Antiviral activity of benzimidazole derivatives. III. Novel anti-CVB-5, anti-RSV and anti-Sb-1 agents

Innovative Arylimidazole-Fused Phytovirucides via Carbene-Catalyzed [3+4] Cycloaddition: Locking Viral Cell-To-Cell Movement by Out-Competing Virus Capsid-Host Interactions

The control of potato virus Y (PVY) induced crop failure is a challengeable issue in agricultural chemistry. Although many anti-PVY agents are designed to focus on the functionally important coat protein (CP) of virus, how these drugs act on CP to inactivate viral pathogenicity, remains largely unknown. Herein, a PVY CP inhibitor -3j (S) is disclosed, which is accessed by developing unusually efficient (up to 99% yield) and chemo-selective (> 99:1 er in most cases) carbene-catalyzed [3+4] cycloaddition reactions. Compound -3j bears a unique arylimidazole-fused diazepine skeleton and shows chirality-preferred performance against PVY. In addition, -3j (S) as a mediator allows ARG191 (R191) of CP to be identified as a key amino acid site responsible for intercellular movement of virions. R191 is further demonstrated to be critical for the interaction between PVY CP and the plant functional protein NtCPIP, enabling virions to cross plasmodesmata. This key step can be significantly inhibited through bonding with the -3j (S) to further impair pathogenic behaviors involving systemic infection and particle assembly. The study reveals the in-depth mechanism of action of antiviral agents targeting PVY CP, and contributes to new drug structures and synthetic strategies for PVY management.

Design, synthesis, and anti-respiratory syncytial virus potential of novel 3-(1,2,3-triazol-1-yl)furoxazine-fused benzimidazole derivatives

Respiratory syncytial virus (RSV) is a major cause of serious lower respiratory tract infections in infants, children, and older persons. Currently, the only approved anti-viral chemotherapeutic drug for RSV treatment is ribavirin aerosol; however, its significant toxicity has led to restricted clinical use. In a previous study, we developed various benzimidazole derivatives against RSV. In this study, we synthesised 3-azide substituted furoxazine-fused benzimidazole derivatives by sulfonylation and azide substitution of the 3-hydroxyl group of the furoxazine-fused benzimidazole derivatives. Subsequently, a series of 3-(1,2,3-triazol-1-yl)-substituted furoxazine-fused benzimidazole derivatives were synthesised using the classical click reaction. Biological evaluations of the target compounds indicated that compound 4a-2 had higher activity against RSV (EC50 = 12.17 μM) and lower cytotoxicity (CC50 = 390.64 μM). Compound 4a-2 exerted anti-viral effects against the RSV Long strain by inhibiting apoptosis and the elevation of reactive oxygen species (ROS) and inflammatory factors caused by viral infection in vitro. Additionally, the clinical symptoms of the virus-infected mice were markedly relieved, and the viral load in the lung tissues was dramatically decreased. The biosafety profile of compound 4a-2 was also favourable, showing no detectable adverse effects on any of the major organs in vivo. These findings underscore the potential of compound 4a-2 as a valuable therapeutic option for combating RSV infections while also laying the foundation for further research and development in the field.

Virtual Screening of Benzimidazole Derivatives as Potential Triose Phosphate Isomerase Inhibitors with Biological Activity against Leishmania mexicana

Leishmania mexicana (L. mexicana) is a causal agent of cutaneous leishmaniasis (CL), a “Neglected disease”, for which the search for new drugs is a priority. Benzimidazole is a scaffold used to develop antiparasitic drugs; therefore, it is interesting molecule against L. mexicana. In this work, a ligand-based virtual screening (LBVS) of the ZINC15 database was performed. Subsequently, molecular docking was used to predict the compounds with potential binding at the dimer interface of triosephosphate isomerase (TIM) of L. mexicana (LmTIM). Compounds were selected on binding patterns, cost, and commercial availability for in vitro assays against L. mexicana blood promastigotes. The compounds were analyzed by molecular dynamics simulation on LmTIM and its homologous human TIM. Finally, the physicochemical and pharmacokinetic properties were determined in silico. A total of 175 molecules with docking scores between −10.8 and −9.0 Kcal/mol were obtained. Compound E2 showed the best leishmanicidal activity (IC50 = 4.04 µM) with a value similar to the reference drug pentamidine (IC50 = 2.23 µM). Molecular dynamics analysis predicted low affinity for human TIM. Furthermore, the pharmacokinetic and toxicological properties of the compounds were suitable for developing new leishmanicidal agents.

