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Koehn EM, Lang A, Flores A, Lambert C, Klinman J. Replacement of Tyrosines by Unnatural Amino Acid Aminophenylalanine Leads to Metal-Mediated Aniline Free Radical Formation in a Copper Amine Oxidase. ACS Chem Biol 2024; 19:1525-1532. [PMID: 38889186 DOI: 10.1021/acschembio.4c00198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/20/2024]
Abstract
Copper amine oxidases (CAOs) catalyze the oxidative deamination of primary amines to aldehyde, ammonia, and hydrogen peroxide as products and are widely distributed in bacteria, plants, and eukaryotes. These enzymes initiate the single turnover, post-translational conversion of an active site tyrosine to the redox cofactor 2,4,5-trihydroxyphenylalanine quinone (TPQ), subsequently employing TPQ to catalyze steady-state amine oxidation. The mechanisms of TPQ biogenesis and steady-state amine oxidation have been studied extensively, with consensus mechanisms proposed for both reactions. One unresolved issue has been whether the Cu2+ center must undergo formal reduction to Cu1+ in the course of the reaction. Herein, we investigate the properties of the active site of a yeast (Hansenula polymorpha) amine oxidase (HPAO) that has undergone site-specific insertion of a para-aminophenylalanine (pAF) into the position of either the precursor tyrosine to TPQ (Y405) or the two strictly conserved neighboring tyrosines (Y305 and Y407). While our original intention was to interrogate cofactor biogenesis using a precursor unnatural amino acid (UAA) of altered redox potential and pKa, we instead observe an unanticipated reaction assigned to an intramolecular electron transfer from pAF to the active site copper ion. We establish the generality of the observed active site chemistry using exogenously added, aniline-containing substrates under conditions that prevent side chain amine oxidation. The results support previous proposals that the activation of the TPQ precursor occurs in the absence of a formal valence change at the active site copper site. The described reaction of pAFs with the active site redox Cu2+ center of HPAO provides a prototype for either the engineering of the enzymatic oxidation of exogenous anilines or the insertion of site-specific free radical probes within proteins.
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Affiliation(s)
- Eric M Koehn
- Department of Chemistry and California Institute for Quantitative Biosciences, University of California-Berkeley, Berkeley, California 94720-3220, United States
| | - Albert Lang
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, California 94720-3220, United States
| | - Allison Flores
- Department of Chemistry and California Institute for Quantitative Biosciences, University of California-Berkeley, Berkeley, California 94720-3220, United States
| | - Claudia Lambert
- Department of Chemistry and California Institute for Quantitative Biosciences, University of California-Berkeley, Berkeley, California 94720-3220, United States
| | - Judith Klinman
- Department of Chemistry and California Institute for Quantitative Biosciences, University of California-Berkeley, Berkeley, California 94720-3220, United States
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, California 94720-3220, United States
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2
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Aldrich JL, Panicker A, Ovalle R, Sharma B. Drug Delivery Strategies and Nanozyme Technologies to Overcome Limitations for Targeting Oxidative Stress in Osteoarthritis. Pharmaceuticals (Basel) 2023; 16:1044. [PMID: 37513955 PMCID: PMC10383173 DOI: 10.3390/ph16071044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 06/26/2023] [Accepted: 07/12/2023] [Indexed: 07/30/2023] Open
Abstract
Oxidative stress is an important, but elusive, therapeutic target for osteoarthritis (OA). Antioxidant strategies that target oxidative stress through the elimination of reactive oxygen species (ROS) have been widely evaluated for OA but are limited by the physiological characteristics of the joint. Current hallmarks in antioxidant treatment strategies include poor bioavailability, poor stability, and poor retention in the joint. For example, oral intake of exogenous antioxidants has limited access to the joint space, and intra-articular injections require frequent dosing to provide therapeutic effects. Advancements in ROS-scavenging nanomaterials, also known as nanozymes, leverage bioactive material properties to improve delivery and retention. Material properties of nanozymes can be tuned to overcome physiological barriers in the knee. However, the clinical application of these nanozymes is still limited, and studies to understand their utility in treating OA are still in their infancy. The objective of this review is to evaluate current antioxidant treatment strategies and the development of nanozymes as a potential alternative to conventional small molecules and enzymes.
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Affiliation(s)
| | | | | | - Blanka Sharma
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611, USA; (J.L.A.)
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3
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Tama A, Bartosz G, Sadowska-Bartosz I. Phenolic compounds interfere in the Ampliflu Red/peroxidase assay for hydrogen peroxide. Food Chem 2023; 422:136222. [PMID: 37121205 DOI: 10.1016/j.foodchem.2023.136222] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 04/06/2023] [Accepted: 04/19/2023] [Indexed: 05/02/2023]
Abstract
Methods employing horseradish peroxidase (HRP) are popular for quantification of hydrogen peroxide. This communication reports interference of the Ampliflu Red-HRP assay by phenolic compounds, abundant in food and beverages of plant origin. Concentrations of catechin, propyl gallate, quercetin and gallic acid lowering the yield of the product, resorufin, in this system by 50% were lower than 10 μM. The extent of inhibition increased with decreasing hydrogen peroxide concentration. These results point to the necessity of a careful interpretation of results concerning the quantification of hydrogen peroxide in materials containing phenolic compounds with methods employing HRP, especially when low concentrations of hydrogen peroxide are concerned.
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Affiliation(s)
- Anna Tama
- Laboratory of Analytical Biochemistry, Institute of Food Technology and Nutrition, College of Natural Sciences, University of Rzeszow, 4 Zelwerowicza Street, 35-601 Rzeszow, Poland
| | - Grzegorz Bartosz
- Department of Bioenergetics, Food Analysis and Microbiology, Institute of Food Technology and Nutrition, College of Natural Sciences, University of Rzeszow, 4 Zelwerowicza Street, 35-601 Rzeszow, Poland.
| | - Izabela Sadowska-Bartosz
- Laboratory of Analytical Biochemistry, Institute of Food Technology and Nutrition, College of Natural Sciences, University of Rzeszow, 4 Zelwerowicza Street, 35-601 Rzeszow, Poland.
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4
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Schwaiger L, Zenone A, Csarman F, Ludwig R. Continuous photometric activity assays for lytic polysaccharide monooxygenase-Critical assessment and practical considerations. Methods Enzymol 2022; 679:381-404. [PMID: 36682872 DOI: 10.1016/bs.mie.2022.08.054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Lytic polysaccharide monooxygenase (LPMO) is a monocopper-dependent enzyme that cleaves glycosidic bonds by using an oxidative mechanism. In nature, they act in concert with cellobiohydrolases to facilitate the efficient degradation of lignocellulosic biomass. After more than a decade of LPMO research, it has become evident that LPMOs are abundant in all domains of life and fulfill a diverse range of biological functions. Independent of their biological function and the preferred polysaccharide substrate, studying and characterizing LPMOs is tedious and so far mostly relied on the discontinuous analysis of the solubilized reaction products by HPLC/MS-based methods. In the absence of appropriate substrates, LPMOs can engage in two off-pathway reactions, i.e., an oxidase and a peroxidase-like activity. These futile reactions have been exploited to set up easy-to-use continuous spectroscopic assays. As the natural substrates of newly discovered LPMOs are often unknown, widely applicable, simple, reliable, and robust spectroscopic assays are required to monitor LPMO expression and to perform initial biochemical characterizations, e.g., thermal stability measurements. Here we provide detailed descriptions and practical protocols to perform continuous photometric assays using either 2,6-dimethoxyphenol (2,6-DMP) or hydrocoerulignone as colorimetric substrates as a broadly applicable assay for a range of LPMOs. In addition, a turbidimetric measurement is described as the currently only method available to continuously monitor LPMOs acting on amorphous cellulose.
