• Journal of Microbiology
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• v.39 no.1
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• pp.62-66
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• 2001

Unlike eukaryotic efflux pumps energized by ATPase bacterial efflux pumps are energized by the proton motive force. That is the reason why CCCP, an inhibitor of proton motive forcer is widely used to study the bacterial efflux pump. In many cases, efflux systems have been observed only in quinolone-resistant bacteria. Most of the quinolone-susceptible strains have been found to maintain little efflux pump. However some susceptible bacteria skewed the increased intracellular quinolone concentration only at a low concentration (0.01 or 0.1 mM) but net at a high concentration (1 mM) of CCCP. If bacterial cells were killed at high concentrations of CCCP and lost the integrity of their membranes, the intracellular quinolone would leak out from cells with no efflux system. The efflux pump system in the quinolone-susceptible strains could net be detected at the same concentration used for resistant bacteria. To test this hypothesist the intracellular quinolone concentration in the quinolone-susceptible and -resistant strains of Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus was assayed at various concentrations of CCCP. Since the effect of CCCP is very rapid, the survival of bacteria was observed by assaying the DNA synthesis in 5 min. In the case of E. coli, but not P. aeruginosa or S. aureus, the quinolone susceptible strain was more susceptible to CCCP than the quinolone resistant ones, especially when the incubation with CCCP was extended. Decrease of the intracellular quinolone concentration resulted in a false result-no or weak efflux system in the quinolone susceptible strains. Results suggested that the concentration of CCCP should be optimized in order to detect the efflux system in the quinolone susceptible strains of E. coli.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1994.04a
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• pp.221-221
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• 1994

The cross-coupling reaction of organo tin reagents with a variety of organic halides, catalyzed by palladium, provides a novel method for generating a carbon-carbon bond. We use this method for antibacterial agents, and synthesis of new quinolone derivatives which have carbon-carbon bond at C-7 position of general quinolone moieties. Aryl tin, quinolone moieties, and palladium catalyst were refluxed in DMF to afford new quinolone derivatives. This palladium catalyzed coupling reactions have capacity for further synthetic elaboration.

• YAKHAK HOEJI
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• v.37 no.6
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• pp.615-620
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• 1993

The cross-coupling reaction of organo tin reagents with a variety of organic halides, catalyzed by palladium, provides a novel method for generating a carbon-carbon bond. We used this method for the antibacterial agents, and synthesis of new quinolone derivatives which have carbon-carbon bond at C-7 position of general quinolone moieties. Aryl tin, quinolone moieties, and palladium catalyst were refluxed in DMF to afford new quinolone derivatives. This palladium catalyzed coupling reactions have capacity for further synthetic elaboration.

• Korean Journal of Pharmacognosy
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• v.49 no.2
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• pp.108-112
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• 2018

Four quinolone alkaloids, 2-heptyl-4-quinolone (1), 2-nonyl-4-quinolone (2), 2-undecyl-4-quinolone (3), and 2-undecen-1'-yl-4-quinolone (4), together with two nitrogen derived benzoic acid derivatives, N-acetylanthranilic acid (5) and o-acetamidobenzamide (6) have been isolated from the Arctic bacterial strain, Pseudomonas aeruginosa. The structures of the compounds were determined by 1D and 2D NMR, and MS experiments, as well as by comparison of their data with published values. To the best of our knowledge, compounds 3-6 were isolated for the first time from P. aeruginosa.

• Bulletin of the Korean Chemical Society
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• v.17 no.1
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• pp.90-93
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• 1996

• Korean Journal of Microbiology
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• v.50 no.3
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• pp.185-190
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• 2014

