eng Oriental Scientific Publishing Company Biomedical and Pharmacology Journal 0974-6242 2015-03-29 4 2 237 243 1933 article Keivan Saeb 1 Sara Gholamrezaee 1 Mahmoud Asadi 1 Department of Plant Biology, Tonekabon Branch, Islamic Azad University, Tonekabon (Iran). Plants rich source of phenolic compounds (phenolic acids, flavonoids and tannins) are the most important natural antioxidants. The Melissa officinalis has many valuable properties including antioxidant, anti-bacterial, analgesic, and relaxing. The purpose of this study was to determine change of antioxidant activity of plant leaves in various stage and the best harvest time of M.officinalis leaves for maximum antioxidant activity. Lemon balm leaves in three stages Different (vegetative growth stage, flowering stage and the stage after of flowering) collected and was dried. The antioxidant capacity of the plant extract done DPPH. The highest total phenolic and total flavonoids in leaves of plants and DPPH in flowering stage was high. So it seems the best time to plant, harvest leaves for the operation of its antioxidant property is in August. https://biomedpharmajournal.org/vol4no2/variation-of-antioxidant-activity-of-melissa-officinalis-leaves-extracts-during-the-different-stages-of-plant-growth/ Antioxidant activity M. officinalis FRAP assay Radical scavenging Flavonoids