Discovery of ( ±)-3-(1H-pyrazol-1-yl)-6,7-dihydro-5H-[1,2,4]triazolo[3,4-b][1,3,4] thiadiazine derivatives with promising in vitro anticoronavirus and antitumoral activity

Design, synthesis, molecular docking, and dynamic studies of novel thiazole derivatives incorporating benzimidazole moiety and assessment as antibacterial agents

A general and sustainable approach for the synthesis of benzimidazole-thiazole compounds via an efficient, one-pot, domino, pseudo-four-component reaction using 5-amino-2-mercaptobenzimidazole, aralkyl halides, ammonium thiocyanate, and substituted α-bromo-acetophenones in glacial acetic acid at ambient temperature to give final compounds (4a-p) in good yields in shorter time. The spectral data of synthesized compounds were evaluated by analytical and spectral techniques (IR, 1H-NMR, 13C-NMR, and ESI-HRMS). Further, some of the synthesized compounds were screened for their in-vitro antibacterial activity studies using the agar well diffusion method against Gram-positive Streptococcus pneumoniae (2451) bacteria and Gram-negative Proteous mirabilis (2081) bacteria. Based on the MIC results, it was observed that the most active compounds 4b, 4e, 4f, and 4k show promising antibacterial activity with the zone of inhibition values of 2.85 cm 2.75 cm, 3.6 cm, and 3.3 cm against both Gram-negative and positive bacteria cell lines, respectively. Further, we have also insight into the molecular simulation studies, based on the binding results, compound 4i showed stable binding interactions with streptomycin drug with the active site of the gyrase protein (PDB ID: 1KIJ). The structure-activity relationship (SAR) studies of all the title scaffolds were also established. The antibacterial activity, molecular docking studies, and molecular dynamic simulations of the title compounds suggested that these are promising antibacterial active skeletons.

Recent Advances in Nitrogen-Containing Heterocyclic Scaffolds as Antiviral Agents

This study aims to provide a thorough analysis of nitrogen-containing heterocycles, focusing on their therapeutic implications for the development of targeted and effective antiviral drugs. To better understand how nitrogen-containing heterocycles can be used to create antiviral drugs, this review adopts a systematic literature review strategy to compile and analyze pertinent research studies. It combines information from various fields to understand better the compounds' mode of action and their therapeutic potential. This review paper summarizes data from multiple sources to highlight the promising potential of heterocycles containing nitrogen as promising possibilities for future antiviral treatments. The capacity to engage selectively and modulate critical pathways bodes well for their use in developing new viral therapies. In conclusion, nitrogen-containing heterocycles are shown to be of utmost importance in the field of medicinal chemistry, as emphasized by the review paper. It emphasizes the central importance of chemical insights and pharmacological potential in developing novel and effective antiviral medicines by bringing them together.

Synthesis, molecular docking and dynamics studies of pyridazino[4,5-b]quinoxalin-1(2H)-ones as targeting main protease of COVID-19

The COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has created a crisis in public health. Because, the 3CLpro, the main protease of SARS-CoV-2, possesses a critical role in coronavirus replication, many efforts have been devoted to developing various inhibitors to prevent the fast spread of COVID-19. In the current work, a number of various pyridazino[4,5-b]quinoxalin-1(2H)-one derivatives bearing thiadiazine and thiadiazole fragments has been prepared via a straightforward and practical strategy involving the reaction of 2-(ethoxycarbonyl)-3-formylquinoxaline 1,4-dioxide with thiocarbohydrazide under reflux conditions. To determine the bioavailability of pyridazino[4,5-b]quinoxalin-1(2H)-one derivatives, Lipinski's rule of five has been carried out. Regarding this rule, none of the synthesized compounds exhibit any deviation from Lipinski's rule of five. Furthermore, molecular docking and molecular dynamics approaches have been implemented to figure out the potential interactions of products with SARS-CoV-2 main protease. The outcomes of molecular docking studies demonstrate that the phenyl and nitrophenyl substituted pyridazino[4,5-b]quinoxalin-1(2H)-one show the lowest binding affinity among the other compounds, indicating a favorable orientation in the active site of the chymotrypsin-like cysteine protease. In addition, the MD simulation performed to evaluate the stability of the protein-ligand complex represents that the average binding energy of the nitrophenyl complex is less than that of the phenyl complex. Therefore, according to the in silico results, the inhibitory effect of the nitrophenyl complex is more significant than the phenyl complex.Communicated by Ramaswamy H. Sarma.

