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Showing papers on "Ascorbic acid published in 2014"


Journal ArticleDOI
TL;DR: This review focuses on the different types of ROS, their cellular production sites, their targets, and their scavenging mechanism mediated by both the branches of the antioxidant systems, highlighting the potential role of antioxidant in plants.
Abstract: Reactive oxygen species (ROS) were initially recognized as toxic by-products of aerobic metabolism. In recent years, it has become apparent that ROS plays an important signaling role in plants, controlling processes such as growth, development and especially response to biotic and abiotic environmental stimuli. The major members of the ROS family include free radicals like O2● −, OH● and non-radicals like H2O2 and 1O2. The ROS production in plants is mainly localized in the chloroplast, mitochondria and peroxisomes. There are secondary sites as well like the endoplasmic reticulum, cell membrane, cell wall and the apoplast. The role of the ROS family is that of a double edged sword; while they act as secondary messengers in various key physiological phenomena, they also induce oxidative damages under several environmental stress conditions like salinity, drought, cold, heavy metals, UV irradiation etc., when the delicate balance between ROS production and elimination, necessary for normal cellular homeostasis, is disturbed. The cellular damages are manifested in the form of degradation of biomolecules like pigments, proteins, lipids, carbohydrates and DNA, which ultimately amalgamate in plant cellular death. To ensure survival, plants have developed efficient antioxidant machinery having two arms, (i) enzymatic components like superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR); (ii) non-enzymatic antioxidants like ascorbic acid (AA), reduced glutathione (GSH), α-tocopherol, carotenoids, flavonoids and the osmolyte proline. These two components work hand in hand to scavenge ROS. In this review, we emphasize on the different types of ROS, their cellular production sites, their targets, and their scavenging mechanism mediated by both the branches of the antioxidant systems, highlighting the potential role of antioxidant

1,954 citations


Journal ArticleDOI
TL;DR: Intravenous ascorbic acid infusion was safe and well tolerated in this study and may positively impact the extent of multiple organ failure and biomarkers of inflammation and endothelial injury.
Abstract: Parenterally administered ascorbic acid modulates sepsis-induced inflammation and coagulation in experimental animal models. The objective of this randomized, double-blind, placebo-controlled, phase I trial was to determine the safety of intravenously infused ascorbic acid in patients with severe sepsis. Twenty-four patients with severe sepsis in the medical intensive care unit were randomized 1:1:1 to receive intravenous infusions every six hours for four days of ascorbic acid: Lo-AscA (50 mg/kg/24 h, n = 8), or Hi-AscA (200 mg/kg/24 h, n = 8), or Placebo (5% dextrose/water, n = 8). The primary end points were ascorbic acid safety and tolerability, assessed as treatment-related adverse-event frequency and severity. Patients were monitored for worsened arterial hypotension, tachycardia, hypernatremia, and nausea or vomiting. In addition Sequential Organ Failure Assessment (SOFA) scores and plasma levels of ascorbic acid, C-reactive protein, procalcitonin, and thrombomodulin were monitored. Mean plasma ascorbic acid levels at entry for the entire cohort were 17.9 ± 2.4 μM (normal range 50-70 μM). Ascorbic acid infusion rapidly and significantly increased plasma ascorbic acid levels. No adverse safety events were observed in ascorbic acid-infused patients. Patients receiving ascorbic acid exhibited prompt reductions in SOFA scores while placebo patients exhibited no such reduction. Ascorbic acid significantly reduced the proinflammatory biomarkers C-reactive protein and procalcitonin. Unlike placebo patients, thrombomodulin in ascorbic acid infused patients exhibited no significant rise, suggesting attenuation of vascular endothelial injury. Intravenous ascorbic acid infusion was safe and well tolerated in this study and may positively impact the extent of multiple organ failure and biomarkers of inflammation and endothelial injury. ClinicalTrials.gov identifier NCT01434121 .

