Synthesis, antimycobacterial, antiviral, antimicrobial activities, and QSAR studies of nicotinic acid benzylidene hydrazide derivatives

Pd-, Cu-, and Ni-Catalyzed Reactions: A Comprehensive Review of the Efficient Approaches towards the Synthesis of Antibacterial Molecules

A strong synthetic tool for many naturally occurring chemicals, polymers, and pharmaceutical substances is transition metal-catalyzed synthesis. A serious concern to human health is the emergence of bacterial resistance to a broad spectrum of antibacterial medications. The synthesis of chemical molecules that are potential antibacterial candidates is underway. The main contributions to medicine are found to be effective in transition metal catalysis and heterocyclic chemistry. This review underlines the use of heterocycles and certain effective transition metals (Pd, Cu, and Ni) as catalysts in chemical methods for the synthesis of antibacterial compounds. Pharmaceutical chemists might opt for clinical exploration of these techniques due to their potential.

Synthesis, Anti-Bacterial and Molecular Docking Studies of Arylated Butyl 2-Bromoisonicotinate Against Clinical Isolates of ESBL-Producing Escherichia coli ST405 and Methicillin-Resistant Staphylococcus aureus

Introduction

Global public health concerns include the emergence and spread of methicillin-resistant Staphylococcus aureus (MRSA) and extended-spectrum beta-lactamase Escherichia coli (ESBL-E. coli). These pathogens cause infections that are difficult to treat, which can have fatal outcomes and require lengthy hospital stays. As a result, we created butyl 2-bromoisonicotinate and tested its antibacterial effectiveness against the ESBL-E. coli ST 405 and MRSA pathogens. Natural product discovery is complemented by synthetic compound synthesis because of the latter's potential for superior characteristics, target specificity, scalability, intellectual advantages, and chemical diversity. Because of this, the potential for discovering new medicinal compounds is increased, and the constraints placed on natural sources are overcome. Natural items are tough to obtain since they are hard to isolate and synthesize. Therefore, modern science is actively searching for small molecules as therapeutic agents by applying sustainable techniques that can be commercialized.

Methods

Two patients' blood samples were taken, and the BACTEC/Alert system was used to process them. On blood and MacConkey agar, the positive samples were subcultured and incubated aerobically at 37 °C. Using the VITEK 2 compact system, the isolates were subjected to isolate identification and MIC. MLST of the ESBL-E. coli was performed by PCR. Additionally, Fischer esterification was used to create butyl 2-bromoisonicotinate in excellent yields. A commercially available palladium catalyst was then used to arylate the compound, resulting in medium to good yields of arylated butyl 2-bromoisonicotinates. Using the agar well diffusion assay and the micro-broth dilution method, we assessed the in-vitro activities of the synthesized molecules (3, 5a-h) against clinically isolated ESBL-E. coli ST405, and MRSA. A molecular operating environment was used to carry out in silico validation of the synthesized compounds' binding to the active site and to evaluate the stability of their molecular interactions with the target E. coli 2Y2T protein.

Results

MRSA and ESBL-producing E. coli were identified as the two clinical isolates. While MRSA was also resistant to beta-lactam drugs and least resistant to vancomycin, ESBL-producing E. coli belonged to ST405 and was resistant to cephalosporins and sensitive to carbapenems. Good yields of the desired compounds were produced by our effective and economical synthesis. By using a micro-broth dilution assay, the Molecules (3, 5a, and 5d) were most effective against both resistant strains. The Molecules (3, 5a, 5b, and 5d) also displayed good binding energies.

Conclusion

The butyl 2-bromoisonicotinate displayed antibacterial efficacy against ESBL-producing E. coli ST405 and MRSA strains. After the in-vivo trial, this substance might offer an alternative therapeutic option.

