title: New degradation product of des-Gly10-NH2-LH-RH-ethylamide (fertirelin) in aqueous solution.
abstract: A new degradation product was found in an ampule preparation of des-Gly10-NH2-LH-RH-ethylamide (fertirelin) stored at room temperatures. The same product, produced at a higher temperature, was identified to be a diastereomeric mixture of cyclo(His-Trp) by proton nuclear magnetic resonance spectroscopy, mass spectrometry, and comparison with authentic samples. Preferred conformations regarding substituents on the diketopiperazine ring of cyclo(His-Trp) were calculated using coupling constants between vicinal protons.
authors.affiliation: Animal Health Research Laboratories, Takeda Chemical Industries, Ltd., Osaka, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Okada
authors.forename: T
authors.initials: T
authors.lastname: Seo
authors.forename: F
authors.initials: F
authors.lastname: Kasahara
authors.forename: K
authors.initials: K
authors.lastname: Takeda
authors.forename: S
authors.initials: S
authors.lastname: Kondo
mesh_terms: D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D004355:Drug Stability; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D013058:Mass Spectrometry; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D012996:Solutions
chemical_list: D012996:Solutions; D007987:Gonadotropin-Releasing Hormone; C009936:fertirelin