Comparison between the chemical composition and radical scavenging activities of essential oils of leaves, flowers and fruits of Callistemon lanceolatus DC grown in Egypt

The essential oils obtained by hydrodistillation from leaves, flowers and fruits of Callistemon lanceolatus were analyzed by GC/MS. The oil yields were 0.68%, 0.52% and 0.25%, respectively. Thirty six compounds were identified in leaf oil, while thirty four compounds were identified in both the flower and fruit oils. 1,8-Cineole was the main component in the three oils in percentage 87.8% in leaf oil, 73.8% in flower oil and 40. 9% in fruit oil, followed by p-menth-1-en-8-ol which present in higher percentage in fruit oil (4.3%) than in leaf oil (2.9%). The flower oil was characterized by its high content of alpha -pinene (27.2%) and cis-asarone (9.7%).

In vitro radical scavenging activities of these oils obtained by DPPH (2, 2-diphenyl-1-picrylhydrazyl) assay, were also evaluated between 5 and 20mg/ml. At 20mg/ml, leaf, fruit and flower oils showed good capacities to act as a non specific donor of hydrogen atoms or electrons, quenching 91.6, 71.5 and 52% of the radicals, respectively. The IC₅₀ values of the oils were 7.6, 11.8 and 19.1mg/ml, respectively.

References: [1] Guenther, E. (1961). The Essential Oils, Vol VI, Van Nostrand, NewYork. [2] Adams, R. P. (1995). Identification of Essential Oils Components by Gas Chromatography/Mass Spectrometry. Allured Publication, Carol Stream, Illinois. [3] Calliste, C. A. et al. (2001). J. Agr. Food Chem. 49: 3321–3327.