Luteolinidin chloride

Folin-Ciocalteu reagent, gallic acid, catechin hydrate, Trolox, ethanolamine, were obtained from Sigma-Aldrich (St. Louis, MO, USA). Luteolinidin chloride, apigeninidin chloride and 7-methoxy-apigeninidin were obtained from ChromaDex (Santa Ana, CA, USA). sec-Butanol was reagent grade and all other solvents were HPLC grade.

Ethanol p.a, hydrochloric acid (370 g·L⁻¹), iron (II) sulphate heptahydrate, iron (III) chloride hexahydrate, sodium acetate trihydrate, were purchased from Merck (Darmstadt, Germany). Folin–Ciocalteu reagent, and potassium hexacyanoferrate (III), gallic acid (990 g·L⁻¹) were purchased from Sigma (Sternheim, Germany). Sodium carbonate anhydrous was obtained from BDH (Poole, UK), while 2,4,6-tris (2-pyridyl)-S-triazine (TPTZ, 990 g·L⁻¹) and ferric chloride were acquired from Fluka (Buchs, Germany), and anhydrous sodium sulphate from Panreac (Barcelona, Spain). Ethanol absolute anhydrous was purchased from Carlo Erba (Marseille, France). Luteolinidin chloride was acquired from Chromadex (Los Angeles, CA, USA). Maltodextrin (DE 16.5–19.5) and Arabic gum was purchased from Sigma-Aldrich (Darmstadt, Germany). All other unlabelled chemicals and reagents were analytical, or HPLC-MS Optima grade from Fisher Scientific (Waltham, CA, USA).