Comparative Antioxidant Activity and Volatile Oil Composition of Leaves and Fruits of Thuja orientalis Growing in Egypt

Thuja orientalis L. (Cupressaceae) is an evergreen arbor that is distributed throughout Northeast Asia as a common ornamental plant. The volatile oil of leaves and fruits of T. orientalis growing in Egypt was prepared by hydro-distillation followed by GC-MS analysis in order to compare between their compositions. Results revealed that fruits are richer in monoterpenes (62.5 %) while leaves are richer in sesquiterpenes (57 %). The major components in leaf oil are; α-cedrol (15.8 %), β-caryophyllene (15 %), α-humulene (10.7 %), d-limonene (7.3 %), α-pinene (6.9 %), β-myrecene (5.9 %) and α-terpinolene (5.2 %). On the other hand, fruit oil contains α-pinene (11.3 %), α-cedrol (11.2 %), β-myrecene (9.6 %), geranyl acetate (9 %) and β-caryophyllene (8.9 %) in major amounts. Comparison between the oil content in the Egyptian conifer and other reported conifers worldwide is also discussed. Comparative determination of total phenolic content (TPC), total flavonoids content (TFC) and anti-oxidant activity of alcoholic extract of both leaves and fruits showed that fruits content of flavonoids (0.6267±0.026 mg RE /g) is double the content of the leaves (0.3069±0.019 mg RE /g). Similarly, fruits contain higher phenolic content (0.75±0.007 mg GE/g) compared to 0.51±0.007 mg GE/g in leaves. Also, fruits extract exhibited higher anti-oxidant activity (2.3516±0.0 mg AEAC/g) than leaves (1.2734±0.0022 mg AEAC/g). The extracts of T. orientalis could be a valuable material for pharmaceutical industry.