Synergistic Antioxidant Activity and Chemical Composition of Essential Oils From Thymus fontanesii, Artemisia herba-alba and Rosmarinus officinalis

Introduction: Oxidative stress is involved in many pathological mechanisms especially those due to aging, such as cancer, Parkinson’s and Alzheimer’s disease. Essential oils are known for their biological properties, especially as anti-nociceptive, anticancer, antiviral and antioxidative. The main objective of this study was to study the antioxidant activity of essential oils from Thymus fontanesii, Artemisia herba-alba and Rosmarinus officinalis, individually and in combinations. Materials and Methods: Essential oils of plants aerial parts were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC/MS). The antioxidant properties were evaluated using two different methods, α, α-diphenyl-β-picrylhydrazyl (DPPH) radical scavenging activity and ferric reducing antioxidant power (FRAP). Results: The essential oil of T. fontanesii was principally characterized by phenolic compounds represented by thymol (76.6%) and p-cymene (7.4%). The constituents identified from A. herba-alba essential oil were principally represented by camphor (32.3%) and chrysanthenone (25.6%). While, R. officinalis essential oil was characterized by 1,8-cineole (18.3%), camphene (15.4%) and α-pinene (12.8%). T. fontanesii essential oil indicated the significantly highest activity in quenching of DPPH radical, followed by R. officinalis and A. herba-alba essential oils with IC50 of 13.7, 24.5 and 79.4 mg/L, respectively. The combination of T. fontanesii, A. herba-alba and R. officinalis essential oils showed the greatest antioxidant activity with an IC50 of 2.6 mg/L almost equal to the synthetic antioxidant butylated hydroxytoluene (BHT). Conclusions: The essential oils blend presented high antioxidant activity compared to individual oils. These findings provide a new source of antioxidant that can be used as a natural food preservative and alternative to chemical synthetic preservatives.