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Sample records for ascorbate synthesizing enzyme

  1. Aortic wall damage in mice unable to synthesize ascorbic acid.

    Science.gov (United States)

    Maeda, N; Hagihara, H; Nakata, Y; Hiller, S; Wilder, J; Reddick, R

    2000-01-18

    By inactivating the gene for L-gulono-gamma-lactone oxidase, a key enzyme in ascorbic acid synthesis, we have generated mice that, like humans, depend on dietary vitamin C. Regular chow, containing about 110 mg/kg of vitamin C, is unable to support the growth of the mutant mice, which require L-ascorbic acid supplemented in their drinking water (330 mg/liter). Upon withdrawal of supplementation, plasma and tissue ascorbic acid levels decreased to 10-15% of normal within 2 weeks, and after 5 weeks the mutants became anemic, began to lose weight, and die. Plasma total antioxidative capacities were approximately 37% normal in homozygotes after feeding the unsupplemented diet for 3-5 weeks. As plasma ascorbic acid decreased, small, but significant, increases in total cholesterol and decreases in high density lipoprotein cholesterol were observed. The most striking effects of the marginal dietary vitamin C were alterations in the wall of aorta, evidenced by the disruption of elastic laminae, smooth muscle cell proliferation, and focal endothelial desquamation of the luminal surface. Thus, marginal vitamin C deficiency affects the vascular integrity of mice unable to synthesize ascorbic acid, with potentially profound effects on the pathogenesis of vascular diseases. Breeding the vitamin C-dependent mice with mice carrying defined genetic mutations will provide numerous opportunities for systematic studies of the role of antioxidants in health and disease.

  2. Aortic wall damage in mice unable to synthesize ascorbic acid

    OpenAIRE

    Maeda, Nobuyo; Hagihara, Hiroyuki; Nakata, Yukiko; Hiller, Sylvia; Wilder, Jennifer; Reddick, Robert

    2000-01-01

    By inactivating the gene for l-gulono-γ-lactone oxidase, a key enzyme in ascorbic acid synthesis, we have generated mice that, like humans, depend on dietary vitamin C. Regular chow, containing about 110 mg/kg of vitamin C, is unable to support the growth of the mutant mice, which require l-ascorbic acid supplemented in their drinking water (330 mg/liter). Upon withdrawal of supplementation, plasma and tissue ascorbic acid levels decreased to 10–15% of normal within 2 weeks, and after 5 weeks...

  3. Influence of enzymes and ascorbic acid on dough rheology and ...

    African Journals Online (AJOL)

    Influence of enzymes and ascorbic acid on dough rheology and wheat bread quality. ... Journal Home > Vol 15, No 3 (2016) >. Log in or ... Seven bread formulations containing different concentrations of these ... The rheological properties of each dough formulation were determined by moisture, gluten and farinograph tests.

  4. Use of equimolar cysteine/ascorbic acids to recover MCP synthesized Ti(Mg) alloy

    CSIR Research Space (South Africa)

    Mushove, T

    2010-10-01

    Full Text Available Dissolution of waste by-products of mechanochemical processing (MCP) synthesis of Ti(Mg) alloy, from TiO2 and 15 wt.% excess Mg, was conducted in equimolar cysteine/ascorbic acids. The synthesized alloy is inherently mixed with MgO and other oxides...

  5. Influence of enzymes and ascorbic acid on dough rheology and ...

    African Journals Online (AJOL)

    The combined action of ascorbic acid and two commercial enzymatic complexes containing amylase and xylanase/amylase was analyzed to determine their effects on dough rheology and bread quality. Seven bread formulations containing different concentrations of these improvers were used in the analysis.

  6. Proteomic and activity profiles of ascorbate-glutathione cycle enzymes in germinating barley embryo

    DEFF Research Database (Denmark)

    Bønsager, Birgit Christine; Shahpiri, Azar; Finnie, Christine

    2010-01-01

    Enzymes involved in redox control are important during seed germination and seedling growth. Ascorbate-glutathione cycle enzymes in barley embryo extracts were monitored both by 2D-gel electrophoresis and activity measurements from 4 to 144 h post imbibition (PI). Strikingly different activity...... profiles were observed. No ascorbate peroxidase (APX) activity was present in mature seeds but activity was detected after 24 h PI and increased 14-fold up to 144 h PI. In contrast, dehydroascorbate reductase (DHAR) activity was present at 4 h PI and first decreased by 9-fold until 72 h PI followed by a 5......-fold increase at 144 h PI. Glutathione reductase and monodehydroascorbate reductase activities were also detected at 4 h PI, and showed modest increases of 1.8- and 2.7-fold, respectively, by 144 h PI. The combination of functional analysis with the proteomics approach enabled correlation...

  7. Oligo-carrageenan kappa increases NADPH, ascorbate and glutathione syntheses and TRR/TRX activities enhancing photosynthesis, basal metabolism, and growth in Eucalyptus trees

    Directory of Open Access Journals (Sweden)

    Alberto eGonzález

    2014-10-01

    Full Text Available In order to analyze the effect of OC kappa in redox status, photosynthesis, basal metabolism and growth in Eucalyptus globulus, trees were treated with water (control, with OC kappa at 1 mg mL-1, or treated with inhibitors of NAD(PH, ascorbate (ASC and glutathione (GSH syntheses and thioredoxin reductase (TRR activity, CHS-828, lycorine, buthionine sulfoximine (BSO and auranofin, respectively, and with OC kappa, and cultivated for 4 months. Treatment with OC kappa induced an increase in NADPH, ASC, and GSH syntheses, TRR and thioredoxin (TRX activities, photosynthesis, growth and activities of basal metabolism enzymes such as rubisco, glutamine synthetase (GlnS, adenosine 5´-phosphosulfate reductase (APR, involved in C, N and S assimilation, respectively, Krebs cycle and purine/pyrimidine synthesis enzymes. Treatment with inhibitors and OC kappa showed that increases in ASC, GSH and TRR/TRX enhanced NADPH synthesis, increases in NADPH and TRR/TRX enhanced ASC and GSH syntheses, and only the increase in NADPH enhanced TRR/TRX activities. In addition, the increase in NADPH, ASC, GSH and TRR/TRX enhanced photosynthesis and growth. Moreover, the increase in NADPH, ASC and TRR/TRX enhanced activities of rubisco, Krebs cycle and purine/pyrimidine synthesis enzymes, the increase in GSH, NADPH, and TRR/TRX enhanced APR activity, and the increase in NADPH and TRR/TRX enhanced GlnS activity. Thus, OC kappa increases NADPH, ASC and GSH syntheses leading to a more reducing redox status, the increase in NADPH, ASC, GSH syntheses and TRR/TRX activities are cross-talking events leading to activation of photosynthesis, basal metabolism and growth in Eucalyptus trees.

  8. Oligo-carrageenan kappa increases NADPH, ascorbate and glutathione syntheses and TRR/TRX activities enhancing photosynthesis, basal metabolism, and growth in Eucalyptus trees.

    Science.gov (United States)

    González, Alberto; Moenne, Fabiola; Gómez, Melissa; Sáez, Claudio A; Contreras, Rodrigo A; Moenne, Alejandra

    2014-01-01

    In order to analyze the effect of OC kappa in redox status, photosynthesis, basal metabolism and growth in Eucalyptus globulus, trees were treated with water (control), with OC kappa at 1 mg mL(-1), or treated with inhibitors of NAD(P)H, ascorbate (ASC), and glutathione (GSH) syntheses and thioredoxin reductase (TRR) activity, CHS-828, lycorine, buthionine sulfoximine (BSO), and auranofin, respectively, and with OC kappa, and cultivated for 4 months. Treatment with OC kappa induced an increase in NADPH, ASC, and GSH syntheses, TRR and thioredoxin (TRX) activities, photosynthesis, growth and activities of basal metabolism enzymes such as rubisco, glutamine synthetase (GlnS), adenosine 5'-phosphosulfate reductase (APR), involved in C, N, and S assimilation, respectively, Krebs cycle and purine/pyrimidine synthesis enzymes. Treatment with inhibitors and OC kappa showed that increases in ASC, GSH, and TRR/TRX enhanced NADPH synthesis, increases in NADPH and TRR/TRX enhanced ASC and GSH syntheses, and only the increase in NADPH enhanced TRR/TRX activities. In addition, the increase in NADPH, ASC, GSH, and TRR/TRX enhanced photosynthesis and growth. Moreover, the increase in NADPH, ASC and TRR/TRX enhanced activities of rubisco, Krebs cycle, and purine/pyrimidine synthesis enzymes, the increase in GSH, NADPH, and TRR/TRX enhanced APR activity, and the increase in NADPH and TRR/TRX enhanced GlnS activity. Thus, OC kappa increases NADPH, ASC, and GSH syntheses leading to a more reducing redox status, the increase in NADPH, ASC, GSH syntheses, and TRR/TRX activities are cross-talking events leading to activation of photosynthesis, basal metabolism, and growth in Eucalyptus trees.

  9. Interrelationship of dietary lipids and ascorbic acid with hepatic enzymes of cholesterol metabolic pathway.

    Science.gov (United States)

    Sen, S; Mukherjee, S

    1997-01-01

    Effect of unsaturated and saturated fats on cholesterol metabolism was studied in ascorbate sufficient and deficient guineapigs. Experimental animals were made chronic ascorbic acid deficient by allowing oral intake of 0.5 mg ascorbic acid/day/animal. Elevation in serum and liver cholesterol and triglyceride along with depression in cholesterol oxidation and 7 alpha-hydroxylation in liver was observed in unsaturated fat fed guineapigs with ascorbate deficiency. Liver microsomal cytochrome P-450 level was found to be low in ascorbate deficient animals. Polyunsaturated fat intake could not lower the serum cholesterol level in ascorbate deficiency. Today polyunsaturated fat in the diet is encouraged all over the world for its hypocholesterolemic effect. This study indicates that polyunsaturated fat intake with ascorbic acid deficiency may produce hypercholesterolemia.

  10. Catalase and ascorbate peroxidase-representative H2O2-detoxifying heme enzymes in plants.

    Science.gov (United States)

    Anjum, Naser A; Sharma, Pallavi; Gill, Sarvajeet S; Hasanuzzaman, Mirza; Khan, Ekhlaque A; Kachhap, Kiran; Mohamed, Amal A; Thangavel, Palaniswamy; Devi, Gurumayum Devmanjuri; Vasudhevan, Palanisamy; Sofo, Adriano; Khan, Nafees A; Misra, Amarendra Narayan; Lukatkin, Alexander S; Singh, Harminder Pal; Pereira, Eduarda; Tuteja, Narendra

    2016-10-01

    Plants have to counteract unavoidable stress-caused anomalies such as oxidative stress to sustain their lives and serve heterotrophic organisms including humans. Among major enzymatic antioxidants, catalase (CAT; EC 1.11.1.6) and ascorbate peroxidase (APX; EC 1.11.1.11) are representative heme enzymes meant for metabolizing stress-provoked reactive oxygen species (ROS; such as H2O2) and controlling their potential impacts on cellular metabolism and functions. CAT mainly occurs in peroxisomes and catalyzes the dismutation reaction without requiring any reductant; whereas, APX has a higher affinity for H2O2 and utilizes ascorbate (AsA) as specific electron donor for the reduction of H2O2 into H2O in organelles including chloroplasts, cytosol, mitochondria, and peroxisomes. Literature is extensive on the glutathione-associated H2O2-metabolizing systems in plants. However, discussion is meager or scattered in the literature available on the biochemical and genomic characterization as well as techniques for the assays of CAT and APX and their modulation in plants under abiotic stresses. This paper aims (a) to introduce oxidative stress-causative factors and highlights their relationship with abiotic stresses in plants; (b) to overview structure, occurrence, and significance of CAT and APX in plants; (c) to summarize the principles of current technologies used to assay CAT and APX in plants; (d) to appraise available literature on the modulation of CAT and APX in plants under major abiotic stresses; and finally, (e) to consider a brief cross-talk on the CAT and APX, and this also highlights the aspects unexplored so far.

  11. Identification and functional analysis of the L-ascorbate-specific enzyme II complex of the phosphotransferase system in Streptococcus mutans.

    Science.gov (United States)

    Wu, Xinyu; Hou, Jin; Chen, Xiaodan; Chen, Xuan; Zhao, Wanghong

    2016-03-22

    Streptococcus mutans is the primary etiological agent of human dental caries. It can metabolize a wide variety of carbohydrates and produce large amounts of organic acids that cause enamel demineralization. Phosphoenolpyruvate-dependent sugar phosphotransferase system (PTS) plays an important role in carbohydrates uptake of S. mutans. The ptxA and ptxB genes in S. mutans encode putative enzyme IIA and enzyme IIB of the L-ascorbate-specific PTS. The aim of this study was to analyze the function of these proteins and understand the transcriptional regulatory mechanism. ptxA (-), ptxB (-), as well as ptxA (-) , ptxB (-) double-deletion mutants all had more extended lag phase and lower growth yield than wild-type strain UA159 when grown in the medium using L-ascorbate as the sole carbon source. Acid production and acid killing assays showed that the absence of the ptxA and ptxB genes resulted in a reduction in the capacity for acidogenesis, and all three mutant strains did not survive an acid shock. According to biofilm and extracellular polysaccharides (EPS) formation analysis, all the mutant strains formed much less prolific biofilms with small amounts of EPS than wild-type UA159 when using L-ascorbate as the sole carbon source. Moreover, PCR analysis and quantitative real-time PCR revealed that sgaT, ptxA, ptxB, SMU.273, SMU.274 and SMU.275 appear to be parts of the same operon. The transcription levels of these genes were all elevated in the presence of L-ascorbate, and the expression of ptxA gene decreased significantly once ptxB gene was knockout. The ptxA and ptxB genes are involved in the growth, aciduricity, acidogenesis, and formation of biofilms and EPS of S. mutans when L-ascorbate is the sole carbon source. In addition, the expression of ptxA is regulated by ptxB. ptxA, ptxB, and the upstream gene sgaT, the downstream genes SMU.273, SMU.274 and SMU.275 appear to be parts of the same operon, and L-ascorbate is a potential inducer of the operon.

  12. Rational and combinatorial engineering of the glucan synthesizing enzyme amylosucrase

    DEFF Research Database (Denmark)

    Albenne, C.; Van Der Veen, B.A.; Potocki-Véronèse, G.

    2003-01-01

    Rational engineering of amylosucrase required detailed investigations of the molecular basis of catalysis. Biochemical characterization of the enzyme coupled to structural analyses enabled the polymerization mechanism to be elucidated. This provided key information for successfully changing amylo...

  13. Nitrile-synthesizing enzyme: Screening, purification and characterization.

    Science.gov (United States)

    Kumano, Takuto; Suzuki, Takahisa; Shimizu, Sakayu; Kobayashi, Michihiko

    2016-09-12

    Cyanide is known as a toxic compound for almost all living organisms. We have searched for cyanide-resistant bacteria from the soil and stock culture collection of our laboratory, and have found the existence of a lot of microorganisms grown on culture media containing 10 mM potassium cyanide. Almost all of these cyanide-resistant bacteria were found to show β-cyano-L-alanine (β-CNAla) synthetic activity. β-CNAla synthase is known to catalyze nitrile synthesis: the formation of β-CNAla from potassium cyanide and O-acetyl-L-serine or L-cysteine. We found that some microorganisms were able to detoxify cyanide using O-methyl-DL-serine, O-phospho-L-serine and β-chloro-DL-alanine. In addition, we purified β-CNAla synthase from Pseudomonas ovalis No. 111 in nine steps, and characterized the purified enzyme. This enzyme has a molecular mass of 60,000 and appears to consist of two identical subunits. The purified enzyme exhibits a maximum activity at pH 8.5-9.0 at an optimal temperature of 40-50°C. The enzyme is specific for O-acetyl-L-serine and β-chloro-DL-alanine. The Km value for O-acetyl-L-serine is 10.0 mM and Vmax value is 3.57 μmol/min/mg.

  14. Transcriptome mining and in silico structural and functional analysis of ascorbic acid and tartaric acid biosynthesis pathway enzymes in rose-scanted geranium.

    Science.gov (United States)

    Narnoliya, Lokesh K; Sangwan, Rajender S; Singh, Sudhir P

    2018-06-01

    Rose-scented geranium (Pelargonium sp.) is widely known as aromatic and medicinal herb, accumulating specialized metabolites of high economic importance, such as essential oils, ascorbic acid, and tartaric acid. Ascorbic acid and tartaric acid are multifunctional metabolites of human value to be used as vital antioxidants and flavor enhancing agents in food products. No information is available related to the structural and functional properties of the enzymes involved in ascorbic acid and tartaric acid biosynthesis in rose-scented geranium. In the present study, transcriptome mining was done to identify full-length genes, followed by their bioinformatic and molecular modeling investigations and understanding of in silico structural and functional properties of these enzymes. Evolutionary conserved domains were identified in the pathway enzymes. In silico physicochemical characterization of the catalytic enzymes revealed isoelectric point (pI), instability index, aliphatic index, and grand average hydropathy (GRAVY) values of the enzymes. Secondary structural prediction revealed abundant proportion of alpha helix and random coil confirmations in the pathway enzymes. Three-dimensional homology models were developed for these enzymes. The predicted structures showed significant structural similarity with their respective templates in root mean square deviation analysis. Ramachandran plot analysis of the modeled enzymes revealed that more than 84% of the amino acid residues were within the favored regions. Further, functionally important residues were identified corresponding to catalytic sites located in the enzymes. To, our best knowledge, this is the first report which provides a foundation on functional annotation and structural determination of ascorbic acid and tartaric acid pathway enzymes in rose-scanted geranium.

  15. One-pot syntheses of Li3V2(PO4)3/C cathode material for lithium ion batteries via ascorbic acid reduction approach

    International Nuclear Information System (INIS)

    Huang, J.S.; Yang, L.; Liu, K.Y.

    2011-01-01

    Highlights: → Ascorbic acid (C 6 H 8 O 6 ) was used as reducing agent and organic carbon source. → The strategy shortened the period of material preparation and lowered energy cost. → Li 3 V 2 (PO 4 ) 3 /C was obtained with enhanced electrochemical performance. → Effects of reagents on electrochemical performance of Li 3 V 2 (PO 4 ) 3 were evaluated. - Abstract: Monoclinic Li 3 V 2 (PO 4 ) 3 /C composite synthesized by ascorbic acid reduction method is examined as a cathode material for Li-ion batteries. Transmission electron microscopy (TEM) images show that the nano-size particles are obtained. The reversible capacity of Li 3 V 2 (PO 4 ) 3 /C prepared with LiOH and H 3 PO 4 is 141.2 mAh g -1 after 100 cycles at 1C discharge rate between 3 V and 4.8 V, and the retention rates of discharge capacity is 93.4%. Ascorbic acid plays not only as reduction reagent, but also as carbon sources. This strategy shortens the time of solid state reaction and facilitates the procedure of synthesis. Effects of different precursors materials on the performance of the Li 3 V 2 (PO 4 ) 3 /C are investigated.

  16. Reaction Mechanisms and Structural and Physicochemical Properties of Caffeic Acid Grafted Chitosan Synthesized in Ascorbic Acid and Hydroxyl Peroxide Redox System.

    Science.gov (United States)

    Liu, Jun; Pu, Huimin; Chen, Chong; Liu, Yunpeng; Bai, Ruyu; Kan, Juan; Jin, Changhai

    2018-01-10

    The ascorbic acid (AA) and hydroxyl peroxide (H 2 O 2 ) redox pair induced free radical grafting reaction is a promising approach to conjugate phenolic groups with chitosan (CS). In order to reveal the exact mechanisms of the AA/H 2 O 2 redox pair induced grafting reaction, free radicals generated in the AA/H 2 O 2 redox system were compared with hydroxyl radical ( • OH) produced in the Fe 2+ /H 2 O 2 redox system. Moreover, the structural and physicochemical properties of caffeic acid grafted CS (CA-g-CS) synthesized in these two redox systems were compared. Results showed that only ascorbate radical (Asc •- ) was produced in the AA/H 2 O 2 system. The reaction between Asc •- and CS produced novel carbon-centered radicals, whereas no new free radicals were detected when • OH reacted with CS. Thin layer chromatography, UV-vis, Fourier transform infrared, and nuclear magnetic resonance spectroscopic analyses all confirmed that CA was successfully grafted onto CS through Asc •- . However, CA could be hardly grafted onto CS via • OH. CA-g-CS synthesized through Asc •- exhibited lower thermal stability and crystallinity than the reaction product obtained through • OH. For the first time, our results demonstrated that the synthesis of CA-g-CS in the AA/H 2 O 2 redox system was mediated by Asc •- rather than • OH.

  17. Antisense Suppression of 2-Cysteine Peroxiredoxin in Arabidopsis Specifically Enhances the Activities and Expression of Enzymes Associated with Ascorbate Metabolism But Not Glutathione Metabolism1

    Science.gov (United States)

    Baier, Margarete; Noctor, Graham; Foyer, Christine H.; Dietz, Karl-Josef

    2000-01-01

    The aim of this study was to characterize the effect of decreased 2-cysteine peroxiredoxin (2-CP) on the leaf anti-oxidative system in Arabidopsis. At three stages of leaf development, two lines of transgenic Arabidopsis mutants with decreased contents of chloroplast 2-CP were compared with wild type and a control line transformed with an empty vector. Glutathione contents and redox state were similar in all plants, and no changes in transcript levels for enzymes involved in glutathione metabolism were observed. Transcript levels for chloroplastic glutathione peroxidase were much lower than those for 2-CP, and both cytosolic and chloroplastic glutathione peroxidase were not increased in the mutants. In contrast, the foliar ascorbate pool was more oxidized in the mutants, although the difference decreased with plant age. The activities of thylakoid and stromal ascorbate peroxidase and particularly monodehydroascorbate reductase were increased as were transcripts for these enzymes. No change in dehydroascorbate reductase activity was observed, and effects on transcript abundance for glutathione reductase, catalase, and superoxide dismutase were slight or absent. The results demonstrate that 2-CP forms an integral part of the anti-oxidant network of chloroplasts and is functionally interconnected with other defense systems. Suppression of 2-CP leads to increased expression of other anti-oxidative genes possibly mediated by increased oxidation state of the leaf ascorbate pool. PMID:11027730

  18. Nitrile-synthesizing enzyme: Gene cloning, overexpression and application for the production of useful compounds.

    Science.gov (United States)

    Kumano, Takuto; Takizawa, Yuko; Shimizu, Sakayu; Kobayashi, Michihiko

    2016-09-12

    One of the nitrile-synthesizing enzymes, β-cyano-L-alanine synthase, catalyzes β-cyano-L-alanine (β-CNAla) from potassium cyanide and O-acetyl-L-serine or L-cysteine. We have identified this enzyme from Pseudomonas ovalis No. 111. In this study, we cloned the β-CNAla synthase gene and expressed it in Escherichia coli and Rhodococcus rhodochrous. Furthermore, we carried out co-expression of β-CNAla synthase with nitrilase or nitrile hydratases in order to synthesize aspartic acid and asparagine from KCN and O-acetyl-L-serine. This strategy can be used for the synthesis of labeled amino acids by using a carbon-labeled KCN as a substrate, resulting in an application for positron emission tomography.

  19. Ascorbic Acid

    Science.gov (United States)

    Ascorbic acid is used to prevent and treat scurvy, a disease caused by a lack of vitamin C in ... Ascorbic acid comes in extended-release (long-acting) capsules and tablets, lozenges, syrup, chewable tablets, and liquid drops to ...

