Determination of antioxidant and radical scavenging activity of Inula helenium L. roots

The possible radical scavenging and antioxidant activity of two fractions of Inula helenium L. roots was investigated using different antioxidant methodologies: hydrogen peroxide-induced luminol chemiluminescence assay and DPPH free radical scavenging assay. Elecampane roots were extracted with methanol by maceration method and then the methanol extract was further partitioned with chloroform and ethyl acetate giving CHCl₃ and EtOAc fractions. Thin-layer chromatography analyses confirmed the presence of flavonoid aglycones in CHCl₃ fraction and a number of flavonoids and bitter principles in EtOAc fraction, as well as unidentified compounds. Total phenolic of these elecampane extracts was determinated by Folin-Ciocalteu method as the gallic acid equivalent and were to be 0.275% (CHCl₃) and 0.134% (EtOAc). At the 0.1mg/mL concentration, the scavenging effect were found to be 50.4% and 94%, respectively and decreased dose dependent to no inhibition for CHCl₃ fraction and 38.3% inhibition for EtOAc at 1µg/mL concentration. Quercetin was used as positive control. In adition, DPPH radical scavenging assay confirmed the antioxidant effect of both extracts and a rapid inhibition of the stable radical by EtOAc fraction was observed. The results concluded that the strong antioxidant effect of EtOAc elecampane fraction is not correlated with phenolic content, beeing probably traceable to bitter principles.