The Antimicrobial Effects of Licorice Extract against Streptococcus mutans as a Potential Oral Gel against Dental Caries.

INTRODUCTION

Dental caries is a prevalent chronic infectious disease primarily associated with Streptococcus mutans. Natural compounds with antimicrobial properties, such as licorice (Glycyrrhiza glabra), offer promising alternatives for oral health care.

METHODS

Licorice roots were authenticated by a botanist and processed into an extract. The extract was formulated into an oral gel (100 μg/mL) and sterilized using gamma irradiation. The minimum inhibitory concentration (MIC) of the gel against S. mutans was determined by the agar dilution method. Sub-MIC concentrations were used in a time-kill assay to assess antibacterial efficacy. A reduction of ≥3 log10 CFU/mL was considered indicative of antibacterial activity. Data were analyzed using the Shapiro-Wilk test, Kruskal-Wallis, and Tukey's post hoc test (SPSS v25, p < 0.05).

RESULTS

The MIC of the gel was found to be 1260 μg/mL. Time-kill assays using concentrations of 1.4 and 1.8 μg/mL showed a significant reduction in bacterial count over time, demonstrating effective antibacterial action against S. mutans.

DISCUSSION: The results suggest that even sub-MIC levels of licorice gel can significantly inhibit S. mutans, highlighting its potential for incorporation into preventive or therapeutic oral health products.

CONCLUSION

Licorice extract gel exhibits promising antimicrobial activity against S. mutans and may be considered a potential natural agent in oral formulations targeting dental caries.