The Folin–Ciocâlteu phenol reagent 2N was purchased from Sigma-Aldrich (Buchs, Switzerland), and sodium carbonate decahydrate (Na2CO3·10H2O, M = 286.14) was from Chimopar S.A., Bucuresti, Romania. Methanol and gallic acid (97%, M = 170.12) were purchased from Sigma-Aldrich (Buchs, Switzerland).