Benzimidazole-2-Phenyl-Carboxamides as Dual-Target Inhibitors of BVDV Entry and Replication

Bovine viral diarrhea virus (BVDV), also known as Pestivirus A, causes severe infection mostly in cattle, but also in pigs, sheep and goats, causing huge economical losses on agricultural farms every year. The infections are actually controlled by isolation of persistently infected animals and vaccination, but no antivirals are currently available to control the spread of BVDV on farms. BVDV binds the host cell using envelope protein E2, which has only recently been targeted in the research of a potent and efficient antiviral. In contrast, RdRp has been successfully inhibited by several classes of compounds in the last few decades. As a part of an enduring antiviral research agenda, we designed a new series of derivatives that emerged from an isosteric substitution of the main scaffold in previously reported anti-BVDV compounds. Here, the new compounds were characterized and tested, where several turned out to be potent and selectively active against BVDV. The mechanism of action was thoroughly studied using a time-of-drug-addition assay and the results were validated using docking simulations.

Probing In Silico the Benzimidazole Privileged Scaffold for the Development of Drug-like Anti-RSV Agents

Targeting the fusion (F) protein has been recognized as a fruitful strategy for the development of anti-RSV agents. Despite the considerable efforts so far put into the development of RSV F protein inhibitors, the discovery of adequate therapeutics for the treatment of RSV infections is still awaiting a positive breakthrough. Several benzimidazole-containing derivatives have been discovered and evaluated in clinical trials, with only some of them being endowed with a promising pharmacokinetic profile. In this context, we applied a computational study based on a careful analysis of a number of X-ray crystallographic data of the RSV F protein, in the presence of different clinical candidates. A deepen comparison of the related electrostatic features and H-bonding motifs allowed us to pave the way for the following molecular dynamic simulation of JNJ-53718678 and then to perform docking studies of the in-house library of potent benzimidazole-containing anti-RSV agents. The results revealed not only the deep flexibility of the biological target but also the most relevant and recurring key contacts supporting the benzimidazole F protein inhibitor ability. Among them, several hydrophobic interactions and π-π stacking involving F140 and F488 proved to be mandatory, as well as H-bonding to D486. Specific requirements turning in RSV F protein binding ability were also explored thanks to structure-based pharmacophore analysis. Along with this, in silico prediction of absorption, distribution, metabolism, excretion (ADME) properties, and also of possible off-target events was performed. The results highlighted once more that the benzimidazole ring represents a privileged scaffold whose properties deserve to be further investigated for the rational design of novel and orally bioavailable anti-RSV agents.

Exploration of potential inhibitors for tuberculosis via structure-based drug design, molecular docking, and molecular dynamics simulation studies

Drug resistance in tuberculosis is major threat to human population. In the present investigation, we aimed to identify novel and potent benzimidazole molecules to overcome the resistance management. A series of 20 benzimidazole derivatives were examined for its activity as selective antitubercular agents. Initially, AutodockVina algorithm was performed to assess the efficacy of the molecules. The results are further enriched by redocking by means of Glide algorithm. The binding free energies of the compounds were then calculated by MM-generalized-born surface area method. Molecular docking studies elucidated that benzimidazole derivatives has revealed formation of hydrogen bond and strong binding affinity in the active site of Mycobacterium tuberculosis protein. Note that ARG308, GLY189, VAL312, LEU403, and LEU190 amino acid residues of Mycobacterium tuberculosis protein PrpR are involved in binding with ligands of benzimidazoles. Interestingly, the ligands exhibited same binding potential to the active site of protein complex PrpR in both the docking programs. In essence, the result portrays that benzimidazole derivatives such as 1p, 1q, and 1 t could be potent and selective antitubercular agents than the standard drug isoniazid. These compounds were then subjected to molecular dynamics simulation to validate the dynamics activity of the compounds against PrpR. Finally, the inhibitory behavior of compounds was predicted using a machine learning algorithm trained on a data collection of 15,000 compounds utilizing graph-based signatures. Overall, the study concludes that designed benzimidazoles can be employed as antitubercular agents. Indeed, the results are helpful for the experimental biologists to develop safe and non-toxic drugs against tuberculosis.

