A COMPARATIVE STUDY BETWEEN THREE ESSENTIAL OILS IN TERMS OF THEIR CHEMICAL COMPOSITION AND ANTIOXIDANT ACTIVITY

: The problem of oxidation and free radicals is one of the factors that are very dangerous to human health, which requires searching for safe natural compounds to be included in the diet and work to combat free radicals. The aim of this study was to evaluate the antioxidant effect of essential oils of basil, thyme and lemongrass by two different methods (FRAP and DPPH) as well as to identify the active ingredients of each oil by GCMS. The results of the fractionation on the GCMS showed that the main components of the essential oils were as follows: basil (L-linalool 59.02% and 1,8-cineole 9.52%), thyme (Thymol 48.06%and p-cymene 38.57%), and lemongrass (Geranial 47.59% and neral 36.27%). In the FRAP method, essential oil of basil was the strongest as an antioxidant (2.35± 0.61 mMol Fe +2 /g), followed by essential oil of thyme (1.96± 0.42 mMol Fe +2 /g), followed by essential oil of lemongrass by a large margin (0.93± 0.21 mMol Fe +2 /g). Whereas, when studying the antioxidant activity by the DPPH method, the results showed through comparison with IC 50 values that, basil essential oil was the strongest antioxidant (IC 50 =144.78 ± 7.19 μg/ml), followed by lemongrass essential oil (IC 50 =170.05 ± 6.97 μg/ml) and finally thyme essential oil (IC 50 =183.45 ± 7.19 μg/ml), w ith a slight difference. The results clearly indicated that the essential oil of basil was the best as an antioxidant compared to the essential oils of lemongrass and thyme in both methods used for the determination of antioxidant activity in vitro (FRAP and DPPH); this makes it a promising source of natural antioxidants that can be used in diets.