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Ebea PO, Vidyasagar S, Connor JR, Frazer DM, Knutson MD, Collins JF. Oral iron therapy: Current concepts and future prospects for improving efficacy and outcomes. Br J Haematol 2024; 204:759-773. [PMID: 38253961 PMCID: PMC10939879 DOI: 10.1111/bjh.19268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 12/01/2023] [Accepted: 12/08/2023] [Indexed: 01/24/2024]
Abstract
Iron deficiency (ID) and iron-deficiency anaemia (IDA) are global public health concerns, most commonly afflicting children, pregnant women and women of childbearing age. Pathological outcomes of ID include delayed cognitive development in children, adverse pregnancy outcomes and decreased work capacity in adults. IDA is usually treated by oral iron supplementation, typically using iron salts (e.g. FeSO4 ); however, dosing at several-fold above the RDA may be required due to less efficient absorption. Excess enteral iron causes adverse gastrointestinal side effects, thus reducing compliance, and negatively impacts the gut microbiome. Recent research has sought to identify new iron formulations with better absorption so that lower effective dosing can be utilized. This article outlines emerging research on oral iron supplementation and focuses on molecular mechanisms by which different supplemental forms of iron are transported across the intestinal epithelium and whether these transport pathways are subject to regulation by the iron-regulatory hormone hepcidin.
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Affiliation(s)
- Pearl O. Ebea
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, USA
| | | | - James R. Connor
- Department of Neurosurgery, Penn State College of Medicine, Hershey, PA, USA
| | - David M. Frazer
- Molecular Nutrition Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Mitchell D. Knutson
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, USA
| | - James F. Collins
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, USA
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2
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Arita A, Kita I, Shinoda S. Internalization and Decrease of Duodenal DMT1 Involved in Transient Suppression of Iron Uptake in Short-Acting Mucosal Block. Biol Trace Elem Res 2022; 200:4795-4806. [PMID: 34997531 DOI: 10.1007/s12011-021-03053-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 11/27/2021] [Indexed: 12/30/2022]
Abstract
Mucosal block (MB) is induced by the oral administration of excess iron (10 mg) and suppresses intestinal iron absorption for 3-72 h. The inhibition of iron absorption is accompanied by the downregulation of molecules associated with intestinal iron absorption. Recently, we found that a smaller amount of iron (1 mg) also induced a transient suppression of iron uptake without affecting gene expression levels (short-acting mucosal block, SAMB), which is specific to iron-deficient rats. In this study, we investigated how the nonheme iron transporters divalent metal transporter 1 (DMT1) and ferroportin (FPN) are involved in the transient suppression of iron uptake in SAMB. To induce SAMB, a test solution containing 1 mg iron was infused into the duodenum loop in iron-sufficient and iron-deficient rats. Total duodenal DMT1 and DMT1-IRE expression were increased during iron deficiency. After 15 min of 1 mg iron loading, the fluorescence intensity of duodenal DMT1 in iron-deficient rats was decreased and was comparable to that in iron-sufficient rats. Internalized DMT1-IRE as puncta was observed at 15 and 60 min after 1 mg iron loading, and the number of punctas was significantly increased after 60 min compared with control. There was no effect of 1 mg iron loading on the intracellular distribution of duodenal FPN. Our results suggest that the decrease and internalization of DMT1-IRE protein may be related, at least in part, to iron uptake suppression in SAMB.
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Affiliation(s)
- Anna Arita
- Department of Health Promotion Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University, Hachioji, Tokyo, Japan.
- Institute of Food, Nutrition, and Health, Jumonji University, Niiza, Saitama, Japan.
| | - Ichiro Kita
- Department of Health Promotion Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University, Hachioji, Tokyo, Japan
| | - Shoko Shinoda
- Department of Health Promotion Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University, Hachioji, Tokyo, Japan
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3
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Du YT, Long Y, Tang W, Liu XF, Dai F, Zhou B. Prooxidative inhibition against NF-κB-mediated inflammation by pharmacological vitamin C. Free Radic Biol Med 2022; 180:85-94. [PMID: 35038551 DOI: 10.1016/j.freeradbiomed.2022.01.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 12/11/2021] [Accepted: 01/11/2022] [Indexed: 10/19/2022]
Abstract
Vitamin C (VC), widely found in vegetables and fruits, operates as an electron donor to perform various biological functions including anti-inflammatory activity. However, the mechanisms by which VC inhibits inflammation remain insufficiently understood. Accordingly, we performed a detail mechanistic study on anti-inflammatory activity of VC at millimolar (pharmacological) concentrations in lipopolysaccharides-stimulated RAW264.7 cells. It was found that VC and its two-electron oxidative product, dehydroascorbate (DHA) constructs an efficient redox cycle with the aid of intracellular glutathione and copper ions, thereby facilitating the generation of reactive oxygen species (ROS) and the ROS-dependent inhibition against the NF-κB-mediated inflammation.
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Affiliation(s)
- Yu-Ting Du
- State Key Laboratory of Applied Organic Chemistry, Lanzhou University, 222 Tianshui Street S., Lanzhou, Gansu, 730000, China; Department of Chemistry, Xinzhou Teachers University, Xinzhou, Shanxi, 034000, China
| | - Ying Long
- State Key Laboratory of Applied Organic Chemistry, Lanzhou University, 222 Tianshui Street S., Lanzhou, Gansu, 730000, China
| | - Wei Tang
- State Key Laboratory of Applied Organic Chemistry, Lanzhou University, 222 Tianshui Street S., Lanzhou, Gansu, 730000, China
| | - Xue-Feng Liu
- State Key Laboratory of Applied Organic Chemistry, Lanzhou University, 222 Tianshui Street S., Lanzhou, Gansu, 730000, China; School of Pharmacy, Lanzhou University, 222 Tianshui Street S., Lanzhou, Gansu, 730000, China
| | - Fang Dai
- State Key Laboratory of Applied Organic Chemistry, Lanzhou University, 222 Tianshui Street S., Lanzhou, Gansu, 730000, China
| | - Bo Zhou
- State Key Laboratory of Applied Organic Chemistry, Lanzhou University, 222 Tianshui Street S., Lanzhou, Gansu, 730000, China.
