Статті в журналах: "Active oxidants"

1

Guo, Mian, Yong-Min Lee, Shunichi Fukuzumi, and Wonwoo Nam. "Biomimetic metal-oxidant adducts as active oxidants in oxidation reactions." Coordination Chemistry Reviews 435 (May 2021): 213807. http://dx.doi.org/10.1016/j.ccr.2021.213807.

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Wu, Ru Feng, You Cheng Xu, Zhenyi Ma, Fiemu E. Nwariaku, George A. Sarosi, and Lance S. Terada. "Subcellular targeting of oxidants during endothelial cell migration." Journal of Cell Biology 171, no. 5 (December 5, 2005): 893–904. http://dx.doi.org/10.1083/jcb.200507004.

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Endogenous oxidants participate in endothelial cell migration, suggesting that the enzymatic source of oxidants, like other proteins controlling cell migration, requires precise subcellular localization for spatial confinement of signaling effects. We found that the nicotinamide adenine dinucleotide phosphate reduced (NADPH) oxidase adaptor p47phox and its binding partner TRAF4 were sequestered within nascent, focal complexlike structures in the lamellae of motile endothelial cells. TRAF4 directly associated with the focal contact scaffold Hic-5, and the knockdown of either protein, disruption of the complex, or oxidant scavenging blocked cell migration. An active mutant of TRAF4 activated the NADPH oxidase downstream of the Rho GTPases and p21-activated kinase 1 (PAK1) and oxidatively modified the focal contact phosphatase PTP-PEST. The oxidase also functioned upstream of Rac1 activation, suggesting its participation in a positive feedback loop. Active TRAF4 initiated robust membrane ruffling through Rac1, PAK1, and the oxidase, whereas the knockdown of PTP-PEST increased ruffling independent of oxidase activation. Our data suggest that TRAF4 specifies a molecular address within focal complexes that is targeted for oxidative modification during cell migration.

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3

Wu, Chiung-Ta, Chen-Yu Chang, Yi-Ying Li, and Po-Hsiung Lin. "Feasibility study for the production of multi-oxidants from the desalination of seawater brine." Water Quality Research Journal 54, no. 3 (September 20, 2018): 242–48. http://dx.doi.org/10.2166/wcc.2018.160.

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Abstract The primary goals of this study are to compare the efficiency of multiple oxidants that are produced using different commercially available anodes and separators and to optimize the reaction conditions for the recovery of multiple oxidants from brine. The brine produced in the desalination plants in Taiwan is the concentrated seawater that is recovered after the reverse osmosis process. The main component in the solution is NaCl. On average, chlorine concentration is approximately 3–5% by weight, which is slightly higher than the concentration for normal seawater. This concentrated brine can be used as raw material for the electrolyte to extract mixed disinfectant solutions. This study uses different catalytic electrolyzers to compare the efficiency with which multiple oxidants are produced using anodes that are coated in precious metal. A ruthenium-coated titanium anode generates the largest amount of active chlorine (chlorine dioxide). In terms of the diaphragms that are tested, the DuPont Nafion NE-2030 ion film produces active chlorine most efficiently. If no other chemicals are added to the brine (salinity 11.3%), Cl2 (302–376 mg L−1) is the primary oxidant generated from the original brine, and ClO2 (3.7–7.2 mg L−1) is the minor product in batch electrolysis. This article has been made Open Access thanks to the kind support of CAWQ/ACQE (https://www.cawq.ca).

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4

Kamceva, Gordana, Zorica Arsova-Sarafinovska, Tatjana Ruskovska, Milka Zdravkovska, Lidija Kamceva-Panova, and Elisaveta Stikova. "Cigarette Smoking and Oxidative Stress in Patients with Coronary Artery Disease." Open Access Macedonian Journal of Medical Sciences 4, no. 4 (October 28, 2016): 636–40. http://dx.doi.org/10.3889/oamjms.2016.117.

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AIM: To determine whether cigarette smoking, as a risk factor for CAD, affects oxidative stress.MATERIAL AND METHODS: The study included patients with CAD divided according to smoking status and number of cigarettes smoked during a whole day. In all subjects were examined biological markers of oxidative stress (concentration of oxidants and activity of antioxidant enzymes).RESULTS: The study included 300 patients with CAD, with an average age of 62.97 ± 11.18 years, with a predominance of males. Of the total, 34.0% were active smokers, and 43.0% were non-smokers. The number of the most active smokers smoked cigarettes 1-20/day. In terms of concentration of oxidants (MDA and HP) it has not proved a significant difference between smokers versus non-smokers. Over the activity of antioxidant enzymes (SOD, CAT and GPX) statistically significant difference was found in the activity of GPX and among active smokers with CAD and non-smokers with CAD (p = 0.039).CONCLUSION:Smoking as a risk factor for CAD is closely associated with increased oxidative stress and the number of cigarettes smoked plays an important role in increasing the level of oxidative damage and reduced antioxidant defence.AIM: To determine whether cigarette smoking, as a risk factor for CAD, affects (anti)oxidant status.MATERIAL AND METHODS: The study included patients with CAD, divided according to their smoking status and the number of cigarettes smoked during a day. Biological markers of oxidative stress (concentration of oxidants and activity of antioxidant enzymes) were measured in all subjects.RESULTS: The study included 300 patients with CAD, (average age of 63 ± 11 years), predominantly males. Of the total, 34.0% were active smokers, 23.0% were former smokers, and 43.0% were non-smokers. Most of the active smokers smoked 1-20 cigarettes/day. In terms of concentration of oxidants (MDA and HP) there was not a significant difference between smokers versus non-smokers. As for the activity of antioxidant enzymes (SOD, CAT and GPX), a statistically significant difference was found in the activity of GPX among the active smokers with CAD and the non-smokers with CAD (p = 0.039). CONCLUSION: Smoking as a risk factor for CAD is closely associated with increased oxidative stress, and the number of cigarettes smoked plays an important role in increasing the level of oxidative damage and reducing antioxidant defence.

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5

Jang, Jaeyoun, Myoseon Jang, Wilton Mui, Carrie A. Delcomyn, Michael V. Henley, and John D. Hearn. "Formation of Active Chlorine Oxidants in Saline-Oxone Aerosol." Aerosol Science and Technology 44, no. 11 (September 30, 2010): 1018–26. http://dx.doi.org/10.1080/02786826.2010.507612.

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6

Collman, James P., Allis S. Chien, Todd A. Eberspacher, and John I. Brauman. "Multiple Active Oxidants in Cytochrome P-450 Model Oxidations." Journal of the American Chemical Society 122, no. 45 (November 2000): 11098–100. http://dx.doi.org/10.1021/ja000961d.

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7

Patel, K. D., G. A. Zimmerman, S. M. Prescott, R. P. McEver, and T. M. McIntyre. "Oxygen radicals induce human endothelial cells to express GMP-140 and bind neutrophils." Journal of Cell Biology 112, no. 4 (February 15, 1991): 749–59. http://dx.doi.org/10.1083/jcb.112.4.749.

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The initial step in extravasation of neutrophils (polymorphonuclear leukocytes [PMNs]) to the extravascular space is adherence to the endothelium. We examined the effect of oxidants on this process by treating human endothelial cells with H2O2, t-butylhydroperoxide, or menadione. This resulted in a surface adhesive for PMN between 1 and 4 h after exposure. The oxidants needed to be present only for a brief period at the initiation of the assay. Adhesion was an endothelial cell-dependent process that did not require an active response from the PMN. The adhesive molecule was not platelet-activating factor, which mediates PMN adherence when endothelial cells are briefly exposed to higher concentrations of H2O2 (Lewis, M. S., R. E. Whatley, P. Cain, T. M. McIntyre, S. M. Prescott, and G. A. Zimmerman. 1988. J. Clin. Invest. 82:2045-2055), nor was it ELAM-1, an adhesive glycoprotein induced by cytokines. Oxidant-induced adhesion did not require protein synthesis, was inhibited by antioxidants, and, when peroxides were the oxidants, was inhibited by intracellular iron chelators. Granule membrane protein-140 (GMP-140) is a membrane-associated glycoprotein that can be translocated from its intracellular storage pool to the surface of endothelial cells where it acts as a ligand for PMN adhesion (Geng, J.-G., M. P. Bevilacqua, K. L. Moore, T. M. McIntyre, S. M. Prescott, J. M. Kim, G. A. Bliss, G. A. Zimmerman, and R. P. McEver. 1990. Nature (Lond). 343:757-760). We found that endothelial cells exposed to oxidants expressed GMP-140 on their surface, and that an mAb against GMP-140 or solubilized GMP-140 completely blocked PMN adherence to oxidant-treated endothelial cells. Thus, exposure of endothelial cells to oxygen radicals induces the prolonged expression of GMP-140 on the cell surface, which results in enhanced PMN adherence.