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Affiliation(s)
- Lorenz Schwaiger
- Department of Food Science and Technology, Institute of Food Technology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Alice Zenone
- Department of Food Science and Technology, Institute of Food Technology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Florian Csarman
- Department of Food Science and Technology, Institute of Food Technology, University of Natural Resources and Life Sciences, Vienna, Austria.
| | - Roland Ludwig
- Department of Food Science and Technology, Institute of Food Technology, University of Natural Resources and Life Sciences, Vienna, Austria
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Abstract
Lytic polysaccharide monooxygenases (LPMOs) are unique redox enzymes capable of disrupting the crystalline surfaces of industry-relevant recalcitrant polysaccharides, such as chitin and cellulose. Historically, LPMOs were thought to be slow enzymes relying on O2 as the co-substrate, but it is now clear that these enzymes prefer H2O2, allowing for fast depolymerization of polysaccharides through a peroxygenase reaction. Thus, quantifying H2O2 in LPMO reaction set-ups is of a great interest. The horseradish peroxidase (HRP)/Amplex Red (AR) assay is one of the most popular and accessible tools for measuring hydrogen peroxide. This assay has been used in various types of biological and biochemical studies, including LPMO research, but suffers from pitfalls that need to be accounted for. In this Chapter, we discuss this method and its use for assessing the often rate-limiting in situ formation of H2O2 in LPMO reactions. We show that, after accounting for multiple potential side reactions, quantitative data on H2O2 production obtained with the HRP/Amplex Red assay provide useful clues for understanding the catalytic activity of LPMOs, including the impact of reductants and transition metal ions.
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Affiliation(s)
- Anton A Stepnov
- Faculty of Chemistry, Biotechnology and Food Science, NMBU-Norwegian University of Life Sciences, Ås, Norway
| | - Vincent G H Eijsink
- Faculty of Chemistry, Biotechnology and Food Science, NMBU-Norwegian University of Life Sciences, Ås, Norway.
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Grabb KC, Pardis WA, Kapit J, Wankel SD, Hayden EB, Hansel CM. Design Optimization of a Submersible Chemiluminescent Sensor (DISCO) for Improved Quantification of Reactive Oxygen Species (ROS) in Surface Waters. SENSORS (BASEL, SWITZERLAND) 2022; 22:6683. [PMID: 36081142 PMCID: PMC9460491 DOI: 10.3390/s22176683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 08/30/2022] [Accepted: 08/31/2022] [Indexed: 06/15/2023]
Abstract
Reactive oxygen species (ROS) are key drivers of biogeochemical cycling while also exhibiting both positive and negative effects on marine ecosystem health. However, quantification of the ROS superoxide (O2-) within environmental systems is hindered by its short half-life. Recently, the development of the diver-operated submersible chemiluminescent sensor (DISCO), a submersible, handheld instrument, enabled in situ superoxide measurements in real time within shallow coral reef ecosystems. Here, we present a redesigned and improved instrument, DISCO II. Similar to the previous DISCO, DISCO II is a self-contained, submersible sensor, deployable to 30 m depth and capable of measuring reactive intermediate species in real time. DISCO II is smaller, lighter, lower cost, and more robust than its predecessor. Laboratory validation of DISCO II demonstrated an average limit of detection in natural seawater of 133.1 pM and a percent variance of 0.7%, with stable photo multiplier tube (PMT) counts, internal temperature, and flow rates. DISCO II can also be optimized for diverse environmental conditions by adjustment of the PMT supply voltage and integration time. Field tests showed no drift in the data with a percent variance of 3.0%. Wand tip adaptations allow for in situ calibrations and decay rates of superoxide using a chemical source of superoxide (SOTS-1). Overall, DISCO II is a versatile, user-friendly sensor that enables measurements in diverse environments, thereby improving our understanding of the cycling of reactive intermediates, such as ROS, across various marine ecosystems.
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Affiliation(s)
- Kalina C. Grabb
- MIT-WHOI Joint Program in Oceanography, Cambridge, MA 02139, USA
- Woods Hole Oceanographic Institution, Marine Chemistry and Geochemistry, Woods Hole, MA 02543, USA
| | - William A. Pardis
- Woods Hole Oceanographic Institution, Applied Ocean Physics and Engineering, Woods Hole, MA 02543, USA
| | - Jason Kapit
- Woods Hole Oceanographic Institution, Applied Ocean Physics and Engineering, Woods Hole, MA 02543, USA
| | - Scott D. Wankel
- Woods Hole Oceanographic Institution, Marine Chemistry and Geochemistry, Woods Hole, MA 02543, USA
| | - Eric B. Hayden
- Woods Hole Oceanographic Institution, Applied Ocean Physics and Engineering, Woods Hole, MA 02543, USA
| | - Colleen M. Hansel
- Woods Hole Oceanographic Institution, Marine Chemistry and Geochemistry, Woods Hole, MA 02543, USA
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Barrios-Maya MA, Ruiz-Ramírez A, Quezada H, Céspedes Acuña CL, El-Hafidi M. Palmitoyl-CoA effect on cytochrome c release, a key process of apoptosis, from liver mitochondria of rat with sucrose diet-induced obesity. Food Chem Toxicol 2021; 154:112351. [PMID: 34171418 DOI: 10.1016/j.fct.2021.112351] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 06/10/2021] [Accepted: 06/14/2021] [Indexed: 02/07/2023]
Abstract
Cytochrome c (cyt-c) release from the mitochondria to the cytosol is a key process in the initiation of hepatocyte apoptosis involved in the progression of non-alcoholic fatty liver disease (NAFLD) to fibrosis, cirrhosis and hepatocellular carcinoma. Hepatocyte apoptosis may be related to lipotoxicity due to the accumulation of palmitic acid and palmitoyl-CoA (Pal-CoA). Therefore, the aim of this study is to examine whether Pal-CoA induces cyt-c release from liver mitochondria of sucrose-fed rat (SF). Pal-CoA-induced cyt-c release was sensitive to cyclosporine A indicating the involvement of the mitochondrial membrane permeability transition (mMPT). In addition, cyt-c release from SF mitochondria remains significantly lower than C mitochondria despite the increased rate of H2O2 generation in SF mitochondria. The decreased cyt-c release from SF may be also related to the increased proportion of the palmitic acid-enriched cardiolipin, due to the high availibilty of palmitic acid in SF liver. The enrichment of cardiolipin molecular species with palmitic acid makes cardiolipin more resistant to peroxidation, a mechanism involved in the dissociation of cyt-c from mitochondrial inner membrane. These results suggest that Pal-CoA may participate in the progression of NAFLD to more severe disease through mechanisms involving cyt-c release and mMPT, a key process of apoptosis.
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Affiliation(s)
- Miguel-Angel Barrios-Maya
- Depto de Biomedicina Cardiovascular, Instituto Nacional de Cardiología Ignacio Chávez, Juan Badiano No 1, Colonia Sección XVI, Tlalpan, CP 14080, C.D. México, Mexico
| | - Angélica Ruiz-Ramírez
- Depto de Biomedicina Cardiovascular, Instituto Nacional de Cardiología Ignacio Chávez, Juan Badiano No 1, Colonia Sección XVI, Tlalpan, CP 14080, C.D. México, Mexico
| | - Héctor Quezada
- Laboratorio de Inmunología y Proteómica, Hospital Infantil de México Federico Gómez, Doctor Márquez # 162, Col. Doctores, CP 06720, C.D. México, Mexico
| | - Carlos L Céspedes Acuña
- Departamento de Ciencias Básicas, Facultad de Ciencias, Universidad del BioBio, Chillan, Chile
| | - Mohammed El-Hafidi
- Depto de Biomedicina Cardiovascular, Instituto Nacional de Cardiología Ignacio Chávez, Juan Badiano No 1, Colonia Sección XVI, Tlalpan, CP 14080, C.D. México, Mexico.
