In vitro antioxidant potentials and chemistry of essential oils and oleoresins from fresh and sun-dried Mentha longifolia L.

The present study was designed to assess differences in chemical composition and antioxidant potential of essential oils and oleoresins from fresh and sun-dried Mentha longifolia L. Essential oils and oleoresins were obtained by hydrodistillation and solvent extraction (n-hexane and ethanol), respectively. The chemical profile was evaluated by using gas chromatography (GC) and GC coupled to mass spectrometry (GC–MS). Antioxidant effectiveness was examined by five different methods, namely the ferric thiocyanate (FTC) method, the 2,2’-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method, determination of the metal chelating power, and determination of the peroxide and thiobarbituric acid values in mustard oil at 0.02% concentration. The chemical composition was dominated by the presence of piperitenone oxide, an oxygenated monoterpene whose composition varied from 23.2% to 88.5% in both essential oils and oleoresins. Based on the antioxidant potential of essential oils, oleoresins and synthetic antio...