Effects of thirty plant extracts on adhesion of Streptococcus mutans

Objective: To study the effects of thirty plant extracts on adhesion of Streptococcus mutans on saliva-coated hydroxyapatite powder. Methods: Thirty dried Thai plants were extracted with 95% methanol, evaporated and dissolved in 10% DMSO. The adhesion assay was performed in a 96-well plate by incubation of Streptococcus mutans ATCC25175 (10⁶ cfu/ml) with the saliva-coated hydroxyapatite powder in the presence or absence of 1.25 mg/ml plant extracts at 37 °C for 2 h. The adhered bacteria were detected by Alamar Blue fluorescent dye. The fluorescent intensity was measured by spectrofluorometer with excitation and emission at 570 nm and 585 nm, respectively. Results: Five extracts from Curcuma xanthorrhiza, Houttuynia cordata, Momordica charantia, Oxalis repens, and Zingiber cassumunar significantly reduced the adhesion of Streptococcus mutans to 58.33±11.39, 46.33±0.91, 50.76±13.85, 58.47±7.62 and 56.17±15.66%, respectively in comparison with the control DMSO. Conclusion: Curcuma xanthorrhiza, Houttuynia cordata, Momordica charantia, Oxalis repens, and Zingiber cassumunar may be used in caries prevention. Faculty of Dentistry, Chulalongkorn University Research Fund 2/2552