CRAMP analog having potent antibiotic activity without hemolytic activity

CRAMP-18 is an 18-residue functional region, corresponding to residues 16-33 of a mouse-derived antibiotic peptide CRAMP. To develop novel antibiotic peptides possessing strong antibiotic activity against bacterial, fungal and tumor cells without hemolytic activity, three analogs of CRAMP-18 were synthesized containing either Leu- or Lys-substitution. Leu-substitution ([L^{1, 8}]-CRAMP-18) in the hydrophobic helix face of CRAMP-18 induced a dramatic increase in antibiotic activity without a significant increase in hemolytic activity. Lys-substitution ([K^{2, 13}]-CRAMP-18 or [K^{9, 16}]-CRAMP-18) in the hydrophilic helix face produced a smaller response. Therefore, [L^{1, 8}]-CRAMP-18 may be an attractive candidate for developing novel peptide antibiotics.