Mutually Isomeric 2- and 4-(3-nitro-1,2,4-triazol-1-yl)pyrimidines Inspired by an Antimycobacterial Screening Hit: Synthesis and Biological Activity against the ESKAPE Panel of Pathogens

Molecular Periphery Design Allows Control of the New Nitrofurans Antimicrobial Selectivity

A series of 13 new 3-substituted 5-(5-nitro-2-furyl)-1,2,4-oxadiazoles was synthesized from different aminonitriles. All compounds were screened in the disc diffusion test at a 100 μg/mL concentration to determine the bacterial growth inhibition zone presence and diameter, and then the minimum inhibitory concentrations (MICs) were determined for the most active compounds by serial dilution. The compounds showed antibacterial activity against ESKAPE bacteria, predominantly suppressing the growth of 5 species out of the panel. Some compounds had similar or lower MICs against ESKAPE pathogens compared to ciprofloxacin, nitrofurantoin, and furazidin. In particular, 3-azetidin-3-yl-5-(5-nitro-2-furyl)-1,2,4-oxadiazole (2h) inhibited S. aureus at a concentration lower than all comparators. Compound 2e (5-(5-nitro-2-furyl)-3-[4-(pyrrolidin-3-yloxy)phenyl]-1,2,4-oxadiazole) was active against Gram-positive ESKAPE pathogens as well as M. tuberculosis. Differences in the molecular periphery led to high selectivity for the compounds. The induced-fit docking (IFD) modeling technique was applied to in silico research. Molecular docking results indicated the targeting of compounds against various nitrofuran-associated biological targets.

Novel 5-Nitrofuran-Tagged Imidazo-Fused Azines and Azoles Amenable by the Groebke–Blackburn–Bienaymé Multicomponent Reaction: Activity Profile against ESKAPE Pathogens and Mycobacteria

A chemically diverse set of 13 5-nitrofuran-tagged heterocyclic compounds has been prepared via the Groebke–Blackburn–Bienaymé multicomponent reaction. The testing of these compounds against the so-called ESKAPE panel of pathogens identified an apparent lead compound—N-cyclohexyl-2-(5-nitrofuran-2-yl)imidazo[1,2-a]pyridine-3-amine (4a)—which showed an excellent profile against Enterobacter cloacae, Staphylococcus aureus, Klebsiella pneumoniae, and Enterococcus faecalis (MIC 0.25, 0.06, 0.25 and 0.25 µg/mL, respectively). Its antibacterial profile and practically convenient synthesis warrant further pre-clinical development. Certain structure-activity relationships were established in the course of this study which were rationalized by the flexible docking experiments in silico. The assessment of antitubercular potential of the compounds synthesized against drug sensitive H37v strain of Mycobacterium tuberculosis revealed little potential of the imidazo-fused products of the Groebke–Blackburn–Bienaymé multicomponent reaction as chemotherapeutic agents against this pathogen.

Novel Hybrid 1,2,4- and 1,2,3-Triazoles Targeting Mycobacterium Tuberculosis Enoyl Acyl Carrier Protein Reductase (InhA): Design, Synthesis, and Molecular Docking

Tuberculosis (TB) caused by Mycobacterium tuberculosis is still a serious public health concern around the world. More treatment strategies or more specific molecular targets have been sought by researchers. One of the most important targets is M. tuberculosis' enoyl-acyl carrier protein reductase InhA which is considered a promising, well-studied target for anti-tuberculosis medication development. Our team has made it a goal to find new lead structures that could be useful in the creation of new antitubercular drugs. In this study, a new class of 1,2,3- and 1,2,4-triazole hybrid compounds was prepared. Click synthesis was used to afford 1,2,3-triazoles scaffold linked to 1,2,4-triazole by fixable mercaptomethylene linker. The new prepared compounds have been characterized by different spectroscopic tools. The designed compounds were tested in vitro against the InhA enzyme. At 10 nM, the inhibitors 5b, 5c, 7c, 7d, 7e, and 7f successfully and totally (100%) inhibited the InhA enzyme. The IC50 values were calculated using different concentrations. With IC50 values of 0.074 and 0.13 nM, 7c and 7e were the most promising InhA inhibitors. Furthermore, a molecular docking investigation was carried out to support antitubercular activity as well as to analyze the binding manner of the screened compounds with the target InhA enzyme's binding site.

Development and Research Progress of Anti-Drug Resistant Bacteria Drugs

Bacterial resistance has become increasingly serious because of the widespread use and abuse of antibiotics. In particular, the emergence of multidrug-resistant bacteria has posed a serious threat to human public health and attracted the attention of the World Health Organization (WHO) and the governments of various countries. Therefore, the establishment of measures against bacterial resistance and the discovery of new antibacterial drugs are increasingly urgent to better contain the emergence of bacterial resistance and provide a reference for the development of new antibacterial drugs. In this review, we discuss some antibiotic drugs that have been approved for clinical use and a partial summary of the meaningful research results of anti-drug resistant bacterial drugs in different fields, including the antibiotic drugs approved by the FDA from 2015 to 2020, the potential drugs against drug-resistant bacteria, the new molecules synthesized by chemical modification, combination therapy, drug repurposing, immunotherapy and other therapies.