The effect of the extraction techniques on the kinetics, yield and antioxidative activity of ethyl acetate extracts of Hieracium pilosella L.

The influence of three extraction techniques (Reflux maceration, Soxhlet and Tillepape extraction) on the kinetics, yield and antioxidant activity of ethyl acetate extracts of Hieracium pilosella L. was investigated. The antioxidant activity of the extracts on stable 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical was determined spectrophotometrically. The total phenolic content was determined by using the Folin-Ciocalteu assay and the total flavonoids content was measured by spectrophotometric method with the application of AlCl3. The extraction kinetics models (extraction by maceration, Tillepepe and Soxhlet extraction) for the extraction of total extractive matter were defined: model Ponomaryov (A) and non-stationary diffusion model (B). The highest yield of a dry extract was obtained by Soxhlet extraction, for a time period of 240 minutes. In the extracts a high content of total phenolics and flavonoids was determined. The antioxidant activity of the investigated extracts slightly differs depending on the extraction technique applied. The extract obtained by the Soxhlet extraction contained higher amounts of phenolic and flavonoid compounds and showed a better antioxidant activity than those obtained by maceration with reflux and Tillepape extraction. The obtained results show that the ethyl acetate extracts of Hieracium pilosella L. can be used as natural antioxidants.