  20. Activation of PAF-synthesizing enzymes in rat brain stem slices after LTP induction in the medial vestibular nuclei.

    Science.gov (United States)

    Francescangeli, Ermelinda; Grassi, Silvarosa; Pettorossi, Vito E; Goracci, Gianfrancesco

    2002-11-01

    LysoPAF acetyltransferase (lysoPAF-AT) and PAF-synthesizing phosphocholinetransferase (PAF-PCT) are the two enzymes which catalyze the final reactions for the synthesis of PAF. Their activities, assayed in the homogenate of rat brain stem slices and under their optimal conditions, increased 5 min after high frequency stimulation of vestibular afferents, inducing LTP in the medial vestibular nuclei. The activity of phosphatidylcholine-synthesizing phosphocholinetransferase, was not affected. Sixty minutes from the induction of LTP, PAF-PCT activity, but not that of lysoPAF-AT, was still significantly higher with respect to 5 min test stimulated control. We used AP-5 to verify whether this increase was strictly dependent upon LTP induction, which requires NMDA receptor activation. In AP-5 treated slices, lysoPAF-acetyltransferase and PAF-synthesizing phosphocholinetransferase activities increased, but they were reduced after high frequency stimulation under AP-5. In conclusion, we have demonstrated that the activities of PAF-synthesizing enzymes are activated soon after the induction of LTP and that this effect is linked to the activation of NMDA-receptors. We suggest that the enzyme activation by AP-5, preventing LTP, might be due to glutamate enhancement but, in neurons showing LTP and under normal conditions, the activation of potentiation mechanisms is critical for the enhancement of enzyme activities.

  1. Effect of pulsed electric field treatment on enzyme kinetics and thermostability of endogenous ascorbic acid oxidase in carrots (Daucus carota cv. Nantes).

    Science.gov (United States)

    Leong, Sze Ying; Oey, Indrawati

    2014-03-01

    The objective of this research was to study the enzyme kinetics and thermostability of endogenous ascorbic acid oxidase (AAO) in carrot purée (Daucus carota cv. Nantes) after being treated with pulsed electric field (PEF) processing. Various PEF treatments using electric field strength between 0.2 and 1.2kV/cm and pulsed electrical energy between 1 and 520kJ/kg were conducted. The enzyme kinetics and the kinetics of AAO thermal inactivation (55-70°C) were described using Michaelis-Menten model and first order reaction model, respectively. Overall, the estimated Vmax and KM values were situated in the same order of magnitude as the untreated carrot purée after being exposed to pulsed electrical energy between 1 and 400kJ/kg, but slightly changed at pulsed electrical energy above 500kJ/kg. However, AAO presented different thermostability depending on the electric field strength applied. After PEF treatment at the electric field strength between 0.2 and 0.5kV/cm, AAO became thermolabile (i.e. increase in inactivation rate (k value) at reference temperature) but the temperature dependence of k value (Ea value) for AAO inactivation in carrot purée decreased, indicating that the changes in k values were less temperature dependent. It is obvious that PEF treatment affects the temperature stability of endogenous AAO. The changes in enzyme kinetics and thermostability of AAO in carrot purée could be related to the resulting carrot purée composition, alteration in intracellular environment and the effective concentration of AAO released after being subjected to PEF treatment. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. The mouse liver displays daily rhythms in the metabolism of phospholipids and in the activity of lipid synthesizing enzymes.

    Science.gov (United States)

    Gorné, Lucas D; Acosta-Rodríguez, Victoria A; Pasquaré, Susana J; Salvador, Gabriela A; Giusto, Norma M; Guido, Mario Eduardo

    2015-02-01

    The circadian system involves central and peripheral oscillators regulating temporally biochemical processes including lipid metabolism; their disruption leads to severe metabolic diseases (obesity, diabetes, etc). Here, we investigated the temporal regulation of glycerophospholipid (GPL) synthesis in mouse liver, a well-known peripheral oscillator. Mice were synchronized to a 12:12 h light-dark (LD) cycle and then released to constant darkness with food ad libitum. Livers collected at different times exhibited a daily rhythmicity in some individual GPL content with highest levels during the subjective day. The activity of GPL-synthesizing/remodeling enzymes: phosphatidate phosphohydrolase 1 (PAP-1/lipin) and lysophospholipid acyltransferases (LPLATs) also displayed significant variations, with higher levels during the subjective day and at dusk. We evaluated the temporal regulation of expression and activity of phosphatidylcholine (PC) synthesizing enzymes. PC is mainly synthesized through the Kennedy pathway with Choline Kinase (ChoK) as a key regulatory enzyme or through the phosphatidylethanolamine (PE) N-methyltransferase (PEMT) pathway. The PC/PE content ratio exhibited a daily variation with lowest levels at night, while ChoKα and PEMT mRNA expression displayed maximal levels at nocturnal phases. Our results demonstrate that mouse liver GPL metabolism oscillates rhythmically with a precise temporal control in the expression and/or activity of specific enzymes.

  3. Study of the protective effect of ascorbic acid against the toxicity of stannous chloride on oxidative damage, antioxidant enzymes and biochemical parameters in rabbits.

    Science.gov (United States)

    Yousef, M I; Awad, T I; Elhag, F A; Khaled, F A

    2007-06-25

    Stannous chloride (SnCl2) is a reducing chemical agent used in several man-made products. SnCl2 can generate reactive oxygen species (ROS). Therefore, the present study has been carried out to investigate the antioxidant action of l-ascorbic acid (AA) in minimizing SnCl2 toxicity on lipid peroxidation, antioxidant enzyme, and biochemical parameters in male New Zealand white rabbits. Animals were assigned to one of four treatment groups: 0mg AA and 0mg SnCl2/kg BW (control); 40 mg AA/kg BW; 20mg SnCl2/kg BW; 20mg SnCl2 plus 40 mg AA/kg BW. Rabbits were orally administered the respective doses every other day for 12 weeks. Results obtained showed that SnCl2 significantly (Pacid-reactive substances (TBARS; the marker of lipid peroxidation) in plasma, while the activities of glutathione S-transferase (GST), superoxide dismutase (SOD) and catalase (CAT), and the level of sulfhydryl groups (SH-group) were decreased (Pacid phosphatase (AcP) and lactate dehydrogenase (LDH) activities were decreased (Pcholesterol, triglyceride (TG), low-density lipoprotein (LDL) and very low-density lipoprotein (VLDL), glucose, urea and total bilirubin. On the other hand, the level of plasma high-density lipoprotein (HDL), total protein (TP), albumin (A) and globulin (G) were significantly (PAscorbic acid alone significantly decreased the levels of TBARS, lipids and urea, and increased the activities of GST, SOD and CAT, and the levels of SH-group and proteins. While the rest of the tested parameters were not affected. Also, the presence of AA with SnCl2 alleviated its harmful effects on most of the tested parameters. Therefore, the present results revealed that treatment with AA could minimize the toxic effects of stannous chloride.

  4. Radical SAM Enzymes in the Biosynthesis of Ribosomally Synthesized and Post-translationally Modified Peptides (RiPPs

    Directory of Open Access Journals (Sweden)

    Alhosna Benjdia

    2017-11-01

    Full Text Available Ribosomally-synthesized and post-translationally modified peptides (RiPPs are a large and diverse family of natural products. They possess interesting biological properties such as antibiotic or anticancer activities, making them attractive for therapeutic applications. In contrast to polyketides and non-ribosomal peptides, RiPPs derive from ribosomal peptides and are post-translationally modified by diverse enzyme families. Among them, the emerging superfamily of radical SAM enzymes has been shown to play a major role. These enzymes catalyze the formation of a wide range of post-translational modifications some of them having no counterparts in living systems or synthetic chemistry. The investigation of radical SAM enzymes has not only illuminated unprecedented strategies used by living systems to tailor peptides into complex natural products but has also allowed to uncover novel RiPP families. In this review, we summarize the current knowledge on radical SAM enzymes catalyzing RiPP post-translational modifications and discuss their mechanisms and growing importance notably in the context of the human microbiota.

  5. Diurnal fluctuations in cotton leaf carbon export, carbohydrate content, and sucrose synthesizing enzymes.

    Science.gov (United States)

    Hendrix, D L; Huber, S C

    1986-06-01

    In fully expanded leaves of greenhouse-grown cotton (Gossypium hirsutum L., cv Coker 100) plants, carbon export, starch accumulation rate, and carbon exchange rate exhibited different behavior during the light period. Starch accumulation rates were relatively constant during the light period, whereas carbon export rate was greater in the afternoon than in the morning even though the carbon exchange rate peaked about noon. Sucrose levels increased throughout the light period and dropped sharply with the onset of darkness; hexose levels were relatively constant except for a slight peak in the early morning. Sucrose synthase, usually thought to be a degradative enzyme, was found in unusually high activities in cotton leaf. Both sucrose synthase and sucrose phosphate synthetase activities were found to fluctuate diurnally in cotton leaves but with different rhythms. Diurnal fluctuations in the rate of sucrose export were generally aligned with sucrose phosphate synthase activity during the light period but not with sucrose synthase activity; neither enzyme activity correlated with carbon export during the dark. Cotton leaf sucrose phosphate synthase activity was sufficient to account for the observed carbon export rates; there is no need to invoke sucrose synthase as a synthetic enzyme in mature cotton leaves. During the dark a significant correlation was found between starch degradation rate and leaf carbon export. These results indicate that carbon partitioning in cotton leaf is somewhat independent of the carbon exchange rate and that leaf carbon export rate may be linked to sucrose formation and content during the light period and to starch breakdown in the dark.

  6. Amylosucrase, a glucan-synthesizing enzyme from the alpha-amylase family

    DEFF Research Database (Denmark)

    Skov, L K; Mirza, Osman Asghar; Henriksen, A

    2001-01-01

    Amylosucrase (E.C. 2.4.1.4) is a member of Family 13 of the glycoside hydrolases (the alpha-amylases), although its biological function is the synthesis of amylose-like polymers from sucrose. The structure of amylosucrase from Neisseria polysaccharea is divided into five domains: an all helical N...... of amylosucrase is at the bottom of a pocket at the molecular surface. A substrate binding site resembling the amylase 2 subsite is not found in amylosucrase. The site is blocked by a salt bridge between residues in the second and eight loops of the (beta/alpha)(8)-barrel. The result is an exo-acting enzyme. Loop......-terminal domain that is not similar to any known fold, a (beta/alpha)(8)-barrel A-domain, B- and B'-domains displaying alpha/beta-structure, and a C-terminal eight-stranded beta-sheet domain. In contrast to other Family 13 hydrolases that have the active site in the bottom of a large cleft, the active site...

  7. Expression of the neurotransmitter-synthesizing enzyme glutamic acid decarboxylase in male germ cells.

    Science.gov (United States)

    Persson, H; Pelto-Huikko, M; Metsis, M; Söder, O; Brene, S; Skog, S; Hökfelt, T; Ritzén, E M

    1990-09-01

    The gene encoding glutamic acid decarboxylase (GAD), the key enzyme in the synthesis of the inhibitory neurotransmitter gamma-aminobutyric acid, is shown to be expressed in the testis of several different species. Nucleotide sequence analysis of a cDNA clone isolated from the human testis confirmed the presence of GAD mRNA in the testis. The major GAD mRNA in the testis was 2.5 kilobases. Smaller amounts of a 3.7-kilobase mRNA with the same size as GAD mRNA in the brain was also detected in the testis. In situ hybridization using a GAD-specific probe revealed GAD mRNA expressing spermatocytes and spermatids located in the middle part of rat seminiferous tubules. Studies on the ontogeny of GAD mRNA expression showed low levels of GAD mRNA in testes of prepubertal rats, with increasing levels as sexual maturation is reached, compatible with GAD mRNA expression in germ cells. In agreement with this, fractionation of cells from the rat seminiferous epithelium followed by Northern (RNA) blot analysis showed the highest levels of GAD mRNA associated with spermatocytes and spermatids. Evidence for the presence of GAD protein in the rat testis was obtained from the demonstration of GAD-like immunoreactivity in seminiferous tubules, predominantly at a position where spermatids and spermatozoa are found. Furthermore, GAD-like immunoreactivity was seen in the midpiece of ejaculated human spermatozoa, the part that is responsible for generating energy for spermatozoan motility.

  8. Ascorbate oxidase: the unexpected involvement of a 'wasteful enzyme' in the symbioses with nitrogen-fixing bacteria and arbuscular mycorrhizal fungi.

    Science.gov (United States)

    Balestrini, Raffaella; Ott, Thomas; Güther, Mike; Bonfante, Paola; Udvardi, Michael K; De Tullio, Mario C

    2012-10-01

    Ascorbate oxidase (AO, EC 1.10.3.3) catalyzes the oxidation of ascorbate (AsA) to yield water. AO over-expressing plants are prone to ozone and salt stresses, whereas lower expression apparently confers resistance to unfavorable environmental conditions. Previous studies have suggested a role for AO as a regulator of oxygen content in photosynthetic tissues. For the first time we show here that the expression of a Lotus japonicus AO gene is induced in the symbiotic interaction with both nitrogen-fixing bacteria and arbuscular mycorrhizal (AM) fungi. In this framework, high AO expression is viewed as a possible strategy to down-regulate oxygen diffusion in root nodules, and a component of AM symbiosis. A general model of AO function in plants is discussed. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  9. Ascorbate Biosynthesis in Mitochondria Is Linked to the Electron Transport Chain between Complexes III and IV1

    Science.gov (United States)

    Bartoli, Carlos G.; Pastori, Gabriela M.; Foyer, Christine H.

    2000-01-01

    Ascorbic acid is synthesized from galactono-γ-lactone (GL) in plant tissues. An improved extraction procedure involving ammonium sulfate precipitation of membrane proteins from crude leaf homogenates yielded a simple, quick method for determining tissue activities of galactono-γ-lactone dehydrogenase (GLDH). Total foliar ascorbate and GLDH activity decreased with leaf age. Subcellular fractionation experiments using marker enzymes demonstrated that 80% of the total GLDH activity was located on the inner mitochondrial membrane, and 20% in the microsomal fraction. Specific antibody raised against potato (Solanum tuberosum L.) tuber GLDH recognized a 56-kD polypeptide in extracts from the mitochondrial membranes but failed to detect the equivalent polypeptide in microsomes. We demonstrate that isolated intact mitochondria synthesize ascorbate in the presence of GL. GL stimulated mitochondrial electron transport rates. The respiration inhibitor antimycin A stimulated ascorbate biosynthesis, while cyanide inhibited both respiration and ascorbate production. GL-dependent oxygen uptake was observed in isolated intact mitochondria. This evidence suggests that GLDH delivers electrons to the mitochondrial electron transport chain between complexes III and IV. PMID:10806250

  10. Enzyme

    Science.gov (United States)

    Enzymes are complex proteins that cause a specific chemical change in all parts of the body. For ... use them. Blood clotting is another example of enzymes at work. Enzymes are needed for all body ...

  11. Silver nanoparticles reduce brain inflammation and related neurotoxicity through induction of H2S-synthesizing enzymes

    Science.gov (United States)

    Gonzalez-Carter, Daniel A.; Leo, Bey Fen; Ruenraroengsak, Pakatip; Chen, Shu; Goode, Angela E.; Theodorou, Ioannis G.; Chung, Kian Fan; Carzaniga, Raffaella; Shaffer, Milo S. P.; Dexter, David T.; Ryan, Mary P.; Porter, Alexandra E.

    2017-03-01

    Silver nanoparticles (AgNP) are known to penetrate into the brain and cause neuronal death. However, there is a paucity in studies examining the effect of AgNP on the resident immune cells of the brain, microglia. Given microglia are implicated in neurodegenerative disorders such as Parkinson’s disease (PD), it is important to examine how AgNPs affect microglial inflammation to fully assess AgNP neurotoxicity. In addition, understanding AgNP processing by microglia will allow better prediction of their long term bioreactivity. In the present study, the in vitro uptake and intracellular transformation of citrate-capped AgNPs by microglia, as well as their effects on microglial inflammation and related neurotoxicity were examined. Analytical microscopy demonstrated internalization and dissolution of AgNPs within microglia and formation of non-reactive silver sulphide (Ag2S) on the surface of AgNPs. Furthermore, AgNP-treatment up-regulated microglial expression of the hydrogen sulphide (H2S)-synthesizing enzyme cystathionine-γ-lyase (CSE). In addition, AgNPs showed significant anti-inflammatory effects, reducing lipopolysaccharide (LPS)-stimulated ROS, nitric oxide and TNFα production, which translated into reduced microglial toxicity towards dopaminergic neurons. Hence, the present results indicate that intracellular Ag2S formation, resulting from CSE-mediated H2S production in microglia, sequesters Ag+ ions released from AgNPs, significantly limiting their toxicity, concomitantly reducing microglial inflammation and related neurotoxicity.

  12. Final report of the safety assessment of L-Ascorbic Acid, Calcium Ascorbate, Magnesium Ascorbate, Magnesium Ascorbyl Phosphate, Sodium Ascorbate, and Sodium Ascorbyl Phosphate as used in cosmetics.

    Science.gov (United States)

    Elmore, Amy R

    2005-01-01

    microscopic pathological effects were observed in either mice, rats, or guinea pigs in short-term studies. Male guinea pigs fed a control basal diet and given up to 250 mg Ascorbic Acid orally for 20 weeks had similar hemoglobin, blood glucose, serum iron, liver iron, and liver glycogen levels compared to control values. Male and female F344/N rats and B6C3F(1) mice were fed diets containing up to 100,000 ppm Ascorbic Acid for 13 weeks with little toxicity. Chronic Ascorbic Acid feeding studies showed toxic effects at dosages above 25 mg/kg body weight (bw) in rats and guinea pigs. Groups of male and female rats given daily doses up to 2000 mg/kg bw Ascorbic Acid for 2 years had no macro- or microscopically detectable toxic lesions. Mice given Ascorbic Acid subcutaneous and intravenous daily doses (500 to 1000 mg/kg bw) for 7 days had no changes in appetite, weight gain, and general behavior; and histological examination of various organs showed no changes. Ascorbic Acid was a photoprotectant when applied to mice and pig skin before exposure to ultraviolet (UV) radiation. The inhibition of UV-induced suppression of contact hypersensitivity was also noted. Magnesium Ascorbyl Phosphate administration immediately after exposure in hairless mice significantly delayed skin tumor formation and hyperplasia induced by chronic exposure to UV radiation. Pregnant mice and rats were given daily oral doses of Ascorbic Acid up to 1000 mg/kg bw with no indications of adult-toxic, teratogenic, or fetotoxic effects. Ascorbic Acid and Sodium Ascorbate were not genotoxic in several bacterial and mammalian test systems, consistent with the antioxidant properties of these chemicals. In the presence of certain enzyme systems or metal ions, evidence of genotoxicity was seen. The National Toxicology Program (NTP) conducted a 2-year oral carcinogenesis bioassay of Ascorbic Acid (25,000 and 50,000 ppm) in F344/N rats and B6C3F(1) mice. Ascorbic Acid was not carcinogenic in either sex of both rats and

  13. Bio-functionalization of electro-synthesized polypyrrole surface by heme enzyme using a mixture of Nafion and glutaraldehyde as synergetic immobilization matrix: Conformational characterization and electrocatalytic studies

    International Nuclear Information System (INIS)

    ElKaoutit, Mohammed; Naranjo-Rodriguez, Ignacio; Dominguez, Manuel; Hidalgo-Hidalgo-de-Cisneros, Jose Luis

    2011-01-01

    Use of a mixture of Nafion and glutaraldehyde as new immobilization matrix was described. The percentage of Nafion was optimized to prevent denaturation of horseradish peroxidase enzyme after its crosslinkage with glutaraldehyde on electro-synthesized polypyrrole surface. Topographic study by Atomic Force Microscopy (AFM) shows that the enzyme seems to have been introduced inside the ionic cluster of Nafion. The characterization of the resulting bio-interfaces by UV-vis and FT-IR shows that the intra-crosslinkage phenomena caused by the use of glutaraldehyde can be eliminated by the optimization of the concentration of Nafion additive. The secondary structure contents of native and immobilized enzyme were analyzed by a Gaussian curve fitting of the respective FT-IR spectra in the amide I region. Immobilized enzyme presented notable increasing percentages of globular and short helical structure compared with native enzyme. This indicates that immobilized enzyme was folded which is in accordance with AFM studies and supports the enzyme entrance inside ionic clutter of Nafion. Thanks to synergic effects of the polypyrrole conducting polymer and the perfluorosulfonic acid polymer Nafion, HRP enzyme was immobilized in its 'native' state, the resulting biosensor was able to sense peroxide without any chemical mediator and can be categorized as third generation.

  14. Bio-functionalization of electro-synthesized polypyrrole surface by heme enzyme using a mixture of Nafion and glutaraldehyde as synergetic immobilization matrix: Conformational characterization and electrocatalytic studies

    Energy Technology Data Exchange (ETDEWEB)

    ElKaoutit, Mohammed, E-mail: elkaoutit@uca.es [Departamento de Quimica Analitica, Facultad de Ciencias, Universidad de Cadiz, 11510 Puerto Real, Cadiz (Spain); Naranjo-Rodriguez, Ignacio [Departamento de Quimica Analitica, Facultad de Ciencias, Universidad de Cadiz, 11510 Puerto Real, Cadiz (Spain); Dominguez, Manuel [Departamento de Fisica de la Materia Condensada, Facultad de Ciencias, Universidad de Cadiz, 11510 Puerto Real, Cadiz (Spain); Hidalgo-Hidalgo-de-Cisneros, Jose Luis [Departamento de Quimica Analitica, Facultad de Ciencias, Universidad de Cadiz, 11510 Puerto Real, Cadiz (Spain)

    2011-10-01

    Use of a mixture of Nafion and glutaraldehyde as new immobilization matrix was described. The percentage of Nafion was optimized to prevent denaturation of horseradish peroxidase enzyme after its crosslinkage with glutaraldehyde on electro-synthesized polypyrrole surface. Topographic study by Atomic Force Microscopy (AFM) shows that the enzyme seems to have been introduced inside the ionic cluster of Nafion. The characterization of the resulting bio-interfaces by UV-vis and FT-IR shows that the intra-crosslinkage phenomena caused by the use of glutaraldehyde can be eliminated by the optimization of the concentration of Nafion additive. The secondary structure contents of native and immobilized enzyme were analyzed by a Gaussian curve fitting of the respective FT-IR spectra in the amide I region. Immobilized enzyme presented notable increasing percentages of globular and short helical structure compared with native enzyme. This indicates that immobilized enzyme was folded which is in accordance with AFM studies and supports the enzyme entrance inside ionic clutter of Nafion. Thanks to synergic effects of the polypyrrole conducting polymer and the perfluorosulfonic acid polymer Nafion, HRP enzyme was immobilized in its 'native' state, the resulting biosensor was able to sense peroxide without any chemical mediator and can be categorized as third generation.

