Rosmarinic acid exhibits broad anti-enterovirus A71 activity by inhibiting the interaction between the five-fold axis of capsid VP1 and cognate sulfated receptors.

Enterovirus A71 (EV-A71), a positive-stranded RNA virus of the Picornaviridae family, may cause neurological complications or fatality in children. We examined specific factors responsible for this virulence using a chemical genetics approach. Known compounds from an anti-EV-A71 herbal medicine, Salvia miltiorrhiza (Danshen), were screened for anti-EV-A71. We identified a natural product, rosmarinic acid (RA), as a potential inhibitor of EV-A71 by cell-based antiviral assay and in vivo mouse model. Results also show that RA may affect the early stage of viral infection and may target viral particles directly, thereby interfering with virus-P-selectin glycoprotein ligand-1 (PSGL1) and virus-heparan sulfate interactions without abolishing the interaction between the virus and scavenger receptor B2 (SCARB2). Sequencing of the plaque-purified RA-resistant viruses revealed a N104K mutation in the five-fold axis of the structural protein VP1, which contains positively charged amino acids reportedly associated with virus-PSGL1 and virus-heparan sulfate interactions via electrostatic attraction. The plasmid-derived recombinant virus harbouring this mutation was confirmed to be refractory to RA inhibition. Receptor pull-down showed that this non-positively charged VP1-N104 is critical for virus binding to heparan sulfate. As the VP1-N104 residue is conserved among different EV-A71 strains, RA may be useful for inhibiting EV-A71 infection, even for emergent virus variants. Our study provides insight into the molecular mechanism of virus-host interactions and identifies a promising new class of inhibitors based on its antiviral activity and broad spectrum effects against a range of EV-A71.

The anti-tumor efficiency of pterostilbene is promoted with a combined treatment of Fas signaling or autophagy inhibitors in triple negative breast cancer cells.

High expression of vimentin, a canonical mesenchymal marker, is linked with poor prognosis in triple negative breast cancer (TNBC), implying that vimentin may be a potential biomarker in the application of TNBC therapy. Pterostilbene (PTE) has shown anti-invasion activity, and thus, we investigated whether PTE inhibited the epithelial-mesenchymal transition (EMT) in TNBC. Here, we show that PTE decreases the vimentin expression, but that the effect was transient. PTE stimulated Fas signaling, which drives EMT by the ERK1/2 and GSK3ß/ß-catenin pathways, supporting Fas signaling induction involved in EMT regulation. PTE also triggered autophagy in TNBC. The treatment of TNBC with 3-methyladenine an autophagy inhibitor, not only sustained PTE-inhibited EMT but also significantly promoted anti-proliferation, which indicates that autophagy plays a cyto-protective role and is associated with EMT. Taken together, these data showed that Fas signaling and autophagy accelerated the aggressiveness of TNBC. Inhibition of autophagy or Fas signaling may provide novel targets for TNBC therapy.