Carbomer 980

All standards, reagents, and solvents used were of analytical grade. Deionized water was produced using a Milli-Q water purification system (Milli-Q^®, Millipore, MA, USA). The standards used in the UPLC analysis (peonidin-3-galactoside, peonidin-3-arabinoside, cyaniding-3-galactoside, cyaniding-3-arabinoside, peonidin-3-glucoside, cyaniding-3-glucoside, cyanidin chloride, peonidin chloride, malvidin-3-galactoside, malvidin-3-arabinoside, and delphinidin-3-galactoside) were obtained from Extrasynthese (Genay, France). The chemicals applied in the modeling of gel formulations were sodium carboxymethyl cellulose, chitosan (deacetylation grade ≥ 75%, medium molecular weight), PEG400 sodium hydroxide (NaOH), and acetic acid, all obtained from Sigma-Aldrich Chemie GmbH (Steinheim, Germany). Carbomer 980 was purchased from Lubrizol (Wickliffe, OH, USA). Acetonitrile was purchased from Sigma-Aldrich (Steinheim, Germany), and formic acid was purchased from Merck (Darmstadt, Germany).

All solvents, reagents, and standards used were of analytical grade. The standards used in the HPLC analysis were the following: hyperoside, rutin, quercitrin, phloridzin, procyanidin B1, procyanidin B2 and chlorogenic acid, obtained from Extrasynthese (Genay, France); reynoutrin, (+)-catechin and (–)-epicatechin, purchased from Sigma-Aldrich GmbH (Buchs, Switzerland); and avicularin and isoquercitrin, obtained from Chromadex (Santa Ana, CA, USA). The chemicals applied in the modeling of semi-solid pharmaceutical forms were glycerin, castor oil, sorbitan monolaurate (Span 20), polyethylene glycol sorbitan monolaurate (Tween 20) and sodium hydroxide (NaOH), obtained from Sigma-Aldrich Chemie GmbH (Steinheim, Germany). Carbomer 980 was obtained from Lubrizol (Wickliffe, OH, USA). The reagents used in the antioxidant activity assay were 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and sodium acetate, acquired from Scharlau (Barcelona, Spain). Iron (III) chloride hexahydrate (FeCl₃ × 6H₂O) was purchased from Vaseline-Fabrik Rhenania (Bonn, Germany) and 2,4,6-tri(2-pyridyl)-s-triazine (TPTZ) was obtained from Carl Roth (Karlsruhe, Germany).