Astilbin Inhibits the Activity of Sortase A from .

() is the primary etiological agent of dental caries. The enzyme sortase A (SrtA) is responsible for anchoring bacterial cell wall surface proteins involved in host cell attachment and biofilm formation. Thus, SrtA is an attractive target for inhibiting dental caries caused by -associated acid fermentation. In this study, we observed that astilbin, a flavanone compound extracted from , has potent inhibitory activity against the SrtA, with an IC of 7.5 μg/mL. In addition, astilbin was proven to reduce the formation of biofilm while without affecting the growth of . The results of a molecular dynamics simulation and a mutation analysis revealed that the Arg213, Leu111, and Leu116 of SrtA are important for the interaction between SrtA and astilbin. The results of this study demonstrate the potential of using astilbin as a nonbactericidal agent to modulate pathogenicity of by inhibiting the activity of SrtA.