A study on the antioxidant capacities of some benzimidazoles in rat tissues

Synthesis and anti-inflammatory activity of benzimidazole derivatives; an in vitro, in vivo and in silico approach

Many non-steroidal anti-inflammatory drugs (NSAIDs) concurrently inhibit both COX-1 and COX-2, with a preference for specifically targeting COX-2 due to its significant involvement in various pathologies. In addition to COX enzymes, several other targets, including Aldose reductase, Aldo-ketoreductase family 1-member C2, and Phospholipase A2, have been identified as contributors to inflammation and a myriad of other diseases. In this context, a series of 2-substituted benzimidazole derivatives was synthesized and assessed for their anti-inflammatory potential through both in vitro and in vivo assays. Molecular docking studies were conducted to elucidate the mechanism of action of these compounds against COX enzymes and other therapeutic targets associated with NSAIDs, such as Aldose reductase, AIKRC, and Phospholipase A2. Among the synthesized compounds, B2, B4, B7, and B8 demonstrated IC50 values lower than the standard ibuprofen, as determined by the Luminol-enhanced chemiluminescence assay. Validation of these findings was achieved through an in vivo carrageenan-induced mice paw edema model, confirming a comparable anti-inflammatory effect to diclofenac sodium observed in vitro. Notably, these compounds exhibited significant binding affinity with all therapeutic targets investigated in this study. These results suggest that the newly synthesized derivatives possess noteworthy anti-inflammatory potential, warranting further exploration for the development of novel multi-targeting inhibitors.

Selective Synthesis of Benzimidazoles from o-Phenylenediamine and Aldehydes Promoted by Supported Gold Nanoparticles

We investigated the catalytic efficacy of supported gold nanoparticles (AuNPs) towards the selective reaction between o-phenylenediamine and aldehydes that yields 2-substituted benzimidazoles. Among several supported gold nanoparticle platforms, the Au/TiO₂ provides a series of 2-aryl and 2-alkyl substituted benzimidazoles at ambient conditions, in the absence of additives and in high yields, using the mixture CHCl₃:MeOH in ratio 3:1 as the reaction solvent. Among the AuNPs catalysts used herein, the Au/TiO₂ containing small-size nanoparticles is found to be the most active towards the present catalytic methodology. The Au/TiO₂ can be recovered and reused at least five times without a significant loss of its catalytic efficacy. The present catalytic synthetic protocol applies to a broad substrate scope and represents an efficient method for the formation of a C–N bond under mild reaction conditions. Notably, this catalytic methodology provides the regio-isomer of the anthelmintic drug, Thiabendazole, in a lab-scale showing its applicability in the efficient synthesis of such N-heterocyclic molecules at industrial levels.

An efficient synthesis of novel di-heterocyclic benzazole derivatives and evaluation of their antiproliferative activities

A series of unsymmetrical nine di-heterocyclic compounds of benzazole derivatives were synthesized at one step via cyclization reaction. The compounds evaluated for in vitro cytotoxic activity against A549, A498, HeLa, and HepG2 cancer cell lines. The biological evaluation results show that 23, 26 and 29 exhibit better activity against HepG2 and HeLa cancer cell lines. Compound 23 also showed good activity against A549, and A498 cancer cell lines. The analogs were further performed molecular docking studies against human cytochrome P450 2C8 monooxygenase enzyme, calculated some theoretical quantum parameters, ADMET descriptor and molecular electrostatic potential analysis. The strategy applied in this research work may act as a perspective for the rational design of potential anticancer drugs. Communicated by Ramaswamy H. Sarma.