  15. Biochemical parameters as biomarkers for the early recognition of environmental pollution on Scots pine trees. II. The antioxidative metabolites ascorbic acid, glutathione, {alpha}-tocopherol and the enzymes superoxide dismutase and glutathione reductase

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, H.; Haertling, S. [UFZ Centre for Environmental Research Leipzig-Halle, Halle (Germany). Dept. of Soil Sciences

    2001-10-01

    Field investigations with Scots pine trees (Pinus sylvestris L.) were performed in eastern Germany, where ambient SO{sub 2}, NO{sub x} and O{sub 3} concentrations differed significantly in 1992-99 at three sites, namely Neuglobsow (yearly mean SO{sub 2} in 1992: 9 {mu}g m{sup -3}), Taura (yearly mean SO{sub 2} in 1992: 54 {mu}g m{sup -3}) and Roesa (yearly mean SO{sub 2} in 1992: 73 {mu}g m{sup -3}). To investigate the effects of SO{sub 2}, NO{sub x} and O{sub 3} on antioxidants (superoxide dismutase, ascorbic acid, glutathione, glutathione reductase, {alpha}-tocopherol) and pigments including chlorophyll fluorescence as well as visible damage symptoms in the form of needle yellowing and tip necroses, needles of the 1st and 2nd age class from young and mature trees were collected at the sites every October. Eight years after the start of the field study in 1992, the ambient SO{sub 2} concentrations had decreased significantly at Neuglobsow (yearly mean SO{sub 2} in 1999: 4 {mu}g m{sup -3}), Taura (yearly mean SO{sub 2} in 1999: 5 {mu}g m{sup -3}) and Roesa (yearly mean SO{sub 2} in 1999: 5 {mu}g m{sup -3}). NO{sub x} and O{sub 3} differed less at the three sites and showed no temporal variations. Whole needle glutathione continuously decreased, although concentrations were higher in needles of the 1st and 2nd age class from the polluted sites Taura and Roesa than the unpolluted site Neuglobsow. The activities of glutathione reductase exhibited the same site-related differences and temporal variations and were correlated with concentrations of oxidized glutathione (GSSG). In contrast, the activities of the enzyme superoxide dismutase and the concentrations of whole needle ascorbic acid remained unchanged over the period. Only at the end of the investigation period did the concentrations of oxidized ascorbic acid (dehydroascorbate) increase in six-month-old needles at the polluted sites Taura and Roesa. Despite the clear decreases in SO{sub 2}, the visible symptoms

  16. Bimetallic-organic framework derived porous Co3O4/Fe3O4/C-loaded g-C3N4 nanocomposites as non-enzymic electrocatalysis oxidization toward ascorbic acid, dopamine acid, and uric acid

    Science.gov (United States)

    Hu, Bin; Liu, Yongkang; Wang, Zhuo-Wei; Song, Yingpan; Wang, Minghua; Zhang, Zhihong; Liu, Chun-Sen

    2018-05-01

    We report on the synthesis of Co- and Fe-based bimetallic nanocatalysts embedded in mesoporous carbon and g-C3N4 nanosheets (denoted as Co3O4/Fe3O4/mC@g-C3N4) for selectively simultaneous determination of ascorbic acid (AA), dopamine acid (DA), and uric acid (UA). These electrocatalysts consisting of bimetallic Co-Fe alloy nanoparticles encapsulated in N-doped carbon matrix were prepared via pyrolysis of Co/Fe-MOFs after grinding with high amounts of melamine. Chemical/crystal structures suggest high contents of mesoporous carbon in calcinated Co3O4/Fe3O4/mC nanocomposites, which exhibited enhanced electrocatalytic activity toward small biomolecules. The intrinsic performances of Co/Fe-MOFs with large specific surface area and regular nodes in the two-dimensional nanostructured g-C3N4 nanosheets endowed the as-prepared series of Co3O4/Fe3O4/mC@g-C3N4 nanocomposites with remarkable electrocatalytic activities and high adsorption ability toward oxidation of AA, DA, and UA. The developed biosensors also showed long-term stability and high selectivity for targeted analytes, with satisfactory results on actual samples in human urine. The results indicate that the as-synthesized Co3O4/Fe3O4/mC@g-C3N4 nanostructure exhibits good electrocatalytic activity and potential applications in clinical diagnosis and biosensing.

  17. Ultraviolet-B- and ozone-induced biochemical changes in antioxidant enzymes of Arabidopsis thaliana

    International Nuclear Information System (INIS)

    Rao, M.V.; Paliyath, G.; Ormrod, D.P.

    1996-01-01

    Earlier studies with Arabidopsis thaliana exposed to ultraviolet B (UV-B) and ozone (O 3 ) have indicated the differential responses of superoxide dismutase and glutathione reductase. In this study, we have investigated whether A. thaliana genotype Landsberg erecta and its flavonoid-deficient mutant transparent testa (tt5) is capable of metabolizing UV-B- and O 3 -induced activated oxygen species by invoking similar antioxidant enzymes. UV-B exposure preferentially enhanced guaiacol-peroxidases, ascorbate peroxidase, and peroxidases specific to coniferyl alcohol and modified the substrate affinity of ascorbate peroxidase. O 3 exposure enhanced superoxide dismutase, peroxidases, glutathione reductase, and ascorbate peroxidase to a similar degree and modified the substrate affinity of both glutathione reductase and ascorbate peroxidase. Both UV-B and O 3 exposure enhanced similar Cu,Zn-superoxide dismutase isoforms. New isoforms of peroxidases and ascorbate peroxidase were synthesized in tt5 plants irradiated with UV-B. UV-B radiation, in contrast to O 3 , enhanced the activation oxygen species by increasing membrane-localized NADPH-oxidase activity and decreasing catalase activities. These results collectively suggest that (a) UV-B exposure preferentially induces peroxidase-related enzymes, whereas O 3 exposure invokes the enzymes of superoxide dismutase/ascorbate-glutathione cycle, and (b) in contrast to O 3 , UV-B exposure generated activated oxygen species by increasing NADPH-oxidase activity. 10 figs., 4 tabs

  18. Entrapment of Enzymes and Carbon Nanotubes in Biologically Synthesized Silica: Glucose Oxidase-catalyzed Direct Electron Transfer, Preprint

    National Research Council Canada - National Science Library

    Invitski, Dmitri; Artyuskova, Kateryna; Rincon, Rosalba A; Atanassov, Plamen; Luckarift, Heather R; Johnson, Glenn R

    2007-01-01

    This work demonstrates a new approach for building bio-inorganic interfaces by integrating biomimetically-derived silica with single-walled carbon nanotubes to create a conductive matrix for immobilization of enzymes...

  19. Biotechnological potential of novel glycoside hydrolase family 70 enzymes synthesizing α-glucans from starch and sucrose

    NARCIS (Netherlands)

    Gangoiti, Joana; Pijning, Tjaard; Dijkhuizen, Lubbert

    Transglucosidases belonging to the glycoside hydrolase (GH) family 70 are promising enzymatic tools for the synthesis of α-glucans with defined structures from renewable sucrose and starch substrates. Depending on the GH70 enzyme specificity, α-glucans with different structures and physicochemical

  20. Novel role of a triglyceride-synthesizing enzyme: DGAT1 at the crossroad between triglyceride and cholesterol metabolism

    NARCIS (Netherlands)

    Sachdev, Vinay; Leopold, Christina; Bauer, Raimund; Patankar, Jay V.; Iqbal, Jahangir; Obrowsky, Sascha; Boverhof, Renze; Doktorova, Marcela; Scheicher, Bernhard; Goeritzer, Madeleine; Kolb, Dagmar; Turnbull, Andrew V.; Zimmer, Andreas; Hoefler, Gerald; Hussain, M. Mahmood; Groen, Albert K.; Kratky, Dagmar

    2016-01-01

    Acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1) is a key enzyme in triacylglycerol (TG) biosynthesis. Here we show that genetic deficiency and pharmacological inhibition of DGAT1 in mice alters cholesterol metabolism. Cholesterol absorption, as assessed by acute cholesterol uptake, was

  1. Structural characterization of glucosylated lactose derivatives synthesized by the Lactobacillus reuteri GtfA and Gtf180 glucansucrase enzymes.

    Science.gov (United States)

    Pham, Hien T T; Dijkhuizen, Lubbert; van Leeuwen, Sander S

    2017-09-08

    Glucansucrase enzymes from lactic acid bacteria are receiving strong interest because of their wide range of gluco-oligosaccharide and polysaccharide products from sucrose, some of which have prebiotic potential. Glucansucrases GtfA and Gtf180 from Lactobacillus reuteri strains are known to convert sucrose into α-glucans with different types of linkages, but also to use other molecules as acceptor substrates. Here we report that incubation of (N-terminally truncated versions of) these enzymes with lactose plus sucrose resulted in synthesis of at least 5 glucosylated lactose products of a degree of polymerization (DP) of 3-4. Only glucansucrase Gtf180-ΔN also produced larger lactose-based oligosaccharides (up to DP9). Structural characterization of the glucosylated lactose products DP3-4 revealed glycosidic bonds other than (α1→4)/(α1→6) typical for GtfA-ΔN and (α1→3)/(α1→6) typical for Gtf180-ΔN: Both GtfA-ΔN and Gtf180-ΔN now introduced a glucosyl residue (α1→3)- or (α1→4)-linked to the non-reducing galactose unit of lactose. Both enzymes also were able to introduce a glucosyl residue (α1→2)-linked to the reducing glucose unit of lactose. These lactose derived oligosaccharides potentially are interesting prebiotic compounds. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Response of antioxidant system of tomato to water deficit stress and its interaction with ascorbic acid

    Directory of Open Access Journals (Sweden)

    Fatemeh Daneshmand

    2014-03-01

    Full Text Available Environmental stresses including water deficit stress may produce oxidants such as reactive oxygen species that damage the membrane structure in plants. Among the antioxidants, ascorbic acid has a critical role in the cell and scavenges reactive oxygen species. In this research, effects of ascorbic acid at two levels (0 and 10 mM and water deficit stress based on 3 levels of field capacity (100, 60 and 30% were studied in tomato plants. Both levels of stress increased lipid peroxidation, reduced the amount of ascorbic acid and glutathione and increased the activity of enzymes superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase, guaiacol peroxidase and reduced the growth parameters. Ascorbic acid treatment, reduced lipid peroxidation, increased ascorbic acid and glutathione levels and decreased the activity of superoxide dismutase, catalase, ascorbate peroxidase, glutathione peroxidase and guaiacol peroxidase and positive effects of ascorbic acid treatment appeared to improve the plant growth parameters.

  3. Ascorbate concentrations in vitro and in vivo, and their role in the radiation response of cells

    International Nuclear Information System (INIS)

    Stratford, M.R.L.; Hodgkiss, R.J.

    1985-01-01

    Hydrogen-atom or electron-transfer reactions of ascorbate are often invoked in discussing its potential role in radiobiology and free radical damage by cytotoxins, but detailed information on actual levels in experimental systems is lacking. A range of 0-250 μM ascorbate is present in several commonly used mammalian cell culture media. V79 379A Chinese hamster cells can concentrate ascorbate from medium containing 200 or 500 μM ascorbate but when ascorbate is absent in medium, cells do not appear to contain a significant amount. Tumour concentrations are approximately 1mM, similar to that of glutathione (GSH). There is much current interest in depleting cells of GSH to enhance radiosensitivity, and ascorbate is maintained by a GSH dependent enzyme, glutathione dehydrogenase. Data is presented on the effect of GSH depletion by buthionine sulphoximine on cell and tumour ascorbate levels, and the effect of ascorbate on in vitro radiosensitivity, and misonidazole sensitizing efficiency

  4. Measurement of binding of ascorbic acid to myrosinase by rate of dialysis

    International Nuclear Information System (INIS)

    Ohtsuru, Masaru; Hata, Tadao

    1975-01-01

    The activation mechanism of myrosinase by L-ascorbic acid depends on the slight conformational change of enzyme protein induced by ascorbic acid. Ascorbic acid binds to enzyme like Michaelis-complex, and then the value of Km had been evaluated to be 1 x 10 -3 M. The authors determined the binding constant and the number of binding sites using dialysis rate technique. Rate dialysis was carried out with a dialysis cell, and the ordinary cellophane tubing membrane was used. ( 14 C) - ascorbic acid was added, and counted by liquid scintillation counting. By the time course of two dialysis rate measurement with and without enzyme. The concentrations of free and bound ascorbic acids were counted. From the results, the enzyme was activated to the maximum level at 10 -3 M of ascorbic acid, and four molecules of ascorbic acid bound to the enzyme on Kd=0.1x10 -4 M. However, when more than 4 molecules of L-ascorbic acid bound to the enzyme, Kd increased to 0.9x10 -4 M, and L-ascorbic acid acted as an inhibitor. (Kubatake, H.)

  5. Carotenoid β-Ring Hydroxylase and Ketolase from Marine Bacteria—Promiscuous Enzymes for Synthesizing Functional Xanthophylls

    Science.gov (United States)

    Misawa, Norihiko

    2011-01-01

    Marine bacteria belonging to genera Paracoccus and Brevundimonas of the α-Proteobacteria class can produce C40-type dicyclic carotenoids containing two β-end groups (β rings) that are modified with keto and hydroxyl groups. These bacteria produce astaxanthin, adonixanthin, and their derivatives, which are ketolated by carotenoid β-ring 4(4′)-ketolase (4(4′)-oxygenase; CrtW) and hydroxylated by carotenoid β-ring 3(3′)-hydroxylase (CrtZ). In addition, the genus Brevundimonas possesses a gene for carotenoid β-ring 2(2′)-hydroxylase (CrtG). This review focuses on these carotenoid β-ring-modifying enzymes that are promiscuous for carotenoid substrates, and pathway engineering for the production of xanthophylls (oxygen-containing carotenoids) in Escherichia coli, using these enzyme genes. Such pathway engineering researches are performed towards efficient production not only of commercially important xanthophylls such as astaxanthin, but also of xanthophylls minor in nature (e.g., β-ring(s)-2(2′)-hydroxylated carotenoids). PMID:21673887

  6. Carotenoid β-Ring Hydroxylase and Ketolase from Marine Bacteria—Promiscuous Enzymes for Synthesizing Functional Xanthophylls

    Directory of Open Access Journals (Sweden)

    Norihiko Misawa

    2011-05-01

    Full Text Available Marine bacteria belonging to genera Paracoccus and Brevundimonas of the α-Proteobacteria class can produce C40-type dicyclic carotenoids containing two β-end groups (β rings that are modified with keto and hydroxyl groups. These bacteria produce astaxanthin, adonixanthin, and their derivatives, which are ketolated by carotenoid β-ring 4(4′-ketolase (4(4′-oxygenase; CrtW and hydroxylated by carotenoid β-ring 3(3′-hydroxylase (CrtZ. In addition, the genus Brevundimonas possesses a gene for carotenoid β-ring 2(2′-hydroxylase (CrtG. This review focuses on these carotenoid β-ring-modifying enzymes that are promiscuous for carotenoid substrates, and pathway engineering for the production of xanthophylls (oxygen-containing carotenoids in Escherichia coli, using these enzyme genes. Such pathway engineering researches are performed towards efficient production not only of commercially important xanthophylls such as astaxanthin, but also of xanthophylls minor in nature (e.g., β-ring(s-2(2′-hydroxylated carotenoids.

  7. Carotenoid β-ring hydroxylase and ketolase from marine bacteria-promiscuous enzymes for synthesizing functional xanthophylls.

    Science.gov (United States)

    Misawa, Norihiko

    2011-01-01

    Marine bacteria belonging to genera Paracoccus and Brevundimonas of the α-Proteobacteria class can produce C₄₀-type dicyclic carotenoids containing two β-end groups (β rings) that are modified with keto and hydroxyl groups. These bacteria produce astaxanthin, adonixanthin, and their derivatives, which are ketolated by carotenoid β-ring 4(4')-ketolase (4(4')-oxygenase; CrtW) and hydroxylated by carotenoid β-ring 3(3')-hydroxylase (CrtZ). In addition, the genus Brevundimonas possesses a gene for carotenoid β-ring 2(2')-hydroxylase (CrtG). This review focuses on these carotenoid β-ring-modifying enzymes that are promiscuous for carotenoid substrates, and pathway engineering for the production of xanthophylls (oxygen-containing carotenoids) in Escherichia coli, using these enzyme genes. Such pathway engineering researches are performed towards efficient production not only of commercially important xanthophylls such as astaxanthin, but also of xanthophylls minor in nature (e.g., β-ring(s)-2(2')-hydroxylated carotenoids).

  8. Novel role of a triglyceride-synthesizing enzyme: DGAT1 at the crossroad between triglyceride and cholesterol metabolism.

    Science.gov (United States)

    Sachdev, Vinay; Leopold, Christina; Bauer, Raimund; Patankar, Jay V; Iqbal, Jahangir; Obrowsky, Sascha; Boverhof, Renze; Doktorova, Marcela; Scheicher, Bernhard; Goeritzer, Madeleine; Kolb, Dagmar; Turnbull, Andrew V; Zimmer, Andreas; Hoefler, Gerald; Hussain, M Mahmood; Groen, Albert K; Kratky, Dagmar

    2016-09-01

    Acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1) is a key enzyme in triacylglycerol (TG) biosynthesis. Here we show that genetic deficiency and pharmacological inhibition of DGAT1 in mice alters cholesterol metabolism. Cholesterol absorption, as assessed by acute cholesterol uptake, was significantly decreased in the small intestine and liver upon DGAT1 deficiency/inhibition. Ablation of DGAT1 in the intestine (I-DGAT1(-/-)) alone is sufficient to cause these effects. Consequences of I-DGAT1 deficiency phenocopy findings in whole-body DGAT1(-/-) and DGAT1 inhibitor-treated mice. We show that deficiency/inhibition of DGAT1 affects cholesterol metabolism via reduced chylomicron size and increased trans-intestinal cholesterol excretion. These effects are independent of cholesterol uptake at the apical surface of enterocytes but mediated through altered dietary fatty acid metabolism. Our findings provide insight into a novel role of DGAT1 and identify a pathway by which intestinal DGAT1 deficiency affects whole-body cholesterol homeostasis in mice. Targeting intestinal DGAT1 may represent a novel approach for treating hypercholesterolemia. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  9. Nicotine promotes cell proliferation via α7-nicotinic acetylcholine receptor and catecholamine-synthesizing enzymes-mediated pathway in human colon adenocarcinoma HT-29 cells

    International Nuclear Information System (INIS)

    Wong, Helen Pui Shan; Yu Le; Lam, Emily Kai Yee; Tai, Emily Kin Ki; Wu, William Ka Kei; Cho, Chi Hin

    2007-01-01

    Cigarette smoking has been implicated in colon cancer. Nicotine is a major alkaloid in cigarette smoke. In the present study, we showed that nicotine stimulated HT-29 cell proliferation and adrenaline production in a dose-dependent manner. The stimulatory action of nicotine was reversed by atenolol and ICI 118,551, a β 1 - and β 2 -selective antagonist, respectively, suggesting the role of β-adrenoceptors in mediating the action. Nicotine also significantly upregulated the expression of the catecholamine-synthesizing enzymes [tyrosine hydroxylase (TH), dopamine-β-hydroxylase (DβH) and phenylethanolamine N-methyltransferase]. Inhibitor of TH, a rate-limiting enzyme in the catecholamine-biosynthesis pathway, reduced the actions of nicotine on cell proliferation and adrenaline production. Expression of α7-nicotinic acetylcholine receptor (α7-nAChR) was demonstrated in HT-29 cells. Methyllycaconitine, an α7-nAChR antagonist, reversed the stimulatory actions of nicotine on cell proliferation, TH and DβH expression as well as adrenaline production. Taken together, through the action on α7-nAChR nicotine stimulates HT-29 cell proliferation via the upregulation of the catecholamine-synthesis pathway and ultimately adrenaline production and β-adrenergic activation. These data reveal the contributory role α7-nAChR and β-adrenoceptors in the tumorigenesis of colon cancer cells and partly elucidate the carcinogenic action of cigarette smoke on colon cancer

  10. Exogenous ascorbic acid improves defence responses of sunflower (Helianthus annuus) exposed to multiple stresses.

    Science.gov (United States)

    Kaya, Armagan

    2017-09-01

    Ascorbic acid is an important antioxidant that plays role both on growth and development and also stress response of the plant. The purpose of this study was to determine the effect of ascorbate on physiological and biochemical changes of sunflower that was exposed to multiple stresses. Chlorophyll and carotenoid contents decreased and glutathione, ascorbate and malondialdehyde contents as well as antioxidant enzyme activities increased for sunflower plant that was exposed to 50 mM NaCl and pendimethalin at different concentrations. These changes were found to be more significant in groups simultaneously exposed to both stress factors. While malondialdehyde content decreased, chlorophyll, carotenoid, ascorbate, glutathione contents and antioxidant enzyme activities increased in plants treated exogenously with ascorbate, compared to the untreated samples. According to the findings of our study; compared to individual stress, the effect of stress is more pronounced in sunflower exposed to multiple stresses, and treatment with exogenous ascorbate reduces the negative effects of stress.

  11. Nonenzymatic amperometric sensor for ascorbic acid based on hollow gold/ruthenium nanoshells

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Ara; Kang, Minkyung; Cha, Areum; Jang, Hye Su [Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750 (Korea, Republic of); Shim, Jun Ho [Department of Chemistry, Daegu University, Gyeongsan 712-714 (Korea, Republic of); Lee, Nam-Suk [National Center for Nanomaterials Technology (NCNT), Pohang University of Science and Technology (POSTECH), Pohang 790-784 (Korea, Republic of); Kim, Myung Hwa [Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750 (Korea, Republic of); Lee, Youngmi, E-mail: youngmilee@ewha.ac.kr [Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750 (Korea, Republic of); Lee, Chongmok, E-mail: cmlee@ewha.ac.kr [Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750 (Korea, Republic of)

    2014-03-01

    Highlights: • We synthesized hollow gold/ruthenium (hAu–Ru) nanoshells for ascorbic acid sensing. • The hAu–Ru nanoshells showed sensitivity of 426 μA mM⁻¹ cm⁻² for ascorbic acid. • Good selectivity against glucose, uric acid, dopamine, 4-acetamidophenol, and NADH. • The linear dynamic range appeared from zero to 2.0 mM (R = 0.9995). • Response time (1.6 s) and low detection limit (2.2 μM) were obtained at pH 7.40. Abstract: We report a new nonenzymatic amperometric detection of ascorbic acid (AA) using a glassy carbon (GC) disk electrode modified with hollow gold/ruthenium (hAu–Ru) nanoshells, which exhibited decent sensing characteristics. The hAu–Ru nanoshells were prepared by the incorporation of Ru on hollow gold (hAu) nanoshells from Co nanoparticle templates, which enabled AA selectivity against glucose without aid of enzyme or membrane. The structure and electrocatalytic activities of the hAu–Ru catalysts were characterized by spectroscopic and electrochemical techniques. The hAu–Ru loaded on GC electrode (hAu–Ru/GC) showed sensitivity of 426 μA mM⁻¹ cm⁻² (normalized to the GC disk area) for the linear dynamic range of <5 μM to 2 mM AA at physiological pH. The response time and detection limit were 1.6 s and 2.2 μM, respectively. Furthermore, the hAu–Ru/GC electrode displayed remarkable selectivity for ascorbic acid over all potential biological interferents, including glucose, uric acid (UA), dopamine (DA), 4-acetamidophenol (AP), and nicotinamide adenine dinucleotide (NADH), which could be especially good for biological sensing.

