Inhibition of formation of protease-resistant prion protein by Trypan Blue, Sirius Red and other Congo Red analogs

Five compounds related to Congo Red were found to inhibit generation of pro tease-resistant prion protein in a cell-free system. In this assay Trypan B lue, Evans Blue, Sirius Red F3B, Primuline and Thioflavin-S were all more i nhibitory than Congo Red itself. In scrapie-infected mouse neuroblastoma ce lls one compound, Sirius Red F3B, was capable of blocking the formation of protease-resistant prion protein to a similar extent as Congo Red; however, the other four compounds were less effective. Some of these compounds shou ld be considered for testing in TSE disease models in live animals.