6 hydroxy 2 5 7 8 tetramethyl 2 carboxylic acid

Saline peptone water, Brain Heart Infusion (BHI), Tryptic Soy Broth (TSB) supplemented with Yeast, Plate Count Agar (PCA), Tryptone Sulphite Neomycin (TSN), Dextrose Sabouraud (DS), and Mannitol Egg Yolk Polymyxin (MYP) mediums were obtained from Merck KGaA, (Darmstadt, Germany). Acetonitrile; amphotericin B solution (250 μg/mL); 2,2′-Azinobis 3-ethylbenzothiazoline-6-sulphonic acid (ABTS); Fetal Bovine Serum (FBS); glacial acetic acid; hydrochloric acid; 6-hydroxy 2,5,7,8-tetramethyl-2-carboxylic acid (Trolox); L-glutamine solution (200 mM); MEM (Minimum Essential Medium); methanol; penicillin (10,000 U/mL); pure phenolic compounds (caffeic acid, catechin, epicatechin, epicatechin gallate, ethyl gallate, gallic acid, gentisic acid, p-coumaric acid, procyanidin B1, procyanidin B2, protocatechuic acid, syringic acid, t-resveratrol, t-piceid, and vallinic acid); streptomycin solution (P/S; 100 mg/mL); and 2,4,6-Tris (2-pyridyl)-S-triazine (TPTZ) were purchased from Sigma-Aldrich Chemical Co. (St. Louis, MO, USA). Folin–Ciocalteu (FC) reagent, 70% (v/v), iron (III)-chloride acid (FeCl3), iron (II)-sulphate (FeSO₄), sodium acetate (NaC₂H₃O₂), and sodium carbonate (Na₂CO₃) were purchased from Panreac Quimica S.L.U. (Barcelona, Spain). Malvidin-3-glucoside was obtained from Estrasynthese (Genay, France).

Sodium carbonate anhydrous (Na₂CO₃), Folin-Ciocalteu reagent, sodium nitrite solution (NaNO₂), aluminum chloride hexahydrate solution (AlCl₃, 6 H₂O), vanillin, catechin and gallic acid were purchased from Fluka (Buchs, Switzerland). Sulfuric acid (H₂SO4) was obtained from Merck (Darmstadt, Germany). Fluorescein sodium salt (FL), 20,70 dichlorofluorescin-diacetate (DCFH-DA), 20,70-dichlorofluorescin (DCFH), 20,70-dichlorofluorescein (DCF), 6-hydroxy-2,5,7,8-tetramethyl-2-carboxylic acid, tert-butyl hydroperoxide (t-BuOOH), (Trolox), quercetin, and 2,20-azobis(2-amidino-propane) dihydrochloride (AAPH) were all purchased from Sigma-Aldrich (Oakville, ON). All the solvents were purchased from EMD (Canada).

Rojo Duro onion samples were provided by the farm “Azienda Agraria Turrioni Fiorella” (Cannara-Perugia, Italy). The extract from OL was prepared about five months after the onion harvesting.
Folin–Ciocalteu reagent, 2,4,6-tris(2-pyridyl)-s-triazine (TPTZ), 6-hydroxy-2,5,7,8-tetramethyl-2-carboxylic acid (Trolox), 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydrochloric acid (HCl), ferric chloride (FeCl₃), sodium acetate (NaOAc), sodium carbonate (Na₂CO₃), acetic acid (AcOH), gallic acid (GA) and ethanol (EtOH) and bentonite nanoclay were purchased from Sigma-Aldrich (Milano, Italy). Polyvinylpyrrolidone K90 (PVP K90) was furnished by ISP (Baar, Switzerland). Sodium carboxymethylcellulose (NaCMC) was purchased from Caelo (Hilden, Germany). Ultrapure water was obtained from a reverse osmosis based Milli Q System (Millipore, Milano, Italy). Other reagent grade chemicals and solvents were used without further purification. Ultrapure water was sterilized in a steam autoclave (121 °C, 2118 millibar absolute pressure and relative pressure 1360 millibar).
The simulated wound fluid (SWF) pH 6.5 was prepared by dissolving 8.30 g of NaCl and 0.28 g of CaCl₂ in 1000 mL of ultrapure water [36 (link)].