In vitro antimicrobial activities of novel quinoline compounds

Pao Yue-kong Library Electronic Theses Database

In vitro antimicrobial activities of novel quinoline compounds

 

Author: Fong, Ka Yin
Title: In vitro antimicrobial activities of novel quinoline compounds
Degree: M.Sc.
Year: 2012
Subject: Quinoline.
Anti-infective agents.
Hong Kong Polytechnic University -- Dissertations
Department: Dept. of Health Technology and Informatics
Pages: 146 p. : ill. ; 30 cm.
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b2523630
URI: http://theses.lib.polyu.edu.hk/handle/200/6631
Abstract: The newly synthesized quinoline derivatives were under investigation for their antimicrobial effects against different micro-organisms. Three groups of compounds, groups A, B and C, with differences in the branching and molecular sizes were included. These compounds were previously tested against hepatocellular cancer cells and showed in vitro cytotoxicity. In this study, the compounds were tested against bacterial and fungal species for their antimicrobial effects. The minimum inhibition concentration (MIC) of each quinoline derivatives was found with the serial dilution method in a microtitre plate. Time-kill analyses were used to analyze the inhibition rate and mode of action of compounds against micro-organisms. Electron microscopy was used to investigate the effect of the compounds to the structural change of the micro-organisms. It could be found that group A compounds having low molecular size had more compounds exhibited antimicrobial effects. There were five group A compounds exhibited inhibitory effect against Strep. pneumoniae at relatively lower concentration. Moreover, two of them, Q021 and Q033, showed inhibition on two or more microorganisms. For group B compound (except Q116a) and group C compounds, which had a high molecular size, could not exhibit antimicrobial effect at high concentrations. However, one of the group B compound, Q116a, was the only compound exhibited inhibition against C. albicans at a relatively low concentration in this project. From the time-kill analysis, Q021 and Q033 showed bactericidal effects against S. aureus and Strep. pneumoniae with the minimum inhibition concentration (MIC). Q033 and Q116a showed bacteriostatic effects against C. albicans with MIC. The micrograph showed that the quinoline compounds caused a structural change in intracellular content and cell wall. As the novel quinoline compounds had similar structure to quinolone antibiotics, further investigation could be done to confirm if the target of quinoline compounds is the same as quinolone antibiotics. Abnormal dividing microbial cells in micrograph could be observed and it proposed that the target could be topoisomerase II which controls chromosome separation. Structures of Q021, Q033 and Q116a provided information for further development of antimicrobial agents. In addition, these quinoline compounds could be used as disinfectant and additives in selective medium for micro-organisms.

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