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8
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Stepnov AA, Forsberg Z, Sørlie M, Nguyen GS, Wentzel A, Røhr ÅK, Eijsink VGH. Unraveling the roles of the reductant and free copper ions in LPMO kinetics. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:28. [PMID: 33478537 PMCID: PMC7818938 DOI: 10.1186/s13068-021-01879-0] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Accepted: 01/07/2021] [Indexed: 05/02/2023]
Abstract
BACKGROUND Lytic polysaccharide monooxygenases (LPMOs) are monocopper enzymes that catalyze oxidative depolymerization of industrially relevant crystalline polysaccharides, such as cellulose, in a reaction that depends on an electron donor and O2 or H2O2. While it is well known that LPMOs can utilize a wide variety of electron donors, the variation in reported efficiencies of various LPMO-reductant combinations remains largely unexplained. RESULTS In this study, we describe a novel two-domain cellulose-active family AA10 LPMO from a marine actinomycete, which we have used to look more closely at the effects of the reductant and copper ions on the LPMO reaction. Our results show that ascorbate-driven LPMO reactions are extremely sensitive to very low amounts (micromolar concentrations) of free copper because reduction of free Cu(II) ions by ascorbic acid leads to formation of H2O2, which speeds up the LPMO reaction. In contrast, the use of gallic acid yields steady reactions that are almost insensitive to the presence of free copper ions. Various experiments, including dose-response studies with the enzyme, showed that under typically used reaction conditions, the rate of the reaction is limited by LPMO-independent formation of H2O2 resulting from oxidation of the reductant. CONCLUSION The strong impact of low amounts of free copper on LPMO reactions with ascorbic acid and O2, i.e. the most commonly used conditions when assessing LPMO activity, likely explains reported variations in LPMO rates. The observed differences between ascorbic acid and gallic acid show a way of making LPMO reactions less copper-dependent and illustrate that reductant effects on LPMO action need to be interpreted with great caution. In clean reactions, with minimized generation of H2O2, the (O2-driven) LPMO reaction is exceedingly slow, compared to the much faster peroxygenase reaction that occurs when adding H2O2.
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Affiliation(s)
- Anton A Stepnov
- Faculty of Chemistry, Biotechnology and Food Science, NMBU-Norwegian University of Life Sciences, Ås, Norway
| | - Zarah Forsberg
- Faculty of Chemistry, Biotechnology and Food Science, NMBU-Norwegian University of Life Sciences, Ås, Norway
| | - Morten Sørlie
- Faculty of Chemistry, Biotechnology and Food Science, NMBU-Norwegian University of Life Sciences, Ås, Norway
| | - Giang-Son Nguyen
- Department of Biotechnology and Nanomedicine, SINTEF Industry, Trondheim, Norway
| | - Alexander Wentzel
- Department of Biotechnology and Nanomedicine, SINTEF Industry, Trondheim, Norway
| | - Åsmund K Røhr
- Faculty of Chemistry, Biotechnology and Food Science, NMBU-Norwegian University of Life Sciences, Ås, Norway
| | - Vincent G H Eijsink
- Faculty of Chemistry, Biotechnology and Food Science, NMBU-Norwegian University of Life Sciences, Ås, Norway.
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9
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Kont R, Bissaro B, Eijsink VGH, Väljamäe P. Kinetic insights into the peroxygenase activity of cellulose-active lytic polysaccharide monooxygenases (LPMOs). Nat Commun 2020; 11:5786. [PMID: 33188177 PMCID: PMC7666214 DOI: 10.1038/s41467-020-19561-8] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 10/13/2020] [Indexed: 01/06/2023] Open
Abstract
Lytic polysaccharide monooxygenases (LPMOs) are widely distributed in Nature, where they catalyze the hydroxylation of glycosidic bonds in polysaccharides. Despite the importance of LPMOs in the global carbon cycle and in industrial biomass conversion, the catalytic properties of these monocopper enzymes remain enigmatic. Strikingly, there is a remarkable lack of kinetic data, likely due to a multitude of experimental challenges related to the insoluble nature of LPMO substrates, like cellulose and chitin, and to the occurrence of multiple side reactions. Here, we employed competition between well characterized reference enzymes and LPMOs for the H2O2 co-substrate to kinetically characterize LPMO-catalyzed cellulose oxidation. LPMOs of both bacterial and fungal origin showed high peroxygenase efficiencies, with kcat/KmH2O2 values in the order of 105-106 M-1 s-1. Besides providing crucial insight into the cellulolytic peroxygenase reaction, these results show that LPMOs belonging to multiple families and active on multiple substrates are true peroxygenases.
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Affiliation(s)
- Riin Kont
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
| | - Bastien Bissaro
- Faculty of Chemistry, Biotechnology and Food Science, NMBU-Norwegian University of Life Sciences, Ås, Norway.,INRAE, Aix Marseille University, UMR1163 Biodiversité et Biotechnologie Fongiques, 13009, Marseille, France
| | - Vincent G H Eijsink
- Faculty of Chemistry, Biotechnology and Food Science, NMBU-Norwegian University of Life Sciences, Ås, Norway
| | - Priit Väljamäe
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia.
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Saralkar P, Arsiwala T, Geldenhuys WJ. Nanoparticle formulation and in vitro efficacy testing of the mitoNEET ligand NL-1 for drug delivery in a brain endothelial model of ischemic reperfusion-injury. Int J Pharm 2020; 578:119090. [PMID: 32004683 PMCID: PMC7067674 DOI: 10.1016/j.ijpharm.2020.119090] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 01/22/2020] [Accepted: 01/27/2020] [Indexed: 12/12/2022]
Abstract
Ischemic reperfusion injury after a stroke is a leading cause of mortality and disability due to neuronal loss and tissue damage. Mitochondrial dysfunction plays a major role in the reperfusion-injury sequelae, and offers an attractive drug target. Mitochondrial derived reactive oxygen species (ROS) and resultant apoptotic cascade are among the primary mechanisms of neuronal death following ischemia and reperfusion injury. Here we optimized a nanoparticle formulation for the mitoNEET ligand NL-1, to target mitochondrial dysfunction post ischemic reperfusion (IR) injury. NL-1, a hydrophobic drug, was formulated using PLGA polymers with a particle size and entrapment efficiency of 123.9 ± 17.1 nm and 59.7 ± 10.1%, respectively. The formulation was characterized for physical state of NL-1, in vitro release, uptake and nanoparticle localization. A near complete uptake of nanoparticles was found to occur by three hours, with the process being energy-dependent and occurring via caveolar mediated endocytosis. The fluorescent nanoparticles were found to localize in the cytoplasm of the endothelial cells. An in vitro oxygen glucose deprivation (OGD) model to mimic IR was employed for in vitro efficacy testing in murine brain vascular endothelium cells (bEND.3 cells). Efficacy studies showed that both NL-1 and the nanoparticles loaded with NL-1 had a protective activity against peroxide generation, and displayed improved cellular viability, as seen via reduction in cellular apoptosis. Finally, PLGA nanoparticles were found to have a non-toxic profile in vitro, and were found to be safe for intravenous administration. This study lays the preliminary work for potential use of mitoNEET as a target and NL-1 as a therapeutic for the treatment of cerebral ischemia and reperfusion injury.
