P.betle and S.aromaticum - Effect on the acid-producing activity of S.mutans

It has been reported that both the P. betle (betel leaves)and S. aromaticum (clove)extracts have antibacterial activity towards Streptococcus mutans. However, there were no reports to date on the comparison of the effectiveness between the two extracts. Objectives: The purpose of this study was to compare the effect of crude aqueous P. betle leaves and S. aromaticum extracts on the growth and acid producing activity of Streptococcus mutans ATCC 25175. Methods: Crude aqueous P. betle leaves (PA) and clove extracts (ClA) were prepared by decoction. The effect of the extracts on the growth of S. mutans was determined from the number of bacterial cells grown in BHI broth in the presence of the extracts. Acid producing activity of the bacteria was analysed by pH drop assay. Results: Both the ClA and PA extracts showed inhibitory effect towards growth and acid producing activity of S. mutans. The inhibitory effect increases as the concentration of the extract increases. The PA extract showed better inhibitory effect towards growth of S. mutans at higher concentrations. At 10 mg/ml, the PA extract inhibited growth by almost 99 % whereas the ClA extract exhibited about 70 % inhibition. At this concentration, the CIA extract showed 30% reduction in acid producing activity, whereas the PA extract was more than 75% reduction. These inhibitory effects of the extracts may suggest its potential role in the prevention of dental caries. Conclusions: The PA extract showed a more potent inhibitory effect on the growth and acid producing activity of Streptococcus mutans compared with the ClA extract.