Abstract: The present invention provides a peptide represented by the amino acid sequence formula (A): H-X1-X2-X3-X4-Gly-X6-X7-Asp-Gln-R  (A) wherein: each of X1 and X3 independently represents Arg or Lys, each of X2, X4 and X6 independently represents Ile or Leu, and X7 represents Phe, Tyr or Trp; and R represents -NH2, -Leu-NH2, -Leu-Ser-NH2, -Leu-Ser-Lys-NH2, -Leu-Ser-Arg-NH2, -Leu-Ser-Lys-Leu-NH2, or -Leu-Ser-Arg-Leu-NH2; and a salt thereof. (In the above, Gly stands for a glycine residue, Asp stands for an aspartic acid residue, Gln stands for a glutamine residue, Arg stands for an arginine residue, Lys stands for a lysine residue, Ile stands for an isoleucine residue, Leu stands for a leucine residue, Phe stands for a phenylalanine residue, Tyr stands for a tyrosine residue, Trp stands for a tryptophan residue, and Ser stands for a serine residue.) The peptide acts on glutamate receptors and is expected to be useful in the treatment of cerebral nerve diseases associated with glutamic acid.

Abstract: The present invention relates to crosslink-stabilized analogs of indolicidin, which is a naturally occurring peptide having the amino acid sequence Ile-Leu-Pro-Trp-Lys-Trp-Pro-Trp-Trp-Pro-Trp-Arg-Arg-CONH2 (“Indol 1-13;” SEQ ID NO: 1). The crosslinked indolicidin (“X-indolicidin”) analogs of the invention include, for example, analogs such as Indol 1-13(W6,9), which has the structure Ile-Leu-Pro-Trp-Lys-Trp-Pro-Trp-Trp-Pro-Trp-Arg-Arg-CONH2 (SEQ ID NO: 3), and Indol 1-13/6,9C(C6,9), which has the structure Ile-Leu-Pro-Trp-Lys-Cys-Pro-Trp-Cys-Pro-Trp-Arg-Arg-CONH2 (SEQ ID NO: 4), where a crosslink formed between the first and last underlined amino acid residues. In addition, the invention provides nucleic acid molecules encoding the X-indolicidin analogs of the invention, particularly precursors of such analogs.