prostate cancer cell line DU-145 with IC₅₀ values of 0.68 μM and 0.54 μM, respectively. Tubulin polymerization assay and immunofluorescence analysis results suggest that these compounds effectively inhibit microtubule assembly formation in DU-145. Further, the apoptosis-inducing ability of these derivatives (5g and 6f) was confirmed by Hoechst staining, measurement of mitochondrial membrane potential and ROS generation and annexin V-FITC assays.

Species-Specific Inactivation of Triosephosphate Isomerase from Trypanosoma brucei: Kinetic and Molecular Dynamics Studies

Human African Trypanosomiasis (HAT), a disease that provokes 2184 new cases a year in Sub-Saharan Africa, is caused by Trypanosoma brucei. Current treatments are limited, highly toxic, and parasite strains resistant to them are emerging. Therefore, there is an urgency to find new drugs against HAT. In this context, T. brucei depends on glycolysis as the unique source for ATP supply; therefore, the enzyme triosephosphate isomerase (TIM) is an attractive target for drug design. In the present work, three new benzimidazole derivatives were found as TbTIM inactivators (compounds 1, 2 and 3) with an I₅₀ value of 84, 82 and 73 µM, respectively. Kinetic analyses indicated that the three molecules were selective when tested against human TIM (HsTIM) activity. Additionally, to study their binding mode in TbTIM, we performed a 100 ns molecular dynamics simulation of TbTIM-inactivator complexes. Simulations showed that the binding of compounds disturbs the structure of the protein, affecting the conformations of important domains such as loop 6 and loop 8. In addition, the physicochemical and drug-like parameters showed by the three compounds suggest a good oral absorption. In conclusion, these molecules will serve as a guide to design more potent inactivators that could be used to obtain new drugs against HAT.

Design, synthesis and biological evaluation of chrysin benzimidazole derivatives as potential anticancer agents

A series of chrysin benzimidazole derivatives were synthesised and evaluated for their anticancer activity in the search for potential anticancer agents. Among them, compound 18 displayed the most potent anti-proliferative activity against MFC cells with IC₅₀ values of 25.72 ± 3.95 μM. The flow cytometry results displayed that compound 18 induced apoptosis of MFC cells in a dose-dependent manner and caused the cell cycle to be arrested in the G0/G1 phase. Furthermore, the preliminary anticancer activity in vivo was also studied in tumour-bearing mice, and the compound 18 exerted good inhibition effect on tumour growth. These results suggested that compound 18 had good anticancer activity, which could be a potential anticancer agent after further optimisation and evaluation.

Imidazoles as potential anticancer agents

Cancer is a black spot on the face of humanity in this era of science and technology. Presently, several classes of anticancer drugs are available in the market, but issues such as toxicity, low efficacy and solubility have decreased the overall therapeutic indices. Thus, the search for new promising anticancer agents continues, and the battle against cancer is far from over. Imidazole is an aromatic diazole and alkaloid with anticancer properties. There is considerable interest among scientists in developing imidazoles as safe alternatives to anticancer chemotherapy. The present article describes the structural, chemical, and biological features of imidazoles. Several classes of imidazoles as anticancer agents based on their mode of action have been critically discussed. A careful observation has been made into pharmacologically active imidazoles with better or equal therapeutic effects compared to well-known imidazole-based anticancer drugs, which are available on the market. A brief discussion of the toxicities of imidazoles has been made. Finally, the current challenges and future perspectives of imidazole based anticancer drug development are conferred.

Microwave-Assisted Synthesis of Diversely Substituted Quinoline-Based Dihydropyridopyrimidine and Dihydropyrazolopyridine Hybrids

An efficient, catalyst-free, and one-pot three-component procedure for the synthesis of novel and nitrogen rich dihydropyrido[2,3-d]pyrimidines and dihydro-1H-pyrazolo[3,4-b]pyridines bearing a quinoline pharmacophore fragment is provided. Reactions proceeded in DMF under microwave irradiation of three-component mixtures of formyl-quinoline derivatives, primary heterocyclic amines and cyclic 1,3-diketones. Interestingly, when conventional heating at reflux was used for the starting 5-amino-1-phenylpyrazole, the corresponding aromatized pyrazolopyridines were obtained as the main products. Single crystal X-ray analysis confirmed unequivocally the structure of both the dihydro- and aromatized products.