Design, synthesis and biological evaluation of novel oxindole analogs as antitubercular agents

Aim: To design, synthesize and evaluate oxindole derivatives for antitubercular activity. Methodology: We synthesized the derivatives, confirmed their structures by 1H/13C NMR and mass spectrometry, and evaluated them for antitubercular activity against Mycobacterium tuberculosis H37Rv strain using the microplate alamarBlue™ assay. Results: Among all the synthesized derivatives, OXN-1, -3 and -7 exhibited excellent antitubercular activity (minimum inhibitory concentration [MIC]: 0.78 μg/ml). Compounds with a MIC ≤1.56 were tested for cytotoxicity against human embryonic kidney cells and were found to be relatively nontoxic. Molecular docking analysis of OXN-1, -3 and -7 was performed to determine their binding patterns at the active site of DNA topoisomerase II (PDB-5BS8). In drug combination studies, OXN-1, 3 and 7 showed synergism with isoniazid. Conclusion: The obtained results reveal that oxindole derivatives exhibit potent antitubercular activity.

Recent advances on dual inhibitors targeting HIV reverse transcriptase associated polymerase and ribonuclease H

Reverse transcriptase (RT) plays an indispensable role in the replication of human immunodeficiency virus (HIV) through its associated polymerase and ribonuclease H (RNase H) activities during the viral RNA genome transformation into proviral DNA. Due to the fact that HIV is a highly mutagenic virus and easily resistant to single-target RT inhibitors, dual inhibitors targeting HIV RT associated polymerase and RNase H have been developed. These dual inhibitors have the advantages of increasing efficacy, reducing drug resistance, drug-drug interactions, and cytotoxicity, as well as improving patient compliance. In this review, we summarize recent advances in polymerase/RNase H dual inhibitors focusing on drug design strategies, and structure-activity relationships and share new insights into developing anti-HIV drugs.

Current medicinal chemistry strategies in the discovery of novel HIV-1 ribonuclease H inhibitors

During HIV-1 genome replication, the viral reverse transcriptase-associated ribonuclease H (RT-associated RNase H) activity hydrolyzes the RNA strand of RNA/DNA heteroduplex intermediates. As of today, HIV-1 RNase H inhibitors (RHIs) remain at an investigational level, although none of them reached clinical trials. Therefore, RNase H remains as an attractive target for drug design and development. In this paper, we review the current status of medicinal chemistry strategies aimed at the discovery of novel RHIs, while discussing problems encountered in their characterization and further development, thereby providing an update on recent progress in the field.

A Systematic Review on Synthetic and Antimicrobial Bioactivity of the Multifaceted Hydrazide Derivatives

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To overcome the upsurge of antimicrobial resistance that has emerged in recent years, there is a need for the development of newer hits having satisfying anti-infective activity. Hydrazides incorporated with an azomethine hydrogen account for a cardinal class of molecules for the development of newer derivatives. Hydrazide derivatives have gained considerable interest of medicinal chemists owing to their diverse bioactivity. In the present review, we have attempted to compile the recent trends in the synthesis of hydrazides and their substituted derivatives. The structural features that lead to the desired antimicrobial activity are highlighted, which will lead the way for synthetic and medicinal chemists to focus on newer designs in this arena.

Pyridine Compounds with Antimicrobial and Antiviral Activities

In the context of the new life-threatening COVID-19 pandemic caused by the SARS-CoV-2 virus, finding new antiviral and antimicrobial compounds is a priority in current research. Pyridine is a privileged nucleus among heterocycles; its compounds have been noted for their therapeutic properties, such as antimicrobial, antiviral, antitumor, analgesic, anticonvulsant, anti-inflammatory, antioxidant, anti-Alzheimer’s, anti-ulcer or antidiabetic. It is known that a pyridine compound, which also contains a heterocycle, has improved therapeutic properties. The singular presence of the pyridine nucleus, or its one together with one or more heterocycles, as well as a simple hydrocarbon linker, or grafted with organic groups, gives the key molecule a certain geometry, which determines an interaction with a specific protein, and defines the antimicrobial and antiviral selectivity for the target molecule. Moreover, an important role of pyridine in medicinal chemistry is to improve water solubility due to its poor basicity. In this article, we aim to review the methods of synthesis of pyridine compounds, their antimicrobial and antiviral activities, the correlation of pharmaceutical properties with various groups present in molecules as well as the binding mode from Molecular Docking Studies.

