Chemical composition of two essential oils extracted from Boswellia sacra and Juniperus excelsa gum-resins, respectively, were studied using infrared spectroscopy, gas chromatography-mass spectrometry (GC/MS) and GC-FID. Infrared analysis revealed the presence of CH, O-H, C=C and C=O functionality bonds. The GC-FID and GC/MS study showed the occurrence of 25 monoterpenes in each essential oil of which 18 (56.25 %) monoterpenes were shared by the two oils. The major component, α-pinene was detected in both oils with different proportion (80.50 % in J. excelsa gum oil versus 38.47 % in B. sacra gum oil). In addition, limonene present as a second major component (13.36 %) in B. sacra oil, but it was detected in very low amount in J. excelsa oil (2.46 %). Sesquiterpenes exist in B. sacra gum-resin oil only. Essential oil of B. sacra gum-resin showed stronger antioxidant activity than J. excelsa gum-resin oil, but both oils showed lower antioxidant activity compared to ascorbic acid.
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