title: LH-RH antagonists: further analogs with ring-substituted aromatic residues.
abstract: Although the systematic substitution of benzene and other aromatic ring systems with various atoms and groups has been a standard approach in conventional pharmaceutical research, it has only recently received the attention it deserves in peptide research. The observation that D-p-Cl-Phe inserted in position 2 of certain LH-RH (luteinizing hormone-releasing hormone) analogs results in large improvements in antagonist activity led us to examine the effect of this and other substituents on position 1 and 2 D-phenylalanyl analog side chains. Analogs containing two D-p-Cl-phenylalanines were found to be particularly powerful competitive inhibitors when assayed in cycling rat for blockade of ovulation. Analogs with non-aromatic amino acids in the first position exhibited much lower activities.
mesh_terms: D000818:Animals; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors*; D010060:Ovulation / Q000187:drug effects; D010649:Phenylalanine / Q000502:physiology; D051381:Rats
chemical_list: D007987:Gonadotropin-Releasing Hormone; D010649:Phenylalanine