Phenolic acid content, antiradical and antimicrobial properties of Mentha aquatica leaf methanolic extract

Mentha aquatica is an important species of the family Labiatae that is commonly grown in the north of Iran. This study evaluated the in vitro potential of antioxidant and antimicrobial activity and analyzed the constituent phenolic acid in the methanolic extract of M. aquatica leaves as a traditional medicinal plant. The total phenolic content of the methanolic extract of M. aquatica was determined using the Folin-Ciocalteu method and antimicrobial activity by broth microdilution and determination of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). High-performance liquid chromatography was used to determine the phenolic acid content of the extract. A DPPH radical scavenging assay was used to characterize antioxidant activity. The methanolic extract of M. aquatica showed excellent antioxidant activity at all concentrations (50، 100، 150، 200 μg/ml). The DPPH activity of the extract increased in a dose dependent manner for a range of 26. 46–87. 23%. The extract also revealed good antimicrobial activity against the four tested bacteria (Bacillus cereus، Staphylococcus aureus، Escherichia coli، Salmonella enterica). The most efficient bactericidal activity of the extract was against Salmonella enteric at MBC=2. 5 mg/ml and Escherichia coli was the strongest bacterium (MBC = 40 mg/ml). Analysis of the phenolic acid content in the leaves showed that chlorogenic acid (732. 84 μg/g dw) was a predominant compound. The methanolic extract of the M. aquatica leaves can be used in place of chemical substances to control bacterial growth and increase the shelf- life of food.