Effects of ginkgoneolic acid on the growth, acidogenicity, adherence, and biofilm of Streptococcus mutans in vitro

Ginkgo biloba has long been used in traditional Chinese medicine. In this study, ginkgoneolic acid, a kind of compound extracted from G. biloba, was investigated for its effects on growth, acid production, adherence, biofilm formation, and biofilm morphology of Streptococcus mutans. The results showed that ginkgoneolic acid inhibited not only the growth of S. mutans planktonic cells at minimum inhibitory concentration (MIC) of 4 μg/mL and minimum bactericidal concentration (MBC) of 8 μg/mL but also the acid production and adherence to saliva-coated hydroxyapatite of S. mutans at sub-MIC concentration. In addition, this agent was effective in inhibiting the biofilm formation of S. mutans (MBIC(50) = 4 μg/mL), and it reduced 1-day-developed biofilm of S. mutans by 50 % or more at low concentration (MBRC(50) = 32 μg/mL). Furthermore, the present study demonstrated that ginkgoneolic acid disrupted biofilm integrity effectively. These findings suggest that ginkgoneolic acid is a natural anticariogenic agent in that it exhibits antimicrobial activity against S. mutans and suppresses the specific virulence factors associated with its cariogenicity.