Effect of Cudrania tricuspidata on Cariogenic Properties and Caries-Related Gene Expression in Streptococcus mutans

The purpose of this study was to evaluate the gene expression pattern of the caries-inhibiting effect of <i>Cudrania tricuspidata</i> (<i>C. tricuspidata</i>) extract on cariogenic bacteria <i>Streptococcus mutans</i> (<i>S. mutans</i>). We examined bacterial growth, tooth surface attachment, biofilm formation, acid production, free calcium release, and toxicity gene expression. The major components of the extract were investigated by UPLC-Q-TOF-MS analysis. Exposure to <i>C. tricuspidata</i> inhibited bacterial growth and attachment at concentrations of ≥15 μg/mL. Inhibition effects on biofilm formation, acid production, and free calcium release due to acid production were observed at concentrations ≥ 30 μg/mL. <i>S. mutans</i> virulence gene expression analysis showed that it inhibited the expression of <i>gbpB</i> and <i>spaP</i>, which mediate bacterial attachment to the tooth surface, and that of genes contributing to biofilm formation (<i>gtfB</i>, <i>gtfC</i>, and <i>gtfD</i>) and acid resistance (<i>brpA</i> and <i>relA</i>), and regulation (<i>vicR</i>). Analysis using UPLC-Q-TOF-MS/MS showed that the main component was phenylpropanoids. These results suggest that <i>C. tricuspidata</i> may inhibit the cariogenic properties associated with the expression of caries-related genes in <i>S. mutans</i>.