The antioxidant activity of water, ethanol and methanol Hieracium pilosella L. extracts is reported. The antioxidative activity was tested by spectrophotometrically measuring their ability to scavenge a stable DPPH(•) free radical and a reactive hydroxyl radical trapped by DMPO during the Fenton reaction, using the ESR spectroscopy. Total phenolic content and total flavonoid content were evaluated according to the Folin-Ciocalteu procedure, and a colorimetric method, respectively. A HPLC method was used for identification of some phenolic compounds (chlorogenic acid, apigenin-7-O-glucoside and umbelliferone). The antioxidant activity of the investigated extracts slightly differs depending on the solvent used. The concentration of 0.30 mg/mL of water, ethanol and methanol extract is less effective in scavenging hydroxyl radicals (56.35, 58.73 and 54.35%, respectively) in comparison with the DPPH(•) radical scavenging activity (around 95% for all extracts). The high contents of total phenolic compounds (239.59-244.16 mg GAE/g of dry extract) and total flavonoids (79.13-82.18 mg RE/g of dry extract) indicated that these compounds contribute to the antioxidative activity.
Keywords: HPLC determination; Hieracium pilosella L. (Asteraceae); antioxidant activity; extraction; total flavonoids; total phenolic content.