Novel Mixed Complexes Derived from Benzoimidazolphenylethanamine and 4-(Benzoimidazol-2-yl)aniline: Synthesis, Characterization, Antibacterial Evaluation and Theoretical Prediction of Toxicity

Benzoimidazolphenylethanamine (BPE) has been synthesized using condensation reaction from o-phenyldiamine and L-phenylalanine. Some metal complexes have been synthesized from 4-(benzoimidazol-2-yl)aniline, benzoimidazolylphenylethanamine and cadmium(II), tin(II), copper(II) and nickel(II) metal in a molar ratio (1:1:1). All new metal complexes were characterized by spectroscopic data of FTIR, UV-visible electronic absorption, X-ray powder diffraction and thermal analysis. Spectra analysis of the mixed metal complexes showed the coordination of ligands to the metal ions via nitrogen atoms. The XRD powder showed that metal complexes have a monoclinic system. The preliminary tested in vitro antibacterial activities of Sn(II) complex was assayed against four bacterial isolates namely Micrococcus luteus, Staphylococcus aureus as Gram-positive, Pseudomonas aerugmosa and Escherichia coli.

Synthesis and Antifungal Potential of Some Novel Benzimidazole-1,3,4-Oxadiazole Compounds

Discovery of novel anticandidal agents with clarified mechanisms of action, could be a rationalist approach against diverse pathogenic fungal strains due to the rise of resistance to existing drugs. In support to this hypothesis, in this paper, a series of benzimidazole-oxadiazole compounds were synthesized and subjected to antifungal activity evaluation. In vitro activity assays indicated that some of the compounds exhibited moderate to potent antifungal activities against tested Candida species when compared positive control amphotericin B and ketoconazole. The most active compounds 4h and 4p were evaluated in terms of inhibitory activity upon ergosterol biosynthesis by an LC-MS-MS method and it was determined that they inhibited ergosterol synthesis concentration dependently. Docking studies examining interactions between most active compounds and lanosterol 14-α-demethylase also supported the in vitro results.

Synthesis, anti-microbial activity, cytotoxicity of some novel substituted (5-(3-(1H-benzo[d]imidazol-2-yl)-4-hydroxybenzyl)benzofuran-2-yl)(phenyl)methanone analogs

Background

There is a dire need for the discovery and development of new antimicrobial agents after several experiments for a better resistance of microorganisms towards antimicrobial agents become a serious health problem for a few years in the past. As benzimidazole possess various types of biological activities, it has been synthesized, in the present study, a new series of (5-(3-(1H-benzo[d]imidazol-2-yl)-4-hydroxybenzyl)benzofuran-2-yl)(phenyl)methanone analogs by using the condensation and screened for its in vitro antimicrobial activity and cytotoxicity.

Results

The synthesized (5-(3-(1H-benzo[d]imidazol-2-yl)-4-hydroxybenzyl) benzofuran-2-yl)(phenyl)methanone analogs were confirmed by IR, ¹H and ¹³C-NMR, MS spectra and HRMS spectral data. The synthesized compounds were evaluated for their in vitro antimicrobial potential against Gram-positive (Bacillus subtilis, Bacillus megaterium, Staph aureus and Streptococcus pyogenes), Gram-negative (Escherichia coli, Proteus vulgaris, Proteus mirabilis and Enterobacter aerogenes) bacterial and fungal (Aspergillus niger, Candida albicans, Fusarium oxysporum, Fusarium solani) strains by disc diffusion method and the minimum inhibitory concentration (MIC) in which it has been recorded in microgram per milliliter in comparison to the reference drugs, ciprofloxacin (antibacterial) and nystatin (antifungal). Further, the cytotoxicity (IC₅₀ value) has also been assessed on human cervical (HeLa), Supt1 cancer cell lines by using MTT assay.

Conclusions

The following screened compounds (4d), (4f), (4g), (4k), (4l), (4o) and (4u) were found to be the best active against all the tested bacterial and fungal strains among all the demonstrated compounds of biological study. The MIC determination was also carried out against bacteria and fungi, the compounds (4f) and (4u) are found to be exhibited excellent potent against bacteria and fungi respectively. The compounds (4f) and (4u) were shown non-toxic in nature after screened for cytotoxicity against the cancer cell lines of human cervical (HeLa) and Supt1. Additionally, structure and antibacterial activity relationship were also further supported by in silico molecular docking studies of the active compounds against DNA topoisomerase.