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Affiliation(s)
- Pushkar Saralkar
- Department of Pharmaceutical Sciences, West Virginia University School of Pharmacy, Morgantown, WV 26506, United States
| | - Tasneem Arsiwala
- Department of Pharmaceutical Sciences, West Virginia University School of Pharmacy, Morgantown, WV 26506, United States
| | - Werner J Geldenhuys
- Department of Pharmaceutical Sciences, West Virginia University School of Pharmacy, Morgantown, WV 26506, United States; Department of Neuroscience, West Virginia University, School of Medicine, Morgantown, WV 26506, United States.
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11
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Green-Sustainable Recovery of Phenolic and Antioxidant Compounds from Industrial Chestnut Shells Using Ultrasound-Assisted Extraction: Optimization and Evaluation of Biological Activities In Vitro. Antioxidants (Basel) 2020; 9:antiox9030267. [PMID: 32213812 PMCID: PMC7139998 DOI: 10.3390/antiox9030267] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 03/15/2020] [Accepted: 03/22/2020] [Indexed: 11/17/2022] Open
Abstract
Chestnut processing industry generates large amounts of by-products, including leaves, burs and shells that are a source of bioactive compounds. The purpose of this study was to establish an ultrasound-assisted extraction (UAE) of phenolic and antioxidant compounds from industrial chestnut shells. A central composite design (CCD) was conducted to analyze the effects of time (4–46 min) and temperature (34–76 °C) in the antioxidant activity (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing antioxidant power (FRAP)) and total phenolic compounds (TPC) of chestnut shells extracts. The optimal extraction conditions were obtained at 70 °C for 40 min. The optimal extract was characterized regarding phenolic profile, radical scavenging capacity, and effects on intestinal and dermal cell lines. The optimal extract revealed high amounts of ellagic acid (40.4 µg/mg dw), followed by caffeic acid derivative (15.4 µg/mg dw) and epigallocatechin (15.3 µg/mg dw). Indeed, the extract exhibited the highest scavenging efficiencies against NO● (IC50 = 0.1 µg/mL) and HOCl (IC50 = 0.7 µg/mL) and did not conducted to a decrease on HaCaT and HFF-1 viability up to 100 μg/mL. Oppositely, a decrease on Caco-2 and HT29-MTX viability was observed. This study suggests that UAE could be a sustainable option to valorize chestnut shells as raw material for different industries.
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12
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Chandra P, Enespa, Singh R. Soil Salinity and Its Alleviation Using Plant Growth–Promoting Fungi. Fungal Biol 2020. [DOI: 10.1007/978-3-030-48474-3_4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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13
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Alam MJ, Gupta R, Mahapatra NR, Goswami SK. Catestatin reverses the hypertrophic effects of norepinephrine in H9c2 cardiac myoblasts by modulating the adrenergic signaling. Mol Cell Biochem 2019; 464:205-219. [PMID: 31792650 DOI: 10.1007/s11010-019-03661-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 11/20/2019] [Indexed: 02/06/2023]
Abstract
Catestatin (CST) is a catecholamine release-inhibitory peptide secreted from the adrenergic neurons and the adrenal glands. It regulates the cardiovascular functions and it is associated with cardiovascular diseases. Though its mechanisms of actions are not known, there are evidences of cross-talk between the adrenergic and CST signaling. We hypothesized that CST moderates the adrenergic overdrive and studied its effects on norepinephrine-mediated hypertrophic responses in H9c2 cardiac myoblasts. CST alone regulated the expression of a number of fetal genes that are induced during hypertrophy. When cells were pre-treated CST, it blunted the modulation of those genes by norepinephrine. Norepinephrine (2 µM) treatment also increased cell size and enhanced the level of Troponin T in the sarcomere. These effects were attenuated by the treatment with CST. CST attenuated the immediate generation of ROS and the increase in glutathione peroxidase activity induced by norepinephrine treatment. Expression of fosB and AP-1 promoter-reporter constructs was used as the endpoint readout for the interaction between the CST and adrenergic signals at the gene level. It showed that CST largely attenuates the stimulatory effects of norepinephrine and other mitogenic signals through the modulation of the gene regulatory modules in a characteristic manner. Depending upon the dose, the signaling by CST appears to be disparate, and at 10-25 nM doses, it primarily moderated the signaling by the β1/2-adrenoceptors. This study, for the first time, provides insights into the modulation of adrenergic signaling in the heart by CST.
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Affiliation(s)
- Md Jahangir Alam
- Translational Health Science and Technology Institute, NCR Biotech Science Cluster, Fridabad, 121001, India
| | - Richa Gupta
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Nitish R Mahapatra
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, 600036, India
| | - Shyamal K Goswami
- Translational Health Science and Technology Institute, NCR Biotech Science Cluster, Fridabad, 121001, India.
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14
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Zhu D, Zuo J, Tan L, Pang H, Ma H. Enzymeless electrochemical determination of hydrogen peroxide at a heteropolyanion-based composite film electrode. NEW J CHEM 2019. [DOI: 10.1039/c8nj04570d] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
For the first time, a sensitive and efficient composite film of [PB/WV–Pt@Pd]6was constructed for H2O2detection.
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Affiliation(s)
- Di Zhu
- School of Materials Science and Engineering
- College of Chemical and Environmental Engineering
- Harbin University of Science and Technology
- Harbin 150040
- China
| | - Jingwei Zuo
- School of Materials Science and Engineering
- College of Chemical and Environmental Engineering
- Harbin University of Science and Technology
- Harbin 150040
- China
| | - Lichao Tan
- School of Materials Science and Engineering
- College of Chemical and Environmental Engineering
- Harbin University of Science and Technology
- Harbin 150040
- China
| | - Haijun Pang
- School of Materials Science and Engineering
- College of Chemical and Environmental Engineering
- Harbin University of Science and Technology
- Harbin 150040
- China
| | - Huiyuan Ma
- School of Materials Science and Engineering
- College of Chemical and Environmental Engineering
- Harbin University of Science and Technology
- Harbin 150040
- China
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15
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Mitra S, Prasad P, Chakraborty S. A Unified View of Assessing the Pro-oxidant versus Antioxidant Nature of Amyloid Beta Conformers. Chembiochem 2018; 19:2360-2371. [PMID: 30151968 DOI: 10.1002/cbic.201800446] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Indexed: 11/06/2022]
Abstract
Transition-metal-catalyzed oxidative stress is a widespread concern in the pathogenesis of Alzheimer's disease. However, the exact role of amyloid beta oligomers towards oxidative stress is widely debated. Assessing the oxidative nature of the oligomers in vitro is complicated by the different experimental conditions under which they are prepared. We have investigated Cu2+ -catalyzed reactive oxygen species (ROS) generation by using oligomers prepared in phosphate-buffered saline (AβO-PBS ) and in cell culture medium (AβO-CCM ), and compared their activities with respect to the monomers and fibrils prepared at neutral and acidic pH. Although both are deca- to dodecamers, the AβO-PBS oligomers have a spherical morphology and are smaller than the AβO-CCM . The AβO-PBS behaved as pro-oxidants; in contrast, AβO-CCM quench OH. generation attributed to CCM itself. Although the pro-oxidant oligomers showed oxidation, they also partially protect themselves from radical damage and maintain their overall spherical arrangement. The monomers and fibrils manifested antioxidant properties: radical scavenging as opposed to redox silencing. A dual role of Aβ species depending on the stage of the disease is proposed. In the earlier stages, the monomers can act as antioxidants, whereas at the later stages, the oligomers take on a pro-oxidant role. Kaempferol, a natural flavonoid, bound Cu2+ in 2:1 ratio and abolished ROS production in all Aβ species. It also distinctly modified the folding landscape of Aβ species into new or altered morphologies.