433 citations


Journal ArticleDOI
TL;DR: In this paper, a facile electrochemical method was applied to prepare electrochemically reduced graphene oxide (ERGO), and the morphology and structure of ERGO were characterized by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectrography and Xray diffraction (XRD).
Abstract: A facile electrochemical method was applied to prepare electrochemically reduced graphene oxide (ERGO). The morphology and structure of ERGO were characterized by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and X-ray diffraction (XRD). Compared with the bare glassy carbon electrode (GCE), ERGO modified GCE (ERGO/GCE) exhibits much higher electrocatalytic activities toward the oxidation of dopamine (DA), ascorbic acid (AA) and uric acid (UA) with increasing of peak currents and decreasing of oxidation overpotentials. Differential pulse voltammetry results show that DA, AA and UA could be detected selectively and sensitively at ERGO/GCE with peak-to-peak separation of 240 mV and 130 mV for AA–DA and DA–UA, respectively. The linear ranges for AA, UA and DA are 500–2000 μM, 0.5–60 μM and 0.5–60 μM, respectively. Meanwhile, due to the negligible response to physiological level of AA (0.1 mM), ERGO/GCE could be used for the determination of DA in biological sample with high sensitivity and good selectivity. In addition, the presented method was successfully applied for the simultaneous determination of DA, AA and UA in urine sample with reliable recovery. This work provides a simple and green route to construct graphene-based electrochemical sensor, which is promising for the simultaneous determination of DA, AA and UA.

392 citations


Journal ArticleDOI
TL;DR: A facile Au nanoplates and reduced graphene oxide (RGO) modified glassy carbon electrode (GCE) was fabricated via a simple electrochemical method, denoted as Au/RGO/GCE.
Abstract: A facile Au nanoplates and reduced graphene oxide (RGO) modified glassy carbon electrode (GCE) was fabricated via a simple electrochemical method, denoted as Au/RGO/GCE. The Au/RGO/GCE electrode was used for the simultaneous detection of ascorbic acid (AA), dopamine (DA) and uric acid (UA). The modified electrodes fabricated by different methods presented different morphologies and performances for determination of AA, DA, and UA. Three well-defined voltammetric peaks along with remarkable increasing electrooxidation currents were obtained on the Au/RGO/GCE with needle-like Au nanoplates in differential pulse voltammetry (DPV) measurements. It was found that there are linear relationships between the peak currents and the concentrations in the range of 2.4 × 10 −4 to 1.5 × 10 −3 M (AA), 6.8 × 10 −6 to 4.1 × 10 −5 M (DA), and 8.8 × 10 −6 to 5.3 × 10 −5 M (UA), and the limits of simultaneous determination (based on S/N = 3) are 5.1 × 10 −5 M, 1.4 × 10 −6 M, and 1.8 × 10 −6 M for AA, DA and UA, respectively. Additionally, the Au/RGO/GCE electrode presented well anti-interference ability, stability and reproducibility.

375 citations


30 Jan 2014
TL;DR: The chemical composition, identify the bioactive compounds and measure the antioxidant activity present in blackberry, red raspberry, strawberry, sweet cherry and blueberry fruits produced in the subtropical areas of Brazil are evaluated to verify that the chemical properties of these fruit are similar when compared to the temperate production zones.
Abstract: This study aimed to evaluate the chemical composition, identify the bioactive compounds and measure the antioxidant activity present in blackberry, red raspberry, strawberry, sweet cherry and blueberry fruits produced in the subtropical areas of Brazil and to verify that the chemical properties of these fruit are similar when compared to the temperate production zones. Compared with berries and cherries grown in temperate climates, the centesimal composition and physical chemical characteristics found in the Brazilian berries and cherries are in agreement with data from the literature. For the mineral composition, the analyzed fruits presented lower concentrations of P, K, Ca, Mg and Zn and higher levels of Fe. The values found for the bioactive compounds generally fit the ranges reported in the literature with minor differences. The greatest difference was found in relation to ascorbic acid, as all fruits analyzed showed levels well above those found in the literature.

335 citations


Journal ArticleDOI
TL;DR: In this paper, the authors evaluate the chemical composition, identify the bioactive compounds and measure the antioxidant activity present in blackberry, red raspberry, strawberry, sweet cherry and blueberry fruits produced in the subtropical areas of Brazil and verify that the chemical properties of these fruit are similar when compared to the temperate production zones.

332 citations


Journal ArticleDOI
TL;DR: Green synthesized TiO2 NPs provides a promising approach can satisfy the requirement of large-scale industrial production bearing the advantage of low-cost, eco-friendly and reproducible.