Electronic supplementary material

The online version of this article (10.1186/s13065-017-0364-3) contains supplementary material, which is available to authorized users.

Recent advances in the synthesis of benzimidazol(on)es via rearrangements of quinoxalin(on)es

The review describes all the quinoxaline-benzimidazole rearrangements as a whole and the new quinoxalinone-benzimidazol(on)e rearrangements in particular when exposed to nucleophilic rearrangements which can be used for the synthesis of various biheterocyclic motifs.

A novel role of transient receptor potential mucolipin1 (TRPML1) in protecting against imidazole-induced cytotoxicity

Lysosomotropic amines cause serious side effects such as cytoplasmic vacuolation and cell death. TRPML1 (also known as mucolipin1), a member of the transient receptor potential (TRP) protein family, may regulate fusion/fission of vesicles along the endocytic pathway and some aspects of lysosomal ion homeostasis. Nevertheless, it is still unknown whether TRPML1 is involved in death of mammalian cells induced by lysosomotropic agents. In this study, imidazole was used as a model to investigate the role of TRPML1 in the cytotoxicity of lysosomotropic agents. Overexpression of wild-type TRPML1 inhibited imidazole-induced vacuole formation and cell death in human endometrial adenocarcinoma (HEC-1B) cells. In contrast, siRNA-mediated TRPML1 knockdown increased the cell death induced by imidazole. Bafilomycin A1 raises the pH of acidic organelles and therefore suppresses accumulation of weak bases in them. Similarly, lysosomal pH was raised in TRPML1-overexpressing cells; therefore, we inferred that TRPML1 protected against imidazole toxicity by regulating the pH of acidic organelles. We concluded that TRPML1 had a novel role in protecting against lysosomotropic amine toxicity.

Construction and screening of 2-aryl benzimidazole library identifies a new antifouling and antifungal agent

Library of 2-aryl benzimidazole core inspired from marine natural products, is identified and synthesized to explore antifouling/antifungal properties for the first time. Our results reveal that the 2-aryl substituent on the benzimidazole core had strong impact on their biological profile.

Conjugation of benzylvanillin and benzimidazole structure improves DNA binding with enhanced antileukemic properties

Benzyl-o-vanillin and benzimidazole nucleus serve as important pharmacophore in drug discovery. The benzyl vanillin (2-(benzyloxy)-3-methoxybenzaldehyde) compound shows anti-proliferative activity in HL60 leukemia cancer cells and can effect cell cycle progression at G2/M phase. Its apoptosis activity was due to disruption of mitochondrial functioning. In this study, we have studied a series of compounds consisting of benzyl vanillin and benzimidazole structures. We hypothesize that by fusing these two structures we can produce compounds that have better anticancer activity with improved specificity particularly towards the leukemia cell line. Here we explored the anticancer activity of three compounds namely 2-(2-benzyloxy-3-methoxyphenyl)-1H-benzimidazole, 2MP, N-1-(2-benzyloxy-3-methoxybenzyl)-2-(2-benzyloxy-3-methoxyphenyl)-1H-benzimidazole, 2XP, and (R) and (S)-1-(2-benzyloxy-3-methoxyphenyl)-2, 2, 2-trichloroethyl benzenesulfonate, 3BS and compared their activity to 2-benzyloxy-3-methoxybenzaldehyde, (Bn1), the parent compound. 2XP and 3BS induces cell death of U937 leukemic cell line through DNA fragmentation that lead to the intrinsic caspase 9 activation. DNA binding study primarily by the equilibrium binding titration assay followed by the Viscosity study reveal the DNA binding through groove region with intrinsic binding constant 7.39 µM/bp and 6.86 µM/bp for 3BS and 2XP respectively. 2XP and 3BS showed strong DNA binding activity by the UV titration method with the computational drug modeling showed that both 2XP and 3BS failed to form any electrostatic linkages except via hydrophobic interaction through the minor groove region of the nucleic acid. The benzylvanillin alone (Bn1) has weak anticancer activity even after it was combined with the benzimidazole (2MP), but after addition of another benzylvanillin structure (2XP), stronger activity was observed. Also, the combination of benzylvanillin with benzenesulfonate (3BS) significantly improved the anticancer activity of Bn1. The present study provides a new insight of benzyl vanillin derivatives as potential anti-leukemic agent.

