In silico/in vitro screening and hit evaluation identified new phenothiazine anti-prion derivatives

Prion diseases or transmissible spongiform encephalopathies (TSEs) are a group of rare neurodegenerative disorders. TSEs are characterized by the accumulation of prions (PrP^Sc) that represent pathological isoforms of the physiological cellular prion protein PrP^C. Although the conversion of PrP^C to PrP^Sc is still not completely understood, blocking this process may lead to develop new therapies. Here, we have generated a pharmacophore model, based on anti-prion molecules reported in literature to be effective in phenotypic assay. The model was used to conduct a virtual screen of commercial compound databases that selected a small library of ten compounds. These molecules were then screened in mouse neuroblastoma cell line chronically infected with prions (ScN2a) after excluding neurotoxicity. 1 has been identified as the therapeutic hit on the basis of the following evidence: chronic treatments of ScN2a cells using 1 eliminate PrP^Sc loaded in both Western blotting analysis and Real-Time Quaking-Induced Conversion (RT-QuIC) assay. We also proposed the mechanism of action of 1 by which it has the ability to bind PrP^C and consequentially blocks prion conversion. Herein we describe the results of these efforts.