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4
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Mégier C, Peoc’h K, Puy V, Cordier AG. Iron Metabolism in Normal and Pathological Pregnancies and Fetal Consequences. Metabolites 2022; 12:metabo12020129. [PMID: 35208204 PMCID: PMC8876952 DOI: 10.3390/metabo12020129] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/23/2022] [Accepted: 01/25/2022] [Indexed: 02/04/2023] Open
Abstract
Iron is required for energy production, DNA synthesis, and cell proliferation, mainly as a component of the prosthetic group in hemoproteins and as part of iron-sulfur clusters. Iron is also a critical component of hemoglobin and plays an important role in oxygen delivery. Imbalances in iron metabolism negatively affect these vital functions. As the crucial barrier between the fetus and the mother, the placenta plays a pivotal role in iron metabolism during pregnancy. Iron deficiency affects 1.2 billion individuals worldwide. Pregnant women are at high risk of developing or worsening iron deficiency. On the contrary, in frequent hemoglobin diseases, such as sickle-cell disease and thalassemia, iron overload is observed. Both iron deficiency and iron overload can affect neonatal development. This review aims to provide an update on our current knowledge on iron and heme metabolism in normal and pathological pregnancies. The main molecular actors in human placental iron metabolism are described, focusing on the impact of iron deficiency and hemoglobin diseases on the placenta, together with normal metabolism. Then, we discuss data concerning iron metabolism in frequent pathological pregnancies to complete the picture, focusing on the most frequent diseases.
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Affiliation(s)
- Charles Mégier
- Assistance Publique-Hôpitaux de Paris, Service de Gynécologie-Obstétrique, Hôpital Bicêtre, Université Paris Saclay, 94270 Le Kremlin-Bicetre, France;
| | - Katell Peoc’h
- Assistance Publique-Hôpitaux de Paris, Laboratoire de Biochimie Clinique, HUPNVS, Hôpital Beaujon, Clichy and Université de Paris, UFR de Médecine Xavier Bichat, INSERM U1149, F-75018 Paris, France;
| | - Vincent Puy
- Unité de biologie de la Reproduction CECOS, Hôpital Antoine Béclère, Université Paris Saclay, 92140 Clamart, France;
- Laboratoire de Développement des Gonades, UMRE008 Stabilité Génétique Cellules Souches et Radiations, Université de Paris, Université Paris-Saclay, CEA, F-92265 Fontenay-aux-Roses, France
| | - Anne-Gaël Cordier
- INSERM, 3PHM, UMR-S1139, F-75006 Paris, France
- PremUp Foundation, F-75014 Paris, France
- Assistance Publique-Hôpitaux de Paris, Service de Gynécologie Obstétrique, Hôpital Antoine Béclère, Université Paris-Saclay, 92140 Clamart, France
- Correspondence: ; Tel.: +33-145374441; Fax: +33-45374366
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5
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Zhang YY, Stockmann R, Ng K, Ajlouni S. Opportunities for plant-derived enhancers for iron, zinc, and calcium bioavailability: A review. Compr Rev Food Sci Food Saf 2020; 20:652-685. [PMID: 33443794 DOI: 10.1111/1541-4337.12669] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 09/08/2020] [Accepted: 10/20/2020] [Indexed: 12/31/2022]
Abstract
Understanding of the mechanism of interactions between dietary elements, their salts, and complexing/binding ligands is vital to manage both deficiency and toxicity associated with essential element bioavailability. Numerous mineral ligands are found in both animal and plant foods and are known to exert bioactivity via element chelation resulting in modulation of antioxidant capacity or micobiome metabolism among other physiological outcomes. However, little is explored in the context of dietary mineral ligands and element bioavailability enhancement, particularly with respect to ligands from plant-derived food sources. This review highlights a novel perspective to consider various plant macro/micronutrients as prospective bioavailability enhancing ligands of three essential elements (Fe, Zn, and Ca). We also delineate the molecular mechanisms of the ligand-binding interactions underlying mineral bioaccessibility at the luminal level. We conclude that despite current understandings of some of the structure-activity relationships associated with strong mineral-ligand binding, the physiological links between ligands as element carriers and uptake at targeted sites throughout the gastrointestinal (GI) tract still require more research. The binding behavior of potential ligands in the human diet should be further elucidated and validated using pharmacokinetic approaches and GI models.
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Affiliation(s)
- Yianna Y Zhang
- School of Agriculture and Food, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, Australia.,CSIRO Agriculture & Food, Werribee, VIC, Australia
| | | | - Ken Ng
- School of Agriculture and Food, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, Australia
| | - Said Ajlouni
- School of Agriculture and Food, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, Australia
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6
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Lesjak M, K S Srai S. Role of Dietary Flavonoids in Iron Homeostasis. Pharmaceuticals (Basel) 2019; 12:E119. [PMID: 31398897 PMCID: PMC6789581 DOI: 10.3390/ph12030119] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2019] [Revised: 07/29/2019] [Accepted: 08/05/2019] [Indexed: 01/14/2023] Open
Abstract
Balancing systemic iron levels within narrow limits is critical for human health, as both iron deficiency and overload lead to serious disorders. There are no known physiologically controlled pathways to eliminate iron from the body and therefore iron homeostasis is maintained by modifying dietary iron absorption. Several dietary factors, such as flavonoids, are known to greatly affect iron absorption. Recent evidence suggests that flavonoids can affect iron status by regulating expression and activity of proteins involved the systemic regulation of iron metabolism and iron absorption. We provide an overview of the links between different dietary flavonoids and iron homeostasis together with the mechanism of flavonoids effect on iron metabolism. In addition, we also discuss the clinical relevance of state-of-the-art knowledge regarding therapeutic potential that flavonoids may have for conditions that are low in iron such as anaemia or iron overload diseases.
