Synthesis and biological evaluation of novel benzimidazole derivatives and their binding behavior with bovine serum albumin

Hybrids of Benzimidazole-oxadiazole: A New Avenue for Synthesis, Pharmacological Activity and Recent Patents for the Development of More Effective Ligands

BACKGROUND

Two significant families of compounds i.e. 1,3,4-oxadiazole and benzimidazole, have undergone extensive investigation into their pharmacological characteristics and possible therapeutic applications. Both classes have shown their potential in a variety of applications, and because of their synergistic interactions, they may have an even better therapeutic impact when combined.

OBJECTIVES

To produce a specific molecule with potent therapeutic properties, it is now common methods to combine at least two pharmacophores. This facilitates interaction with several targets, enhances biological functions, or eliminates adverse effects associated with them.

CONCLUSION

The synthesis of benzimidazole-1,3,4-oxadiazole hybrid compounds has recently involved the use of several synthetic techniques, all of which are detailed in the literature along with the advantages and disadvantages. It has been noted that the structure-activity relationship relates their pharmacological actions to their molecular structure. In order to set the stage for future research, the study aims to provide researchers with an effective toolbox and an understanding of benzimidazole and 1,3,4-oxadiazole hybrid compounds.

Synthesis, Antimicrobial Evaluation, and Interaction of Emodin Alkyl Azoles with DNA and HSA

OBJECTIVE

This study aimed to overcome the growing antibiotic resistance. Moreover, the new series of emodin alkyl azoles were synthesized.

METHOD

The novel emodin alkyl azoles were synthesized using commercial emodin and azoles by alkylation. The NMR and HRMS spectra were employed to confirm the structures of novel prepared compounds. The in vitro antibacterial and antifungal activities of the prepared emodin compounds were studied by the 96-well plate method. The binding behavior between emodin 4-nitro imidazole compound 3c and S. aureus DNA was researched using an ultraviolet-visible spectrophotometer. Furthermore, fluorescence spectrometry was used to explore the interaction with human serum albumin (HSA).

RESULTS

The in vitro antimicrobial results displayed that compound 3c gave relatively strong activities with MIC values of 4-16 μg/mL. Notably, this compound exhibited 2-fold more potent activity against S. aureus (MIC = 4 μg/mL) and E. coli (MIC = 8 μg/mL) strains than clinical drug Chloromycin (MIC = 8 and 16 μg/mL). The UV-vis absorption spectroscopy showed that 4-nitro imidazole emodin 3c could form the 3c-DNA complex by intercalating into S. aureus DNA, inhibiting antimicrobial activities. The simulation results displayed that the emodin 3c and DNA complex were formed by hydrogen bonds. The spectral experiment demonstrated that compound 3c could be transported by human serum albumin (HSA) via hydrogen bonds. The molecular simulation found that the hydroxyl group and the nitroimidazole ring of the emodin compound showed an important role in transportation behavior.

CONCLUSION

This work may supply useful directions for the exploration of novel antimicrobial agents.

Emodin Alcohols: Design, Synthesis, Biological Evaluation and Multitargeting Studies with DNA, RNA, and HSA

OBJECTIVE

A series of novel emodin alcohols were designed and prepared in an effort to overcome the increasing microorganism resistance.

METHODS

Novel emodin alcohols were prepared from commercial emodin and different nitrogen-containing heterocycles via different synthetic strategies, such as O-alkylation and N-alkylation. The antimicrobial activity of synthesized emodin compounds was evaluated in vitro by a two-fold serial dilution technique. The interaction of emodin compound 3d with biomolecule was researched using UV-vis spectroscopic method and fluorescence spectroscopy.