Synthesis and fungicidal activity of novel 2-(2-alkylthio-6-phenylpyrimidin-4-yl)-1H-benzimidazoles

With the aim of exploring new benzimidazole derivative with high fungicidal activity, a series of novel 2-(2-(alkylthio)-6-phenylpyrimidin-4-yl)-1H-benzimidazoles were designed and synthesized, and their in vitro fungicidal activities were evaluated. Compounds 5a, 5f, 5g, 5h, 5i and 5l exhibited excellent fungicidal activities against Botrytis cinerea, and 5c, 5f, 5h, 5i and 5l displayed notable fungicidal activities against Sclerotinia sclerotiorum. Among them, compound 5i (R¹ = fluorine, R² = benzyl) displayed the best activity towards the two tested fungi. Docking study of 5i with β-tubulin protein revealed that the NH moiety of benzimidazole ring generated a hydrogen bond with Gln-11 residue, and the fluorine atom of benzene ring formed a hydrogen bond with Tyr-208 residue, respectively; the benzene ring of Tyr-222 and the pyrimidine ring of 5i yielded a π-π interaction. The molecular electrostatic potential analysis elucidated the nitrogen atom of benzimidazole ring, fluorine atom of benzene ring and sulfur atom of thioether moiety were located in the negative potential regions, whereas some hydrogen atoms of benzene, benzimidazole and pyrimidine rings were located in the positive potential regions. This analysis demonstrated the reason why 5i can form hydrogen bonds with amino acid residues of target protein.

Astemizole as a drug to inhibit the effect of SARS-COV-2 in vitro

Since the beginning of December 2019, a novel Coronavirus severe respiratory disease, caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) which also been termed 2019-new CoV (2019-nCoV), has continued to spread worldwide. As of August 27, 2020, a total of 24,232,429 people have been infected and 826,518 people have died. In our study, we found that astemizole can antagonize ACE2 and inhibit the entry of SARS-COV-2 spike pseudovirus into ACE2-expressed HEK293T cells (ACE2hi cells). We analysied the binding character of astemizole to ACE2 by molecular docking and surface plasmon resonance (SPR) assays and molecule docking, SARS-COV-2 spike pseudotype virus was also taken to investigate the suppression viropexis effect of astemizole. The results showed that astemizole can bind to the ACE2 receptor and inhibit the invasion of SARS-COV-2 Spike pseudoviruses. Thus astemizole represent potential drug candidates that can be re-used in anti-coronavirus therapies.

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.

Preparation of 1,2-substituted benzimidazoles via a copper-catalyzed three component coupling reaction

1,2-Substituted benzimidazoles were prepared by simply stirring a mixture of copper catalysts, N-substituted o-phenylenediamines, sulfonyl azides and terminal alkynes. Particularly, the intermediate N-sulfonylketenimine occurred with two nucleophilic addition and the sulfonyl group was eliminated via cyclization. In a way, sulfonyl azides and copper catalysts activated the terminal alkynes to synthesize benzimidazoles.

Synthesis of purines and adenines containing the hexafluoroisopropyl group

Several new derivatives of adenine, purine, and theophylline containing the (CF₃)₂CH group connected to a nitrogen atom of the imidazole ring were prepared by the reaction of 2,2,4,4-tetrakis(trifluoromethyl)-1,3-dithietane (1) with the corresponding substrates, resulting in the selective alkylation of one of the nitrogen atoms of the imidazole ring. The reaction proceeds under mild conditions in a polar solvent, giving the alkylated products in 47–78% yield. While for purine and 4- and 5-azabenzimidazole, the reaction led to a mixture of two isomers, the reaction of adenine and the corresponding 2-fluoro derivative was regioselective, resulting in the formation of only one isomer in each case. The alkylation of theophylline led to the formation of a new derivative of caffeine.

Importance of Fluorine in Benzazole Compounds

Fluorine-containing heterocycles continue to receive considerable attention due to their unique properties. In medicinal chemistry, the incorporation of fluorine in small molecules imparts a significant enhancement their biological activities compared to non-fluorinated molecules. In this short review, we will highlight the importance of incorporating fluorine as a basic appendage in benzothiazole and benzimidazole skeletons. The chemistry and pharmacological activities of heterocycles containing fluorine during the past years are compiled and discussed.