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Affiliation(s)
- Marija Lesjak
- Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg Dositeja Obradovića 3, 21000 Novi Sad, Serbia.
| | - Surjit K S Srai
- Research Department of Structural and Molecular Biology, Division of Biosciences, University College London, Darwin Building, Gower Street, London WC1E 6BT, UK.
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7
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Sherman HG, Jovanovic C, Abuawad A, Kim DH, Collins H, Dixon JE, Cavanagh R, Markus R, Stolnik S, Rawson FJ. Mechanistic insight into heterogeneity of trans-plasma membrane electron transport in cancer cell types. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2019; 1860:628-639. [DOI: 10.1016/j.bbabio.2019.06.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 06/18/2019] [Accepted: 06/19/2019] [Indexed: 12/28/2022]
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8
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Sherman HG, Jovanovic C, Stolnik S, Baronian K, Downard AJ, Rawson FJ. New Perspectives on Iron Uptake in Eukaryotes. Front Mol Biosci 2018; 5:97. [PMID: 30510932 PMCID: PMC6254016 DOI: 10.3389/fmolb.2018.00097] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 10/23/2018] [Indexed: 12/20/2022] Open
Abstract
All eukaryotic organisms require iron to function. Malfunctions within iron homeostasis have a range of physiological consequences, and can lead to the development of pathological conditions that can result in an excess of non-transferrin bound iron (NTBI). Despite extensive understanding of iron homeostasis, the links between the “macroscopic” transport of iron across biological barriers (cellular membranes) and the chemistry of redox changes that drive these processes still needs elucidating. This review draws conclusions from the current literature, and describes some of the underlying biophysical and biochemical processes that occur in iron homeostasis. By first taking a broad view of iron uptake within the gut and subsequent delivery to tissues, in addition to describing the transferrin and non-transferrin mediated components of these processes, we provide a base of knowledge from which we further explore NTBI uptake. We provide concise up-to-date information of the transplasma electron transport systems (tPMETSs) involved within NTBI uptake, and highlight how these systems are not only involved within NTBI uptake for detoxification but also may play a role within the reduction of metabolic stress through regeneration of intracellular NAD(P)H/NAD(P)+ levels. Furthermore, we illuminate the thermodynamics that governs iron transport, namely the redox potential cascade and electrochemical behavior of key components of the electron transport systems that facilitate the movement of electrons across the plasma membrane to the extracellular compartment. We also take account of kinetic changes that occur to transport iron into the cell, namely membrane dipole change and their consequent effects within membrane structure that act to facilitate transport of ions.
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Affiliation(s)
- Harry G Sherman
- Division of Regenerative Medicine and Cellular Therapies, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom
| | | | - Snow Stolnik
- Division of Molecular Therapeutics and Formulation, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom
| | - Kim Baronian
- School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - Alison J Downard
- MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Physical and Chemical Sciences, University of Canterbury, Christchurch, New Zealand
| | - Frankie J Rawson
- Division of Regenerative Medicine and Cellular Therapies, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom
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9
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Xiao L, Luo G, Tang Y, Yao P. Quercetin and iron metabolism: What we know and what we need to know. Food Chem Toxicol 2018; 114:190-203. [PMID: 29432835 DOI: 10.1016/j.fct.2018.02.022] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2017] [Revised: 01/18/2018] [Accepted: 02/07/2018] [Indexed: 12/14/2022]
Abstract
Iron is a life-supporting micronutrient that is required in the human diet, and is essential for maintaining physiological homeostasis. Properly harnessing a redox-active metal such as iron is a great challenge for cells and organisms because an excess of highly reactive iron catalyzes the formation of reactive oxygen species and can lead to cell and tissue damage. Quercetin is a typical flavonoid that is commonly found in fruits and vegetables and has versatile biological effects. From a classical viewpoint, owing to its unique chemical characteristics, quercetin has long been associated with iron metabolism only in the context of its iron-chelating and ROS-scavenging activities. However, within the field of human iron biology, expanding concepts of the roles of quercetin are flourishing, and great strides are being made in understanding the interactions between quercetin and iron. This progress highlights the varied roles of quercetin in iron metabolism, which involve much more than iron chelation alone. A review of these studies provides an ideal context to summarize recent progress and discuss compelling evidence for therapeutic opportunities that could arise from a better understanding of the underlying mechanisms.
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Affiliation(s)
- Lin Xiao
- Department of Nutrition and Food Hygiene, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China; Hubei Key Laboratory of Food Nutrition and Safety, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China; Ministry of Education Key Laboratory of Environment, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Gang Luo
- Department of Nutrition and Food Hygiene, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China; Hubei Key Laboratory of Food Nutrition and Safety, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China; Ministry of Education Key Laboratory of Environment, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Yuhan Tang
- Department of Nutrition and Food Hygiene, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China; Hubei Key Laboratory of Food Nutrition and Safety, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China; Ministry of Education Key Laboratory of Environment, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
| | - Ping Yao
- Department of Nutrition and Food Hygiene, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China; Hubei Key Laboratory of Food Nutrition and Safety, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China; Ministry of Education Key Laboratory of Environment, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
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10
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Abstract
Iron is an essential element for human development. It is a major requirement for cellular processes such as oxygen transport, energy metabolism, neurotransmitter synthesis, and myelin synthesis. Despite its crucial role in these processes, iron in the ferric form can also produce toxic reactive oxygen species. The duality of iron’s function highlights the importance of maintaining a strict balance of iron levels in the body. As a result, organisms have developed elegant mechanisms of iron uptake, transport, and storage. This review will focus on the mechanisms that have evolved at physiological barriers, such as the intestine, the placenta, and the blood–brain barrier (BBB), where iron must be transported. Much has been written about the processes for iron transport across the intestine and the placenta, but less is known about iron transport mechanisms at the BBB. In this review, we compare the established pathways at the intestine and the placenta as well as describe what is currently known about iron transport at the BBB and how brain iron uptake correlates with processes at these other physiological barriers.
