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 a medicinal 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 extraction was carried out according to the traditional use. Further extractions were 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 analysis was 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.