Design and synthesis of novel phenyl -1, 4-beta-carboline-hybrid molecules as potential anticancer agents

A series of beta-carbolines with other heterocycles linked by phenyl ring has been designed and synthesized. The key intermediates 3 and 5 were synthesized by condensing tryptamine and teraldehyde via Pictet- Spengler method. All the newly synthesized compounds were tested for their anticancer activity against sixty human cell lines at NCI. The five dose results of compounds 3 and 7a showed enhancement of anticancer activity (GI₅₀ values range from 1.00 to 7.10 μM) against all the cell lines in comparison with some of earlier molecules. In addition to this protein binding and CT-DNA intercalation studies showed molecules are highly potential. The molecular docking studies, which support the multiple mode of interaction with DNA, moreover the synthesized compounds 3 and 7a are more potential and possess drug -like nature.

Synthesis, Crystal Study, and Anti-Proliferative Activity of Some 2-Benzimidazolylthioacetophenones towards Triple-Negative Breast Cancer MDA-MB-468 Cells as Apoptosis-Inducing Agents

On account of its poor prognosis and deficiency of therapeutic stratifications, triple negative breast cancer continues to form the causative platform of an incommensurate number of breast cancer deaths. Aiming at the development of potent anticancer agents as a continuum of our previous efforts, a novel series of 2-((benzimidazol-2-yl)thio)-1-arylethan-1-ones 5a–w was synthesized and evaluated for its anti-proliferative activity towards triple negative breast cancer (TNBC) MDA-MB-468 cells. Compound 5k was the most active analog against MDA-MB-468 (IC₅₀ = 19.90 ± 1.37 µM), with 2.1-fold increased activity compared to 5-fluorouracil (IC₅₀ = 41.26 ± 3.77 µM). Compound 5k was able to induce apoptosis in MDA-MB-468, as evidenced by the marked boosting in the percentage of florecsein isothiocyanate annexin V (Annexin V–FITC)-positive apoptotic cells (upper right (UR) + lower right (LR)) by 2.8-fold in comparison to control accompanied by significant increase in the proportion of cells at pre-G1 (the first gap phase) by 8.13-fold in the cell-cycle analysis. Moreover, a quantitative structure activity relationship (QSAR) model was established to investigate the structural requirements orchestrating the anti-proliferative activity. Finally, we established a theoretical kinetic study.

Synthesis, Spectroscopic, X-ray Diffraction and DFT Studies of Novel Benzimidazole Fused-1,4-Oxazepines

A series of benzimidazole-tethered oxazepine heterocyclic hybrids has been synthesized in good to excellent yields from an N-alkylated benzimidazole 2-carboxaldehyde, which in turn was accomplished from o-phenylenediamine in three good yielding steps. The calculated molecular structure of compounds 2-methyl-4-(2-((phenylimino)methyl)-1H-benzo-[d]imidazol-1-yl)-butan-2-ol 9 and 10 3,3-dimethyl-N-phenyl-1,2,3,5-tetrahydrobenzo-[4,5]imidazo[2,1-c][1,4]oxazepin-5-amine using the B3LYP/6-31 G(d, p) method were found to agree well with their X-ray structures. The charge distributions at the different atomic sites were computed using the natural bond orbital (NBO) method. The regions of electrophilic and nucleophilic reactivity were shown using a molecular electrostatic potential (MEP) map. In addition, the frontier molecular orbitals of these compounds were discussed at the same level of theory. Nonlinear optical (NLO) properties have also been investigated by computational hyperpolarizability studies, and it was found that Compound 9 is the best candidate for NLO applications.