Synthesis, Characterization and Antimicrobial Activity of Some Novel Quinoline Derivatives Bearing Pyrazole and Pyridine Moieties

Abstract

our efforts were directed towards the synthesis of new heterocyclic compounds containing quinoline ring bearing pyrazole and pyridine moieties with anticipated biological activities. Experimental General All melting points were determined in openglass capillaries and are uncorrected. IR spectra were recorded on a Bruker Vector 22 Germany spectrometer (KBr). 1 HNMR spectra were recorded on Bruker 400 MHz spectrometer using TMS as an internal reference. The Electron Impact mass spectrometry was obtained at 70 eV using Shimadzu QP-2010 Plus mass spectrometer. The reactions were monitored by thin-layer chromatography (TLC) on silica gel F254 aluminum sheets (Merck), and the spots were visualized by UV lamp at 254-365 nm. I N continuation of our interest in synthesis of novel quinoline derivatives with anticipated biological activity, we have synthesized new quinoline derivatives bearing pyrazole and pyridine moieties by formylation of quinoline hydrazones through the Vilsmeier-Haack reaction which is a common method for the synthesis of 4-formyl pyrazoles. Condensation of 2-hydrazinylquinoline 1 with 4-substituted acetophenone gave the corresponding hydrazones 2a-c which in turn underwent the Vilsmeier-Haack reaction in POCl 3 /DMF to furnish the corresponding 4-formyl pyrazole derivatives 3a-c. One-pot reaction of compounds 3a-c with malononitrile and thiophenol or ethyl mercaptan gave the 3,5-pyridine dicarbonitrile derivatives 11a-f. The synthesized derivatives were screened for their antimicrobial activities against Gram negative bacteria, Gram positive bacteria and Fungi. Most of compounds showed excellent antimicrobial activities compared to the reference drugs. All the newly synthesized compounds have been characterized by means of elemental analyses, IR, 1 H NMR and MS.

Recent advances in functionalized quinoline scaffolds and hybrids—Exceptional pharmacophore in therapeutic medicine

“…All derivatives 14a-f were reported to exhibit broader antimicrobial activities when compared to standards. The hybrids were yellow in color with melting points between (160-200) o C and others greater than 250 °C (Mahgoub, 2018).…”

“…Some of the synthesized derivatives, such as 15, displayed far broader antibacterial activity than Ciprofloxacin, while others demonstrated good to moderate antimicrobial performance against the pathogens examined. These compounds were found to have antibacterial activity against a variety of bacteria (Mahgoub, 2018).…”

Antimicrobial and antiproliferative activities of novel synthesized 6‐(quinolin‐2‐ylthio) pyridine derivatives with molecular docking study as multi‐targeted JAK2/STAT3 inhibitors

“…Previous literature reported that quinoline-2-thiones have a variety of applications such as synthetic intermediates (Jinbo et al, 1993;Joseph et al, 2002), bioactive molecules (Xavier, 1958), sulfur-nitrogen mixed donor ligands (Leeaphon et al, 1995;Nakano et al, 1977;Zhang & Matteucci, 1999), protective groups of thiols (Nakamura et al, (2002); Prabhu et al, 2008), and corrosion inhibitors (O'Connor & Lَ pez et al, 2014), as well as fluorescent sensors for metals, pH, and HNO (Albert & Barlin, 1959). Since pyridinedicarbonitrile nucleus is among the most widely used biologically and therapeutically important agents, this encourages us to attach it to quinoline ring system aiming to obtain novel compounds with anticipated biological activity (Amer El-Eraky et al, 2018;Amer Ramses et al, 2018). Kambe et al (1980) reported that the reaction of malononitrile with aromatic aldehyde and alkyl ketones in the presence of ammonium acetate and boiling benzene yields 2-Amino-4-aryl-3-cyanopyridines, and the reaction was assumed to proceed by formation of arylidenemalononitrile firstly which in turn reacts with alkyl ketones.…”

Identification of naphthyridine and quinoline derivatives as potential Nsp16-Nsp10 inhibitors: a pharmacoinformatics study

“…It is reported that naphthyridine scaffold containing molecules have shown a wider range of biological activities including antiviral, antimicrobial, anticancer, antiinflammatory and analgesic (Singh et al, 2017). Similarly, quinoline is belonged to the class of nitrogen heterocyclic compounds and possess anti-malarial, anti-inflammatory, antibacterial, anticancer, anti-microbial, anthelmintic and anti-fungal types of biological activities (Amer et al, 2018;Cocco et al, 2000;Mukherjee et al, 2001;Narender et al, 2005). For instance, the 1,8-naphthyridine and quinoline (Saleh et al, 2020) represent a core for several vital drugs included Gemiflloxacin (antimicrobial) (Marchese et al, 2000) and anticonvulsants (Leonard et al, 2002).…”