Synthesis and antimicrobial activity of novel quinoline derivatives bearing pyrazoline and pyridine analogues

The present investigation is in the interest of some synthesized novel derivatives containing (5-(2-chloroquinolin-3-yl)-3-(aryl)-4,5-dihydro-1H-pyrazol-1-yl)(pyridin-4-yl)methanones (4a-o) moieties incorporated with different biological active heterocycles such as quinoline, pyrazoline and pyridine derivatives. For the determination of the compounds reported in this paper was based on IR, H-1 NMR, C-13 NMR and mass spectral data and same compounds were screened for their antibacterial and antifungal activity on four bacteria (Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli, Pseudomonas aeruginosa) and three fungi (Candida albicans, Aspergillus niger, Aspergillus clavatus) using ampicillin and griseofulvin as the standard drugs. Cytotoxicity study was carried out using MTT colorimetric assay (HeLa cell line). Among the screened compounds, 4e, 4f and 4n showed most potent antibacterial activity, while compounds 4d and 4g emerged as the most active against fungal strains. The results demonstrated that compound 4o was remarkably active against all microbial strains. From the viewpoint of SAR studies, it was observed that the presence of electron withdrawing groups remarkably enhanced the antimicrobial activity of synthesized compounds. Additionally, preliminary MTT cytotoxicity studies on HeLa cells suggested that effective antimicrobial activity of 4e-g, 4n and 4o was accompanied by low cytotoxicity.