Vanillic acid

The analytical standards of hydroxytyrosol, tyrosol, vanillic acid, oleuropein, luteolin, and apigenin were purchased from Extrasynthese (Genay, France). p-Coumaric acid, ferulic acid, pinoresinol, syringic acid, α-tocopherol, 2,2’-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS), and Trolox were purchased from Sigma-Aldrich (Milan, Italy). High performance liquid chromatography (HPLC) -grade methanol, hexane, and isopropanol (IPA) were purchased from Sigma-Aldrich (Milan, Italy). Water (resistivity above 18 MΩ cm) was obtained from a Milli-Q SP Reagent Water System (Millipore, Bedford, MA, USA). Solvents and solutions were filtered through a 0.45-µm polytetrafluoroethylene (PTFE) filter from Supelco (Bellefonte, PA, USA).

All solvents used (methanol, acetonitrile, acetic acid, water and ethyl acetate) were HPLC-grade and were purchased from Merck (Darmstadt, Germany). Protocatechuic acid, 4-hydroxybenzoic acid, vanillic acid, chlorogenic acid, trans-p-coumaric acid, eriodictyol-7-O-glucoside, eriodictyol, naringenin, naringenin-7-O-glucoside, kaempferol-3-O-rutinoside, kaempferol-3-O-glucoside, isorhamnetin-3-O-glucoside, quercetin, kaempferol, isorhamnetin, quercetin-3-O-rutinoside, quercetin-3-O-galactoside, quercetin-3-O-glucoside, isorhamnetin-3-O-rutinoside, catechin and epicatechin were purchased from Extrasynthese (Genay, France). Other chemicals were of analytical grade.

Ammonium acetate, acetone, and 2-propanol and formic acid werepurchased from Carlo Erba (Milan, Italy). Standard solutions of vanillic acid, syringic acid and chlorogenic acid were purchased from Extrasynthese (Genay Cedex, France). Acetonitrile and methanol were purchased from Merck (Darmstadt, Germany). The solid-phase extraction SPE cartridges used were Waters Oasis Hydrophilic-Lipophilic Balance (HLB) (200 mg) and ultrapure deionized water, with resistivity of 18.2 MΩ cm, obtained from the Milli-Q^® Integral water purification system with Q-pod (Millipore, Bedford, MA, USA). All solutions were filtered through 0.45 membranes (Millipore, Bedford, MA, USA) and degassed before use. Ferulic acid, gallic acid, kaempferol, quercetin, and rutin, N,O-bis(trimethylsilyl)trifluoroacetamide plus 1% of trimethylchlorosilane, Di(2-ethylhexyl)phthalate, Dulbecco’s modified eagles Medium (DMEM) high glucose, 2′,7′-dichlorodihydrofluoresceine diacetate (DCFH2-DA), 3-4,5-dimethylthiazol-2-yl,2,5-diphenyltetrazolium bromide (MTT), phosphate buffer saline (PBS), fetal bovine serum (FBS), streptomycin and penicillin mixture, and trypsin-Ethylenediaminetetraacetic acid (EDTA) were acquired from Sigma-Aldrich S.r.l. (Milan, Italy).

All chemicals and reagents were either analytical-reagent or HPLC grade. Ultrapure deionized water, with a resistivity of 18.2 MΩ cm, was obtained from a Milli-Q^® Integral water purification system with a Q-pod purchased from Millipore (Bedford, MA, USA). Acetic acid, acetonitrile, and 2-propanol were purchased from VWR International S.r.l. (Milan, Italy); hydrochloric acid and sodium hydroxide were purchased from Carlo Erba (Milan, Italy). The methanol HPLC gradient grade was obtained from Merck (Darmstadt, Germany). Standard solutions of vanillic acid, trans-ferulic acid, syringic acid, myricetin, naringenin, pinocembrin, luteolin, and hesperidin were purchased from Extrasynthese (Genay Cedex, France). Chlorogenic acid was purchased from HWI Analytik GmbH (Rülzheim, Germany). Gallic acid, caffeic acid, apigenin, quercetin, kaempferol, catechin, epicatechin, indometacine, histamine, and anti-α-tubulin antibody were purchased from Sigma-Aldrich S.r.l. (Milan, Italy). The IFN-γ was obtained from Pepro Tech EC (London, England). The anti-ICAM-1 antibody (sc-51632) was purchased from Santa Cruz Biotechnology (Milan, Italy), anti-COX-2 (35-8200) from Thermo Fisher Scientific (Milan, Italy), and -α- tubulin (T6074) from Sigma-Aldrich (Milan, Italy).