RESULTS

Emodin compound 3d containing 2-methyl-5-nitro imidazole ring showed relatively good antimicrobial activity. Notably, it exhibited equivalent activity against S. aureus in comparison to the reference drug norfloxacin (MIC = 4 μg/mL). The combination of strong active compound 3d with reference drugs showed better antimicrobial activity with less dosage and a broader antimicrobial spectrum than their separate use. Further research displayed that emodin compound 3d could intercalate into S. aureus DNA to form the 3d-DNA complex, which might correlate with the inhibitory activity. The hydrogen bonds were found between S. aureus DNA gyrase and strong active compound 3d during the docking research, which were in accordance with the spectral experiment results. The interaction with yeast RNA of compound 3d could also form a complex via hydrogen bonds. The hydrogen bonds were found to play a major role in the transportation of emodin compound 3d by human serum albumin (HSA), as confirmed by molecular simulation.

CONCLUSION

This work provides a promising starting point to optimize the structures of emodin derivatives as potent antimicrobial agents.

Comprehensive Insights into Medicinal Research on Imidazole-Based Supramolecular Complexes

The electron-rich five-membered aromatic aza-heterocyclic imidazole, which contains two nitrogen atoms, is an important functional fragment widely present in a large number of biomolecules and medicinal drugs; its unique structure is beneficial to easily bind with various inorganic or organic ions and molecules through noncovalent interactions to form a variety of supramolecular complexes with broad medicinal potential, which is being paid an increasing amount of attention regarding more and more contributions to imidazole-based supramolecular complexes for possible medicinal application. This work gives systematical and comprehensive insights into medicinal research on imidazole-based supramolecular complexes, including anticancer, antibacterial, antifungal, antiparasitic, antidiabetic, antihypertensive, and anti-inflammatory aspects as well as ion receptors, imaging agents, and pathologic probes. The new trend of the foreseeable research in the near future toward imidazole-based supramolecular medicinal chemistry is also prospected. It is hoped that this work provides beneficial help for the rational design of imidazole-based drug molecules and supramolecular medicinal agents and more effective diagnostic agents and pathological probes.

Novel Structures of Functionalized Graphene Oxide with Hydrazide: Characterization and Bioevaluation of Antimicrobial and Cytocompatibility Features

Graphite was oxidized to graphene oxide and activated by thionyl chloride, for further covalently linking three hydrazides with potential biological activity. The obtained materials were characterized by scanning electron microscopy with energy dispersive spectroscopy, Fourier-transform infrared and Raman spectroscopies. The presence of various functional groups specific to graphene oxide (GO) functionalized with different hydrazides was confirmed by spectral data. The ratio between D- and G-bands, observed in Raman spectra, allowed for an evaluation of the disorder degree and the mean crystallite size of the samples. The micrographs highlighted that the samples lead to the occurrence of disorders, probably caused by the sp3 carbons, the formation of oxygen-containing functional groups in the basal planes, and by various structural defects. The new graphene oxide–hydrazide derivatives were tested for their antimicrobial and cytotoxicity activity. Their antimicrobial activity against planktonic and biofilm-embedded cells was inferior to that of free hydrazides, except for GO-3 against planktonic Escherichia coli and GO-2 against Pseudomonas aeruginosa biofilm, demonstrating that further optimization is needed to be able to exploit the huge potential of GO for developing potent antimicrobials.

Synthetic Approach to Potential Anticancer Benzimidazole Derivatives- A Review

Cancer is one of the deadliest diseases in many developed and developing countries. Continuous efforts are required for designing better therapeutic agents for the treatment of cancer with more efficacy, selectivity, and less toxicity. The fused heterocyclic ring system has been identified by several researchers as a privileged structure that can be used as a basis for drug discovery in medicinal chemistry. The hetero-aromatic bicyclic ring system acts as a pharmacophore in a wide range of drugs with therapeutic potential. According to studies in the literature, variously substituted benzimidazoles have distinct pharmacological profiles with multi-targeting ability, making them an important anchor for the production of novel therapeutic agents against complex cancers including breast cancer, skin cancer, and blood cancer. In this presented article we are discussed various synthetic methods for the synthesis of anticancer benzimidazoles and their derivatives in different solvent conditions, substrates, and various catalysts mainly those which are eco-friendly, and economical, which shows the anticancer activity. We also focused on various derivatives are under clinical trials containing Benzimidazole moiety.

