Novel chemotherapeutic-approach using natural molecules on biofilm and caries development

The development of novel chemotherapeutic agents that disrupt the formation and virulence of dental biofilms is a promising route to prevent or reduce oral infectious diseases such as dental caries. Aims: The aim of the present study was to examine whether the association of bioactive natural molecules (myricetin and tt-farnesol) enhance the cariostatic properties of fluoride by acting cooperatively on the expression of virulence of Streptococcus mutans. Methods: The effects of topical application of combinations of 1 mM myricetin, 2.5 mM tt-farnesol and fluoride (125 or 250 ppm F) on S. mutans UA159 biofilm formation in vitro and development of caries in vivo were examined. The biofilms were subjected to biochemical, structural (laser scanning confocal fluorescence microscopy) and molecular (real-time PCR) analyses. Sprague-Dawley rats were infected with S. mutans UA159 and treated twice daily with the combinations of agents using our rat dental caries model. Results: The biofilms treated with combinations of agents displayed less biomass and acidogenicity, and fewer insoluble extracellular polysaccharides (EPS) than did those treated with fluoride alone or vehicle control (P<0.05). The spatial distribution and biovolume measurements of EPS-matrix and bacteria were also markedly affected by the combination of agents; the biovolume of EPS was significantly reduced when compared to fluoride alone or vehicle control (P<0.05). Furthermore, the agent combinations disrupted the pattern of gtfBCD, aguD and atpD expression by S. mutans biofilms. The development of dental caries was significantly reduced by the combination therapies in vivo (P<0.05). The combination of natural molecules with 125 ppm F was particularly effective, and the cariostatic properties were comparable with those observed with 250 ppm F (positive control). Conclusion: Results from these studies showed that combination of myricetin, tt-farnesol and fluoride is an alternative and effective anti-caries chemotherapeutic approach. (NIH/NIDCR DE016139, DE18023 and Chonbuk National University Overseas-Research Funds)