Isovitexin, a Potential Candidate Inhibitor of Sortase A of Staphylococcus aureus USA300.

Staphylococcus aureus (S. aureus) causes a broad variety of diseases. The spread of multidrugresistant S. aureus highlights the need to develop new ways to combat S. aureus infections. Sortase A (SrtA) can anchor proteins containing LPXTG binding motifs to the bacteria surface and plays a key role in S. aureus infections, making it a promising antivirulence target. In the present study, we used aSrtA activity inhibition assay to discover that isovitexin, a Chinese herbal product, can inhibit SrtA activity with an IC50 of 28.98 μg/ml. Using a fibrinogenbinding assay and a biofilm formation assay, we indirectly proved the SrtA inhibitory activity of isovitexin. Additionally, isovitexin treatment decreased the amount of staphylococcal protein A (SpA) on the surface of the cells. These data suggest that isovitexin has the potential to be an anti-infective drug against S. aureus via the inhibition of sortase activity.