  12. Nonenzymatic amperometric sensor for ascorbic acid based on hollow gold/ruthenium nanoshells

    International Nuclear Information System (INIS)

    Jo, Ara; Kang, Minkyung; Cha, Areum; Jang, Hye Su; Shim, Jun Ho; Lee, Nam-Suk; Kim, Myung Hwa; Lee, Youngmi; Lee, Chongmok

    2014-01-01

    Highlights: • We synthesized hollow gold/ruthenium (hAu–Ru) nanoshells for ascorbic acid sensing. • The hAu–Ru nanoshells showed sensitivity of 426 μA mM −1 cm −2 for ascorbic acid. • Good selectivity against glucose, uric acid, dopamine, 4-acetamidophenol, and NADH. • The linear dynamic range appeared from zero to 2.0 mM (R = 0.9995). • Response time (1.6 s) and low detection limit (2.2 μM) were obtained at pH 7.40. - Abstract: We report a new nonenzymatic amperometric detection of ascorbic acid (AA) using a glassy carbon (GC) disk electrode modified with hollow gold/ruthenium (hAu–Ru) nanoshells, which exhibited decent sensing characteristics. The hAu–Ru nanoshells were prepared by the incorporation of Ru on hollow gold (hAu) nanoshells from Co nanoparticle templates, which enabled AA selectivity against glucose without aid of enzyme or membrane. The structure and electrocatalytic activities of the hAu–Ru catalysts were characterized by spectroscopic and electrochemical techniques. The hAu–Ru loaded on GC electrode (hAu–Ru/GC) showed sensitivity of 426 μA mM −1 cm −2 (normalized to the GC disk area) for the linear dynamic range of <5 μM to 2 mM AA at physiological pH. The response time and detection limit were 1.6 s and 2.2 μM, respectively. Furthermore, the hAu–Ru/GC electrode displayed remarkable selectivity for ascorbic acid over all potential biological interferents, including glucose, uric acid (UA), dopamine (DA), 4-acetamidophenol (AP), and nicotinamide adenine dinucleotide (NADH), which could be especially good for biological sensing

  13. The inter-relationship of ascorbate transport, metabolism and mitochondrial, plastidic respiration.

    Science.gov (United States)

    Szarka, András; Bánhegyi, Gábor; Asard, Han

    2013-09-20

    Ascorbate, this multifaceted small molecular weight carbohydrate derivative, plays important roles in a range of cellular processes in plant cells, from the regulation of cell cycle, through cell expansion and senescence. Beyond these physiological functions, ascorbate has a critical role in responses to abiotic stresses, such as high light, high salinity, or drought. The biosynthesis, recycling, and intracellular transport are important elements of the balancing of ascorbate level to the always-changing conditions and demands. A bidirectional tight relationship was described between ascorbate biosynthesis and the mitochondrial electron transfer chain (mETC), since L-galactono-1,4-lactone dehydrogenase (GLDH), the enzyme catalyzing the ultimate step of ascorbate biosynthesis, uses oxidized cytochrome c as the only electron acceptor and has a role in the assembly of Complex I. A similar bidirectional relationship was revealed between the photosynthetic apparatus and ascorbate biosynthesis since the electron flux through the photosynthetic ETC affects the biosynthesis of ascorbate and the level of ascorbate could affect photosynthesis. The details of this regulatory network of photosynthetic electron transfer, respiratory electron transfer, and ascorbate biosynthesis are still not clear, as are the potential regulatory role and the regulation of intracellular ascorbate transport and fluxes. The elucidation of the role of ascorbate as an important element of the network of photosynthetic, respiratory ETC and tricarboxylic acid cycle will contribute to understanding plant cell responses to different stress conditions.

  14. Mixed metal complexes of isoniazid and ascorbic acid: chelation ...

    African Journals Online (AJOL)

    Novel mixed complexes of isoniazid and ascorbic acid have been synthesized and characterized using infrared, electronic absorption data, elemental analysis, molar conductivity, melting point, thin layer chromatography and solubility. The metal ions involved in the complex formation are Cu2+, Zn2+ and Cd2+. The melting ...

  15. Changes in element accumulation, phenolic metabolism, and antioxidative enzyme activities in the red-skin roots of Panax ginseng.

    Science.gov (United States)

    Zhou, Ying; Yang, Zhenming; Gao, Lingling; Liu, Wen; Liu, Rongkun; Zhao, Junting; You, Jiangfeng

    2017-07-01

    Red-skin root disease has seriously decreased the quality and production of Panax ginseng (ginseng). To explore the disease's origin, comparative analysis was performed in different parts of the plant, particularly the epidermis, cortex, and/or fibrous roots of 5-yr-old healthy and diseased red-skin ginseng. The inorganic element composition, phenolic compound concentration, reactive oxidation system, antioxidant concentrations such as ascorbate and glutathione, activities of enzymes related to phenolic metabolism and oxidation, and antioxidative system particularly the ascorbate-glutathione cycle were examined using conventional methods. Aluminum (Al), iron (Fe), magnesium, and phosphorus were increased, whereas manganese was unchanged and calcium was decreased in the epidermis and fibrous root of red-skin ginseng, which also contained higher levels of phenolic compounds, higher activities of the phenolic compound-synthesizing enzyme phenylalanine ammonia-lyase and the phenolic compound oxidation-related enzymes guaiacol peroxidase and polyphenoloxidase. As the substrate of guaiacol peroxidase, higher levels of H 2 O 2 and correspondingly higher activities of superoxide dismutase and catalase were found in red-skin ginseng. Increased levels of ascorbate and glutathione; increased activities of l-galactose 1-dehydrogenase, ascorbate peroxidase, ascorbic acid oxidase, and glutathione reductase; and lower activities of dehydroascorbate reductase, monodehydroascorbate reductase, and glutathione peroxidase were found in red-skin ginseng. Glutathione- S -transferase activity remained constant. Hence, higher element accumulation, particularly Al and Fe, activated multiple enzymes related to accumulation of phenolic compounds and their oxidation. This might contribute to red-skin symptoms in ginseng. It is proposed that antioxidant and antioxidative enzymes, especially those involved in ascorbate-glutathione cycles, are activated to protect against phenolic compound

  16. The gram-negative bacterium Azotobacter chroococcum NCIMB 8003 employs a new glycoside hydrolase family 70 4,6-α-glucanotransferase enzyme (GtfD) to synthesize a reuteran like polymer from maltodextrins and starch

    NARCIS (Netherlands)

    Gangoiti, Joana; van Leeuwen, Sander S; Vafiadi, Christina; Dijkhuizen, Lubbert

    BACKGROUND: Originally the glycoside hydrolase (GH) family 70 only comprised glucansucrases of lactic acid bacteria which synthesize α-glucan polymers from sucrose. Recently we have identified 2 novel subfamilies of GH70 enzymes represented by the Lactobacillus reuteri 121 GtfB and the

  17. Stimulation of matrix formation in rabbit chondrocyte cultures by ascorbate. 1. Effect of ascorbate analogs and beta-aminopropionitrile.

    Science.gov (United States)

    Wright, G C; Wei, X Q; McDevitt, C A; Lane, B P; Sokoloff, L

    1988-01-01

    The most consistent effects of 0.2 mM L-ascorbate on monolayer cultures of rabbit articular chondrocytes were a diversion of incorporated radiosulfate into a pericellular matrix and enhancement of cell proliferation. Only with certain batches of fetal bovine serum (FBS) was there a cell-for-cell increase of proteoglycan synthesis. These actions increased as the cell inoculum rose from 0.5 to 2 x 10(5) cells/T25 flask. Maximal effects of ascorbate and D-isoascorbate were found over a range of 0.05-0.2 mM. L-Dehydroascorbic acid was less effective than either, and no stimulatory action was exerted by L-cysteine, glutathione, dithiothreitol, methylene blue, or phenazine methosulfate. Ascorbate increased the hypro:pro ratio of newly synthesized proteins. beta-Aminopropionitrile (1 mM) reduced the proportion of [3H]hydroxyproline and [35S]O4-proteoglycans in the ascorbate-supplemented matrix 31 and 7%, respectively. In corresponding electronmicrographs, the number of pericellular filaments was reduced. We conclude: (a) Ascorbate has a general anabolic effect on chondrocytes in culture and enhances matrix assembly through mechanisms other than its redox function; (b) deposition of proteoglycans in the matrix is not simply the result of mechanical entrapment by allysine- or hydroxyallysine-derived cross-linking of collagen; and (c) contradictory reports on the subject result from variations in the serum employed, inoculum density, and concentration of ascorbate.

  18. Ascorbic acid in bronchial asthma

    African Journals Online (AJOL)

    1983-04-23

    Apr 23, 1983 ... by comparing the pre-ascorbic acid results with those obtained 21/2 hours after the intravenous ... (ASO), C-reactive protein and antibodies to certain respiratory viruses. These investigations were ..... vitamin.6 However, other investigators were unable to detect any protective effects of ascorbic acid on the ...

  19. Exogenous ascorbic acid increases resistance to salt of Silybum ...

    African Journals Online (AJOL)

    However, irrigation with salt water enhanced carotenoids and antioxidant enzyme activities. The detrimental effects of salt water were ameliorated by application of 100 ppm ascorbic acid (vitamin C). The inductive role of vitamin was associated with the improvement of seed germination, growth, plant water status, ...

  20. Thylakoid-bound ascorbate peroxidase increases resistance to salt ...

    African Journals Online (AJOL)

    Reactive oxygen species (ROS) are cellular indicators of stress. In plants, they function as secondary messengers in response to environmental stress. Ascorbate peroxidase (APX) is an important enzyme directly involved in the scavenging of ROS. In this study, we aimed at identifying the function of the Brassica napus ...

  1. Role of ascorbic acid on tyrosine hydroxylase activity in the adrenal gland of guinea pig

    Energy Technology Data Exchange (ETDEWEB)

    Nakashima, Y; Sanada, H; Suzue, R; Kawada, S [National Inst. of Nutrition, Tokyo (Japan)

    1976-10-01

    The decrease of tyrosine hydroxylase activity in adrenal homogenate in scurvy was recovered after the administration of ascorbic acid. The causes of the increase in the enzyme activity after the administration of ascorbic acid have been studied. 1. No significant elevation in the enzyme activity was observed after the administration of reserpine to the scorbutic guinea pig. 2. A dose of metal chelating agent, ..cap alpha.., ..cap alpha..'-dipyridyl, prevented the ascorbic acid-induced or reserpine-induced increase in enzyme activity in the scorbutic and the nonscorbutic guinea pigs, respectively. 3. Tyrosine hydroxylase activity was partially recovered by the administration of FeSO/sub 4/ to the scorbutic guinea pig. From these results, it became clear that the induction of tyrosine hydroxylase which was not observed in scurvy was due to the deficiency of Fe/sup 2 +/. These results suggested that ascorbic acid affected the induction of this enzyme via Fe/sup 2 +/.

  2. Role of ascorbic acid on tyrosine hydroxylase activity in the adrenal gland of guinea pig

    International Nuclear Information System (INIS)

    Nakashima, Yoko; Sanada, Hiroo; Suzue, Ryokuero; Kawada, Shoji

    1976-01-01

    The decrease of tyrosine hydroxylase activity in adrenal homogenate in scurvy was recovered after the administration of ascorbic acid. The causes of the increase in the enzyme activity after the administration of ascorbic acid have been studied. 1. No significant elevation in the enzyme activity was observed after the administration of reserpine to the scorbutic guinea pig. 2. A dose of metal chelating agent, α, α'-dipyridyl, prevented the ascorbic acid-induced or reserpine-induced increase in enzyme activity in the scorbutic and the nonscorbutic guinea pigs, respectively. 3. Tyrosine hydroxylase activity was partially recovered by the administration of FeSO 4 to the scorbutic guinea pig. From these results, it became clear that the induction of tyrosine hydroxylase which was not observed in scurvy was due to the deficiency of Fe 2+ . These results suggested that ascorbic acid affected the induction of this enzyme via Fe 2+ . (auth.)

  3. Molecularly imprinted polyaniline-ferrocene-sulfonic acid-Carbon dots modified pencil graphite electrodes for chiral selective sensing of D-Ascorbic acid and L-Ascorbic acid: A clinical biomarker for preeclampsia

    International Nuclear Information System (INIS)

    Pandey, Indu; Jha, Shashank Shekhar

    2015-01-01

    Highlights: • Pencil graphite electrode was non-covalently functionalized by C-dots. • Electrochemically synthesized ferrocene-sulfonic acid doped PANI film was used as chiral recognition element. • Electrochemical chiral sensing of L-ascorbic acid and D-ascorbic acid was carried out. • L-ascorbic acid determination was done in aqueous, biological and pharmaceutical samples at nM level. - Abstract: A simple and novel method is proposed for chiral separation of L-ascorbic acid and D-ascorbic acid in human cerebrospinal fluids and blood plasma samples. Electro-polymerized molecularly imprinted poly-aniline ferrocenesulfonic acid-C-dots modified pencil graphite electrodes was successfully applied for separation and quantification of D-/L-ascorbic acid in aqueous and some biological samples. Parameters, important to control the performance of the electrochemical sensor were investigated and optimized, including the effects of pH, monomer- template ratios, electropolymerization cycles and scan rates. The molecularly imprinted film exhibited a high chiral selectivity and sensitivity towards D-ascorbic acid and L-ascorbic acid respectively. The surface morphologies and electrochemical properties of the proposed sensor were characterized by scanning electron microscopy, cyclic voltammetry, difference pulse voltammetry, chrono-amperometry and electrochemical impedance spectroscopy. L-ascorbic acid selective sensor shows excellent selectivity towards the L-ascorbic acid in comparison to D- ascorbic acid vice versa for D- ascorbic acid selective sensor. Under optimal conditions the linear range of the calibration curve for L- ascorbic acid and D- ascorbic acid was 6.0–165.0 nM and 6.0–155.0 nM, with the detection limit of 0.001 nM and 0.002 nM. Chiral detection of L-ascorbic acid was successfully carried out in pharmaceuticals and human plasma samples (pregnant women and non pregnant women) via proposed sensor with good selectivity and sensitivity.

  4. Ascorbate Peroxidase and Catalase Activities and Their Genetic Regulation in Plants Subjected to Drought and Salinity Stresses

    Directory of Open Access Journals (Sweden)

    Adriano Sofo

    2015-06-01

    Full Text Available Hydrogen peroxide (H2O2, an important relatively stable non-radical reactive oxygen species (ROS is produced by normal aerobic metabolism in plants. At low concentrations, H2O2 acts as a signal molecule involved in the regulation of specific biological/physiological processes (photosynthetic functions, cell cycle, growth and development, plant responses to biotic and abiotic stresses. Oxidative stress and eventual cell death in plants can be caused by excess H2O2 accumulation. Since stress factors provoke enhanced production of H2O2 in plants, severe damage to biomolecules can be possible due to elevated and non-metabolized cellular H2O2. Plants are endowed with H2O2-metabolizing enzymes such as catalases (CAT, ascorbate peroxidases (APX, some peroxiredoxins, glutathione/thioredoxin peroxidases, and glutathione sulfo-transferases. However, the most notably distinguished enzymes are CAT and APX since the former mainly occurs in peroxisomes and does not require a reductant for catalyzing a dismutation reaction. In particular, APX has a higher affinity for H2O2 and reduces it to H2O in chloroplasts, cytosol, mitochondria and peroxisomes, as well as in the apoplastic space, utilizing ascorbate as specific electron donor. Based on recent reports, this review highlights the role of H2O2 in plants experiencing water deficit and salinity and synthesizes major outcomes of studies on CAT and APX activity and genetic regulation in drought- and salt-stressed plants.

  5. Effect of docosahexaenoic acid and ascorbate on peroxidation of retinal membranes of ODS rats.

    Science.gov (United States)

    Wang, Jin-Ye; Sekine, Seiji; Saito, Morio

    2003-04-01

    Mutant male osteogenic disorder Shionogi (ODS) rats, unable to synthesize ascorbic acid, were fed diets containing a high content of docosahexaenoic acid (DHA) and different amounts of ascorbic acid, to study the effect of DHA on peroxidative susceptibility of the retina and possible antioxidant action of ascorbic acid. ODS rats were fed from 7 weeks of age with diets containing high DHA (6.4% of total energy). A control group received a diet high in linoleic acid. The diets also contained varying amounts of ascorbic acid. Fatty acid compositions and phospholipid hydroperoxides in rod outer segment (ROS) membranes, and retinal ascorbic acid were analyzed. DHA in ROS membranes was significantly increased in rats fed high DHA, compared with the linoleic acid diet. Levels of phospholipid hydroperoxides in the DHA-fed rats were significantly higher than the linoleic acid-fed rats. Ascorbic acid supplementation did not suppress the phospholipid hydroperoxide levels after a high DHA diet, even when the supplement increased the content of retinal ascorbic acid. In conclusion, high DHA feeding induced a marked increase of phospholipid hydroperoxides in ROS membranes of ODS rats. Supplementation of ascorbic acid did not reverse this increase.

  6. Intramolecular electron transfer in ascorbate oxidase is enhanced in the presence of oxygen

    DEFF Research Database (Denmark)

    Farver, O; Wherland, S; Pecht, I

    1994-01-01

    Intramolecular electron transfer from the type 1 copper center to the type 3 copper(II) pair is induced in the multi-copper enzyme, ascorbate oxidase, following pulse radiolytic reduction of the type 1 Cu(II) ion. In the presence of a slight excess of dioxygen over ascorbate oxidase, interaction...... between the trinuclear copper center and O2 is observed even with singly reduced ascorbate oxidase molecules. Under these conditions, the rate constant for intramolecular electron transfer from type 1 Cu(I) to type 3 Cu(II) increases 5-fold to 1100 +/- 300 s-1 (20 degrees C, pH 5.8) as compared...

  7. Biochemical Characterization of the Lactobacillus reuteri Glycoside Hydrolase Family 70 GTFB Type of 4,6-α-Glucanotransferase Enzymes That Synthesize Soluble Dietary Starch Fibers.

    Science.gov (United States)

    Bai, Yuxiang; van der Kaaij, Rachel Maria; Leemhuis, Hans; Pijning, Tjaard; van Leeuwen, Sander Sebastiaan; Jin, Zhengyu; Dijkhuizen, Lubbert

    2015-10-01

    4,6-α-Glucanotransferase (4,6-α-GTase) enzymes, such as GTFB and GTFW of Lactobacillus reuteri strains, constitute a new reaction specificity in glycoside hydrolase family 70 (GH70) and are novel enzymes that convert starch or starch hydrolysates into isomalto/maltopolysaccharides (IMMPs). These IMMPs still have linear chains with some α1→4 linkages but mostly (relatively long) linear chains with α1→6 linkages and are soluble dietary starch fibers. 4,6-α-GTase enzymes and their products have significant potential for industrial applications. Here we report that an N-terminal truncation (amino acids 1 to 733) strongly enhances the soluble expression level of fully active GTFB-ΔN (approximately 75-fold compared to full-length wild type GTFB) in Escherichia coli. In addition, quantitative assays based on amylose V as the substrate are described; these assays allow accurate determination of both hydrolysis (minor) activity (glucose release, reducing power) and total activity (iodine staining) and calculation of the transferase (major) activity of these 4,6-α-GTase enzymes. The data show that GTFB-ΔN is clearly less hydrolytic than GTFW, which is also supported by nuclear magnetic resonance (NMR) analysis of their final products. From these assays, the biochemical properties of GTFB-ΔN were characterized in detail, including determination of kinetic parameters and acceptor substrate specificity. The GTFB enzyme displayed high conversion yields at relatively high substrate concentrations, a promising feature for industrial application. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  8. 21 CFR 582.3013 - Ascorbic acid.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Ascorbic acid. 582.3013 Section 582.3013 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS... Ascorbic acid. (a) Product. Ascorbic acid. (b) Conditions of use. This substance is generally recognized as...

  9. 21 CFR 582.5013 - Ascorbic acid.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Ascorbic acid. 582.5013 Section 582.5013 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS... 1 § 582.5013 Ascorbic acid. (a) Product. Ascorbic acid. 1 Amino acids listed in this subpart may be...

  10. 21 CFR 182.8013 - Ascorbic acid.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ascorbic acid. 182.8013 Section 182.8013 Food and... CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8013 Ascorbic acid. (a) Product. Ascorbic acid. (b) Conditions of use. This substance is generally recognized as safe when used in...

  11. ANTIOXIDANT AND PRO-OXIDANT EFFECT OF ASCORBIC ACID

    Directory of Open Access Journals (Sweden)

    Goran Rankovic

    2005-01-01

    Full Text Available Free radicals attack proteins, lipids, enzymes and DNA causing pathological changes in organism. There are many mechanisms that organism uses to fight against free radicals. Ascorbic acid is one of the strongest reducers and eliminators of free radicals. It reduces stable oxygenic, azoth and thyol radicals and acts as a primary defense against water radicals in blood. When radicals are dissolved in water suspensions of erythrocytes and low density lipoproteins (LDL, ascorbic acid catches and eliminates free radicals before they arrive to the membrane and LDL molecules. Even though ascorbic acid is not capable of eliminating free radicals out of fluid medium, it acts as synergist to alpha-tocopherol in lipid section, contributes to the lessening of lipid tocoperoxil radicals, and above all, regenerates alpha-tocopherol. Ascorbic acid may act as pro-oxidant under in vitro conditions in the presence of metals; however, this effect is probably not important under in vivo conditions where metal ions, being sequestered, become second reducers.

  12. Biochemical studies on the effect of fluoride on higher plants. II. The effect of fluoride on sucrose-synthesizing enzymes from higher plants

    Energy Technology Data Exchange (ETDEWEB)

    Yang, S F; Miller, G W

    1963-01-01

    A study was initiated to characterize the properties of partially purified phosphoglucomutase, uridine diphosphate glucose pyrophosphorylase and uridine diphosphate glucose-fructose transglucosyalse, from various plant sources, with respect to activation by metal ions and inhibition by fluoride. Of the three enzymes studied, only phosphoglucomutase was very sensitive to fluoride. It is likely that the inhibition of sucrose synthesis in fluoride-fumigated plants might be due to the inhibition of phosphoglucomutase, which plays an important role in carbohydrate metabolism. However, at present, there is insufficient evidence to show the inhibition of phosphoglucomutase in vivo by fumigation with hydrogen fluoride.

  13. A metabolic switch in brain: glucose and lactate metabolism modulation by ascorbic acid.

    Science.gov (United States)

    Castro, Maite A; Beltrán, Felipe A; Brauchi, Sebastián; Concha, Ilona I

    2009-07-01

    In this review, we discuss a novel function of ascorbic acid in brain energetics. It has been proposed that during glutamatergic synaptic activity neurons preferably consume lactate released from glia. The key to this energetic coupling is the metabolic activation that occurs in astrocytes by glutamate and an increase in extracellular [K(+)]. Neurons are cells well equipped to consume glucose because they express glucose transporters and glycolytic and tricarboxylic acid cycle enzymes. Moreover, neuronal cells express monocarboxylate transporters and lactate dehydrogenase isoenzyme 1, which is inhibited by pyruvate. As glycolysis produces an increase in pyruvate concentration and a decrease in NAD(+)/NADH, lactate and glucose consumption are not viable at the same time. In this context, we discuss ascorbic acid participation as a metabolic switch modulating neuronal metabolism between rest and activation periods. Ascorbic acid is highly concentrated in CNS. Glutamate stimulates ascorbic acid release from astrocytes. Ascorbic acid entry into neurons and within the cell can inhibit glucose consumption and stimulate lactate transport. For this switch to occur, an ascorbic acid flow is necessary between astrocytes and neurons, which is driven by neural activity and is part of vitamin C recycling. Here, we review the role of glucose and lactate as metabolic substrates and the modulation of neuronal metabolism by ascorbic acid.

