Table 1.
Net charge, minimal inhibitory concentration (MIC), 50% hemolytic concentration, and cell selectivity index of small lipopeptides
| Group | Peptide | Net Charge |
MIC (μM) | HL50 # | CSI* | |||
|---|---|---|---|---|---|---|---|---|
| SA§ | PA | EC | KP | |||||
| I | C14-KK | 2 | 6.25 | 50 | 3.1 | >50 | 50 | 8 |
| C14-RRR | 3 | 1.56 | >50 | 3.1 | >50 | 42 | 27 | |
| II | C14-LK | 1 | 1.56 | >50 | 3.1 | 6.2-12.5 | <<12.5 | <<8 |
| C14-RW | 1 | 3.1 | >50 | >50 | >50 | <<12.5 | <<4 | |
| C14-WR | 1 | 3.1 | >50 | >50 | >50 | 19 | 6.1 | |
| C14-WWK | 1 | 25 | >50 | >50 | >50 | <<12.5 | <<0.5 | |
| C14-KWI | 1 | 3.1 | >50 | >50 | >50 | <<12.5 | <<4 | |
| C14-LKW | 1 | 6.25 | > 50 | > 50 | > 50 | <<12.5 | <<2 | |
| C14-LKK | 2 | 1.56 | 3.1 | 3.1 | >50 | <<12.5 | <<8 | |
| C14-LLK | 1 | >50 | >50 | >50 | >50 | ND | ND | |
| III | C14-EE | −2 | >50 | >50 | >50 | >50 | >>100 | ND |
| C14-LE | −1 | >50 | >50 | >50 | >50 | >>100 | ND | |
| C14-WE | −1 | >50 | >50 | >50 | >50 | >>100 | ND | |
| C14-EW | −1 | >50 | >50 | >50 | >50 | >>100 | ND | |
| C14-LWE | −1 | > 50 | > 50 | > 50 | > 50 | >>100 | ND | |
| Antibiotics | Daptomycin | −3 | 0.78 | ND | ND | ND | ND | ND |
| Vancomycin | 0 | 0.78 | > 25 | > 25 | > 25 | ND | ND | |
§
SA: Staphylococcus aureus USA300; PA: Pseudomonas aeruginosa PAO1; EC: Escherichia coli 25922; KP: Klebsiella pneumoniae
#
HL50 is the hemolytic concentration of the peptide required to lyse 50% of hRBCs (2% v/V); << indicates over 80 % of the hemolysis at this concentration or lower; >> indicates less than 20 % of hemolysis at this concentration or higher
*
CSI refers to the cell selectivity index; calculated using the ratio of HL50/MIC for S. aureus USA300. The antibacterial assay of the group III anionic peptides was done in the presence or absence of 2 mM Ca2+.
ND: not determined.