Comparison of phenolic, flavonoid compounds and antioxidative properties of Mentha spicata L. and Mentha longifolia L. 's extracts by different extraction methods

Spearmint (Mentha spicata L.) and Horsemint (Mentha longifolia L.) have abundant use in food expenses and Iranian Traditional Medicine. Tha aerial parts of both plants were collected and essential oil was isolated by hydrodistillation method (Clevenger). The extraction was conducted by maceration method (aqueous, hydroalcoholic and ethanolic solvents) and soxhlet method (ethanolic solvent). Total phenolic compounds content, Total flavonoid content, antioxidant capacity and free radical inhibition were measured. The results showed that total phenolic compounds and flavonoid content, total antioxidant capacity and percentage of free radical inhibition in applied extraction methods was different (P<0.05). The highest total phenolic compounds and flavonoid was obtained by soxhlet method in spearmint. The highest total antioxidant capacity were belong to hydroalcoholic extract in spearmint. Soxhlet extraction method is recommended because of its low processing cost, simplicity of operation, consume lesser time and solvent compared to other traditional methods such as soaking or percolation to extract phenolic compounds using other solvents. The use of a two-solvent system in the soaking process with other solvents requires further research to achieve high antioxidant properties.