Lollipop containing Glycyrrhiza uralensis extract reduces Streptococcus mutans colonization and maintains oral microbial diversity in Chinese preschool children

The anticariogenic activity of the extract of Glycyrrhiza uralensis (licorice) has been well documented. We recently developed an herbal lollipop containing licorice extracts with Glycyrrhizol A, the compound displaying strong antimicrobial activity against Streptococcus mutans. Preliminary testing showed that the herbal lollipop reduced salivary S. mutans counts in vivo. In this study, we aimed to further test the efficacy of this herbal lollipop for reducing salivary S. mutans levels, and investigate its impact on salivary microbiome. Using a well-established in vitro oral microbiome model, we showed that licorice extract displays targeted killing against S. mutans without affecting the biodiversity of the community. In vivo study corroborated in vitro findings, showing for high caries-risk children aged 3–6 with salivary S. mutans levels >5x10(5) cells/ml, daily use of 2 licorice-containing lollipops for 3 weeks significantly reduced salivary S. mutans levels compared to the control group. Salivary microbiome analysis showed either no change or even increase in phylogenetic diversity of the oral community following herbal lollipop usage. Although further study with longer term observation is needed, these results suggest that use of licorice extract-containing lollipops can be as a simple and effective way to reduce the risk of dental caries in children.