Kuromanin

Reagents were purchased from various suppliers as follows: Authentic standards of kuromanin (cyanidin 3-O-glucoside chloride), chlorogenic acid (3-caffeoylquinic acid), gentisic acid, rutin (quercetin 3-O-rutinoside) (Extrasynthèse, Genay, France); the standard for carotenoids (lutein, carotene, α-carotene, β-carotene and lycopene) were purchased from CaroteNature (Lupsingen, Switzerland); gallic acid, Folin-Ciocalteu's phenol reagent, Trolox [(S)-(-)-6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid], ABTS [2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)], fluorescein disodium, AAPH [2,2′-azobis (2-methyl-propionamide)], ascorbic acid, meta-phosphoric acid, DTT (dithiothreitol), BHT (butylated hydroxytoluene) as well as acetonitrile, ethanol, methanol, acetone, methyl tert-butyl ether, formic acid and acetic acid (all HPLC grade) (Sigma-Aldrich, St. Louis, MO, USA). In all experiments Milli-Q (Merck Millipore, Darmstadt, Germany) water was used.

Sodium alginate (SA) (CAS: 9005-38-3), calcium chloride (CaCl₂) (CAS: 10043-52-4), 37% v/v hydrochloric acid solution (CAS: 7647-01-0) and NaOH in pellet form (CAS: 1310-73-2) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Sodium chloride (CAS: 7647-14-5) was purchased from Carlo Erba Reagents (Cornaredo, Italy). Authentic standards of kuromanin (cyanidin 3-O-glucoside chloride), oenin, quercetin, rutin (quercetin 3-O-rutinoside) kaempferol, catechin and epicatechin were purchased from Extrasynthèse, Genay, France. Gallic acid, coutaric acid, caftaric acid, Folin–Ciocalteu phenol reagent, Trolox [(S)-(-)-6-hydroxy-2,5,7,8 tetramethylchroman-2-carboxylic acid], ABTS [2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)], acetonitrile, ethanol, formic acid and organic acids (all HPLC grade) were purchased from Sigma-Aldrich, St. Louis, MO, USA. In all experiments, Milli-Q (Merck Millipore, Darmstadt, Germany) water was used. Soy extract (SE) was obtained from soy seeds purchased from a local supermarket.