2-(Arylamino)-6-(trifluoromethyl)nicotinic Acid Derivatives: New HIV-1 RT Dual Inhibitors Active on Viral Replication

The persistence of the AIDS epidemic, and the life-long treatment required, indicate the constant need of novel HIV-1 inhibitors. In this scenario the HIV-1 Reverse Transcriptase (RT)-associated ribonuclease H (RNase H) function is a promising drug target. Here we report a series of compounds, developed on the 2-amino-6-(trifluoromethyl)nicotinic acid scaffold, studied as promising RNase H dual inhibitors. Among the 44 tested compounds, 34 inhibited HIV-1 RT-associated RNase H function in the low micromolar range, and seven of them showed also to inhibit viral replication in cell-based assays with a selectivity index up to 10. The most promising compound, 21, inhibited RNase H function with an IC50 of 14 µM and HIV-1 replication in cell-based assays with a selectivity index greater than 10. Mode of action studies revealed that compound 21 is an allosteric dual-site compound inhibiting both HIV-1 RT functions, blocking the polymerase function also in presence of mutations carried by circulating variants resistant to non-nucleoside inhibitors, and the RNase H function interacting with conserved regions within the RNase H domain. Proving compound 21 as a promising lead for the design of new allosteric RNase H inhibitors active against viral replication with not significant cytotoxic effects.

Synthesis, biology, computational studies and in vitro controlled release of new isoniazid-based adamantane derivatives

Aim: There is a necessity for new drugs to be more efficient than today's standard due to the emergence of drug-resistant strains of Mycobacterium tuberculosis (Mtb) Results/methodology: 12 new isoniazid-based adamantane derivatives were synthesized and tested for their antitubercular activity. The pharmacological test results and the aqueous dissolution profile of representative examples of the new molecules are in agreement with the computational results obtained from docking poses and molecular dynamics simulations on the tested compounds. Conclusion: Among their congeners, the adamantane isonicotinoyl hydrazones Ia and Ih exhibit the best antitubercular activity (MIC = 0.04 μg/ml) and the lowest cytotoxicity (selectivity index ≥2500). These results are useful for in future in vivo studies.

Novel 6-Phenylnicotinohydrazide Derivatives: Design, Synthesis and Biological Evaluation as a Novel Class of Antitubercular and Antimicrobial Agents

In our ongoing efforts to develop potent antitubercular agents based on the 6-phenylnicotinohydrazide, herein we report the design, synthesis and biological evaluation of three sets of 6-phenylnicotinohydrazide derivatives 8a-g, 12 and 16a, b. The designed compounds were synthesized and in vitro evaluated for their antitubercular activity. In addition, their antifungal and antibacterial activities were evaluated as well. The nicotinohydrazide class displayed different levels of antimicrobial activity and possessed a distinctive pattern of selectivity against the tested microorganisms. However, the 2,6-dichlorobenzylidene counterpart 8b emerged as the most active one in this study, with superior antimycobacterial activity (minimum inhibitory concentration (MIC)=3.90 µg/mL) and potent broad-spectrum antimicrobial activities with MIC range of 0.24-1.95 µg/mL. The structure-activity relationship for such nicotinohydrazides has been established. Further, the cytotoxicity of the most active antitubercular compounds 8b, d and g were tested against the normal breast cells WI-38; none of them displayed significant cytotoxic effect, thereby providing a good therapeutic index.

The advancement of multidimensional QSAR for novel drug discovery - where are we headed?

INTRODUCTION

The Multidimensional quantitative structure-activity relationship (multidimensional-QSAR) method is one of the most popular computational methods employed to predict interesting biochemical properties of existing or hypothetical molecules. With continuous progress, the QSAR method has made remarkable success in various fields, such as medicinal chemistry, material science and predictive toxicology. Areas covered: In this review, the authors cover the basic elements of multidimensional -QSAR including model construction, validation and application. It includes and emphasizes the very recent developments of multidimensional -QSAR such as: HQSAR, G-QSAR, MIA-QSAR, multi-target QSAR. The advantages and disadvantages of each method are also discussed and typical examples of their application are detailed. Expert opinion: Although there are defects in multidimensional-QSAR modeling, it is still of enormous help to chemists, biologists and other researchers in various fields. In the authors' opinion, the latest more precise and feasible QSAR models should be further developed by integrating new descriptors, algorithms and other relevant computational techniques. Apart from being applied in traditional fields (e.g. lead optimization and predictive risk assessment), QSAR should be used more widely as a routine method in other emerging research fields including the modeling of nanoparticles(NPs), mixture toxicity and peptides.

