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 Cudrania tricuspidata (C. tricuspidata) extract on cariogenic bacteria Streptococcus mutans (S. mutans). 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 C. tricuspidata 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. S. mutans virulence gene expression analysis showed that it inhibited the expression of gbpB and spaP, which mediate bacterial attachment to the tooth surface, and that of genes contributing to biofilm formation (gtfB, gtfC, and gtfD) and acid resistance (brpA and relA), and regulation (vicR). Analysis using UPLC-Q-TOF-MS/MS showed that the main component was phenylpropanoids. These results suggest that C. tricuspidata may inhibit the cariogenic properties associated with the expression of caries-related genes in S. mutans.