Abstract:
M. piperita (Lamiaceae family) have been used as traditional remedies for the treatment of several diseases. In this work, we aimed to characterize the antimicrobial activity of extracts of Mentha piperita leaves. Various extracts (methanolic and aqueous) were analysed for their phenolic content and antimicrobial activity. This was done by the method of diffusion against three Gram+ (Staphylococcus aureus ATCC 25923, Methicillin-resistant Staphylococcus aureus (MRSA) ATCC 43300 and Bacillus subtilis ATCC6633) and three Gram- (Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922 and Salmonella typhi ATCC 14028) strains and a yeast (C. albicans ATCC 1024). On the other hand, the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of active extracts; were determined by using the dilution method on solid medium. The results indicate that the leaves extracts are rich in polyphénols. On the other side, the Antimicrobial tests exhibited different activities depending on the strain used and the nature of the extract (methanol or aqueous). MRSA was the most sensitive since its growth was inhibited by both extracts with the widest diameter of 23.5mm, whereas Gram-negative bacteria and the yeast C. albicans were the most resistant. The results of the MIC and the MBC of active extracts showed that both extracts (methanolic and aqueous) of leaves showed the best activity against SARM (MIC: 8mg/ml; MBC: 10mg/ml). Determination of total phenols and flavonoids suggested that the antibacterial activity is attributed mainly to the richness of this plant in phenolic compounds. These preliminary results may justify the use of this plant in the treatment of certain bacterial diseases and that phenolic compounds may be exploited for therapeutic purposes, especially antibacterial.

Keywords: Antimicrobial Activity, Mentha piperita, Phenolic Compounds, MIC, MBC.