Quinoline Derivatives as Promising Scaffolds for Antitubercular Activity: A Comprehensive Review.

BACKGROUND: Heterocyclic compounds and their derivatives play a significant role in the design and development of novel quinoline drugs. Among the various pharmacologically active heterocyclic compounds, quinolines stand out as the most significant rings due to their broad pharmacological roles, specifically antitubercular activity, and their presence in plant-based compounds. Quinoline is also known as benzpyridine, benzopyridine, and 1-azanaphthalene. It has a benzene ring fused with a pyridine ring, and both rings share two carbon atoms. The importance of quinoline lies in its incorporation as a key component in various natural compounds found in medicinal plant families like Fumariaceae, Berberidaceae, Rutaceae, Papavaraceae, and others. OBJECTIVE: This article is expected to have a significant impact on the advancement of effective antitubercular drugs. Through harnessing the potent activity of quinoline derivatives, the research aims to make valuable contributions to combating tuberculosis more efficiently and ultimately reducing the global burden of this infectious disease. METHODS: Numerous nitrogen-containing heterocyclic compounds exhibit significant potential as antitubercular agents. These chemicals have fused aromatic nitrogen-heterocyclic nuclei that can change the number of electrons they have, which can change their chemical, physical, and biological properties. This versatility comes from their ability to bind with the receptors in multiple modes, a critical aspect of drug pharmacological screening. Among these compounds, quinoline stands out as it incorporates a stable fusion of a benzene ring with a pyridine nucleus. Quinolines have demonstrated a diverse range of pharmacological activities, including but not limited to anti-tubercular, anti-tumor, anticoagulant, anti-inflammatory, antioxidant, antiviral, antimalarial, anti-HIV, and antimicrobial effects. RESULTS: Some molecules, such as lone-paired nitrogen species, include pyrrole, pyrazole, and quinoline. These molecules contain nitrogen and take part in metabolic reactions with other molecules inside the cell. However, an excessive accumulation of reactive nitrogen species can lead to cytotoxicity, resulting in damage to essential biological macromolecules. Among these compounds, quinoline stands out as the oldest and most effective one, exhibiting a wide range of significant properties such as antitubercular, antimicrobial, anti-inflammatory, antioxidant, analgesic, and anticonvulsant activities. Notably, naturally occurring quinoline compounds, such as quinine, have proven to be potent antimalarial drugs. CONCLUSION: This review highlights quinoline derivatives' antitubercular potential, emphasizing recent research advancements. Utilizing IC50 values, the study emphasizes the efficacy of various quinoline substitutions, hybrids, and electron-withdrawing groups against MTB H37Rv. Continued research is essential for developing potent, low-toxicity quinoline derivatives to combat tuberculosis.

Chemical Characterization, In-silico Evaluation, and Molecular Docking Analysis of Antiproliferative Compounds Isolated from the Bark of Anthocephalus cadamba Miq.

