Effect of drying methods on yield, chemical composition and bioactivities of essential oil obtained from Moroccan Mentha pulegium L.

The effects of the drying methods on the composition, antioxidant, insecticidal and allelopathic properties of essential oils (EOs) obtained from the aerial parts of Moroccan Mentha pulegium L. were studied. The results indicated that drying methods used affect significantly the EOs yield of this species. The highest yield was obtained from aerial parts of M. pulegium dried in the shade (1.78 +/- 0.35%). The chemical composition analysis identified 14 components representing more than 93.4% of the total oils. Pulegone (57.8-62.8%), menthone (9.5-15.0%) and limonene (4.9-6.9%) were found to be the main constituents. Compared to the fresh samples, drying M. pulegium aerial parts with different treatments induced a slight increase in pulegone and menthone content and a parallel decrease of limonene. Drying methods enhanced the antioxidant activity of M. pulegium EOs especially those obtained from the aerial parts dried in Oven at 50 degrees C with IC50, values 6.82 +/- 0.18 mg/mL in DPPH assay and 22.68 +/- 0.87 mg/mL in reducing power assay. However, the treatments have no significant difference on the insecticidal and allelopathic properties of these oils. The results obtained in this study demonstrated that aerial parts of M. pulegium dried in the shade is the best optimal treatment to obtain the highest yield of EO, while drying this plant in oven at 50 degrees C is recommended to enhance the antioxidant potency of their EO for food and pharmaceutical applications.