Synthesis, bioevaluation and docking studies of some 2-phenyl-1H-benzimidazole derivatives as anthelminthic agents against the nematode Teladorsagia circumcincta

Gastrointestinal nematode infections are the main diseases in herds of small ruminants. Resistance to the main established drugs has become a worldwide problem. The purpose of this study is to obtain and evaluate the in vitro ovicidal and larvicidal activity of some 2-phenylbenzimidazole derivatives on susceptible and resistant strains of Teladorsagia circumcincta. Compounds were prepared by known procedures from substituted o-phenylenediamines and arylaldehydes or intermediate sodium 1-hydroxyphenylmethanesulfonate derivatives. Egg Hatch Test (EHT), Larval Mortality Test (LMT) and Larval Migration Inhibition Test (LMIT) were used in the initial screening of compounds at 50 μM concentration, and EC₅₀ values were determined for the most potent compounds. Cytotoxicity evaluation of compounds was conducted on human Caco-2 and HepG2 cell lines to calculate their Selectivity Indexes (SI). At 50 μM concentration, nine out of twenty-four compounds displayed more than 98% ovicidal activity on a susceptible strain, and four of them showed more than 86% on one resistant strain. The most potent ovicidal benzimidazole (BZ) 3 showed EC₅₀ = 6.30 μM, for the susceptible strain, while BZ 2 showed the lowest EC₅₀ value of 14.5 μM for the resistant strain. Docking studies of most potent compounds in a modelled Teladorsagia tubulin indicated an inverted orientation for BZ 1 in the colchicine binding site, probably due to its fair interaction with glutamic acid at codon 198, which could justify its inactivity against the resistant strain of T. circumcincta.

Design, synthesis, mechanistic studies and in silico ADME predictions of benzimidazole derivatives as novel antifungal agents

Herein, novel three series of benzimidazole scaffold bearing hydrazone, 1,2,4-triazole and 1,3,4-oxadiazole moieties 1-3, 4a-j, 6a-c and 7 derivatives were designed, synthesized and evaluated for their antimicrobial activity. The structures of the prepared compounds were assigned using different spectroscopic techniques such as IR, ¹H NMR, ¹³C NMR and elemental analyses. Compounds 3, 4a, 4e and 4f exhibited remarkable antifungal activity against C. albicans and C. neoformans var. grubii with MIC values ranging from 4 to 16 μg/mL. Furthermore, they were not cytotoxic against red blood cells and human embryonic kidney cells at concentration up to 32 μg/mL. The study was expanded to forecast the mechanism of action of the prepared compounds and determine sterol quantitation method (SQM) by spectrophotometric assay. On the other hand, compound 4e showed the highest inhibitory activity against lanosterol 14α-demethylase (CYP51) with IC₅₀ value = 0.19 μg/mL compared to fluconazole as reference IC₅₀ value = 0.62 μg/mL. Also, compounds 4d and 4f exhibited mild to moderate antibacterial activity. Moreover, molecular docking of the active target compound 4e in active site of lanosterol 14α-demethylase (CYP51) revealed that docking scores and binding mode are comparable to that of co-crystallized ligand confirming their antifungal activity. In silico ADME prediction investigations also forecasting the drug-like characters of these compounds.

Thiol substrate-promoted dehydrogenative cyclization of arylmethyl thiols with ortho-substituted amines: a universal approach to heteroaromatic compounds

A thiol substrate-promoted one-pot synthesis of a library of heteroaromatic compounds was developed.

An Expedient Synthesis of CMF-019: (S)-5-Methyl-3-{1-(pentan-3-yl)-2- (thiophen-2-ylmethyl)-1H-benzo[d]imidazole-5-carboxamido}hexanoic Acid, a Potent Apelin Receptor (APJ) Agonist

BACKGROUND

Apelin receptor (APJ) is a G protein-coupled receptor (GPCR) activated by the endogenous peptide apelin. The apelin-APJ system has emerged as an important regulator of cardiovascular homeostasis. Recently, a potent benzimidazole-derived apelin peptidomimetic, CMF-019, was patented but without a comprehensive description of its synthesis and a complete spectroscopic characterization of the intermediates.

