In Vitro Bactericidal Activity of 4- and 5-Chloro-2-hydroxy-N-[1-oxo-1-(phenylamino)alkan-2-yl]benzamides against MRSA

Table 1

Chemical structures and in vitro MIC and MBC µg/mL values of tested 5- and 4-chloro-2-hydroxy-N-[1-oxo-1-(phenylamino)alkan-2-yl]benzamides (bactericidal effect of individual compounds against particular strains marked in bold).

Comp.	R^1	R^2	R^3	MIC [µg/mL]				MBC [µg/mL]
				1	2	3	4	1	2	3	4
1a	5-Cl	4-CH3	(S)-CH3	>256	>256	>256	>256	>256	>256	>256	>256
1b	5-Cl	4-CH3	(S)-CH(CH3)2	>256	>256	32	32	>256	>256	128	>256
1c	5-Cl	4-CH3	(S)-benzyl	>256	>256	>256	>256	>256	>256	>256	>256
1d	5-Cl	4-CH3	(R)-CH2-indolyl	>256	>256	>256	>256	>256	>256	>256	>256
1e	5-Cl	4-OCH3	(S)-CH(CH3)2	>256	>256	>256	>256	>256	>256	>256	>256
1f	5-Cl	4-CF3	(S)-CH(CH3)2	4	2	2	2	4	4	8	4
1g	4-Cl	4-Br	(S)-CH(CH3)2	8	4	4	4	16	8	8	8
1h	4-Cl	3,4-Cl	(S)-CH(CH3)2	2	1	1	1	4	1	4	2
1i	4-Cl	3,4-Cl	(S)-benzyl	1	1	0.5	0.5	8	1	8	1
AMP	—	—	—	>16	>16	>16	0.25	>16	>16	>16	0.25
CPX	—	—	—	>16	>16	>16	0.5	>16	>16	>16	0.5
VAN	—	—	—	2	1	1	1	2	1	1	1

Staphylococcal strains: 1: MRSA 63718; 2: MRSA SA 630; 3: MRSA SA 3202; 4: Staphylococcus aureus ATCC 29213.
AMP: ampicillin; CPX: ciprofloxacin; VAN: vancomycin.
MIC breakpoints for S. aureus ATCC 29213 [µg/mL]: AMP > 2, CPX > 1, VAN > 2 [23–25].