1-Phenyl-2-p-tolyl-1H-benzimidazole

In the title compound, C20H16N2, the benzimidazole ring system forms dihedral angles of 28.50 (7) and 72.44 (7)° with the tolyl and phenyl rings, respectively. In the crystal, mol-ecules are linked into chains along the a-axis direction by weak C-H⋯N inter-actions. The crystal structure also features C-H⋯π inter-actions.

Synthesis and evaluation of antioxidant properties of novel 2-[2-(4-chlorophenyl) benzimidazole-1-yl]-N-(2-arylmethylene amino) acetamides and 2-[2-(4-chlorophenyl) benzimidazole-1-yl]-N-(4-oxo-2-aryl-thiazolidine-3-yl) acetamides-I

Our approach was to synthesize and examine the antioxidant properties of some new 2-[2-(4-chlorophenyl)benzimidazole-1-yl]-N-(2-arylmethyleneamino) acetamide (1-18) and 2-[2-(4-chlorophenyl)benzimidazole-1-yl]-N-(4-oxo-2-aryl-thiazolidine-3-yl)acetamide (1t-18t) derivatives. Their in vitro effects on rat liver microsomal NADPH-dependent lipid peroxidation levels (LP assay) and microsomal ethoxyresorufin O-deethylase activities (EROD assay) were determined. The free radical scavenging properties of the compounds were also examined in vitro determining the interaction of 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical. The compounds showed significant effects in the above tests.

Ethyl 1-sec-butyl-2-p-tolyl-1H-benzimidazole-5-carboxyl-ate

In the title compound, C₂₁H₂₄N₂O₂, the butyl group is disordered over two orientations with refined site occupancies of 0.883 (3) and 0.117 (3). The dihedral angle between the mean plane of benzimidazole ring system and the benzene ring is 39.32 (4)° and the dihedral angle between the mean plane of carboxyl­ate group and the benzimidazole ring system is 6.87 (5)°. A weak intra­molecular C—H⋯π inter­action may have some influence on the conformation of the mol­ecule. In the crystal structure, mol­ecules are linked into infinite chains along the b axis by weak inter­molecular C—H⋯O hydrogen bonds.

Synthesis and antioxidant properties of novel benzimidazoles containing substituted indole or 1,1,4,4-tetramethyl-1,2,3,4-tetrahydro-naphthalene fragments

Some 6-fluoro-5-substituted-benzimidazole derivatives in which indole and 1,1,4,4-tetramethyl-1,2,3,4-tetrahydro-naphthalene groups were attached to the 2-position of the benzimidazole ring were synthesized and tested for antioxidant properties in vitro. Almost all the synthesized compounds at the 10(-3) M concentrations showed superoxide anion scavenging activity. Compounds 5, 3, 9, 4, 17 and 13 have strong inhibitory effects on superoxide anion formation (98%, 93%, 91%, 88%, 85% and 81%, respectively) at 10(-3) M concentration and these results are better than 30 IU of superoxide dismutase (SOD) (76%). Compound 11 is the most effective scavenger of 2,2-diphenyl-1-picrylhydrazyl (DPPH) stable free radical at 10(-3)M (61%) concentration.

Synthesis and evaluation ofin vitroantioxidant capacities of some benzimidazole derivatives

New, except 1d, melatonin analogue benzimidazole derivatives were synthesized and characterized in the present study. The potential role of melatonin as an antioxidant by scavenging and detoxifying ROS raised the possibility that compounds that are analogous to melatonin can also be used for their antioxidant properties. Therefore the antioxidant effects of the newly synthesized compounds were investigated in vitro by means of their inhibitory effect on hydrogen peroxide-induced erythrocyte membrane lipid peroxidation (EMLP) and on various erythrocyte antioxidant enzymes viz. superoxide dismutase (SOD), catalase (CAT) and glucose-6-phosphate dehydrogenase (G6PD). The synthesized benzimidazole derivatives showed remarkable antioxidant activity in vitro in the H2O2-induced EMLP system. Furthermore their effects on various antioxidant enzymes are discussed and evaluated from the perspective of structure- activity relationships.

