Evaluation of total phenol and flavonoid content and antimicrobial and antibiofilm activities of Trollius chinensis Bunge extracts on Streptococcus mutans

Dental caries is a chronic disease with multiple bacterial infections, Streptococcus mutans is the main cariogenic bacteria. Trollius chinensis Bunge is a common folk medicine in the Xinjiang area of China. In this study, we investigated the total flavonoid content and total phenol content in four types of T. chinensis Bunge extracts and the inhibitory effects of these extracts on S. mutans. Agar diffusion method was used to measure the inhibition zone diameters, and the minimum inhibitory concentration and minimum bactericidal concentration were determined by the twofold dilution method. Water extracts from T. chinensis Bunge and ethanol (30, 60, and 90%) extracts at different concentrations could significantly inhibit the growth of S. mutans. Among them, 30% ethanol extract exhibited the best antibacterial and antibiofilms effect. Biofilm research (crystal violet staining and CLSM) showed that 30% ethanol extract of T. chinensis Bunge plays an important role in inhibiting S. mutans growth and the number of biofilms. The results indicate that T. chinensis Bunge extract has good antibacterial and anti-biofilm activity on S. mutans. It has the potential to be developed for the treatment of caries in clinical application.

Keywords: Streptococcus mutans; Trollius chinensis Bunge; antibiofilms; confocal laser scanning microscopy.