Synthesis, X-ray crystal structure, Hirshfeld surface analysis and computational investigation into the potential inhibitory action of novel 6-(p-tolyl)-2-((p-tolyl)thio)methyl-7H-[1.2.4]triazolo[5,1-b][1,3,4]thiadiazine inhibits the main protease of COVID-19

In recent times, the novel coronavirus disease (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has now become a worldwide pandemic. With over 71 million confirmed cases, even though the effectiveness and side effects of the specific drugs and vaccines approved for this disease are still limited. Scientists and researchers from all across the world are working to find a vaccine and a cure for COVID-19 by using large-scale drug discovery and analysis. Heterocyclic compounds are regarded to be valuable sources for the discovery of new antiviral medications against SARS-CoV-2 because virus occurrences are still on the rise, and infectivity and mortality may also rise shortly. In this regard, we have synthesized a new triazolothiadiazine derivative. The structure was characterized by NMR spectra and confirmed by X-ray diffraction analysis. The structural geometry coordinates of the title compound are well reproduced by DFT calculations. NBO and NPA analyses have been performed to determine the interaction energies between bonding and antibonding orbital, and natural atomic charges of heavy atoms. Molecular docking suggests that the compounds may have good affinity for SAR-CoV-2 main protease, RNA-dependent RNA polymerase and nucleocapsid enzymes, particularly the main protease enzyme (binding energy of -11.9 kcal mol-1). The predicted docked pose of the compound is dynamically stable and reports a major van der Waals contribution (-62.00 kcal mol-1) to overall net energy.Communicated by Ramaswamy H. Sarma.

Recent Applications of the Multicomponent Synthesis for Bioactive Pyrazole Derivatives

Pyrazole and its derivatives are considered a privileged N-heterocycle with immense therapeutic potential. Over the last few decades, the pot, atom, and step economy (PASE) synthesis of pyrazole derivatives by multicomponent reactions (MCRs) has gained increasing popularity in pharmaceutical and medicinal chemistry. The present review summarizes the recent developments of multicomponent reactions for the synthesis of biologically active molecules containing the pyrazole moiety. Particularly, it covers the articles published from 2015 to date related to antibacterial, anticancer, antifungal, antioxidant, α-glucosidase and α-amylase inhibitory, anti-inflammatory, antimycobacterial, antimalarial, and miscellaneous activities of pyrazole derivatives obtained exclusively via an MCR. The reported analytical and activity data, plausible synthetic mechanisms, and molecular docking simulations are organized in concise tables, schemes, and figures to facilitate comparison and underscore the key points of this review. We hope that this review will be helpful in the quest for developing more biologically active molecules and marketed drugs containing the pyrazole moiety.

Novel Dioxolane Ring Compounds for the Management of Phytopathogen Diseases as Ergosterol Biosynthesis Inhibitors: Synthesis, Biological Activities, and Molecular Docking

Thirty novel dioxolane ring compounds were designed and synthesized. Their chemical structures were confirmed by ¹H NMR, HRMS, and single crystal X-ray diffraction analysis. Bioassays indicated that these dioxolane ring derivatives exhibited excellent fungicidal activity against Rhizoctonia solani, Pyricularia oryae, Botrytis cinerea, Colletotrichum gloeosporioides, Fusarium oxysporum, Physalospora piricola, Cercospora arachidicola and herbicidal activity against lettuce (Lactuca sativa), bentgrass (Agrostis stolonifera), and duckweed (Lemna pausicostata). Among these compounds, 1-((2-(4-chlorophenyl)-5-methyl-1,3-dioxan-2-yl)methyl)-1H-1,2,4-triazole (D17), 1-(((4R)-2-(4-chlorophenyl)-4-methyl-1,3-dioxolan-2-yl)methyl)-1H-1,2,4-triazole (D20), 1-((5-methyl-2-(4-(trifluoromethyl)phenyl)-1,3-dioxan-2-yl)methyl)-1H-1,2,4-triazole (D22), and 1-((2-(4-fluorophenyl)-1,3-dioxolan-2-yl)methyl)-1H-1,2,4-triazole (D26) had broad spectrum fungicidal and herbicidal activity. The IC₅₀ values against duckweed were 20.5 ± 9.0, 14.2 ± 6.7, 24.0 ± 11.0, 8.7 ± 3.5, and 8.0 ± 3.1 μM for D17, D20, D22, and D26 and the positive control difenoconazole, respectively. The EC₅₀ values were 7.31 ± 0.67, 9.74 ± 0.83, 17.32 ± 1.23, 11.96 ± 0.98, and 8.93 ± 0.91 mg/L for D17, D20, D22, and D26 and the positive control difenoconazole against the plant pathogen R. solani, respectively. Germination experiments with Arabidopsis seeds indicated that the target of these dioxolane ring compounds in plants is brassinosteroid biosynthesis. Molecular simulation docking results of compound D26 and difenoconazole with fungal CYP51 P450 confirmed that they both inhibit this enzyme involved in ergosterol biosynthesis. The structure-activity relationships (SAR) are discussed by substituent effect, molecular docking, and density functional theory analysis, which provided useful information for designing more active compounds.