Background
Prosopis africana is traditionally used in folk medicine in Burkina Faso for oral diseases. Leaves and stems are used in rural areas to treat dental caries, and the bark is used to treat green diarrhea in infants. In the context of a better understanding of Prosopis africana’s bioactivity and toxicity, the present study deals with the chemical profiling of the different botanical parts of P. Africana used in phytomedicine. The impact of herbal medicine on various factors contributing to oral infections and caries, specifically with its anti-biofilm and anti-quorum sensing properties have been little investigated.
Methods
The anti-biofilm effect of methanolic extracts of leaves and stems of P. africana was evaluated on Streptococcus mutans, Staphylococcus aureus, and Pseudomonas aeruginosa by using the crystal violet assay. The anti-quorum sensing effect on Chromobacterium CV026 and Pseudomonas aeruginosa was assessed spectrophotometrically by using the violacein, rhamnolipids and pyocyanin quantification assay. The cytotoxicity of the leaves and stems extracts was also evaluated by using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method. The chemical composition of the extracts was characterized by UPLC-UV/DAD-MS2/ESI-QTOF analysis.
Results
The extracts (100 µg/ml), without affecting cells viability, significantly reduced the biofilm formation of S. mutans with the best inhibition rates of 56.7% and 47.6% for stem and leaf extracts respectively. In Chromobacterium CV026, the violacein inhibition rate was 37.9 ± 3.7% for leaves methanol extract and 42.6 ± 1.4% for the stem methanol extract. In P. aeruginosa inhibition rates of 49.03%, 40.2%, and 46.7% were obtained for pyocyanin, elastase, and rhamnolipids respectively, with leaf extracts. UPLC-UV-MS2 analysis identified sixteen compounds which are mainly polyphenols and alkaloids. They could be related to the activities.
Conclusion
The present study provides evidence of the efficacy and basic scientific justification for the traditional uses of P. africana in the treatment of dental caries.

Prosopis africana, UPLC-UV/DAD-ESI-MS/MS, Anti-biofilm, Anti-quorum sensing, Dental care, Polyphenols, Alkaloids