A new method for the quantification of superoxide dismutase mimics with an allopurinol–xanthine oxidase–lucigenin enhanced system

Abstract

Allopurinol is a prodrug converted to oxypurinol by xanthine oxidase, a process followed by an efficient enzyme inhibition. Using a lucigenin-enhanced chemiluminescence method, we found that, under alkaline conditions, superoxide radicals are produced in large amounts in the first step of the interaction between the enzyme and the inhibitor. A comparison between lucigenin and cytochrome c as final detectors revealed that only the chemiluminescence technique is able to detect the superoxide anions from allopurinol oxidation. The allopurinol-xanthine oxidase-lucigenin system can be used for the quantification of various free-radical scavengers, in particular superoxide dismutase mimics. Three manganese compounds from different structural classes [manganese(II) chloride, manganese N,N'-bis(salicylidiene)ethylenediamine chloride, and manganese(III) meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin] were compared at five concentrations (0.01, 0.1, 1, 10, and 100 μM). The method is fast, 16 times more sensitive than the cytochrome c assay at pH 10.1 and could be used for in vivo investigations avoiding the lucigenin redox cycle. If the concentrations of the reagents are increased and Tween 20 is added, the method is also operative at pH 7.4.

On the vasoprotective mechanisms underlying novel β-phosphorylated nitrones: Focus on free radical characterization, scavenging and NO-donation in a biological model of oxidative stress

“…The antioxidant properties of PPNs were assessed using three standard assays, i.e., scavenging of 1,1'-diphenyl-2-picrylhydrazyl (DPPH) in methanol, determination of the total reactive antioxidant potential (TRAP) in DMSO (2%)-supplemented Tris-HCl 13 buffer (pH 7.4) and quenching of O 2 . -in glycine buffer (pH 10) [41][42][43]. As most PPNs did not yield PPNs-OOH EPR signals upon xanthine oxidase-based generation of O 2 .…”

Ultrasensitive Glutathione Detection Based on Lucigenin Cathodic Electrochemiluminescence in the Presence of MnO2 Nanosheets

“…Therefore, the inhibition effect of Mn 2+ on lucigenin ECL can be attributed to the reactive oxygen species scavenging property of Mn 2+ . 35 Different from fluorescent detection based on fluorescence resonance energy transfer between MnO 2 nanosheets and fluorescent materials, this ECL inhibition method relies on the electrochemical reaction mechanism. (1)…”

Algicidal Efficiency and Genotoxic Effects of Phanerochaete chrysosporium against Microcystis aeruginosa

“…SOD is a protective antioxidant enzyme that is induced during cellular antioxidant defenses and protects cells by scavenging harmful reactive oxygen species (ROS) [30,31]. POD is an integral part of the plant antioxidant system, and plays an important role in plant stress resistance physiology, which has the effect of removes oxygen free radicals and hydrogen peroxide [32]. MDA [33], which is the final product of membrane lipid decomposition, is an important biochemical indicator of oxidative membrane damage, and can reflect the degree of injury suffered by a plant.…”