OBJECTIVE

Here, a detailed preparation of CMF-019 through a modified and improved synthetic pathway is described.

METHOD

In particular, the benzimidazole ring in 7 was tailored by the condensation of methyl 3- amino-4-(pentan-3-ylamino)benzoate (4) with (thiophene-2-yl)acetimidate salt 6. Saponification of 7 and the subsequent condensation of the free acid 8 with the corresponding enantiopure β-amino acid methyl ester generated methyl (S)-5-methyl-3-{1-(pentan-3-yl)-2-(thiophen-2-ylmethyl)-1Hbenzo[ d]imidazole-5-carboxamido}hexanoate (9). Hydrolysis of the latter with KOH in THF/water, followed by HPLC-purification, afforded the desired product, CMF-019 (potassium salt) 10.

RESULTS & CONCLUSION

The approach reported herein enables preparation of 10 at a total yield of 12% over seven linear steps. Additionally, it does not require applying expensive designated microwave reactors and high-pressure hydrogenators. Thus, the elaborate synthesis provides a latent availability of potent agonist 10 for further exploring the physiologically essential apelin-APJ system.

Exploring the effectiveness of novel benzimidazoles as CB2 ligands: synthesis, biological evaluation, molecular docking studies and ADMET prediction

Herein we continued our previous work on the development of CB2 ligands, reporting the design and synthesis of a series of benzimidazole-containing derivatives that were explored as selective CB2 ligands with binding affinity towards both CB1 and CB2 receptors. Seven out of eighteen compounds exhibited preferential binding ability to CB2 over CB1 receptors with potencies in the sub-micromolar or low micromolar range. In particular, we identified two promising hit compounds, the agonist 1-[2-(N,N-diethylamino)ethyl]-2-(4-ethoxybenzyl)-5-trifluoromethylbenzimidazole (3) (CB2: K _i = 0.42 μM) and the inverse agonist/antagonist 1-butyl-2-(3,4-dichlorobenzyl)-5-trifluoromethylbenzimidazole (11) (CB2: K _i = 0.37 μM). Docking studies also performed on other benzimidazoles reported in the literature supported the structure-activity relationship observed in this series of compounds and allowed the key contacts involved in the agonist and/or inverse agonist behaviour displayed by these derivatives to be determined. The in silico evaluation of ADMET properties suggested a favorable pharmacokinetic and safety profile, promoting the drug-likeness of these compounds towards a further optimization process.

Synthesis of New Fluoro-Benzimidazole Derivatives as an Approach towards the Discovery of Novel Intestinal Antiseptic Drug Candidates

In the present study, nineteen new fluoro-benzimidazole derivatives, including nifuroxazide analogs, were synthesized by microwave-supported reactions and tested against a panel of pathogenic microorganisms consisting of resistant strains. The synthesized compounds were characterized and identified by FT-IR, 1H- and 13C-NMR, mass spectroscopy, and elemental analyses, respectively. In vitro antimicrobial and cytotoxic effects of the synthesized compounds were determined by microdilution and by [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (MTT) assay. The compound 4-[5(6)-fluoro-1H-benzimidazol-2-yl)-N'-(2-methylbenzylidene)]benzohydrazide (18) showed particularly high inhibitory activity against the gastro-intestinal pathogens, such as Escherichia coli O157:H7, Escherichiacoli ATCC 8739, Escherichia coli ATCC 35218 and Salmonella typhimurium ATCC 13311 standard strains, with minimum inhibitory concentrations (MIC90) ranging from 0.49–0.98 µg/mL. The microbial panel contained a total of ten pathogens including Klebsiella sp., Mycobacterium sp., MRSA, etc., for which the level of inhibitory activity measured was higher than that exhibited by the tested concentrations (MIC > 1000 µg/mL). In vitro cytotoxicity results revealed that the inhibitory concentration (IC50) value (210.23 µg/mL) of compound 18 against CCD 841 CoN cells (human intestinal epithelial cell line) is about 430 times higher than its MIC90 value against the tested Escherichia coli strains. Furthermore, the docking study of compound 18 suggested that its structure is very compatible with the active site pocket of the phosphofructokinase-2 enzyme.

