Antimicrobial Effects against Oral Pathogens and Cytotoxicity of Glycyrrhiza uralensis Extract

Abstract

We aimed to evaluate the antimicrobial effects ofGlycyrrhiza uralensisextract onStreptococcus mutansandCandida albicansand its biocompatibility for dental applications. The antimicrobial activity of theG. uralensisextracts at concentrations of 50, 100, 150, and 200 mu g/mL was assessed using agar disk diffusion tests, counting the total number of colony-forming units (CFUs), spectrophotometric growth inhibitory assays, and microbial morphology observations using scanning electron microscopy (SEM; Merin, Carl Zeiss, Oberkochen, Germany). We measured the polyphenol and flavonoid contents ofG. uralensisextracts using ultraviolet-visible spectrometry and the cytotoxicity of these extracts using an MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. We identified thatG. uralensisextracts had significant antimicrobial effects againstS. mutansandC. albicans. The optical density of the experimental groups significantly decreased compared with that of the control group. SEM images revealed that theG. uralensisextract affected the morphology and density ofS. mutansandC. albicans. The extract concentration of flavonoids, but not polyphenols, increased with increasing concentrations of theG. uralensisextract. Furthermore, cell viabilities were more than 70% forG. uralensisextracts with concentrations of 50 and 100 mu g/mL. Naturally derivedG. uralensisis biocompatible and exhibits an excellent antimicrobial effect against oral pathogens such asS. mutansandC. albicans. Thus,G. uralensisextracts can be used for the development of oral products that treat and prevent oral diseases.