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Affiliation(s)
- Kari A Duck
- Department of Neurosurgery, The Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - James R Connor
- Department of Neurosurgery, The Pennsylvania State University College of Medicine, Hershey, PA, USA.
- Department of Neurosurgery, Neural and Behavioral Sciences and Pediatrics, Center for Aging and Neurodegenerative Diseases, Penn State Hershey Medical Center, 500 University Drive, MC H110, C3830, Hershey, PA, 17033, USA.
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11
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Tedesco I, Moccia S, Volpe S, Alfieri G, Strollo D, Bilotto S, Spagnuolo C, Di Renzo M, Aquino RP, Russo GL. Red wine activates plasma membrane redox system in human erythrocytes. Free Radic Res 2016; 50:557-69. [PMID: 26866566 DOI: 10.3109/10715762.2016.1152629] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
In the present study, we report that polyphenols present in red wine obtained by a controlled microvinification process are able to protect human erythrocytes from oxidative stress and to activate Plasma Membrane Redox System (PMRS). Human plasma obtained from healthy subjects was incubated in the presence of whole red wine at a concentration corresponding to 9.13-73 μg/ml gallic acid equivalents to verify the capacity to protect against hypochlorous acid (HOCl)-induced plasma oxidation and to minimize chloramine formation. Red wine reduced hemolysis and chloramine formation induced by HOCl of 40 and 35%, respectively. PMRS present on human erythrocytes transfers electrons from intracellular molecules to extracellular electron acceptors. We demonstrated that whole red wine activated PMRS activity in human erythrocytes isolated from donors in a dose-dependent manner with a maximum at about 70-100 μg/ml gallic acid equivalents. We also showed that red wine increased glutathione (GSH) levels and erythrocytic antioxidant capacity, measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) quenching assay. Furthermore, we reported that GSH played a crucial role in regulating PMRS activity in erythrocytes. In fact, the effect of iodoacetamide, an alkylating agent that induces depletion of intracellular GSH, was completely counteracted by red wine. Bioactive compounds present in red wine, such as gallic acid, resveratrol, catechin, and quercetin were unable to activate PMRS when tested at the concentrations normally present in aged red wines. On the contrary, the increase of PMRS activity was associated with the anthocyanin fraction, suggesting the capacity of this class of compounds to positively modulate PMRS enzymatic activity.
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Affiliation(s)
- Idolo Tedesco
- a Institute of Food Sciences, National Research Council , Avellino , Italy
| | - Stefania Moccia
- a Institute of Food Sciences, National Research Council , Avellino , Italy
| | - Silvestro Volpe
- b Division of Onco-Hematology , S.G. Moscati Hospital , Avellino , Italy
| | - Giovanna Alfieri
- b Division of Onco-Hematology , S.G. Moscati Hospital , Avellino , Italy
| | | | - Stefania Bilotto
- a Institute of Food Sciences, National Research Council , Avellino , Italy
| | - Carmela Spagnuolo
- a Institute of Food Sciences, National Research Council , Avellino , Italy
| | | | - Rita P Aquino
- d Department of Pharmacy , University of Salerno , Fisciano (SA) , Italy
| | - Gian Luigi Russo
- a Institute of Food Sciences, National Research Council , Avellino , Italy
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12
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Duodenal cytochrome b (DCYTB) in iron metabolism: an update on function and regulation. Nutrients 2015; 7:2274-96. [PMID: 25835049 PMCID: PMC4425144 DOI: 10.3390/nu7042274] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2014] [Revised: 03/03/2015] [Accepted: 03/05/2015] [Indexed: 01/01/2023] Open
Abstract
Iron and ascorbate are vital cellular constituents in mammalian systems. The bulk-requirement for iron is during erythropoiesis leading to the generation of hemoglobin-containing erythrocytes. Additionally, both iron and ascorbate are required as co-factors in numerous metabolic reactions. Iron homeostasis is controlled at the level of uptake, rather than excretion. Accumulating evidence strongly suggests that in addition to the known ability of dietary ascorbate to enhance non-heme iron absorption in the gut, ascorbate regulates iron homeostasis. The involvement of ascorbate in dietary iron absorption extends beyond the direct chemical reduction of non-heme iron by dietary ascorbate. Among other activities, intra-enterocyte ascorbate appears to be involved in the provision of electrons to a family of trans-membrane redox enzymes, namely those of the cytochrome b561 class. These hemoproteins oxidize a pool of ascorbate on one side of the membrane in order to reduce an electron acceptor (e.g., non-heme iron) on the opposite side of the membrane. One member of this family, duodenal cytochrome b (DCYTB), may play an important role in ascorbate-dependent reduction of non-heme iron in the gut prior to uptake by ferrous-iron transporters. This review discusses the emerging relationship between cellular iron homeostasis, the emergent “IRP1-HIF2α axis”, DCYTB and ascorbate in relation to iron metabolism.