  14. Ascorbate oxidase is the potential conductor of a symphony of signaling pathways.

    Science.gov (United States)

    De Tullio, Mario C; Guether, Mike; Balestrini, Raffaella

    2013-03-01

    The functional role of ascorbate oxidase (AO; EC 1.10.3.3) has never been fully explained so far, due to the difficulties in understanding the presence of an enzyme specifically oxidizing ascorbate with no obvious advantage, and the apparent disadvantage of lowering plant stress resistance as a consequence of ascorbate consumption. Here we suggest a complete change of perspective, by proposing an essential role of AO as a modulator of both ascorbate and oxygen content, with relevant implications related to signaling. By affecting the overall redox state, AO is actually involved in redox regulation in the extracellular matrix. In addition, AO can contribute to creating a hypoxic microenvironment, especially relevant in the maintenance of meristem identity and the establishment of mutualistic plant-microbe interactions. We also hypothesize the possible involvement of AO in the activation of a signaling cascade analogous to the mechanism of prolyl hydroxylases/Hypoxia Inducible Factors in animals.

  15. The human neonatal small intestine has the potential for arginine synthesis; developmental changes in the expression of arginine-synthesizing and -catabolizing enzymes

    Directory of Open Access Journals (Sweden)

    Ruijter Jan M

    2008-11-01

    Full Text Available Abstract Background Milk contains too little arginine for normal growth, but its precursors proline and glutamine are abundant; the small intestine of rodents and piglets produces arginine from proline during the suckling period; and parenterally fed premature human neonates frequently suffer from hypoargininemia. These findings raise the question whether the neonatal human small intestine also expresses the enzymes that enable the synthesis of arginine from proline and/or glutamine. Carbamoylphosphate synthetase (CPS, ornithine aminotransferase (OAT, argininosuccinate synthetase (ASS, arginase-1 (ARG1, arginase-2 (ARG2, and nitric-oxide synthase (NOS were visualized by semiquantitative immunohistochemistry in 89 small-intestinal specimens. Results Between 23 weeks of gestation and 3 years after birth, CPS- and ASS-protein content in enterocytes was high and then declined to reach adult levels at 5 years. OAT levels declined more gradually, whereas ARG-1 was not expressed. ARG-2 expression increased neonatally to adult levels. Neurons in the enteric plexus strongly expressed ASS, OAT, NOS1 and ARG2, while varicose nerve fibers in the circular layer of the muscularis propria stained for ASS and NOS1 only. The endothelium of small arterioles expressed ASS and NOS3, while their smooth-muscle layer expressed OAT and ARG2. Conclusion The human small intestine acquires the potential to produce arginine well before fetuses become viable outside the uterus. The perinatal human intestine therefore resembles that of rodents and pigs. Enteral ASS behaves as a typical suckling enzyme because its expression all but disappears in the putative weaning period of human infants.

  16. Characterization of the galactono-1,4-lactone dehydrogenase from pepper fruits and its modulation in the ascorbate biosynthesis. Role of nitric oxide

    Directory of Open Access Journals (Sweden)

    Marta Rodríguez-Ruiz

    2017-08-01

    Full Text Available Pepper fruit is one of the highest vitamin C sources of plant origin for our diet. In plants, ascorbic acid is mainly synthesized through the L-galactose pathway, being the L-galactono-1,4-lactone dehydrogenase (GalLDH the last step. Using pepper fruits, the full GalLDH gene was cloned and the protein molecular characterization accomplished. GalLDH protein sequence (586 residues showed a 37 amino acids signal peptide at the N-terminus, characteristic of mitochondria. The hydrophobic analysis of the mature protein displayed one transmembrane helix comprising 20 amino acids at the N-terminus. By using a polyclonal antibody raised against a GalLDH internal sequence and immunoblotting analysis, a 56 kDa polypeptide cross-reacted with pepper fruit samples. Using leaves, flowers, stems and fruits, the expression of GalLDH by qRT-PCR and the enzyme activity were analyzed, and results indicate that GalLDH is a key player in the physiology of pepper plants, being possibly involved in the processes which undertake the transport of ascorbate among different organs.We also report that an NO (nitric oxide-enriched atmosphere enhanced ascorbate content in pepper fruits about 40% parallel to increased GalLDH gene expression and enzyme activity. This is the first report on the stimulating effect of NO treatment on the vitamin C concentration in plants. Accordingly, the modulation by NO of GalLDH was addressed. In vitro enzymatic assays of GalLDH were performed in the presence of SIN-1 (peroxynitrite donor and S-nitrosoglutahione (NO donor. Combined results of in vivo NO treatment and in vitro assays showed that NO provoked the regulation of GalLDH at transcriptional and post-transcriptional levels, but not post-translational modifications through nitration or S-nitrosylation events promoted by reactive nitrogen species (RNS took place. These results suggest that this modulation point of the ascorbate biosynthesis could be potentially used for biotechnological

  17. Copper@carbon coaxial nanowires synthesized by hydrothermal carbonization process from electroplating wastewater and their use as an enzyme-free glucose sensor.

    Science.gov (United States)

    Zhao, Yuxin; He, Zhaoyang; Yan, Zifeng

    2013-01-21

    In the pursuit of electrocatalysts with great economic and ecological values for non-enzymatic glucose sensors, one-dimensional copper@carbon (Cu@C) core-shell coaxial nanowires (NWs) have been successfully prepared via a simple continuous flow wet-chemistry approach from electroplating wastewater. The as-obtained products were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, energy dispersive X-ray spectroscopy and Raman spectroscopy. The electrocatalytic activity of the modified electrodes by Cu@C NWs towards glucose oxidation was investigated by cyclic voltammetry and chronoamperometry. It was found that the as-obtained Cu@C NWs showed good electrochemical properties and could be used as an electrochemical sensor for the detection of glucose molecules. Compared to the other electrodes including the bare Nafion/glassy carbon electrode (GCE) and several hot hybrid nanostructures modified GCE, a substantial decrease in the overvoltage of the glucose oxidation was observed at the Cu@C NWs electrodes with oxidation starting at ca. 0.20 V vs. Ag/AgCl (3 M KCl). At an applied potential of 0.65 V, Cu@C NWs electrodes had a high and reproducible sensitivity of 437.8 µA cm(-2) mM(-1) to glucose. Linear responses were obtained with a detection limit of 50 nM. More importantly, the proposed electrode also had good stability, high resistance against poisoning by chloride ion and commonly interfering species. These good analytical performances make Cu@C NWs promising for the future development of enzyme-free glucose sensors.

  18. Impact of Oxidative Stress on Ascorbate Biosynthesis in Chlamydomonas via Regulation of the VTC2 Gene Encoding a GDP-l-galactose Phosphorylase*

    Science.gov (United States)

    Urzica, Eugen I.; Adler, Lital N.; Page, M. Dudley; Linster, Carole L.; Arbing, Mark A.; Casero, David; Pellegrini, Matteo; Merchant, Sabeeha S.; Clarke, Steven G.

    2012-01-01

    The l-galactose (Smirnoff-Wheeler) pathway represents the major route to l-ascorbic acid (vitamin C) biosynthesis in higher plants. Arabidopsis thaliana VTC2 and its paralogue VTC5 function as GDP-l-galactose phosphorylases converting GDP-l-galactose to l-galactose-1-P, thus catalyzing the first committed step in the biosynthesis of l-ascorbate. Here we report that the l-galactose pathway of ascorbate biosynthesis described in higher plants is conserved in green algae. The Chlamydomonas reinhardtii genome encodes all the enzymes required for vitamin C biosynthesis via the l-galactose pathway. We have characterized recombinant C. reinhardtii VTC2 as an active GDP-l-galactose phosphorylase. C. reinhardtii cells exposed to oxidative stress show increased VTC2 mRNA and l-ascorbate levels. Genes encoding enzymatic components of the ascorbate-glutathione system (e.g. ascorbate peroxidase, manganese superoxide dismutase, and dehydroascorbate reductase) are also up-regulated in response to increased oxidative stress. These results indicate that C. reinhardtii VTC2, like its plant homologs, is a highly regulated enzyme in ascorbate biosynthesis in green algae and that, together with the ascorbate recycling system, the l-galactose pathway represents the major route for providing protective levels of ascorbate in oxidatively stressed algal cells. PMID:22393048

  19. 21 CFR 182.3013 - Ascorbic acid.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ascorbic acid. 182.3013 Section 182.3013 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... acid. (a) Product. Ascorbic acid. (b) Conditions of use. This substance is generally recognized as safe...

  20. Tumorigenicity of sodium ascorbate in male rats.

    Science.gov (United States)

    Cohen, S M; Anderson, T A; de Oliveira, L M; Arnold, L L

    1998-06-15

    Sodium ascorbate, like other sodium salts such as saccharin, glutamate, and bicarbonate, produces urinary alterations when fed at high doses to rats, which results in mild superficial urothelial cytotoxicity and regeneration but not tumors in a standard 2-year bioassay. Sodium saccharin was shown to produce a low incidence of bladder tumors in rats if administered in a two-generation bioassay. In the present study, we evaluated sodium ascorbate in a two-generation bioassay that involved feeding to the male and female parental F344 rats for 4 weeks before mating, feeding the dams during gestation and lactation, and then feeding the weaned (at 28 days of age) male F1 generation rats for the remainder of their lifetime (up to 128 weeks of the experiment). Dietary levels of 1.0, 5.0, and 7.0% sodium ascorbate were tested. At 5.0 and 7.0% sodium ascorbate, there was an increase in urinary bladder urothelial papillary and nodular hyperplasia and the induction of a few papillomas and carcinomas. There was a dose-responsive increase in renal pelvic calcification and hyperplasia and inhibition of the aging nephropathy of rats even at the level of 1% sodium ascorbate. Because the short-term urothelial effects of sodium ascorbate in rats are inhibited by treatments producing urinary acidification to pH sodium ascorbate to evaluate the long-term effects. The combination of 7.0% sodium ascorbate plus 2.78% NH4Cl in the diet was toxic, and the group was terminated early during the course of the experiment. The group fed 5.0% sodium ascorbate plus 2.04% NH4Cl showed complete inhibition of the urothelial effects of sodium ascorbate and significant inhibition of its renal effects. We also demonstrated the presence of a calcium phosphate-containing urinary precipitate in rats fed sodium ascorbate at all doses, in a dose-responsive manner. The formation of the precipitate was inhibited by coadministration with NH4Cl. The proliferative effects of sodium ascorbate on the male rat

  1. Characterization of the galactono-1,4-lactone dehydrogenase from pepper fruits and its modulation in the ascorbate biosynthesis. Role of nitric oxide.

    Science.gov (United States)

    Rodríguez-Ruiz, Marta; Mateos, Rosa M; Codesido, Verónica; Corpas, Francisco J; Palma, José M

    2017-08-01

    Pepper fruit is one of the highest vitamin C sources of plant origin for our diet. In plants, ascorbic acid is mainly synthesized through the L-galactose pathway, being the L-galactono-1,4-lactone dehydrogenase (GalLDH) the last step. Using pepper fruits, the full GalLDH gene was cloned and the protein molecular characterization accomplished. GalLDH protein sequence (586 residues) showed a 37 amino acids signal peptide at the N-terminus, characteristic of mitochondria. The hydrophobic analysis of the mature protein displayed one transmembrane helix comprising 20 amino acids at the N-terminus. By using a polyclonal antibody raised against a GalLDH internal sequence and immunoblotting analysis, a 56kDa polypeptide cross-reacted with pepper fruit samples. Using leaves, flowers, stems and fruits, the expression of GalLDH by qRT-PCR and the enzyme activity were analyzed, and results indicate that GalLDH is a key player in the physiology of pepper plants, being possibly involved in the processes which undertake the transport of ascorbate among different organs. We also report that an NO (nitric oxide)-enriched atmosphere enhanced ascorbate content in pepper fruits about 40% parallel to increased GalLDH gene expression and enzyme activity. This is the first report on the stimulating effect of NO treatment on the vitamin C concentration in plants. Accordingly, the modulation by NO of GalLDH was addressed. In vitro enzymatic assays of GalLDH were performed in the presence of SIN-1 (peroxynitrite donor) and S-nitrosoglutahione (NO donor). Combined results of in vivo NO treatment and in vitro assays showed that NO provoked the regulation of GalLDH at transcriptional and post-transcriptional levels, but not post-translational modifications through nitration or S-nitrosylation events promoted by reactive nitrogen species (RNS) took place. These results suggest that this modulation point of the ascorbate biosynthesis could be potentially used for biotechnological purposes to

  2. Separation of DR synthesized Ti-Mg Alloy by dissolution of waste by-products in acid media

    CSIR Research Space (South Africa)

    Mushove, T

    2010-06-01

    Full Text Available The objective of this work is to isolate synthesized Ti-Mg alloy powder through leaching out of MgO and any unreduced oxides of Titanium. Leaching media investigated are H2SO4, HCl and organic acids ascorbic acid/oxalic and L-cysteine /ascorbic...

  3. Synthesis of colloidal silver nanoparticle clusters and their application in ascorbic acid detection by SERS.

    Science.gov (United States)

    Cholula-Díaz, Jorge L; Lomelí-Marroquín, Diana; Pramanick, Bidhan; Nieto-Argüello, Alfonso; Cantú-Castillo, Luis A; Hwang, Hyundoo

    2018-03-01

    Ascorbic acid (vitamin C) has an essential role in the human body mainly due to its antioxidant function. In this work, metallic silver nanoparticle (AgNP) colloids were used in SERS experiments to detect ascorbic acid in aqueous solution. The AgNPs were synthesized by a green method using potato starch as reducing and stabilizing agent, and water as the solvent. The optical properties of the yellowish as-synthesized silver colloids were characterized by UV-vis spectroscopy, in which besides a typical band at 410 nm related to the localized surface plasmon resonance of the silver nanoparticles, a shoulder band around 500 nm, due to silver nanoparticle cluster formation, is presented when relatively higher concentrations of starch are used in the synthesis. These starch-capped silver nanoparticles show an intrinsic Raman peak at 1386 cm -1 assigned to deformation modes of the starch structure. The increase of the intensity of the SERS peak at 1386 cm -1 with an increase in the concentration of the ascorbic acid is related to a decrease of the gap between dimers and trimers of the silver nanoparticle clusters produced by the presence of ascorbic acid in the colloid. The limit of detection of this technique for ascorbic acid is 0.02 mM with a measurement concentration range of 0.02-10 mM, which is relevant for the application of this method for detecting ascorbic acid in biological specimen. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Interference-Blind Microfluidic Sensor for Ascorbic Acid Determination by UV/vis Spectroscopy

    DEFF Research Database (Denmark)

    Bi, Hongyan; Oliveira Fernandes, Ana Carolina; Cardoso, Susana

    2016-01-01

    A microfluidic sensor is developed and targeted at specific ingredients determination in drug/food/beverage matrices. The surface of a serpentine polydimethylsiloxane (PDMS) microchannel is modified by enzyme via physisorption. When solutions containing target ingredients pass through...... the microfluidic channel, enzyme-catalyzed reaction occurs and only converts the target molecules to its products. The whole process is monitored by an end-channel UV/vis spectroscopic detection. Ascorbate oxidase and L-ascorbic acid (AA) are taken as enzyme-substrate model in this study to investigate......, specific, and accurate, and can be potentially used for fast quantification of ingredient in samples with complex matrix background. It is promising to be widely spread in food industry and quality control department...

  5. Oxidative Stress in The Hippocampus During Experimental Seizures Can Be Ameliorated With The Antioxidant Ascorbic Acid

    Directory of Open Access Journals (Sweden)

    Ítala Mônica Sales Santos

    2009-01-01

    Full Text Available Ascorbic acid has many nonenzymatic actions and is a powerful water-soluble antioxidant. It protects low density lipoproteins from oxidation and reduces harmful oxidants in the central nervous system. Pilocarpine-induced seizures have been suggested to be mediated by increases in oxidative stress. Current studies have suggested that antioxidant compounds may afford some level of neuroprotection against the neurotoxicity of seizures. The objective of the present study was to evaluate the neuroprotective effects of ascorbic acid (AA in rats, against the observed oxidative stress during seizures induced by pilocarpine. Wistar rats were treated with 0.9% saline (i.p., control group, ascorbic acid (500 mg/kg, i.p., AA group, pilocarpine (400 mg/kg, i.p., pilocarpine group, and the association of ascorbic acid (500 mg/kg, i.p. plus pilocarpine (400 mg/kg, i.p., 30 min before of administration of ascorbic acid (AA plus pilocarpine group. After the treatments all groups were observed for 6 h. The enzyme activities as well as the lipid peroxidation and nitrite concentrations were measured using spectrophotometric methods and the results compared to values obtained from saline and pilocarpine-treated animals. Protective effects of ascorbic acid were also evaluated on the same parameters. In pilocarpine group there was a significant increase in lipid peroxidation and nitrite level. However, no alteration was observed in superoxide dismutase and catalase activities. Antioxidant treatment significantly reduced the lipid peroxidation level and nitrite content as well as increased the superoxide dismutase and catalase activities in hippocampus of adult rats after seizures induced by pilocarpine. Our findings strongly support the hypothesis that oxidative stress in hippocampus occurs during seizures induced by pilocarpine, proving that brain damage induced by the oxidative process plays a crucial role in seizures pathogenic consequences, and also imply that a

  6. Fate of the synergistic antioxidant system ascorbic acid, lecithin, and tocopherol in mayonnaise: Partion of ascorbic acid

    DEFF Research Database (Denmark)

    Meyer, Anne Merete Boye; Jacobsen, Charlotte Munch

    1996-01-01

    Meyer, A. S. & C. Jacobsen, 1996. Fate of the synergistic antioxidant system ascorbic acid, lecithin, and tocopherol in mayonnaise: Partion of ascorbic acid, J. Food Lipids, 3, 139-147.......Meyer, A. S. & C. Jacobsen, 1996. Fate of the synergistic antioxidant system ascorbic acid, lecithin, and tocopherol in mayonnaise: Partion of ascorbic acid, J. Food Lipids, 3, 139-147....

  7. The glutamate aspartate transporter (GLAST) mediates L-glutamate-stimulated ascorbate-release via swelling-activated anion channels in cultured neonatal rodent astrocytes.

    Science.gov (United States)

    Lane, Darius J R; Lawen, Alfons

    2013-03-01

    Vitamin C (ascorbate) plays important neuroprotective and neuromodulatory roles in the mammalian brain. Astrocytes are crucially involved in brain ascorbate homeostasis and may assist in regenerating extracellular ascorbate from its oxidised forms. Ascorbate accumulated by astrocytes can be released rapidly by a process that is stimulated by the excitatory amino acid, L-glutamate. This process is thought to be neuroprotective against excitotoxicity. Although of potential clinical interest, the mechanism of this stimulated ascorbate-release remains unknown. Here, we report that primary cultures of mouse and rat astrocytes release ascorbate following initial uptake of dehydroascorbate and accumulation of intracellular ascorbate. Ascorbate-release was not due to cellular lysis, as assessed by cellular release of the cytosolic enzyme lactate dehydrogenase, and was stimulated by L-glutamate and L-aspartate, but not the non-excitatory amino acid L-glutamine. This stimulation was due to glutamate-induced cellular swelling, as it was both attenuated by hypertonic and emulated by hypotonic media. Glutamate-stimulated ascorbate-release was also sensitive to inhibitors of volume-sensitive anion channels, suggesting that the latter may provide the conduit for ascorbate efflux. Glutamate-stimulated ascorbate-release was not recapitulated by selective agonists of either ionotropic or group I metabotropic glutamate receptors, but was completely blocked by either of two compounds, TFB-TBOA and UCPH-101, which non-selectively and selectively inhibit the glial Na(+)-dependent excitatory amino acid transporter, GLAST, respectively. These results suggest that an impairment of astrocytic ascorbate-release may exacerbate neuronal dysfunction in neurodegenerative disorders and acute brain injury in which excitotoxicity and/or GLAST deregulation have been implicated.

  8. Interference of ascorbic acid with chemical analytes.

    Science.gov (United States)

    Meng, Qing H; Irwin, William C; Fesser, Jennifer; Massey, K Lorne

    2005-11-01

    Ascorbic acid can interfere with methodologies involving redox reactions, while comprehensive studies on main chemistry analysers have not been reported. We therefore attempted to determine the interference of ascorbic acid with analytes on the Beckman Synchron LX20. Various concentrations of ascorbic acid were added to serum, and the serum analytes were measured on the LX20. With a serum ascorbic acid concentration of 12.0 mmol/L, the values for sodium, potassium, calcium and creatinine increased by 43%, 58%, 103% and 26%, respectively (Pascorbic acid concentration of 12.0 mmol/L, the values for chloride, total bilirubin and uric acid decreased by 33%, 62% and 83%, respectively (Pcholesterol, triglyceride, ammonia and lactate. There was no definite influence of ascorbic acid on analytical values for total CO(2), urea, glucose, phosphate, total protein, albumin, amylase, creatine kinase, creatine kinase-MB, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, total iron, unbound iron-binding capacity or magnesium. Ascorbic acid causes a false increase in sodium, potassium, calcium and creatinine results and a false decrease in chloride, total bilirubin, uric acid, total cholesterol, triglyceride, ammonia and lactate results.

  9. Dietary taurine alters ascorbic acid metabolism in rats fed diets containing polychlorinated biphenyls.

    Science.gov (United States)

    Mochizuki, H; Oda, H; Yokogoshi, H

    2000-04-01

    The effect of dietary taurine on ascorbic acid metabolism and hepatic drug-metabolizing enzymes was investigated in rats fed diets containing polychlorinated biphenyls (PCB) to determine whether taurine has an adaptive and protective function in xenobiotic-treated animals. Young male Wistar rats (60 g) were fed diets containing 0 or 0.2 g/kg diet PCB with or without 30 g/kg diet of taurine for 14 d. The rats fed the PCB-containing diets had greater liver weight, higher ascorbic acid concentrations in the liver and spleen and greater hepatic cytochrome P-450 contents than control rats that were not treated with PCB (P ascorbic acid excretion was enhanced, and serum cholesterol concentration (especially HDL-cholesterol) was significantly elevated compared with those in control rats. Dietary taurine significantly potentiated the increases in the urinary excretion of ascorbic acid and the rise in the levels of cytochrome P-450 which were caused by PCB treatment. On the other hand, the supplementation of taurine to control diet did not alter these variables. Taurine may enhance the hepatic drug-metabolizing systems, leading to the stimulation of the ascorbic acid metabolism in rats fed diets containing PCB.

  10. Localization of ascorbic acid, ascorbic acid oxidase, and glutathione in roots of Cucurbita maxima L.

    Science.gov (United States)

    Liso, Rosalia; De Tullio, Mario C; Ciraci, Samantha; Balestrini, Raffaella; La Rocca, Nicoletta; Bruno, Leonardo; Chiappetta, Adriana; Bitonti, Maria Beatrice; Bonfante, Paola; Arrigoni, Oreste

    2004-12-01

    To understand the function of ascorbic acid (ASC) in root development, the distribution of ASC, ASC oxidase, and glutathione (GSH) were investigated in cells and tissues of the root apex of Cucubita maxima. ASC was regularly distributed in the cytosol of almost all root cells, with the exception of quiescent centre (QC) cells. ASC also occurred at the surface of the nuclear membrane and correspondingly in the nucleoli. No ASC could be observed in vacuoles. ASC oxidase was detected by immunolocalization mainly in cell walls and vacuoles. This enzyme was particularly abundant in the QC and in differentiating vascular tissues and was absent in lateral root primordia. Administration of the ASC precursor L-galactono-gamma-lactone markedly increased ASC content in all root cells, including the QC. Root treatment with the ASC oxidized product, dehydroascorbic acid (DHA), also increased ASC content, but caused ASC accumulation only in peripheral tissues, where DHA was apparently reduced at the expense of GSH. The different pattern of distribution of ASC in different tissues and cell compartments reflects its possible role in cell metabolism and root morphogenesis.

