Antimicrobial Activities of S. Baicalensis Extract

Objectives: The purpose of the present study was to determine whether sub-MIC concentration of Scutellaria baicalensis Georigi (huangqin) extract could affect some of the cariogenic properties of oral streptococci. Methods: Oral streptococci (S. mutans ATCC2517, S. sobrinus ATCC33478 and S. salivarius ATCC7073) were our main test organisms. Standard physiologic assays were used to assess inhibitory action of Scutellaria baicalensis Georigi (70%Ethanolic crude extract). Antibacterial assay MBC, MIC and sub-MIC was determined by broth dilution method and an agar dilution method. The time kill cure method was used to study the bactericidal effect of Scutellaria baicalensis Georigi extract. Cell-surface hydrophobicity of S. mutans was measured using the MATH test. Results: All streptococci were susceptible to 70% Ethanolic crude extract of Scutellaria baicalensis Georigi with minimum bactericidal concentration (MBC) values of 1.0 mg/ml. Minimum inhibitory concentration (MIC) values were 0.5-0.25 mg/ml. Subinhibition concentration (Sub-MIC) values of 0.25-0.0625 mg/ml reduced the cell-surface hydrophobicity and the adherence of streptococci (almost 80%) to glass surface. Conclusions: Our data support the hypothesis that in vitro, the biological activity of Scutellaria baicalensis Georigi (70% Ethanolic extract) at sub-MIC concentration can interfere with hydrophobicity and adhesion of oral streptococci. Further studies are worth performing to evaluate their effect in vivo.