Influence of Heating on Antiradical Activity of Essential Oils of Thyme, Summer Savory and Clove by 2, 2- Diphenyl-1-Picrylhydrazyl (DPPH") Method

Great interest has recently been focused on the addition of herbs and their derivatives to foods and biological systems, due to their well-known abilities to scavenge free radicals. For this reason, the antiradical activities of essential oils of thyme (Thymus vulgaris L.), summer savory (Satureja hortensis L.) and clove (Syzygium aromaticum L.) were studied. The essential oils of these medicinal plants were analyzed by GC/MS and the major chemical components were identified. Also, antiradical activities of these essential oils were evaluated by using DPPH radical. Samples were kept at 120 and 180ºC for 0.5, 1, 2, and 3 hours to evaluate the influence of heating on the essential oils, then compared with controls (essential oils before heat treatment). Results showed that clove oil had the highest antiradical activity and followed by summer savory and thyme oil, respectively. The essential oils showed various behaviors under different treatments of heating. All tested essential oils had radical scavenging activities at room temperature. These essential oils showed various behaviors under different heat treatments which it may be due to their different compositions.