Gentisic

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).

Analytical standards (all with purity ≥ 95%) of caffeic, 5-O-caffeoylqunic, gallic, ferulic, isoferulic, homoGentisic, protocatechuic, 3-hydroxybenzoic, 4-hydroxybenzoic, rosmarinic, 3,4-dihydroxyphenylacetic, vanillic, syringic, m-coumaric, o-coumaric, p-coumaric, salicylic, 3,4-dimethoxycinnamic, α-resorcylic, β-resorcylic, γ-resorcylic, 3,5-dimethoxybenzoic acid, 3-O-methylquercetin, chrysin, isorhamnetin, kaempferol, luteolin, morin, prunetin, rhamnetin, sakuranetin, taxifolin, and LC grade acetonitrile, methanol were purchased from Sigma-Aldrich Fine Chemicals (St. Louis, MO, USA). Gentisic, sinapic, veratric acids, eriodictyol, myricetin and rhamnazin were from ChromaDex (Irvine, USA). Apigenin and naringenin were from Roth (Karlsruhe, Germany) and quercetin was from Fluka (Buchs, Switzerland). LC grade water was prepared using a Millipore Direct-Q3 purification system (Bedford, MA, USA).