  11. Thermal stability of L-ascorbic acid and ascorbic acid oxidase in broccoli (Brassica oleracea var. italica).

    Science.gov (United States)

    Munyaka, Ann Wambui; Makule, Edna Edward; Oey, Indrawati; Van Loey, Ann; Hendrickx, Marc

    2010-05-01

    The thermal stability of vitamin C (including l-ascorbic acid [l-AA] and dehydroascorbic acid [DHAA]) in crushed broccoli was evaluated in the temperature range of 30 to 90 degrees C whereas that of ascorbic acid oxidase (AAO) was evaluated in the temperature range of 20 to 95 degrees C. Thermal treatments (for 15 min) of crushed broccoli at 30 to 60 degrees C resulted in conversion of l-AA to DHAA whereas treatments at 70 to 90 degrees C retained vitamin C as l-AA. These observations indicated that enzymes (for example, AAO) could play a major role in the initial phase (that is, oxidation of l-AA to DHAA) of vitamin C degradation in broccoli. Consequently, a study to evaluate the temperature-time conditions that could result in AAO inactivation in broccoli was carried out. In this study, higher AAO activity was observed in broccoli florets than stalks. During thermal treatments for 10 min, AAO in broccoli florets and stalks was stable until around 50 degrees C. A 10-min thermal treatment at 80 degrees C almost completely inactivated AAO in broccoli. AAO inactivation followed 1st order kinetics in the temperature range of 55 to 65 degrees C. Based on this study, a thermal treatment above 70 degrees C is recommended for crushed vegetable products to prevent oxidation of l-AA to DHAA, the onset of vitamin C degradation. The results reported in this study are applicable for both domestic and industrial processing of vegetables into products such as juices, soups, and purees. In this report, we have demonstrated that processing crushed broccoli in a temperature range of 30 to 60 degrees C could result in the conversion of l-ascorbic acid to dehydroascorbic (DHAA), a very important reaction in regard to vitamin C degradation because DHAA could be easily converted to other compounds that do not have the biological activity of vitamin C.

  12. Mechanism of melatonin protection against copper-ascorbate-induced oxidative damage in vitro through isothermal titration calorimetry.

    Science.gov (United States)

    Ghosh, Arnab K; Naaz, Shamreen; Bhattacharjee, Bharati; Ghosal, Nirajan; Chattopadhyay, Aindrila; Roy, Souvik; Reiter, Russel J; Bandyopadhyay, Debasish

    2017-07-01

    Involvement of oxidative stress in cardiovascular diseases is well established. Melatonin's role as an antioxidant and free radical scavenger via its receptor dependent and receptor independent pathways is well known. The aim of this study is to identify and elaborate upon a third mechanism by which melatonin is able to abrogate oxidative stress. Oxidative stress was induced in vitro, by copper (0.2mM)-ascorbate (1mM) in isolated goat heart mitochondria, cytosol and peroxisomes and they were co-incubated with graded doses of melatonin. Similar experiments in a cell-free chemical system involving two pure antioxidant enzymes, Cu-Zn superoxide dismutase and catalase was also carried out. Biochemical changes in activity of these antioxidant enzymes were analysed. Isothermal titration calorimetric studies with pure Cu-Zn superoxide dismutase and catalase were also carried out. Incubation with copper-ascorbate led to alteration in activity of Cu-Zn superoxide dismutase and catalase which were found to be protected upon co-incubation with melatonin (80μM for catalase and 1μM for others). Results of isothermal titration calorimetric studies with pure Cu-Zn superoxide dismutase and catalase along with different combinations of copper chloride, ascorbic acid and melatonin suggest that when melatonin is present in the reaction medium along with copper-ascorbate, it restrains the copper-ascorbate molecules by binding with them physically along with scavenging the free radicals generated by them. The present study suggests that possibly, binding of melatonin with antioxidant enzymes masks the vulnerable sites of these antioxidant enzymes, thus preventing oxidative damage by copper-ascorbate molecules. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Drug Nanoparticle Formulation Using Ascorbic Acid Derivatives

    Directory of Open Access Journals (Sweden)

    Kunikazu Moribe

    2011-01-01

    Full Text Available Drug nanoparticle formulation using ascorbic acid derivatives and its therapeutic uses have recently been introduced. Hydrophilic ascorbic acid derivatives such as ascorbyl glycoside have been used not only as antioxidants but also as food and pharmaceutical excipients. In addition to drug solubilization, drug nanoparticle formation was observed using ascorbyl glycoside. Hydrophobic ascorbic acid derivatives such as ascorbyl mono- and di-n-alkyl fatty acid derivatives are used either as drugs or carrier components. Ascorbyl n-alkyl fatty acid derivatives have been formulated as antioxidants or anticancer drugs for nanoparticle formulations such as micelles, microemulsions, and liposomes. ASC-P vesicles called aspasomes are submicron-sized particles that can encapsulate hydrophilic drugs. Several transdermal and injectable formulations of ascorbyl n-alkyl fatty acid derivatives were used, including ascorbyl palmitate.

  14. Ascorbic acid supplementation partially prevents the delayed reproductive development in juvenile male rats exposed to rosuvastatin since prepuberty.

    Science.gov (United States)

    Leite, Gabriel Adan Araújo; Figueiredo, Thamiris Moreira; Sanabria, Marciana; Dias, Ana Flávia Mota Gonçalves; Silva, Patrícia Villela E; Martins Junior, Airton da Cunha; Barbosa Junior, Fernando; Kempinas, Wilma De Grava

    2017-10-01

    Dyslipidemias are occurring earlier in the population due to the increase of obesity and bad eating habits. Rosuvastatin inhibits the enzyme HMG-CoA reductase, decreasing total cholesterol. Ascorbic acid is an important antioxidant compound for male reproductive system. This study aimed to evaluate whether ascorbic acid supplementation may prevent the reproductive damage provoked by rosuvastatin administration at prepuberty. Male pups were distributed into six experimental groups that received saline solution 0.9%, 3 or 10mg/kg/day of rosuvastatin, 150mg/day of ascorbic acid, or 150mg/day of ascorbic acid associated with 3 or 10mg/kg/day of rosuvastatin from post-natal day (PND) 23 until PND53. Rosuvastatin-treated groups showed delayed puberty installation, androgen depletion and impairment on testicular and epididymal morphology. Ascorbic acid partially prevented these reproductive damages. In conclusion, rosuvastatin exposure is a probable risk to reproductive development and ascorbic acid supplementation may be useful to prevent the reproductive impairment of rosuvastatin exposure. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. A flexible micro biofuel cell utilizing hydrogel containing ascorbic acid

    Science.gov (United States)

    Goto, Hideaki; Fukushi, Yudai; Nishioka, Yasushiro

    2014-11-01

    This paper reports on a biofuel cell with a dimension of 13×24 mm2 fabricated on a flexible polyimide substrate. I its porous carbon-coated platinum (Pt) electrodes of 3 mm in width and 10 mm in length were fabricated using photolithography and screen printing techniques. Porous carbon was deposited by screen printing of carbon black ink on the Pt electrode surfaces in order to increase the effective electrode surface area and to absorb more enzymes on the electrode surfaces. It utilizes a solidified ascorbic acid (AA) aqueous solution in an agarose hydrogel to increase the portability. The maximum power and power density for the biofuel cell with the fuel unit containing 100 mM AA were 0.063 μW and 0.21 μW/cm2 at 0.019 V, respectively.

  16. A flexible micro biofuel cell utilizing hydrogel containing ascorbic acid

    International Nuclear Information System (INIS)

    Goto, Hideaki; Fukushi, Yudai; Nishioka, Yasushiro

    2014-01-01

    This paper reports on a biofuel cell with a dimension of 13×24 mm 2 fabricated on a flexible polyimide substrate. I its porous carbon-coated platinum (Pt) electrodes of 3 mm in width and 10 mm in length were fabricated using photolithography and screen printing techniques. Porous carbon was deposited by screen printing of carbon black ink on the Pt electrode surfaces in order to increase the effective electrode surface area and to absorb more enzymes on the electrode surfaces. It utilizes a solidified ascorbic acid (AA) aqueous solution in an agarose hydrogel to increase the portability. The maximum power and power density for the biofuel cell with the fuel unit containing 100 mM AA were 0.063 μW and 0.21 μW/cm 2 at 0.019 V, respectively

  17. Iodometric determination of the ascorbic acid (Vitamin c) content of ...

    African Journals Online (AJOL)

    The ascorbic acid content of seven different fruits –grapefruit, lime, orange, tangerine, banana, pawpaw and pineapple was determined by iodine titration, in order to know which fruit would best supply the ascorbic acid need for the body. Results showed that tangerine had the highest value of ascorbic acid, ...

  18. Higher transcription levels in ascorbic acid biosynthetic and recycling genes were associated with higher ascorbic acid accumulation in blueberry.

    Science.gov (United States)

    Liu, Fenghong; Wang, Lei; Gu, Liang; Zhao, Wei; Su, Hongyan; Cheng, Xianhao

    2015-12-01

    In our preliminary study, the ripe fruits of two highbush blueberry (Vaccinium corymbosum L.) cultivars, cv 'Berkeley' and cv 'Bluecrop', were found to contain different levels of ascorbic acid. However, factors responsible for these differences are still unknown. In the present study, ascorbic acid content in fruits was compared with expression profiles of ascorbic acid biosynthetic and recycling genes between 'Bluecrop' and 'Berkeley' cultivars. The results indicated that the l-galactose pathway was the predominant route of ascorbic acid biosynthesis in blueberry fruits. Moreover, higher expression levels of the ascorbic acid biosynthetic genes GME, GGP, and GLDH, as well as the recycling genes MDHAR and DHAR, were associated with higher ascorbic acid content in 'Bluecrop' compared with 'Berkeley', which indicated that a higher efficiency ascorbic acid biosynthesis and regeneration was likely to be responsible for the higher ascorbic acid accumulation in 'Bluecrop'. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Spectrophotometric determination of copper with ascorbic acid

    Energy Technology Data Exchange (ETDEWEB)

    Majeed, A; Mustafa, M M; Asma, R N; Sareecha, N [Islamia Univ., Bahawalpur (Pakistan). Chemistry Dept.

    1996-06-01

    Copper has been determined spectrophotometrically by using ascorbic acid as a chromagenic reagent. The complex formed in basic medium is measured for its absorbance at 340 n.m. Interference for 23 cations and 9 anions has also been checked. Effect of pH, time, temperature, ammonia, reagent concentration and interferents has been report. (author).

  20. Spectrophotometric determination of copper with ascorbic acid

    International Nuclear Information System (INIS)

    Majeed, A.; Mustafa, M.M.; Asma, R.N.; Sareecha, N.

    1996-01-01

    Copper has been determined spectrophotometrically by using ascorbic acid as a chromagenic reagent. The complex formed in basic medium is measured for its absorbance at 340 n.m. Interference for 23 cations and 9 anions has also been checked. Effect of pH, time, temperature, ammonia, reagent concentration and interferents has been report. (author)

  1. Role of antioxidant scavenging enzymes and extracellular ...

    African Journals Online (AJOL)

    In the present work, we studied the role of antioxidant scavenging enzymes of plant pathogenic bacteria: catalase, ascorbate peroxidase and a virulence factor; extracelluar polysaccharide production in determining the virulence of Xanthomonas oryzae pv. oryzae (Xoo) isolates and its differential reaction to rice cultivars.

  2. sup(99)Tcsup(m)-ascorbate

    International Nuclear Information System (INIS)

    Persson, R.B.R.; Strand, S.E.; White, T.

    1975-01-01

    The sup(99)Tcsup(m)-ascorbate preparation used in this investigation contained FeCl 3 4mN, asorbic acid 110 mM and had an initial pH-value of 7.4 and a final pH-value of 6.8. Studies of the complex-formation were performed with gel-chromatography column-scanning (GCS), which is the analytical method to be preferred for this type of compound, indicated that the complex was formed in two steps. First reduced hydrolyzed sup(99)Tcsup(m) was formed rapidly and the sup(99)Tcsup(m)-ascorbate was formed by a slower reaction (k = 3, 10 -2 min -1 ). The renal uptake of sup(99)Tcsup(m)- was studied in 29 patients with a gamma-camera. The time-course of radio-activity in kidneys, 'tissue background'-areas and in blood suggested that optimal conditions for kidney-imaging were reached 3 to 6 hr after injection. About 20% of the sup(99)Tcsup(m)-ascorbate was bound to plasma-proteins, and only a small fraction to red blood-cells. The disappearance of the sup(99)Tcsup(m)-ascorbate from plasma followed a three-exponential curve: 40% with a half-life of 0.2 hr, 30% with a half-life of 20 hr. The absorbed radiation dose to the kidneys was about 200 (SE +- 60) mrad mCi -1 and to the whole-body 10 (SE +- 3) mrad mCi -1 of administered activity. There was a close correlation (r + 0.98) of the separate renal uptake (dx:(dx +sin)) of sup(99)Tcsup(m)-ascorbate to the separate renal function as determined with 131 I-Hippuran. (author)

  3. The study of ascorbate peroxidase, catalase and peroxidase during in vitro regeneration of Argyrolobium roseum.

    Science.gov (United States)

    Habib, Darima; Chaudhary, Muhammad Fayyaz; Zia, Muhammad

    2014-01-01

    Here, we demonstrate the micropropagation protocol of Argyrolobium roseum (Camb.), an endangered herb exhibiting anti-diabetic and immune-suppressant properties, and antioxidant enzymes pattern is evaluated. Maximum callogenic response (60 %) was observed from leaf explant at 1.0 mg L(-1) 1-nephthalene acetic acid (NAA) and 0.5 mg L(-1) 6-benzyl aminopurine (BA) in Murashige and Skoog (MS) medium using hypocotyl and root explants (48 % each). Addition of AgNO3 and PVP in the culture medium led to an increase in callogenic response up to 86 % from leaf explant and 72 % from hypocotyl and root explants. The best shooting response was observed in the presence of NAA, while maximum shoot length and number of shoots were achieved based on BA-supplemented MS medium. The regenerated shoots were rooted and successfully acclimatized under greenhouse conditions. Catalase and peroxidase enzymes showed ascending pattern during in vitro plant development from seed while ascorbate peroxidase showed descending pattern. Totally reverse response of these enzymes was observed during callus induction from three different explants. During shoot induction, catalase and peroxidase increased at high rate while there was a mild reduction in ascorbate peroxidase activity. Catalase and peroxidase continuously increased; on the other hand, ascorbate peroxidase activity decreased during root development and acclimatization states. The protocol described here can be employed for the mass propagation and genetic transformation of this rare herb. This study also highlights the importance and role of ascorbate peroxidase, catalase, and peroxidase in the establishment of A. roseum in vitro culture through callogenesis and organogenesis.

  4. Role of ascorbic acid in the inhibition of polyphenol oxidase and the prevention of browning in different browning-sensitive Lactuca sativa var. capitata (L.) and Eruca sativa (Mill.) stored as fresh-cut produce.

    Science.gov (United States)

    Landi, Marco; Degl'Innocenti, Elena; Guglielminetti, Lorenzo; Guidi, Lucia

    2013-06-01

    Polyphenol oxidase (PPO) and, to a minor extent, peroxidase (POD) represent the key enzymes involved in enzymatic browning, a negative process induced by cutting fresh-cut produce such as lettuce (Lactuca sativa) and rocket salad (Eruca sativa). Although ascorbic acid is frequently utilised as an anti-browning agent, its mechanism in the prevention of the browning phenomenon is not clearly understood. The activity of PPO and POD and their isoforms in lettuce (a high-browning and low-ascorbic acid species) and rocket salad (a low-browning and high-ascorbic species) was characterised. The kinetic parameters of PPO and in vitro ascorbic acid-PPO inhibition were also investigated. In rocket salad, PPO activity was much lower than that in lettuce and cutting induced an increase in PPO activity only in lettuce. Exogenous ascorbic acid (5 mmol L(-1)) reduced PPO activity by about 90% in lettuce. POD did not appear to be closely related to browning in lettuce. PPO is the main enzyme involved in the browning phenomenon; POD appears to play a minor role. The concentration of endogenous ascorbic acid in rocket salad was related to its low-browning sensitivity after cutting. In lettuce, the addition of ascorbic acid directly inhibited PPO activity. The results suggest that the high ascorbic acid content found in rocket salad plays an effective role in reducing PPO activity. © 2012 Society of Chemical Industry.

  5. Vertically aligned carbon nanotube-sheathed carbon fibers as pristine microelectrodes for selective monitoring of ascorbate in vivo.

    Science.gov (United States)

    Xiang, Ling; Yu, Ping; Hao, Jie; Zhang, Meining; Zhu, Lin; Dai, Liming; Mao, Lanqun

    2014-04-15

    Using as-synthesized vertically aligned carbon nanotube-sheathed carbon fibers (VACNT-CFs) as microelectrodes without any postsynthesis functionalization, we have developed in this study a new method for in vivo monitoring of ascorbate with high selectivity and reproducibility. The VACNT-CFs are formed via pyrolysis of iron phthalocyanine (FePc) on the carbon fiber support. After electrochemical pretreatment in 1.0 M NaOH solution, the pristine VACNT-CF microelectrodes exhibit typical microelectrode behavior with fast electron transfer kinetics for electrochemical oxidation of ascorbate and are useful for selective ascorbate monitoring even with other electroactive species (e.g., dopamine, uric acid, and 5-hydroxytryptamine) coexisting in rat brain. Pristine VACNT-CFs are further demonstrated to be a reliable and stable microelectrode for in vivo recording of the dynamic increase of ascorbate evoked by intracerebral infusion of glutamate. Use of a pristine VACNT-CF microelectrode can effectively avoid any manual electrode modification and is free from person-to-person and/or electrode-to-electrode deviations intrinsically associated with conventional CF electrode fabrication, which often involves electrode surface modification with randomly distributed CNTs or other pretreatments, and hence allows easy fabrication of highly selective, reproducible, and stable microelectrodes even by nonelectrochemists. Thus, this study offers a new and reliable platform for in vivo monitoring of neurochemicals (e.g., ascorbate) to largely facilitate future studies on the neurochemical processes involved in various physiological events.

  6. Ascorbic acid supplementation enhances recovery from ethanol induced inhibition of Leydig cell steroidogenesis than abstention in male guinea pigs.

    Science.gov (United States)

    Radhakrishnakartha, Harikrishnan; Appu, Abhilash Puthuvelvippel; Indira, Madambath

    2014-01-15

    The impact of ascorbic acid supplementation against ethanol induced Leydig cell toxicity was studied in guinea pigs. Male guinea pigs were exposed to ethanol (4g/kgb.wt.) for 90 days. After 90 days, ethanol administration was completely stopped and animals in the ethanol group were divided into abstention group and ascorbic acid supplemented group (25mg/100gb.wt.) and those in control group were maintained as control and control+ascorbic acid group. Ethanol administration reduced the serum testosterone and LH (luteinising hormone) levels and elevated estradiol levels. Cholesterol levels in Leydig cell were increased whereas the mRNA and protein expressions of StAR (steroidogenic acute regulatory) protein, cytochrome P450scc (cytochrome p450side chain cleavage enzyme), 3β-HSD (3β-hydroxysteroid dehydrogenase), 17β-HSD (17β-hydroxysteroid dehydrogenase) and LH receptor were drastically reduced. Administration of ascorbic acid resulted in alteration of all these parameters indicating enhanced recovery from ethanol induced inhibition of Leydig cell steroidogenesis. Although abstention could also reduce the inhibition of steroidogenesis, this was lesser in comparison with ascorbic acid supplemented group. © 2013 Published by Elsevier B.V.

  7. Kinetic and thermodynamic investigation on ascorbate oxidase activity and stability of a Cucurbita maxima extract.

    Science.gov (United States)

    Porto, Tatiana S; Porto, Camila S; Cavalcanti, Maria T H; Filho, José L Lima; Perego, Patrizia; Porto, Ana L F; Converti, Attilio; Pessoa, Adalberto

    2006-01-01

    The kinetic and thermodynamic properties of ascorbate oxidase (AO) activity and stability of a Cucurbita maxima extract were investigated. Activity tests performed at 25 degrees C using initial ascorbic acid concentration in the range 50-750 M allowed estimating the Michaelis constant for this substrate (Km = 126 microM) and the maximum initial rate of ascorbic acid oxidation (A0,max = 1.57 mM min-1). The main thermodynamic parameters of the enzyme reaction (DeltaH* = 10.3 kJ mol-1; DeltaG* = 87.2 kJ mol-1; DeltaS* = -258 J mol-1 K-1) were estimated through activity tests performed at 25-48 C. Within such a temperature range, no decrease in the initial reaction rate was detected. The long-term thermostability of the raw extract was then investigated by means of residual activity tests carried out at 10-70 degrees C, which allowed estimating the thermodynamic parameters of the irreversible enzyme inactivation as well (DeltaH*D = 51.7 kJ mol-1; DeltaG*D = 103 kJ mol-1; S*D = -160 J mol-1 K-1). Taking into account the specific rate of AO inactivation determined at different temperatures, we also estimated the enzyme half-life (1047 min at 10 degrees C and 21.2 min at 70 degrees C) and predicted the integral activity of a continuous system using this enzyme preparation. This work should be considered as a preliminary attempt to characterize the AO activity of a C. maxima extract before its concentration by liquid-liquid extraction techniques.

  8. Expression Patterns of Genes Involved in Ascorbate-Glutathione Cycle in Aphid-Infested Maize (Zea mays L.) Seedlings.

    Science.gov (United States)

    Sytykiewicz, Hubert

    2016-02-23

    Reduced forms of ascorbate (AsA) and glutathione (GSH) are among the most important non-enzymatic foliar antioxidants in maize (Zea mays L.). The survey was aimed to evaluate impact of bird cherry-oat aphid (Rhopalosiphum padi L.) or grain aphid (Sitobion avenae F.) herbivory on expression of genes related to ascorbate-glutathione (AsA-GSH) cycle in seedlings of six maize varieties (Ambrozja, Nana, Tasty Sweet, Touran, Waza, Złota Karłowa), differing in resistance to the cereal aphids. Relative expression of sixteen maize genes encoding isoenzymes of ascorbate peroxidase (APX1, APX2, APX3, APX4, APX5, APX6, APX7), monodehydroascorbate reductase (MDHAR1, MDHAR2, MDHAR3, MDHAR4), dehydroascorbate reductase (DHAR1, DHAR2, DHAR3) and glutathione reductase (GR1, GR2) was quantified. Furthermore, effect of hemipterans' attack on activity of APX, MDHAR, DHAR and GR enzymes, and the content of reduced and oxidized ascorbate and glutathione in maize plants were assessed. Seedling leaves of more resistant Z. mays varieties responded higher elevations in abundance of target transcripts. In addition, earlier and stronger aphid-triggered changes in activity of APX, MDHAR, DHAR and GR enzymes, and greater modulations in amount of the analyzed antioxidative metabolites were detected in foliar tissues of highly resistant Ambrozja genotype in relation to susceptible Tasty Sweet plants.