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13
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Wu CC, Chang WL, Lu CH, Chang YP, Wang JJ, Hsieh SL. Effects of extracts from Gynura bicolor (Roxb. & Willd.) DC. on iron bioavailability in rats. J Food Drug Anal 2015; 23:425-432. [PMID: 28911699 PMCID: PMC9351804 DOI: 10.1016/j.jfda.2014.11.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 08/19/2014] [Accepted: 11/24/2014] [Indexed: 11/24/2022] Open
Abstract
Gynura bicolor (Roxb. & Willd.) DC. is widely distributed in certain areas of Asia and is very popular in vegetarian cuisine in Taiwan. This study investigates the effects of G. bicolor extracts with different polarities of 80 mg/kg body weight (BW) G. bicolor alcohol extract, 80 mg/kg BW G. bicolor water extract, and 80 mg/kg BW G. bicolor ether extract on Fe bioavailability using the hemoglobin repletion efficiency assay. Wistar rats were assigned to five groups: a group receiving an iron-deficient (ID) diet; a group receiving an ID diet supplemented with ferrous sulfate (20 mg Fe/kg BW); and three groups receiving ID diets supplemented with ferrous sulfate and one of G. bicolor alcohol extract, G. bicolor water extract, or G. bicolor water extract. The results indicated that the levels of hemoglobin, serum iron, serum ferritin, liver ferritin, hemoglobin regeneration efficiency, relative biological value, and hepcidin all were significantly higher than those of the ID diet group. Besides, the iron transporter divalent metal transporter-1 was significantly reduced, but iron release protein expression of ferroportin was significantly increased. It was concluded that G. bicolor extracts may promote iron bioavailability and regulate the expressions of divalent metal transporter-1 and ferroportin.
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Affiliation(s)
- Chih-Chung Wu
- Department of Nutrition and Health Science, Chang Jung Christian University, Tainan, Taiwan
| | - Wei-Lin Chang
- Department of Seafood Science, National Kaohsiung Marine University, Kaohsiung, Taiwan
| | - Chih-Huei Lu
- Department of Physical Medicine and Rehabilitation, Fooyin University Hospital, Pingtung, Taiwan
| | - Yueh-Ping Chang
- Department of Nutrition and Health Science, Fooyin University, Kaohsiung, Taiwan
| | - Jyh-Jye Wang
- Department of Nutrition and Health Science, Fooyin University, Kaohsiung, Taiwan
| | - Shu-Ling Hsieh
- Department of Seafood Science, National Kaohsiung Marine University, Kaohsiung, Taiwan.
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14
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Gulec S, Anderson GJ, Collins JF. Mechanistic and regulatory aspects of intestinal iron absorption. Am J Physiol Gastrointest Liver Physiol 2014; 307:G397-409. [PMID: 24994858 PMCID: PMC4137115 DOI: 10.1152/ajpgi.00348.2013] [Citation(s) in RCA: 211] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Iron is an essential trace mineral that plays a number of important physiological roles in humans, including oxygen transport, energy metabolism, and neurotransmitter synthesis. Iron absorption by the proximal small bowel is a critical checkpoint in the maintenance of whole-body iron levels since, unlike most other essential nutrients, no regulated excretory systems exist for iron in humans. Maintaining proper iron levels is critical to avoid the adverse physiological consequences of either low or high tissue iron concentrations, as commonly occurs in iron-deficiency anemia and hereditary hemochromatosis, respectively. Exquisite regulatory mechanisms have thus evolved to modulate how much iron is acquired from the diet. Systemic sensing of iron levels is accomplished by a network of molecules that regulate transcription of the HAMP gene in hepatocytes, thus modulating levels of the serum-borne, iron-regulatory hormone hepcidin. Hepcidin decreases intestinal iron absorption by binding to the iron exporter ferroportin 1 on the basolateral surface of duodenal enterocytes, causing its internalization and degradation. Mucosal regulation of iron transport also occurs during low-iron states, via transcriptional (by hypoxia-inducible factor 2α) and posttranscriptional (by the iron-sensing iron-regulatory protein/iron-responsive element system) mechanisms. Recent studies demonstrated that these regulatory loops function in tandem to control expression or activity of key modulators of iron homeostasis. In health, body iron levels are maintained at appropriate levels; however, in several inherited disorders and in other pathophysiological states, iron sensing is perturbed and intestinal iron absorption is dysregulated. The iron-related phenotypes of these diseases exemplify the necessity of precisely regulating iron absorption to meet body demands.
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Affiliation(s)
- Sukru Gulec
- 1Food Science & Human Nutrition Department, University of Florida, Gainesville, Florida; and
| | | | - James F. Collins
- 1Food Science & Human Nutrition Department, University of Florida, Gainesville, Florida; and
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Heger M, van Golen RF, Broekgaarden M, Michel MC. The molecular basis for the pharmacokinetics and pharmacodynamics of curcumin and its metabolites in relation to cancer. Pharmacol Rev 2013; 66:222-307. [PMID: 24368738 DOI: 10.1124/pr.110.004044] [Citation(s) in RCA: 346] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
This review addresses the oncopharmacological properties of curcumin at the molecular level. First, the interactions between curcumin and its molecular targets are addressed on the basis of curcumin's distinct chemical properties, which include H-bond donating and accepting capacity of the β-dicarbonyl moiety and the phenylic hydroxyl groups, H-bond accepting capacity of the methoxy ethers, multivalent metal and nonmetal cation binding properties, high partition coefficient, rotamerization around multiple C-C bonds, and the ability to act as a Michael acceptor. Next, the in vitro chemical stability of curcumin is elaborated in the context of its susceptibility to photochemical and chemical modification and degradation (e.g., alkaline hydrolysis). Specific modification and degradatory pathways are provided, which mainly entail radical-based intermediates, and the in vitro catabolites are identified. The implications of curcumin's (photo)chemical instability are addressed in light of pharmaceutical curcumin preparations, the use of curcumin analogues, and implementation of nanoparticulate drug delivery systems. Furthermore, the pharmacokinetics of curcumin and its most important degradation products are detailed in light of curcumin's poor bioavailability. Particular emphasis is placed on xenobiotic phase I and II metabolism as well as excretion of curcumin in the intestines (first pass), the liver (second pass), and other organs in addition to the pharmacokinetics of curcumin metabolites and their systemic clearance. Lastly, a summary is provided of the clinical pharmacodynamics of curcumin followed by a detailed account of curcumin's direct molecular targets, whereby the phenotypical/biological changes induced in cancer cells upon completion of the curcumin-triggered signaling cascade(s) are addressed in the framework of the hallmarks of cancer. The direct molecular targets include the ErbB family of receptors, protein kinase C, enzymes involved in prostaglandin synthesis, vitamin D receptor, and DNA.