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8

Talukder, Saranika, Kendra L. Kerrisk, Gianfranco Gabai, and Pietro Celi. "Role of oxidant–antioxidant balance in reproduction of domestic animals." Animal Production Science 57, no. 8 (2017): 1588. http://dx.doi.org/10.1071/an15619.

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Reproductive process leads to dynamic changes in metabolism and energy consumption, which may be responsible for the excessive production of free radicals (oxidants) that are generated during the physiological process of oxygen consumption. As the ovary is a metabolically active organ, it produces oxidants. Growing follicles, granulose cells of Graffian follicles and ovulated follicles all produce both enzymatic and non-enzymatic antioxidants to preserve themselves from the oxidative damage of oxidants. Oxidants and antioxidants are involved in several reproductive functions such as the regulation of follicular fluid environment, folliculogenesis, steroidogenesis, corpus luteum function, and luteolysis. In this article, the currently available literature is reviewed in relation to the roles of oxidants and oxidative stress in both normal and abnormal reproductive physiological processes.

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9

Nalian, Armen, and Alexei V. Iakhiaev. "Possible mechanisms contributing to oxidative inactivation of activated protein C: Molecular dynamics study." Thrombosis and Haemostasis 100, no. 07 (2008): 18–25. http://dx.doi.org/10.1160/th07-12-0750.

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SummaryActivated protein C (APC) is a serine protease, an effector enzyme of the natural anticoagulant pathway. APC is approved for treatment of severe sepsis characterized by the increased concentrations of H2O2 and hypochlorite. We found that treatment of APC with these oxidants markedly inhibits the cleavage of the APC-specific chromogenic substrate, suggesting that oxidants can induce changes in the structure of the active site of APC. Resistance of oxidant-treated APC to chemical digestion with cyanogen bromide (CNBr) implies that methionine oxidation can at least in part be responsible for inhibition of APC. Since methionine residues, the main targets of oxidants in APC, are not included in the active site, we hypothesize that oxidation induces allosteric changes in the architecture of the catalytic triad of APC. Using molecular dynamics (MD) simulations we found that methionine oxidation alters the distance between cSer 195Oγ and cHis57 Nε2 atoms placing them in positions unfavorable for the catalysis. At the same time, neither distances between Cα atoms of the catalytic triad cAsp102-cHis57-cSer195, nor the overall structure of APC changed significantly after oxidation of the methionine residues. Disruption of the H-bond between Nδ1 of cHis57 and carboxyl group of cAsp 102, which can take place during the hypochlorite-induced modification of cHis57,dramatically changed the architecture of the catalytic triad in oxidized APC. This mechanism could contribute to APC inactivation by hypochlorite concurrently with methionine oxidation. These are novel findings, which describe potentially pathophysiologically relevant changes in the functional stability of APC exposed to the oxidative stress.

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10

Pardini, Ronald S. "Toxicity of oxygen from naturally occurring redox-active pro-oxidants." Archives of Insect Biochemistry and Physiology 29, no. 2 (1995): 101–18. http://dx.doi.org/10.1002/arch.940290203.

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11

Zhang, Yue, and Xuan J. Wang. "The Preparation of Graphite Oxide Controlled by Optimum Oxidation Potential with any Rejected Nitro-Oxidizer." Nano 14, no. 02 (February 2019): 1950018. http://dx.doi.org/10.1142/s1793292019500188.

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Nitro-oxidizers (nitric acid-27S, nitrogen tetroxide and mixed nitrogen oxide) are common liquid oxidants widely used in liquid rockets and missile weapons. How to deal with large quantities of scrapped nitro-oxidizers is a complex, costly and dangerous project. We pretreated it with hydrogen peroxide (H2O[Formula: see text] and converted the active oxidant component of nitro-oxidizers into nitric acid, which can be used as oxidant source to prepare graphite oxide from natural graphite. The comprehensive oxidation ability of the reaction system can be effectively controlled by adding different volumes of H2O2, and the oxidation ability can be expressed by the redox potential of the system. Combined with FT-IR, Raman and XRD characterization analysis, the optimal redox potential interval, [1700, 1800][Formula: see text]mV, has been determined for the synthesis of graphite oxide. With the help of data interpolation and function nonlinear fitting and the initial potential of rejected nitro-oxidants obtained, the composition ratio of nitric acid and nitrogen tetroxide (N2O[Formula: see text] has been preliminarily determined with the optimum amount of H2O2. Furthermore, the optimum oxidizing atmosphere for the synthesis of graphite oxide can be formed in spite of a wide range of concentrations of oxidant components, and the resulting graphite oxide has been proven to be a qualified and effective product.

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12

DUNCAN, Roger F., Hazel PETERSON, Curt H. HAGEDORN, and Alex SEVANIAN. "Oxidative stress increases eukaryotic initiation factor 4E phosphorylation in vascular cells." Biochemical Journal 369, no. 2 (January 15, 2003): 213–25. http://dx.doi.org/10.1042/bj20020435.

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Dysregulated cell growth can be caused by increased activity of protein synthesis eukaryotic initiation factor (eIF) 4E. Dysregulated cell growth is also characteristic of atherosclerosis. It is postulated that exposure of vascular cells, such as endothelial cells, smooth muscle cells and monocytes/macrophages, to oxidants, such as oxidized low-density lipoprotein (oxLDL), leads to the elaboration of growth factors and cytokines, which in turn results in smooth muscle cell hyperproliferation. To investigate whether activation of eIF4E might play a role in this hyperproliferative response, vascular cells were treated with oxLDL, oxidized lipid components of oxLDL and several model oxidants, including H2O2 and dimethyl naphthoquinone. Exposure to each of these compounds led to a dose- and time-dependent increase in eIF4E phosphorylation in all three types of vascular cells, correlated with a modest increase in overall translation rate. No changes in eIF4EBP, eIF2 or eIF4B modification state were observed. Increased eIF4E phosphorylation was paralleled by increased presence of eIF4E in high-molecular-mass protein complexes characteristic of its most active form. Anti-oxidants at concentrations typically employed to block oxidant-induced cell signalling likewise promoted eIF4E phosphorylation. The results of this study indicate that increased eIF4E activity may contribute to the pathophysiological events in early atherogenesis by increasing the expression of translationally inefficient mRNAs encoding growth-promoting proteins.

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13

Elstner, Erich F. "Hämaktivierte Oxidationen mit dem Chlorit-Sauerstoff-Komplex „TCDO" (OXOFERIN®) - eine Übersicht / Heme-Activated Oxidations by the Chlorite-Oxygen Complex "TCDO" (OXOFERIN®)." Zeitschrift für Naturforschung C 43, no. 11-12 (December 1, 1988): 893–902. http://dx.doi.org/10.1515/znc-1988-11-1216.

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Abstract Several chlorooxygen compounds, hydrogen peroxide and reducing molecules in the presence of chelated iron (Fenton systems) are oxidants of biological relevance. These compounds are either produced in living tissues or are in use as desinfectants or drugs. Tetrachlorodecaoxide as the active principle in the drug OXOFËRIN® can be differentiated from the above mentioned oxidants by means of simple biochemical test systems where different activators and detector molecules are used.

