Hydrophobic, aza-glycine analogues of luteinizing hormone-releasing hormone.
The effect of combination of the hydrophilic aza-Gly substitution (NHNHCO) at position 10 with hydrophobic, unnatural D-amino acids in position 6 on the potency of luteinizing hormone-releasing hormone (LH-RH) analogues has been investigated. Previously the aza-Gly residue was shown to provide protection from enzymatic cleavage and lead to potency increases in a less hydrophobic series. The compounds were prepared by coupling of the corresponding nonapeptide acids with semicarbazide hydrochloride by the N,N'-dicyclohexylcarbodiimide/1-hydroxybenzotriazole procedure. The required nonapeptide acids were prepared by the solid phase method on chloromethyl-polystyrene resin using HF/anisole deprotection. The products were purified by preparative reversed-phase high-performance liquid chromatography. The analogues were tested in a rat estrous cyclicity suppression assay designed to show the paradoxical antifertility effects of these compounds. The potencies of [6-(3-benzimidazol-2-yl)-D-alanine), 10-aza-glycine] LH-RH and [6-(3-(5,6-dimethylbenzimidazol-2-yl)-D-alanine), 10-aza-glycine] LH-RH are 40 and 190 times that of LH-RH respectively. The most active compound in this series is [6-(3-(2-naphthyl)-D-alanine), 10-aza-glycine] LH-RH with a potency 230 times that of LH-RH. This compound is 2.3 times as potent as the standard ([D-Trp6, Pro9-NHEt] LH-RH) and appears to be the most potent LH-RH agonist reported.
D000818:Animals; D001681:Biological Assay; D002851:Chromatography, High Pressure Liquid; D004971:Estrus / Q000187:drug effects; D005260:Female; D005998:Glycine / Q000031:analogs & derivatives* / Q000494:pharmacology; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000494:pharmacology; D006834:Hydrazines; D007202:Indicators and Reagents; D011247:Pregnancy; D051381:Rats; D013329:Structure-Activity Relationship
D006834:Hydrazines; D007202:Indicators and Reagents; D007987:Gonadotropin-Releasing Hormone; C010877:carbazic acid; D005998:Glycine