Abstract: New peptidic derivatives having the general formula (I): X.sub.1 X.sub.2 X.sub.3 Ile X.sub.5 X.sub.6 wherein X.sub.1 is hydrogen, a rest of histidin, of acetyl-histidin or of D-histidin, X.sub.2 is a rest of alanin, of leucin, of tryptophan, of phenylalanin as well as their homologs in D series, X.sub.3 is a rest of alanin as well as its D series homolog, X.sub.5 is a rest of isoleucin, of alanin, of valin, of norleucin, of leucin and of aspanic acid as well as their D series homologs, X.sub.6 is a rest of tryptophan, of leucin, of isoleucin, of norleucin and their D series homologs, method for the preparation and application of such new derivatives as medicaments.

Abstract: A peptide derivative having the formula: ##STR1## wherein X.sub.1 is hydrogen or cysteine residue,X.sub.3 is a cysteine or alanine residue,X.sub.4 is a residue of asparagine, phenylalanine, leucine, isoleucine, alanine, valine, glycine and their homologues in the D series,X.sub.6 is a residue of tryptophan, phenylalanine, leucine, isoleucine, alanine, valine, glycine, serine, lysine, aspartic acid, tyrosine, threonine and their homologues in the D series,X.sub.9 and X.sub.17 are a residue of glutamic acid, aspartic acid, lysine, arginine, tyrosine, leucine and their homologues in the D series,X.sub.11 is a cysteine or alanine residue,X.sub.14 is a residue of tyrosine, phenylalanine, leucine, isoleucine, alanine, valine, glycine, serine, lysine, aspartic acid, threonine and their homologues in the D series,X.sub.21 is hydrogen or a tryptophan or D-tryptophan residue, and the derivatives possessing, where appropriate, one or two disulfide bridges, with the proviso that X.sub.