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14

Mishra, B., P. A. Hassan, K. I. Priyadarsini, and Hari Mohan. "Reactions of Biological Oxidants with Selenourea: Formation of Redox Active Nanoselenium." Journal of Physical Chemistry B 109, no. 26 (July 2005): 12718–23. http://dx.doi.org/10.1021/jp051328n.

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15

Ghosh, Anindya, Filipe Tiago de Oliveira, Toshihiro Yano, Takanori Nishioka, Evan S. Beach, Isamu Kinoshita, Eckard Münck, Alexander D. Ryabov, Colin P. Horwitz та Terrence J. Collins. "Catalytically Active μ-Oxodiiron(IV) Oxidants from Iron(III) and Dioxygen". Journal of the American Chemical Society 127, № 8 (березень 2005): 2505–13. http://dx.doi.org/10.1021/ja0460458.

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16

Collman, James P., Li Zeng, and Richard A. Decréau. "Multiple active oxidants in competitive epoxidations catalyzed by porphyrins and corroles." Chem. Commun., no. 24 (2003): 2974–75. http://dx.doi.org/10.1039/b310763a.

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17

Higuchi, H., I. Kurose, D. Fukumura, H. J. Yan, H. Saito, S. Miura, R. Hokari, et al. "Active oxidants mediate IFN-alpha-induced microvascular alterations in rat mesentery." Journal of Immunology 158, no. 10 (May 15, 1997): 4893–900. http://dx.doi.org/10.4049/jimmunol.158.10.4893.

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Abstract The present study was designed to investigate the influences of IFN-alpha on the microcirculatory hemodynamics. The mesenteric microcirculation of male Wistar rats was observed through an intravital fluorescence microscopic system. The leukocyte behavior, RBC velocity, and albumin leakage were monitored simultaneously before and after a continuous infusion of IFN-alpha. In other rats, the oxidant-sensitive fluorescence probe dihydrorhodamine-123 (DHR) fluorescence was observed in the same set up. Administration of IFN-alpha increased the number of adherent and emigrated leukocytes and decreased the RBC velocity in mesenteric venules. Oxidative stress indicated by DHR fluorescence was exacerbated in microvessels of IFN-alpha-treated rats. Following the leukocyte recruitment and oxidative stress, an exaggerated albumin leakage was observed. Thrombus formation in venules and hemorrhage along venules were frequently observed in rats treated with IFN-alpha. N,N'-dimethylthiourea, a scavenger of hydrogen peroxide and a hydroxyl radical, largely prevented these microvascular responses. Pretreatment of rats with mAb directed against either CD18 or ICAM-1 also attenuated the IFN-alpha-induced microvascular alterations. It is concluded, therefore, that a high concentration of IFN-alpha stimulates CD18/ICAM-1-dependent adhesive interactions with endothelial cells and oxidant production of leukocytes, which leads to microcirculatory derangements characterized by decreased barrier function and reduced anticoagulant activity of venular endothelial cells.

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18

Bedekar, V., S. V. Chavan, and A. K. Tyagi. "Highly sinter-active nanocrystalline RE2O3 (RE = Gd, Eu, Dy) by a combustion process, and role of oxidant-to-fuel ratio in preparing their different crystallographic modifications." Journal of Materials Research 22, no. 3 (March 2007): 587–94. http://dx.doi.org/10.1557/jmr.2007.0101.

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Highly sinter-active powders of RE2O3 [rare earth (RE) = Gd, Eu, Dy] have been prepared using the corresponding metal nitrates as the oxidants, and glycine and citric acid as the fuels. Two different oxidant-to-fuel ratios, namely stoichiometric ratio and fuel-deficient ratio were used to explore the possibility of preparing different crystallographic modifications. By a careful control of oxidant-to-fuel ratio, nanocrystalline Eu2O3 and Gd2O3 could be prepared in cubic (C-type) as well as monoclinic (B-type) modifications. However, the high-temperature monoclinic modification could not be obtained for Dy2O3 due to a very high C-to-B-type phase transition temperature. The crystallite size, surface area, and sintering behavior were also studied for powders prepared using different oxidant-to-fuel ratios, and the results showed a remarkable correlation between different fuel contents and powder properties. Some of these powders resulted in pellets of nearly theoretical density. The sintered microstructure was studied by scanning electron microscopy.

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19

Wu, Chiung-Ta, Chen-Yu Chang, Yi-Ying Li, Yu-Lun Kuan, and Po-Hsiung Lin. "An efficiency analysis for the production of chlorine dioxide by the electrolysis of brine in seawater desalination plants." Water Quality Research Journal 54, no. 2 (September 20, 2018): 127–33. http://dx.doi.org/10.2166/wcc.2018.257.

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Abstract A previous study by the authors evaluated the efficiency of producing multi-oxidants using anodes coated in precious metal. This study showed that a titanium anode coated in ruthenium generates the largest amount of active chlorine (chlorine dioxide). The results from the efficiency evaluation also show that DuPont Nafion N-2030 ion film is the most efficient of the diaphragms that were tested. To increase the recovery rate for ClO2, this study optimizes the composition of the anode electrolyte. Sodium chlorite is added into the brine and an electrolysis reaction is performed at 40 °C and 12 V for batch operation. The principal product is ClO2 with a maximum concentration of 1,074 mg L−1. During continuous electrolysis, when the inflow rate for the anode electrolyte is increased to 120 mL min−1, ClO2 is produced at a constant concentration of 60 mg L−1 after 30 minutes. An analysis of the multi-oxidants generated from brine to detect disinfection byproducts shows very little trichloromethane is formed, much less than the standard for total trihalomethanes in drinking water in Taiwan (0.1 mg L−1). The disinfection efficiency of the multi-oxidant produced in this study is about three times greater than that of commercial hypochlorous acid. These results show that multi-oxidant products retrieved by recycling brine from desalination plants are commercially applicable and have economic value.

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20

Cummings, Jeffrey L. "Anti-dementia drugs: what difference do they make?" Reviews in Clinical Gerontology 8, no. 4 (November 1998): 279–80. http://dx.doi.org/10.1017/s0959259898008417.

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Alzheimer’s disease (AD) is a treatable disorder. Two classes of anti-dementia agents have emerged in the recent past: anti-oxidants and cholinesterase inhibitors. A recent study showed that the anti-oxidants alpha tocopherol (vitamin E) and selegiline slowed the progress of AD. Patients treated with either agent alone or with both agents in combination progressed to end-point more slowly than patients on placebo. Patients on placebo reached one of the end-points - death, nursing home placement, progression to severe AD, or significant loss of activities of daily living - in approximately 400 days, whereas patients on active agent required approximately 600 days to reach the same end-points. Both these agents have anti-oxidant properties; selegiline is a monoamine oxidase-B inhibitor that reduces free radical generation and alpha tocopherol has free radical capture capabilities. These agents are applied to patients in mild or moderate phases of AD, where slowing the progression of the illness and maintenance of patients at higher levels of function are the principal goals. Slowing the progression of the disease in more advanced phases of the illness may be less desirable.

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Jing, Yan, Min Wu, Andrew A. Wong, Eric M. Fell, Shijian Jin, Daniel A. Pollack, Emily F. Kerr, Roy G. Gordon, and Michael J. Aziz. "In situ electrosynthesis of anthraquinone electrolytes in aqueous flow batteries." Green Chemistry 22, no. 18 (2020): 6084–92. http://dx.doi.org/10.1039/d0gc02236e.

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We demonstrate the electrochemical oxidation of an anthracene derivative to a redox-active anthraquinone at room temperature in a flow cell without the use of hazardous oxidants or noble metal catalysts.

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22

Schellhorn, Herb E., and Hosni M. Hassan. "Response of hydroperoxidase and superoxide dismutase deficient mutants of Escherichia coli K-12 to oxidative stress." Canadian Journal of Microbiology 34, no. 10 (October 1, 1988): 1171–76. http://dx.doi.org/10.1139/m88-206.

