Dental caries which is induced by multiple factors is one of the most prevalent diseases in the world. Mutans streptococci，particularly Streptococcus sobrinus and Streptococcus mutans are considered as the primary causative agents of dental caries.
　The objective of this study is to evaluate the influence of extractive from leaves of Morus alba (ELM) and Salacia chinensis (ES) on production of insoluble glucan from sucrose by glucosyltransferase (GTase) of Streptococcus sobrinus 6715 and Streptococcus mutans MT8148 and the sucrose-dependent cell adhesion of S. sobrinus 6715.
　GTase of S. sobrinus 6715 was prepared from culture medium. GTase of S. mutans MT8148 was extracted from cell. In order to examine the inhibitory effect of ELM and ES on production of insoluble glucan byGTase，GTase solution， ¹⁴C-sucrose and ELM or ES were incubated at 37℃ for 24h. The influence of ELM and ES on sucrose-dependent cell adherence was evaluated by rate of cell adherent on smooth surface model. ELM and ES reduced the rate of production of insoluble glucan by GTase of S. sobrinus6715 to 66% and 30%，respectively，comparing with control. ELM and ES also reduced the rate of production of insoluble glucan that of S. mutans MT8148. Furthermore，ELM and ES reduced cell adhesion of S. sobrinus 6715，the rate of adhesion was 60% and 21%，respectively，comparing with control.
　These inhibitory effects of ES were stronger than ELM. These results suggest that ELM and ES are expected as anti-cariogenesis agents that reduce formation of dental plaque.