Benzimidazole analogues as efficient arsenals in war against methicillin-resistance staphylococcus aureus (MRSA) and its SAR studies

Small molecule based inhibitors development is a growing field in medicinal chemistry. In recent years, different heterocyclic derivatives have been designed to counter the infections caused by multi-drug resistant bacteria. Indeed, small molecule inhibitors can be employed as an efficient antibacterial agents with different mechanism of action. Methicillin-resistant Staphylococcus aureus (MRSA) is becoming lethal to mankind due to easy transmission mode, rapid resistance development to existing antibiotics and affect difficult-to-treat skin and filmsy diseases. Benzimidazoles are a class of heterocyclic compounds which have capability to fight against MRSA. High biocompatibility of benzimidazoles, synergistic behaviour with antibiotics and their tunable physico-chemical properties attracted the researchers to develop new benzimidazole based antibacterial agents. The present review focus on recent developments of benzimidazole-hybrid molecules as anti MRSA agents and the results of in-vitro and in-vivo studies with possible mechanism of action and discussing structure-activity relationship (SAR) in different directions. Benzimdazoles act as DNA binding agents, enzyme inhibitors, anti-biofilm agents and showed synergistic effect with available antibiotics to achieve antibacterial activity against MRSA. This cumulative figures would help to design new benzimidazole-based MRSA growth inhibitors.

Design, Synthesis and Antimicrobial Evaluation of Novel Benzimidazole-incorporated Naphthalimide Derivatives As Salmonella typhimurium DNA Intercalators, and Combination Researches

OBJECTIVE

A series of novel benzimidazole-incorporated naphthalimide derivatives were designed and prepared to overcome the increasing antibiotic resistance.

METHOD

The target novel benzimidazole-incorporated naphthalimide derivatives were synthesized from commercial 4-bromo-1,8-naphthalic anhydride and o-phenylene diamine by aminolysis, N-alkylation, and so on. The antimicrobial activity of the synthesized compounds was evaluated in vitro by a two-fold serial dilution technique. The interaction of compound 10g with Salmonella typhimurium DNA was studied using UV-vis spectroscopic methods.

RESULTS

Compound 10g bearing a 2,4-dichlorobenzyl moiety exhibited the best antimicrobial activities in this series relatively, especially it gave the comparable action against Salmonella typhimurium compared to the reference drug Norfloxacin (MIC = 4 mg/mL). Further research showed that compound 10g could effectively intercalate into the Salmonella typhimurium DNA to form the 10g-DNA complex, which might correlate with the inhibitory activity. Molecular docking results demonstrated that naphthalimide compound 10g could interact with base-pairs of DNA hexamer duplex by p-p stacking. Additionally, the combinations of the solid active combination with clinical drugs gave better antimicrobial efficiency with less dosage and broader antimicrobial spectrum than the separated use alone. Notably, these combined systems were more sensitive to Fluconazole-insensitive M. ruber.

CONCLUSION

This work opened up a good starting point to optimize the structures of benzimidazole-incorporated naphthalimide derivatives as potent antimicrobial agents.

Recent advancements on Benzimidazole: A versatile scaffold in medicinal chemistry

Benzimidazole is nitrogen containing fused heterocycle which has been extensively explored in medicinal chemistry. Benzimidizole nucleus has been found to possess various biological activities such as anticancer, antimicrobial, anti-inflammatory, antiviral, antitubercular and antidiabetic. A number of benzimidazoles such as bendamustine, pantoprazole have been approved for the treatment of various illnesses whereas galeterone and GSK461364 are in clinical trials. The present review article gives an overview about the different biological activities exhibited by the benzimidazole derivatives as well as different methods used for the synthesis of benzimidazole derivatives for the past ten years.

