Chemical Characterization and Antioxidative Activity of Mentha spicata L. (Lamiaceae) Essential Oil Depending on Harvesting Time

The objectives of this study were to evaluate chemical composition and the antioxidant activity of Mentha spicata essential oils from different phenophases. Essential oil content was from 1.67-2.02% v/w depends of phenophases. In total, 37, 34, and 36 compounds were identified in essential oils, including most dominant oxygenated monoterpenes (67.09-73.53%), monoterpene hydrocarbons (18.4-21.7%) and sesquiterpene hydrocarbons (5.21-8.73%). The major compound was carvone (53.79-57.98%). IC50 values of antioxidant activity of the essential oils range between 29.91-51.01 mu g/mL and the effectiveness was, in descending order: essential oil extracted before flowering stage > essential oil extracted in flowering stage > essential oil extracted after flowering stage. Antioxidant assays showed a significant correlation between the concentrations of the essential oil and percentage inhibition of free radicals. Results obtained in this study suggest the possible use of the essential oils for treating diseases related to free radicals.