Optimization of Piper sarmentosum Extract Concentration and Exposure Time to Inhibit Biofilm Formation of Dental Plaque-Causing Bacteria

Streptococcus mutans and Streptococcus sobrinus are the primary oral pathogens that can lead to the formation of dental plaque. Piper sarmentosum is a medicinal plant has the potential alternative solution to solve the problem. The objectives of this project were to optimize the extraction concentration, total phenolic compounds (TPC) and total flavonoid compounds (TFC) in P. sarmentosum by using 80% methanol and 95% ethanol as the extraction solvents and the exposure time of the extract of P. sarmentosum to inhibit the biofilm formation of both S. mutans and S. sobrinus. The extract with higher TPC and TFC was screened by using GC-MS analysis. The minimum inhibitory concentration (MIC) of the plant extract against the oral pathogen was determined by using an MTT colourimetric assay. The anti-adherence and biofilm-inhibitory assays were performed when the exposure time of the plant extract towards the oral pathogen reached 1, 3, 6 and 24 hours. The 80% methanolic extract exerts a higher ability to extract more phenolic and flavonoid compounds compared with 95% ethanol as the extraction solvent. The MIC of the 80% methanolic extract towards S. mutans and S. sobrinus was 50 mg/mL and 100 mg/mL, respectively. A dose-dependent manner was observed in both anti-adherence and biofilm inhibitory assays. The best biofilm-inhibitory activity was observed when the exposure time of the plant extract towards the oral pathogen reached 1 hour. These findings served as preliminary ideas about the potential of P. sarmentosum to develop into oral care products.