Synthesis, Characterization and Bioassay of Novel Substituted 1-(3-(1,3-Thiazol-2-yl)phenyl)-5-oxopyrrolidines

Thiazole derivatives attract the attention of scientists both in the field of organic synthesis and bioactivity research due to their high biological activity. In the present study, thiazole ring was obtained by the interaction of 1-(4-(bromoacetyl)phenyl)-5-oxopyrrolidine-3-carboxylic acid with thiocarbamide or benzenecarbothioamide, as well as tioureido acid. A series of substituted 1-(3-(1,3-thiazol-2-yl)phenyl)-5-oxopyrrolidines with pyrrolidinone, thiazole, pyrrole, 1,2,4-triazole, oxadiazole and benzimidazole heterocyclic fragments were synthesized and their antibacterial properties were evaluated against Gram-positive strains of Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes and Gram-negative Pseudomonas aeruginosa, Escherichia coli and Salmonella enterica enteritidis. The vast majority of compounds exhibited between twofold and 16-fold increased antibacterial effect against the test-cultures when compared with Oxytetracycline.

Antimicrobial Potential of Benzimidazole Derived Molecules

Structural resemblance of benzimidazole nucleus with purine nucleus in nucleotides makes benzimidazole derivatives attractive ligands to interact with biopolymers of a living system. The most prominent benzimidazole compound in nature is N-ribosyldimethylbenzimidazole, which serves as an axial ligand for cobalt in vitamin B12. This structural similarity prompted medicinal chemists across the globe to synthesize a variety of benzimidazole derivatives and to screen those for various biological activities, such as anticancer, hormone antagonist, antiviral, anti-HIV, anthelmintic, antiprotozoal, antimicrobial, antihypertensive, anti-inflammatory, analgesic, anxiolytic, antiallergic, coagulant, anticoagulant, antioxidant and antidiabetic activities. Hence, benzimidazole nucleus is considered as a privileged structure in drug discovery, and it is exploited by many research groups to develop numerous compounds that are purported to be antimicrobial. Despite a large volume of research in this area, no novel benzimidazole derived compound has emerged as clinically effective antimicrobial drug. In the present review, we have compiled various reports on benzimidazole derived antimicrobials, classified as monosubstituted, disubstituted, trisubstituted and tetrasubstituted benzimidazoles, bisbenzimidazoles, fused-benzimidazoles, and benzimidazole derivative-metal complexes. The purpose is to collate these research reports, and to generate a generalised outlay of benzimidazole derived molecules that can assist the medicinal chemists in selecting appropriate combination of substituents around the nucleus for designing potent antimicrobials.

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.

Synthesis, structure and biological evaluation of mixed ligand oxidovanadium(iv) complexes incorporating 2-(arylazo)phenolates

Synthesis and characterization of mixed ligand oxidovanadium(iv) complexes [V^IVO(L^1–4)(L^NN)] incorporating arylazo ligands: evaluation of DNA/BSA interaction and cytotoxicity activity.

Design and synthesis of a new series of low toxic naphthalimide platinum(IV) antitumor complexes with dual DNA damage mechanism

Naphthalimide platinum(IV) antitumor complexes with potential dual DNA damage mechanism were designed, synthesized and evaluated for antitumor activities. The incorporation of DNA targeted naphthalimide group to the platinum(IV) system exerts much positive impacts on their antitumor efficacy. The mechanism research reveals that the title compounds could interact with dsDNA in platinum(IV) form via the naphthalimide group and cause DNA lesion. The further reduction would release platinum(II) complexes and naphthalimide acids which would induce remarkable secondary damage to DNA. Furthermore, the naphthalimide platinum(IV) compounds could combine with human serum albumin via electrostatic force, which are favourable for their storage and transport in blood. Moreover, the title compounds exhibit higher accumulation in tumor cells, and exert lower toxic and higher safe properties than oxaliplatin in vivo.