QSAR based therapeutic management of M. tuberculosis

Mycobacterium tuberculosis is responsible for severe mortality and morbidity worldwide but, under-developed and developing countries are more prone to infection. In search of effective and wide-spectrum anti-tubercular agents, interdisciplinary approaches are being explored. Of the several approaches used, computer based quantitative structure activity relationship (QSAR) have gained momentum. Structure-based drug design and discovery implies a combined knowledge of accurate prediction of ligand poses with the good prediction and interpretation of statistically validated models derived from the 3D-QSAR approach. The validated models are generally used to screen a small combinatorial library of potential synthetic candidates to identify hits which further subjected to docking to filter out compounds as novel potential emerging drug molecules to address multidrug-resistant tuberculosis. Several newer models are integrated to QSAR methods which include different types of chemical and biological data, and simultaneous prediction of pharmacological activities including toxicities and/or other safety profiles to get new compounds with desired activity. In the process, several newer molecules have been identified which are now being assessed for their clinical efficacy. Present review deals with the advances made in the field highlighting overall future prospects of the development of anti-tuberculosis drugs.

1α,2α-Epoxy-3β-hydroxy oleanolic acid derivatives regulation of the metabolism, haemolysis and β-lactamase gene expression in vitro and their structure-microbicidal activity relationship

Oleanolic acid (OA), one of the major pentacyclic triterpenes abundantly present in nature, is a promising compound with various biological activities, including anti-inflammatory, anti-ulcer, hepatoprotective, antidiabetic, fungicidal and antiparasitic properties. Therefore, a series of derivatives of 1α,2α-epoxy-3β-hydroxyl oleanolic acid derivatives were designed and synthesized, and their antibacterial activities were investigated in vitro. Based on these results, the compounds with antibacterial activity were screened by RT-PCR to determine whether they can regulate the expression of genes related to metabolism, haemolysis, and β-lactamase in vitro, and the structure-microbicidal activity relationship of each compound was analyzed. Our study shows that some of the modifications in the synthetic compounds, such as the introduction of an ortho-cyano-substituted benzyl group and a short chain alkyl ester at the 28-carboxyl, as well as the introduction of an acetyl group at the 3-hydroxyl group of ring A, could enhance antibacterial activity. This provides basic evidence for the optimization of 1α,2α-epoxy-3β-hydroxyl oleanolic acid derivatives. The antibacterial mechanism of the active OA derivatives appears to involve the regulation of expression of metabolism-associated genes in Escherichia coli, haemolysis-associated genes in Bacillus subtilis, metabolism-related genes in Klebsiella pneumonia and β-lactamase-associated genes in Acinetobacter baumannii. Some OA derivatives were bactericidal to three of the strains and appeared to regulate gene expression associated with metabolism, haemolysis, and β-lactamase in vitro. These newly designed OA derivatives possess unique antibacterial activities and may be potentially useful for prophylactic or therapeutic intervention of bacterial infections.

Design, synthesis and antitubercular activity of certain nicotinic Acid hydrazides

