Biphenyl inhibitors with further biological evaluation reported. IC₅₀ values were the mean of 2 or 3 different experiments. Error limits are not given, as the gel-based assays used are at best semi-quantitative.

Compound	R	Ring chirality	E. coli DNA gyrase IC50 (μM)	E. coli topo IV IC50 (μM)	E. coli K12 MG1655 MIC (μg mL−1)	S. aureus NCIMB 50080 MIC (μg mL−1)	E. coli K12 MG1655 S83L MIC (μg mL−1)
Ciprofloxacinb			0.6	5.7	0.016	0.5	0.5
1	Thiophene		0.3a	>540a	8a	8a	N.D.
5		(R)	21	>100	32	16	32
6		(R)	12	>100	64	32	64
7		(R)	17	64	32	16	32
11		(R)	73	94	>128	>128	>128
31		Racemic (3-OH)	41	>100	>128	128	>128

^aData from ref. 14 which used different E. coli and S. aureus bacterial strains.

^bCiprofloxacin used as a standard control.