328 citations


Journal ArticleDOI
Wenchao Duan1, Zhiqiang Zhu1, Hao Li1, Zhe Hu1, Kai Zhang1, Fangyi Cheng1, Jun Chen1 
TL;DR: In this paper, a NVP@C core-shell nanocomposite has been synthesized through a hydrothermal assisted sol-gel method, where ascorbic acid and polyethylene glycol 400 (PEG-400) were synergistically used to control the particle growth and provide the surface coating of conductive carbon.
Abstract: Na3V2(PO4)3 (NVP) is an attractive cathode material for sodium ion batteries due to its high theoretical energy density and stable three-dimensional (3D) NASICON structure. In this paper, a NVP@C core–shell nanocomposite has been synthesized through a hydrothermal assisted sol–gel method. Ascorbic acid and polyethylene glycol 400 (PEG-400) were synergistically used to control the particle growth and provide the surface coating of conductive carbon. The as-prepared nanocomposite was composed of a nanosized Na3V2(PO4)3 core with a typical size of ∼40 nm and a uniformly amorphous carbon shell with the thickness of a few nanometers. The electrode performance of the NVP@C core–shell nanocomposite as cathode for sodium ion batteries is investigated and compared with that of bare NVP and NVP/C. Among the samples examined, the NVP@C nanocomposite showed the best cycle life and rate capability. It rendered an initial capacity of 104.3 mA h g−1 at 0.5 C and 94.9 mA h g−1 at 5 C with a remarkable capacity retention of 96.1% after 700 cycles. Moreover, a full cell using the as-prepared nanocomposite as both the cathode and the anode active material has been successfully built, showing a reversible capacity of 90.9 mA h g−1 at 2 C with an output voltage of about 1.7 V and a specific energy density of about 154.5 W h kg−1. The enhanced electrode performance is attributed to the combination of particle downsizing and carbon coating, which can favor the migration of both electrons and ions.

323 citations


Journal ArticleDOI
TL;DR: Two iron(III)-based metal-organic frameworks are found to behave as efficient peroxidase mimics and catalyze the oxidation of different peroxIDase substrates by H2O2 accompanied with significant color change in the solution.

316 citations


Journal ArticleDOI
Wanying Zhai1, Chunxia Wang1, Ping Yu1, Yuexiang Wang1, Lanqun Mao1 
TL;DR: The turn-on fluorescence method demonstrated here can be used for in vivo sensing of AA in a simple but reliable way and possesses a higher sensitivity, lower limit of detection, and wider linear range.
Abstract: In this study, we systematically investigate the mechanism of single-layer MnO2 nanosheets suppressing fluorescence of 7-hydroxycoumarin and, based on this, demonstrate a new fluorescent method for in vivo sensing of ascorbic acid (AA) in rat brain. The mechanism for the fluorescence suppression is attributed to a combination of inner filter effect (IFE) and static quenching effect (SQE), which is different from those reported for the traditional two-dimensional nanosheets, and Forster resonant energy transfer (FRET) mechanism reported for MnO2 nanosheets. The combination of IFE and SQE leads to an exponential decay in fluorescence intensity of 7-hydroxycoumarin with increasing concentration of MnO2 nanosheets in solution. Such a property allows optimization of the concentration of MnO2 nanosheets in such a way that the addition of reductive analyte (e.g., AA) will to the greatest extent restore the MnO2 nanosheets-suppressed fluorescence of 7-hydroxycoumarin through the redox reaction between AA and MnO2 nanosheets. On the basis of this feature, we demonstrate a fluorescent method for in vivo sensing of AA in the cerebral systems with an improved sensitivity. Compared with the turn-on fluorescent method through first decreasing the fluorescence to the lowest level by adding concentrated MnO2 nanosheets, the method demonstrated here possesses a higher sensitivity, lower limit of detection, and wider linear range. Upon the use of ascorbate oxidase to achieve the selectivity for AA, the turn-on fluorescence method demonstrated here can be used for in vivo sensing of AA in a simple but reliable way.

308 citations


Journal ArticleDOI
TL;DR: Enzyme-free (also called nonenzymatic or direct) electrochemical sensors have been widely used for the determination of hydrogen peroxide, glucose, and uric acid as mentioned in this paper.
Abstract: Enzyme-free (also called non-enzymatic or direct) electrochemical sensors have been widely used for the determination of hydrogen peroxide, glucose, and uric acid. This review covers the recent progress made in this field. We also discuss the respective sensor materials which have strong effect on the electro-catalytic properties of the electrodes and govern the performance of these sensors. In addition, perspectives and current challenges of enzyme-free electrochemical sensors are outlined. Contains 142 references.