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Affiliation(s)
- Michal Heger
- Department of Experimental Surgery, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105AZ Amsterdam, The Netherlands.
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16
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Luo X, Hill M, Johnson A, Latunde-Dada GO. Modulation of Dcytb (Cybrd 1) expression and function by iron, dehydroascorbate and Hif-2α in cultured cells. Biochim Biophys Acta Gen Subj 2013; 1840:106-12. [PMID: 23981688 DOI: 10.1016/j.bbagen.2013.08.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 07/24/2013] [Accepted: 08/17/2013] [Indexed: 01/25/2023]
Abstract
BACKGROUND Duodenal cytochrome b (Dcytb) is a mammalian plasma ferric reductase enzyme that catalyses the reduction of ferric to ferrous ion in the process of iron absorption. The current study investigates the relationship between Dcytb, iron, dehydroascorbate (DHA) and Hif-2α in cultured cell lines. METHODS Dcytb and Hif-2α protein expression was analysed by Western blot technique while gene regulation was determined by quantitative PCR. Functional analyses were carried out by ferric reductase and (59)Fe uptake assays. RESULTS Iron and dehydroascorbic acid treatment of cells inhibited Dcytb mRNA and protein expression. Desferrioxamine also enhanced Dcytb mRNA level after cells were treated overnight. Dcytb knockdown in HuTu cells resulted in reduced mRNA expression and lowered reductase activity. Preloading cells with DHA (to enhance intracellular ascorbate levels) did not stimulate reductase activity fully in Dcytb-silenced cells, implying a Dcytb-dependence of ascorbate-mediated ferrireduction. Moreover, Hif-2α knockdown in HuTu cells led to a reduction in reductase activity and iron uptake. CONCLUSIONS Taken together, this study shows the functional regulation of Dcytb reductase activity by DHA and Hif-2α. GENERAL SIGNIFICANCE Dcytb is a plasma membrane protein that accepts electrons intracellularly from DHA/ascorbic acid for ferrireduction at the apical surface of cultured cells and enterocytes.
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Affiliation(s)
- Xiaomin Luo
- Diabetes and Nutritional Sciences Division, King's College London, London, UK
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17
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Li Y, Deng Y, Tang Y, Yu H, Gao C, Liu L, Liu L, Yao P. Quercetin protects rat hepatocytes from oxidative damage induced by ethanol and iron by maintaining intercellular liable iron pool. Hum Exp Toxicol 2013; 33:534-41. [PMID: 23928830 DOI: 10.1177/0960327113499168] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Accumulating evidence has shown that ethanol-induced iron overload plays a crucial role in the development and progression of alcoholic liver disease. We designed the present study to investigate the potential protective effect of quercetin, a naturally occurring iron-chelating antioxidant on alcoholic iron overload and oxidative stress. Ethanol-incubated (100 mmol/L) rat primary hepatocytes were co-treated by quercetin (100 µmol/L) and different dose of ferric nitrilotriacetate (Fe-NTA) for 24 h. When the hepatic enzyme releases in the culture medium, redox status of hepatocytes and the intercellular labile iron pool (LIP) level were assayed. Our data showed that Fe-NTA dose dependently induced cellular leakage of aspartate transaminase and lactate dehydrogenase, glutathione depletion, superoxide dismutase inactivation, and overproduction of malondialdehyde) and reactive oxygen species (ROS) of intact and especially ethanol-incubated hepatocytes. The oxidative damage resulted from ethanol, Fe-NTA, and especially their combined treatment was substantially alleviated by quercetin, accompanying the corresponding normalization of intercellular LIP level. Iron in excess, thus, may aggravate ethanol hepatotoxicity through Fenton-active LIP, and quercetin attenuated ethanol-induced iron and oxidative stress. To maintain intercellular LIP contributes to the hepatoprotective effect of quercetin besides its direct ROS-quenching activity.
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Affiliation(s)
- Y Li
- 1Department of Nutrition and Food Hygiene, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
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Recuenco MC, Rahman MM, Takeuchi F, Kobayashi K, Tsubaki M. Electron transfer reactions of candidate tumor suppressor 101F6 protein, a cytochrome b561 homologue, with ascorbate and monodehydroascorbate radical. Biochemistry 2013; 52:3660-8. [PMID: 23641721 DOI: 10.1021/bi301607s] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The candidate tumor suppressor 101F6 protein is a homologue of adrenal chromaffin granule cytochrome b561, which is involved in the electron transfer from cytosolic ascorbate to intravesicular monodehydroascorbate radical. Since the tumor suppressor activity of 101F6 was enhanced in the presence of ascorbate, it was suggested that 101F6 might utilize a similar transmembrane electron transfer reaction. Detailed kinetic analyses were conducted on the detergent-solubilized recombinant human 101F6 for its electron transfer reactions with ascorbate and monodehydroascorbate radical by stopped-flow and pulse radiolysis techniques. The reduction of oxidized 101F6 with ascorbate was found to be independent of pH in contrast to those observed for chromaffin granule and Zea mays cytochromes b561 in which both cytochromes exhibited very slow rates at pH 5.0 but faster at pH 6.0 and 7.0. The absence of the inhibition for the electron acceptance from ascorbate upon the treatment with diethyl pyrocarbonate suggested that 101F6 might not utilize a "concerted proton/electron transfer mechanism". The second-order rate constant for the electron donation from the ascorbate-reduced 101F6 to the pulse-generated monodehydroascorbate radical was found to be 5.0 × 10(7) M(-1 )s(-1), about 2-fold faster than that of bovine chromaffin granule cytochrome b561 and about five times faster than that of Zea mays cytochrome b561, suggesting that human 101F6 is very effective for regenerating ascorbate from monodehydroascorbate radical in cells. Present observations suggest that 101F6 employs distinct electron transfer mechanisms on both sides of the membranes from those of other members of cytochrome b561 protein family.
