Evaluation of antioxidant and antimicrobial activity of methanolic extract of Mentha Spicata leaves

Considering the undesirable side effects of synthetic antioxidants and antibiotics on human health and increasing the antibiotic resistance of pathogens, it is necessary to identify safe alternative sources for these compounds. In this study, antioxidant and antimicrobial activity of Mentha spicata methanolic extract were evaluated. The extract of leaves was prepared using Soxhlet extractor and methanol as solvent. The total phenol and flavonoid content were determined by folin-ciocalteu reagent and aluminum chloride colorimetric method, respectively. The antioxidant activity of M. spicata was determined via DPPH method. Also, the antimicrobial activity was evaluated by the agar well diffusion method and minimum inhibitory concentration (MIC) against various types of microorganisms. The extraction yield of M. spicata leaves was 22.60%. Also, the total phenol and flavonoid content were 278.537μg/mg dry weight of the extract in gallic acid equivalent and 75.579μg/mg dry weight of the extract, respectively. The IC50 of the methanolic extract of leaves and butylated hydroxytoluene were 61.243μg/ml and 19.8μg/ml, respectively. Based on the results of the agar well diffusion method and MIC, the most inhibitory effect of M. spicata extract was observed against Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, Klebsiella pneumonia and Staphylococcus aureus, respectively and had no effect on fungi. According to the results of this study, M. spicata extract has desired antioxidant and antimicrobial activity.