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Affiliation(s)
- Suchitra Mitra
- Department of Chemistry and Biochemistry, University of Mississippi, 305 Coulter Hall, University, MS, 38677, USA
| | - Pallavi Prasad
- Department of Chemistry and Biochemistry, University of Mississippi, 305 Coulter Hall, University, MS, 38677, USA
| | - Saumen Chakraborty
- Department of Chemistry and Biochemistry, University of Mississippi, 305 Coulter Hall, University, MS, 38677, USA
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Audi SH, Friedly N, Dash RK, Beyer AM, Clough AV, Jacobs ER. Detection of hydrogen peroxide production in the isolated rat lung using Amplex red. Free Radic Res 2018; 52:1052-1062. [PMID: 30175632 DOI: 10.1080/10715762.2018.1511051] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The objectives of this study were to develop a robust protocol to measure the rate of hydrogen peroxide (H2O2) production in isolated perfused rat lungs, as an index of oxidative stress, and to determine the cellular sources of the measured H2O2 using the extracellular probe Amplex red (AR). AR was added to the recirculating perfusate in an isolated perfused rat lung. AR's highly fluorescent oxidation product resorufin was measured in the perfusate. Experiments were carried out without and with rotenone (complex I inhibitor), thenoyltrifluoroacetone (complex II inhibitor), antimycin A (complex III inhibitor), potassium cyanide (complex IV inhibitor), or diohenylene iodonium (inhibitor of flavin-containing enzymes, e.g. NAD(P)H oxidase or NOX) added to the perfusate. We also evaluated the effect of acute changes in oxygen (O2) concentration of ventilation gas on lung rate of H2O2 release into the perfusate. Baseline lung rate of H2O2 release was 8.45 ± 0.31 (SEM) nmol/min/g dry wt. Inhibiting mitochondrial complex II reduced this rate by 76%, and inhibiting flavin-containing enzymes reduced it by another 23%. Inhibiting complex I had a small (13%) effect on the rate, whereas inhibiting complex III had no effect. Inhibiting complex IV increased this rate by 310%. Increasing %O2 in the ventilation gas mixture from 15 to 95% had a small (27%) effect on this rate, and this O2-dependent increase was mostly nonmitochondrial. Results suggest complex II as a potentially important source and/or regulator of mitochondrial H2O2, and that most of acute hyperoxia-enhanced lung rate of H2O2 release is from nonmitochondrial rather than mitochondrial sources.
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Affiliation(s)
- Said H Audi
- a Medical College of Wisconsin Department of Biomedical Engineering , Marquette University , Milwaukee , WI , USA.,c Division of Pulmonary and Critical Care Medicine , Medical College of Wisconsin , Milwaukee, WI , USA
| | - Nina Friedly
- a Medical College of Wisconsin Department of Biomedical Engineering , Marquette University , Milwaukee , WI , USA
| | - Ranjan K Dash
- a Medical College of Wisconsin Department of Biomedical Engineering , Marquette University , Milwaukee , WI , USA
| | - Andreas M Beyer
- d Department of Medicine , Medical College of Wisconsin , Milwaukee, WI , USA
| | - Anne V Clough
- e Department of Mathematics, Statistics, and Computer Science , Marquette University , Milwaukee , WI , USA
| | - Elizabeth R Jacobs
- b Zablocki VA Medical Center , Milwaukee, WI , USA.,c Division of Pulmonary and Critical Care Medicine , Medical College of Wisconsin , Milwaukee, WI , USA
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17
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Nisimoto Y, Ogawa H, Kadokawa Y, Qiao S. NADPH oxidase 4 function as a hydrogen peroxide sensor. J Biochem 2018; 163:489-501. [PMID: 29365138 DOI: 10.1093/jb/mvy014] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 12/24/2017] [Indexed: 11/13/2022] Open
Abstract
Nox4, a member of the NADPH- and oxygen-dependent oxidoreductases that generate reactive oxygen species (ROS), is widely expressed and constitutively active. To understand better its function and regulation, specific mutations in the Nox4 dehydrogenase (DH) domain were examined for effects on Nox4 oxidase activity. Transfection of His6-tagged Nox4 increased the amount of p22phox subunit in HEK293 cells, and a higher level of the heterodimer was observed in the nucleus-enriched fraction (NEF). NEF from Nox4-expressing HEK293 cells exhibited oxygen and H2O2 concentration-dependent NADPH oxidation rate. In Nox4-expressing cells, NEF and its partially purified form, the Nox4(P437H) mutant almost completely lost its oxidase activity, while Nox4(C546S), Nox4(C546L) or/and (C547L) had a significantly decreased rate of ROS production. The NADPH-dependent reduction of cytochrome c or cytochrome b5 by purified Nox4 DH domain was found regulated by the H2O2 concentration, and C546L and C547L mutants showed lower rates of the hemeprotein reduction. These conserved Cys residues in the DH domain respond to the cytosolic H2O2 concentration to regulate Nox4 activity.
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Affiliation(s)
- Yukio Nisimoto
- Department of Biomedical Science, College of Life and Health Science, Chubu University, 1200 Matsumoto-cho, Kasugai, Aichi 487-8501, Japan
| | - Hisamitsu Ogawa
- Department of Biology, School of Medicine, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Yuzo Kadokawa
- Department of Biology, School of Medicine, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Shanlou Qiao
- Department of Biomedical Science, College of Life and Health Science, Chubu University, 1200 Matsumoto-cho, Kasugai, Aichi 487-8501, Japan
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Motaghed Mazhabi R, Ge L, Jiang H, Wang X. A facile photoelectrochemical sensor for high sensitive ROS and AA detection based on graphitic carbon nitride nanosheets. Biosens Bioelectron 2018; 107:54-61. [DOI: 10.1016/j.bios.2018.02.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 01/31/2018] [Accepted: 02/01/2018] [Indexed: 12/21/2022]
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Jiang S, Penner MH. Overcoming Reductant Interference in Peroxidase-Based Assays for Hydrogen Peroxide Quantification. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2017; 65:8213-8219. [PMID: 28805389 DOI: 10.1021/acs.jafc.7b02248] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
A problem commonly encountered when using peroxidase-based methods for hydrogen peroxide quantification in biobased matrixes is interference due to the presence of endogenous reductants. Such assays are typically based on the generation of an oxidized reporter molecule in direct proportion to the amount of hydrogen peroxide reduced in the peroxidase-catalyzed reaction. Endogenous reductants confound such assays by reducing the oxidized reporter molecule, thus resulting in underestimates of hydrogen peroxide content. In the present work, we demonstrate how this problem can be circumvented by selectively oxidizing offending compounds by treatment with the oxidized reporter molecule prior to initiating the peroxidase reaction for hydrogen peroxide quantification. The approach is demonstrated using horseradish peroxidase, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), as the reporter molecule and a representative garlic paste as the hydrogen peroxide-containing biobased matrix. The approach is expected to be generally applicable to a wide range of peroxidase-based assays when applied to complex biobased systems.
