Fluorescein sodium salt

Solvents used for the extraction and analysis were HPLC grade, namely ethanol, formic acid and acetonitrile, purchased from BDH Prolabo (Lutterworth, UK). Distilled water was of Milli-Q quality (Millipore Corp., Bedford, NY, USA). Anhydrous sodium carbonate (≥99.5%) and sodium phosphate (96%) were obtained from Kemika (Zagreb, Croatia), Folin-Ciocalteu reagent from Merck (Darmstadt, Germany), fluorescein sodium salt from Honeywell Riedel-de-Haën (Bucharest, Romania), Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid) from Acros Organics (Thermo Fisher Scientific, Geel, Belgium) and 2,2′-Azobis (2-amidinopropane) hydrochloride from Sigma-Aldrich (Steinheim, Germany).
Phenolic compounds of authentic standards of caffeic, gallic, ferulic, chlorogenic and p-coumaric acid, quercetin-3-glucoside, kaempferol-3-rutinoside and myricetin were purchased from Sigma–Aldrich (Steinheim, Germany); epicatechin, catechin, epigallocatechin gallate, epicatechin gallate, procyanidin B1, procyanidin B2, apigenin and luteolin from Extrasynthese (Genay, France); and quercetin-3-rutinoside from Acros Organics (Thermo Fisher Scientific, Geel, Belgium).

All of the chemicals and reagents used in this study were of analytical grade. Ethanol, acetone, sodium carbonate (Na₂CO₃), and potassium sulfate (K₂SO₄) were purchased from Gram-mol doo (Zagreb, Croatia); sodium tetraborate, L-cystein, sulfamic acid, gelatin, potassium hydroxide, chloroform, 1-phenyl-3-methyl-5-pyrazolone (PMP), and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox) from Acros Organics (Geel, Belgium); acetonitrile, trichloroacetic acid (TCA), silicone oil, and Folin–Ciocalteu reagent from Fisher Scientific (Leicestershire, UK); barium chlorid (BaCl₂) from abcr GmbH (Karlsruhe, Germany), fucoidan from Fucus vesiculosus, D-galacturonic acid, phenol, m-hydroxydiphenyl, 2,2-diphenyl-1-picrylhydrazyl (DPPH), arabinose, D-(+)-glucose, L-rhamnose, D-(−)-fructose, trimethylamine, 2,2′-Azobis(2-methylpropionamidine) dihydrochloride (AAPH), D-(+)-mannose, L-(−)-fucose, and ammonium acetate from Sigma-Aldrich (St. Louis, Missouri, USA); ethyl acetate, hexane, and absolute ethanol from Carlo Erba Reagents (Cornaredo, Italy); hydrochloric acid (HCl) from TKI Hrastnik (Hrastnik, Slovenia); sodium hydroxide from Lach-Ner (Zagreb, Croatia); sulfuric acid (H₂SO₄) from Scharlab S.L. (Barcelona, Spain); D-(−)-ribose from TCI (Portland, OR, USA); and fluorescein sodium salt from Honeywell Riedel-de-Haën (Bucharest, Romania).