Fast Blue BB (FBBB) [4-benzoylamino-2,5-dimethoxybenzenediazonium chloride hemi-(zinc chloride) (Rebello et al., 2016 (link)), bile extract porcine, pancreatin from porcine pancreas, pepsin from porcine gastric mucosa, α-amylase from human saliva, 2,2′-azinobis 3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 2,2′-diazobis-(2-aminodinopropane)-dihydrochloride (AAPH), fluorescein, 2,2-diphenyl-1-picrylhydrazyl (DPPH) were purchased from Sigma-Aldrich, Co. (St. Louis, MO, United States). Standards of chlorogenic acid, 2-coumaric acid, 2,4-dihydroxybenzoic acid, 4-hydroxybenzoic acid, vanillic acid, and vanillin were provided by Extrasynthese (Lyon, Genay Cedex, France). Standards of 6-hydroxy-2,5,7, 8-tetramethyl-2-carboxylic acid (Trolox), gallic acid, caffeic acid, ferulic acid, vitexin, D-(+)-glucose, D-(+)-galactose, D-(+)-xylose, D-(–)-arabinose, and stachyose were acquired from Sigma-Aldrich, Co. (St. Louis, MO, United States). Standards of 3³-α-L-plus 2³-α-L-arabinofuranosyl-xylotetraose (XA³XX/XA²XX), 2³,3³-di-α-L-arabinofuranosyl-xylotriose (A^{2, 3}XX), and xylotriose were obtained from Megazyme (Wicklow, Ireland). Raffinose and cellobiose standards were supplied by Merck (Darmstadt, Germany).

Acetonitrile HPLC quality was supplied by Labscan (Dublin, Ireland), and formic acid HPLC quality was from Acros Organic (Geel, Belgium). Protocatechuic acid, vanillic acid, syringic acid, caffeic acid, 3-coumaric acid, ethyl gallate, 3,4′,5 trihydroxystilbene-3-O-d-glucoside (trans-piceid), (+)-catechin, (−)-epicatechin, epicatechin gallate, procyanidin B₁, procyanidin B₂, quercetin-3-O-galactoside (hyperoside), quercetin-3-O-rutinoside (rutin), quercetin-3-O-glucuronide, quercetin-3-O-glucoside, and quercetin dehydrate were purchased from Extrasynthèse (Genay, France). Glucose, xylose, phenol, gallic acid, 4-hydroxybenzoic acid, trans-caftaric acid, ellagic acid, protocatechuic aldehyde, trans-resveratrol, 6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid (Trolox), potassium persulfate, 2,2´ azinobis(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS), 2,2 diphenyl-1-picrylhydrazyl (DPPH), and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) were obtained from Sigma-Aldrich (Madrid, Spain). Disodium carbonate, Folin-Ciocalteau reagent, methanol, and ethanol were purchased from Panreac (Barcelona, Spain).

Analytical standards of 3,4-dihydroxybenzoic acid (>98.2%), acacetin (>98.7%), apigenin (>99%), caffeic acid (>98.5%), catechin (>99%), chlorogenic acid (>99%), chrysin (>99%), daidzein (>99%), galangin (>98.5%), gallic acid (>95.5%), genistein (>99%), (-)-epicatechin (>90.3%), folic acid (>91.2%), formononetin (>99%), isovitexin (>99%), luteolin (>99.9%), myricetin (>98%), o-coumaric acid (>99.7%), p-coumaric acid (>99.6%), p-hydroxybenzoic acid (>99.9%), pantothenic acid (>98.6%), phenylacetic acid (>99.7%), rhamnetin (>99%), rutin trihydrate (>94%), quercetin (>98%), sinapic acid (>96%), syringic acid (>98.5%), trans-ferulic acid (>99.8%), vanillic acid (>98.2%) were purchased from Extrasynthese (Lyon, France) or Sigma-Aldrich (St. Louis, MO, USA). The standard of (-)-cis, trans-abscisic acid (>99.9%) was purchased from Santa Cruz Biotechnology (Dallas, TX, USA), and kaempferol (>97%) was purchased from ChromaDex (Santa Ana, CA, USA). HPLC-MS grade acetonitrile (MeCN) and dimethyl sulfoxide (DMSO) were purchased from Merck (Darmstadt, Germany), while formic acid (FA), hydrochloric acid (HCl), and sodium chloride (NaCl) were purchased from Sigma-Aldrich.