Antibacterial effects of Ursolic acid against cariogenic bacteria

Objectives: Dental caries are caused by endogenous infection with bacteria resident in the oral cavity. Cariogenic bacteria existed in dental plaque cause infectious disease. Recently, many investigators have reported that experimental studies of caries prevention using a various antibacterial products. We focused on Ursolic acid that present in the leaf of loquat and the calyx of persimmon. It was used for cleaning the tooth as a toothpick since ancient times in Japan. In this study, we investigated the antibacterial effects of Ursolic acid on Streptococci and Actinomyces by in vitro and in vivo experiments. Methods: SM-resistant Streptococcus mutans PS-14 (S.mutans) and Actinomyces viscosus ATCC19246 (A.viscosus) was used in this experiment. Ursolic acid (Sigma) was used as antibacterial material. We investigated the antibacterial activity against S. mutans and A. viscosus by minimum inhibitory concentration (MIC) and determination of inhibition of Glucosyltransferase (GTF) activity. For in vivo caries experiments, JCL-Sprague-Dawley rats were orally infected with S. mutans and A. viscosus. After sacrifice, the caries scores of the mandibles were determined by keys methods. Results: The MIC of Ursolic acid against S.mutans was 7.5–15 mg/ml, A.viscosus was 15–30 mg/ml. Ulsoric acid was significantly inhibited Waterinsoluble Glucan (WIG) synthesis by GTF activity test. In addition Ursolic acid have an inhibitory effect on the adhesion of S.mutans and A.viscosus by in vivo caries experiments. And dental caries scores were significantly decreased in the group given the Ursolic acid. Conclusion: These results suggest that Ursolic acid have antibacterial activity against S.mutans and A.viscosus. Furthermore we consider that Ursolic acid can be used in preventional food additives against dental caries.