Astilbin

Acetonitrile and ethanol were purchased from Thermo Fisher Scientific (Courtaboeuf, France). A Millipore Milli-Q system (Merck Millipore, Molsheim, Germany) provided ultrapure water. Gallic acid, caffeic acid, E-Resveratrol, E-piceatannol, catechin, epicatechin, gallocatechin, E-piceid, astilbin, quercetin-3-O-glucuronide, procyanidin B1 and procyanidin B2 were obtained from Sigma-Aldrich (St. Louis, MO, USA); E-ε-viniferin and quercetin-3-O-glucoside were purchased from Extrasynthèse (Genay, France) and E-miyabenol C from Ambinter (Paris, France). Pallidol and E-δ-viniferin were graciously provided by Mary-Lorène Goddard (EA-3991, Université de Haute-Alsace, Colmar, France). Z/E-vitisin B, ampelopsin A and hopeaphenol were purified from grape canes as previously described [37 (link)]. The 2,2′-Azo-bis-(2-amidinopropane) hydrochloride (ABAP), fluorescein, 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS), potassium persulfate, 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,4,6-Tri(2-pyridyl)-s-triazine (TPTZ), Iron(III) chloride (FeCl₃), copper(II) chloride (CuCl₂), 2,9-Dimethyl-1,10-phenanthroline (neocuproine) and 3-(2-Pyridyl)-5,6-diphenyl-1,2,4-triazine-p,p′-disulfonic acid monosodium salt hydrate (ferrozine) were obtained from (Sigma-Aldrich, Saint-Quentin Fallavier, France).

The S. mutans strain (ATCC 25175) used throughout this study was purchased from the American Type Culture Collection (ATCC, Manassas, VA, USA). Bacteria were anaerobically cultured in a BHI broth (Sigma) at 37 °C with shaking. Astilbin was purchased from the Chengdu Herbpurify Corporation (Chengdu, China) with a purity > 98%. Astilbin was dissolved in dimethyl sulfoxide (DMSO) (Sigma-Aldrich, St. Louis, MO, USA) to 102.4 mg/mL as a colorless, transparent solution, and stored at 4 °C until needed. The substrate peptide Abz-LPATG-Dap(Dnp)-NH₂ (Abz: ortho-aminobenzoic acid; Dnp: 2,4-dinitrophenyl) was synthesized by GL Biochem (Shanghai, China).

Methanol, ethanol, acetonitrile, formic acid, aluminium chloride (AlCl₃), sodium nitrite (NaNO₂), sodium hydroxide (NaOH), and Advanced glycation end products (AGEs) were purchased from Merck Co. (Darmstadt, Germany). Dimethyl sulfoxide (DMSO), streptomycin, phosphate buffer saline, 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), catechin, hyperoside, quercitrin, quercetin, and astilbin and were purchased from Sigma Co. (St. Louis, MO, USA). Fetal bovine serum (FBS) and Dulbecco’s Modified Eagle’s Medium (DMEM) were purchased from Gibco (Invitrogen, Carlsbad, CA, USA).

The standards of gallic, protocatechuic, caffeic, syringic, p-coumaric, ferulic, ellagic and caftaric acids, tyrosol, thyptophol, quercetin, myricetin, astilbin, (+)-catechin and (−)-epicatechin, dextrans, and pectins were purchased from Sigma-Aldrich Chemical Co. (St. Louis, MO, USA). Polyethylene membranes of 0.45 μm and 0.22 μm pore size were acquired from EMD Millipore (Billerica, MA, USA). Sodium sulphate (anhydrous), potassium metabisulfite, vanillin (99%), ethyl acetate, diethyl ether, sodium hydroxide, acetic acid, formic acid, sulphuric acid, ethanol, hydrochloric acid and high-performance liquid chromatography (HPLC)-grade acetonitrile, methanol, and ammonium formate were purchased from Merck (Darmstadt, Germany). All the reagents were of analytical grade or higher.

Gallic acid (1), caffeic acid (2), E-resveratrol (3), E-piceatannol (4), catechin (5), epicatechin (6), gallocatechin (7), E-piceid (8), astilbin (10), quercetin-3-O-glucoside (16), and quercetin-3-O-glucuronide (23) were purchased from Sigma-Aldrich standards (St. Louis, MI, USA). Procyanidins B1 (24), B2 (25), and B3 (27) were purchased from Extrasynthèse (Genay, France). E-ε-viniferin (13), E-δ-viniferin (15), ampelopsin A (17), E-miyabenol C (32), hopeaphenol (36), isohopeaphenol (37), and Z/E-vitisin B (41) were obtained as previously described [2 (link)]. Acetonitrile, methanol, and formic acid were purchased from ThermoFisher Scientific (Courtaboeuf, France). Ultra-pure water was prepared with a Milli-Q water purification system (Merck Millipore, Molsheim, France).