Volatile oils, lipid constitutes and the antimicrobial activity of Daucus syrticus growing in Libya

ABSTRACT

Apiaceae is a large plant family; it comprises about 60 annual and biannual species mostly distributed in Europe, Africa, West Asia, and Australia. The Daucus genus is one of the most common genera of this family in which Daucus syrticus [DS] is a common member, growing mainly in the Sirt region [Libya]. It is locally known as wild carrot. This study aims to investigate volatile oils, lipid constitutes, and the antimicrobial activity of DS extracts. The herb of DS was collected from Wadi Telal, Sirt region [Libya], during January and April 2011. About 250 g of different parts from fresh plant material [aerial parts, roots, and seeds] of DS were subjected to hydrodistillation. Extraction of lipid constituents was carried out as follows About 1500 g of dried powdered plant material of DS were extracted with petroleum ether in a soxhlet. The antimicrobial activity was determined using the disk diffusion method, and the inhibition zone [IZ] was measured for each extract under study against Escherichia coli, Bacillus subtilis, Aspergillus niger, and Candida albicans. Results of Gas chromatography/Mass spectrometry GC/MS analyses of the volatile oils of the aerial parts [January and April collections] proved that they contain a mixture of 47 and 33 compounds, respectively, whereas the roots [April and July] were found to contain a mixture of 32 and 20 compounds, respectively. In addition, the seeds [July] were found to contain 18 compounds, with beta-asarone [26.23%] as the main compound. Investigation of the lipid fraction of the herb revealed the presence of a mixture of fatty alcohols; the major contents of the unsaponifiable fraction were identified as a series of n-alkanes C[8]-C[28] [84.85%], four steroidal compounds, triterpene, and a mixture of fatty acid methyl esters consisting of eight different acids. The antimicrobial evaluation of DS extracts exhibited different IZ values against the tested microorganisms. The main constituents of the different volatile oils of the aerial parts, the roots, and the seeds were identified. The fraction of total fatty acid had the highest activity against E. coli [IZ = 2.7, minimum inhibitory concentration = 250 mg/ml]