Synthesis, in vitro, and in vivo (Zebra fish) antitubercular activity of 7,8-dihydroquinolin-5(6H)-ylidenehydrazinecarbothioamides

In-vitro and in-silico investigations of SLC-0111 hydrazinyl analogs as human carbonic anhydrase I, II, IX, and XII inhibitors

Two novel series of hydrazinyl-based benzenesulfonamides 9a-j and 10a-j were designed and synthesized using SLC-0111 as the lead molecule. The newly synthesized compounds were evaluated for their inhibitory activity against four different human carbonic anhydrase (hCA) isoforms I, II, IX, and XII. Both the series reported here were practically inactive against the off-target isozyme hCA I. Notably, derivative 10a exhibited superior potency (Ki of 10.2 nM) than acetazolamide (AAZ) against the cytosolic isoform hCA II. The hCA IX and XII isoforms implicated in tumor progression were effectively inhibited with Kis in the low nanomolar range of 20.5-176.6 nM and 6.0-127.5 nM, respectively. Compound 9g emerged as the most potent and selective hCA IX and XII inhibitor with Ki of 20.5 nM and SI of 200.1, and Ki of 6.0 nM and SI of 683.7, respectively, over hCA I. Furthermore, six compounds (9a, 9h, 10a, 10g, 10i, and 10j) exhibited significant inhibition toward hCA IX (Kis = 27.0, 41.1, 27.4, 25.9, 40.7, and 30.8 nM) relative to AAZ and SLC-0111 (Kis = 25.0 and 45.0 nM, respectively). These findings underscore the potential of these derivatives as potent and selective inhibitors of hCA IX and XII over the off-target hCA I and II.

Chemoselective Condensation of 3-Amino-2-cyclohexenones with Cinnamaldehydes: Switchable Synthesis of Dihydroquinolinones and Hexahydroacridinediones

Herein, a chemoselective condensation of 3-amino-2-cyclohexenones and cinnamaldehydes for switchable synthesis of dihydroquinolinones and hexahydroacridinediones was developed. Mechanism analysis showed that the formation of dihydroquinolinones involved trimolecular condensation and oxidative aromatization, while the formation of hexahydroacridinediones involved acid hydrolysis of enaminone and dehydration-aromatization. This strategy provides a convenient way to switch from the same substrates to produce two different quinolinone derivatives.

QSAR Studies, Molecular Docking, Molecular Dynamics, Synthesis, and Biological Evaluation of Novel Quinolinone-Based Thiosemicarbazones against Mycobacterium tuberculosis

In this study, a series of novel quinolinone-based thiosemicarbazones were designed in silico and their activities tested in vitro against Mycobacterium tuberculosis (M. tuberculosis). Quantitative structure-activity relationship (QSAR) studies were performed using quinolinone and thiosemicarbazide as pharmacophoric nuclei; the best model showed statistical parameters of R² = 0.83; F = 47.96; s = 0.31, and was validated by several different methods. The van der Waals volume, electron density, and electronegativity model results suggested a pivotal role in antituberculosis (anti-TB) activity. Subsequently, from this model a new series of quinolinone-thiosemicarbazone 11a-e was designed and docked against two tuberculosis protein targets: enoyl-acyl carrier protein reductase (InhA) and decaprenylphosphoryl-β-D-ribose-2'-oxidase (DprE1). Molecular dynamics simulation over 200 ns showed a binding energy of -71.3 to -12.7 Kcal/mol, suggesting likely inhibition. In vitro antimycobacterial activity of quinolinone-thiosemicarbazone for 11a-e was evaluated against M. bovis, M. tuberculosis H37Rv, and six different strains of drug-resistant M. tuberculosis. All compounds exhibited good to excellent activity against all the families of M. tuberculosis. Several of the here synthesized compounds were more effective than the standard drugs (isoniazid, oxafloxacin), 11d and 11e being the most active products. The results suggest that these compounds may contribute as lead compounds in the research of new potential antimycobacterial agents.

Domino synthesis of functionalized pyridine carboxylates under gallium catalysis: Unravelling the reaction pathway and the role of the nitrogen source counter anion

The catalytic potential of various metal Lewis acid catalysts have been assessed to derive a high-yielding, multi-component domino synthesis of functionalized pyridines from (E)-3-(dimethylamino)-1-aryl/heteroaryl-prop-2-en-1-ones, 1,3-dicarbonyl compounds, and an ammonium salt (as the nitrogen precursor). Amongst the various metal halides, tetrafluoroborates, perchlorates, and triflates used as the catalyst GaI3 proved to be the most effective. The mechanistic course of the most plausible pathway has been outlined as the intermediate formation of imine/enamine by the reaction of the 1,3-dicarbonyl compound with ammonia (liberated in situ from the ammonium salt used as the nitrogen source), which participates in the domino nucleophilic Michael reaction to the (2E)-3-(dimethylamino)-1-aryl/hetroarylprop-2-en-1-one by its active methylene carbon through its enamine form followed by intramolecular cyclization and aromatization. The effect of different ammonium salts as the nitrogen source has been investigated and NH4OAc was found to be best. The influence of the acetate counter anion of NH4OAc on the progress of the reaction was studied and its specific role in the cyclization and subsequent aromatization has been revealed. This work offers distinct advantages compared to the literature reported methodologies on the count of several green index parameters.

