Abstract: Peptides containing in its amino acid chain a D-2-alkylTryptophan residue wherein the alkyl group has between one and three carbon atoms and having pharmacological activity similar to that of analogous peptides containing natural unsubstituted D-Tryptophan residues in place of the D-2-alkylTryptophan. These new peptides are more resistant to oxidative degradation which usually takes place, for example, in the presence of reactive radicals or during high energy sterilization than unsubstituted Tryptophan containing peptides. Specific peptides include His-D-2-alkyl-Trp-Ala-Trp-D-Phe-Lys-NH.sub.2, Ala-His-D-2-alkyl-Trp-Ala-Trp-D-Phe-Lys-NH.sub.2, Pyro-Glu-His-Trp-Ser-Tyr-D-2-alkyl-Trp-Leu-Arg-Pro-Gly-NH.sub.2, pyro-Glu-His-Tyr-Ser-Tyr-D-2-alkyl-Trp-Leu-Arg-Pro-NHCH.sub.2 CH.sub.3, D-Pro-Gln-Gln-D-Trp-Phe-D-Trp-2-alkyl-Trp-Met-NH.sub.2, Arg-D-Trp-N-methyl-Phe-D-2-alkyl-Trp-Leu-Met-NH.sub.2, D-Phe-Cys-Phe-D-2-alkyl-Trp-Lys-Thr-Cys-NHCH(CH.sub.2 OH)CHOHCH.sub.3 and D-Phe-Cys-Tyr-D-2-alkyl-Trp-Lys-Val-Cys-Trp-NH.

Abstract: D-2-Alkyl Tryptophan compounds for incorporation into various peptides during manufacture thereof or for substitution for D-Tryptophan residues in such peptides to provide a D-2-alkyl Tryptophan residue therein which enhances the stability and biological activity of the peptide.

Abstract: Peptides containing in its amino acid chain a D-2-alkylTryptophan residue wherein the alkyl group has between one and three carbon atoms and having pharmacological activity similar to that of analogous peptides containing natural unsubstituted D-Tryptophan residues in place of the D-2-alkylTryptophan. These new peptides are more resistant to oxidative degradation which usually takes place, for example, in the presence of reactive radicals or during high energy sterilization than unsubstituted Tryptophan containing peptides. Specific peptides include His-D-2-alkyl-Trp-Ala-Trp-D-Phe-Lys-NH.sub.2, Ala-His-D-2-alkyl-Trp-Ala-Trp-D-Phe-Lys-NH.sub.2, Pyro-Glu-His-Trp-Ser-Tyr-D-2-alkyl-Trp-Leu-Arg-Pro-Gly-NH.sub.2, Pyro-Glu-His-Ser-Tyr-D-2-alkyl-Trp-Leu-Arg-Pro-NHCH.sub.2 CH.sub.3, D-Pro-Gln-Gln-D-Trp-Phe-D-Trp-2-alkyl-Trp-Met-NH.sub.2, Arg-D-Trp-N-methyl-Phe-D-2-alkyl-Trp-Leu-Met-NH.sub.2, D-Phe-Cys-Phe-D-2-alkyl-Trp-Lys-Thr-Cys-NHCH(CH.sub.2 OH)CHOHCH.sub.3 and D-Phe-Cys-Tyr-D-2-alkyl-Trp-Lys-Val-Cys-Trp-NH.sub.2.

Abstract: A luteinizing hormone releasing hormone antagonist peptide is provided which effectively decreases plasma levels of estrogens and androgens. The peptide exhibits increased levels of potency while at the same time minimizing histamine releasing properties, vascular permeability (or edematogenic effects), hypotension, poor water solubility an inadequate duration of action associated with luteinizing hormone releasing hormone antagonist peptides of the past.