Volatile Constituents and Antioxidant Activity of Spathes from Five Uncommon Varieties of Phoenix dactylifera L.

Abstract

This study deals with characterization of chemical composition of spathe essential oil of five male varieties of Phoenix dactylifera L. including Ghir (GHI), Lar (LAR), Khosooyeh (KHO), Boyer (BOY) and Shahani (SHA). The essential oil samples were prepared through hydro-distillation using a Clevenger type apparatus. Analysis of oil samples was carried out following dehydration process. Hexane diluted samples were injected into a Gas chromatograph attached to a Mass spectrometer (GC/MS). Kovats indices (KI) was calculated for each compound and their mass fragmentation pattern were studied. The results compared with the relevant information procured from Wiley nl7 library and the Pherobase and NIST databases. Results of quantitative analysis of oil specimens indicated that, Ghir (0.03%) and Lar (0.07%) cultivars contain the lowest and the highest extraction yield of essential oil respectively. The oil samples were further screened for their DPPH free radical scavenging effects by means of a thin layer chromatographic method which showed a positive indication of anti DPPH activity through the visualization of spots and a yellow colour change on spraying the chromatoplates with a 0.2 % methanolic solution of DPPH. Results also indicated that 3,4-dimethoxytoluene is the main component in all Phoenix dactylifera L. spathe oil samples. This methoxylated aromatic compound showed the highest cocentration in Boyer (62.45%) and the lowest proportion in Khosooyeh cultivar (41.57%). Boyer spathe oil was superior in manifestation of DPPH free radical scavenging activity as compared with other cultivars.