Chemical Composition, Radical Scavenging and β-carotene Bleaching Assay of Essential Oils from Citrus aurantifolia, Citrus sinensis Peel, and Zataria multiflora Aerial Parts

Essential oil obtained from medicinal plants has been shown to have different biological activities and could replace chemical antioxidants to decrease oxidation of toxic chemical constituents and prevent disorders associated with oxidative damages. This study was aimed to evaluate chemical compositions and antioxidant activities of the essential oils obtained from Citrus aurantifolia (lime), Citrus sinensis (orange) peel, and Zataria multiflora aerial parts growing in Iran. The chemical composition and antioxidant activities of essential oils were examined using 2, 2-diphenyl-1- picrylhydrazyl (DPPH) scavenging activity and β-carotene bleaching methods. The results were compared with butylated hydroxyl toluene as a synthetic antioxidant. The chemical compositions of essential oils were analyzed with gas chromatography and mass spectrometry. Limonene (40.33%), β-pinene (9.45%), α-terpineol (10.88%), and γ-terpinolene (8.89%) were identified as the major compounds of the oil from C. aurantifolia peel. The main component in the oil of C. sinensis peel was limonene (90.492%), and thymol (38.67%), carvacrol (15.29%), p-cymene (10.23%), and γ-terpinene (9.75%) were the main components in the essential oil obtained from Z. multiflora. Z. multiflora essential oil showed potent antioxidant activity by DPPH (76%) and β-carotene bleaching (73.3%) methods. This study indicated that Z. multiflora essential oil exhibited the highest radical scavenging effect and could be used as an obtainable source of natural antioxidant.