AIMS: The present study aimed to isolate and characterize chemical compounds from Anthocephalus cadamba Miq. bark and evaluate their anticancer activity by in silico, molecular docking, and in vitro studies. BACKGROUND: Anthocephalus cadamba is a traditionally used Indian medicinal plant. The anticancer and phytochemical properties of this plant remain unexplored except for a few studies. OBJECTIVES: The objective of the study was to evaluate the antiproliferative activity of extract and fractions against breast cancer and prostate cancer cell lines and isolate and characterize active compounds from bio-active guided fractions. Moreover, the anticancer activity of isolated compounds against breast and prostate cancer cell lines was also evaluated, in addition to in silico and molecular docking interactions of isolated compounds with VEGFR2 and PDGFRα target proteins. METHODS: The compounds were isolated and purified with the help of repeated column chromatography, and spectral techniques, such as 1D, 2D NMR, and GC-MS/MS, were used to identify and elucidate the structure of the compounds. Moreover, prediction of activity spectra for substances, physiochemical properties, bioactivity radar prediction, bioactivity score, natural-product likeness, ADME, and toxicity parameters of isolated compounds (AC-1 to AC-4) was performed through various in-silico databases and servers. To evaluate the docking interaction profile and binding energies of compounds, three docking tools were utilized, such as AutoDock, AutoDock Vina, and iGEMDOCK, against two targets VEGFR2 and PDGFRα. MD simulation was performed through ligand and receptor molecular dynamic server (LARMD). RESULTS: It was found that the A. cadamba bark chloroform fraction demonstrated a significant inhibitory effect against MDA-MB-231, MCF-7, and PC-3 cells in a dose-time-dependent manner. The bioassay-guided isolation afforded four molecules AC-1 to AC-4 from chloroform fraction. Moreover, the GC-MS/MS profiling identified fourteen new molecules which were not reported earlier from A. cadamba. The in-silico study showed that the isolated compounds (AC-1 to AC-4) followed Lipinski's rule and had good oral bioavailability. While compound AC-4 had positive bioactivity scores except for kinase inhibitor activity. The ADMET profiling revealed that AC-4 was non-toxic and easily absorbed in the human intestine, and transportable in the blood-brain barrier compared to AC-1, AC-2, AC-3, and standard drug doxorubicin. Molecular docking and MD simulation assessment also signified AC-4 anticancer activity with dual inhibitory action against the target proteins VEGFR2 and PDGFRα amongst the studied compounds. The in vitro cell viability assay of isolated compounds demonstrated that AC-1 showed IC50 (µg/mL) value of 34.96 ±3.91, 47.76±3.80 69.1±4.96, AC-2; 68.26±4.22, 54.03±5.14, >100, AC-3; 35.34±4.14, 51.5±51.5, 70.8±5.25 and AC-4; 44.2±3.57, 24.2±2.67, 51.2±2.54 for MDA-MB-231, MCF-7, and PC-3 cancer cell lines, respectively and compared with standard drug doxorubicin. Moreover, fluorescence microscopy confirmed the apoptogenic property of compounds. We also found that AC-4 exhibited significant intracellular ROS production in breast cancer cells, thereby inducing apoptosis and eventually cell death. CONCLUSION: In conclusion, A. cadamba afforded four pure molecules AC-1 to AC-4 with the identification of fourteen new compounds. The entire in-silico studies concluded that the AC-4 compound had better oral bioavailability, bioactivity score, and ADMET profile among studied molecules. Molecular docking analysis and MD simulation also supported AC-4 dual inhibitory action against both VEGFR2 and PDGFRα receptors. Moreover, the isolated molecules AC-1, AC-2, AC-3, and AC-4 were found to be active against MDA-MB-231, MCF-7, and PC-3 cancer cells. The molecule AC-4 was found to induce ROS-mediated apoptosis in breast cancer cells. It was found that the anticancer inhibitory potentiality of AC-4 is directed to its molecular stereochemistry which specifically binds to the target proteins of breast cancer cells with no toxicological effect. Therefore, AC-4 is suggested to be an effective aspirant for novel drug design and discovery.

Identification of Severe Acute Respiratory Syndrome Coronavirus-2 inhibitors through in silico structure-based virtual screening and molecular interaction studies.

The novel coronavirus Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) or COVID-19 has caused a worldwide pandemic. The fatal virus has affected the health of human beings as well as the socio-economic situation all over the world. To date, no concrete medicinal solution has been proposed to combat the viral infection, calling for an urgent, strategic, and cost-effective drug development approach that may be achievable by applying targeted computational and virtual screening protocols. Immunity is the body's natural defense against disease-causing pathogens, which can be boosted by consuming plant-based or natural food products. Active constituents derived from natural sources also scavenge the free radicals and have anti-inflammatory activities. Herbs and spices have been used for various medicinal purposes. In this study, 2,96 365 natural and synthetic derivatives (ligands) belonging to 102 classes of compounds were obtained from PubChem and assessed on Lipinski's parameters for their potential bioavailability. Out of all the derivatives, 3254 obeyed Lipinski's rule and were virtually screened. The 115 top derivatives were docked against SARS-CoV-2, SARS-CoV, MERS-CoV, and HCoV-HKV1 main proteases (Mpro s) as receptors using AutoDock Vina, AutoDock, and iGEMDOCK 2.1. The lowest binding energy was exhibited by ligands 2 and 6 against all the four Mpro s. The molecular dynamic simulation was also performed with ligand 6 using the GROMACS package. Good bioactivity scores, absorption, distribution, metabolism, excretion, and toxicity profile and drug-like pharmacokinetic parameters were also obtained. Hydroxychloroquine was used as the control drug.

