ABSTRACT
In recent years, natural products, especially natural antioxidants, play an important role in various fields. In fact, Lippia citriodora is one of the medicinal plants which is cultivated in Iran and it may be has potential antioxidant activity. The chemical composition of Lippia citriodora essential oil [LCEO] has been determined. The total phenolic content and antioxidative properties of LCEO were determined. Finally, the effect of the thermal treatment [80, 120, 180°C] for 1, 2 and 3 hours on the antioxidant activity [AOA] and the chemical composition of LCEO were studied. The unheated and heated LCEO components were identified by GC/MS. The antioxidant activity [AOA] of LCEO was determined by two complementary test methods, namely DPPH free radical-scavenging and beta -carotene bleaching. LCEO had different chemical components such as R-curcumene [14.1%], caryophyllene oxide [6.6%], 6-methyl-5-hepten-2-one [7.1%], and spathulenol [7.0%]. The IC50 of LCEO was compared with that of synthetic antioxidant [BHT]. Antioxidant activities of LCEO at different concentrations [0.6- 2.5 mg/ml] were determined by beta -carotene bleaching method. The antioxidant activities of LCEO at this range of concentrations were 1.5 - 68.0%. After heating up to 180°C, the essential oil showed a significantly higher free radical-scavenger activity and evident changes in its chemical composition. The study can be further extended to exploit not only the phenolic extracts but also the residual phenolic constituents associated with this herbal medicine as health supplement
ABSTRACT
Thymus daenensis Celak. Is one of the medicinal plants which cultivated in Iran. This plant involve high amount of polyphenols including thymol and carvacrol, which were reported to possess the high antioxidant activity. Antioxidative activity [AOA] and chemical constituents of Thymus daenensis essential oil [TDEO] were examined. Also, the effect of thermal treatments [80,120 and 180°C] for 1, 2 and 3 hours on the AOA and chemical constituents of TDEO was studied. The chemical constituents of Thymus daenensis essential oil was analyzed by GC/MS. Antioxidant activity [AOA] of TDEO was determined by two complementary test methods, namely DPPH free radical-scavenging and beta -carotene bleaching. TDEO had different chemical components, including thymol [54.7%], carvacrol [5.0%], linalool [1.9%], 1-octene-3-ol [1.6%], p-cymene [11.3%], terpin-4-ol [1.5%], gamma-terpinene [12.9%], alpha -terpinene [2.0%], myrcene [1.1%], beta -caryophelene [2.6%] and borneol [1.1%]. The IC[50] of TDEO was compared with synthetic antioxidant [BHT]. Antioxidant activities of TDEO at different concentrations [0.1- 3.1 mg/ml] were determined by beta -carotene bleaching method. Antioxidant activity of TDEO at these range of concentration were 20 - 96.0%. After heating up to 180°C, essential oil showed a significantly higher free radical-scavenger activity and evident changes in its chemical composition. Owing to this property, the studies can be further extended to exploit not only the phenolic extracts but also the residual phenolic constituents associated with this herbal medicine as health supplement and nutraceutical