Article Sidebar
Published:
Jun 2, 2017Keywords:
Article Details
Submission of a manuscript to this journal is a representation that the manuscript has not been published previously and is not under consideration for publication elsewhere.
All authors named in each manuscript would be required to sign a form (to be supplied by the Editor) so that they may retain their copyright in the article but to assign to us (the Publishers) and its licensees in perpetuity, in all forms, formats and media (whether known or created in the future) to (i) publish, reproduce, distribute, display and store the contribution, (ii) translate the contribution into other languages, create adaptations, reprints, include within collections and create summaries, extracts and/or abstracts of the contribution, (iii) create any other derivative works(s) based on the contribution, (iv) to exploit all subsidiary rights in the contribution, (v) the inclusion of electronic links from the contribution to third party material where-ever it may be located, and (vi) license any thrid party to do any or all of the above.
Main Article Content
Synthesis of some quinoline-pyrazoline-based naphthalenyl thiazole derivatives and their evaluation as potential antimicrobial agents
Abstract
Purpose: To prepare and evaluate some quinoline-pyrazoline-based naphthalenyl thiazole derivatives as antimicrobial agents.
Methods: Some quinoline-pyrazoline-based naphthalenyl thiazoles (5a-5e and 6a-6e) were prepared by reacting 5-(2-chloroquinolin-3-yl)-3-substitutedphenyl-4,5-dihydro-1H-pyrazole-1-carbothiamides (4a- 4e) with 2-bromo-1-(1-naphthyl)ethanone and 2-bromo-1-(2-naphthyl)ethanone, respectively. Fourier transform infra-red (FTIR), 13C-Nuclear magnetic resonance (13C-NMR), 1H-Nuclear magnetic resonance (1H-NMR), elemental analysis, and mass spectrometry were used to elucidate and confirm the chemical structures of the target compounds. Serial plate dilution technique was used to evaluate the antimicrobial activity of the title compounds using ketoconazole and ofloxacin as standards, and their minimum inhibitory concentrations (MIC) were determined.
Results: A total of ten compounds, (5a-5e) & (6a-6e) were prepared. Compound 6d (R = 4-F, naphthalen-2-yl derivative) exhibited antimicrobial activities that were higher than those of the standard drug (ofloxacin) against S. aureus (MIC = 25 μg/mL, p < 0.05), S. epidermidis (MIC = 25 μg/mL, p < 0.0001), K. pneumonia (MIC = 25 μg/mL, p < 0.0001), P. vulgaris (MIC = 25 μg/mL, p < 0.0001) and P.
citrinum (MIC = 25 μg/mL, p < 0.0001). Compound 5d (R = 4-F, naphthalen-1-yl derivative) displayed higher antifungal activity than ketoconazole against C. albicans (MIC = 25 μg/mL, p <0.0001).
Conclusion: The naphthalen-2-yl derivatives (6a-6e) are superior antimicrobial agents as compared to the naphthalen-1-yl derivatives (5a-5e) and the presence of 4-F substituent in 6d and 5d is essential for stronger antimicrobial activity. The compound 6d needs further investigations related to its safety and efficacy.
Keywords: Quinoline, Pyrazoline, Thiazole, Antibacterial, Antifungal, Structure-activity relationship
