Inhibitory Effects of Flavonoids from Spatholobus suberectus on Sortase A and Sortase A-Mediated Aggregation of Streptococcus mutans

Abstract

Seven flavonoids were isolated from <i>Spatholobus suberectus</i> via repetitive column chromatography and high-performance liquid chromatography. The chemical structures of these compounds were identified by spectroscopic analysis and comparison with values reported in the literature. Among the flavonoids tested, 7-hydroxy-6-methoxyflavanone (<b>1</b>) and formononetin (<b>4</b>) exhibited strong inhibitory activity against <i>Streptococcus mutans</i> SrtA, with IC₅₀ values of 46.1 and 41.8 µM, respectively, but did not affect cell viability. The onset and magnitude of inhibition of saliva-induced aggregation in <i>S. mutans</i> treated with compounds <b>1</b> and <b>4</b> were comparable to the behavior of a <i>srtA</i>-deletion mutant without treatment.