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Affiliation(s)
- Shu Jiang
- Department of Food Science and Technology, Oregon State University , Corvallis, Oregon 97331-6602, United States
| | - Michael H Penner
- Department of Food Science and Technology, Oregon State University , Corvallis, Oregon 97331-6602, United States
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20
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A novel fluorimetric method for laccase activities measurement using Amplex Red as substrate. Talanta 2016; 162:143-150. [PMID: 27837810 DOI: 10.1016/j.talanta.2016.10.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 09/18/2016] [Accepted: 10/02/2016] [Indexed: 11/21/2022]
Abstract
In this paper, a novel fluorescence-based method for laccase assay was presented. The method was based on the transformation of Amplex Red into a highly fluorescent and colored resorufin catalyzed by laccase in the presence of O2. The catalysis and transformation mechanism were investigated in detail. The kinetic parameters of the Amplex Red catalysis by laccase were determined using the Lineweaver-Burk equation. Vmax and Km were estimated to be 15.63μmolmin-1 and 76.88μmolL-1, respectively. Under optimal conditions, a good linear correlation was found between fluorescence intensity and laccase activities within 5.62-702UL-1 (r=0.9992), with a detection limit of 1.76UL-1 (S/N=3). A series of repeatability measurements (351UL-1 laccase) gave reproducible results with a relative standard deviation (RSD) of 1.9% (n=11). The recoveries ranged from 93.7% to 100.0% after standard additions. Common existing species such as Mg2+, Zn2+, Ni2+, Al3+, Co2+, Cd2+, K+, Ca2+, Na+, Fe3+, Li+, Cu2+, Mn2+, Fe2+, l-lysine, glycine, glucose, phenol, humic acid, lignin peroxidase, manganese peroxidase alkaline phosphatase, cellulose, glucose oxidase, urease, catalase, invertase, and horseradish peroxidase did not significantly exhibit interference. The test solution (i.e., Amplex Red stock solution) could stabilize at least three months via storage in dark at 4±0.1°C. These results confirmed that the laccase-Amplex Red system was stable and reproducible with strong anti-interference ability and good selectivity, suggesting that this method can has great potential in practical applications for the assay of laccase activity. The proposed method was further successfully used to detect laccase activities in 38 soil samples. We noticed that the laccase activity significantly correlated with total nitrogen content (r=0.559; p<0.01) of soil, indicating laccase activity assay holds great promise as an index of soil analysis. These findings indicate that this presented method has great perspective in ecological investigation and fundamental research of soil environment.
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21
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Shi L, Wang Y, Ito F, Okazaki Y, Tanaka H, Mizuno M, Hori M, Richardson DR, Toyokuni S. Biphasic effects of l-ascorbate on the tumoricidal activity of non-thermal plasma against malignant mesothelioma cells. Arch Biochem Biophys 2016; 605:109-16. [DOI: 10.1016/j.abb.2016.05.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 05/02/2016] [Accepted: 05/20/2016] [Indexed: 12/22/2022]
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22
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Oliveri V, Bellia F, Pietropaolo A, Vecchio G. Unusual Cyclodextrin Derivatives as a New Avenue to Modulate Self- and Metal-Induced Aβ Aggregation. Chemistry 2015; 21:14047-59. [PMID: 26298549 DOI: 10.1002/chem.201502155] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Indexed: 12/19/2022]
Abstract
Mounting evidence suggests an important role of cyclodextrins in providing protection in neurodegenerative disorders. Metal dyshomeostasis is reported to be a pathogenic factor in neurodegeneration because it could be responsible for damage involving oxidative stress and protein aggregation. As such, metal ions represent an effective target. To improve the metal-binding ability of cyclodextrin, we synthesized three new 8-hydroxyquinoline-cyclodextrin conjugates with difunctionalized cyclodextrins. In particular, the 3-difunctionalized regioisomer represents the first example of cyclodextrin with two pendants at the secondary rim, resulting in a promising compound. The derivatives have significant antioxidant capacity and the powerful activity in inhibiting self-induced amyloid-β aggregation seems to be led by synergistic effects of both cyclodextrin and hydroxyquinoline. Moreover, the derivatives are also able to complex metal ions and to inhibit metal-induced protein aggregation. Therefore, these compounds could have potential as therapeutic agents in diseases related to protein aggregation and metal dyshomeostasis.
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Affiliation(s)
- Valentina Oliveri
- Dipartimento di Scienze Chimiche, Università di Catania, Viale A. Doria 6, 95125, Catania (Italy).,Consorzio Interuniversitario di Ricerca in Chimica dei Metalli nei Sistemi Biologici, C.I.R.C.M.S.B, Unità di Ricerca di Catania, 95125 Catania (Italy)
| | - Francesco Bellia
- Istituto di Biostrutture e Bioimmagini, CNR, Via P. Gaifami 18, 95126 Catania, Italy
| | - Adriana Pietropaolo
- Dipartimento di Scienze della Salute, Università di Catanzaro, Viale Europa, 88100 Catanzaro, Italy
| | - Graziella Vecchio
- Dipartimento di Scienze Chimiche, Università di Catania, Viale A. Doria 6, 95125, Catania (Italy).
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Li H, Li L, Wang X, Li Q, Du M, Tang B. Dual-calibration coefficient: a more accurate protocol for simultaneous determination of superoxide and hydrogen peroxide in human HepG2 cell extracts. Sci China Chem 2015. [DOI: 10.1007/s11426-015-5396-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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24
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Abstract
Nox4 is an oddity among members of the Nox family of NADPH oxidases [seven isoenzymes that generate reactive oxygen species (ROS) from molecular oxygen] in that it is constitutively active. All other Nox enzymes except for Nox4 require upstream activators, either calcium or organizer/activator subunits (p47(phox), NOXO1/p67(phox), and NOXA1). Nox4 may also be unusual as it reportedly releases hydrogen peroxide (H₂O₂) in contrast to Nox1-Nox3 and Nox5, which release superoxide, although this result is controversial in part because of possible membrane compartmentalization of superoxide, which may prevent detection. Our studies were undertaken (1) to identify the Nox4 ROS product using a membrane-free, partially purified preparation of Nox4 and (2) to test the hypothesis that Nox4 activity is acutely regulated not by activator proteins or calcium, but by cellular pO₂, allowing it to function as an O₂ sensor, the output of which is signaling H₂O₂. We find that approximately 90% of the electron flux through isolated Nox4 produces H₂O₂ and 10% forms superoxide. The kinetic mechanism of H₂O₂ formation is consistent with a mechanism involving binding of one oxygen molecule, which is then sequentially reduced by the heme in two one-electron reduction steps first to form a bound superoxide intermediate and then H₂O₂; kinetics are not consistent with a previously proposed internal superoxide dismutation mechanism involving two oxygen binding/reduction steps for each H₂O₂ formed. Critically, Nox4 has an unusually high Km for oxygen (∼18%), similar to the values of known oxygen-sensing enzymes, compared with a Km of 2-3% for Nox2, the phagocyte NADPH oxidase. This allows Nox4 to generate H₂O₂ as a function of oxygen concentration throughout a physiological range of pO2 values and to respond rapidly to changes in pO₂.
