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A potent, highly insoluble, GnRH antagonist with a 2-phenyl-4-piperazinylbenzimidazole template and a quinoxaline-2,3-dione pharmacophore was modified to maintain GnRH antagonist activity and improve in vitro pharmaceutical properties. Structural changes to the quinoxaline-2,3-dione portion of the molecule resulted in several structures with improved properties and culminated in the discovery of 6-([4-[2-(4-tert-butylphenyl)-1H-benzimidazol-4-yl]piperazin-1-yl] methyl)quinoxaline (WAY-207024). The compound was shown to have excellent pharmacokinetic parameters and lowered rat plasma LH levels after oral administration.

2-Trifluoromethyl-4-aminobenzimidazoles were previously identified by screening to be active antagonists of the gonadotropin releasing hormone receptor (GnRH-R). Structure activity relationships and diversity oriented synthesis are shown here in greater detail. 2-Substituted benzimidazoles were synthesized in parallel by the coupling of carboxylic acids with a latent intermediate diamine monomer to yield the desired benzimidazoles in fair yields. A catch and release strategy was employed as a product isolation technique, followed by RP-HPLC to obtain products of desired purity for biological evaluation. Two libraries were prepared and screened to determine the optimal substitution for inhibitory activity against GnRH-R. The initial library focused on substituted phenyl, pyridine, and thiophenes. The follow-up library focused on substitution patterns observed in the initial library members and generated compounds with IC(50) values lower than 100 nM at the GnRH-R.

Rat osteo-testicular protein tyrosine phosphatase (OST-PTP), expressed in osteoblasts and testis, is a receptor-like transmembrane protein with two tandemly repeated phosphatase domains in the cytoplasmic region. In this report, we show that the first domain (CD1) is enzymatically active and appears to be influenced by the catalytically inactive second domain (CD2). The activity of CD1 is specific to phosphorylated tyrosine. Full-length OST-PTP protein expressed in COS cells has a molecular mass of approximately 185 kDa, and immunoprecipitates of this protein using OST-PTP-specific antisera show strong tyrosine phosphatase activity. Expression of OST-PTP mRNA in primary rat calvarial osteoblasts is temporally regulated, and peak expression is found at approximately day 15, which correlated well with the appearance of OST-PTP protein and its associated tyrosine phosphatase activity. Treatment of osteoblasts in culture with antisense oligonucleotides directed against the 5' untranslated region of OST-PTP results in abrogation of differentiation, confirming the functional importance of OST-PTP expression in osteoblast development.