[Effects of glycyrrhizic acid on the growth and acid-producing of Streptococcus mutans in vitro].

OBJECTIVE: To investigate the antibacterial activity of glycyrrhizic acid against Streptococcus mutans (S. mutans, ATCC 25175) in vitro. METHODS: The minimal inhibitory concentration (MIC) and the minimal bactericidal concentration (MBC) of glycyrrhizic acid against S. mutans were detected using doubling dilution. The effects of glycyrrhizic acid on the growth and acidogenic profile of S. mutans and the inhibition ratio of glycyrrhizic acid on growth and acid-producing of S. mutans were investigated by detecting the Abs of bacteria suspension and the pH value of medium at definite time intervals (0 h, 3 h, 7 h, 12 h, 23 h, 40 h) during cultivation. RESULTS: The MIC determined for glycyrrhizic acid was 1.57 mg/mL and there was no bactericidal effect when concentration of glycyrrhizic acid up to 12.5 mg/mL. The glycyrrhizic acid inhibited the multiplication and acid-producing of S. mutans significantly and the effects became stronger with concentration increasing. When concentration up to 1.57 mg/mL, the inhibition ratio of glycyrrhizic acid on the growth and acid-producing of S. mutans were exceeded 80 and 70 percent, respectively. CONCLUSION: The glycyrrhizic acid can inhibit the growth and acid-producing of S. mutans in vitro.