In vitro antibacterial activity of selected compounds against Gram-positive streptococci strains.

Compd	R1	R2	X	MICa (μg mL−1)
				S. pneumoniae B0652 (eryS)	S. pneumoniae B0326 (M)	S. pyogenes B0542 (eryS)	S. pyogenes B0545 (M)
12a	H		NH	128	>128	16	8
12c	OCH3		NH	32	128	16	8
15a	H		NH	16	32	2	2
15b	F		NH	64	64	4	4
15c	OCH3		NH	32	64	2	4
16a	H		NH	32	64	4	4
16c	OCH3		NH	64	64	4	4
17a	H		NH	8	32	4	4
18a	H		NH	128	128	8	8
18c	OCH3		NH	>128	128	16	16
21b	F		S	32	128	32	128
AZM b				0.125	16	0.125	8
Ampicillin				0.25	0.25	0.25	0.25

^aMinimal inhibitory concentrations.

^bAzithromycin.