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Introduction to Oxidative (Eu)stress in Exercise Physiology
Published in James N. Cobley, Gareth W. Davison, Oxidative Eustress in Exercise Physiology, 2022
Gareth W. Davison, James N. Cobley
Hydroxyl radicals can be formed in various ways in vivo with homolytic and heterolytic bond fission of water being well-known sources (Halliwell and Gutteridge, 2015). However, the most widely known mechanism of hydroxyl radical formation in an aqueous biological system is the transition metal-catalysed decomposition of and H2O2.
The Use of Brain Slices in the Study of Free Radical Actions
Published in Avital Schurr, Benjamin M. Rigor, BRAIN SLICES in BASIC and CLINICAL RESEARCH, 2020
During cellular respiration, oxygen is reduced to water by the acceptance of four electrons. Because of spin restriction on the electrons, however, oxygen usually accepts a single electron at a time. Addition of a single electron to oxygen produces the superoxide radical anion, . Fridovich11 has proposed that superoxide is a major factor in the toxicity of oxygen. Addition of a second electron results in the formation of hydrogen peroxide, H2O2. The dismutation of superoxide to hydrogen peroxide can occur spontaneously or can be catalyzed by the enzyme superoxide dismutase. Since peroxide has no unpaired electrons, it is not technically a free radical. It is a stable compound that can diffuse for long distances in a cellular system. However, when peroxide encounters transition metals such as ferrous or cuprous ions, it readily accepts an electron to produce the hydroxyl free radical, OH. The reaction of peroxide with iron to produce hydroxyl radicals is known as the Fenton reaction. The hydroxyl radical is an extremely reactive compound that quickly oxidizes almost any organic molecule it encounters and is considered to be the most damaging of the reactive oxygen intermediates.
Basic Principles in Photomedicine and Photochemistry
Published in Henry W. Lim, Nicholas A. Soter, Clinical Photomedicine, 2018
Electron transfer from excited state chromophores to molecules in the tissue, especially to oxygen, can also result in cell damage. The product of electron transfer to oxygen is superoxide anion, ., and a cation radical of the dye (Eq. 9). Superoxide anion is not very reactive toward biomolecules and can be removed by the enzyme superoxide dismutase contained in many cells and interstitial fluids. Superoxide anion can be converted into a highly reactive hydroxyl radical, OH., with the aid of a transition metal catalyst. Hydroxyl radical is highly reactive and causes damage almost indiscriminately to all biomolecules. Thus, its lifetime is very short and it can only react with molecules very close to the site where it is generated. Hydroxyl radical is an important toxic species for the effects of ionizing radiation on cells.
Removal of malathion insecticide from aqueous solution by the integration of persulfate process and magnetite nanoparticles loaded on carbon (Fe3O4@CNT) in the presence of ultraviolet radiation
Published in Toxin Reviews, 2022
Malektaj Eskandari makvand, Sima Sabzalipour, Mahboobeh Cheraghia, Neda Orak
A chemical oxidant is often utilized in the advanced oxidation processes to produce and activate twice as radicals and remove the organic compounds. Accordingly, the hydroxyl radical (HO) is a strong oxidant (E0 = 2.7V) agent in advanced oxidation. In this regard, there are various methods to produce the hydroxyl radicals, including photochemical, electrochemical, and chemical processes (Mahamuni and Adewuyi 2010, Asghar et al.2015). Today, the production of sulfate radicals (SO4-0) for destructing environmental pollutants has attracted a great deal of scientific attention. In this regard, the sulfate radical is a strong oxidant with E = 2.5–3.1V, produced by activating iron nanoparticles (Fe3O4 iron nanocomposite) or persulfate (Jaafarzadeh et al.2015).
Acute toxicity studies and protective effects of Cinnamon cassia bark extract in streptozotocin-induced diabetic rats
Published in Drug and Chemical Toxicology, 2022
K. Vijayakumar, R. L. Rengarajan, N. Suganthi, B. Prasanna, S. Velayuthaprabhu, M. Shenbagam, A. Vijaya Anand
Similarly, Table 5 shows the antioxidant activity of C. cassia bark extracts on H2O2. The maximum inhibition of H2O2 was seen in 1500 μg/mL of 65.98%, 90.03%, 75.45%, and 90.23% of aqueous, ethanol, methanol, and ascorbic acid, and their IC50 values are 1050 μg/mL, 800 μg/mL, 900 μg/mL, and 750 μg/mL. Compared to aqueous and methanol extract, the ethanolic extract of C. cassia has a better inhibitory activity. H2O2, a non-reactive molecule, forms a toxic molecule called hydroxyl radicals. This hydroxyl radical damages the cell membrane and leads to degenerative diseases. The extracts of C. cassia have a high donating ability, and thereby, it neutralizes the H2O2 into water.
Comparison of properties of dust in alveolar of rats and the workplace
Published in Experimental Lung Research, 2021
Xu Zhang, Zheng Zhang, Peng Wang, Shuyu Xiao, Ke Han, Yali Tang, Heliang Liu, Yuping Bai, Yulan Jin, Jinlong Li, Xiaoming Li, Qingan Xia, Fuhai Shen
Free radicals played an essential role in dust-induced macrophage damage and pulmonary fibrosis.20 However, Hydroxyl radicals were the most harmful and toxic free radicals in reactive oxygen species.21 Hydroxyl radicals caused oxidative damage to nucleic acids, proteins, and lipids through electron transfer, addition, and dehydrogenation, resulting in cell necrosis.21 The results of this study showed that the amount of hydroxy radicals released by dust from lung lavage was higher than that from the workplace. In animal experiments, the hydroxyl free radicals released by dust in the 8-week group were the most. Therefore, we speculated that dust had the highest surface activity in the eighth week after it entered the body. Reducing the amount of hydroxyl radicals produced by dust entering the human body through drugs or other therapeutic measures might delay the progress of pneumoconiosis.