Journal ArticleDOI
TL;DR: Strawberries consumption improves plasma lipids profile, biomarkers of antioxidant status, antihemolytic defenses and platelet function in healthy subjects, encouraging further evaluation on a population with higher cardiovascular disease risk.
Abstract: Strawberries are an important fruit in the Mediterranean diet because of their high content of essential nutrients and beneficial phytochemicals, which seem to exert beneficial effects in human health. Healthy volunteers were supplemented daily with 500 g of strawberries for 1 month. Plasma lipid profile, circulating and cellular markers of antioxidant status, oxidative stress and platelet function were evaluated at baseline, after 30 days of strawberry consumption and 15 days after the end of the study. A high concentration of vitamin C and anthocyanins was found in the fruits. Strawberry consumption beneficially influenced the lipid profile by significantly reducing total cholesterol, low-density lipoprotein cholesterol and triglycerides levels (−8.78%, −13.72% and −20.80%, respectively; P P P P P

Journal ArticleDOI
TL;DR: The modified biosensor was applied to the determination of AA, DA, UA and NO2(-) in urine samples by using standard adding method with satisfactory results.

Journal ArticleDOI
TL;DR: Silver and copper nanoparticles were produced by chemical reduction of their respective nitrates by ascorbic acid in the presence of chitosan using microwave heating and particle size was shown to increase by increasing the concentration of nitrate and reducing the chitOSan concentration.

Journal ArticleDOI
13 Jan 2014-ACS Nano
TL;DR: In this paper, vertically aligned ZnO nanowire arrays (ZnO NWAs) were fabricated on 3D graphene foam (GF) and used to selectively detect uric acid (UA), dopamine (DA), and ascorbic acid(AA) by a differential pulse voltammetry method.
Abstract: We report that vertically aligned ZnO nanowire arrays (ZnO NWAs) were fabricated on 3D graphene foam (GF) and used to selectively detect uric acid (UA), dopamine (DA), and ascorbic acid (AA) by a differential pulse voltammetry method. The optimized ZnO NWA/GF electrode provided a high surface area and high selectivity with a detection limit of 1 nM for UA and DA. The high selectivity in the oxidation potential was explained by the gap difference between the lowest unoccupied and highest occupied molecular orbitals of a biomolecule for a set of given electrodes. This method was further used to detect UA levels in the serum of patients with Parkinson’s disease (PD). The UA level was 25% lower in PD patients than in healthy individuals. This finding strongly implies that UA can be used as a biomarker for PD.

Journal ArticleDOI
TL;DR: The antioxidant features together with the high polyphenolic contents can support at least in part, the usage of the peel extracts as nutraceutical supplements, especially to be used as anti-ageing products.
Abstract: Peels and edible pulp from three species of citrus including Citrus aurantifolia (varieties pica and sutil) and Citrus x lemon var. Genova widely cultivated and consumed in Northern Chile (I and II region) were analyzed for phenolic compounds and antioxidant activity for the first time. A high performance electrospray ionization mass spectrometry (HPLC-UV-ESI-MS) method was developed for the rapid identification of phenolics in extracts from peels and juices of all species. Several flavonoids including one kaempferol-O-hexoside (peak 16) and one hesperidin derivative (peak 22) three quercetin derivatives (peaks 4, 19 and 36), five isorhamnetin derivatives (peaks 5, 23, 24, 26 and 29) four luteolin derivatives (peaks 14, 25, 27 and 40), seven apigenin derivatives (peaks 2, 3, 12, 20, 34, 35 and 39), seven diosmetin derivatives (peaks 7-9, 17, 21, 31 and 37), three chrysoeriol derivatives (peaks 10, 18 and 30), and four eryodictiol derivatives (peaks 6, 13, 15 and 38) were identified in negative and positive mode using full scan mass measurements and MSn fragmentations. Ascorbic acid content was higher in the pulps of the varieties Genova and Sutil (60.13 ± 1.28 and 56.53 ± 1.06 mg ascorbic acid per g dry weight, respectively) while total phenolic content was higher in Pica peels followed by Sutil peels (34.59 ± 0.81 and 25.58 ± 1.02 mg/g GAE dry weight, respectively). The antioxidant capacity was also higher for Pica peels (10.34 ± 1.23 µg/mL in the DPPH assay and 120.63 ± 2.45 µM trolox equivalents/g dry weight in the FRAP assay). The antioxidant features together with the high polyphenolic contents can support at least in part, the usage of the peel extracts as nutraceutical supplements, especially to be used as anti-ageing products.

