Determination of total phenols
Total phenol content was determined following the Folin-Ciocalteau method (Atanassova, Georgieva & Ivancheva 2011). Briefly, 200 μL of sample or standard solution of gallic acid was mixed with 1.4 mL deionized water and 100 μL Folin-Ciocalteau´s phenol reagent (2 mol L-1; Sigma Aldrich; Italy). Total phenol content was determined using a spectrophotometer (Agilent Technologies, Cary Series 100 UV-VIS Spectrophotometer, Italy) to measure the absorbance at 765 nm, then expressing the results as µmol of gallic acid equivalent.