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In Escherichia coli, the coordinate action of two antioxidant enzymes, superoxide dismutase and hydroperoxidase (catalase), protect the cell from the deleterious effects of oxyradicals generated during normal aerobic respiration. To evaluate the relative importance of these two classes of enzymes, strains of E. coli deficient in superoxide dismutase and (or) hydroperoxidase were constructed by generalized transduction and their physiological responses to oxygen and oxidant stress examined. Superoxide dismutase was found to be more important than hydroperoxidase in preventing oxygen-dependent growth inhibition and mutagenesis, and in reducing sensitivity to redox-active compounds known to generate the superoxide anion. However, both types of enzymes were required for an effective defense against chemical oxidants that generate superoxide radicals and hydrogen peroxide.

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23

Manos, Donatos, Foteini Papadopoulou, Antigoni Margellou, Dimitrios Petrakis, and Ioannis Konstantinou. "Heterogeneous Activation of Persulfate by LaMO3 (M=Co, Fe, Cu, Mn, Ni) Perovskite Catalysts for the Degradation of Organic Compounds." Catalysts 12, no. 2 (February 2, 2022): 187. http://dx.doi.org/10.3390/catal12020187.

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Sulfate radical-based advanced oxidation processes (SR-AOPs) are lately applied for the degradation of various pollutants through the formation of reactive oxidant species (ROS) from activation of oxidants, such as persulfate (PS) or peroxymonosulfate (PMS). In this study, LaMO3 (M=Co, Fe, Cu, Mn, Ni) perovskite catalysts were synthesized, characterized by several techniques, and tested for the activation of persulfate towards the degradation of phenolic pollutants. The effect of substitution of position B of La-based perovskites as well as calcination temperature was studied. Overall, the results showed that the decisive role in the catalytic activity was the presence of structures that enhance the transfer of electrons between perovskite and oxidant. LaNiO3 followed by LaCoO3 were found as the most active catalysts. Finally, the stability of the catalysts was studied, showing that B-metal leaching is significant for both catalysts, with LaCoO3 being the most stable one.

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24

Van der Vliet, Albert, Mai N. Nguyen, Mark K. Shigenaga, Jason P. Eiserich, Gregory P. Marelich, and Carroll E. Cross. "Myeloperoxidase and protein oxidation in cystic fibrosis." American Journal of Physiology-Lung Cellular and Molecular Physiology 279, no. 3 (September 1, 2000): L537—L546. http://dx.doi.org/10.1152/ajplung.2000.279.3.l537.

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Cystic fibrosis (CF) is associated with chronic pulmonary inflammation and progressive lung dysfunction, possibly associated with the formation of neutrophil myeloperoxidase (MPO)-derived oxidants. Expectorated sputum specimens from adult CF patients were analyzed for MPO characteristic protein modifications and found to contain large amounts of active MPO as well as high levels of protein-associated 3-chlorotyrosine and 3,3′-dityrosine, products that result from MPO activity, compared with expectorated sputum from non-CF subjects. Sputum levels of nitrite (NO2−) and nitrate (NO3−), indicating local production of nitric oxide (NO·), were not elevated but in fact were slightly reduced in CF. However, there was a slight increase in protein-associated 3-nitrotyrosine in CF sputum compared with controls, reflecting the formation of reactive nitrogen intermediates, possibly through MPO-catalyzed oxidation of NO2−. CF sputum MPO was found to contribute to oxidant-mediated cytotoxicity toward cultured tracheobronchial epithelial cells; however, peroxidase-dependent protein oxidation occurred primarily within sputum proteins, suggesting scavenging of MPO-derived oxidants by CF mucus and perhaps formation of secondary cytotoxic products within CF sputum. Our findings demonstrate the formation of MPO-derived oxidizing and possibly nitrating species within the respiratory tract of subjects with CF, which collectively may contribute to bronchial injury and respiratory failure in CF.

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Vlahou, Eftihia, Stefania Christofi, Ioannis G. Roussis, and Stamatina Kallithraka. "Browning Development and Antioxidant Compounds in White Wines after Selenium, Iron, and Peroxide Addition." Applied Sciences 12, no. 8 (April 11, 2022): 3834. http://dx.doi.org/10.3390/app12083834.

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The effect of oxidation on the organoleptic properties of white wines mostly involves increased browning color, loss of the fruity aromas, and appearance of unpleasant odors. Browning, however, is known to be related with polyphenol oxidation and therefore it may be delayed by the presence of antioxidants such as selenium (Se) and SO2. On the other hand, the presence of oxidants such as metal ions and H2O2 can accelerate browning and oxidation phenomena. The browning capacity, the phenolic composition (both total and individual contents of flavanols and hydroxycinnamic acids), the antioxidant activity, and the SO2 content of Assyrtiko white wines were studied after the addition of Fe2+ and H2O2 and Se at two temperatures, employing an accelerated test. Browning was approached from a kinetic point of view, and the study was focused on the implication of oxidants and antioxidants on browning rate, paying particular attention to the content of major redox-active polyphenols, including substances with an o-diphenol feature, such as flavanols and hydroxycinnamic acids. The results showed that after the addition of oxidants it was possible to significantly accelerate the rate of browning development (up to 4.7 and six times) depending on the temperature and the concentration of the added compounds. The presence of Se protected wine color and preserved total SO2 at 35 °C, while at 50 °C, these effects were not observed. Total flavanol content decreased upon heating, while total hydroxycinnamic content showed a slight increase. Similarly, the content of the individual phenolic compounds (with the exception of caffeic acid and (+)-catechin at 35 °C) was decreased with oxidant addition, while Se addition was not adequate to prevent or even promote their oxidation.

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Sedenkova, Kseniya N., Kristian S. Andriasov, Tamara S. Kuznetsova, and Elena B. Averina. "Oxyfunctionalization of CH2-Group Activated by Adjacent Three-Membered Ring." Current Organic Synthesis 15, no. 4 (June 12, 2018): 515–32. http://dx.doi.org/10.2174/1570179415666180405113158.

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Background: Increasing use of the three-membered ring in drug development initiates the search for efficient methods of transformations of cyclopropane derivatives. Oxidation of methylene group activated by an adjacent cyclopropane represents a direct approach towards carbonylcyclopropanes, allows avoiding unnecessary synthetic stages and meets the requirements of atom economy. Objective: In this review all available data concerning the oxidation of cyclopropane-containing hydrocarbons and their functionally substituted derivatives are systematized, and the general regularities between the structure of the starting compound, the oxidant employed and the reaction outcome are underlined. Conclusion: The following regularities were distinguished for the oxidation of cyclopropane-containing compounds into cyclopropylketones. The main structural parameters of the starting compounds, which influence the distribution of the oxidation products, are the followings: the presence of competing C-H bonds, flexibility or rigidity of structure, electron and sterical substituents effects. A number of preparative methods of activated C(sp3)-H bonds oxygenation were elaborated, employing such powerful oxidants as ozone, dioxiranes, CrO3 and a variety of catalytic systems, based on transition metals. For the oxidation of cyclopropane derivatives all these oxidants may be employed. RuO4, generated in situ, usually behaves as selective and soft oxidant. TFDO often demonstrates lesser selectivity, but it may be the best choice when several activated CH2 groups should be oxidised. In the case of dihalocyclopropanes the use of CrO3 is preferable. Summarily, the oxidation of methylene group adjacent to cyclopropane has been undoubtedly developed into a reliable preparative approach to cyclopropylketones, which should find an active use in synthetic organic chemistry.

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Meena, Raghunandan, Omji Porwal, Vijay Kumar Tilak, Rajeshwar Kamal Kant Arya, and Ram Chand Dhakar. "Pharmacological Application of Moringa oleifera: A Mini Review." International Journal of Medical Sciences and Pharma Research 6, no. 1 (March 15, 2020): 1–3. http://dx.doi.org/10.22270/ijmspr.v6i1.25.

