Evaluation of antioxidant activity and phytochemical composition of Baeckea frutescens and Leptospermum javanicum essential oils

Abstract Plant extracts such as essential oils are a common yet valuable source of antioxidants for application in pharmaceutical and food preservative. In this study, the phytochemical profile of Baeckea frutescens (BF) and Leptospermum javanicum (LJ) essential oils were determined using GC-FID and GC/MS analyses. This resulted in the identification of 13 components (82.03%) in the essential oil of BF, the major compounds were p-cymene (1, 31.06%), α-pinene (2, 24.53%), 1,8-cineole (3, 11.49%), and γ-terpinene (4, 8.31%). Whilst, 32 components (84.62%) were detected in the essential oil of LJ, in which sabinene (5, 25.83%) and α-pinene (2, 12.17%) were the major components. The antioxidant activity of the essential oils were evaluated using a wide array of radical scavenging assays, such as DPPH radical scavenging, reducing power, metal chelating, and β-carotene bleaching assays. From the results, both BF and LJ essential oils exhibited appreciable antioxidant activity in all assays (EC50 0.29–1.39 mg/mL), except in DPPH radical scavenging assay (EC50 > 50 mg/mL). The essential oil of BF had a higher overall antioxidant capacity than LJ. With reference to the phytochemical profile, compounds 1–5 are potent antioxidants, which may substantially contribute to the antioxidant capacity of the essential oils.