Synthesis, Characterization, and Antifungal Activity of Novel Benzo[4,5]imidazo[1,2-d][1,2,4]triazine Derivatives

A series of novel fused heterocyclic compounds bearing benzo[4,5]imidazo[1,2-d][1,2,4]triazine 4a–4w were designed and conveniently synthesized via the intermediates 2-(halogenated alkyl)-1H-benzo[d]imidazoles 2a, 2b, and 2-((1-(substituted phenyl)hydrazinyl)alkyl)-1H-benzo[d]imidazoles 3a–3g. The structures of all target compounds were characterized by FT-IR, ¹H NMR, ¹³C NMR, and EI-MS, of which, the structure of compound 4n was further determined by the single crystal X-ray diffraction. The crystal structure of 4n was crystallized in the triclinic crystal system, space group P1¯ with a = 9.033 (6) Å, b = 10.136 (7) Å, c = 10.396 (7) Å, α = 118.323 (7)°, β = 91.750 (8)°, γ = 104.198 (7)°, Z = 2, V = 800.2 (9) ų; total R indices: R₁ = 0.0475, wR₂ = 0.1284. The antifungal activity of title compounds 4a–4w in vitro against the phytopathogenic fungi Botrytis cinerea (B. cinerea), Rhizoctonia solani (R. solani) and Colletotrichum capsici (C. capsici) were evaluated, the bioassay results demonstrated that most of the title compounds exhibited obvious fungicidal activities at 50 μg/mL. This work indicated that benzo[4,5]imidazo[1,2-d][1,2,4]triazine derivatives could be considered as a new leading structure in searching for novel agricultural fungicides.

Host dihydrofolate reductase (DHFR)-directed cycloguanil analogues endowed with activity against influenza virus and respiratory syncytial virus

We have identified a series of 1-aryl-4,6-diamino-1,2-dihydrotriazines, structurally related to the antimalarial drug cycloguanil, as new inhibitors of influenza A and B virus and respiratory syncytial virus (RSV) via targeting of the host dihydrofolate reductase (DHFR) enzyme. Most analogues proved active against influenza B virus in the low micromolar range, and the best compounds (11, 13, 14 and 16) even reached the sub-micromolar potency of zanamivir (EC50 = 0.060 μM), and markedly exceeded (up to 327 times) the antiviral efficacy of ribavirin. Activity was also observed for two influenza A strains, including a virus with the S31N mutant form of M2 proton channel, which is the most prevalent resistance mutation for amantadine. Importantly, the compounds displayed nanomolar activity against RSV and a superior selectivity index, since the ratio of cytotoxic to antiviral concentration was >10,000 for the three most active compounds 11, 14 and 16 (EC50 ∼0.008 μM), far surpassing the potency and safety profile of the licensed drug ribavirin (EC50 = 5.8 μM, SI > 43).

New Benzimidazole-1,2,4-Triazole Hybrid Compounds: Synthesis, Anticandidal Activity and Cytotoxicity Evaluation

Owing to the growing need for antifungal agents, we synthesized a new series 2-((5-(4-(5-substituted-1H-benzimidazol-2-yl)phenyl)-4-substituted-4H-1,2,4-triazol-3-yl)thio)-1-(substitutedphenyl)ethan-1-one derivatives, which were tested against Candida species. The synthesized compounds were characterized and elucidated by FT-IR, ¹H-NMR, ¹³C-NMR and HR-MS spectroscopies. The synthesized compounds were screened in vitro anticandidal activity against Candida species by broth microdiluation methods. In vitro cytotoxic effects of the final compounds were determined by MTT assay. Microbiological studies revealed that compounds 5m, 5o, 5r, 5t, 5y, 5ab, and 5ad possess a good antifungal profile. Compounds 5w was the most active derivative and showed comparable antifungal activity to those of reference drugs ketoconazole and fluconazole. Cytotoxicity evaluation of compounds 5m, 5o, 5r, 5w, 5y, 5ab and 5ad showed that compounds 5w and 5ad were the least cytotoxic agents. Effects of these two compounds against ergosterol biosynthesis were observed by LC-MS-MS method, which is based on quantification of ergosterol level in C. albicans. Compounds 5w and 5d inhibited ergosterol biosynthesis concentration dependently. A fluorescence microscopy study was performed to visualize effect of compound 5w against C. albicans at cellular level. It was determined that compound 5w has a membrane damaging effect, which may be related with inhibition of biosynthesis of ergosterol.

