3 hydroxytyrosol

Sodium potassium l(+)-tartrate tetrahydrate was obtained from VWR Chemicals (Vienna, Austria). Potassium iodide was obtained from BDH Prolabo Chemicals (Leuven, Belgium). Iodine, sodium hydroxide (1 and 0.1 M), sodium thiosulfate (0.1 M) and sodium hydroxide pellets were obtained from Gram-mol (Zagreb, Croatia). Sulphuric acid (96%), starch (p.a., soluble) and phenolphthalein were obtained from Kemika (Zagreb, Croatia). Bromothymol blue was obtained from Merck (Darmstadt, Germany). (+)-Catechin, (-)-epicatechin, 2,5-dihydroxybenzoic acid (2,5-DHBA), 3,4-dihydroxybenzoic acid (3,4-DHBA), 3-hydroxytyrosol, caffeic acid, ellagic acid, quercetin, naringenin, luteolin-7-O-glucoside, pinobanksin, p-coumaric acid and syringic acid were obtained from Sigma-Aldrich, Merck (St. Louis, MO, USA). Gallic acid was obtained from Alfa Aesar (Thermo Fischer Scientific, Tewksbury, MA, USA). Ferulic acid and resveratrol were obtained from Extrasynthese (Genay, France). Honeywell research chemicals (Charlotte, NC, USA) supplied ethanol (HPLC grade) and acetonitrile (LC-MS grade). Sigma-Aldrich supplied formic acid (LC-MS grade), ultrapure water (LC-MS grade) and ethanol (96%).

Most of the standards used for the Ultra Pressure Liquid Chromatography (UPLC) analysis (caffeic, ferulic, p-coumaric, gallic, and chlorogenic acids; catechin; quercetin; 3-hydroxytyrosol, spiraeoside, oleureopin, dadzein, luteolin, naringenin, formononentin), as well as high pressure liquid chromatography (HPLC)-grade ethanol and acetonitrile were purchased from Sigma-Aldrich (Milano, Italy). Apigenin and hyperoside were purchased from Extrasynthese (Genay, France).

Standards of volatile and phenolic compounds were commercially obtained as follows: (Z)-3-hexen-1-ol (Toronto research chemicals Inc., Toronto, CA, USA); linalool, nonanal, phenylethyl alcohol, decanal, eugenol, 1,3,5-trimethoxybenzene, 3-hydroxytyrosol, caffeic acid, vanillin, trans-p-coumaric acid, trans-o-coumaric acid, apigenin-7-glucoside, oleuropein, pinoresinol, quercetin, luteolin, apigenin, diosmetin tyrosol, rutin, luteolin-7-glucoside, oleacein, and ligstroside from Sigma-Aldrich (St. Louis, MO, USA); verbascoside (HWI group, Rülzheim, Germany); and oleuroside (Phytolab, Vestenbergsgreuth, Germany). Alkane standard solutions C₈-C₂₀ and C₁₀, C₂₀-C_40, and derivatization reagent N,O-Bis(trimethylsilyl)trifluoroacet-amide (BSTFA) were purchased from Sigma-Aldrich (St. Louis, MO, USA); pentane, diethyl-ether, acetonitrile, and methanol were from VWR (Radnor, PA, USA); and anhydrous sodium sulfate was from Kemika (Zagreb, Croatia).

Standards of gallic acid (99%), 3-hydroxytyrosol (99.5%), (−)- gallocatechin (≥98%), caftaric acid (≥97%), (−)-epigallocatechin (≥95%), (+)-catechin (≥99%), (−)-epicatechin (≥95%), (−)- epigallocatechin gallate (≥95%), caffeic acid (99%), syringic acid (≥95%), coumaric acid (99%), ferulic acid (≥99%), piceatannol (99%), trans-resveratrol (≥99%), quercetin hydrate (95%), cinnamic acid (99%), quercetin 3-b-D-glucoside (≥90%), kaempferol-3-glucoside (≥99%) and malvidin-3-O- glucoside chloride (≥95%) were purchased from Sigma–Aldrich. The standard of 2-(4-hydroxyphenyl) ethanol (tyrosol) (≥99.5%) was obtained from Fluka (Buchs, Switzerland). Stock solutions of the above mentioned compounds were prepared in methanol at concentration levels of 1000 µgm l⁻¹. Calibration standards were dissolved in the initial mobile phase of each method (LMWP or anthocyanins, respectively). HPLC-grade Acetonitrile (MeCN) and formic acid (FA) were acquired from Mallinckrodt Baker (Inc. Phillipsburg, NJ, USA). Primary-secondary amine (PSA) and octa- decylsilane (C₁₈) were both obtained from Waters (Milford, MA, USA). Reagent grade NaCl, anhydrous Na₂CO₃, anhydrous MgSO₄ and anhydrous CaCl₂ were purchased from Sigma–Aldrich. Ultrapure water was obtained from a Milli-Q system (Millipore, Billerica, MA, USA).

