The Scientific Basis of the Antibacterial Traditional Use of Calligonum comosum in UAE

Abstract Calligonum comosum L'Her. is an evergreen woody plant distributed throughout the temperate and arid regions of the Middle-East. The plant is used traditionally for skin infections and is reported to possess antibacterial activities. The antibacterial activity of the plant has been attributed to phytochemicals with a different polarity. However, the compounds essential for the antibacterial activity have not been identified yet. The plant is a known source of essential oil, yet, the biological activity of the essential oil has never been tested. In this study, the essential oil was extracted from the stems of the C. comosum plant growing in the United Arab Emirates (UAE) by steam distillation and analyzed by GC–MS. A total of 80 components were identified. The major component was 4-isopropylbenzaldehyde and represented 16 % of the total essential oil extracted. The essential oil showed significant antibacterial activities against Gram-negative E. coli and Gram-positive Staphylococcus aureus. A fractionation-based antibacterial assay indicated that the antibacterial activity of C. comosum was attributed to the presence of high amounts of 4-isopropylbenzaldehyde. Isopropylbenzaldehyde was not reported in essential oils obtained from plants growing in other regions, including the Kingdom of Saudi Arabia (KSA), and those from temperate regions. These results indicated that different climatic regions can significantly affect the chemistry and activities of medicinal plants of the same phenotype.