  9. An efficient synthesis of tetramic acid derivatives with extended conjugation from L-Ascorbic Acid

    Directory of Open Access Journals (Sweden)

    Bisht Surendra S

    2006-12-01

    Full Text Available Abstract Background Tetramic acids with polyenyl substituents are an important class of compounds in medicinal chemistry. Both solid and solution phase syntheses of such molecules have been reported recently. Thiolactomycin, a clinical candidate for treatment of tuberculosis has led to further explorations in this class. We have recently developed an efficient synthesis of tetramic acids derivatives from L- ascorbic acid. In continuation of this work, we have synthesised dienyl tetramic acid derivatives. Results 5,6-O-Isopropylidene-ascorbic acid on reaction with DBU led to the formation of tetronolactonyl allyl alcohol, which on oxidation with pyridinium chlorochromate gave the respective tetranolactonyl allylic aldehydes. Wittig olefination followed by reaction of the resulting tetranolactonyl dienyl esters with different amines resulted in the respective 5-hydroxy lactams. Subsequent dehydration of the hydroxy lactams with p-toluene sulphonic acid afforded the dienyl tetramic acid derivatives. All reactions were performed at ambient temperature and the yields are good. Conclusion An efficient and practical method for the synthesis of dienyl tetramic acid derivatives from inexpensive and easily accessible ascorbic acid has been developed. The compounds bear structural similarities to the tetramic acid based polyenic antibiotics and thus this method offers a new and short route for the synthesis of tetramic acid derivatives of biological significance.

  10. Understanding the degradation of ascorbic acid and glutathione in relation to the levels of oxidative stress biomarkers in broccoli (Brassica oleracea L. italica cv. Bellstar) during storage and mechanical processing.

    Science.gov (United States)

    Raseetha, Siva; Leong, Sze Ying; Burritt, David John; Oey, Indrawati

    2013-06-01

    The purpose of this research was to understand the degradation of ascorbic acid and glutathione content in broccoli florets (Brassica oleracea L. italica cv. Bellstar) during prolonged storage and subsequent mechanical processing. The initial content of total ascorbic acid and glutathione in broccoli florets averaged at 5.18 ± 0.23 and 0.70 ± 0.03 μmol/g fresh weight, respectively. Results showed that the content of ascorbic acid and glutathione in broccoli degraded during storage at 23°C, for at least 4.5-fold after 6 days of storage. On each day of storage, broccoli florets were mechanically processed, but the content of total ascorbic acid and glutathione was not significantly affected. When the mechanically processed broccoli florets were further incubated for up to 6h, the amount of ascorbic acid was greatly reduced as compared to glutathione. To obtain an in-depth understanding on the degradation of ascorbic acid and glutathione, the activity of enzymes involved in plant antioxidative system via ascorbate-glutathione cycle, as a response towards oxidative stress that took place during storage was determined in this study. The content of total ascorbic acid and glutathione in broccoli florets before and after mechanical processing were found to decrease concurrently with the activity of ascorbic acid peroxidase and glutathione reductase over the experimental storage duration. Meanwhile, the effect of oxidative stress on the content of ascorbic acid and glutathione was apparent during the 6h of incubation after mechanical processing. This phenomenon was demonstrated by the level of oxidative stress biomarkers examined, in which the formation of lipid peroxides, protein carbonyls and DNA oxidised products was positively associated with the degradation of total ascorbic acid and glutathione. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. Fate of the synergistic antioxidant system ascorbic acid, lecithin, and tocopherol in mayonnaise : Partition of ascorbic acid

    DEFF Research Database (Denmark)

    Meyer, A.S.; Jacobsen, Charlotte Munch

    1996-01-01

    The distribution of ascorbic acid between the lipid and aqueous phase was investigated in mayonnaises enriched with fish oil containing a synergistic antioxidant mixture of ascorbic acid, lecithin and gamma-tocopherol, i.e., the A/L/T system (Loliger and Saucy 1989). The ascorbic acid was found...... to be located in the aqueous phase indicating that the A/L/T system broke down in mayonnaises. Based on the hypothesis that synergistic antioxidant action between ascorbic acid, lecithin and tocopherol requires that the three components are in close assembly, the results offer an explanation as to why the A...

  12. Toward "stable-on-the-table" enzymes: improving key properties of catalase by covalent conjugation with poly(acrylic acid).

    Science.gov (United States)

    Riccardi, Caterina M; Cole, Kyle S; Benson, Kyle R; Ward, Jessamyn R; Bassett, Kayla M; Zhang, Yiren; Zore, Omkar V; Stromer, Bobbi; Kasi, Rajeswari M; Kumar, Challa V

    2014-08-20

    Several key properties of catalase such as thermal stability, resistance to protease degradation, and resistance to ascorbate inhibition were improved, while retaining its structure and activity, by conjugation to poly(acrylic acid) (PAA, Mw 8000) via carbodiimide chemistry where the amine groups on the protein are appended to the carboxyl groups of the polymer. Catalase conjugation was examined at three different pH values (pH 5.0, 6.0, and 7.0) and at three distinct mole ratios (1:100, 1:500, and 1:1000) of catalase to PAA at each reaction pH. The corresponding products are labeled as Cat-PAA(x)-y, where x is the protein to polymer mole ratio and y is the pH used for the synthesis. The coupling reaction consumed about 60-70% of the primary amines on the catalase; all samples were completely water-soluble and formed nanogels, as evidenced by gel electrophoresis and electron microscopy. The UV circular dichroism (CD) spectra indicated substantial retention of protein secondary structure for all samples, which increased to 100% with increasing pH of the synthesis and polymer mole fraction. Soret CD bands of all samples indicated loss of ∼50% of band intensities, independent of the reaction pH. Catalytic activities of the conjugates increased with increasing synthesis pH, where 55-80% and 90-100% activity was retained for all samples synthesized at pH 5.0 and pH 7.0, respectively, and the Km or Vmax values of Cat-PAA(100)-7 did not differ significantly from those of the free enzyme. All conjugates synthesized at pH 7.0 were thermally stable even when heated to ∼85-90 °C, while native catalase denatured between 55 and 65 °C. All conjugates retained 40-90% of their original activities even after storing for 10 weeks at 8 °C, while unmodified catalase lost all of its activity within 2 weeks, under similar storage conditions. Interestingly, PAA surrounding catalase limited access to the enzyme from large molecules like proteases and significantly increased

  13. Electrocatalytic Activity of Carbonized Nanostructured Polyanilines for Oxidation Reactions: Sensing of Nitrite Ions and Ascorbic Acid

    International Nuclear Information System (INIS)

    Micić, Darko; Šljukić, Biljana; Zujovic, Zoran; Travas-Sejdic, Jadranka; Ćirić-Marjanović, Gordana

    2014-01-01

    Highlights: • Carbonized PANIs prepared from various nanostructured PANI precursors • Electroanalytical performances of carbonized PANIs evaluated using voltammetry • Study of carbonized PANIs physico-chemical properties related to electroactivity • The lowest over-potential for NO 2 − oxidation at c-PANI (+0.87 V vs. SCE) • The lowest over-potential for ascorbic acid oxidation at both c-PANI and c-PANI-SSA - Abstract: A comparative study of the electrocatalytic activity of nitrogen-containing carbon nanomaterials, prepared by the carbonization of nanostructured polyaniline (PANI) salts, for the electrooxidation reactions is presented. Nanostructured PANI salts were synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate in an aqueous solution in the presence of 5-sulfosalicylic acid (PANI-SSA), 3,5-dinitrosalicylic acid (PANI-DNSA) as well as without added acid (PANI), and subsequently carbonized to c-PANI-SSA, c-PANI-DNSA and c-PANI, respectively. Glassy carbon tip was modified with nanostructured c-PANIs and used for the investigation of sensing of nitrite and ascorbic acid in aqueous solutions as model analytes by linear sweep voltammetry. All three types of the investigated c-PANIs gave excellent response to the nitrite ions and ascorbic acid electrooxidation. The lowest peak potential for nitrite ion oxidation exhibited c-PANI (+0.87 V vs. SCE), and for ascorbic acid oxidation both c-PANI and c-PANI-SSA (ca. + 0.13 V vs. SCE). Electrochemical data were correlated with structural and textural data obtained by Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, elemental and nitrogen sorption analysis

  14. Pancreatic Enzymes

    Science.gov (United States)

    ... Contact Us DONATE NOW GENERAL DONATION PURPLESTRIDE Pancreatic enzymes Home Facing Pancreatic Cancer Living with Pancreatic Cancer ... and see a registered dietitian. What are pancreatic enzymes? Pancreatic enzymes help break down fats, proteins and ...

  15. Reversal of alcohol induced testicular hyperlipidemia by supplementation of ascorbic acid and its comparison with abstention in male guinea pigs.

    Science.gov (United States)

    Radhakrishnakartha, Harikrishnan; Appu, Abhilash Puthuvelvippel; Madambath, Indira

    2014-02-01

    Chronic ethanol exposure causes hyperlipidemia. The present study was designed to investigate the impact of ascorbic acid supplementation on ethanol induced hyperlipidemia in testis and to compare it with that of abstinence from taking alcohol. Thirty-six male guinea pigs were divided into two groups and were maintained for 90 days as follows (1) control (C) (2) ethanol treated group (E) (4 g/kg body wt/day). Ethanol was administered for 90 days and on 90th day, alanine amino transaminase (ALT), aspartate amino transaminase (AST) and γ-glutamyltransferase (GGT) in serum was assayed. The animals in the ethanol group were further divided into an ascorbic acid supplemented group (25 mg/100 g body wt/day) (E+AA) and an ethanol abstention group (EAG) and those in the control group were divided into a control group and a control+ascorbic acid group (C+AA). There was significant increase in levels of testicular cholesterol, free fatty acid, phospholipids and triglycerides in the ethanol group. There was also a significant increase in the activity of HMG CoA reductase and decrease in activity of testicular glucose-6-phosphate dehydrogenase (G6PDH) and malic enzyme in ethanol-ingested animals that further led to decreased levels of serum testosterone. Alcohol administration also enhanced the activity of testicular alcohol dehydrogenase (ADH). Ascorbic acid supplementation and abstention altered all these parameters induced by chronic alcohol administration. Histological studies were also in line with the above results. Ascorbic acid was able to reinstate the cholesterol homeostasis in testis which could have further restored the testicular steroidogenesis. The present study demonstrated that ascorbic acid is effective in reducing the hyperlipidemia induced by chronic alcohol administration and produced a better recovery than abstention.

  16. Lipid peroxidation and ascorbic acid levels in Nigeria children with ...

    African Journals Online (AJOL)

    This study was undertaken to establish data on the roles of lipid peroxidation and ascorbic acid in the pathology of malaria in Nigeria children. We measured the levels of malondialdehyde (MDA), a marker of lipid peroxidation and ascorbic acid in the plasma of 406 parasitaemic and 212 non-parasitaemic Nigerian children.

  17. Oral Metformin-Ascorbic Acid Co-Administration Ameliorates Alcohol ...

    African Journals Online (AJOL)

    Oral Metformin-Ascorbic Acid Co-Administration Ameliorates Alcohol-Induced Hepatotoxicity In Rats. ... Nigerian Quarterly Journal of Hospital Medicine ... the present in vivo animal study was to determine whether metformin-ascorbic acid co-administration also prevents alcoholic hepatotoxicity in chronic alcohol exposure.

  18. Cloning and analysis of the ascorbate peroxidase gene promoter ...

    African Journals Online (AJOL)

    Ascorbate peroxidase (APX) is known to catalyze the reduction of H2O2 to water and enhance plants' tolerance in stress environment. An ascorbate peroxidase protein (BnAPX) was previously isolated from Brassica napus in our laboratory and it was located in the chloroplast. In order to clarify the physiological function of ...

  19. Isolation of an ascorbate peroxidase in Brassica napus and analysis ...

    African Journals Online (AJOL)

    USER

    2010-04-05

    Apr 5, 2010 ... domain; APX, ascorbate peroxidase; Bn-APX, Brassica napus ascorbate ... Brassica napus, which is widely grown as the oilseed crop of rape or canola, .... grew on the SD-Leu-Trp-His-Ade medium and were verified by PCR.

  20. Modelling of thermal degradation kinetics of ascorbic acid in ...

    African Journals Online (AJOL)

    Ascorbic acid (vitamin C) loss in thermally treated pawpaw and potato was modelled mathematically. Isothermal experiments in the temperature range of 50 -80 oC for the drying of pawpaw and 60 -100 oC for the blanch-drying of potato were utilized to determine the kinetics of ascorbic acid loss in both fruit and vegetable.

  1. Effect of ascorbic acid supplementation level to diets of indigenous ...

    African Journals Online (AJOL)

    All the birds were offered the same grower feed and fresh water ad libitum. Indigenous Venda hens supplemented with ascorbic acid produced chicks with improved (P<0.05) feed intake, feed conversion ratio, growth rate and live weight at 7 weeks of age. However, ascorbic acid supplementation to the diets of indigenous ...

  2. Gamma radiolysis of aqueous solution of ascorbic acid

    International Nuclear Information System (INIS)

    Loyola V, V.M.; Azamer B, J.A.; Laviada C, A.; Luna V, P.

    1977-01-01

    A preliminary study of the gamma radiolysis of a 1.13 x 10 -4 Maqueous solution of ascorbic acid is presented. It was found that dehydroascorbic acid was the principal product at doses of about 75 Krad. An increase in the dehydroascorbic acid concentration rangins from 5 to 40% was obtained, these values depend mainly on the initial ascorbic acid concentration. (author)

  3. Effect of supplemental Ascorbic acid and disturbance stress on the ...

    African Journals Online (AJOL)

    Effect of supplemental Ascorbic acid and disturbance stress on the performance of broiler chickens. ... Nigerian Journal of Animal Production ... Results showed that there were no significant interactions between dietary ascorbic acid supplementation and disturbance stress levels on any of the performance data considered.

  4. Low Ascorbic Acid in the vtc-1 Mutant of Arabidopsis Is Associated with Decreased Growth and Intracellular Redistribution of the Antioxidant System1

    Science.gov (United States)

    Veljovic-Jovanovic, Sonja D.; Pignocchi, Cristina; Noctor, Graham; Foyer, Christine H.

    2001-01-01

    Ascorbic acid has numerous and diverse roles in plant metabolism. We have used the vtc-1 mutant of Arabidopsis, which is deficient in ascorbate biosynthesis, to investigate the role of ascorbate concentration in growth, regulation of photosynthesis, and control of the partitioning of antioxidative enyzmes. The mutant possessed 70% less ascorbate in the leaves compared with the wild type. This lesion was associated with a slight increase in total glutathione but no change in the redox state of either ascorbate or glutathione. In vtc-1, total ascorbate in the apoplast was decreased to 23% of the wild-type value. The mutant displayed much slower shoot growth than the wild type when grown in air or at high CO2 (3 mL L−1), where oxidative stress is diminished. Leaves were smaller, and shoot fresh weight and dry weight were lower in the mutant. No significant differences in the light saturation curves for CO2 assimilation were found in air or at high CO2, suggesting that the effect on growth was not due to decreased photosynthetic capacity in the mutant. Analysis of chlorophyll a fluorescence quenching revealed only a slight effect on non-photochemical energy dissipation. Hydrogen peroxide contents were similar in the leaves of the vtc-1 mutant and the wild type. Total leaf peroxidase activity was increased in the mutant and compartment-specific differences in ascorbate peroxidase (APX) activity were observed. In agreement with the measurements of enzyme activity, the expression of cytosolic APX was increased, whereas that for chloroplast APX isoforms was either unchanged or slightly decreased. These data implicate ascorbate concentration in the regulation of the compartmentalization of the antioxidant system in Arabidopsis. PMID:11598218

  5. Attenuation of abnormalities in the lipid metabolism during experimental myocardial infarction induced by isoproterenol in rats: beneficial effect of ferulic acid and ascorbic acid.

    Science.gov (United States)

    Yogeeta, Surinder Kumar; Hanumantra, Rao Balaji Raghavendran; Gnanapragasam, Arunachalam; Senthilkumar, Subramanian; Subhashini, Rajakannu; Devaki, Thiruvengadam

    2006-05-01

    The present study aims at evaluating the effect of the combination of ferulic acid and ascorbic acid on isoproterenol-induced abnormalities in lipid metabolism. The rats were divided into eight groups: Control, isoproterenol, ferulic acid alone, ascorbic acid alone, ferulic acid+ascorbic acid, ferulic acid+isoproterenol, ascorbic acid+isoproterenol and ferulic acid+ascorbic acid+isoproterenol. Ferulic acid (20 mg/kg b.w.t.) and ascorbic acid (80 mg/kg b.w.t.) both alone and in combination was administered orally for 6 days and on the fifth and the sixth day, isoproterenol (150 mg/kg b.w.t.) was injected intraperitoneally to induce myocardial injury to rats. Induction of rats with isoproterenol resulted in a significant increase in the levels of triglycerides, total cholesterol, free fatty acids, free and ester cholesterol in both serum and cardiac tissue. A rise in the levels of phospholipids, lipid peroxides, low density lipoprotein and very low density lipoprotein-cholesterol was also observed in the serum of isoproterenol-intoxicated rats. Further, a decrease in the level of high density lipoprotein in serum and in the phospholipid levels, in the heart of isoproterenol-intoxicated rats was observed, which was paralleled by abnormal activities of lipid metabolizing enzymes: total lipase, cholesterol ester synthase, lipoprotein lipase and lecithin: cholesterol acyl transferase. Pre-cotreatment with the combination of ferulic acid and ascorbic acid significantly attenuated these alterations and restored the levels to near normal when compared to individual treatment groups. Histopathological observations were also in correlation with the biochemical parameters. These findings indicate the synergistic protective effect of ferulic acid and ascorbic acid on isoproterenol-induced abnormalities in lipid metabolism.

  6. Formation of an ascorbate-apatite composite layer on titanium

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Atsuo [National Institute of Advanced Industrial Science and Technology (AIST), Institute for Human Science and Biomedical Engineering, Central 6, Higashi 1-1-1, Tsukuba, Ibaraki 305-8566 (Japan); Sogo, Yu [National Institute of Advanced Industrial Science and Technology (AIST), Institute for Human Science and Biomedical Engineering, Central 6, Higashi 1-1-1, Tsukuba, Ibaraki 305-8566 (Japan); Ebihara, Yuko [School of Science and Technology, Waseda University, 3-4-1 Okubo, Sinjuku-ku, Tokyo 169-8050 (Japan); Onoguchi, Masahiro [School of Science and Technology, Waseda University, 3-4-1 Okubo, Sinjuku-ku, Tokyo 169-8050 (Japan); Oyane, Ayako [National Institute of Advanced Industrial Science and Technology (AIST), Nanotechnology Research Institute, Central 4, Higashi 1-1-1, Tsukuba, Ibaraki 305-8562 (Japan); Ichinose, Noboru [School of Science and Technology, Waseda University, 3-4-1 Okubo, Sinjuku-ku, Tokyo 169-8050 (Japan)

    2007-09-15

    An ascorbate-apatite composite layer was successfully formed on NaOH- and heat-treated titanium by coprecipitating L-ascorbic acid phosphate and low-crystalline apatite in a supersaturated calcium phosphate solution at 37 {sup 0}C for 48 h. The supersaturated calcium phosphate solutions used have chemical compositions attainable by mixing infusion fluids officially approved for clinical use. The amount of immobilized L-ascorbic acid phosphate ranged from 1.0 to 2.3 {mu}g mm{sup -2}, which is most likely to be sufficient for the in vitro osteogenic differentiation of mesenchymal stem cells on titanium. Since ascorbate is important for the collagen synthesis and subsequent osteogenesis of mesenchymal stem cells, titanium coated with the ascorbate-apatite composite layer would be useful as a scaffold in bone tissue engineering and as a bone substitute.

  7. Formation of an ascorbate-apatite composite layer on titanium

    International Nuclear Information System (INIS)

    Ito, Atsuo; Sogo, Yu; Ebihara, Yuko; Onoguchi, Masahiro; Oyane, Ayako; Ichinose, Noboru

    2007-01-01

    An ascorbate-apatite composite layer was successfully formed on NaOH- and heat-treated titanium by coprecipitating L-ascorbic acid phosphate and low-crystalline apatite in a supersaturated calcium phosphate solution at 37 0 C for 48 h. The supersaturated calcium phosphate solutions used have chemical compositions attainable by mixing infusion fluids officially approved for clinical use. The amount of immobilized L-ascorbic acid phosphate ranged from 1.0 to 2.3 μg mm -2 , which is most likely to be sufficient for the in vitro osteogenic differentiation of mesenchymal stem cells on titanium. Since ascorbate is important for the collagen synthesis and subsequent osteogenesis of mesenchymal stem cells, titanium coated with the ascorbate-apatite composite layer would be useful as a scaffold in bone tissue engineering and as a bone substitute

  8. Radioprotective effects of ascorbic acid in barley seeds

    Energy Technology Data Exchange (ETDEWEB)

    Conger, B V

    1975-01-01

    Experiments were conducted to test the radioprotective effects of a naturally occurring reducing agent, ascorbic acid, on seeds (caryopses) of barley, Hordeum vulgare L. emend Lam. Seeds were soaked either before or after ..gamma.. or fission neutron irradiation in distilled water or ascorbic acid solutions ranging in concentration from 0.01 to 1.00 M. Results are reported as percentage germination, seedling height, seedling growth reduction, and (in one experiment) percent of cells with chromosome aberrations. As evidenced by both reduced germination and seedling growth, ascorbic acid was toxic when seeds were soaked for 1 hr at ambient temperature prior to irradiation and then planted immediately. When seeds were soaked in ascorbic acid before irradiation and soaked after irradiation in air-bubbled water at 0/sup 0/C for 18 hr, the toxicity disappeared, and a protective effect (which increased with increasing ascorbic acid concentration) was observed for ..gamma.. and, to a lesser extent, for neutron irradiation. Additional studies suggested that the protective effect was related to reduced hydration of the embryos of seeds soaked in ascorbic acid. Also, no radioprotective effect was observed when seeds were presoaked for 2 or 16 hr in 0.01 M ascorbic acid solutions buffered at pH 3 or pH 7. A protective effect was observed for seeds of 1.5 percent water content soaked after irradiation in an oxygen-bubbled ascorbic acid solution of 0.5 M but was not observed for seeds soaked in nitrogen-bubbled ascorbic acid. The protective effect against oxygen-dependent damage may be a result of interaction of ascorbic acid with radiation-induced free radicals.

  9. L-Ascorbic acid metabolism during fruit development in an ascorbate-rich fruit crop chestnut rose (Rosa roxburghii Tratt).