Benzimidazole-based derivatives as privileged scaffold developed for the treatment of the RSV infection: a computational study exploring the potency and cytotoxicity profiles

Respiratory syncytial virus (RSV) has been identified as a main cause of hospitalisation in infants and children. To date, the current therapeutic arsenal is limited to ribavirin and palivizumab with variable efficacy. In this work, starting from a number of in-house series of previously described anti-RSV agents based on the benzimidazole scaffold, with the aim at gaining a better understanding of the related chemical features involved in potency and safety profiles, we applied a computational study including two focussed comparative molecular fields analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA). The results allowed us to derive useful suggestions for the design of derivatives and also to set up statistical models predicting the potency and selectivity index (SI = CC₅₀/EC₅₀) of any new analogue prior to synthesis. Accordingly, here, we discuss preliminary results obtained through the applied exhaustive QSAR analyses, leading to design and synthesise more effective anti-RSV agents.

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.

Antiviral activity of polysaccharide extract from Laminaria japonica against respiratory syncytial virus

This study was designed to investigate the inhibition activity of polysaccharide extract from Laminaria japonica against RSV. The polysaccharide from Laminaria japonica was isolated by ethanol precipitation. HEK293 cells were infected with RVS, and the antiviral activity of polysaccharide extract against RSV in host cells was tested. By using ELISA and western blot assay, the expression level of IFN-α and IRF3 and their functional roles in polysaccharide-mediated antiviral activity against RSV were investigated. The polysaccharide extract from Laminaria japonica had low toxicity to HEK293 cell. The TC50 to HEK293 cells was up to 1.76mg/mL. Furthermore, the EC50 of polysaccharide extract to RSV was 5.27μg/mL, and TI was 334. The polysaccharide extract improved IRF-3 expression which promoted the level of IFN-α.

IN CONCLUSION

Polysaccharide extract from Laminaria japonica elicits antiviral activity against RSV by up-regulation of IRF3 signaling-mediated IFN-α production.

Identification of an indol-based derivative as potent and selective varicella zoster virus (VZV) inhibitor

We report the synthesis and antiviral activity of a new family of non-nucleoside antivirals, derived from the indole nucleus. Modifications of this template through Mannich and Friedel-Crafts reactions, coupled with nucleophilic displacement and reductive aminations led to 23 final derivatives, which were pharmacologically tested. Tryptamine derivative 17a was found to have a selective inhibitory activity against human varicella zoster virus (VZV) replication in vitro, being inactive against a variety of other DNA and RNA viruses. A structure-activity relationship (SAR) study showed that the presence of a biphenyl ethyl moiety and the acetylation at the amino group of tryptamine are a prerequisite for anti-VZV activity. The novel compound shows the same activity against thymidine kinase (TK)-competent (TK⁺) and TK-deficient (TK⁻) VZV strains, pointing to a novel mechanism of antiviral action.

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A library of indole-based derivatives has been designed and synthesized as potential antiviral agents.

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Friedel-Crafts and Mannich reactions were used for the synthesis of different indole derivatives.

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Tryptamine derivative 17a displays significant inhibitory activity against VZV replication.

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A mechanism of action independent from the virus-encoded thymidine kinase is suggested.

Computational Study Exploring the Interaction Mechanism of Benzimidazole Derivatives as Potent Cattle Bovine Viral Diarrhea Virus Inhibitors

Bovine viral diarrhea virus (BVDV) infections are prevailing in cattle populations on a worldwide scale. The BVDV RNA-dependent RNA polymerase (RdRp), as a promising target for new anti-BVDV drug development, has attracted increasing attention. To explore the interaction mechanism of 65 benzimidazole scaffold-based derivatives as BVDV inhibitors, presently, a computational study was performed based on a combination of 3D-QSAR, molecular docking, and molecular dynamics (MD) simulations. The resultant optimum CoMFA and CoMSIA models present proper reliabilities and strong predictive abilities (with Q(2) = 0. 64, R(2)ncv = 0.93, R(2)pred = 0.80 and Q(2) = 0. 65, R(2)ncv = 0.98, R(2)pred = 0.86, respectively). In addition, there was good concordance between these models, molecular docking, and MD results. Moreover, the MM-PBSA energy analysis reveals that the major driving force for ligand binding is the polar solvation contribution term. Hopefully, these models and the obtained findings could offer better understanding of the interaction mechanism of BVDV inhibitors as well as benefit the new discovery of more potent BVDV inhibitors.

