Stilbene Compounds Inhibit the Replications of Various Strains of Prions in the Levels of Cell Culture, PMCA, and RT-QuIC Possibly via Molecular Binding.

Resveratrol shows the ability to block prion replication in a scrapie-infected cell line, SMB-S15, and remove the infectivity of the treated cell lysates in an experimental bioassay. In this study, we compared the effectiveness of three stilbene compounds, resveratrol (Res), pterostilbene (Pte), and piceatannol (Pic), on inhibiting prion propagations in the levels of cell culture, PMCA, and RT-QuIC. All three chemicals showed active suppressions on PrPSc replication in SMB-S15 cells, in which Res seemed to be the most active one, followed by Pic and Pte. Mouse PrP-based PMCA tests using the lysates of SMB-S15 cells and brain homogenates of scrapie agents S15-, 139A-, or ME7-infected mice verified that Res, Pte, and Pic inhibited the amplifications of PK-resistant signals. Res was also the most effective one. Mouse PrP-based RT-QuIC using the above seeds demonstrated that three stilbenes efficiently inhibited the fibril formation. However, Pic was the most effective one, followed by Res and Pte. Furthermore, the inhibition activities of the three stilbenes on the brain-derived prion from a 263K-infected hamster were tested with hamster PrP-based PMCA and RT-QuIC. The results indicated that Pic was the most effective one apparently, followed by Res and Pte. According to the results of Biacore, Res showed binding affinities much stronger than those of Pte, whereas both revealed markedly stronger binding affinities with mouse PrP. Our data here indicate that different stilbenes have the ability to block PrPSc replication in vitro with different prion species. The suppressive effects of stilbene compounds are likely associated with their molecular binding activities with PrPs.