Two novel small molecule gonadotropin-releasing hormone (GnRH) receptor antagonists (12 and 13) of the furamide-class were synthesized and evaluated in vitro for their receptor binding affinities for the rat GnRH receptor. Radiolabeling with no carrier added fluorine-18 of the appropriate precursors was investigated in a one-step reaction. LogP (Octanol/PBS pH 7.4) and serum stability of the compounds were investigated. The antagonists showed low nM affinity for the rat GnRH receptor. (18)F-radiolabled compounds were obtained in high radiochemical purity (>95%) and specific activity (>75 GBq/μmol). These findings suggest this class of compounds holds promise as potential probes for PET targeting of GnRH-receptor expression.
Keywords: Fluorine-18; Gonadotropin-releasing hormone (GnRH) receptor antagonists; Luteinizing hormone releasing hormone (LHRH); Positron emission tomography (PET); Small molecule.
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