Antipathogenic synthetic peptides and compositions comprising them

A peptide selected from the group consisting of:

• (A) a non-natural synthetic peptide having from 6 to 12 amino acid residues or a non-natural synthetic cyclic peptide having from 6 to 14 amino acid residues and a net positive charge which is greater than +1, said peptide consisting of hydrophobic amino acid residues excepting glycine and tyrosine, and positively charged amino acid residues, wherein at least one but not all of such amino acid residues is a D-amino acid, said peptide having a ratio of hydrophobic to positively charged amino acids such that the peptide is cytolytic to pathogenic cells but does not cause cytolysis of red blood cells, and having a sequence of amino acids such that the same amino acid sequence in which each residue is in the L-configuration is not found in nature, and cyclic derivatives thereof having from 6 to 14 amino acid residues, with the proviso that said peptide is not that of SEQ ID NO:1, SEQ ID NO:12, SEQ ID NO:14, or SEQ ID NO:23;
• (B) a non-natural synthetic peptide having from 6 to 12 amino acid residues or a non-natural synthetic cyclic peptide having from 6 to 14 amino acid residues and a net positive charge which is greater than +1, said peptide consisting of hydrophobic amino acid residues excepting glycine and tyrosine, positively charged amino acid residues, and polar amino acid residues, wherein at least one but not all of such amino acid residues is a D-amino acid, said peptide having a ratio of hydrophobic to positively charged amino acids such that the peptide is cytolytic to pathogenic cells but does not cause cytolysis of red blood cells, and having a sequence of amino acids such that the same amino acid sequence in which each residue is in the L-configuration is not found in nature, and cyclic derivatives thereof having from 6 to 14 amino acid residues, with the proviso that said peptide is not that of SEQ ID NO:1, SEQ ID NO:12, SEQ ID NO:14, or SEQ ID NO:23;
• (C) a random copolymer having a net positive charge which is greater than +1, said random copolymer consisting of a hydrophobic L-amino acid, a positively charged L-amino acid and a D-amino acid in a ratio of hydrophobic to positively charged amino acids such that the copolymer is cytolytic to pathogenic cells but does not cause cytolysis of red blood cells;
• and
• (D) a mixture of a plurality of peptide diastereomers, each peptide having at least 6 amino acids and having a net positive charge which is greater than +1, said peptide comprising a hydrophobic L-amino acid, a positively charged L-amino acid and a D-amino acid, said mixture being obtained by solid phase synthesis wherein at each coupling step a mixture composed of 1 eq of each of the amino acids is added to the reaction, followed by HF cleavage.