Table 1.

Antibacterial and antiendotoxic activities of the peptides and their N-acyl derived Lipopeptides

Compound	Sequence1	MIC (μg/mL) of compound on the indicated bacterial strain
		Ec	Ec-2	Pa	Pa-2	Ab	Sm	Bb	Ba	Sa
P2-15	F W R I R I R R -NH2	8	8	32	16	128	64	2	64	32
LP3-55	octanoil-P2-15	32	16	64	64	64	256	8	8	16
LP3-56	2-etilhexanoil-P2-15	16	8	32	64	64	128	8	8	16
LP3-57	2,2-dimetilbutanoil-P2-15	8	8	32	8	64	128	4	8	8
LP3-58	6-metiloctanoil-P2-15	32	16	64	256	64	256	16	8	64
LP3-79	diciclohexilacetil-P2-15	32	64	256	64	256	>256	8	8	32
P2-27	F W R R F W R R -NH2	16	64	64	32	128	256	4	16	16
LP3-60	octanoil-P2-27	64	128	128	128	256	256	8	8	128
LP3-63	6-metiloctanoil-P2-27	64	64	256	128	256	128	8	16	16
P2-29	F W R I W R W R -NH2	16	16	32	8	32	128	4	16	8
P2-33	P F W R I R I R R -NH2	16	64	64	32	128	256	4	16	16
LP3-53	octanoil-P2-33	64	128	128	128	256	256	8	8	128

¹Parent peptides and their N-acyl derivatives were synthesized with an amidated C-terminus

²Minimum inhibitory concentration of the compound determined by a microbroth-based assay in Mueller-Hinton medium. Abbreviations: Ec, Escherichia coli ATCC 25922; Ec-2; Escherichia coli DC2; Pa, Pseudomonas aeruginosa 4158-02 CUN; Pa-2, Pseudomonas aeruginosa ATCC 27853; Ab, Acinetobacter baumannii ATCC 19606; Sm, Stenotrophomonas maltophilia 3998-00 CUN; Bb, Bordetella bronchiseptica 11844-99 CUN; Ba, Brucella abortus 9,49 perA; Sa, Staphylococcus aureus ATCC 25923; MRSA, Staphylococcus aureus ATCC 43300 (MRSA)

³novobiocin enhancing activity of peptides on Pseudomonas aeruginosa Ps4 expressed as Fractional Inhibitory Concentration (FIC) index. FIC index was calculated according to the following formula: [(A) /MIC_A] + [(P) /MIC_P]= FIC_A + FIC_P = FIC index, where MIC_A and MIC_P are the MICs of the antibiotic and peptide determined separately, and (A) and (P) are the MICs of the antibiotic and peptide when determined in combination

⁴number on the left: percentage of killing by the compound (MTT test; 4 h of treatment) when the peptide was added at 10 times its MIC on a biofilm of Pseudomonas aeruginosa PAO1; number on the right: percentage of biofilm removal determined by crystal violet staining under the same conditions of the killing assay. Values of standard deviation were always below 11%. n.d. not determined

⁵survival of CD-1 mice after 7 days of being inoculated intraperitoneally (i.p) with 0.3 μg of lipopolysaccharide from Pseudomonas aeruginosa PAO1 followed 1 min later by the compound (150 μg, i.p.); galactosamine (18 mg) was co-inoculated with the lipopolysaccharide to sensitize the animals to endotoxin. −, +, ++, +++ denotes the level of protection (null, low, intermediate, high, respectively) afforded by the compound with respect to a control group of animals receiving no treatment