Streptococcus mutans (S. mutans) has virulence factors involved in the pathogenesis of dental caries. The aim of this study was to investigate the inhibitory effects of the crude water extracts from Musa sapientum inflorescence (MSI water extract) on S. mutans. Minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were determined by the broth microdilution method. In addition, the inhibitory effects on glycosyltransferase activity (GTFs) of S. mutans, biofilm formation, and acid production were examined. The MIC and MBC of MSI water extract were 62.5 and 125 mg/ml, respectively, tested with 0.05% v/v chlorhexidine as the positive control. At 2MIC, the viability of S. mutans was reduced by at least 2.3 log CFU/ml compared with the positive control. MSI water extract at MIC and sub-MIC showed more than 50 percent inhibitory effect on GTFs. MSI water extracts at 1/2MIC, 1/4MIC and 1/8MIC exhibited attenuation of the acid production in a dosedependent manner. This results indicate that MSI water extract exhibits inhibitory effects on virulence factors of S. mutans.
