Salicylic

Pepsin from porcine stomach mucosa (250 U/mg), pancreatin (8 × USP) from porcine pancreas, porcine bile extract, mucin from porcine stomach-type II, albumin, resazurin, cysteine, peptone, yeast extract, pectin, xylan, gum arabic, potato starch, casein, glucose, and inulin were purchased from Sigma-Aldrich Chemical Co. (St. Louis, MO, USA). Phenolic compounds standards (2,4 dihydroxybenzoic, 3,4 dihydroxybenzoic, gallic, benzoic, caffeic, ferulic, p-coumaric, salicylic, rosmarinic, and 5-caffeoylquinic acids) were purchased from Sigma-Aldrich Chemical Co. All solvents were HPLC grade from Tedia (Fairfield, OH, USA). HPLC grade water (Milli-Q system, Millipore, Bedford, MA, USA) was used throughout the experiments.

Ethanol and sodium carbonate were purchased from Avantor Performance Materials Poland (Gliwice, Poland). Gallic, m-coumaric, o-coumaric, p-coumaric, caffeic, 5-O-caffeoylqunic, ferulic, isoferulic, vanillic, salicylic, 3-hydroxybenzoic, 4-hydroxybenzoic, protocatechuic, syringic, rosmarinic acid, quercitrin, apigenin 7-O-glucoside, eriocitrin, taxifolin, 3-O-methylquercetin, isorhamnetin, isorhamnetin-3-O-glucoside, luteolin, kaempferol, rutin, hyperoside, isoquercetin, sakuranetin, aluminum chloride, and LC–MS grade acetonitrile were purchased from Sigma-Aldrich Chemical Co. (St. Louis, Mo, USA). Folin–Ciocalteu reagent was supplied by Chempur (Piekary Śląskie, Poland). Quercetin was purchased from Fluka (Buchs, Switzerland). Catechin, naringenin 7-O-glucoside, eriodictyol, luteolin-7-O-glucoside, naringenin 7-O-glucoside, luteolin 3,7-diglucoside, nicotiflorin, narcissoside, gentisic, sinapic acid, and myricetin were provided by ChromaDex (Irvine, CA, USA). Astragalin, apigenin, naringenin, kaempferol-3-rutinoside, and tiliroside were supplied by Roth (Karlsruhe, Germany). LC–MS grade water was prepared using a Millipore Direct-Q3 purification system (Bedford, MA, USA).

Standards of caffeic, gallic, ferulic, isoferulic, protocatechuic, 4-OH-benzoic, vanillic, p-coumaric, salicylic, and LC grade acetonitrile were purchased from Sigma–Aldrich Fine Chemicals (St. Louis, MO, USA). Gentisic and sinapic acids were from ChromaDex (Irvine, CA, USA). The LC grade water was prepared using a Millipore Direct-Q3 purification system (Bedford, MA, USA). Ethanol and methanol (reagent grade purity), used for the preparation of extracts, Folin-Ciocalteu reagents, and all analytical grade reagents were obtained from Avantor Performance Materials (Center Valley, PA, USA).