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All part of the Moringa tree is useful in some way and people depends on it for their livelihood. Oral diseases persist to be a major health problem all over the world. Various microorganisms are found to be the possible pathogens responsible for the oral diseases. The leaves of the Moringa tree are an excellent source of Nutrients like Minerals, Protein and Vitamins (A and C). Moringa tree has approximately 46 antioxidants and it is one of the cheapest sources of natural anti-oxidants. Anti-oxidants supply the free atoms needed by the human body and mitigate the effect of free radicals. M. oleifera contains active compounds such as flavonoids, tannins, saponins, alkaloids, phenolics, and triterpenoids which possess antibacterial effects. Moringa oleifera has high mineral and protein content and has been previously investigated for its potential in treating different oral soft tissue diseases. This review explores the various pharmacological application of Moringa oleifera Keywords: Moringa oleifera, Anti-oxidants, Minerals, Vitamins

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Meena, Raghunandan, Sunil Kumar Prajapati, Rajendra Nagar, Omji Porwal, Teena Nagar, Vijay Kumar Tilak, R. Jayakumararaj, Rajeshwar Kamal Kant Arya, and Ram Chand Dhakar. "Application of Moringa oleifera in Dentistry." Asian Journal of Dental and Health Sciences 1, no. 1 (December 25, 2021): 10–13. http://dx.doi.org/10.22270/ajdhs.v1i1.5.

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Анотація:

All part of the Moringa tree is useful in some way and people depends on it for their livelihood. Oral diseases persist to be a major health problem all over the world. Various microorganisms are found to be the possible pathogens responsible for the oral diseases. The leaves of the Moringa tree are an excellent source of Nutrients like Minerals, Protein and Vitamins (A and C). Moringa tree has approximately 46 antioxidants and it is one of the cheapest sources of natural anti-oxidants. Anti-oxidants supply the free atoms needed by the human body and mitigate the effect of free radicals. M. oleifera contains active compounds such as flavonoids, tannins, saponins, alkaloids, phenolics, and triterpenoids which possess antibacterial effects. Moringa oleifera has high mineral and protein content and has been previously investigated for its potential in treating different oral soft tissue diseases. Present review summarises the various application of Moringa oleifera in the field of dentistry. Keywords: Moringa oleifera, Anti-oxidants, Oral diseases, dentistry

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Khubutiya, Mogely S., Vladimir A. Kolesnikov, Anatoly K. Evseev, Alexander G. Volkov, Mikhail M. Abakumov, Alexander N. Shibaev, and Mark M. Goldin. "Electrochemical Synthesis of Oxidants in Dilute Sulfate Solutions and Active Oxygen Donor Determination." ECS Transactions 11, no. 21 (December 19, 2019): 51–58. http://dx.doi.org/10.1149/1.2928906.

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Reid, MB. "Reactive Oxygen and Nitric Oxide in Skeletal Muscle." Physiology 11, no. 3 (June 1, 1996): 114–19. http://dx.doi.org/10.1152/physiologyonline.1996.11.3.114.

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Skeletal muscle produces oxygen radicals, nitric oxide, and a variety of redox-active derivatives that modulate muscle function under physiological conditions. In unfatigued muscle, reactive oxygen intermediates and nitric oxide exert opposing effects on excitation-contraction coupling. During strenuous exercise, oxidants accumulate in the tissue and accelerate the fatigue process.

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Thiere, Alexandra, Hartmut Bombach, and Michael Stelter. "The Behavior of Ruthenium in Copper Electrowinning." Metals 12, no. 8 (July 27, 2022): 1260. http://dx.doi.org/10.3390/met12081260.

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The recycling of material containing precious metals can lead to the entry of ruthenium into the copper electrowinning process, by so far unknown effects. There, ruthenium is oxidized to highly volatile ruthenium tetroxide. In order to avoid ruthenium losses during electrolysis, the oxidation behavior of ruthenium in copper electrowinning was investigated by testing different oxygen overvoltages using lead alloy and diamond anodes. Furthermore, the temperature and the current density were varied to investigate a possible chemical or electrochemical reaction. The results of the study show that ruthenium is not directly electrochemically oxidized to ruthenium tetroxide at the anode. Especially at anodes with high oxygen overvoltage, the formation of other oxidants occurs parallel to the oxygen evolution in the electrolyte. These oxidants oxidize ruthenium compounds to highly volatile ruthenium tetroxide by chemical reactions. These reactions depend mainly on temperature; the formation of the active oxidants depends on the anodic potential. To avoid ruthenium losses in the copper electrowinning process, anodes with a low anodic potential should be used at low electrolyte temperatures.

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Rahman, Habibur. "Analytical Applications of Permanganate as an Oxidant in the Determination of Pharmaceuticals Using Chemiluminescence and Spectrophotometry: A Review." Current Analytical Chemistry 16, no. 6 (August 13, 2020): 670–86. http://dx.doi.org/10.2174/1573411015666190617103833.

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Background: Potassium permanganate is a green and versatile industrial oxidizing agent. Due to its high oxidizing ability, it has received considerable attention and has been extensively used for many years for the synthesis, identification, and determination of inorganic and organic compounds. Objective: Potassium permanganate is one of the most applicable oxidants, which has been applied in a number of processes in several industries. Furthermore, it has been widely used in analytical pharmacy to develop analytical methods for pharmaceutically active compounds using chemiluminescence and spectrophotometric techniques. Results: This review covers the importance of potassium permanganate over other common oxidants used in pharmaceuticals and reported its extensive use and analytical applications using direct, indirect and kinetic spectrophotometric methods in different pharmaceutical formulations and biological samples. Chemiluminescent applications of potassium permanganate in the analyses of pharmaceuticals using flow and sequential injection techniques are also discussed. Conclusion: This review summarizes the extensive use of potassium permanganate as a chromogenic and chemiluminescent reagent in the analyses of pharmaceutically active compounds to develop spectrophotometric and chemiluminescence methods since 2000.

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Massima Mouele, Emile Salomon, Mihaela Dinu, Franscious Cummings, Ojo O. Fatoba, Myo Tay Zar Myint, Htet Htet Kyaw, Anca C. Parau, et al. "Effect of Calcination Time on the Physicochemical Properties and Photocatalytic Performance of Carbon and Nitrogen Co-Doped TiO2 Nanoparticles." Catalysts 10, no. 8 (July 28, 2020): 847. http://dx.doi.org/10.3390/catal10080847.

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The application of highly active nano catalysts in advanced oxidation processes (AOPs) improves the production of non-selective hydroxyl radicals and co-oxidants for complete remediation of polluted water. This study focused on the synthesis and characterisation of a highly active visible light C–N-co-doped TiO2 nano catalyst that we prepared via the sol-gel method and pyrolysed at 350 °C for 105 min in an inert atmosphere to prevent combustion of carbon moieties. Then we prolonged the pyrolysis holding time to 120 and 135 min and studied the effect of these changes on the crystal structure, particle size and morphology, electronic properties and photocatalytic performance. The physico-chemical characterisation proved that alteration of pyrolysis holding time allows control of the amount of carbon in the TiO2 catalyst causing variations in the band gap, particle size and morphology and induced changes in electronic properties. The C–N–TiO2 nano composites were active under both visible and UV light. Their improved activity was ascribed to a low electron–hole pair recombination rate that enhanced the generation of OH· and related oxidants for total deactivation of O.II dye. This study shows that subtle differences in catalyst preparation conditions affect its physico-chemical properties and catalytic efficiency under solar and UV light.

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MINETTI, Maurizio, Donatella PIETRAFORTE, A. M. Michela DI STASI, and Cinzia MALLOZZI. "Nitric oxide-dependent NAD linkage to glyceraldehyde-3-phosphate dehydrogenase: possible involvement of a cysteine thiyl radical intermediate." Biochemical Journal 319, no. 2 (October 15, 1996): 369–75. http://dx.doi.org/10.1042/bj3190369.

