Library Design, Synthesis, and Screening:  Pyridine Dicarbonitriles as Potential Prion Disease Therapeutics

Transmissible spongiform encephalopathies (TSEs) or prion diseases are a family of invariably fatal neurodegenerative disorders, and there are no effective therapeutics currently available. In this paper, we report on the design, synthesis, and screening of a series of pyridine dicarbonitriles as potential novel prion disease therapeutics. A virtual reaction-based library of 1050 compounds was constructed. Docking and evaluation using GOLD scores assisted the initial selection of compounds for synthesis. The selection was augmented with further compounds to increase structural diversity. A total of 45 compounds were synthesized via a one-pot three-component coupling reaction. The mechanism of the three-component coupling reaction was investigated, and it was discovered that chemical oxidation is required for the last step, forming the pyridine ring (aromatization). A total of 19 compounds were identified as binders to one or more forms of prion protein by in vitro screening using surface plasmon resonance (SPR). A selection of compounds were investigated for activity in cells, resulting in the discovery of a new inhibitor of PrP^Sc formation.