2.1. Reagents

Choline chloride (98%), lactic acid (85%), catechin hydrate (≥98%), epicatechin (≥98%), caffeine (≥98%), theobromine (≥98%), 2,2-diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl (DPPH), (±)-6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid (Trolox), sodium acetate (≥99%), glacial acetic acid, 2,4,6-tri(2-pyridyl)-s-triazine (TPTZ), and iron(III) chloride hexahydrate, ethylene glycol, absolute alcohol (≥99.5%), and gallic acid (99.9%) were purchased Merck KGaA (Darmstadt, Germany). Glycerol (99.5%), anhydrous sodium carbonate (99.5%), and methanol (99.8%) were purchased from Loba Chemie Pvt. Ltd. (Mumbai, India), and Folin-Ciocalteu reagent from Winkler (Santiago, Chile).