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Previous studies have demonstrated that glyceraldehyde-3-phosphate dehydrogenase (GAPDH) undergoes NAD(H) linkage to an active site thiol when it comes into contact with •NO-related oxidants. We found that a free-radical generator 2,2´-azobis-(2-amidinopropane) hydrochloride (AAPH), which does not release either •NO or •NO-related species, was indeed able to induce the NAD(H) linkage to GAPDH. We performed spin-trapping studies with purified apo-GAPDH to identify a putative thiol intermediate produced by AAPH as well as by •NO-related oxidants. As •NO sources we used •NO gas and two •NO-donors, S-nitroso-N-acetyl-D,L-penicillamine and 3-morpholinosydnonimine hydrochloride (SIN-1). Because SIN-1 produces •NO and a superoxide radical simultaneously, we also tested the effects of peroxynitrite. All the •NO-related oxidants were able to induce the linkage of NAD(H) to GAPDH and the formation of a protein free-radical identified as a thiyl radical (inhibited by N-ethylmaleimide). •NO gas and the •NO-donors required molecular oxygen to induce the formation of the GAPDH thiyl radical, suggesting the possible involvement of higher nitrogen oxides. Thiyl radical formation was decreased by the reconstitution of GAPDH with NAD+. Apo-GAPDH was a strong scavenger of AAPH radicals, but its scavenging ability was decreased when its cysteine residues were alkylated or when it was reconstituted with NAD+. In addition, after treatment with AAPH, a thiyl radical of GAPDH was trapped at high enzyme concentrations. We suggest that the NAD(H) linkage to GAPDH is mediated by a thiyl radical intermediate not specific to •NO or •NO-related oxidants. The cysteine residue located at the active site of GAPDH (Cys-149) is oxidized by free radicals to a thiyl radical, which reacts with the neighbouring coenzyme to form Cys-NAD(H) linkages. Studies with the NAD+ molecule radiolabelled in the nicotinamide or adenine portion revealed that both portions of the NAD+ molecule are linked to GAPDH.

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Dong, Hongyu, Yang Li, Shuchang Wang, Weifan Liu, Gongming Zhou, Yifan Xie, and Xiaohong Guan. "Both Fe(IV) and Radicals Are Active Oxidants in the Fe(II)/Peroxydisulfate Process." Environmental Science & Technology Letters 7, no. 3 (February 12, 2020): 219–24. http://dx.doi.org/10.1021/acs.estlett.0c00025.

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Pacheco, Juliana da Silva, and Raquel Elisa da Silva-Lopez. "Study of the Proteolytic Activity of the Tropical Legume Crotalaria spectabilis." Zeitschrift für Naturforschung C 67, no. 9-10 (October 1, 2012): 495–509. http://dx.doi.org/10.1515/znc-2012-9-1008.

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The characterization of legume proteases contributes to the understanding of the physiology of plants and their interaction with the environment. Thirteen extracts from various parts of Crotalaria spectabilis were made using different extraction systems. The highest protein content was found in seeds, and the most pronounced proteolytic activity was observed in leaf extracts, with an optimal pH value in the alkaline range. Proteases in extracts from roots, stems, and fl owers were active in various pH ranges. Proteases in all extracts were maximally active between 30 °C and 60 °C and were thermostable (24 h, 60 °C). Hemoglobin, bovine serum albumin, casein, and gelatin were hydrolyzed by C. spectabilis extracts in different ways. The highest serine protease activity was found in leaves. Seeds contained high levels of serine proteases and low levels of cysteine proteases. Flowers, roots, and stems contained different levels of serine, aspartic, and metalloproteases, respectively. The proteolytic activities in extracts were modulated by cations and oxidants to various degrees. C. spectabilis proteases are differentially expressed in distinctive organs, and their stability against heat and oxidants makes this plant an important source of stable proteases

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BECKMAN, KENNETH B., and BRUCE N. AMES. "The Free Radical Theory of Aging Matures." Physiological Reviews 78, no. 2 (April 1, 1998): 547–81. http://dx.doi.org/10.1152/physrev.1998.78.2.547.

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Beckman, Kenneth B., and Bruce N. Ames. The Free Radical Theory of Aging Matures. Physiol. Rev. 78: 547–581, 1998. — The free radical theory of aging, conceived in 1956, has turned 40 and is rapidly attracting the interest of the mainstream of biological research. From its origins in radiation biology, through a decade or so of dormancy and two decades of steady phenomenological research, it has attracted an increasing number of scientists from an expanding circle of fields. During the past decade, several lines of evidence have convinced a number of scientists that oxidants play an important role in aging. (For the sake of simplicity, we use the term oxidant to refer to all “reactive oxygen species,” including O−2⋅, H2O2, and ⋅OH, even though the former often acts as a reductant and produces oxidants indirectly.) The pace and scope of research in the last few years have been particularly impressive and diverse. The only disadvantage of the current intellectual ferment is the difficulty in digesting the literature. Therefore, we have systematically reviewed the status of the free radical theory, by categorizing the literature in terms of the various types of experiments that have been performed. These include phenomenological measurements of age-associated oxidative stress, interspecies comparisons, dietary restriction, the manipulation of metabolic activity and oxygen tension, treatment with dietary and pharmacological antioxidants, in vitro senescence, classical and population genetics, molecular genetics, transgenic organisms, the study of human diseases of aging, epidemiological studies, and the ongoing elucidation of the role of active oxygen in biology.

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Lind, SE, JR McDonagh, and CJ Smith. "Oxidative inactivation of plasmin and other serine proteases by copper and ascorbate." Blood 82, no. 5 (September 1, 1993): 1522–31. http://dx.doi.org/10.1182/blood.v82.5.1522.1522.

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Abstract Fibrin thrombi form at sites of injury, where leukocytes release a variety of oxidants. To determine whether oxidants might affect proteins of the fibrinolytic system, we examined the effects of various oxidants on plasmin. Plasmin was not inhibited by micromolar concentrations of hypochlorous acid, chloramine T, or H2O2. Neither Fe nor Cu affected plasmin alone or in the presence of H2O2. However, incubation of plasmin with 5 mumol/L Cu(I or II) in the presence of the reducing agent ascorbic acid resulted in a loss of its hydrolytic activity towards proteins as well as towards small synthetic substrates. The addition of EDTA, but not mannitol, prevented its inactivation. Inactivation was prevented by the addition of catalase and accelerated by hydrogen peroxide. Preincubation of plasmin with the competitive inhibitor alpha-N-acetyl-L-lysine methyl ester prevented inactivation by Cu(II) and ascorbate. These results together suggest site-specific oxidation of plasmin's active site. Treatment of the plasminogen activators tissue plasminogen activator and two-chain urokinase-type plasminogen activator, as well as trypsin, neutrophil elastase, and thrombin with Cu(II) and ascorbate resulted in a loss of their amidolytic and proteolytic activity, indicating the general susceptibility of serine proteases to this type of oxidation. Oxidation of the zymogens Glu-plasminogen and single-chain urokinase-type plasminogen activator by Cu(II) and ascorbate resulted in the failure of these molecules to generate active enzymes when treated with plasminogen activators or plasmin, respectively. The active site His residue may be the target of oxidative inactivation, as evidenced by the partial protection afforded plasmin by the addition of Zn(II), histidine, or the platinum derivative, platinum(II) (2,2′:6′,2″- terpyridine) chloride. Because platelets contain micromolar concentrations of Cu and leukocytes are rich in ascorbate, Cu-dependent site-specific oxidation might play a role in modulating proteolytic events and the life span of thrombi formed at sites of tissue injury.

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Lind, SE, JR McDonagh, and CJ Smith. "Oxidative inactivation of plasmin and other serine proteases by copper and ascorbate." Blood 82, no. 5 (September 1, 1993): 1522–31. http://dx.doi.org/10.1182/blood.v82.5.1522.bloodjournal8251522.

