Abstract: This invention provides methods of treatment using retro-inverso peptides derived from interleukin-6 (IL-6) having between 15 and about 40 amino acids, and including the sequence that is retro-inverso with respect to SEQ ID NO: 1, i.e. wherein said peptide comprises the sequence D-Glu-D-Ala-D-Met-D-Lys-D-Pro-D-Leu-D-Asn-D-Leu-D-Asn-D-Asn-D-Glu-D-Ala-D-Leu-D-Ala-D-Glu. The peptides of the invention have the same activity as native IL-6 and also have neurotrophic activity. The peptides of the invention are also less susceptible to proteolytic degradation in vivo because of their D-amino acid linkage.

Abstract: Peptide derivatives which are antagonists of neurokinin A. The derivatives have a modified peptide bond having a reduced amide and a fluorinated alkyl attached to the nitrogen atom of the modified peptide bond. For example, Asp-Ser-Phe-Val-Gly-Leu&PSgr;[CH2N(CH2CF3)]Leu(NH2).

Abstract: A method of synthesis of a partially retro-inverso peptide incorporating at least one malonyl residue of formula (III) ##STR1## wherein R represents the side chain of an .alpha.-amino acid, is described which is characterized in that said malonyl residue is incorporated by condensing a 5-substituted-2,2-dimethyl-1,3-dioxane-4,6-dione of formula (IV) ##STR2## wherein R' is the side-chain R wherein the functional groups, if any, are suitably protected, with an amino acid, amino acid amide, peptide fragment, or pseudo-peptide fragment wherein the terminal carboxyl group, if present, and the possible side-chain functionalities are suitably protected and the reactive amino group is tri-alkyl-silylated.The new compounds of formula (VI) and a process for the preparation of a partially retro-inverso tuftsin analog which involves use of said method and said intermediate are also described and claimed.