Microwave-irradiated synthesis and antimicrobial activity of 2-phenyl-7-substitutedalkyl/arylaminoquinoline-4-carboxylic acid derivatives

Ionically Tagged Magnetic Nanoparticles with Urea Linkers: Application for Preparation of 2-Aryl-quinoline-4-carboxylic Acids via an Anomeric-Based Oxidation Mechanism

In this exploration, we reported the design and synthesis of a novel ionically tagged magnetic nanoparticles bearing urea linkers, namely, Fe₃O₄@SiO₂@(CH₂)₃-urea-thiazole sulfonic acid chloride. The structure of the mentioned compound was fully characterized by using several techniques including Fourier transform infrared spectroscopy, energy-dispersive X-ray analysis, elemental mapping analysis, thermogravimetric analysis/differential thermal analysis, scanning electron microscopy, transmission electron microscopy, and vibrating sample magnetometer. In the presence of the novel reusable catalyst, applied starting materials including aryl aldehydes, pyruvic acid, and 1-naphthylamine condensed to afford the desired 2-aryl-quinoline-4-carboxylic acid derivatives via an anomeric-based oxidation pathway under solvent-free conditions.

Design, Synthesis and Antibacterial Evaluation of Some New 2-Phenyl-quinoline-4-carboxylic Acid Derivatives

A series of new 2-phenyl-quinoline-4-carboxylic acid derivatives was synthesized starting from aniline, 2-nitrobenzaldehyde, pyruvic acid followed by Doebner reaction, amidation, reduction, acylation and amination. All of the newly-synthesized compounds were characterized by ¹H-NMR, ¹³C-NMR and HRMS. The antibacterial activities of these compounds against Gram-negative (Escherichia coli, Pseudomonas aeruginosa) and Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis), as well as one strain of methicillin-resistant Staphylococcus aureus (MRSA) bacteria were evaluated by the agar diffusion method (zone of inhibition) and a broth dilution method (minimum inhibitory concentration (MIC)), and their structure-activity relationships were obtained and discussed. The results revealed that some compounds displayed good antibacterial activity against Staphylococcus aureus, and Compounds 5a₄ and 5a₇ showed the best inhibition with an MIC value of 64 μg/mL against Staphylococcus aureus and with an MIC value of 128 μg/mL against Escherichia coli, respectively. The results of the MTT assay illustrated the low cytotoxicity of Compound 5a₄.