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Анотація:

Fibrin thrombi form at sites of injury, where leukocytes release a variety of oxidants. To determine whether oxidants might affect proteins of the fibrinolytic system, we examined the effects of various oxidants on plasmin. Plasmin was not inhibited by micromolar concentrations of hypochlorous acid, chloramine T, or H2O2. Neither Fe nor Cu affected plasmin alone or in the presence of H2O2. However, incubation of plasmin with 5 mumol/L Cu(I or II) in the presence of the reducing agent ascorbic acid resulted in a loss of its hydrolytic activity towards proteins as well as towards small synthetic substrates. The addition of EDTA, but not mannitol, prevented its inactivation. Inactivation was prevented by the addition of catalase and accelerated by hydrogen peroxide. Preincubation of plasmin with the competitive inhibitor alpha-N-acetyl-L-lysine methyl ester prevented inactivation by Cu(II) and ascorbate. These results together suggest site-specific oxidation of plasmin's active site. Treatment of the plasminogen activators tissue plasminogen activator and two-chain urokinase-type plasminogen activator, as well as trypsin, neutrophil elastase, and thrombin with Cu(II) and ascorbate resulted in a loss of their amidolytic and proteolytic activity, indicating the general susceptibility of serine proteases to this type of oxidation. Oxidation of the zymogens Glu-plasminogen and single-chain urokinase-type plasminogen activator by Cu(II) and ascorbate resulted in the failure of these molecules to generate active enzymes when treated with plasminogen activators or plasmin, respectively. The active site His residue may be the target of oxidative inactivation, as evidenced by the partial protection afforded plasmin by the addition of Zn(II), histidine, or the platinum derivative, platinum(II) (2,2′:6′,2″- terpyridine) chloride. Because platelets contain micromolar concentrations of Cu and leukocytes are rich in ascorbate, Cu-dependent site-specific oxidation might play a role in modulating proteolytic events and the life span of thrombi formed at sites of tissue injury.

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Yamada, T., C. Volkmer, and MB Grisham. "Antioxidant Properties of 5-ASA: Potential Mechanism for Its Anti-Inflammatory Activity." Canadian Journal of Gastroenterology 4, no. 7 (1990): 295–302. http://dx.doi.org/10.1155/1990/324287.

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There is a growing body of experimental data to suggest that the inflamed intestine and/or colon may be subjected to considerable oxidative stress. The most probable source of these oxidants are the phagocytic leukocytes, since these cells are present in large numbers in the inflamed mucosa and are known to produce significant amounts of potentially injurious reactive oxygen species in response to inflammatory stimuli. The authors' laboratory and others have demonstrated that 5-aminosalicylic acid (5-ASA) possesses potent antioxidant activity, including free radical scavenging properties and the ability to decompose neutrophilic oxidants (eg, hypochlorous acid) and detoxify hemoprotein-associated oxidizing agents. 5-ASA has the additional property of being able to chelate iron and render it poorly redox active. Therefore, it is proposed that much of the anti-inflammatory activity of 5-ASA may be due to its numerous antioxidant properties.

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Lalmanach, Gilles, Ahlame Saidi, Paul Bigot, Thibault Chazeirat, Fabien Lecaille, and Mylène Wartenberg. "Regulation of the Proteolytic Activity of Cysteine Cathepsins by Oxidants." International Journal of Molecular Sciences 21, no. 6 (March 12, 2020): 1944. http://dx.doi.org/10.3390/ijms21061944.

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Besides their primary involvement in the recycling and degradation of proteins in endo-lysosomal compartments and also in specialized biological functions, cysteine cathepsins are pivotal proteolytic contributors of various deleterious diseases. While the molecular mechanisms of regulation via their natural inhibitors have been exhaustively studied, less is currently known about how their enzymatic activity is modulated during the redox imbalance associated with oxidative stress and their exposure resistance to oxidants. More specifically, there is only patchy information on the regulation of lung cysteine cathepsins, while the respiratory system is directly exposed to countless exogenous oxidants contained in dust, tobacco, combustion fumes, and industrial or domestic particles. Papain-like enzymes (clan CA, family C1, subfamily C1A) encompass a conserved catalytic thiolate-imidazolium pair (Cys25-His159) in their active site. Although the sulfhydryl group (with a low acidic pKa) is a potent nucleophile highly susceptible to chemical modifications, some cysteine cathepsins reveal an unanticipated resistance to oxidative stress. Besides an introductory chapter and peculiar attention to lung cysteine cathepsins, the purpose of this review is to afford a concise update of the current knowledge on molecular mechanisms associated with the regulation of cysteine cathepsins by redox balance and by oxidants (e.g., Michael acceptors, reactive oxygen, and nitrogen species).

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Zima, Alexandra M., Oleg Y. Lyakin, Roman V. Ottenbacher, Konstantin P. Bryliakov, and Evgenii P. Talsi. "Iron-Catalyzed Enantioselective Epoxidations with Various Oxidants: Evidence for Different Active Species and Epoxidation Mechanisms." ACS Catalysis 7, no. 1 (December 3, 2016): 60–69. http://dx.doi.org/10.1021/acscatal.6b02851.

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McKenzie, S. M., W. F. Doe, and G. D. Buffinton. "5-Aminosalicylic acid prevents oxidant mediated damage of glyceraldehyde-3-phosphate dehydrogenase in colon epithelial cells." Gut 44, no. 2 (February 1, 1999): 180–85. http://dx.doi.org/10.1136/gut.44.2.180.

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BackgroundReactive oxygen and nitrogen derived species produced by activated neutrophils have been implicated in the damage of mucosal proteins including the inhibition of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in the active inflammatory lesion in patients with inflammatory bowel disease (IBD). This study investigated the efficacy of currently used IBD therapeutics to prevent injury mediated by reactive oxygen and nitrogen derived species.MethodsGAPDH activity of human colon epithelial cells was used as a sensitive indicator of injury produced by reactive oxygen and nitrogen derived species. HCT116 cells (106/ml phosphate buffered saline; 37°C) were incubated in the presence of 5-aminosalicylic acid (5-ASA), 6-mercaptopurine, methylprednisolone, or metronidazole before exposure to H2O2, HOCl, or NO in vitro. HCT116 cell GAPDH enzyme activity was determined by standard procedures. Cell free reactions between 5-ASA and HOCl were analysed by spectrophotometry and fluorimetry to characterise the mechanism of oxidant scavenging.ResultsGAPDH activity of HCT116 cells was inhibited by the oxidants tested: the concentration that produced 50% inhibition (IC50) was 44.5 (2.1) μM for HOCl, 379.8 (21.3) μM for H2O2, and 685.8 (103.8) μM for NO (means (SEM)). 5-ASA was the only therapeutic compound tested to show efficacy (p<0.05) against HOCl mediated inhibition of enzyme activity; however, it was ineffective against H2O2 and NO mediated inhibition of GAPDH. Methylprednisolone, metronidazole, and the thiol-containing 6-mercaptopurine were ineffective against all oxidants. Studies at ratios of HOCl:5-ASA achievable in the mucosa showed direct scavenging to be the mechanism of protection of GAPDH activity. Mixing 5-ASA and HOCl before addition to the cells resulted in significantly greater protection of GAPDH activity than when HOCl was added to cells preincubated with 5-ASA. The addition of 5-ASA after HOCl exposure did not restore GAPDH activity.ConclusionsTherapies based on 5-ASA may play a direct role in scavenging the potent neutrophil oxidant HOCl, thereby protecting mucosal GAPDH from oxidative inhibition. These findings suggest that strategies for the further development of new HOCl scavenging compounds may be useful in the treatment of IBD.

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Zhang, Xing-Hai. "Article Commentary: Regulation of Protein Function by Residue Oxidation." Proteomics Insights 3 (January 2010): PRI.S3327. http://dx.doi.org/10.4137/pri.s3327.

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A majority of extant life forms require O2 to survive and thrive. Oxidation is inevitably one of the most active cellular processes and one constant challenge that living organisms must face. Generation of oxidants including reactive oxygen species is a natural consequence of cellular metabolism of all biological systems during normal life cycle under different environments. These oxidants oxidize many biological macromolecules such as proteins and affect their functions. Oxidation of specific amino acids in proteins may cause damage to protein structure and impair function, or may also activate protein activities and promote cellular metabolism. As an example, the reversible oxidation of cysteine and methionine residues has a profound impact on protein function and cellular process. A recent study that examines the effect of Met oxidation on Ser phosphorylation in a mitochondrial enzyme, pyruvate dehydrogenase, provides another demonstration that protein oxidation is an important regulatory mechanism for organisms to deal with developmental and environmental challenges throughout life processes.

