Bactericidal kinetics of 3 lactoferricins against Staphylococcus aureus and Escherichia coli

Bovine lactoferricin is an antimicrobial, cationic peptide generated upon g astric pepsin cleavage of bovine lactoferrin. We investigated the bacterici dal effects of native lactoferricin [Lfcin B(17-41)], a shortened derivativ e [Lfcin B(17-31)] and the all-D-amino acid counterpart of Min B(17-31) aga inst Escherichia coli and Staphylococcus aureus. The results revealed diffe rent activities for the peptides against Gram-positive and -negative bacter ia. D-Lfcin B(17-31) was the most efficient peptide against E. coli. The sa me peptide showed improved activity against S. aureus, D-Min B(17-31) showe d a significant better efficacy when compared to the L-form, but not when c ompared to Lfcin B(17-41). There was no correlation between the bactericida l concentrations and the time needed to achieve maximum effect. This indica tes the importance of structural differences between the peptides and/or ba cteria and implies that the simple thesis of 1 antibacterial target is not valid for lactoferricin.