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25
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Hsu KI, Lien CW, Lin CH, Chang HT, Huang CC. Immobilization of iron hydroxide/oxide on reduced graphene oxide: peroxidase-like activity and selective detection of sulfide ions. RSC Adv 2014. [DOI: 10.1039/c4ra05047a] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
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26
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Condezo-Hoyos L, Mohanty IP, Noratto GD. Technical note: Optimization of lactose quantification based on coupled enzymatic reactions. J Dairy Sci 2014; 97:2066-70. [DOI: 10.3168/jds.2013-7436] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Accepted: 01/01/2014] [Indexed: 12/25/2022]
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27
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Liochev SI. Free radicals: how do we stand them? Anaerobic and aerobic free radical (chain) reactions involved in the use of fluorogenic probes and in biological systems. Med Princ Pract 2014; 23:195-203. [PMID: 24356000 PMCID: PMC5586870 DOI: 10.1159/000357120] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Accepted: 11/07/2013] [Indexed: 01/21/2023] Open
Abstract
Biologically significant conclusions have been based on the use of fluorogenic and luminogenic probes for the detection of reactive species. The basic mechanisms of the processes involved have not been satisfactorily elucidated. In the present work, the mechanism of the enzyme and photosensitized oxidation of NAD(P)H by resorufin is analyzed and appears to involve both aerobic and anaerobic free radical chain reactions. There are two major fallouts of this analysis. Many of the conclusions about the participation of radicals based on the use of probes such as resorufin and Amplex red need reevaluation. It is also concluded that anaerobic free radical reactions may be biologically significant, and the possible existence of enzymatic systems to eliminate certain free radicals is discussed.
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Leong SL, Young TR, Barnham KJ, Wedd AG, Hinds MG, Xiao Z, Cappai R. Quantification of copper binding to amyloid precursor protein domain 2 and its Caenorhabditis elegans ortholog. Implications for biological function. Metallomics 2014; 6:105-16. [DOI: 10.1039/c3mt00258f] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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29
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Young TR, Kirchner A, Wedd AG, Xiao Z. An integrated study of the affinities of the Aβ16 peptide for Cu(i) and Cu(ii): implications for the catalytic production of reactive oxygen species. Metallomics 2014; 6:505-17. [DOI: 10.1039/c4mt00001c] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Affinities of Aβ16 peptide and several selected variants for Cu(i) and Cu(ii) were determined with new probes and correlated to their binding modes and abilities in promoting ROS generation.
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Affiliation(s)
- Tessa R. Young
- The Bio21 Molecular Science and Biotechnology Institute
- The University of Melbourne
- Victoria 3010, Australia
- School of Chemistry
- The University of Melbourne
| | - Angie Kirchner
- The Bio21 Molecular Science and Biotechnology Institute
- The University of Melbourne
- Victoria 3010, Australia
- School of Chemistry
- The University of Melbourne
| | - Anthony G. Wedd
- The Bio21 Molecular Science and Biotechnology Institute
- The University of Melbourne
- Victoria 3010, Australia
- School of Chemistry
- The University of Melbourne
| | - Zhiguang Xiao
- The Bio21 Molecular Science and Biotechnology Institute
- The University of Melbourne
- Victoria 3010, Australia
- School of Chemistry
- The University of Melbourne
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Zhang X, Soldati T. Detecting, visualizing and quantitating the generation of reactive oxygen species in an amoeba model system. J Vis Exp 2013:e50717. [PMID: 24300479 PMCID: PMC3970549 DOI: 10.3791/50717] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Reactive oxygen species (ROS) comprise a range of reactive and short-lived, oxygen-containing molecules, which are dynamically interconverted or eliminated either catalytically or spontaneously. Due to the short life spans of most ROS and the diversity of their sources and subcellular localizations, a complete picture can be obtained only by careful measurements using a combination of protocols. Here, we present a set of three different protocols using OxyBurst Green (OBG)-coated beads, or dihydroethidium (DHE) and Amplex UltraRed (AUR), to monitor qualitatively and quantitatively various ROS in professional phagocytes such as Dictyostelium. We optimised the beads coating procedures and used OBG-coated beads and live microscopy to dynamically visualize intraphagosomal ROS generation at the single cell level. We identified lipopolysaccharide (LPS) from E. coli as a potent stimulator for ROS generation in Dictyostelium. In addition, we developed real time, medium-throughput assays using DHE and AUR to quantitatively measure intracellular superoxide and extracellular H2O2 production, respectively.
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Affiliation(s)
- Xuezhi Zhang
- Department of Biochemistry, University of Geneva
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31
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Murzaeva SV, Belova SP, Mironova GD. Determination of the antioxidant properties of activators of mitochondrial ATP-dependent potassium channels with the Amplex Red fluorescent indicator. APPL BIOCHEM MICRO+ 2013. [DOI: 10.1134/s0003683813040108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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32
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Ehrl BN, Liebherr RB, Gorris HH. Single molecule kinetics of horseradish peroxidase exposed in large arrays of femtoliter-sized fused silica chambers. Analyst 2013; 138:4260-5. [PMID: 23752650 DOI: 10.1039/c3an00809f] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Large arrays of femtoliter-sized chambers were etched into the surface of fused silica slides to enclose and observe hundreds of single horseradish peroxidase (HRP) molecules in parallel. Individual molecules of HRP oxidize the fluorogenic substrate Amplex Red to fluorescent resorufin in separate chambers, which was monitored by fluorescence microscopy. Photooxidation of Amplex Red and photobleaching of resorufin have previously limited the analysis of HRP in femtoliter arrays. We have strongly reduced these effects by optimizing the fluorescence excitation and detection scheme to yield accurate single molecule substrate turnover rates. We demonstrate the presence of long-lived kinetic states of single HRP molecules that are individually different for each molecule in the array. The large number of molecules investigated in parallel provides excellent statistics on the activity distribution in the enzyme population, which is similar to that reported for other enzymes such as β-galactosidase. We have further confirmed that the product formation of HRP in femtoliter chambers is 10-fold lower than that in the bulk solution due to the particular two-step redox reaction mechanism of HRP.
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Affiliation(s)
- Benno N Ehrl
- Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, D-93040 Regensburg, Germany
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Li H, Hao W, Hu J, Wu H. A photoelectrochemical sensor based on nickel hydroxyl-oxide modified n-silicon electrode for hydrogen peroxide detection in an alkaline solution. Biosens Bioelectron 2013; 47:225-30. [PMID: 23584227 DOI: 10.1016/j.bios.2013.03.028] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 02/27/2013] [Accepted: 03/12/2013] [Indexed: 11/17/2022]
Abstract
A novel photoelectrochemical hydrogen peroxide (H2O2) sensor was constructed with platinum (Pt) and nickel hydroxyl-oxide (NiOOH) double layers modified n-silicon electrode (NiOOH/Pt/n-n(+)-Si). About 40nm Pt layer and about 100nm Ni layer were successively coated on the front surface of n-n(+)-Si (111) wafers by vacuum evaporating. A stable layer of NiOOH was formed through oxidation of the Ni layer on the coated silicon wafer by the electrochemical method. The surface of modified electrode was characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The NiOOH/Pt/n-n(+)-Si electrode has been used for determination of H2O2 with a two-electrode cell in the absence of reference electrode by photocurrent measurement at a zero bias. The photoelectrochemical sensor showed a good linear response to H2O2 concentrations in a range from 1.0×10(-5) to 6×10(-5)M with a determination limit (S/N=3) of 2.2μM. The NiOOH/Pt/n-n(+)-Si electrode exhibited excellent reproducibility and stability. Particularly, the facile measurement requirements made this novel modified electrode promising for the development of outdoor H2O2 sensors.
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Affiliation(s)
- Huaixiang Li
- College of Chemistry, Chemical Engineering and Materials Science, Shandong Provincial Key Laboratory of Clean Production of Fine Chemicals, Shandong Normal University, Jinan 250014, PR China.
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Alies B, Sasaki I, Proux O, Sayen S, Guillon E, Faller P, Hureau C. Zn impacts Cu coordination to amyloid-β, the Alzheimer's peptide, but not the ROS production and the associated cell toxicity. Chem Commun (Camb) 2013; 49:1214-6. [PMID: 23282470 DOI: 10.1039/c2cc38236a] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Combined coordination of Zn(II) and Cu(I) or Cu(II) to the amyloid-β peptide has been investigated using XANES, EPR and NMR spectroscopies. While Zn(II) does alter Cu(II) binding to Aβ, this has no effect on (Aβ)Cu induced ROS production and associated cell toxicity.
