TABLE 1.

Inhibitory activities of quinolones against type II topoisomerases

Quinolone	Activity (μg/ml) against:
	S. aureus MS5935 topoisomerase IV		E. coli NIHJ JC-2 DNA gyrase		HeLa cell topoisomerase II
	IC50	MIC	IC50	MIC	IC50	Cytotoxicity
Gatifloxacin	13.8	0.05	0.109	0.0063	265	122
Clinafloxacin	3.23	0.025	0.045	0.0032	29.7	60.1
Ciprofloxacin	11.8	0.39	0.072	0.0032	34.4a	105
Sparfloxacin	22.3	0.05	0.130	0.0125	102	72.5
Ofloxacin	35.7	0.39	0.211	0.0125	132a	301
Tosufloxacin	NDb	ND	0.165	0.0125	ND	ND
Levofloxacin	19.9	0.20	0.186	0.0063	ND	ND
Lomefloxacin	35.2	0.39	0.171	0.025	238	216
Norfloxacin	26.0	0.78	0.309	0.025	87.3a	139
Fleroxacin	45.7	0.39	0.378	0.025	193a	349
Enoxacin	55.4	0.78	0.482	0.05	81.8	67.9
Pipemidic acid	350	25	3.18	0.78	ND	ND
Nalidixic acid	435	25	7.25	0.78	169a	277

^aData from previous study (25). 

^bND, not determined.