In 2007, Kimata and co-workers [118] reported the synthesis and assessment of multiple PrP-res accumulation inhibitors according to the structure of edaravone, in which the most potent compound 163 (Fig. 16 ) displayed PrP-res inhibitory effect in the ScN2a cells with IC 50 value of 3 nM, which was 130 times more active than quinacrine and more than 300-fold effective than edaravone.