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Mason SA, Parker L, van der Pligt P, Wadley GD. Vitamin C supplementation for diabetes management: A comprehensive narrative review. Free Radic Biol Med 2023; 194:255-283. [PMID: 36526243 DOI: 10.1016/j.freeradbiomed.2022.12.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 12/01/2022] [Accepted: 12/05/2022] [Indexed: 12/15/2022]
Abstract
Growing evidence suggests that vitamin C supplementation may be an effective adjunct therapy in the management of people with diabetes. This paper critically reviews the current evidence on effects of vitamin C supplementation and its potential mechanisms in diabetes management. Evidence from meta-analyses of randomized controlled trials (RCTs) show favourable effects of vitamin C on glycaemic control and blood pressure that may be clinically meaningful, and mixed effects on blood lipids and endothelial function. However, evidence is mostly of low evidence certainty. Emerging evidence is promising for effects of vitamin C supplementation on some diabetes complications, particularly diabetic foot ulcers. However, there is a notable lack of robust and well-designed studies exploring effects of vitamin C as a single compound supplement on diabetes prevention and patient-important outcomes (i.e. prevention and amelioration of diabetes complications). RCTs are also required to investigate potential preventative or ameliorative effects of vitamin C on gestational diabetes outcomes. Oral vitamin C doses of 500-1000 mg per day are potentially effective, safe, and affordable for many individuals with diabetes. However, personalisation of supplementation regimens that consider factors such as vitamin C status, disease status, current glycaemic control, vitamin C intake, redox status, and genotype is important to optimize vitamin C's therapeutic effects safely. Finally, given a high prevalence of vitamin C deficiency in patients with complications, it is recommended that plasma vitamin C concentration be measured and monitored in the clinic setting.
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Affiliation(s)
- Shaun A Mason
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia.
| | - Lewan Parker
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - Paige van der Pligt
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia; Department of Nutrition and Dietetics, Western Health, Footscray, Australia
| | - Glenn D Wadley
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
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2
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Lykkesfeldt J. On the effect of vitamin C intake on human health: How to (mis)interprete the clinical evidence. Redox Biol 2020; 34:101532. [PMID: 32535545 PMCID: PMC7296342 DOI: 10.1016/j.redox.2020.101532] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 03/30/2020] [Accepted: 03/31/2020] [Indexed: 02/07/2023] Open
Abstract
For decades, the potential beneficial effect of vitamin C on human health-beyond that of preventing scurvy-has been subject of much controversy. Hundreds of articles have appeared either in support of increased vitamin C intake through diet or supplements or rejecting the hypothesis that increased intake of vitamin C or supplementation may influence morbidity and mortality. The chemistry and pharmacology of vitamin C is complex and has unfortunately rarely been taken into account when designing clinical studies testing its effect on human health. However, ignoring its chemical lability, dose-dependent absorption and elimination kinetics, distribution via active transport, or complex dose-concentration-response relationships inevitably leads to poor study designs, inadequate inclusion and exclusion criteria and misinterpretation of results. The present review outlines the differences in vitamin C pharmacokinetics compared to normal low molecular weight drugs, focusses on potential pitfalls in study design and data interpretation, and re-examines major clinical studies of vitamin C in light of these.
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Affiliation(s)
- Jens Lykkesfeldt
- Faculty of Health & Medical Sciences, University of Copenhagen, DK-1870, Frederiksberg C, Denmark.
