Objective To compare the antimicrobial activity of grape polyphenol（GP） and tea polyphenol（TP） on the growth of Streptococcus mutans（S.mutans）. Methods The antimicrobial activity was determined by the minimum inhibitory concentration（MIC） and the diameter of inhibition zone which resulted from the standard susceptibility agar dilution technique and the filter paper disks test respectively. Results Both GP and TP had antimicrobial activity on the growth of S.mutans. The diameter of the inhibition zone was between 0.5～7.2 mm and increased with the concentration. The MIC of GP against S.mutans was 1 g•L－1, while the MIC of TP was 0.5 g•L－1. Conclusion Both GP and TP could inhibit the growth of S.mutans. And the TP has a higher antimicrobial activity on the growth of S.mutans than GP, which could be applied in the development of oral health care products as a natural plant additiveto strengthen the effectiveness of caries prevention.