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Affiliation(s)
- Mariam C Recuenco
- Department of Chemistry, Graduate School of Science, Kobe University , Rokkodai-cho 1-1, Nada-ku, Kobe, Hyogo 657-8501, Japan
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Loke SY, Siddiqi NJ, Alhomida AS, Kim HC, Ong WY. Expression and localization of duodenal cytochrome b in the rat hippocampus after kainate-induced excitotoxicity. Neuroscience 2013; 245:179-90. [PMID: 23597830 DOI: 10.1016/j.neuroscience.2013.04.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Revised: 03/30/2013] [Accepted: 04/06/2013] [Indexed: 11/24/2022]
Abstract
Brain iron accumulation and oxidative stress are common features of many neurodegenerative diseases, and could be due in part to increased iron influx across the blood-brain interface. The iron transport protein, divalent metal transporter 1 (DMT1) is found in reactive astrocytes of the lesioned hippocampal CA fields after excitotoxicity induced by the glutamate analog kainate (KA), but in order for iron to be transported by DMT1, it must be converted from the ferric to the ferrous form. The present study was carried out to investigate the expression of a ferric reductase, duodenal cytochrome b (DCYTB), in the rat hippocampus after KA injury. Quantitative reverse transcriptase-polymerase chain reaction showed significant increases in DCYTB mRNA expression of 2.5, 2.7, and 5.2-fold in the hippocampus at 1week, 2weeks and 1month post-KA lesions respectively compared to untreated controls, and 3.0-fold compared to 1month post-saline injection. DCYTB-positive cells were double labeled with glial fibrillary acidic protein, and electron microscopy showed that the DCYTB-positive cells had dense bundles of glial filaments, characteristic of astrocytes, and were present as end-feet around unlabeled brain capillary endothelial cells. DMT1 labeling in astrocytes and increased iron staining were also observed in the lesioned hippocampus. Together, the present findings of DCYTB and DMT1 localization in astrocytes suggest that DCYTB is a ferric reductase for reduction of ferric iron, for transport by DMT1 into the brain. We postulate that the coordinated action of these two proteins could be important in iron influx across the blood-brain interface, in areas undergoing neurodegeneration.
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Affiliation(s)
- S-Y Loke
- Department of Anatomy, National University of Singapore, Singapore 119260, Singapore
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Casuso RA, Martínez-Amat A, Martínez-López EJ, Camiletti-Moirón D, Porres JM, Aranda P. Ergogenic effects of quercetin supplementation in trained rats. J Int Soc Sports Nutr 2013; 10:3. [PMID: 23316871 PMCID: PMC3549753 DOI: 10.1186/1550-2783-10-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 12/19/2012] [Indexed: 12/21/2022] Open
Abstract
UNLABELLED BACKGROUND Quercetin is a natural polyphenolic compound currently under study for its ergogenic capacity to improve mitochondrial biogenesis. Sedentary mice have exhibited increased endurance performance, but results are contradictory in human models. METHODS We examined the effects of six weeks of endurance training and quercetin supplementation on markers of endurance performance and training in a rodent model. Rats were randomly assigned to one of the following groups: placebo+sedentary (PS), quercetin+sedentary (QS), placebo+endurance training (PT) and quercetin+endurance training (QT). Quercetin was administered at a dose of 25 mg/kg on alternate days. During six weeks of treatment volume parameters of training were recorded, and after six weeks all groups performed a maximal graded VO2 max test and a low-intensity endurance run-to-fatigue test. RESULTS No effects were found in VO2 peak (p>0.999), nor in distance run during low-intensity test, although it was 14% greater in QT when compared with PT (P = 0.097). Post-exercise blood lactate was increased in QT when compared with PT (p=0.023) and also in QS compared with PS (p=0.024). CONCLUSIONS This study showed no effects in VO2 peak, speed at VO2 peak or endurance time to exhaustion after six weeks of quercetin supplementation compared with placebo in trained rats. Quercetin was show to increase blood lactate production after high-intensity exercise.
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Affiliation(s)
- Rafael A Casuso
- Department of Health Sciences, University of Jaén, Jaén, E-23071, Spain.
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Davies JL, Cazier JB, Dunlop MG, Houlston RS, Tomlinson IP, Holmes CC. A novel test for gene-ancestry interactions in genome-wide association data. PLoS One 2012; 7:e48687. [PMID: 23236349 PMCID: PMC3516524 DOI: 10.1371/journal.pone.0048687] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Accepted: 10/01/2012] [Indexed: 01/03/2023] Open
Abstract
Genome-wide association study (GWAS) data on a disease are increasingly available from multiple related populations. In this scenario, meta-analyses can improve power to detect homogeneous genetic associations, but if there exist ancestry-specific effects, via interactions on genetic background or with a causal effect that co-varies with genetic background, then these will typically be obscured. To address this issue, we have developed a robust statistical method for detecting susceptibility gene-ancestry interactions in multi-cohort GWAS based on closely-related populations. We use the leading principal components of the empirical genotype matrix to cluster individuals into “ancestry groups” and then look for evidence of heterogeneous genetic associations with disease or other trait across these clusters. Robustness is improved when there are multiple cohorts, as the signal from true gene-ancestry interactions can then be distinguished from gene-collection artefacts by comparing the observed interaction effect sizes in collection groups relative to ancestry groups. When applied to colorectal cancer, we identified a missense polymorphism in iron-absorption gene CYBRD1 that associated with disease in individuals of English, but not Scottish, ancestry. The association replicated in two additional, independently-collected data sets. Our method can be used to detect associations between genetic variants and disease that have been obscured by population genetic heterogeneity. It can be readily extended to the identification of genetic interactions on other covariates such as measured environmental exposures. We envisage our methodology being of particular interest to researchers with existing GWAS data, as ancestry groups can be easily defined and thus tested for interactions.
