Malondialdehyde

Antibodies were purchased from Santa Cruz Biotechnology Inc. (Dallas, TX, United States). Sucrose was purchased from Vetec Quimica Fina Ltda. (Rio de Janeiro, Brazil). Streptozotocin, sodium citrate, citric acid, Tris, EDTA, albumin, potassium cyanide, NADH, ubiquinone, rotenone, succinate, 2,6-dichlorophenolindofenol, decylubiquinone, ubiquinol, cytochrome c, antimycin A, adrenaline, glycine, hydrogen peroxide, malondialdehyde, butanol, and tween-20 were obtained from Sigma (St. Louis, MO, United States). All the chemicals were of analytical grade.

(-)-Epicatechin (EC), 2´-7´dichlorofluorescein diacetate (DCFH-DA), ampicillin sodium salt, nistatine, agar, yeast extract, fluorodeoxyuridine (FUdR), phosphate-buffered saline (PBS), cholesterol, Bradford reagent, guanidine hydrochloride (GuHCl), 2,4-dinitrophenylhydrazine (DNPH), malondialdehyde, hexanal, hexenal and 4-HNE were purchased from Sigma-Aldrich (Madrid, Spain). Dimethyl sulfoxide (DMSO) was obtained from Panreac (Barcelona, Spain) and trichloroAcetic acid from Fluka Analytical (Madrid, Spain). HPLC grade acetonitrile was from Carlo Erba (Rodano, Italy). Acetic acid was from Merck (Darmstadt, Germany). Fluorescein thiosemicarbazide was from Carbosynth (Berkshire. UK)

Tween 80, Butylated hydroxytoluene (BHT), Folin–Ciocalteu reagent, 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH), and malondialdehyde (MDA) were obtained from Sigma‐Aldrich Chemie. Analytical grade acetone, ethanol, methanol, chloroform, butanol, hexane–isopropanol, ammonium thiocyanate, iron chloride (II) and (III), potassium hydroxide (KOH), phenolphthalein, disodium hydrogen phosphate (Na₂HPO₄), sodium dihydrogen phosphate (NaH₂PO₄), thiobarbituric acid (TBA), and 1,1,3,3‐tetraethoxypropane (TEP) were procured from Merck Company.

Reduced glutathione (GSH), 5,50-dithiobis-(2-nitrobenzoic acid) (DTNB), riboflavin, l-methionine, nitroblue tetrazolium chloride (NBT), bovine serum albumin (BSA), Coomassie brilliant blue G-250 dye, malondialdehyde (MDA), 2-thiobarbituric acid (TBA), formic acid, HPLC grade acetonitrile (ACN), HPLC grade methanol, lipopolysaccharide (LPS) from E. coli, l-nitro-arginine (LNA), and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) were acquired from Sigma Aldrich Co. (St. Louis, MO, USA). Hydrogen peroxide (H₂O₂) and trichloroacetic acid (TCA) were purchased from Thermo Fisher Scientific Co. (San Jose, CA, USA). Reagents and media for cell line included trypan blue dye, trypsin-EDTA, fetal bovine serum (FBS), penicillin, streptomycin, and Roswell Park Memorial Institute (RPMI) 1640 medium were purchased from Gibco BRL, Life Technologies Inc. (Rockville, MD, USA) and Griess reagent was from Merck (Darmstadt, Germany).

Following incubation of erythrocytes with SiNPs or normal saline (control), the mixture was centrifuged, and the resulting supernatants were subjected to oxidative damage/stress marker assays including LPO, CAT, SOD, and GSH. NADPH-dependent erythrocyte membrane LPO was measured as a thiobarbituric acid reactive substance using malondialdehyde as standard (Sigma-Aldrich Fine Chemicals, St. Louis, MO, USA. GSH concentration (Sigma Chemicals, St. Louis, MO, USA), and CAT activity (Activity kit, Cayman chemicals, Ann Abror, MI, USA) were analyzed spectrophotometrically according to methods described by the manufacturers. SOD activity was measured as the conversion of nitroblue tetrazolium (NBT) to NBT-diformazan according to the vendor’s protocol (R&D Systems). The extent of reduction in the appearance of NBT-formazan was used as a measure of SOD activity present in the plasma.