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Gardner, Paul R. "Superoxide-Driven Aconitase FE-S Center Cycling." Bioscience Reports 17, no. 1 (February 1, 1997): 33–42. http://dx.doi.org/10.1023/a:1027383100936.

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O−2 produced by the autoxidation of respiratory chain electron carriers, and other cellular reductants, inactivates bacterial and mammalian iron-sulfur-containing (de)hydratases including the citric acid cycle enzyme aconitase. Release of the solvent-exposed iron atom and oxidation of the [4Fe-4S]2+ cluster accompanies loss of catalytic activity. Rapid reactivation is achieved by iron-sulfur cluster reduction and Fe2+ insertion. Inactivation-reactivation is a dynamic and cyclical process which modulates aconitase and (de)hydratase activities in Escherichia coli and mammalian cells. The balance of inactive and active aconitase provides a sensitive measure of the changes in steady-statO−2 levels occuring in living cells and mitochondria under stress conditions. Aconitases are also inactivated by other oxidants including O2, H2O2, NO., and ONOO− which are associated with inflammation, hyperoxia and other pathophysiological conditions. Loss of aconitase activity during oxidant stress may impair energy production, and the liberation of reactive iron may further enhance oxidative damage. Iron-sulfur center cycling may also serve adaptive functions by modulating gene expression or by signaling metabolic quiescence.

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46

Janes, Trevor, Pavel Zatsepin, and Datong Song. "Reactivity of heavy carbene analogues towards oxidants: a redox active ligand-enabled isolation of a paramagnetic stannylene." Chemical Communications 53, no. 21 (2017): 3090–93. http://dx.doi.org/10.1039/c7cc00837f.

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47

Singh, Rajat, Yongjun Wang, Jörn M. Schattenberg, Youqing Xiang, and Mark J. Czaja. "Chronic oxidative stress sensitizes hepatocytes to death from 4-hydroxynonenal by JNK/c-Jun overactivation." American Journal of Physiology-Gastrointestinal and Liver Physiology 297, no. 5 (November 2009): G907—G917. http://dx.doi.org/10.1152/ajpgi.00151.2009.

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Sustained activation of the c-Jun NH2-terminal kinase (JNK) signaling pathway mediates the development and progression of experimental diet-induced nonalcoholic fatty liver disease (NAFLD). Delineating the mechanism of JNK overactivation in the setting of a fatty liver is therefore essential to understanding the pathophysiology of NAFLD. Both human and experimental NAFLD are associated with oxidative stress and resultant lipid peroxidation, which have been proposed to mediate the progression of this disease from simple steatosis to steatohepatitis. The ability of oxidants and the lipid peroxidation product 4-hydroxynonenal (HNE) to activate JNK signaling suggested that these two factors may act synergistically to trigger JNK overactivation. The effect of HNE on hepatocyte injury and JNK activation was therefore examined in cells under chronic oxidant stress from overexpression of the prooxidant enzyme cytochrome P450 2E1 (CYP2E1), which occurs in NAFLD. CYP2E1-generated oxidant stress sensitized a rat hepatocyte cell line to death from normally nontoxic concentrations of HNE. CYP2E1-overexpressing cells underwent a more profound depletion of glutathione (GSH) in response to HNE secondary to decreased γ-glutamylcysteine synthetase activity. GSH depletion led to overactivation of JNK/c-Jun signaling at the level of mitogen-activated protein kinase kinase 4 that induced cell death. Oxidant stress and the lipid peroxidation product HNE cause synergistic overactivation of the JNK/c-Jun signaling pathway in hepatocytes, demonstrating that HNE may not be just a passive biomarker of hepatic oxidant stress but rather an active mediator of hepatocellular injury through effects on JNK signaling.

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48

Whidden, Melissa A., Joseph M. McClung, Darin J. Falk, Matthew B. Hudson, Ashley J. Smuder, W. Bradley Nelson, and Scott K. Powers. "Xanthine oxidase contributes to mechanical ventilation-induced diaphragmatic oxidative stress and contractile dysfunction." Journal of Applied Physiology 106, no. 2 (February 2009): 385–94. http://dx.doi.org/10.1152/japplphysiol.91106.2008.

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Respiratory muscle weakness resulting from both diaphragmatic contractile dysfunction and atrophy has been hypothesized to contribute to the weaning difficulties associated with prolonged mechanical ventilation (MV). While it is clear that oxidative injury contributes to MV-induced diaphragmatic weakness, the source(s) of oxidants in the diaphragm during MV remain unknown. These experiments tested the hypothesis that xanthine oxidase (XO) contributes to MV-induced oxidant production in the rat diaphragm and that oxypurinol, a XO inhibitor, would attenuate MV-induced diaphragmatic oxidative stress, contractile dysfunction, and atrophy. Adult female Sprague-Dawley rats were randomly assigned to one of six experimental groups: 1) control, 2) control with oxypurinol, 3) 12 h of MV, 4) 12 h of MV with oxypurinol, 5) 18 h of MV, or 6) 18 h of MV with oxypurinol. XO activity was significantly elevated in the diaphragm after MV, and oxypurinol administration inhibited this activity and provided protection against MV-induced oxidative stress and contractile dysfunction. Specifically, oxypurinol treatment partially attenuated both protein oxidation and lipid peroxidation in the diaphragm during MV. Further, XO inhibition retarded MV-induced diaphragmatic contractile dysfunction at stimulation frequencies >60 Hz. Collectively, these results suggest that oxidant production by XO contributes to MV-induced oxidative injury and contractile dysfunction in the diaphragm. Nonetheless, the failure of XO inhibition to completely prevent MV-induced diaphragmatic oxidative damage suggests that other sources of oxidant production are active in the diaphragm during prolonged MV.

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49

Poulos, Thomas L. "Intermediates in P450 catalysis." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 363, no. 1829 (April 15, 2005): 793–806. http://dx.doi.org/10.1098/rsta.2004.1537.

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Cytochromes P450 catalyse the insertion of one O 2 -derived oxygen atom in unactivated C–H bonds, and as such, are potent oxidants. A significant amount is known about the P450 catalytic cycle owing partly to the single heme group at the active site that provides spectroscopic handles in tracking various intermediates. A sophisticated array of electron paramagnetic, electron double nuclear resonance, and more traditional absorption spectroscopies have been able to identify key intermediates, while crystallography has defined the structure of the substrate-free, -bound, and oxy-complexes. What has remained elusive is the Fe(IV)=O intermediate, thought to be the active hydroxylating agent. Here, theory and especially density functional calculations have provided valuable insights.

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50

Quiñonez-Flores, Celia María, Susana Aideé González-Chávez, Danyella Del Río Nájera, and César Pacheco-Tena. "Oxidative Stress Relevance in the Pathogenesis of the Rheumatoid Arthritis: A Systematic Review." BioMed Research International 2016 (2016): 1–14. http://dx.doi.org/10.1155/2016/6097417.

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Rheumatoid arthritis (RA) is an autoimmune inflammatory disease whose pathogenic mechanisms remain to be elucidated. The oxidative stress and antioxidants play an important role in the disease process of RA. The study of oxidants and antioxidants biomarkers in RA patients could improve our understanding of disease pathogenesis; likely determining the oxidative stress levels in these patients could prove helpful in assessing disease activity and might also have prognostic implications. To date, the usefulness of oxidative stress biomarkers in RA patients is unclear and the evidence supporting them is heterogeneous. In order to resume and update the information in the status of oxidants and antioxidants and their connection as biomarkers in RA, we performed a systematic literature search in the PubMed database, including clinical trials published in the last five years using the word combination “rheumatoid arthritis oxidative stress”. In conclusion, this review supports the fact that the oxidative stress is an active process in RA pathogenesis interrelated to other better known pathogenic elements. However, some controversial results preclude a definite conclusion.

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