Phytochemical analysis and antioxidant activity of herbal plant Doronicum hookeri Hook f. (Asteraceae)

In this study, Doronicum hookeri Hook f. roots were extracted with two solvents of different polarity and evaluated for their in vitro antioxidant activities. Of the two extracts, methanolic extract possessed higher phenolic content and thus higher free radical scavenging and reducing activities. In DPPH (2,2-diphenyl-1-picryhydrazy) radical scavenging assay, methanolic extract showed scavenging similar to the standard BHT(butylated hydroxytoluene) (~85%) at concentration 0.5 mg/ml. Methanolic extract also exhibited more than 90% inhibition to ABTS radicals at concentration above 0.3 mg/ml. Reducing power activity of methanolic extract was also higher than dichloromethane extract. Dichloromethane extract was however rich in flavonoids and showed considerable metal chelating (78.684±0.659% at 0.5 mg/ml), nitric oxide (52.232±0.934% at 0.15 mg/ml) and superoxide radical (59.882±0.772% at 0.5 mg/ml) scavenging activities.   Key words: Antioxidant activity, Doronicum hookeri, ferric reducing antioxidant power, flavonoids, flavonol, metal chelating activity, nitric oxide radical scavenging, phenols, phytochemistry, superoxide radical scavenging.