The concentration of TPC in different extracts was measured using UV spectrophotometer (Jenway-UV–VIS Spectrophotometer),based on a colorimetric oxidation/reduction reaction,as described by Sˇ kerget et al. (2005) using FolinCiocalteu reagent. Specifically, 0.5 mL of diluted extract
(10 mg in 10 mL solvent) was mixed with 2.5 mL of Folin–Ciocalteureagent (diluted 10 times with distilled water) and 2 mL of Na2CO3 (75 g/1 L).