Antioxidant and antibacterial properties of the Melissa officinalis essential oil

Background: Increasing drug resistance in microorganisms and concerns for side effects of chemical preservatives, especially in the food industry, have led to extensive studies on novel potential agents with natural origin. Objective: The aim of this study was to determine the antioxidant and antibacterial properties of the Melissa officinalis essential oil. Methods: This experimental study was carried out at Islamic Azad University, Saveh Branch in 2012-2013. The essential oil was extracted from different parts of the plant (leaves, stem and flower) by hydrodistillation. The essential oil was phytochemically characterized by gas chromatography-mass spectrometry (GC-MS) analysis. Antibacterial properties were examined by disc diffusion and microtiter plates. Antioxidant activity was examined by diphenyl-picryl-hydrazyl (DPPH) assay. Findings: E-Citral in leaves, 2-Cyclohexen-1-one, 2-methyl-5-(1-methylethenyl) in stem, and Trans-Carveol in flower were the major components identified in the Melissa officinalis. Among different parts essential oil, the highest and the lowest antibacterial activity were related to leaves and stem, respectively.  The largest diameter of the inhibition growth zone for Staphylococcus aureus and Pseudomonas aeruginosa was related to the leaves essential oil. The highest antioxidant activity was related to the leaves essential oil in DPPH assay. Conclusion: With regards to the results, the Melissa officinalis essential oil can be used as a natural preservative for increasing the shelf life of foods.