All reagents, either analytical or HPLC grade, were purchased from Merck (Darmstadt, Germany). The phenol standards (3-hydroxytyrosol, 2-(4-hydroxyphenyl) ethanol (tyrosol), p-coumaric acid, vanillic acid, vanillin, luteolin, apigenin, pinoresinol, p-hydroxyphenylacetic acid (internal standard 1), o-coumaric acid (internal standard 2) oleuropein and caffeic acid), Trolox, fluorescein, and 2,2′-Azobis(2-amidinopropane) dihydrochloride (AAPH) were obtained from Sigma-Aldrich (St. Louis, MO, USA). Volatile standards 4-methyl-2-pentanol (internal standard), ethanol, ethyl propionate, 4-methyl-2 pentanone, butyl acetate, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-octanone, acetic acid, propionic acid, 1-octanol, butyric acid, heptanoic acid, nonanoic acid, (E)-2-hexenal, hexanal, hexanol, (E)-2-nonenal were purchased from Merck. Tocopherols standards were purchased from Calbiochem (Merck). All standards had a purity of 98% or higher.

Phorbol 12-myristate 13-acetate (PMA), water soluble unesterified cholesterol, apolipoprotein (apo) A1, resazurin sodium salt, cycloheximide, and digitonin were purchased from Sigma-Aldrich (Vienna, Austria). Pioglitazone was obtained from Molekula (Munich, Germany). [³H]-cholesterol (1 mCi, 37 MBq) was provided by Perkin Elmer Life Sciences (Vienna, Austria). The olive oil-derived compounds (uvaol, erythrodiol, maslinic acid, oleanolic acid, betulinic acid, oleuropein, 3-hydroxytyrosol, and chlorogenic acid) were supplied by Sigma-Aldrich (Vienna, Austria). Oleocanthal (>80% purity) was isolated from olive oil as recently described (Adhami et al., 2015 (link)) and was and kindly provided by Prof. Liselotte Krenn (University of Vienna). Bovine serum albumin (BSA-fatty acid free) was from Roth (Karlsruhe, Germany). All tested compounds were dissolved in DMSO, aliquoted and stored at −20°C until use. An equal amount of DMSO was always tested in each condition in all experiments to assure that the solvent vehicle does not influence the results.

US Pharmacopeia reference standard compounds, including trans-RSV, (+)-catechin, (–)-epicatechin, gallic acid, 3-hydroxytyrosol, isochlorogenic acid, 3, 4-dihydroxyphenylacetic acid, 4-methyl gallic acid, 3, 4-dihydroxyphenylacetic acid, 3-hydroxybenzoic acid, caffeic acid, 4-hydroxybenzoic acid, vanillic acid, dihydromyricetin, syringic acid, resveratrol-3-glucoside, dihydroferulic acid, sinapic acid, taxifolin, ferulic acid, 3-hydrocinnamic acid, phenylacetic acid, and trans-2-hydrocinnamic acid, were purchased from Sigma Chemical Co. (St. Louis, MO, USA). Primary analytical standard (Grade P) compounds, including procyanidin B2, procyanidin C1, quercetin, and cyanidin-3-glucoside, were purchased from ChromaDex (Irvine, CA, USA). The HPLC grade water, acetonitrile (ACN), methanol (MeOH), formic acid (FA), and trifluoroacetic acid (TFA) were obtained from Fisher Scientific Co. (Fair Lawn, NJ, USA).