Journal ArticleDOI
TL;DR: A novel biosensor can measure the H2O2 release from living cells because of its low detection limit, wide linear range, and higher sensitivity.
Abstract: A sensitive hydrogen peroxide (H2O2) sensor was constructed based on graphene-Pt (RGO-Pt) nanocomposites and used to measure the release of H2O2 from living cells. The graphene and Pt nanoparticles (Pt NPs) were modified on glassy carbon electrode (GCE) by the physical adsorption and electrodeposition of K2PtCl6 solution, respectively. Through characterization by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), it was observed that the electrodeposited Pt NPs were densely covered and well distributed on the entire graphene surface. Electrochemical study demonstrates that the RGO-Pt nanocomposites modified glassy carbon electrode exhibited a high peak current and low overpotential toward the reduction of H2O2. The relevant detection limit of H2O2 is ∼0.2 μM with a wide linear range from 0.5 μM to 3.475 mM, displaying a much higher sensitivity (459 ± 3 mA M(-1) cm(-2), n = 5) than that of Pt nanoparticles or graphene modified electrode. This novel biosensor can measure the H2O2 release from living cells because of its low detection limit, wide linear range, and higher sensitivity.

Journal ArticleDOI
TL;DR: A novel and sensitive carbon fiber electrode modified by graphene flowers was prepared and used to simultaneously determine ascorbic acid, dopamine and uric acid and showed satisfactory results when applied to the determination of AA, DA and UA in urine and serum samples.

Journal ArticleDOI
TL;DR: No clear evidence of a benefit associated with nutritional interventions for either the prevention or treatment of pressure ulcers is found and further trials of high methodological quality are necessary.
Abstract: Background Pressure ulcers affect approximately 10% of people in hospitals and older people are at highest risk A correlation between inadequate nutritional intake and the development of pressure ulcers has been suggested by several studies, but the results have been inconsistent Objectives To evaluate the effects of enteral and parenteral nutrition on the prevention and treatment of pressure ulcers Search methods In March 2014, for this first update, we searched The Cochrane Wounds Group Specialised Trials Register, the Cochrane Central register of Controlled Trials (The Cochrane Library), the Database of Abstracts of Reviews of Effects (DARE) (The Cochrane Library), the Health Technology Assessment Database (HTA) (The Cochrane Library), the Cochrane Methodology Register (The Cochrane Library), NHS Economic Evaluation Database (The Cochrane Library), Ovid Medline, Ovid Embase and EBSCO CINAHL No date, language or publication status limits were applied Selection criteria Randomised controlled trials (RCTs) evaluating the effects of enteral or parenteral nutrition on the prevention and treatment of pressure ulcers, which measured the incidence of new ulcers, ulcer healing or changes in pressure ulcer severity There were no restrictions on types of patient, setting, date, publication status or language Data collection and analysis Two review authors independently screened for inclusion, and disagreement was resolved by discussion Two review authors independently extracted data and assessed quality using the Cochrane Collaboration tool for assessing risk of bias Main results We included 23 RCTs, many were small (between 9 and 4023 participants, median 88) and at high risk of bias Eleven trials compared a combination of nutritional supplements, consisting of a minimum of energy and protein in different dosages, for the prevention of pressure ulcers A meta-analysis of eight trials (6062 participants) that compared the effects of mixed nutritional supplements with standard hospital diet found no clear evidence of an effect of supplementation on pressure ulcer development (pooled RR 086; 95% CI 073 to 100; P value 005; I2 = 13%, random effects) This outcome is at unclear or high risk of bias Fourteen trials evaluated the effects of nutritional supplements on the healing of existing pressure ulcers: seven trials examined mixed nutritional supplements, three the effects of proteins, two trials examined zinc, and two studies examined ascorbic acid The included trials were heterogeneous with regard to participants, interventions, comparisons and outcomes and meta-analysis was not appropriate There was no clear evidence of an improvement in pressure ulcer healing from the nutritional supplements evaluated in any of these individual studies Authors' conclusions There is currently no clear evidence of a benefit associated with nutritional interventions for either the prevention or treatment of pressure ulcers Further trials of high methodological quality are necessary

Journal ArticleDOI
TL;DR: In this article, three a-cellular assays; dithiothreitol (OPDTT), electron spin resonance (OPESR), and ascorbate depletion (OPAA) were used to characterize the oxidative potential (OP) of PM.