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Peña E, Roa FJ, Inostroza E, Sotomayor K, González M, Gutierrez-Castro FA, Maurin M, Sweet K, Labrousse C, Gatica M, Aylwin CF, Mendoza P, Maldonado M, Delgado C, Madariaga J, Panes J, Silva-Grecchi T, Concha II, Moraga-Cid G, Reyes AM, Muñoz-Montesino C, Vera JC, Rivas CI. Increased expression of mitochondrial sodium-coupled ascorbic acid transporter-2 (mitSVCT2) as a central feature in breast cancer. Free Radic Biol Med 2019; 135:283-292. [PMID: 30902760 DOI: 10.1016/j.freeradbiomed.2019.03.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 03/07/2019] [Accepted: 03/12/2019] [Indexed: 12/20/2022]
Abstract
The potential role of vitamin C in cancer prevention and treatment remains controversial. While normal human cells obtain vitamin C as ascorbic acid, the prevalent form of vitamin C in vivo, the uptake mechanisms by which cancer cells acquire vitamin C has remained unclear. The aim of this study is to characterize how breast cancer cells acquire vitamin C. For this, we determined the expression of vitamin C transporters in normal and breast cancer tissue samples, and in ZR-75, MCF-7, MDA-231 and MDA-468 breast cancer cell lines. At the same time, reduced (AA) and oxidized (DHA) forms of vitamin C uptake experiments were performed in all cell lines. We show here that human breast cancer tissues differentially express a form of SVCT2 transporter, that is systematically absent in normal breast tissues and it is increased in breast tumors. In fact, estrogen receptor negative breast cancer tissue, exhibit the most elevated SVCT2 expression levels. Despite this, our analysis in breast cancer cell lines showed that these cells are not able to uptake ascorbic acid and depend on glucose transporter for the acquisition of vitamin C by a bystander effect. This is consistent with our observations that this form of SVCT2 is completely absent from the plasma membrane and is overexpressed in mitochondria of breast cancer cells, where it mediates ascorbic acid transport. This work shows that breast cancer cells acquire vitamin C in its oxidized form and are capable of accumulated high concentrations of the reduced form. Augmented expression of an SVCT2 mitochondrial form appears to be a common hallmark across all human cancers and might have implications in cancer cells survival capacity against pro-oxidant environments.
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Affiliation(s)
- Eduardo Peña
- Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Barrio Universitario s/n, PO Box 160C, Concepción, Chile
| | - Francisco J Roa
- Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Barrio Universitario s/n, PO Box 160C, Concepción, Chile
| | - Eveling Inostroza
- Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Barrio Universitario s/n, PO Box 160C, Concepción, Chile
| | - Kirsty Sotomayor
- Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Barrio Universitario s/n, PO Box 160C, Concepción, Chile
| | - Mauricio González
- Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Barrio Universitario s/n, PO Box 160C, Concepción, Chile
| | - Francisco A Gutierrez-Castro
- Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Barrio Universitario s/n, PO Box 160C, Concepción, Chile
| | - Michelle Maurin
- Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Barrio Universitario s/n, PO Box 160C, Concepción, Chile
| | - Karen Sweet
- Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Barrio Universitario s/n, PO Box 160C, Concepción, Chile
| | - Claire Labrousse
- Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Barrio Universitario s/n, PO Box 160C, Concepción, Chile
| | - Marcell Gatica
- Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Barrio Universitario s/n, PO Box 160C, Concepción, Chile
| | - Carlos F Aylwin
- Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Barrio Universitario s/n, PO Box 160C, Concepción, Chile
| | - Pamela Mendoza
- Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Barrio Universitario s/n, PO Box 160C, Concepción, Chile
| | - Mafalda Maldonado
- Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Barrio Universitario s/n, PO Box 160C, Concepción, Chile
| | - Carolina Delgado
- Departamento de Especialidades Médicas, Facultad de Medicina, Universidad de Concepción, Barrio Universitario s/n, PO Box 160C, Concepción, Chile
| | - Jaime Madariaga
- Departamento de Especialidades Médicas, Facultad de Medicina, Universidad de Concepción, Barrio Universitario s/n, PO Box 160C, Concepción, Chile
| | - Jessica Panes
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Barrio Universitario s/n, PO Box 160C, Concepción, Chile
| | - Tiare Silva-Grecchi
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Barrio Universitario s/n, PO Box 160C, Concepción, Chile
| | - Ilona I Concha
- Instituto de Bioquímica y Microbiología, Facultad de Ciencias, Universidad Austral de Chile, Campus Isla Teja, PO Box 567, Valdivia, Chile
| | - Gustavo Moraga-Cid
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Barrio Universitario s/n, PO Box 160C, Concepción, Chile
| | - Alejandro M Reyes
- Instituto de Bioquímica y Microbiología, Facultad de Ciencias, Universidad Austral de Chile, Campus Isla Teja, PO Box 567, Valdivia, Chile
| | - Carola Muñoz-Montesino
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Barrio Universitario s/n, PO Box 160C, Concepción, Chile.
| | - Juan Carlos Vera
- Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Barrio Universitario s/n, PO Box 160C, Concepción, Chile
| | - Coralia I Rivas
- Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Barrio Universitario s/n, PO Box 160C, Concepción, Chile.
