Thiobarbituric acid

Tocopherol standards and malondialdehyde were purchased from Merck Ltd. (Darmstadt, Germany). Ammonium iron (II) sulfate, thiobarbituric acid, trichloroacetic acid, hydrochloric acid (37%), and glacial acetic acid were purchased from Panreac (Barcelona, Spain). Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid) was purchased from Glentham Life Sciences (Corsham, UK). Dichloromethane and isooctane were obtained from Carlo Erba (Vaul de Reuil, France). Ammonium thiocyanate and chloroform were purchased from Penta (Prague, Czech Republic). Cyclohexane and p-anisidine were obtained from Sigma-Aldrich (St. Louis, Burlington, MA, USA). Ethanol (99.8%) was bought from Fischer Scientific (Loughborough, UK). Hydrogen peroxide (35%) was obtained from Chemco (Malsch, Germany).

All chemicals were analytical grade. Methanol (MeOH), iron (II)-sulfate-7-hydrate and trichloroacetic acid were obtained from Riedel-de Haën™ (Seelze, Germany) and formic acid, water and acetonitrile (ACN) from Fisher Scientific, OptimaTM (Hampton, NH, USA). Trifluoroacetic acid (TFA), potassium dihydrogen phosphate, tris(hydroxymethyl)aminomethane (Tris) and sodium chloride were bought from Merck (Darmstadt, Germany). Ethanol 96% was bought from Carlo Erba (Peypin, France), gentiopicroside from TransMIT (Hesse, Germany) and potassium chloride from Fluka (Seelze, Germany). Acetylcholinesterase (AChE), acetylcholine iodide (AChI), 5-5′-dithiobis (2-nitrobenzoic acid) (DTNB), HMG-CoA Reductase assay kit, gallic acid, 2,2-diphenyl-1-picrylhydrazyl (DPPH), butylated hydroxytoluene (BHT), quercetin, rutin and galantamine were obtained from Sigma (Barcelona, Spain). Magnesium chloride hexahydrate, thiobarbituric acid, hydrogen peroxide, sodium hydrogen phosphate and 1-butanol were bought to PanReac (Barcelona, Spain). Sodium hydroxide was obtained from JT Baker, UK and sodium nitroprusside and Griess reagent from VWR Chemicals PL.

Quercetin (purity ≥ 95%, Bangalore, Karnataka, India) and iron (III) chloride hexahydrate (purity ≥ 99%, Taufkirchen, Germany) were purchased from Sigma-Aldrich (Saint Louis, MO, USA). Dipotassium hydrogen phosphate anhydrous (purity ≥ 98%), potassium dihydrogen phosphate (purity ≥ 98%), sodium acetate anhydrous (purity ≥ 99%), hydrochloric acid (HCl, 37%), thiobarbituric acid (purity ≥ 98%), 1-butanol (purity ≥ 99.5%), and formic acid (FA, purity ≥ 98%) were purchased from PanReac AppliChem (Darmstadt, Germany). Furthermore, 2,4,4-tris(2-pyridyl)-1,3,5-triazine (TPTZ, purity ≥ 96%) was purchased from BLDpharm (Shanghai, China). Acetic acid (purity ≥ 99.8%) and ortho-phosphoric acid (purity ≥ 85%) were purchased from Component-Reaktiv (Moscow, Russia). Sodium thiosulfate standard titer was purchased from LLC Himtitry (Pereslavl-Zalessky, Russia). Starch indicator and sodium sulphate anhydrous were purchased from Himmed (Moscow, Russia). Acetic acid was purchased from Labtech (Moscow, Russia), and potassium iodide was purchased from Reahim (Moscow, Russia). Deionized water for chromatography (18 W) was obtained using a Milli-Q Merck water purification system (Millipore, Darmstadt, Germany).