Computer-aided drug design and virtual screening of targeted combinatorial libraries of mixed-ligand transition metal complexes of 2-butanone thiosemicarbazone.

The present paper deals with in silico evaluation of 32 virtually designed transition metal complexes of 2-butanone thiosemicarbazone and N,S,O containing donor hetero-ligands namely py, bpy, furan, thiophene, 2-picoline, 1,10-phenanthroline, piperazine and liquid ammonia. The complexes were designed with a view to assess their potential anticancer, antioxidant and antibacterial activity. The absorption, distribution, metabolism, excretion and toxicity (ADMET) properties of the chosen ligands were calculated by admetSAR software. Metabolic sites of different ligands likely to undergo metabolism were predicted using Metaprint 2D. The proposed complexes were also evaluated for their drug-like quality based on Lipinski's, Veber, Ghose and leadlikeness filters. Druglikeness and toxicity potential were predicted by OSIRIS property explorer. The pharmacokinetic properties and bioactivity scores were calculated by Molinspiration tool. Bioactivity scores of the complexes were predicted for drug targets including enzymes, nuclear receptors, kinase inhibitors, G-protein coupled receptor ligands and ion channel modulators. Molecular docking of selected Fe(II) mixed-ligand complexes was performed using AutoDock version 4.2.6 and i-GEMDOCK version 2.1 with two target proteins namely Ribonucleotide reductase (RR) and Topoisomerase II (Topo II). The results were compared with three standard reference drugs viz. Doxorubicin HCl, Letrozole (anticancer) and Tetracycline (antibiotic). Multivariate data obtained were analyzed using principal component analysis (PCA) for visualization and projection as scatter and 3D plots. Positive results obtained for hetero-ligands using admetSAR version 1.0 indicated good absorption and transport kinetics of the hetero-ligand complexes through the human intestine and blood-brain barrier. The hetero-ligands were predicted to have no associated mutagenic effect(s) also. However, none of the hetero-ligands was predicted to be Caco-2 (human colon cancer cell line) permeable. Most of the hetero-ligands and the parent ligand (2-butanone thiosemicarbazone) were predicted to undergo Phase-I metabolism prior to excretion using MetaPrint2D software. Pharmacokinetic evaluation of the proposed complexes revealed that all complexes displayed drug-like character and were predicted to have no apparent toxic side-effects. All the proposed complexes showed moderate to good biological activity scores (-5.0 to 0.0). Mixed complexes with bpy, 2-picoline and 1,10-phenanthroline showed significant bioactivity scores (as enzyme inhibitors) in the range 0.02-0.13. Likewise, good docking scores were obtained for Fe (II) complexes with the same ligands. [FeL(2-pic)2] displayed the lowest binding energy (-6.47 kcal/mol) with respect to Topo II followed by [FeL(py)2] (-6.14 kcal/mol) as calculated by AutoDock version 4.2.6. With respect to binding with RR, [FeL(2--pic)2] again displayed the lowest binding energy (-7.21 kcal/mol) followed by [FeL(py)2] (-5.96 kcal/mol). On the basis of docking predictions and various other computational evaluations, four mixed-ligand complexes of Fe in +2 oxidation state with py, bpy, 2--picoline and 1,10-phenanthroline were synthesized with 2-butanone thiosemicarbazone. All the synthesized Fe complexes were characterized using various spectroscopic techniques and tested for their potential anticancer activity in vitro against human breast carcinoma cell line MDA-MB 231 and human lung carcinoma cell line A549 cell line using MTT assay. [FeL(2-pic)2], [FeL(bpy)], and [FeL(py)2] were found to exhibit significant antiproliferative activity with IC50 values in the range of 80-100 µM against breast and lung cancer cells. The synthesized Fe complexes also displayed mild antioxidant activities. The synthesized and studied Fe complexes have the potential for development into future anticancer agents if analyzed and modified further for improvement of their ADMET, solubility and permeability criteria set for potential drug-candidates.