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Da Silva LM, da Silva RDCMVDAF, Maria-Ferreira D, Beltrame OC, da Silva-Santos JE, Werner MFDP. Vitamin C Improves Gastroparesis in Diabetic Rats: Effects on Gastric Contractile Responses and Oxidative Stress. Dig Dis Sci 2017. [PMID: 28639130 DOI: 10.1007/s10620-017-4632-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Diabetic gastroparesis is a common complication of diabetes mellitus, which mainly affects women. Previous studies have demonstrated that oxidative stress is involved in its onset and development. AIMS This study evaluated the role of vitamin C on diabetes-associated gastric dysmotility. METHODS Female rats with streptozotocin-induced diabetes were treated with vehicle (water, 1 mL/kg, p.o.), vitamin C (300 mg/kg/day, p.o.), or insulin (6 IU/day, s.c.). Gastric emptying, in vitro gastric contractility, and biochemistry parameters were analyzed at the end of the treatment (i.e. 8 weeks after the diabetes induction). RESULTS Vitamin C reversed the delayed gastric emptying of diabetic rats to normal levels, and avoided the changes in the contractile responses to acetylcholine (0.1 nM-1 µM), but not to 5-hydroxytryptamine (0.1 nM-1 µM), in the pylorus and fundus from diabetic rats. Moreover, the contraction evoked by KCl (40 mM) in the fundus, but not in the pylorus, was intensely increased in diabetic rats treated with vitamin C. Notably, the vitamin C reestablished the reduced glutathione levels by 77% and decreased the reactive oxygen species content by 60% in the gastric tissue from diabetic rats. Despite the effects on gastric motility, vitamin C treatment did not change the fasting glycaemia or the glycated hemoglobin of diabetic rats. Unsurprisingly, insulin treatment normalized all parameters evaluated. CONCLUSIONS Vitamin C exhibited a remarkable beneficial effect on gastric emptying dysfunction in diabetic rats, which was mediated by attenuation of oxidative stress and maintenance of the cholinergic contractile responses in fundus and pylorus.
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Affiliation(s)
- Luisa Mota Da Silva
- Departamento de Farmacologia, Setor de Ciências Biológicas, Universidade Federal do Paraná, Curitiba, PR, Brazil. .,Programa de Pós-Graduação em Ciências Farmacêuticas, Centro de Ciências da Saúde, Universidade do Vale do Itajaí, Itajaí, SC, Brazil.
| | | | - Daniele Maria-Ferreira
- Departamento de Farmacologia, Setor de Ciências Biológicas, Universidade Federal do Paraná, Curitiba, PR, Brazil
| | - Olair Carlos Beltrame
- Departamento de Medicina Veterinária, Hospital Veterinário, Universidade Federal do Paraná, Curitiba, PR, Brazil
| | - José Eduardo da Silva-Santos
- Laboratory of Cardiovascular Biology, Department of Pharmacology, Center of Biological Sciences, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
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5
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Gillani SW, Sulaiman SAS, Abdul MIM, Baig MR. Combined effect of metformin with ascorbic acid versus acetyl salicylic acid on diabetes-related cardiovascular complication; a 12-month single blind multicenter randomized control trial. Cardiovasc Diabetol 2017; 16:103. [PMID: 28807030 PMCID: PMC5556597 DOI: 10.1186/s12933-017-0584-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 07/31/2017] [Indexed: 12/11/2022] Open
Abstract
Background We aimed to investigate the efficacy of ascorbic acid and acetylsalicylic acid among type II diabetes mellitus patients using metformin (only) for diabetes management therapy. Method A 12-month single blinded multicenter randomized control trial was designed to investigate the measured variables [Glycated Hemoglobin (HbA1c), Renal function, Albumin Creatinine Ratio (ACR) etc.]. The trial was randomized into 2 experimental parallel arms (ascorbic acid vs acetylsalicylic acid) were blinded with study supplements in combination with metformin and findings were compared to control arm with metformin alone and blinded with placebo. Withdrawal criteria was defined to maintain the equity and balance in the participants in the whole trial. Finding Patients with metformin and ascorbic acid (parallel arm I) was twice more likely to reduce HbA1c than metformin alone (control arm) in a year (OR 2.31 (95% CI 1.87–4.42) p < 0.001). Also Parallel arm I was ten times more likely to reduced risk factors contributing to long-term diabetes complications than participants of arm II in a year (OR 10.38 (95% CI 6.91–15.77) p < 0.001). In contrast, parallel arm II patients were seven times more effective to reduce the risk of expected CVD development in 10 years than arm I (OR 7.54 (95% CI 3.76–10.32) p < 0.001). Conclusions The trial concluded that ascorbic acid with metformin is more effective against reducing risks for diabetes related long-term complications (including ACR). TRIAL details Registration No: NTR-6100, Registry Name: Netherlands Trial Registry, URL: http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=6100, Date of Registration: 20th October, 2016, Date of first Enrollment: 1 November, 2015. Electronic supplementary material The online version of this article (doi:10.1186/s12933-017-0584-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Syed Wasif Gillani
- College of Pharmacy, Taibah University, Medina, Al-Madinah Munawarah, Saudi Arabia. .,Pharmacotherapy Research Group, Islamabad, Pakistan. .,Pharmacotherapy Research Group, Kuala Lumpur, Malaysia.