Synthesis, Characterization, Cytotoxic Activity, and Interactions with CT-DNA and BSA of Cationic Ruthenium(II) Complexes Containing Dppm and Quinoline Carboxylates

The complexes cis-[Ru(quin)(dppm)₂]PF₆ and cis-[Ru(kynu)(dppm)₂]PF₆ (quin = quinaldate; kynu = kynurenate; dppm = bis(diphenylphosphino)methane) were prepared and characterized by elemental analysis, electronic, FTIR, ¹H, and ³¹P{¹H} NMR spectroscopies. Characterization data were consistent with a cis arrangement for the dppm ligands and a bidentate coordination through carboxylate oxygens of the quin and kynu anions. These complexes were not able to intercalate CT-DNA as shown by circular dichroism spectroscopy. On the other hand, bovine serum albumin (BSA) binding constants and thermodynamic parameters suggest spontaneous interactions with this protein by hydrogen bonds and van der Waals forces. Cytotoxicity assays were carried out on a panel of human cancer cell lines including HepG2, MCF-7, and MO59J and one normal cell line GM07492A. In general, the new ruthenium(II) complexes displayed a moderate to high cytotoxicity in all the assayed cell lines with IC₅₀ ranging from 10.1 to 36 µM and were more cytotoxic than the precursor cis-[RuCl₂(dppm)₂]. The cis-[Ru(quin)(dppm)₂]PF₆ were two to three times more active than the reference metallodrug cisplatin in the MCF-7 and MO59J cell lines.

Cobalt (II) complex with novel unsymmetrical tetradentate Schiff base (ON) ligand: in vitro cytotoxicity studies of complex, interaction with DNA/protein, molecular docking studies, and antibacterial activity

[C₂₀H₁₇N₃O₂] and cobalt (II) complex [Co(L²)(MeOH)₂].ClO₄, (L² = 4-((E)-1-((2-(((E)-pyridin-2-ylmethylene) amino) phenyl) imino) ethyl) benzene-1, 3-diol) novel Schiff base has been synthesiszed and chracterized by Fourier transform infrared, UV-vis, ¹H-NMR spectroscopy, and elemental analysis techniques. The interaction of Co(II) complex with DNA and BSA was investigated by electronic absorption spectroscopy, fluorescence spectroscopy, circular dichroism, and thermal denaturation studies. Our experiments indicate that this complex could strongly bind to CT-DNA via minor groove mechanism. In addition, fluorescence spectrometry of BSA with the complex showed that the fluorescence quenching mechanism of BSA was of static type. The complex exhibited significant in vitro cytotoxicity against three human cancer cell lines (JURKAT, SKOV3, and U87). The molecular docking experiment effectively proved the binding of complex to DNA and BSA. Finally, antibacterial assay over gram-positive and gram-negative pathogenic bacterial strains was studied.

Therapeutic evolution of benzimidazole derivatives in the last quinquennial period

Benzimidazole, a fused heterocycle bearing benzene and imidazole has gained considerable attention in the field of contemporary medicinal chemistry. The moiety is of substantial importance because of its wide array of pharmacological activities. This nitrogen containing heterocycle is a part of a number of therapeutically used agents. Moreover, a number of patents concerning this moiety in the last few years further highlight its worth. The present review covers the recent work published by scientists across the globe during last five years.

Synthesis, crystal structure and spectroscopic studies of bismuth(III) complex with 2-substituted benzimidazole ligands

Reaction of BiCl3 with 2-(2-hydroxy-3-methoxyphenyl)benzimidazole (HL) in tetrahydrofuran (THF) under reflux gave mononuclear complex of formula [Bi(HL)2Cl3·H2O]. The binding interaction of the complex with bovine serum albumin (BSA) was investigated using the fluorescence quenching method. The experimental results showed that the complex could bind to BSA in the proportion of about 1:1. The binding reaction was spontaneous and hydrophobic force played major role in the reaction. The binding of the complex to BSA could change the microenvironment and conformation of BSA.

Discovery of novel berberine imidazoles as safe antimicrobial agents by down regulating ROS generation

A series of novel berberine-based imidazole derivatives as new type of antimicrobial agents were developed and characterized. Most of them gave good antibacterial activity toward the Gram-positive and negative bacteria. Noticeably, imidazolyl berberine 3a exhibited low MIC value of 1μg/mL against Eberthella typhosa, which was even superior to reference drugs berberine, chloromycin and norfloxacin. The cell toxicity and ROS generation assay indicated that compound 3a showed low cell toxicity. The interactive investigation by UV-vis spectroscopic method revealed that compound 3a could effectively intercalate into calf thymus DNA to form 3a-DNA complex which might further block DNA replication to exert the powerful antimicrobial activities. The binding behavior of compound 3a to DNA topoisomerase IB revealed that hydrogen bonds and electrostatic interactions played important roles in the association of compound 3a with DNA topoisomerase IB.

