3 3 5 5 tetramethyl benzidine tmb hydrogen peroxide

3,3’,5,5’-Tetramethyl benzidine (TMB), hydrogen peroxide, isopropanol (IPA), dimethyl formamide (DMF), and phosphate citrate buffer (pH 5) were purchased from Sigma-Aldrich. Deionized water (0.055 μS) was used throughout this work. All chemicals were of analytical grade and were used as received without further purification.

The synthesis of DEQ (6-hydroxy-2,2,4-trimethyl-1,2-dihydroquinoline) was performed by the dealkylation of ethoxyquin exposed to hydrobromic acid [30 ] (Figure 1). The structure of DEQ was confirmed by nuclear magnetic resonance spectroscopy and chromatography-mass spectrometry. Phenazine methosulfate (PMS), reduced and oxidized forms of glutathione, nicotinamide adenine dinucleotide (NADH), and NADPH were purchased from AppliChem GmbH (Germany). Trichloroacetic acid (TCA), 5,5′-Dithiobis(2-nitrobenzoic acid) (DTNB), 1-chloro-2,4-dinitrobenzene (CDNB), 3,3′,5,5′-tetramethylbenzidine (TMB), hydrogen peroxide, and GR were purchased from Sigma-Aldrich (USA). Nitroblue tetrazolium (NBT) chloride was purchased from Alfa Aesar (UK).