Validation of use of a traditional remedy from Bridelia grandis (Pierre ex Hutch) stem bark against oral Streptococci.

Aim of the study: Bridelia grandis (Pierre ex Hutch) (Euphorbiaceae) is amedicinal plant traditionally used in Cameroon by pygmies Baka as a remedy for oral cavity affection. Bioassay-guided stem bark extracts were investigated for their in vitro antimicrobial properties as well as their phytochemical constituents. Materials and methods: The first extractionwas carried out according to the traditional use. Further extraction swere carried out with solvents of different polarity such as methanol (MeOH), ethyl acetate (EtOAc)and mixtures of MeOH–H2O. The antimicrobial activity of the extracts against oral Streptococci was evaluated on the basis of the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) by the macrodilution method; the bacterial surface hydrophobicity was also evaluated. Results: Water, methanol and mixtures methanol–water extracts, exhibited antibacterial activity with MIC between 0.5 and 2 mg/ml justifying the traditional use of Bridelia grandis stem bark for oral cavity affection. Preliminary phytochemical analysiswas performed on the most active extract (methanol) using appropriate tests and well established analytical screening methods, such as TLC and RP-HPLC/DAD.Conclusions: The data obtained indicate that tannins constitute the chemical family responsible for the biological activity.