Journal ArticleDOI
TL;DR: The role of vitamin C in mitigating oxidative injury-induced microcirculatory impairment and associated organ failure in ischemia/reperfusion or sepsis, and promoting recovery after cardiac revascularization and in critically ill patients is summarized.
Abstract: This narrative review summarizes the role of vitamin C in mitigating oxidative injury-induced microcirculatory impairment and associated organ failure in ischemia/reperfusion or sepsis Preclinical studies show that high-dose vitamin C can prevent or restore microcirculatory flow impairment by inhibiting activation of nicotinamide adenine dinucleotide phosphate-oxidase and inducible nitric oxide synthase, augmenting tetrahydrobiopterin, preventing uncoupling of oxidative phosphorylation, and decreasing the formation of superoxide and peroxynitrite, and by directly scavenging superoxide Vitamin C can additionally restore vascular responsiveness to vasoconstrictors, preserve endothelial barrier by maintaining cyclic guanylate phosphatase and occludin phosphorylation and preventing apoptosis Finally, high-dose vitamin C can augment antibacterial defense These protective effects against overwhelming oxidative stress due to ischemia/reperfusion, sepsis or burn seems to mitigate organ injury and dysfunction, and promote recovery after cardiac revascularization and in critically ill patients, in the latter partially in combination with other antioxidants Of note, several questions remain to be solved, including optimal dose, timing and combination of vitamin C with other antioxidants The combination obviously offers a synergistic effect and seems reasonable during sustained critical illness High-dose vitamin C, however, provides a cheap, strong and multifaceted antioxidant, especially robust for resuscitation of the circulation Vitamin C given as early as possible after the injurious event, or before if feasible, seems most effective The latter could be considered at the start of cardiac surgery, organ transplant or major gastrointestinal surgery Preoperative supplementation should consider the inhibiting effect of vitamin C on ischemic preconditioning In critically ill patients, future research should focus on the use of short-term high-dose intravenous vitamin C as a resuscitation drug, to intervene as early as possible in the oxidant cascade in order to optimize macrocirculation and microcirculation and limit cellular injury

Journal ArticleDOI
01 Mar 2014-Leukemia
TL;DR: It is demonstrated that Tet2 functions as a tumor suppressor whose haploinsufficiency initiates myeloid and lymphoid transformations and how this knowledge influences therapeutic approaches in hematological malignancies and possibly other tumor types is discussed.
Abstract: Ten-Eleven Translocation-2 (TET2) inactivation through loss-of-function mutation, deletion and IDH1/2 (Isocitrate Dehydrogenase 1 and 2) gene mutation is a common event in myeloid and lymphoid malignancies. TET2 gene mutations similar to those observed in myeloid and lymphoid malignancies also accumulate with age in otherwise healthy subjects with clonal hematopoiesis. TET2 is one of the three proteins of the TET (Ten-Eleven Translocation) family, which are evolutionarily conserved dioxygenases that catalyze the conversion of 5-methyl-cytosine (5-mC) to 5-hydroxymethyl-cytosine (5-hmC) and promote DNA demethylation. TET dioxygenases require 2-oxoglutarate, oxygen and Fe(II) for their activity, which is enhanced in the presence of ascorbic acid. TET2 is the most expressed TET gene in the hematopoietic tissue, especially in hematopoietic stem cells. In addition to their hydroxylase activity, TET proteins recruit the O-linked β-D-N-acetylglucosamine (O-GlcNAc) transferase (OGT) enzyme to chromatin, which promotes post-transcriptional modifications of histones and facilitates gene expression. The TET2 level is regulated by interaction with IDAX, originating from TET2 gene fission during evolution, and by the microRNA miR-22. TET2 has pleiotropic roles during hematopoiesis, including stem-cell self-renewal, lineage commitment and terminal differentiation of monocytes. Analysis of Tet2 knockout mice, which are viable and fertile, demonstrated that Tet2 functions as a tumor suppressor whose haploinsufficiency initiates myeloid and lymphoid transformations. This review summarizes the recently identified TET2 physiological and pathological functions and discusses how this knowledge influences our therapeutic approaches in hematological malignancies and possibly other tumor types.

