Résumé
The present study was undertaken to evaluate the in vitro and in vivo antioxidant effects of different extracts prepared from the leaves of Xanthium strumarium. Polyphenols and flavonoids contents in all extracts were determined by spectrophotometric assays, antioxidant and antiradical capacities of the extracts were assayed using 2, 2-diphenyl-1-picrylhydrazyl radical (DPPH) radical scavenging assay, reducing power, β-carotene and anti-hemolytic assay. In addition, the in vivo antioxidant activity of three concentrations of leaves crude extract was investigated. Antioxidant activity of the crude extract was examined using anti-hemolytic assay and the determination of Glutathione and malondialdehyde (MDA) contents and catalase activity. In vitro antioxidant assays showed that crude extract and its fractions have strong effects in scavenging DPPH and reducing power. These activities decreased in the following order: ethyl acetate extract (EAE) > aqueous extract (AqE) > crude extract (CrE) > chloroform extract (ChE). The β-carotene bleaching assay showed that the CrE had the highest antioxidant activity followed by the EAE, AqE and the ChE. However, the anti-hemolytic test demonstrated that the ChE was the most effective in protecting red blood cells, followed by the EAE, AqE and the CrE. Three concentrations of leaves crude extract were tested for the in vivo antioxidant assays, and anti-hemolytic Catalase activity and the content of both MDA and Glutathione (GSH) were estimated. Among these tests, X. strumarium crude extract exhibited a potent inhibition of lipid peroxidation. It was concluded that X. strumarium extracts contain high phenolic content and have powerful antioxidant capacity in vitro and in vivo. These extracts were found to be safe with no toxic effects. These findings support the traditional use of this plant as an anti-inflammatory remedy.