Augmentation of the antibacterial activity of magainin by positive-charge chain extension

Novel analogs of the broad-spectrum antimicrobial peptide magainin-2 were obtained by extension of its chain through addition of segments of positively charged amino acids to either its N or its C terminus and by increasing its helicity. The activity of magainin-2 toward American Type Culture Collection strains of Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus was most considerably enhanced by these modifications, whereas, in general, its low hemolytic capacity was not or was only slightly affected. The antibacterial potencies of magainin-2 and its derivatives were more evident following decreases of pH from 7.2 to 6 and 5.