The aim of this study was to investigate the prevalence of quinolone resistant E. coli from raw bulk milk and to characterize the resistance determinants. In this study, the gyrA, gyrB, parC, and parE quinolone resistance determining regions (QRDR) were sequenced from quinolone resistant E. coli isolates. Also, the presence of plasmid-mediated quinolone resistance (PMQR) and the expression of efflux pump genes based on quantitative real-time PCR (qRT-PCR) were investigated. Of the 487 coliform bacteria, 9 strains showed nalidixic acid resistance, and 6 of the 9 nalidixic acid resistant isolates were also ciprofloxacin resistant. These 9 strains had a single mutation at codon 83 (S83L) in gyrA, 2 of them had double mutations at codon 83 and 87 (S83L and D87N) in gyrA and 3 of the 9 isolates had single mutations at codon 80 (S80I) in parC. None of the 9 isolates harbored PMQR determinants. Compared with wild-type E. coli ATCC 25922, an over-expression of the acrB gene (2.15-5.74 fold), encoding the pump component of the AcrAB-TolC efflux pump was observed in 4 of 6 ciprofloxacin resistant isolates. This study identified the quinolone resistance mechanism of E. coli isolated from raw milk samples in Gyeonggi-do.

• Archives of Pharmacal Research
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• v.29 no.5
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• pp.369-374
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• 2006

An efficient method for the synthesis of optically active 2-substituted 2,3-dihydro-4-quinolones has been developed. The key features include the introduction of a chiral side chain and the construction of quinolone skeleton by Mitsunobu alkylation and hydroarylation, respectively.

• YAKHAK HOEJI
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• v.47 no.5
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• pp.283-287
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• 2003

Isoflavonoids are abundant in natural products and reported with many synthetic variations. However, relatively few quinolone analogs of isoflavonoids have been described. As part of our endeavor to pursue biologically active novel isoflavonoids, we report an efficient synthetic route for quinolone analogs of isoflavonoids. The key intermediate, 2'-aminochalcone 2 was obtained from substituted aniline and cyclized to afford quinolones 6, 8a, and 8b.

• Korean Journal of Clinical Laboratory Science
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• v.50 no.4
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• pp.422-430
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• 2018

The inappropriate and widespread use of quinolones in humans and animals may cause accelerated emergence and spread of antimicrobial-resistant determinants. In this study, we investigated quinolone resistance mechanisms in a total of 65 nalidixic acid-resistant E. coli isolated from swine rectal swabs (N=40) and clinical specimens (N=25). Antimicrobial susceptibilities were determined by the disk diffusion method. PCR and DNA sequencing were performed for investigations of genes and mutations associated with quinolone resistance. In our study, 62 of 65 nalidixic acid-resistant E. coli harbored mutations in gyrA, parC, and/or parE genes; of the 65 isolates, 62 (95.4%) had mutations in the gyrA gene, 35 (53.8%) had mutations in the parC gene, 7 (10.8%) had mutations in the parE gene. The 35 isolates harbored mutations in two genes, gyrA and parC. Plasmid-mediated quinolone resistance (PMQR) determinants were investigated in the 65 isolates. Thirteen of 65 nalidixic acid-resistant E. coli contained the qnrS gene and 10 of those isolates had mutations in the gyrA, parC, and/or parE genes. We confirmed that an important mechanism of quinolone resistance in E. coli isolated from human and swine involves chromosomal mutations in the gyrA, parC, and/or parE genes with increasing use of quinolone for treatment or additives.

• Biomolecules & Therapeutics
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• v.7 no.2
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• pp.164-169
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• 1999

The synthesis and antimicrobial activity of N-substituted glycol derivatives of Norfloxacin were described. Norfloxacin was treated with chloroacetyl chloride to yield chloroacetyl norfloxacin (1). This compounds was reacted with alkyldiamines to afford bivalent ligand quinolone carboxylic acids (2-6), which was added to pivaloyloxymethyl chloride to give bivalent ligand pivaloyloxymethyl quinolone carboxylates (7-11). Chloroacetyl norfloxacin (1) treated with alkylamines to obtain monovalent ligand quinolone carboxylic acids (12-15), which was reacted with pivaloyloxymethyl chloride to get monovalent ligand pivaloyloxymethyl quinolone carboxylates (16-19). Free carboxylic quinolones (2-6, 12-15) showed little stronger activities to their pivaloyloxymethyl esters (7-11, 16-19). In monovalent ligand quinolone analogues, longer a1kyl chain com-pounds showed stronger activities than shorter one.