NEW CYCLIC CATIONIC PEPTIDES WITH ANTIMICROBIAL ACTIVITY

A series of cationic cyclic peptides, useful for the treatment of infectious diseases in both human and veterinary clinical/surgical environment are described herein. The peptides of the invention have a length of 15 to 21 amino acids, and show a sequence A-B-C- D-C'-B'-A', wherein units A and A' correspond to -NH2 terminal and - COOH terminal regions; units B and B' correspond to cyclizable amino acids containing sulfur; units C and C are sequences of 5 amino acids selected among hydrophobic amino acids, basic amino acids and amino acids forming hydrogen bonds; unit D is a dipeptide consisting of glycine and one basic amino acid. Said peptides show significant antibacterial activity, associated with high stability and resistance to the action of bacterial endopeptidases, and weak or null toxicity against eukaryotic cells. In particular, the diposition of hydrophobic amino acids in discrete regions, separate from charged amino acids, gives the peptides high activity, also associated with significant salt-insensitivity. The invention also relates to the synthesis of said peptides, relative pharmaceuticals compositions, and use of said peptides in the treatment of infections caused by bacteria, fungi and/or yeasts.