Three series of 6-aryl-2-methylnicotinohydrazides 4a–i, N′-arylidene-6-(4-bromophenyl)-2-methylnicotino hydrazides 7a–f, and N′-(un/substituted 2-oxoindolin-3-ylidene)-6-(4-fluorophenyl)-2-methylnicotinohydrazides 8a–c were synthesized and evaluated for their potential in vitro antimycobacterial activity against M. tuberculosis. The results showed that isatin hydrazides 8a–c are remarkably more active than the parent hydrazide 4c. Hydrazides 8b and 8c exhibited the highest activity among all the tested compounds (MIC = 12.5 and 6.25 µg/mL, respectively). Compounds 8b and 8c were also devoid of apparent cytotoxicity to HT-29, PC-3, A549, HepG2 and MCF-7 cancer cell lines. Besides, 8b and 8c showed good drug-likeness scores of 0.62 and 0.41, respectively. Those two isatin hydrazides could offer an excellent framework for future development to obtain more potent antitubercular agents. The SAR study suggested that lipophilicity of the synthesized derivatives is a crucial element that accounts for their antimycobacterial activity. Finally, a theoretical kinetic study was established to predict the ADME of the active derivatives.

Synthesis, antimicrobial, anticancer, antiviral evaluation and QSAR studies of 4-(1-aryl-2-oxo-1,2-dihydro-indol-3-ylideneamino)-N-substituted benzene sulfonamides

A series of 4-(1-aryl-2-oxo-1,2-dihydro-indol-3-ylideneamino)-N-substituted benzenesulfonamide derivatives (1-32) was synthesized and evaluated for its in vitro antimicrobial, antiviral and cytotoxic activities. Antimicrobial results indicated that compounds (11) and (18) were found to be the most effective ones. In general, the synthesized compounds were bacteriostatic and fungistatic in their action. The cytotoxic screening results indicated that the compounds were less active than the standard drug 5-fluorouracil (5-FU). None of the compounds inhibited viral replication at subtoxic concentrations. In general, the presence of a pyrimidine ring with electron releasing groups and an ortho- and para-substituted benzoyl moiety favored antimicrobial activities. The results of QSAR studies demonstrated the importance of topological parameters, valence zero order molecular connectivity index (0χv) and valence first order molecular connectivity index (1χv) in describing the antimicrobial activity of synthesized compounds.

Therapeutic potential of hydrazones as anti-inflammatory agents

Hydrazones are a special class of organic compounds in the Schiff base family. Hydrazones constitute a versatile compound of organic class having basic structure (R₁R₂C=NNR₃R₄). The active centers of hydrazone, that is, carbon and nitrogen, are mainly responsible for the physical and chemical properties of the hydrazones and, due to the reactivity toward electrophiles and nucleophiles, hydrazones are used for the synthesis of organic compound such as heterocyclic compounds with a variety of biological activities. Hydrazones and their derivatives are known to exhibit a wide range of interesting biological activities like antioxidant, anti-inflammatory, anticonvulsant, analgesic, antimicrobial, anticancer, antiprotozoal, antioxidant, antiparasitic, antiplatelet, cardioprotective, anthelmintic, antidiabetic, antitubercular, trypanocidal, anti-HIV, and so forth. The present review summarizes the efficiency of hydrazones as potent anti-inflammatory agents.

N'-[4-[(Substituted imino)methyl]benzylidene]-substituted benzohydrazides: synthesis, antimicrobial, antiviral, and anticancer evaluation, and QSAR studies

ABSTRACT

A variety of N'-[4-[(substituted imino)methyl]benzylidene]-substituted benzohydrazides have been synthesized and evaluated for antimicrobial and anticancer potential. Results from testing of antimicrobial activity indicated the most potent antimicrobial agents had pMIC am = 1.51. The synthesized compounds were bacteriostatic and fungistatic in action. Results from evaluation of antiviral activity indicated that none of the synthesized hydrazide derivatives inhibited viral replication at sub-toxic concentrations. Results from anti-HIV screening against HIV-2 strain ROD indicated that one compound was more potent (IC 50 ≥ 1 μg/cm3) than the standard drug nevirapine (IC 50 ≥ 4 μg/cm3) and another was equipotent (IC 50 ≥ 4 μg/cm3). The most effective anticancer agent against both HCT116 and MCF7 cancer cell lines had IC 50 = 19 and 18 μg/cm3, respectively. QSAR analysis indicated the importance of Wiener index (W) and energy of the lowest unoccupied molecular orbital (LUMO) in describing the antimicrobial activity of the synthesized compounds.

GRAPHICAL ABSTRACT