Oroxylin a glucuronide as a novel class of reversible inhibitors of Sortase a, combats MRSA-induced infections

The main purpose of this study was to study the therapeutical effect of oroxylin A glucuronide (OAG) on methicillin-resistant Staphylococcus aureus (MRSA). By substrate peptide reaction-based fluorescence resonance energy transfer (FRET) screening, we identified that OAG was an efficient inhibitor of Sortase A (SrtA) with an IC50 of 45.61 μg mL-1, and achieved efficacy in the treatment of Staphylococcus aureus (S. aureus) infections. We further demonstrated that OAG inhibited the adhesion of the S. aureus to fibrinogen, the surface protein A anchoring and diminished biofilm formation. Results obtained from fluorescence quenching assay elucidated a direct interaction between OAG and SrtA. Employing molecular dynamics simulations, we proved that OAG binds to the binding sites of R197, G192, E105, and V168 in the SrtA. Notably, OAG exhibited a robust therapeutic effect in a MRSA-induced pneumonia model. We identified that OAG as a novel class of reversible inhibitors of SrtA, combats MRSA-induced Infections.