Abstract

Putranjiva roxburghii, Conyza bonariensis, Woodfordia fruiticosa and Senecio chrysanthemoids were collected from different areas of Pakistan and extracted in methanol. The crude methanolic extract was dissolved in water and further partitioned with n-hexane, chloroform and n-butanol successively. Total phenols of all extracts were calculated using Folin-Ciocalteu (FC) reagent, while antioxidant activities were determined using standard protocols. All extracts contained reasonable amount of phenolic contents ranging from 36.9 ± 0.3 to 911.7 ± 1.4 mg GAE/g of extract, and maximum total phenols were present in the ethyl acetate extract of S. chrysanthemoids (911.7 ± 1.4 mg GAE/g of extract). Antiradical activity was measured as decrease in absorbance at 517 nm using diphenylpicrylhydrazyl radical (DPPH). The ethyl acetate extract of W. fruiticosa exhibited the highest activity (92.1 ± 1.6% with IC₅₀ = 4 ± 0 µg). The reducing potential of the extracts was determined with ferric reducing antioxidant power (FRAP) and total antioxidant capacity (TAC) assays. The ethyl acetate extract of C. bonariensis showed the highest activity in FRAP (671.9 ± 1.6 µM) and the extract of W. fruiticosa (ethyl acetate) was the most active (1.882 ± 0.041) in TAC among the other extracts of the selected medicinal plants.

Key words: DPPH, FRAP, TAC, medicinal plants.