Recent Development of Benzimidazole-Containing Antibacterial Agents

Clinically significant antibiotic resistance is one of the greatest challenges of the twenty-first century. However, new antibacterial agents are currently being developed at a much slower pace than our growing need for such drugs. Given their diverse biological activities and clinical applications, many bioactive heterocyclic compounds containing a benzimidazole nucleus have been the focus of interest for many researchers. The benzimidazole nucleus is a structural isostere of naturally occurring nucleotides. This advantage allows benzimidazoles to readily interact with the various biopolymers found in living systems. In view of this situation, much attention has been given to the exploration of benzimidazole-based antibacterial agents, leading to the discovery of many new chemical entities with intriguing profiles. In this minireview we summarize novel benzimidazole derivatives active against various bacterial strains. In particular, we outline the relationship between the structures of variously modified benzimidazoles and their antibacterial activity.

Discovery of membrane active benzimidazole quinolones-based topoisomerase inhibitors as potential DNA-binding antimicrobial agents

A series of novel benzimidazole quinolones as potential antimicrobial agents were designed and synthesized. Most of the prepared compounds exhibited good or even stronger antimicrobial activities in comparison with reference drugs. The most potent compound 15m was membrane active and did not trigger the development of resistance in bacteria. It not only inhibited the formation of biofilms but also disrupted the established Staphylococcus aureus and Escherichia coli biofilms. It was able to inhibit the relaxation activity of E. coli topoisomerase IV at 10 μM concentration. Moreover, this compound also showed low toxicity against mammalian cells. Molecular modeling and experimental investigation of compound 15m with DNA suggested that this compound could effectively bind with DNA to form a steady 15m-DNA complex which might further block DNA replication to exert the powerful bioactivities.

Synthesis of novel sulfonamide azoles via C–N cleavage of sulfonamides by azole ring and relational antimicrobial study

Novel sulfonamide azoles were synthesizedviathe C–N cleavage of sulfonamides by an azole ring, and evaluated for their relational antimicrobial behaviors.

Synthesis and biological evaluation of a new class of quinazolinoneazoles as potential antimicrobial agents and their interactions with calf thymus DNA and human serum albumin

A series of quinazolinone azoles were synthesized and screened for their antimicrobial activities, and further studies of their binding behaviors with calf thymus DNA and human serum albumin were investigated.

Design, synthesis, and antibacterial evaluation of novel azolylthioether quinolones as MRSA DNA intercalators

Synthesis of a series of azolylthioether quinolones as a new type of potential antimicrobial agents, and preliminary interactions with MRSA DNA indicated a possible interaction mechanism.

1-[(2E)-3-Phenylprop-2-enoyl]-1H-benzimidazoles as anticancer agents: synthesis, crystal structure analysis and binding studies of the most potent anticancer molecule with serum albumin

The anticancer activity of 1H-benzimidazoles was studied against NCI 60 cell panel. Compound 3f showed antitumor activity with good to moderate selectivity ratio. Mechanism of interaction of 3f with protein was studied by spectral methods.

Synthesis, crystal studies and in vivo anti-hyperlipidemic activities of indole derivatives containing fluvastatin nucleus

As a part of our efforts to prepare better analogues of fluvastatin for the treatment of hyperlipidemia, we have synthesized some indole derivatives containing a fluvastatin nucleus by methanol mediated Claisen–Schmidt aldol condensation reaction.

Synthesis of tetrazole compounds as a novel type of potential antimicrobial agents and their synergistic effects with clinical drugs and interactions with calf thymus DNA

A series of tetrazole derivatives were synthesized and characterized by NMR, IR, MS and HRMS spectroscopy.