Protocatechuic

Acetonitrile (hypergrade for LC-MS), formic acid (for LC-MS) and methanol (analytical grade) were purchased from Merck, Sofia, Bulgaria. The authentic standards used for compound identification were obtained from Extrasynthese (Genay, France) for protocatechuic, p-hydroxyphenylacetic, vanillic, gentisic, ferulic, p-coumaric, o-coumaric acid, rutin, hyperoside, luteolin 7-O-rutinoside, luteolin 7-O-glucoside, isoquercitrin, kaempferol 3-O-rutinoside, isorhamnetin 3-O-rutinoside, kaempferol 3-O-glucoside, isorhamnetin 3-O-glucoside, apigenin 7-O-glucoside, quercetin, apigenin, luteolin, chrysoeriolq eupatilin and genkwanin. Caffeic, 3,4-dicaffeoylquinic, 3,5-dicaffeoylquinic 1,5-dicaffeoylquinic, 4,5-dicaffeoylquinic and 3,4,5- tricaffeoylquinic acids were supplied by Phytolab (Vestenbergsgreuth, Germany). Chlorogenic acid and isorhamnetin were purchased from Sigma-Aldrich (St. Louis, MO, USA). Diclofenac, silymarin, collagenase, 1-chloro-2,4-dinitrobenzene, beta-nicotinamide adenine dinucleotide 2′-phosphate reduced tetrasodium salt (NADPH), ethylenediaminetetraacetic acid (EDTA), bovine serum albumin (fraction V) and 2,2′-dinitro-5,5′dithiodibenzoic acid (DTNB) were obtained from Merck (Darmstadt, Germany). Reduced glutathione (GSH), oxidized glutathione (GSSG), glutathionereductase (GR) and cumene hydroperoxide were purchased from Sigma Chemical Co. (Taufkirchen, Germany).

Acetonitrile (hypergrade for LC–MS), formic acid (for LC-MS), and methanol (analytical grade) were purchased from Chromasolv (Bulgaria). The authentic standards gallic, vanillic, protocatechuic, gentisic, salicylic, p-coumaric, rutin, isoquercitrin, luteolin 7-O-rutinoside, luteolin 7-O-glucoside, isorhamnetin 3-O-glucoside, apigenin 7-O-glucoside, luteolin, quercetin, apigenin, and chrysoeriol were obtained from Extrasynthese (Genay, France). Rosmarinic, caffeic, ferulic, chlorogenic, neochlorogenic, 3,4-dicaffeoylquinic, 3,5-dicaffeoylquinic, 1,5-dicaffeoylquinic, and 4,5-dicaffeoylquinic acid were supplied from Phytolab (Vestenbergsgreuth, Germany). Sonchuside A and 8-acetyl-15β-D -glucopyranosyllactucin were previously isolated and identified by Zidorn et al., 2005 [8 (link)].

Acetonitrile, formic acid (for LC–MS) and methanol (analytical grade) were provided from Merck (Merck, Sofia, Bulgaria). The reference standards, using for UHPLC-HRMS protocatechuic, p-coumaric, m-coumaric, o-coumaric, vanillic, gentisic and salicylic acids, luteolin 7-O-glucoside, kaempferol-3-O-rutinoside, kaempferol 3-O-glucoside, isorhamnetin 3-O-glucoside, nepetin 7-O-glucoside, hyperoside, apigenin, quercetin, kaempferol, hispidulin, chrysoeriol, isorhamnetin, jseocidine, and luteolin were obtained from Extrasynthese (Genay, France). Chlorogenic, neochlorogenic, caffeic, 3,4-dicaffeoylquinic, 3,5-dicaffeylquinic and 1,5-dicaffeoylquinic acids, as well as dehydrocostus lactone, isoalantolactone, alantolactone, and partenolide, were supplied from Phytolab (Vesten-Bergsgreuth, Germany).