Comprehensive Assessment of Antioxidant Activity of Essential Oils

Essential oils have been studied for their unique ability to act as antioxidants. Antioxidant activities of 423 essential oils of 48 different botanical families were evaluated for their antioxidant activities as free radical scavenging agents using the 1,1-diphenyl-2-picrylhydrazyl method. Seventy-three oils showed 50% or more inhibition at a concentration of 1.25 mg/mL. The 73 most active oil samples were further evaluated for their scavenging activities using series of dilutions to estimate their EC50. The EC50 of the 73 most active oils ranged from 4 to 2000 mu g/mL. Oils having an EC50 of less than 300 mu g/mL (20 selected samples) were subjected to beta-carotene bleaching antioxidant activity test and more detailed analysis including thin layer chromatography, gas chromatography/mass spectrometry, high performance liquid chromatography and bioautography. Essential oils of the botanical families Lamiaceae and Myrtaceae were the most effective antioxidants. Thymol and carvacrol were the major constituents in most of the essential oils of the family Lamiaceae and eugenol was the major terpene in all of the essential oils of the family Myrtaceae. Practical Applications: Supplementation of food with spices containing essential oils may counteract and retard the process of oxidative damage, lipid oxidation and elevate antioxidant activity of the final product.