Inhibition of Chikungunya Virus Replication by 1-[(2-Methylbenzimidazol-1-yl) Methyl]-2-Oxo-Indolin-3-ylidene] Amino] Thiourea(MBZM-N-IBT)

Chikungunya virus (CHIKV) infection is one of the most challenging human Arboviral infections with global significance and without any specific antiviral. In this investigation, 1-[(2-methylbenzimidazol-1-yl) methyl]-2-oxo-indolin-3-ylidene] amino] thiourea (MBZM-N-IBT) was synthesised as a molecular hybrid of 2-methyl benzimidazole and isatin-β-thiosemicarbazone and its anti-CHIKV property was evaluated. The release of infectious virus particles was calculated by plaque assay, expression profile of viral RNA was estimated by RT-PCR and viral protein profiles were assessed by Western blot and FACS analyses. The safety index of MBZM-N-IBT was found to be >21. The CHIKV infectious viral particle formation was abrogated around 76.02% by MBZM-N-IBT during infection in mammalian system and the viral RNA synthesis was reduced by 65.53% and 23.71% for nsP2 and E1 respectively. Surprisingly, the viral protein levels were reduced by 97% for both nsP2 and E2. In the time-of-addition experiment it abrogated viral infection at early as well as late phase of viral life cycle, which indicates about multiple mechanisms for its anti-CHIKV action. In silico analysis justified development of MBZM-N-IBT with good affinities for potential target proteins of CHIKV and related virus. With predictions of good drug-likeness property, it shows potential of a drug candidate which needs further experimental validation.

Antiviral activity of benzotriazole derivatives. 5-[4-(Benzotriazol-2-yl)phenoxy]-2,2-dimethylpentanoic acids potently and selectively inhibit Coxsackie Virus B5

A library of 64 benzotriazole derivatives (17 of which were [4-(benzotriazol-2-yl)phenoxy]alkanoic acids) were screened for antiviral activity against a panel of twelve DNA and RNA viruses. Twenty-six compounds (12 of which were [4-(benzotriazol-2-yl)phenoxy]alkanoic acids) displayed activity against one or more viruses. CVB-5, RSV, BVDV, Sb-1 and YFV were, in decreasing order, the more frequently and effectively affected viruses; DENV-2, WNV, HIV-1 and Reo-1 were only occasionally and modestly affected, while the remaining viruses were not affected by any of the tested compounds. Worth of note were compounds 33 and 35; the former for the activity against Sb-1 (EC50=7 μM) and the latter for the large spectrum of activity including six viruses with a mean EC50=12 μM. Even more interesting were the alkanoic acids 45-48 and 50-57 for their activity against RSV and/or CVB-5. In particular, compound 56 displayed a potent and selective activity against CVB-5 with EC50=0.15 μM and SI=100, thus representing a valuable hit compound for the development of antiviral agents for the treatment of human pathologies related to this virus.

Synthesis and Evaluation of Selected Benzimidazole Derivatives as Potential Antimicrobial Agents

A library of 53 benzimidazole derivatives, with substituents at positions 1, 2 and 5, were synthesized and screened against a series of reference strains of bacteria and fungi of medical relevance. The SAR analyses of the most promising results showed that the antimicrobial activity of the compounds depended on the substituents attached to the bicyclic heterocycle. In particular, some compounds displayed antibacterial activity against two methicillin-resistant Staphylococcus aureus (MRSA) strains with minimum inhibitory concentrations (MICs) comparable to the widely-used drug ciprofloxacin. The compounds have some common features; three possess 5-halo substituents; two are derivatives of (S)-2-ethanaminebenzimidazole; and the others are derivatives of one 2-(chloromethyl)-1H-benzo[d]imidazole and (1H-benzo[d]imidazol-2-yl)methanethiol. The results from the antifungal screening were also very interesting: 23 compounds exhibited potent fungicidal activity against the selected fungal strains. They displayed equivalent or greater potency in their MIC values than amphotericin B. The 5-halobenzimidazole derivatives could be considered promising broad-spectrum antimicrobial candidates that deserve further study for potential therapeutic applications.