Journal ArticleDOI
TL;DR: In this article, a review of electrochemical methods for ascorbic acid assessment is presented, focusing on electrochemical sensors for assessing the concentration of vitamin C in various media.

Journal ArticleDOI
TL;DR: This review focuses on how ROS production is correlated with host cell death, and may play an important role as a signal molecule in the regulation of viral replication and organelle function, potentially providing new insights in the prevention and treatment of RNA viruses and retrovirus infections.
Abstract: Reactive oxygen species (ROS) are well known for being both beneficial and deleterious. The main thrust of this review is to investigate the role of ROS in ribonucleic acid (RNA) virus pathogenesis. Much evidences has accumulated over the past decade, suggesting that patients infected with RNA viruses are under chronic oxidative stress. Changes to the body's antioxidant defense system, in relation to SOD, ascorbic acid, selenium, carotenoids, and glutathione, have been reported in various tissues of RNA-virus infected patients. This review focuses on RNA viruses and retroviruses, giving particular attention to the human influenza virus, Hepatitis c virus (HCV), human immunodeficiency virus (HIV), and the aquatic Betanodavirus. Oxidative stress via RNA virus infections can contribute to several aspects of viral disease pathogenesis including apoptosis, loss of immune function, viral replication, inflammatory response, and loss of body weight. We focus on how ROS production is correlated with host cell death. Moreover, ROS may play an important role as a signal molecule in the regulation of viral replication and organelle function, potentially providing new insights in the prevention and treatment of RNA viruses and retrovirus infections.

Journal ArticleDOI
01 Jan 2014
TL;DR: In this paper, the thermal stability, antioxidant activity, and ultraviolet C light (UV-C) stability of standard polyphenols solutions (catechin, gallic acid, and vanillic acid) and of vegetal extracts from spruce bark and grape seeds were investigated.
Abstract: The thermal stability (60°C, 80°C, 100°C), antioxidant activity, and ultraviolet C light (UV-C) stability of standard polyphenols solutions (catechin, gallic acid, and vanillic acid) and of vegetal extracts from spruce bark and grape seeds were investigated. Exposure of the standard solutions and vegetal extracts to high temperatures revealed that phenolic compounds were also relatively stable (degradations ranged from 15 % to 30 % after 4 h of exposure). The highest antioxidant activity was obtained for ascorbic acid and gallic acid followed by catechin and caffeic acid and the grape seeds. The results show that, after 3 h of UV-C exposure, approximately 40 % of vanillic acid, 50 % of gallic acid, and 83 % of catechin were removed. Similar degradation rates were observed for vegetal extracts, with the exception of the degradation of catechin (40 %) from grape seeds. In addition, the photo-oxidation of polyphenols in the presence of food constituents such as citric acid, ascorbic acid, sodium chloride, and sodium nitrate was assessed.

Journal ArticleDOI
TL;DR: In this paper, a non-enzymatic glucose sensor based on Copper Oxide Nanowires (Copper oxide nanowires) is presented. But the performance of the sensor was not evaluated.
Abstract: Copper oxide nanowires (CuO NWs) were prepared by a facile two-step procedure consisting of wet-chemistry synthesis and subsequent direct calcination. The morphology, surface property, and crystal structure of the as-prepared CuO NWs were characterized by SEM, TEM, and XRD. The CuO NWs were further employed to construct a non-enzymatic glucose sensor with excellent performance toward glucose detection in 50 mM NaOH solution. The as-developed non-enzymatic glucose sensor showed a fast response time (less than 5 s) and a wide dynamic range with excellent sensitivity of 648.2 μA cm −2 mM −1 and 119.9 μA cm −2 mM −1 toward glucose detection at an applied potential of +0.55 V and +0.3 V (vs. Ag/AgCl), respectively. The Langmuir isothermal theory was employed to fit the obtained calibration curves with high correlation coefficient and the mechanisms for the glucose oxidation promoted by CuO NWs were also discussed. The good selectivity of the CuO NWs based non-enzymatic glucose sensor against electroactive compounds such as ascorbic acid, uric acid, and acetaminophen, and other sugars such as fructose and sucrose at their physiological concentrations were also demonstrated. Furthermore, good accuracy and high precision for the quantification of glucose concentration in human serum samples was attested. These good features indicate that CuO NWs have a great potential in the development of sensitive and selective non-enzymatic glucose sensor.

