Table 2.

Antimicrobial activities of the Pro9 series peptides against gram-negative bacterial strains and multidrug-resistant (MDR) bacterial strains.

Microorganisms	Minimal inhibitory concentration (MIC) in μM
	Pro9-3	Pro9-3D	Pro9-3-K	Pro9-3D-K	Melittin
Gram-negative bacteria
E. coli	16	8	64	16	8
A. baumannii	16	4	64	32	8
MDR Gram-negative bacteria
MDREC 1229	16	8	64	32	16
MDREC 1238	32	4	64	16	32
MDRAB 12010	16	8	64	32	8
MDRAB 12220	16	8	64	32	8
aGM	20	6.4	64	28.8	14.4
bHC10	200	200	200	200	0.8
cRelative selective index	10	31.25	3.125	6.94	0.06

^aThe geometric means (GM) are the average values of minimum inhibitory concentration (MIC) values of all tested bacterial strains.

^bHC₁₀ is the peptide concentration which induces 10% hemolysis of sheep red blood cells in vitro.

^cWhen no detectable hemolysis was observed at 100 μM, a value of 200 μM was used to calculate the relative selective index. The relative selective index was calculated using HC₁₀/GM of the MIC (μM). The peptides with larger values indicate greater cell selectivity.