Abstract
The essential oil (EO) of Xanthium strumarium L. leaves (family: Asteraceae) was extracted by hydrodistillation, and then analyzed by gas chromatography-mass spectrometry (GC-MS). Forty-three essential compounds were identified. The sesquiterpenoids represented the major constituents (72.4%), including oxygenated (61.78%) and non-oxygenated (10.62%) sesquiterpenes, followed by monoterpenes (25.19%). The diterpenoids and oxygenated hydrocarbons were determined as minor compounds. The main constituents of the EO were 1,5-dimethyltetralin (14.27%), eudesmol (10.60%), l-borneol (6.59%), ledene alcohol (6.46%), (-)-caryophyllene oxide (5.36%), isolongifolene, 7,8-dehydro-8a-hydroxy (5.06%), L-bornyl acetate (3.77%), and aristolene epoxide (3.58%). A comparative analysis was stated here between the EO of Egyptian X. strumarium and those previously reported from Pakistan, Iran, and Brazil based on chemometic tools such as principal components analysis (PCA) and agglomerative hierarchical clustering (AHC). The EO of X. strumarium showed weak 1, 1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity with IC50 321.93 mu L/L-1, which was comparable to ascorbic acid as a reference. However, the EO exhibited significant allelopathic potential regarding the germination and growth of the noxious weed Bidens pilosa in a concentration-dependent manner. Therefore, further study is recommended to characterize the EO from X. strumarium as an eco-friendly green bioherbicide against weeds, as well as determine their mode of actions.