Synthesis, characterization and evaluation of benzimidazole derivative and its precursors as inhibitors of MDA-MB-231 human breast cancer cell proliferation

A novel series of trisubstituted benzimidazole and its precursors (3-7) were synthesised and characterized by using 1H NMR, LC/MS, FTIR and elemental analysis techniques. The title compounds were evaluated for inhibition against MDA-MB-231 breast cancer cell proliferation. The results revealed that the compound N-(4-cyano-3-(trifluoromethyl) phenyl)-4-fluoro-3-nitrobenzamide (3) was the potent inhibitor.

Pro-apoptotic activity of imidazole derivatives mediated by up-regulation of Bax and activation of CAD in Ehrlich Ascites Tumor cells

In this study we report that, imidazole derivatives can induce apoptosis in Ehrlich ascites tumor (EAT) cells, which is clearly evident from annexin-V staining, flow cytometric analysis of cell cycle phase distribution and DNA fragmentation. Delineating further into molecular mechanisms leading to apoptosis of EAT cells, we observed that imidazole derivatives induce tumor cell death by the up-regulation of proto-oncoprotein Bax, release of cytochrome c from the mitochondria which activates caspase-3 and activated caspase-3 activates CAD (Caspase Activated DNase) causes DNA fragmentation. The status of Bcl-2 remains unaltered in EAT cells, and the under expression of Bcl-2 and up-regulation of Bax resulted in the increase of Bax: Bcl-2 ratio suggesting that Bcl-2 family involved in the control of apoptosis. These results suggest a further possible clinical application of imidazole derivatives as pro-apoptotic agent in association with conventional chemotherapeutic agents.

Investigation of antioxidant vitamins (A, E, C) and lipid peroxidation levels in rats injected N-(1,3-benzothiazol-2-yl)-N-(4,5-dihydro-1H-imidazol-2-yl) amine

The present study examined the influence of synthetic N-(1,3-benzothiazol-2-yl)-N-(4,5-dihydro-1H-imidazol-2-yl) amine (2-Amdz) on levels of vitamins A, E and C and malondialdehyde (MDA) in rats. A total of 30 rats, divided into two groups, were used in the study. The control group was given only a subcutaneous injection of 250 µL 75% ethanol, every other day. The other group of rats was administered a subcutaneous injection of 2-Amdz (25 mg kg^-1, dissolved in 250 µL of 75% ethanol). Injections were continued for 16 days. After the application of 2-Amdz for 16 days, the serum levels of vitamins A, E and C and malondialdehyde (MDA) were determined by HPLC. The serum vitamin A, E, and C levels decreased significantly compared to controls (p<0.05) whereas serum MDA levels were higher than control levels (p<0.005). As a result, it can be suggested that 2-Amdz induced a severe stress and more importantly, increased the amount of free radicals and significantly decreased the levels of serum antioxidant vitamins.

Synthesis and antioxidant properties of some novel benzimidazole derivatives on lipid peroxidation in the rat liver

Some benzimidazole derivatives namely 1-[(substituted thiocarbamoylhydrazine carbonyl) methyl]-2-phenyl-1H-benzimidazoles (1a-13a), N-[(2-phenylbenzimidazol-1-yl methyl)-[1,3,4]-thiadiazole-2-yl]-substituted phenyl amines (1b-13b) and 5-(2-phenyl benzimidazol-1-yl-methyl)-4-substituted phenyl-4H-1,2,4-triazole-3-thiones (1c-13c) were synthesized, and their in vitro effects on the rat liver microsomal NADPH-dependent lipid peroxidation (LP) levels were determined. The most active compound 10a caused an 84% inhibition of LP at 10(-3) M, which is better than that of butylated hydroxytoluene (BHT) (65%).