Inhibitory Effects of Ethanol Extracts of <i>Ginkgo biloba</i> Leaves on Physiological Activities of <i>Streptococcus mutans</i> in Different Carbohydrate Conditions

Background: Dental caries is closely associated with physiological activities of Streptococcus mutans, including growth, acid production, calcium ion (Ca2+) release, and biofilm formation. Although the antimicrobial properties of ethanol extracts of Ginkgo biloba leaves (GLE) against various cariogenic and periodontal pathogens have been reported, their effects on physiological responses of S. mutans under different carbohydrate environments remain unclear. This study aimed to investigate the influence of GLE on the physiological activities of S. mutans in brain heart infusion broth, and in media supplemented with 1% sucrose or 1% xylitol. Based on these findings, we aimed to evaluate the potential of GLE as a natural functional material for inhibiting S. mutans–associated virulence and preventing dental caries. Methods: To evaluate the antimicrobial activity of GLE against S. mutans under various media conditions, a disk diffusion test was performed. Effects of GLE on physiological activities of S. mutans were assessed by measuring bacterial growth and conducting assay for biofilm formation, Ca2+ release, acidogenicity, and buffering capacity. Results: GLE exhibited significant, dose-dependent antimicrobial activity against S. mutans, particularly in sucrose-containing media. Increasing GLE concentrations significantly inhibited bacterial growth, biofilm formation, and Ca2+ release. Notably, GLE at concentrations of ≥5 mg/ml effectively suppressed multiple physiological activities of S. mutans. In addition, GLE reduced bacterial acid production regardless of concentration and enhanced the buffering capacity of the culture media. Conclusion: GLE has the potential to serve as a safe and effective natural functional material with physiological activity inhibition and anticariogenic potential GLE inhibits physiological activities of S. mutans, including biofilm formation and Ca2+ release, particularly in sucrose-containing media, and effectively neutralizes S. mutans-induced the acidic conditions by, thereby contributing to its anticariogenic effects.