| | | | - Mohi Iqbal Mohammad Abdul
- College of Pharmacy, Taibah University, Medina, Al-Madinah Munawarah, Saudi Arabia.,College of Pharmacy, University of Philippines, Quezon, Philippines
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Khodaeian M, Tabatabaei-Malazy O, Qorbani M, Farzadfar F, Amini P, Larijani B. Effect of vitamins C and E on insulin resistance in diabetes: a meta-analysis study. Eur J Clin Invest 2015; 45:1161-74. [PMID: 26313310 DOI: 10.1111/eci.12534] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2015] [Accepted: 08/24/2015] [Indexed: 12/21/2022]
Abstract
BACKGROUND Data regarding the effect of vitamin C (VC) and vitamin E (VE) supplementation on insulin resistance in type 2 diabetes mellitus (T2DM) are controversial. We aimed to systematically review the current data on this topic. MATERIALS AND METHODS All randomized controlled trials (RCTs) conducted to assess the effect of VC and/or VE on insulin resistance in diabetes published in Google Scholar and PubMed web databases until January 2014 were included. Exclusion criteria were studies conducted in animal, type 1 DM, children or pregnant women. Main outcome measure was insulin resistance by homoeostasis model assessment (HOMA) index. According to degree of heterogeneity, fixed- or random-effect model was employed by stata software (11.0). RESULTS We selected 14 RCTs involving 735 patients with T2DM. VE or mixture-mode supplementation did not have any significant effect on HOMA with a standardized mean difference (SMD): 0·017, 95% CI: -0·376 to 0·411 (P = 0·932); and SMD: -0·035, 95% CI: -0·634 to 0·025 (P = 0·070), respectively, by random-effect model. VC supplement alone did not improve insulin resistance with a SMD: -0·150, 95% CI: -0·494 to 0·194 (P = 0·391), by fixed-effect model. Meta-regression test demonstrated that HOMA index may have not been influenced by the year of publication, dosage or duration of treatment. CONCLUSIONS The sole intake of VC, VE or their combination with other antioxidants could not improve insulin resistance in diabetes.
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Affiliation(s)
- Mehrnoosh Khodaeian
- Endocrinology and Metabolism Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Ozra Tabatabaei-Malazy
- Diabetes Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Mostafa Qorbani
- Department of Community Medicine, School of Medicine, Alborz University of Medical Sciences, Karaj, Iran.,Non-Communicable Disease Research Center, Endocrinology and Metabolism Population Sciences Institute, Tehran university of Medical Sciences, Tehran, Iran
| | - Farshad Farzadfar
- Non-Communicable Disease Research Center, Endocrinology and Metabolism Population Sciences Institute, Tehran university of Medical Sciences, Tehran, Iran
| | - Peyvand Amini
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, USA
| | - Bagher Larijani
- Endocrinology and Metabolism Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
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7
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Du J, Cullen JJ, Buettner GR. Ascorbic acid: chemistry, biology and the treatment of cancer. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1826:443-57. [PMID: 22728050 PMCID: PMC3608474 DOI: 10.1016/j.bbcan.2012.06.003] [Citation(s) in RCA: 478] [Impact Index Per Article: 39.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Revised: 06/11/2012] [Accepted: 06/13/2012] [Indexed: 12/14/2022]
Abstract
