Abstract: Novel growth hormone releasing factor analogs are presented having a sequence of from about twenty-nine (29) to about forty-four (44) amino acids (SEQ ID NO: 6) wherein Xaa at position 1 is His, 3-MeHis, desNH.sub.2 His, Tyr, or desNH.sub.2 Tyr; Xaa at position 2 is Val, Leu, lie, Ala, D-Ala, N-Methyl-D-Ala, Gly, NIe, or Nval; Xaa at position 8 is Gln, Ser, or Thr; Xaa at position 15 is Ala or Leu; Xaa at position 27 is Met, Nle or Leu; Xaa at position 28 is Ser or Asn; Xaa at position 29 is an amino acid residue sequence (SEQ ID NO: 7) or fragments thereof where the fragment is reduced in number by one to fifteen amino acid residues from the carboxyl-terminus, where the carboxyl terminus can be the free carboxylic acid or the corresponding amide, and the pharmaceutically acceptable acid or base addition salts thereof.

Abstract: Novel GRF PEPTIDES having Thr, Val or Ile at position 2, having an amino acid selected from the group consisting of Ala, Val, Leu, Ile or Gly at position 15, and optionally substituted with Val or Ile at position 19 are described. Compositions and the method of stimulating the release of growth hormone utilizing GRF PEPTIDES having Thr, Val or Ile at position 2 and having an amino acid selected from the group consisting of Ala, Val, Leu, Ile or Gly at position 15 are also described. The GRF PEPTIDES of the present invention have enhanced stability in plasma.

Abstract: Novel growth hormone releasing factor analogs are presented having the formula: ##STR1## wherein R.sub.1 is His, 3-MeHis, desNH.sub.2 His, Tyr, or desNH.sub.2 Tyr; R.sub.2 is Val, Leu, or Ile; R.sub.3 is Ala; R.sub.4 is Met, Leu, Ile, or Nle; R.sub.5 is Ser or Asn; R.sub.6 is an amino acid residue sequence selected from Arg-Gln-Gln-Gly-Glu-Ser-Asn-Gln-Glu-Arg-Gly-Ala-Arg-Ala-Arg-Leu or fragments thereof where the fragment is reduced in number by one to fifteen amino acid residues from the amino acid residue which carries the substituent X; and X is either OH or NH.sub.2, and the pharmaceutically acceptable acid or base addition salts thereof. The novel growth hormone releasing factor analogs demonstrate enhanced potency for the released growth hormone, have enhanced enzymatic stability, and can be administered to a subject having a deficiency of growth hormone or for improvement of growth performance in livestock.

Abstract: Peptides which include unnatural amino acides and which either inhibit or promote the secretion of gonadotropins by the pituitary gland and inhibit the release of steroids by the gonads. Administration of an effective amount of such peptides that are GnRH antagonists prevents ovulation of female mammalian eggs and/or the release of steroids by the gonads. The antagonists may be used to treat steroid-dependent tumors, such as prostatic and mammary tumors. The peptides are analogs of the decapeptide GnRH wherein there is at least one residue of an unnatural amino acid in the 3-position, the 5-position, the 6-position and/or the 8-position. Such unnatural amino acids are useful in the synthesis of peptides and have the formula U*: ##STR1## where n is an integer from 1 to 6; Y is N--CN, N--CONHR.sub.9, S, O or CH--NO.sub.2 ; R.sub.9 is H, Ac, lower alkyl, aromatic or heterocyclic; X is NH, O, S, M.sub.1 (CH.sub.q).sub.p M.sub.2 or M.sub.1 --(CH.sub.2).sub.p' --M.sub.2 (CH.sub.2).sub.p" --M.sub.3, where M.sub.