Antioxidant Activity and Total Phenolic and Flavonoid Contents of Hieracium pilosella L. Extracts

Abstract

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.

Figure 1.

ESR spectra of DMPO-OH spin adducts: with no addition of extracts (blank) (a); the same as blank but with 0.3 mg/mL DMF solution of aqueous (b), ethanolic (c) and methanolic extract (d).

Figure 2.

Antioxidant activity of different concentrations of aqueous, ethanolic and methanolic extracts of Hieracium pilosella L. on hydroxyl radical.

Figure 3.

The antioxidant activity of different concentrations of aqueous (a), ethanolic (b) and methanolic (c) extract of Hieracium pilosella L. on DPPH radicals; (–□–) without incubation; (–○–) 20 min of incubation.