Since the discovery of vitamin C, the number of its known biological functions is continually expanding. Both the names ascorbic acid and vitamin C reflect its antiscorbutic properties due to its role in the synthesis of collagen in connective tissues. Ascorbate acts as an electron-donor keeping iron in the ferrous state thereby maintaining the full activity of collagen hydroxylases; parallel reactions with a variety of dioxygenases affect the expression of a wide array of genes, for example via the HIF system, as well as via the epigenetic landscape of cells and tissues. In fact, all known physiological and biochemical functions of ascorbate are due to its action as an electron donor. The ability to donate one or two electrons makes AscH(-) an excellent reducing agent and antioxidant. Ascorbate readily undergoes pH-dependent autoxidation producing hydrogen peroxide (H(2)O(2)). In the presence of catalytic metals this oxidation is accelerated. In this review, we show that the chemical and biochemical nature of ascorbate contribute to its antioxidant as well as its prooxidant properties. Recent pharmacokinetic data indicate that intravenous (i.v.) administration of ascorbate bypasses the tight control of the gut producing highly elevated plasma levels; ascorbate at very high levels can act as prodrug to deliver a significant flux of H(2)O(2) to tumors. This new knowledge has rekindled interest and spurred new research into the clinical potential of pharmacological ascorbate. Knowledge and understanding of the mechanisms of action of pharmacological ascorbate bring a rationale to its use to treat disease especially the use of i.v. delivery of pharmacological ascorbate as an adjuvant in the treatment of cancer.
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Affiliation(s)
- Juan Du
- Department of Radiation Oncology, University of Iowa College of Medicine, Iowa City, IA, USA
| | - Joseph J. Cullen
- Department of Radiation Oncology, University of Iowa College of Medicine, Iowa City, IA, USA
- Department of Surgery, University of Iowa College of Medicine, Iowa City, IA, USA
- Holden Comprehensive Cancer Center, USA
- Veterans Affairs Medical Center, Iowa City, IA, USA
| | - Garry R. Buettner
- Department of Radiation Oncology, University of Iowa College of Medicine, Iowa City, IA, USA
- Holden Comprehensive Cancer Center, USA
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8
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Dehydroascorbate protection against dioxin-induced toxicity in the beta-cell line INS-1E. Toxicol Lett 2009; 189:27-34. [PMID: 19414064 DOI: 10.1016/j.toxlet.2009.04.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Accepted: 04/27/2009] [Indexed: 11/22/2022]
Abstract
Oxidative stress has been proposed as a mechanism of the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The aim of this research was to evaluate the protective effects of increased intracellular ascorbate levels against TCDD acute toxicity in the insulin-secreting beta-cell line INS-1E. Ascorbate is considered a potent antioxidant, but its therapeutic efficacy is greatly limited by its slow achievement of high intracellular levels. This might be circumvented by administration of dehydroascorbate (DHA), which is transported at a much higher rate and undergoes rapid intracellular reduction to ascorbate. Indeed, 30 min incubation of INS-1E cells with various concentrations of DHA caused a remarkable, dose-related increase of the intracellular ascorbate levels. INS-1E cells preincubated with 0.5 and 1.0mM DHA showed a greater viability than control cells after 1h exposition to cytotoxic TCDD concentrations. In our experimental conditions, TCDD surprisingly failed to increase ROS production in INS-1E cells, but induced a dose-related mitochondrial depolarisation which was significantly improved by DHA preincubation. Furthermore, DHA preincubation completely prevented the low dose TCDD-induced inhibition of glucose-stimulated insulin secretion. Thus, our results suggest that DHA preincubation protects INS-1E cells against TCDD acute toxicity by partially preserving mitochondrial function.
