Three-component, one-pot synthesis of anthranilamide Schiff bases bearing 4-aminoquinoline moiety as Mycobacterium tuberculosis gyrase inhibitors

7-Chloroquinolinehydrazones as First-in-Class Anticancer Experimental Drugs in the NCI-60 Screen among Different Investigated Series of Aryl, Quinoline, Pyridine, Benzothiazole and Imidazolehydrazones

In the context of a continuously increasing global cancer risk, the search for new effective and affordable anticancer drugs remains a constant demand. This study describes chemical experimental drugs able to destroy cancer cells by arresting their growth. New hydrazones with quinoline, pyridine, benzothiazole and imidazole moieties have been synthesized and evaluated for their cytotoxic potential against 60 cancer cell lines. 7-Chloroquinolinehydrazones were the most active in the current study and exhibited good cytotoxic activity with submicromolar GI₅₀ values on a large panel of cell lines from nine tumor types (leukemia, non-small cell lung cancer, colon cancer, CNS cancer, melanoma, ovarian cancer, renal cancer, prostate cancer and breast cancer). This study provided consistent structure-activity relationships in this series of experimental antitumor compounds.

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.

Design and synthesis of new 3-((7-chloroquinolin-4-yl)amino)thiazolidin-4-one analogs as Mycobacterium tuberculosis DNA gyrase inhibitors

Background

Tuberculosis is evidently a major health threat among human populations worldwide. The current study presents the synthesis of new 3-((7-chloroquinolin-4-yl)amino)thiazolidin-4-one analogs (4a–o) as potential Mycobacterium tuberculosis DNA gyrase inhibitors. DNA gyrase regulates DNA topology in MTB and has been a target of choice for antibacterial therapy. With this in mind, the synthesized derivatives (4a–o) were subjected to in vitro antitubercular evaluation by the MABA method and were tested for MTB DNA gyrase inhibition by supercoiling assay.

Results

All the synthesized compounds displayed inhibition of MTB within the MIC range of 1.56–12.5 μM. Further, out of the selected compounds that underwent DNA gyrase inhibition, compound 4o proved to be a potent lead molecule by displaying 82% of enzyme inhibition at 1 μM. All the synthesized derivatives also underwent molecular docking studies to comprehend their hypothetical binding interactions with Mycobacterium smegmatis GyrB.

Conclusion

All the results suggested that most of the synthesized derivatives inhibited Mycobacterium tuberculosis, and some 3-((7-chloroquinolin-4-yl)amino)thiazolidin-4-one analogs could act as leads for the development of antitubercular agents.

New Schiff bases of 2-(quinolin-8-yloxy)acetohydrazide and their Cu(ii), and Zn(ii) metal complexes: their in vitro antimicrobial potentials and in silico physicochemical and pharmacokinetics properties

The purpose of this work was to prepare Schiff base ligands containing quinoline moiety and using them for preparing Cu(ii) and Zn(ii) complexes. Four bidentate Schiff base ligands (SL1–SL4) with quinoline hydrazine scaffold and a series of mononuclear Cu(ii) and Zn(ii) complexes were successfully prepared and characterized. The in vitro antibacterial and antifungal potential experimentation revealed that the ligands exhibited moderate antibacterial activity against the Gram-positive bacterial types and were inactive against the Gram-negative bacteria and the fungus strains. The metal complexes showed some enhancement in the activity against the Gram-positive bacterial strains and were inactive against the Gram-negative bacteria and the fungus strains similar to the parent ligands. The complex [Cu(SL1)2] was the most toxic compound against both Gram-positive S. aureus and E. faecalis bacteria. The in silico physicochemical investigation revealed that the ligand SL4 showed highest in silico absorption (82.61%) and the two complexes [Cu(SL4)2] and [Zn(SL4)2] showed highest in silico absorption with 56.23% for both compounds. The in silico pharmacokinetics predictions showed that the ligands have high gastrointestinal (GI) absorption and the complexes showed low GI absorption. The ligands showed a good bioavailability score of 0.55 where the complexes showed moderate to poor bioavailability.

Synthesis and biological evaluation of 2-phenyl-4-aminoquinolines as potential antifungal agents

A series of 2-phenyl-4-aminoquinolines were designed, synthesized and evaluated for their antifungal activities against three phytopathogenic fungi in vitro. All of the target compounds were fully elucidated by ¹H NMR, ¹³C NMR and HRMS spectra. The results indicated that most of the target compounds demonstrated significant activities against the tested fungi. Among them, compound 6e exhibited more promising inhibitory activities against C. lunata (EC₅₀ = 13.3 μg/mL), P. grisea (EC₅₀ = 14.4 μg/mL) and A. alternate (EC₅₀ = 15.6 μg/mL), superior to azoxystrobin, a commercial agricultural fungicide. The structure-activity relationship (SAR) revealed that the aniline moiety at position 4 of the quinoline scaffold played a key role in the potency of a compound. And the substitution positions of the aniline moiety significantly influenced the activities. These encouraging results yielded a variety of 2-phenylquinolines bearing an aniline moiety acting as promising antifungal agents.

N-Benzylanilines as Fatty Acid Synthesis Inhibitors against Biofilm-related Methicillin-resistant Staphylococcus aureus

Bacterial fatty acid synthase system is a well validated target for the development of novel antimicrobial agents. This study reports the synthesis of Schiff bases and their reductive N-benzylanilines. Most N-benzylanilines were active against Gram-positive bacteria, among which compound 4k performed best against both S. aureus and MRSA with the MIC value at 0.5 mg/L. Moreover, we identified the strong antibacterial activity for compound 4k against 19 clinical MRSA strains isolated from different specimen, which indicated its potential in clinical application. In vitro biofilm inhibition and microscopy assay revealed compound 4k inhibits biofilm formation and eradicates preformed biofilm effectively. The size-exclusion chromatography and docking study indicated that compound 4k mimics the binding mode of triclosan with saFabI. The efficiency of the protein-inhibitor interaction was evaluated by measuring NADPH reduction using trans-2-octenoyl-CoA as substrate. Overall, our data demonstrate that N-benzylaniline is a promising scaffold for anti-staphylococcal drug development.