Journal ArticleDOI
TL;DR: The antioxidant content and nutritional value of purslane are important for human consumption and it revealed tremendous nutritional potential and has indicated the potential use of this herb for the future.
Abstract: Purslane (Portulaca oleracea L.) is an important plant naturally found as a weed in field crops and lawns. Purslane is widely distributed around the globe and is popular as a potherb in many areas of Europe, Asia, and the Mediterranean region. This plant possesses mucilaginous substances which are of medicinal importance. It is a rich source of potassium (494 mg/100 g) followed by magnesium (68 mg/100 g) and calcium (65 mg/100 g) and possesses the potential to be used as vegetable source of omega-3 fatty acid. It is very good source of alpha-linolenic acid (ALA) and gamma-linolenic acid (LNA, 18 : 3 w3) (4 mg/g fresh weight) of any green leafy vegetable. It contained the highest amount (22.2 mg and 130 mg per 100 g of fresh and dry weight, resp.) of alpha-tocopherol and ascorbic acid (26.6 mg and 506 mg per 100 g of fresh and dry weight, resp.). The oxalate content of purslane leaves was reported as 671–869 mg/100 g fresh weight. The antioxidant content and nutritional value of purslane are important for human consumption. It revealed tremendous nutritional potential and has indicated the potential use of this herb for the future.

Journal ArticleDOI
TL;DR: Skin cells are constantly exposed to reactive oxygen species (ROS) and oxidative stress from exogenous and endogenous sources and the only endogenous protection of the authors' skin is melanin and enzymatic antioxidants.
Abstract: Skin cells are constantly exposed to reactive oxygen species (ROS) and oxidative stress from exogenous and endogenous sources. UV radiation is the most important environmental factor in the development of skin cancer and skin aging. The primary products caused by UV exposure are generally direct DNA oxidation or generation of free radicals which form and decompose extremely quickly but can produce effects that can last for hours, days, or even years. UV-induced generation of ROS in the skin develops oxidative stress when their formation exceeds the antioxidant defense ability. The reduction of oxidative stress can be achieved on two levels: by lowering exposure to UVR and/or by increasing levels of antioxidant defense in order to scavenge ROS. The only endogenous protection of our skin is melanin and enzymatic antioxidants. Melanin, the pigment deposited by melanocytes, is the first line of defense against DNA damage at the surface of the skin, but it cannot totally prevent skin damage. A second category of defense is repair processes, which remove the damaged biomolecules before they can accumulate and before their presence results in altered cell metabolism. Additional UV protection includes avoidance of sun exposure, usage of sunscreens, protective clothes, and antioxidant supplements.

Journal ArticleDOI
TL;DR: In this article, a Pt/reduced graphene oxide (Pt/RGO) modified glassy carbon electrode was prepared for the detection of dopamine (DA) and uric acid (UA) in the presence of high concentration of ascorbic acid.

Journal Article
TL;DR: In this paper, Antioxidant activity was performed by DPPH (1, 1diphenyl-2-picryl hydrazyl) radical scavenging method for different extracts of aerial parts like leaves and flowers of Ageratum conyzoides Linn.
Abstract: In this study Antioxidant activity was performed by DPPH (1, 1diphenyl-2-picryl hydrazyl) radical scavenging method for different extracts of aerial parts like leaves and flowers of Ageratum conyzoides Linn. plant species which showed that alcoholic extract of leaves of this plant on higher concentration possess better antioxidant potential when compare to reference standard ascorbic acid. They exhibited strong antioxidant DPPH radical scavenging activity with IC50 value of 9.3 and 24.8 µg/ml for ascorbic acid and alcoholic leaves extract respectively. The absorbance for reducing power was found to be 0.0390, 0.0989 for ascorbic acid and alcoholic leaves extract respectively. The strongest antioxidant activity of ethanol extract could be due to the presence of flavonoids and phenols.