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9
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Alper G, Olukman M, Irer S, Cağlayan O, Duman E, Yilmaz C, Ulker S. Effect of vitamin E and C supplementation combined with oral antidiabetic therapy on the endothelial dysfunction in the neonatally streptozotocin injected diabetic rat. Diabetes Metab Res Rev 2006; 22:190-7. [PMID: 16216038 DOI: 10.1002/dmrr.586] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND This study investigates the contribution of vitamin supplementation to the efficacy of oral antidiabetic therapy on the reversal of endothelial dysfunction in a model of type-2 diabetes in rat. METHODS Diabetes was induced by streptozotocin injection to neonatal rats which were breastfed for 4 weeks, then fed 6 weeks with normal food or food supplemented with 2% vitamin E and 4% vitamin C. Some diabetic rats were treated with gliclazide for 6 weeks. Endothelium-dependent and -independent relaxations to acetylcholine and sodium nitroprusside (SNP) were recorded in thoracic aortic rings. Plasma insulin, HbA(1c) and antioxidant vitamins (A, C and E); plasma and aortic malondialdehyde (MDA) levels were determined. RESULTS Induction of diabetes resulted in decreased body weight and increased blood glucose, plasma insulin and HbA(1c) levels compared to controls. Acetylcholine relaxation was impaired in diabetic aorta, while SNP relaxation remained unchanged. Aortic MDA level was significantly higher, while plasma vitamin levels were lower in diabetic rats. Diminished acetylcholine response, enhanced aortic MDA level and decreased plasma vitamin levels were all restored after gliclazide and/or vitamin therapy. However, vitamin supplementation in control rats significantly impaired acetylcholine relaxations and increased aortic MDA levels. CONCLUSIONS Apparently, a selective endothelial dysfunction accompanies the imbalance in oxidant/antioxidant status in the type-2 diabetes model of rat and gliclazide and/or vitamin supplementation improves the impairment in diabetic vasculature. However, vitamin supplementation triggers oxidative stress in normal aortic tissue, thereby, leads to endothelial dysfunction; indicating that nutritional extra-supplementation of antioxidant vitamins isn't advisable for normal subjects, although it's beneficial in disease status.
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Affiliation(s)
- Gülinnaz Alper
- Department of Biochemistry, Faculty of Medicine, Ege University, Izmir, Turkey.
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10
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Martinovich GG, Cherenkevich SN, Sauer H. Intracellular redox state: towards quantitative description. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2005; 34:937-42. [PMID: 16215752 DOI: 10.1007/s00249-005-0470-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2004] [Accepted: 01/28/2005] [Indexed: 02/04/2023]
Abstract
Redox state is a widely used term for the description of redox phenomena in biological systems. The regulating mechanisms responsible for maintaining the redox state are not yet fully known. But it was shown that changes in the redox state might lead to a cascade of intracellular events, beneficial or deleterious to the cell. There are several methods for the description of the intracellular redox state. These methods are based on using measured intracellular concentrations of reduced and oxidized glutathione in the Nernst equation. However, glutathione is not always a basic redox component in biological fluids, organelles, cells or tissues. As a result, changes in the intracellular redox state are not always accompanied by considerable changes of glutathione concentration. In this work it was proposed to use the concept of effective reduction potential for the quantitative characteristic of the intracellular redox state. The effective reduction potential was substantiated on the basis of a thermodynamic description. A new equation for the calculation of the effective reduction potential was derived. This equation summarizes the contribution of different oxidizing and reducing agents in the formation of an effective redox potential. The theoretical estimation of the effective reduction potential values for the different biological fluids and cells was carried out with the use of a method developed.
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Affiliation(s)
- Grigory G Martinovich
- Department of Biophysics, Belarus State University, Fr. Skorina Ave. 4, 220050 Minsk, Belarus.
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11
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Yamamoto F, Kaneshiro T, Kato H, Mukai T, Kuwabara Y, Honda H, Maeda M. Decreased Tissue Accumulation of 6-Deoxy-6-[18F]fluoro-L-ascorbic Acid in Glutathione-Deficient Rats Induced by Administration of Diethyl Maleate. Biol Pharm Bull 2005; 28:1943-7. [PMID: 16204951 DOI: 10.1248/bpb.28.1943] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The relationship between in vivo biodistribution of 6-deoxy-6-[18F]fluoro-L-ascorbic acid (18F-DFA) and the content of tissue glutathione (GSH) was investigated in Wistar male rats. Following intravenous administration of 18F-DFA, the accumulation of radioactivity in most tissues, including the adrenal glands, liver and brain, was significantly reduced together with a decrease in the content of GSH by preloading of diethyl maleate (DEM) which depletes cellular GSH. Similar decreased uptake was also observed in the distribution of L-[1-14C]ascorbic acid (14C-AA) after DEM treatment. The possible biological mechanisms, including competition with endogenous AA and ascorbate recycling, that modulate the uptake and accumulation into tissues of 18F-DFA and 14C-AA in GSH-deficient rats are discussed.
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Affiliation(s)
- Fumihiko Yamamoto
- Faculty of Pharmaceutical Sciences, Kyushu University; Fukuoka 812-8582, Japan
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