New Series of Antiprion Compounds:  Pyrazolone Derivatives Have the Potent Activity of Inhibiting Protease-Resistant Prion Protein Accumulation

To find effective antiprion compounds, we synthesized and evaluated various pyrazolone derivatives. Seven of 19 compounds showed inhibition of PrP-res accumulation and the remarkably active compound 13 showed an IC₅₀ value of 3 nM in both ScN2a and F3 cell lines. Findings from studies on physicochemical and biochemical properties suggest that the action mechanism of these compounds does not correlate with any antioxidant activities, any of hydroxyl radical scavenging activities, or any SOD-like activities.