We aimed to evaluate the antimicrobial effects of Glycyrrhiza uralensis extract on Streptococcus mutans and Candida albicans and its biocompatibility for dental applications. The antimicrobial activity of the G. uralensis extracts at concentrations of 50, 100, 150, and 200 µg/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 of G. uralensis extracts 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 that G. uralensis extracts had significant antimicrobial effects against S. mutans and C. albicans. The optical density of the experimental groups significantly decreased compared with that of the control group. SEM images revealed that the G. uralensis extract affected the morphology and density of S. mutans and C. albicans. The extract concentration of flavonoids, but not polyphenols, increased with increasing concentrations of the G. uralensis extract. Furthermore, cell viabilities were more than 70% for G. uralensis extracts with concentrations of 50 and 100 μg/mL. Naturally derived G. uralensis is biocompatible and exhibits an excellent antimicrobial effect against oral pathogens such as S. mutans and C. albicans. Thus, G. uralensis extracts can be used for the development of oral products that treat and prevent oral diseases.

Background and objectives: Bacterial antibiotics have had several side effects. Therefore, interest in natural substances with less side effects is increasing these days. Paeonia lactiflora, the root of Paeonia lactiflora, is used as a raw material for medicines. In this study, we investigated the antibacterial effect and the cytotoxicity of Paeonia lactiflora extract. Materials and Methods: For cytotoxicity, MTT analysis according to ISO 10993-5 was performed. The antibacterial test of the Paeonia lactiflora was determined from bacterial viability, Inhibition zone test, CFU (colony forming unit) and SEM (scanning electron microscope). To confirm the antibacterial component of Paeonia lactiflora, the content of flavonoids and polyphenols was analyzed. Results: Our results showed that Paeonia lactiflora extract contained flavonoids and polyphenols, which exhibited antimicrobial activity against Streptococcus mutans (S. mutans) and Candida albicans (C. ablicans). Further, the cytotoxicity of Paeonia lactiflora extract was low. Conclusions: We believe that our study makes a significant contribution to the literature because it demonstrates that Paeonia lactiflora extract can be used as an antibiotic.