Phytochemical analysis and antimicrobial potential of methanolic leaf extract of peppermint (Mentha piperita: Lamiaceae)

Abstract

The present investigation aims to assess the phytochemical content, antioxdative activity and antimicrobial activity of the methanolic leaf extract of locally available Mentha piperita, the mint plant. The methanolic leaf extract of mint leaves was analyzed qualitatively for the phytochemical contents as previously described. The 1,1-diphenyl-2-picrylhydrazyl–hydrate radical (DPPH) free radical scavenging assay was carried out with reference to butylated hydroxy toluene (BHT). The antimicrobial susceptibility test, including minimum inhibitory concentration and minimum bactericidal concentration (MIC and MBC) were determined. The functional chemical groups were determined by Fourier transform infrared spectroscopy (FTIR).The methanolic extract was found to contain tannins and flavanoids, with considerable free radical scavenging activity. The plant extract showed antimicrobial activity against clinical isolates of Escherichia coli, Acinetobacter, Staphylococcus aureus and two fungi such asCandida albicans, Candida glabrata. The FTIR results indicated the molecular configuration of different functional groups in the plant extract. The mint leaf methanolic extract showed considerable antibacterial and antifungal activity against selected bacteria and fungi. Regular intake of mint leaves presumed to ward-off the initial colonization of selected pathogenic microbes.   Key words: Mentha piperita, antimicrobial properties, Fourier transform infrared spectroscopy (FTIR).