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Novel 1-8-bridged chiral quinolones with activity against topoisomerase II: stereospecificity of the eukaryotic enzyme.
- Source :
-
Antimicrobial agents and chemotherapy [Antimicrob Agents Chemother] 1993 Apr; Vol. 37 (4), pp. 646-51. - Publication Year :
- 1993
-
Abstract
- A series of novel C-7 quinolyl-substituted enantiomers of ofloxacin were used to determine the stereospecificity of topoisomerase II for the C-11 methyl group in tricyclic quinolones. In all cases, the S isomer was the most active compound against the eukaryotic enzyme. It was approximately 2.2-fold more potent than the R isomer at inhibiting the overall catalytic activity of topoisomerase II (as monitored by DNA relaxation assays). A markedly greater difference in quinolone activity was observed in enzyme-mediated DNA cleavage reactions. While the S enantiomer stimulated nucleic acid breakage approximately 3.5-fold, the R compound did not enhance and, in fact, decreased initial DNA cleavage levels by approximately 50%. The activity of the racemic mixture more closely resembled that of the R enantiomer. In competition experiments, the DNA cleavage-enhancing effects of the S isomer were attenuated by the R compound. Taken together, these latter results indicate that the R enantiomer is an antagonist of S isomer-promoted topoisomerase II-mediated DNA cleavage. Finally, the cytotoxic potential of quinolyl-substituted ofloxacin analogs correlated with the ability to stimulate enzyme-mediated DNA cleavage. Thus, stereochemistry appears to be a governing factor for the potential development of tricyclic quinolones as topoisomerase II-targeted drugs with antineoplastic activity.
Details
- Language :
- English
- ISSN :
- 0066-4804
- Volume :
- 37
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- Antimicrobial agents and chemotherapy
- Publication Type :
- Academic Journal
- Accession number :
- 8388196
- Full Text :
- https://doi.org/10.1128/AAC.37.4.646