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Affiliation(s)
- Bruno Alies
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205, route de Narbonne, F-31077 Toulouse, France
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Zhao B, Summers FA, Mason RP. Photooxidation of Amplex Red to resorufin: implications of exposing the Amplex Red assay to light. Free Radic Biol Med 2012; 53:1080-7. [PMID: 22765927 PMCID: PMC3501008 DOI: 10.1016/j.freeradbiomed.2012.06.034] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Revised: 06/21/2012] [Accepted: 06/25/2012] [Indexed: 10/28/2022]
Abstract
The Amplex Red assay, a fluorescent assay for the detection of H(2)O(2), relies on the reaction of H(2)O(2) and colorless, nonfluorescent Amplex Red with a 1:1 stoichiometry to form colored, fluorescent resorufin, catalyzed by horseradish peroxidase (HRP). We have found that resorufin is artifactually formed when Amplex Red is exposed to light. In the absence of H(2)O(2) and HRP, the absorption and fluorescence spectra of Amplex Red changed during exposure to ambient room light or instrumental excitation light, clearly indicating that the fluorescent product resorufin had formed. This photochemistry was initiated by trace amounts of resorufin that are present in Amplex Red stock solutions. ESR spin-trapping studies demonstrated that superoxide radical was an intermediate in this process. Oxygen consumption measurements further confirmed that superoxide and H(2)O(2) were artifactually produced by the photooxidation of Amplex Red. The artifactual formation of resorufin was also significantly increased by the presence of superoxide dismutase or HRP. This photooxidation process will result in a less sensitive assay for H(2)O(2) under ambient light exposure and potentially invalid measurements under high energy exposure such as UVA irradiation. In general, precautions should be taken to minimize exposure to light during measurement of oxidative stress with Amplex Red.
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Affiliation(s)
| | - Fiona A. Summers
- To whom correspondence should be addressed: Laboratory of Toxicology and Pharmacology, NIEHS/NIH, Research Triangle Park, NC 27709, USA. Fax: +1-919-541-1043; (F.A. Summers)
| | - Ronald P. Mason
- Laboratory of Toxicology and Pharmacology, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC 27709
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Rodrigues JV, Gomes CM. Mechanism of superoxide and hydrogen peroxide generation by human electron-transfer flavoprotein and pathological variants. Free Radic Biol Med 2012; 53:12-9. [PMID: 22588007 DOI: 10.1016/j.freeradbiomed.2012.04.016] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 04/10/2012] [Accepted: 04/12/2012] [Indexed: 11/26/2022]
Abstract
Reactive oxygen species production by mitochondrial enzymes plays a fundamental role both in cellular signaling and in the progression of dysfunctional states. However, sources of reactive oxygen species and the mechanisms by which enzymes produce these reactive species still remain elusive. We characterized the generation of reactive oxygen species by purified human electron-transfer flavoprotein (ETF), a mitochondrial enzyme that has a central role in the metabolism of lipids, amino acids, and choline. The results showed that ETF produces significant amounts of both superoxide and hydrogen peroxide in the presence of its partner enzyme medium-chain acyl-CoA dehydrogenase (MCAD). ETF-mediated production of reactive oxygen species is partially inhibited at high MCAD/ETF ratios, whereas it is enhanced at high ionic strength. Determination of the reduction potentials of ETF showed that thermodynamic properties of the FAD cofactor are changed upon formation of a complex between ETF and MCAD, supporting the notion that protein:protein interactions modulate the reactivity of the protein with dioxygen. Two pathogenic ETF variants were also studied to determine which factors modulate the reactivity toward molecular oxygen and promote reactive oxygen species production. The results obtained show that destabilized conformations and defective protein:protein interactions increase the ability of ETF to generate reactive oxygen species. A possible role for these processes in mitochondrial dysfunction in metabolic disorders of fatty acid β-oxidation is discussed.
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Affiliation(s)
- João V Rodrigues
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, 2780-157 Oeiras, Portugal
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Nadithe V, Mishra D, Bae YH. Poly(ethylene glycol) cross-linked hemoglobin with antioxidant enzymes protects pancreatic islets from hypoxic and free radical stress and extends islet functionality. Biotechnol Bioeng 2012; 109:2392-401. [PMID: 22447333 DOI: 10.1002/bit.24501] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Revised: 03/12/2012] [Accepted: 03/15/2012] [Indexed: 02/07/2023]
Abstract
The objective of this study was to investigate the efficiency of multifunctional poly(ethylene glycol)-based hemoglobin conjugates crosslinked with antioxidant enzymes for their ability to protect an oxygen carrier (hemoglobin) and insulin secreting islets from the combination of hypoxic and free radical stress under simulated transplantation conditions. In this study, RINm5F cells and isolated pancreatic islets were challenged with oxidants (H(2)O(2) or xanthine and xanthine oxidase) and incubated with conjugates (hemoglobin-hemoglobin or superoxide dismutase-catalase-hemoglobin) in normoxia (21% oxygen) or hypoxia (6% or 1% oxygen). Hemoglobin protection, intracellular free radical activity and cell viability in RINm5F cells measured by methemoglobin, dichlorofluorescein-diacetate, and (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay, respectively, showed that cells were better protected by conjugates containing antioxidant enzymes. Insulin secretion from islets and qualitative confocal evaluation of viability showed beta cells were protected by conjugates containing antioxidant enzymes when exposed to induced stress. Our study suggested that antioxidant enzymes play a significant role in hemoglobin protection and thus extended cell protection.
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Affiliation(s)
- Venkatareddy Nadithe
- Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, Salt Lake City, Utah 84108, USA
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Faúndez M, Rojas M, Bohle P, Reyes C, Letelier ME, Aliaga ME, Speisky H, Lissi E, López-Alarcón C. Pyrogallol red oxidation induced by superoxide radicals: application to evaluate redox cycling of nitro compounds. Anal Biochem 2011; 419:284-91. [PMID: 21945352 DOI: 10.1016/j.ab.2011.08.048] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 08/25/2011] [Accepted: 08/27/2011] [Indexed: 11/30/2022]
Abstract
The bleaching of the pyrogallol red (PGR) dye mediated by superoxide anion radicals (O(2)(-)) generated from the xanthine/xanthine oxidase system (X/XO) was studied by UV-visible spectrophotometry. The absorption band (at 540 nm) of PGR quickly decreased in the presence of X/XO, implying an efficient reaction of O(2)(-) with PGR. The process was unaffected by catalase (CAT), but completely abolished by superoxide dismutase (SOD). A mechanism of the reaction involving the consumption of one PGR molecule by two O(2)(-) to generate one molecule of H(2)O(2) is proposed. PGR was used as a probe to estimate the rate of O(2)(-) generation in redox cycling reactions of a series of nitro compounds mediated by rat liver microsomes. The consumption of PGR induced by the redox cycling of nitrofurantoin was totally eliminated by the addition of SOD but unaffected by CAT. The initial rate of consumption of PGR mediated by the redox cycling of others nitro derivatives follows the order: furazolidindione > nitrofurantoin > nifurtimox > benznidazole > chloramphenicol. We concluded that PGR can be used as a probe to estimate the release of O(2)(-) from enzymatic systems or from the redox cycling of nitro compounds.
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Affiliation(s)
- M Faúndez
- Departamento de Farmacia, Facultad de Química, Pontificia Universidad Católica de Chile, CP 782 0436, Santiago, Chile
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