Phytochemical Screening, In-vitro Evaluation of Antioxidant and Free Radical Scavenging Activity of Leaves, Stems and Roots of Xanthium strumarium L., (Compositae)

Introduction: Many diseases are associated with oxidative stress caused by free radicals. Current research is directed towards finding naturally occurring antioxidants of plant origin. Xanthium strumarium L. a cocklebur or bur weed is a reputed medicine in Europe, China, Indo-china, Malaysia and America. It is used in treatment of common disease such as hemicrania, leucoderma, biliousness, poisonous bites of insects, epilepsy, long standing malaria, relieving constipation, diarrhoea, vomiting etc. The present research deals with phytochemical screening and in-vitro evaluation of antioxidant activities of the various extracts of leaves, stems and roots of X. strumarium L.
Method: Successive extracts of leaves, stems and roots was subjected for phytochemical screening. Various extracts of leaves, stems and roots were screened in-vitro for total antioxidant potential. Inhibition of oxygen derived free radicals, viz., assay for free radical scavenging of nitric oxide, hydrogen peroxide, the antioxidant capacity by phosphomolybdenum, reducing power ability and determination of phenolic and flavonoids content in the extracts of leaves, stems and roots were performed. DPPH scavenging activity or the Hydrogen donating capacity was quantified in presence of stable DPPH radical on the basis of Blois method. NO scavenging activity was performed in the presence of nitric oxide generated from sodium nitroprusside using ascorbic acid as standard in both methods. The phenolic content was determined by using Folin-Ciocalteu reagent and flavonoid content was determined by aluminium chloride.
Result: The preliminary phytochemical screening revealed the presence of saponins, sterols, flavonoids, alkaloids and phenolic compounds in the extracts. The scavenging activity was found to be dose dependent. The reducing capacity serves as significant indicator of antioxidant activity. The reducing power increased with the increasing concentration of sample. The 100mg powder of leaves yielded 0.069, 0.523, 1.620 mg/g phenolic content and 0.17, 0.45, 0.95 mg/g flavonoid content with solvents such as petroleum ether (60º-80ºc), chloroform, and ethanol respectively. Similarly, in case of stems and roots the phenolic content yielded 0.063, 0.324, 1.324 mg/g and 0.040, 0.159, 0.41 mg/g and flavonoids content 0.00, 0.11, 0.23 mg/g and 0.00, 0.05, 0.18 mg/g respectively, using quercetin as standard.
Conclusion: The present study provides evidence that X. strumarium L., is a potential source of antioxidants and the extracts have constituents which were capable of showing antioxidant activity and the said in-vitro antioxidant activity may also be due to the presence of antioxidant principles present in the extracts like flavonoid and phenolic compounds. So the folklore use of X. strumarium L. has been proved in present research work. These findings confirm the great interest of the herb whose phytochemistry and phytopharmacology should be investigated further in order to detect possible phytotherapeutic uses in the prevention of ageing related diseases, cardiovascular disorders and Alzheimer disease.