甘草水煎剂对变异链球菌生长和产酸影响的体外研究

目的研究甘草水煎剂对体外培养的变异链球菌的抗菌活性。方法取粒径为0.2～3.2 mm的甘草颗粒加去离子水煎煮后过滤，滤液为实验用甘草水煎剂。采用液体稀释法测定甘草水煎剂对变异链球菌的最低抑菌浓度（MIC）和最低杀菌浓度（MBC）。在不同浓度甘草水煎剂中培养变异链球菌，分别于培养0﹑3﹑7﹑12﹑23、40 h时测定细菌悬液光密度值和培养液pH值，绘制变异链球菌的生长曲线和产酸曲线。结果甘草水煎剂对变异链球菌的MIC为50 mg·mL-1，浓度小于等于100 mg·mL-1的甘草水煎剂对变异链球菌无杀菌作用。甘草水煎剂对变异链球菌生长的抑制作用随浓度的增加而增强。甘草水煎剂对变异链球菌的产酸有一定的抑制作用，在培养12 h时抑制作用最强。结论甘草水煎剂对体外培养的变异链球菌生长和产酸均有抑制作用。

Effect of decoction of Radix glycyrrhizae on the growth and acid-production of Streptococcus mutants in vitro

Objective To investigate the antibacterial activity of decoction of Radix glycyrrhizae against Streptococcus mutans（S.mutans） in vitro. Methods The decoction of Radix glycyrrhizae was prepared by boiling particles of Radix glycyrrhizae, the diameter was 0.2-3.2 mm. In distilled water and filtered, the filtrate was collected for study. The minimal inhibitory concentration（MIC） and the minimal bactericidal concentration（MBC） of the decoction against S.mutans were detected using double dilution. The effect of decoction on growth and acidogenic profile of S. mutans were investigated by detecting the Abs of bacteria suspension and the pH value of medium at definite time intervals（0, 3, 7, 12, 23, 40 h） during cultured. Results The MIC determined for decoction was 50 mg·mL-1 and there was no bactericidal effect when concentration of decoction lower than 100 mg·mL-1. The decoction inhibitted multiplication of bacteria significantly and the effects became stronger with concentration increasing. The decoction also inhibitted S.mutans producing acid and the effect became stronger with concentration increasing. The most efficient inhibition were observed when incubated 12 hours. Conclusion The decoction of Radix glycyrrhizae can inhibite the growth and acid-production of S.mutans in vitro.