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Cardiovascular Disease and Oxidative Stress
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
Marco Fernandes, Alisha Patel, Holger Husi
Xanthine oxidase (XO), a form of xanthine oxidoreductase, is important in the catabolism process of purines such as uric acid (UA) (Schuchardt et al., 2017). It readily donates electrons to diatomic oxygen yielding O2− and H2O2. UA is the final end-product of the purine catabolism and is formed from xanthines and hypoxanthines, and XO may be responsible for most of the ROS production (Berry and Hare, 2004). The catalytic reaction on how it generates ROS is shown in three separate, but relatable chemical reactions: Xanthine + NAD+ + H2O ↔ urate + NADHHypoxanthine + NAD+ + H2O ↔ xanthine + NADHXanthine + H2O + O2 ↔ urate + H2O2
Antioxidant or pro-oxidant? The effects of boron compounds on Saccharomyces cerevisiae BY4741 strain
Published in Preparative Biochemistry & Biotechnology, 2021
Berna Kavakcıoğlu Yardımcı, Zehra Mollaoğlu
A colorimetric assay kit (Cayman, Ann Arbor, MI) was used to measure superoxide dismutase (SOD; EC 1.15.1.1) activity in cell lysates following the instructions of the manufacturer. The activity measurement method is based on the detection of superoxide radicals generated by hypoxanthine and xanthine oxidase (XO) along with the use of tetrazolium salt (WST). Briefly, cell lysates were mixed with WST and XO solutions included in the kit and incubated for 30 min at room temperature with gentle shaking. After incubation period, the absorbance values were measured at 450 nm. SOD activity of the samples was calculated by using the equation obtained from the linear regression of the standard curve. One unit (U) was defined as the amount of enzyme needed to exhibit 50% dismutation of the superoxide radical.
Obtainment of an enriched fraction of Inga edulis: identification using UPLC-DAD-MS/MS and photochemopreventive screening
Published in Preparative Biochemistry & Biotechnology, 2020
Georgia de Assis Dias Alves, Daniele Fernandes da Silva, Thainá Venteu Teixeira, Rebeca Oliveira de Souza, Hervé Rogez, Maria José Vieira Fonseca
In the xanthine/XOD/luminol system, the XOD catalyzes the oxidation of hypoxanthine to xanthine and subsequently to uric acid (UA). The xanthine/XOD reaction produces the superoxide radical, which oxidizes the luminol. The luminol returns to the basal state and emits light, which is detected by equipment. The scavenging of the superoxide radicals by the samples lead to a decrease in the chemiluminescence since the amount of light emitted is proportional to the amount of superoxide radical that is free in the reaction medium.[41,42] The EC50 values for extract and fraction were 0.229 ± 0.018 and 0.186 ± 0.011 μg/mL, respectively. Cecropia obtusa and Byrsonima crassifolia are plants with known photoprotective effect. For these plants, the EC50 for the DPPH• was lower than the values found for I. edulis (1.83 and 1.82 µg/mL for C. obtusa and B. crassifolia, respectively). However, the EC50 for I. edulis in the xanthine/XOD/luminol system was similar to the EC50 for C. obtusa and B. crassifolia, (0.34 and 0.23 µg/mL, respectively). Therefore, although I. edulis presented a lower scavenging capacity of DPPH•, it showed scavenging capacity of the superoxide radical similar to C. obtusa and B. crassifolia.[43,44]
Influences of simulated gastrointestinal environment on physicochemical properties of gold nanoparticles and their implications on intestinal epithelial permeability
Published in Journal of Environmental Science and Health, Part C, 2019
Xiumei Jiang, Xiaowei Zhang, Patrick Gray, Jiwen Zheng, Timothy R. Croley, Peter P. Fu, Jun-Jie Yin
The peroxidase-like activities of Au NPs in three GIT fluids were measured in the presence of H2O2 by electron spin resonance (ESR) spectroscopy coupled with spin trapping agent BMPO. ESR spectra of the spin adduct of BMPO and hydroxyl radical, with relative intensity of 1:2:2:1, were recorded. The superoxide anion scavenging activities of Au NPs before and after incubation in GIT fluids were also measured by ESR. The xanthine/xanthine oxidase (XAN/XOD) reaction was applied to generate O2·－. Au NPs of 5 nm were preincubated in GIT fluids or ddH2O for 2 h before added into the XAN/XOD reaction. An aliquot of sample solution (50 µl) was loaded into quartz capillary tubes and inserted into the ESR cavity for spectra collection. The ESR spectra were recorded after 1 min of reaction. The ESR settings for the BMPO/·OH and BMPO/·OOH measurements are 1 G field modulation, 100 G scan range, and 20 mW microwave power.