The role of alternative toxicological trials in drug discovery programs: The case of Caenorhabditis elegans and other methods

The discovery of a new drug requires over a billion dollars and around 12 years of research efforts, and toxicity is the leading reason for failure to approve candidate drugs. Many alternative methods have been validated to detect toxicity as early as possible to diminish the waste of resources and efforts in medicinal chemistry research, and in vivo alternative methods are especially valuable for the amount of information they can give at little cost and in a short time. In this work, we present a review of the literature published between the years 2000 and 2021 of in vivo alternative methods of toxicity screening employed in medicinal chemistry, which we believe will be useful because, in addition to shortening research times, these studies provide much additional information aside from the toxicity of drug candidate compounds. These in vivo models include zebrafish, Artemia salina, Galleria mellonella, Drosophila melanogaster, planarians, and Caenorhabditis elegans as highlights. The most published ones in the last decade were zebrafish, D. melanogaster and C. elegans due to their reliability, ease and cost-effectiveness of implementation and flexibility. Special attention is given to C. elegans because of its rising popularity, a wide range of uses including toxicity screening, and active effects measurement, from antioxidant effects to anthelmintic and antimicrobial activities, and its fast and reliable results. Over time, C. elegans also became a viable high-throughput (HTS) automated drug screening option. Additionally, this manuscript lists briefly the other screening methods used for the initial toxicological analyses and the role of alternative in vivo methods in these scenarios, classifying them as in silico, in vitro and alternative in vivo models, the latter of which have been receiving a growing increase in interest in recent years.

Imidazole-Thiosemicarbazide Derivatives as Potent Anti-Mycobacterium tuberculosis Compounds with Antibiofilm Activity

Mycobacterium tuberculosis (Mtb) is an intracellular pathogenic bacterium and the causative agent of tuberculosis. This disease is one of the most ancient and deadliest bacterial infections, as it poses major health, social and economic challenges at a global level, primarily in low- and middle-income countries. The lack of an effective vaccine, the long and expensive drug therapy, and the rapid spread of drug-resistant strains of Mtb have led to the re-emergence of tuberculosis as a global pandemic. Here, we assessed the in vitro activity of new imidazole-thiosemicarbazide derivatives (ITDs) against Mtb infection and their effects on mycobacterial biofilm formation. Cytotoxicity studies of the new compounds in cell lines and human monocyte-derived macrophages (MDMs) were performed. The anti-Mtb activity of ITDs was evaluated by determining minimal inhibitory concentrations of resazurin, time-kill curves, bacterial intracellular growth and the effect on biofilm formation. Mutation frequency and whole-genome sequencing of mutants that were resistant to ITDs were performed. The antimycobacterial potential of ITDs with the ability to penetrate Mtb-infected human macrophages and significantly inhibit the intracellular growth of tubercle bacilli and suppress Mtb biofilm formation was observed.

Synthesis, antitubercular, antimicrobial activities and molecular docking study of quinoline bearing dihydropyrimidines

In order to develop the antimicrobial and antitubercular agents, we have derived quinoline bearing dihydropyrimidine analogues 5a-o and structures of these compounds were determined by spectroscopic techniques. Further, we have calculated the molecular properties prediction and drug-likeness by Molinspiration property calculation toolkit and MolSoft software, respectively. The most active compound against Mycobacterium tuberculosis (5m, MIC = 0.20 µg/mL) also possessed a maximum drug-likeness model score (0.42). Compounds 5m, 5g and 5k were possessed promising antibacterial activity against tested bacterial species. Compound 5k was the only compound to have eye-catcher antifungal activity. Furthermore, the MTT cytotoxicity results on HeLa cells suggested lower cytotoxicity of biologically active compounds. Supramolecular interactions of the synthesized compounds has been assessed my means of molecular docking studies. Although all the synthesized compounds are showing preferably good interactions with their respective proteins, their binding free energies values suggest that these molecules are preferred for antitubercular activity rather than antimicrobial activity.

Analysis of Approaches to Anti-tuberculosis Compounds

Mycobacterium tuberculosis (Mtb) remains a deadly pathogen two decades after the announcement of tuberculosis (TB) as a global health emergency by the World Health Organization. Medicinal chemistry efforts to synthesize potential drugs to shorten TB treatments have not always been successful. Here, we analyze physiochemical properties of 39 TB drugs and 1271 synthetic compounds reported in 40 publications from 2006 to early 2020. We also propose a new TB space of physiochemical properties that may provide more appropriate guidelines for design of anti-TB drugs.