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Affiliation(s)
- Joanna L. Davies
- Department of Statistics, University of Oxford, Oxford, United Kingdom
| | - Jean-Baptiste Cazier
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Malcolm G. Dunlop
- Colon Cancer Genetics Group, Institute of Genetics and Molecular Medicine, University of Edinburgh and Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh, Scotland, United Kingdom
| | - Richard S. Houlston
- Section of Cancer Genetics, Institute of Cancer Research, Sutton, Surrey, United Kingdom
| | - Ian P. Tomlinson
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
- Oxford Comprehensive Biomedical Research Centre, John Radcliffe Hospital, Headington, Oxford, United Kingdom
| | - Chris C. Holmes
- Department of Statistics, University of Oxford, Oxford, United Kingdom
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
- MRC Harwell, Harwell Science and Innovation Campus, Oxfordshire, United Kingdom
- * E-mail:
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Sadowska-Woda I, Bartosz G. How do erythrocytes contribute to the ABTS* scavenging capacity of blood? Free Radic Res 2012; 47:35-43. [PMID: 23025487 DOI: 10.3109/10715762.2012.734611] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
It has been suggested lately that erythrocytes contribute significantly to the oxidant scavenging capacity (OSC) of blood and that surface adsorption of polyphenols enhances the antioxidant capacity of erythrocytes. The aim of this study was to examine the contribution of erythrocytes to the OSC of whole blood measured with a substrate not penetrating into the cells. Comparison of reduction of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical (ABTS*) by whole blood and blood plasma indicates that erythrocytes do contribute to ABTS* reduction but their contribution is lower with respect to plasma. ABTS* reduction by erythrocytes and its enhancement by polyphenols were inhibited by thiol reagents (N-ethylmaleimide and iodacetate). These reagents inhibited also the reduction of extracellular ferricyanide by erythrocytes and its enhancement by polyphenols. On this basis we postulate that the contribution of erythrocytes to the blood OSC estimated by ABTS* decolorization is at least partly due to the transmembrane-reducing system, which activity is routinely assayed by ferricyanide reduction.
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Vlachodimitropoulou E, Sharp PA, Naftalin RJ. Quercetin-iron chelates are transported via glucose transporters. Free Radic Biol Med 2011; 50:934-44. [PMID: 21238582 DOI: 10.1016/j.freeradbiomed.2011.01.005] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 12/31/2010] [Accepted: 01/06/2011] [Indexed: 10/18/2022]
Abstract
Flavonoids are well-known antioxidants and free radical scavengers. Their metal-binding activity suggests that they could be effective protective agents in pathological conditions caused by both extracellular and intracellular oxidative stress linked to metal overload. Quercetin is both a permeant ligand via glucose transport proteins (GLUTs) and a high-affinity inhibitor of GLUT-mediated glucose transport. Chelatable "free iron" at micromolar concentrations in body fluids is a catalyst of hydroxyl radical (OH(•)) production from hydrogen peroxide. A number of flavonoids, e.g., quercetin, luteolin, chrysin, and 3,6-dihydroxyflavone, have been demonstrated to chelate intracellular iron and suppress OH(•) radical production in Madin Darby canine kidney cells. The most effective chelation comes from the flavonone B ring catechol found in both quercetin and luteolin. We show here that quercetin concentrations of <1μM can facilitate chelatable iron shuttling via GLUT1 in either direction across the cell membrane. These siderophoric effects are inhibited by raised quercetin concentrations (>1μM) or GLUT inhibitors, e.g., phloretin or cytochalasin B, and iron efflux is enhanced by impermeant extracellular iron chelators, either desferrioxamine or rutin. This iron shuttling property of quercetin might be usefully harnessed in chelotherapy of iron-overload conditions.
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Kell DB. Towards a unifying, systems biology understanding of large-scale cellular death and destruction caused by poorly liganded iron: Parkinson's, Huntington's, Alzheimer's, prions, bactericides, chemical toxicology and others as examples. Arch Toxicol 2010; 84:825-89. [PMID: 20967426 PMCID: PMC2988997 DOI: 10.1007/s00204-010-0577-x] [Citation(s) in RCA: 286] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Accepted: 07/14/2010] [Indexed: 12/11/2022]
Abstract
Exposure to a variety of toxins and/or infectious agents leads to disease, degeneration and death, often characterised by circumstances in which cells or tissues do not merely die and cease to function but may be more or less entirely obliterated. It is then legitimate to ask the question as to whether, despite the many kinds of agent involved, there may be at least some unifying mechanisms of such cell death and destruction. I summarise the evidence that in a great many cases, one underlying mechanism, providing major stresses of this type, entails continuing and autocatalytic production (based on positive feedback mechanisms) of hydroxyl radicals via Fenton chemistry involving poorly liganded iron, leading to cell death via apoptosis (probably including via pathways induced by changes in the NF-κB system). While every pathway is in some sense connected to every other one, I highlight the literature evidence suggesting that the degenerative effects of many diseases and toxicological insults converge on iron dysregulation. This highlights specifically the role of iron metabolism, and the detailed speciation of iron, in chemical and other toxicology, and has significant implications for the use of iron chelating substances (probably in partnership with appropriate anti-oxidants) as nutritional or therapeutic agents in inhibiting both the progression of these mainly degenerative diseases and the sequelae of both chronic and acute toxin exposure. The complexity of biochemical networks, especially those involving autocatalytic behaviour and positive feedbacks, means that multiple interventions (e.g. of iron chelators plus antioxidants) are likely to prove most effective. A variety of systems biology approaches, that I summarise, can predict both the mechanisms involved in these cell death pathways and the optimal sites of action for nutritional or pharmacological interventions.
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Affiliation(s)
- Douglas B Kell
- School of Chemistry and the Manchester Interdisciplinary Biocentre, The University of Manchester, Manchester M1 7DN, UK.
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