Abstract: Novel peptide compounds of the formulaX.sup.1 --X.sup.2 --X.sup.3 --X.sup.4 --X.sup.5 --X.sup.6 --X.sup.7 --X.sup.8 --Pro--Ware provided together with their acid addition salts and their complexes with pharmaceutically acceptable metals. The compounds are LH-RH analogues and together with their salts and complexes exhibit LH-RH antagonist activity.In the formulaX.sup.1 is selected from pyroglutamyl, a group V.sup.1 -Pro- where V.sup.1 is acyl, alkyloxycarbonyl or aralkyloxycarbonyl, and a group V.sup.2 --CO-- where V.sup.2 is cycloalkyl;X.sup.2 is selected from histidyl and a direct bond;X.sup.3 is selected from phenylalanyl optionally substituted in the benzene ring and tryptophyl;X.sup.4 is selected from glycyl, seryl, alanyl (D- or L), D-leucyl and D-valyl;X.sup.5 is phenylalanyl optionally substituted in the benzene ring;X.sup.6 is selected from glycyl, alanyl (D- or L-), D-leucyl and D-valyl;X.sup.7 is selected from phenylalanyl optionally substituted in the benzene ring and leucyl;X.sup.

Abstract: Novel peptide compounds of the formulaGlu-His-X.sup.3 -X.sup.4 -X.sup.5 -X.sup.6 -X.sup.7 -X.sup.8 -Pro-Ware provided together with their acid addition salts and their complexes with pharmaceutically acceptable metals. The compounds are LH-RH analogues and together with their salts and complexes exhibit LH-RH agonist activity. In the formulaX.sup.3 and X.sup.5 are the same or different and each is phenylalanyl optionally substituted in the benzene ring;X.sup.4 and X.sup.6 are the same or different and each is selected from glycyl, alanyl (D- or L-) and asparaginyl;X.sup.7 is a radical of a neutral hydrophobic nonsulphur containing non-heterocyclic amino acid;X.sup.8 is a radical of a basic amino acid or is glycyl or phenylalanyl optionally substituted in the benzene ring; andW is selected from glycine amide and a group --NR.sup.1 R.sup.2.All references are to the L-amino acids and their radicals except in the case of glycine and unless otherwise stated.

Abstract: Compounds of formula (VIII) whereinR.sup.1, r.sup.2, r.sup.3, r.sup.4 and R.sup.5 are each selected from hydrogen and an hydroxyl group and at least four are hydrogen;B is an alkylene chain of from 1 to 4 carbon atoms;R is selected from hydrogen and an alkyl group of from 1 to 4 carbon atoms;A is selected from a bond and a straight or branched, optionally substituted alkylene chain of 1 to 6 carbon atoms, andX.sup.1 and X.sup.2 are each selected from hydrogen and an iodine radioisotope.Compounds of this formula are of value as agents for use in the radioimmunoassay of corresponding genins of formula (V) and derivatives thereof. Also provided by the invention are a radioimmunoassay method utilizing compounds of formula (VIII) and a test kit suitable for use in performing the assay.