    Science.gov (United States)

    Huang, Ming; Xu, Qiang; Deng, Xiu-Xin

    2014-09-01

    Chestnut rose (Rosa roxburghii Tratt) is a fruit crop that contains unusually high levels of l-ascorbic acid (AsA; ∼1300 mg 100g(-1) FW). To explore the mechanisms underlying AsA metabolism, we investigated the distribution and abundance of AsA during fruit development. We also analyzed gene expression patterns, enzyme activities, and content of metabolites related to AsA biosynthesis and recycling. AsA first accumulated during late fruit development and continued to accumulate during ripening, with the highest accumulation rate near fruit maturity. The redox state of AsA in fruit was also enhanced during late fruit development, while leaf and other tissues had much lower levels of AsA and the redox state of AsA was lower. In mature fruit, AsA was mainly distributed in the cytoplasm of the mesocarp. Correlation analysis suggested that the gene expression patterns, enzyme activities, and related metabolite concentrations involved in the l-galactose pathway showed relatively high correlations with the accumulation rate of AsA. The gene expression pattern and activity of dehydroascorbate reductase (DHAR, EC 1.8.5.1) correlated strongly with AsA concentration, possibly indicating the crucial role of DHAR in the accumulation of high levels of AsA in chestnut rose fruit. Over expression of DHAR in Arabidopsis significantly increased the reduced AsA content and redox state. This was more effective than over expression of the l-galactose pathway gene GDP-d-mannose-3,5-epimerase (EC 5.1.3.18). These findings will enhance understanding of the molecular mechanisms regulating accumulation of AsA in chestnut rose. Copyright © 2014 Elsevier GmbH. All rights reserved.

  10. Natural resistance to ascorbic acid induced oxidative stress is mainly mediated by catalase activity in human cancer cells and catalase-silencing sensitizes to oxidative stress

    Directory of Open Access Journals (Sweden)

    Klingelhoeffer Christoph

    2012-05-01

    Full Text Available Abstract Background Ascorbic acid demonstrates a cytotoxic effect by generating hydrogen peroxide, a reactive oxygen species (ROS involved in oxidative cell stress. A panel of eleven human cancer cell lines, glioblastoma and carcinoma, were exposed to serial dilutions of ascorbic acid (5-100 mmol/L. The purpose of this study was to analyse the impact of catalase, an important hydrogen peroxide-detoxifying enzyme, on the resistance of cancer cells to ascorbic acid mediated oxidative stress. Methods Effective concentration (EC50 values, which indicate the concentration of ascorbic acid that reduced the number of viable cells by 50%, were detected with the crystal violet assay. The level of intracellular catalase protein and enzyme activity was determined. Expression of catalase was silenced by catalase-specific short hairpin RNA (sh-RNA in BT-20 breast carcinoma cells. Oxidative cell stress induced apoptosis was measured by a caspase luminescent assay. Results The tested human cancer cell lines demonstrated obvious differences in their resistance to ascorbic acid mediated oxidative cell stress. Forty-five percent of the cell lines had an EC50 > 20 mmol/L and fifty-five percent had an EC50 50 of 2.6–5.5 mmol/L, glioblastoma cells were the most susceptible cancer cell lines analysed in this study. A correlation between catalase activity and the susceptibility to ascorbic acid was observed. To study the possible protective role of catalase on the resistance of cancer cells to oxidative cell stress, the expression of catalase in the breast carcinoma cell line BT-20, which cells were highly resistant to the exposure to ascorbic acid (EC50: 94,9 mmol/L, was silenced with specific sh-RNA. The effect was that catalase-silenced BT-20 cells (BT-20 KD-CAT became more susceptible to high concentrations of ascorbic acid (50 and 100 mmol/L. Conclusions Fifty-five percent of the human cancer cell lines tested were unable to protect themselves

  11. Polarographic measurement of ascorbate washout in isolated perfused rabbit hearts

    International Nuclear Information System (INIS)

    Arts, T.; Kuikka, J.T.; Reneman, R.S.; Bassingthwaighte, J.B.

    1985-01-01

    To study the myocardial washout of ascorbate, the applicability of polarographic detection of ascorbate ions by a platinum electrode (sensitive area 0.03 mm2) was investigated, in both a calibration setup (sampling flow along the electrode: 100 microliter X s-1) and isolated, retrogradely perfused rabbit hearts. In the calibration setup at pH 7.4, the sensitivity of the electrode was 70 microA/mol. This sensitivity increased moderately with increasing pH (13%/unit pH) and increasing sampling flow rate (14% at an increase from 100 to 150 microliter X s-1). In the isolated hearts, ascorbate infused into the aorta was detected in a right ventricular drain by the electrode as well as by the use of 14 C-labeled ascorbate. Both recorded time courses were similar except for a scaling factor dependent on flow velocity. During continuous infusion the arteriovenous difference of ascorbate was 2 +/- 2% (SD), indicating a relatively low consumption of ascorbate by the isolated heart. The authors conclude that polarographic measurement of ascorbate in the coronary effluent of an isolated rabbit heart can be performed on-line and relatively easily

  12. Diurnal gradual heat stress affects antioxidant enzymes, proline ...

    African Journals Online (AJOL)

    USER

    2010-02-15

    Feb 15, 2010 ... to non-toxic levels by catabolizing it to water and oxygen. (Mittler ... within hours, unlike drought and salinity stresses. Therefore ... mechanism of response of cotton to elevated ..... Copper enzymes in isolated chloroplasts; polyphenol- .... transcription factor-dependent expression and activity of ascorbate.

  13. Extraction of ascorbate oxidase from Cucurbita maxima by continuous process in perforated rotating disc contactor using aqueous two-phase systems.

    Science.gov (United States)

    Porto, T S; Marques, P P; Porto, C S; Moreira, K A; Lima-Filho, J L; Converti, A; Pessoa, A; Porto, A L F

    2010-02-01

    The ascorbate oxidase is the enzyme used to determine the content of ascorbic acid in the pharmaceutical and food industries and clinics analyses. The techniques currently used for the purification of this enzyme raise its production cost. Thus, the development of alternative processes and with the potential to reduce costs is interesting. The application of aqueous two-phase system is proposed as an alternative to purification because it enables good separation of biomolecules. The objective of this study was to determine the conditions to continuously pre-purify the enzyme ascorbate oxidase by an aqueous two-phase system (PEG/citrate) using rotating column provided with perforated discs. Under the best conditions (20,000 g/mol PEG molar mass, 10% PEG concentration, and 25% citrate concentration), the system showed satisfactory results (partition coefficient, 3.35; separation efficiency, 54.98%; and purification factor, 1.46) and proved suitable for the pre-purification of ascorbate oxidase in continuous process.

  14. All-solid-state potentiometric sensors for ascorbic acid by using a screen-printed compatible solid contact

    International Nuclear Information System (INIS)

    Veltsistas, Panayotis G.; Prodromidis, Mamas I.; Efstathiou, Constantinos

    2004-01-01

    The development of all-solid-state potentiometric ion selective electrodes for monitoring of ascorbic acid, by using a screen-printed compatible solid contact is described. The applied methodology is based on the use of PVC membrane modified with some firstly-tested ionophores (triphenyltin(IV)chloride, triphenyltin(IV)hydroxide and palmitoyl-L-ascorbic acid) and a novel one synthesized in our laboratory (dibutyltin(IV) diascorbate). Synthesis protocol and some preliminary identification studies are given. A conductive graphite-based polymer thick film ink was used as an internal solid contact between the graphite electrode and the PVC membrane. The presence and the nature of the solid contact (plain or doped with lanthanum 2,6-dichlorophenolindophenol (DCPI)) seem to enhance the analytical performance of the electrodes in terms of sensitivity, dynamic range, and response time. The analytical performance of the constructed electrodes was evaluated with potentiometry, constant-current chronopotentiometry and electrochemical impedance spectroscopy (EIS). The interference effect of various compounds was also tested. The potential response of the optimized Ph 3 SnCl-based electrode was linear against ascorbic acid concentration range 0.005-5.0 mM. The applicability of the proposed sensors in real samples was also tested. The detection limit was 0.002 mM ascorbic acid (50 mM phosphate, pH 5 in 50 mM KCl). The slope of the electrodes was super-Nernstian and pH dependent, indicating a mechanism involving a combination of charge transfer and ion exchange processes. Fabrication of screen-printed ascorbate ISEs has also been demonstrated

  15. ASCORBIC ACID STATUS IN PREGNANCY AND POSTPARTUM WOMEN IN ENUGU, SOUTH-EAST, NIGERIA: ARE VITAMIN SUPPLEMENTS SUFFICIENT?

    Directory of Open Access Journals (Sweden)

    2017-01-01

    Full Text Available Pregnancy has been shown to be a period of stress, during which the nutritional needs of the foetus is dependent on that of the mother. It is also a condition exhibiting increased susceptibility to oxidative stress, leading to potential damage. Ascorbic acid is a strong antioxidant as well as a reducing agent and is increasingly utilized to normalize the pro-oxidant - antioxidant balance during pregnancy. Since ascorbic acid cannot be synthesized by the body, leading to total dependence on exogenous supply in diets, there is need to evaluate the level of the vitamin in pregnant women and determine their predisposition or otherwise to avitaminosis C. Ascorbic acid levels of 60 apparently healthy pregnant women, aged between 20-40 years old and attending the antenatal clinic at the UNTH, Enugu, 60 age-matched women in their postpartum and 60 age-matched non-pregnant women (controls were assayed using the 2,4-dinitrophenyl hydrazine method. The serum ascorbic acid levels were significantly lower (P and lt;0.05 in pregnant women, showing a steady decline with gestational age increase. There were statistically significant decreases (P and lt;0.05 in the second and third trimesters whereas a significant increase (P and lt;0.05 was observed in the postpartum period, when compared to the controls. The serum levels of ascorbic acid were decreased significantly as pregnancy progresses; in spite of the supplements given Significant increases in the postpartum period may be attributed to the absence of oxidative stress and recovery from stress. Additional supplementation and increased dietary intake should be encouraged in pregnant women.

  16. Synthesis of microspheres of triuranium octaoxide by simultaneous water and nitrate extraction from ascorbate-uranyl sols

    International Nuclear Information System (INIS)

    Brykala, M.; Deptula, A.; Rogowski, M.; Lada, W.; Olczak, T.; Wawszczak, D.; Smolinski, T.; Wojtowicz, P.; Modolo, G.

    2014-01-01

    A new method for synthesis of uranium oxide microspheres (diameter <100 μm) has been developed. It is a variant of our patented Complex Sol-Gel Process, which has been used to synthesize high-quality powders of a wide variety of complex oxides. Starting uranyl-nitrate-ascorbate sols were prepared by addition of ascorbic acid to uranyl nitrate hexahydrate solution and alkalizing by aqueous ammonium hydroxide and then emulsified in 2-ethylhexanol-1 containing 1v/o SPAN-80. Drops of emulsion were firstly gelled by extraction of water by the solvent. Destruction of the microspheres during thermal treatment, owing to highly reactive components in the gels, requires modification of the gelation step by Double Extraction Process-simultaneously extraction of water and nitrates using Primene JMT, which completely eliminates these problem. Final step was calcination in air of obtained microspheres of gels to triuranium octaoxide. (author)

  17. Toxicity of nickel and silver to Nostoc muscorum: interaction with ascorbic acid, glutathione, and sulfur-containing amino acids.

    Science.gov (United States)

    Rai, L C; Raizada, M

    1987-08-01

    Exposure of Nostoc muscorum to different concentrations of Ni and Ag brought about reduction in growth, carbon fixation, heterocyst production, and nitrogenase activity and increase in the loss of ions (K+, Na+). In an attempt to ameliorate the toxicity of test metals by ascorbic acid, glutathione, and sulfur-containing amino acids (L-cysteine and L-methionine), it was found that the level of protection by ascorbic acid and glutathione was more for Ag than Ni. However, metal-induced inhibition of growth and carbon fixation was equally ameliorated by methionine. But the level of protection by cysteine was quite different, i.e., 27% for Ni and 22% for Ag. Protection of metal toxicity in N. muscorum by amino acids lends further support to self-detoxifying ability of cyanobacteria because they are known to synthesize all essential amino acids.

  18. Analysis of redox relationships in the plant cell cycle: determinations of ascorbate, glutathione and poly (ADPribose)polymerase (PARP) in plant cell cultures.

    Science.gov (United States)

    Foyer, Christine H; Pellny, Till K; Locato, Vittoria; De Gara, Laura

    2008-01-01

    Reactive oxygen species (ROS) and low molecular weight antioxidants, such as glutathione and ascorbate, are powerful signaling molecules that participate in the control of plant growth and development, and modulate progression through the mitotic cell cycle. Enhanced reactive oxygen species accumulation or low levels of ascorbate or glutathione cause the cell cycle to arrest and halt progression especially through the G1 checkpoint. Plant cell suspension cultures have proved to be particularly useful tools for the study of cell cycle regulation. Here we provide effective and accurate methods for the measurement of changes in the cellular ascorbate and glutathione pools and the activities of related enzymes such poly (ADP-ribose) polymerase during mitosis and cell expansion, particularly in cell suspension cultures. These methods can be used in studies seeking to improve current understanding of the roles of redox controls on cell division and cell expansion.

  19. Synthesis of L-ascorbic acid in the phloem

    Directory of Open Access Journals (Sweden)

    Haupt Sophie

    2003-11-01

    Full Text Available Abstract Background Although plants are the main source of vitamin C in the human diet, we still have a limited understanding of how plants synthesise L-ascorbic acid (AsA and what regulates its concentration in different plant tissues. In particular, the enormous variability in the vitamin C content of storage organs from different plants remains unexplained. Possible sources of AsA in plant storage organs include in situ synthesis and long-distance transport of AsA synthesised in other tissues via the phloem. In this paper we examine a third possibility, that of synthesis within the phloem. Results We provide evidence for the presence of AsA in the phloem sap of a wide range of crop species using aphid stylectomy and histochemical approaches. The activity of almost all the enzymes of the primary AsA biosynthetic pathway were detected in phloem-rich vascular exudates from Cucurbita pepo fruits and AsA biosynthesis was demonstrated in isolated phloem strands from Apium graveolens petioles incubated with a range of precursors (D-glucose, D-mannose, L-galactose and L-galactono-1,4-lactone. Phloem uptake of D-[U-14C]mannose and L-[1-14C]galactose (intermediates of the AsA biosynthetic pathway as well as L-[1-14C]AsA and L-[1-14C]DHA, was observed in Nicotiana benthamiana leaf discs. Conclusions We present the novel finding that active AsA biosynthesis occurs in the phloem. This process must now be considered in the context of mechanisms implicated in whole plant AsA distribution. This work should provoke studies aimed at elucidation of the in vivo substrates for phloem AsA biosynthesis and its contribution to AsA accumulation in plant storage organs.

  20. Effect of 10% sodium ascorbate on Streptococcus mutans ...

    African Journals Online (AJOL)

    USER

    2010-08-16

    Aug 16, 2010 ... After sterilization of the intact enamel surfaces with UV light, the specimens .... the bleaching agent and sodium ascorbate has led to a maximum amount of .... Radcliffe CE, Lamp R, Blinkhorn AS, Drucker DB (2003). Effect of.

  1. Effects of Ascorbic Acid on Reproductive Functions of Male Wistar ...

    African Journals Online (AJOL)

    In conclusion, ascorbic acid supplement may suppress nicotine toxic effects on reproductive functions in male rats. ... et al., 2007). Nicotine is rapidly absorbed by the brain .... difference (LSD) test. p<0.05 was considered significant. Statistical ...

  2. Radiation protection by ascorbic acid in sodium alginate solutions

    Energy Technology Data Exchange (ETDEWEB)

    Aliste, A.J.; Mastro, N.L. Del [Center of Radiation Technology, IPEN/CNEN/SP, University City, 05508-000 Sao Paulo (Brazil)]. E-mail: ajaliste@ipen.br

    2004-07-01

    Alginates are gelling hydrocolloids extracted from brown seaweed used widely in the nourishing and pharmaceutical industries. As alginic acid gellification retard food entrance in the stomach alginate is an additive used in diets. The objective of this work was to study the protective action of the ascorbic acid in alginate solutions against the action of {sup 60} Co gamma radiation. One % (w/v) solutions of alginate had been used and concentrations of ascorbic acid varied from 0 to 2.5% (w/v). The solutions were irradiated with doses up to 10 kGy. Viscosity/dose relationship and the p H of the solutions at 25 Centigrade were determined. Ascorbic acid behaved as an antioxidant against radiation oxidative shock in this model system of an irradiated viscous solution. Besides its radiation protective role on alginate solutions ascorbic acid promoted a viscosity increase in the range of concentrations employed. (Author)

  3. Lead induced dyslipidemia: The comparative effects of ascorbate ...

    African Journals Online (AJOL)

    R.N. UGBAJA

    2013-04-10

    Apr 10, 2013 ... Key words: Ascorbate, chelating agents, dyslipidemia, lead exposure, plumbism. .... elements like iron, zinc, calcium and a host of other divalent elements in ..... cholesterol synthesis and transport pathways may be adversely ...

  4. Effects of Ascorbic Acid on Reproductive Functions of Male Wistar ...

    African Journals Online (AJOL)

    Effects of Ascorbic Acid on Reproductive Functions of Male Wistar Rats Exposed to Nicotine. ... smoke, and its effects on male reproductive system and fertility are well documented. ... The drugs were orally administered for thirty-five days.

  5. Selective response of dopamine in the presence of ascorbic acid ...

    African Journals Online (AJOL)

    Selective response of dopamine in the presence of ascorbic acid and uric acid at gold nanoparticles and multi-walled carbon nanotubes grafted with ethylene diamine tetraacetic acid modified electrode.

  6. Radiation protection by ascorbic acid in sodium alginate solutions

    International Nuclear Information System (INIS)

    Aliste, A.J.; Mastro, N.L. Del

    2004-01-01

    Alginates are gelling hydrocolloids extracted from brown seaweed used widely in the nourishing and pharmaceutical industries. As alginic acid gellification retard food entrance in the stomach alginate is an additive used in diets. The objective of this work was to study the protective action of the ascorbic acid in alginate solutions against the action of 60 Co gamma radiation. One % (w/v) solutions of alginate had been used and concentrations of ascorbic acid varied from 0 to 2.5% (w/v). The solutions were irradiated with doses up to 10 kGy. Viscosity/dose relationship and the p H of the solutions at 25 Centigrade were determined. Ascorbic acid behaved as an antioxidant against radiation oxidative shock in this model system of an irradiated viscous solution. Besides its radiation protective role on alginate solutions ascorbic acid promoted a viscosity increase in the range of concentrations employed. (Author)

  7. Inhibitory effects of ascorbic acid, vitamin E, and vitamin B-complex on the biological activities induced by Bothrops venom.

    Science.gov (United States)

    Oliveira, Carlos Henrique de Moura; Assaid Simão, Anderson; Marcussi, Silvana

    2016-01-01

    Natural compounds have been widely studied with the aim of complementing antiophidic serum therapy. The present study evaluated the inhibitory potential of ascorbic acid and a vitamin complex, composed of ascorbic acid, vitamin E, and all the B-complex vitamins, on the biological activities induced by snake venoms. The effect of vitamins was evaluated on the phospholipase, proteolytic, coagulant, and fibrinogenolytic activities induced by Bothrops moojeni (Viperidae), B. jararacussu, and B. alternatus snake venoms, and the hemagglutinating activity induced by B. jararacussu venom. The vitamin complex (1:5 and 1:10 ratios) totally inhibited the fibrinogenolytic activity and partially the phospholipase activity and proteolytic activity on azocasein induced by the evaluated venoms. Significant inhibition was observed in the coagulation of human plasma induced by venoms from B. alternatus (1:2.5 and 1:5, to vitamin complex and ascorbic acid) and B. moojeni (1:2.5 and 1:5, to vitamin complex and ascorbic acid). Ascorbic acid inhibited 100% of the proteolytic activities of B. moojeni and B. alternatus on azocasein, at 1:10 ratio, the effects of all the venoms on fibrinogen, the hemagglutinating activity of B. jararacussu venom, and also extended the plasma coagulation time induced by all venoms analyzed. The vitamins analyzed showed relevant in vitro inhibitory potential over the activities induced by Bothrops venoms, suggesting their interaction with toxins belonging to the phospholipase A2, protease, and lectin classes. The results can aid further research in clarifying the possible mechanisms of interaction between vitamins and snake enzymes.

  8. Sodium orthovanadate associated with pharmacological doses of ascorbate causes an increased generation of ROS in tumor cells that inhibits proliferation and triggers apoptosis

    Energy Technology Data Exchange (ETDEWEB)

    Günther, T-hat nia Mara Fischer; Kviecinski, Maicon Roberto; Baron, Carla Cristine; Felipe, Karina Bettega; Farias, Mirelle Sifroni; Ourique da Silva, Fabiana; Bücker, Nádia Cristina Falcão [Departamento de Bioquímica, Universidade Federal de Santa Catarina, Florianópolis (Brazil); Pich, Claus Tröger [Campus de Araranguá, Universidade Federal de Santa Catarina, Araranguá (Brazil); Ferreira, Eduardo Antonio [Universidade de Brasília, Faculdade de Ceilândia, DF (Brazil); Filho, Danilo Wilhelm [Departamento de Ecologia e Zoologia, Universidade Federal de Santa Catarina, Florianópolis (Brazil); Verrax, Julien; Calderon, Pedro Buc [Toxicology and Cancer Biology Research Group, Louvain Drug Research Institute, Université Catholique de Louvain, Brussels (Belgium); Pedrosa, Rozangela Curi, E-mail: rozangelapedrosa@gmail.com [Departamento de Bioquímica, Universidade Federal de Santa Catarina, Florianópolis (Brazil)

    2013-01-18

    Graphical abstract: -- Abstract: Pharmacological doses of ascorbate were evaluated for its ability to potentiate the toxicity of sodium orthovanadate (Na{sub 3}VO{sub 4}) in tumor cells. Cytotoxicity, inhibition of cell proliferation, generation of ROS and DNA fragmentation were assessed in T24 cells. Na{sub 3}VO{sub 4} was cytotoxic against T24 cells (EC{sub 50} = 5.8 μM at 24 h), but in the presence of ascorbate (100 μM) the EC{sub 50} fell to 3.3 μM. Na{sub 3}VO{sub 4} plus ascorbate caused a strong inhibition of cell proliferation (up to 20%) and increased the generation of ROS (4-fold). Na{sub 3}VO{sub 4} did not directly cleave plasmid DNA, at this aspect no synergism was found occurring between Na{sub 3}VO{sub 4} and ascorbate once the resulting action of the combination was no greater than that of both substances administered separately. Cells from Ehrlich ascites carcinoma-bearing mice were used to determine the activity of antioxidant enzymes, the extent of the oxidative damage and the type of cell death. Na{sub 3}VO{sub 4} alone, or combined with ascorbate, increased catalase activity, but only Na{sub 3}VO{sub 4} plus ascorbate increased superoxide dismutase activity (up to 4-fold). Oxidative damage on proteins and lipids was higher due to the treatment done with Na{sub 3}VO{sub 4} plus ascorbate (2–3-fold). Ascorbate potentiated apoptosis in tumor cells from mice treated with Na{sub 3}VO{sub 4}. The results indicate that pharmacological doses of ascorbate enhance the generation of ROS induced by Na{sub 3}VO{sub 4} in tumor cells causing inhibition of proliferation and apoptosis. Apoptosis induced by orthovanadate and ascorbate is closer related to inhibition on Bcl-xL and activation of Bax. Our data apparently rule out a mechanism of cell demise p53-dependent or related to Cdk2 impairment.

  9. Macrokinetics of magnesium sulfite oxidation inhibited by ascorbic acid

    International Nuclear Information System (INIS)

    Lidong, Wang; Yongliang, Ma; Wendi, Zhang; Qiangwei, Li; Yi, Zhao; Zhanchao, Zhang

    2013-01-01

    Graphical abstract: Ascorbic acid is used as an inhibitor to retard the oxidation rate of magnesium sulfite. It shows that the oxidation rate would decrease greatly with the rise of initial ascorbic acid concentration, which provides a useful reference for sulfite recovery in magnesia desulfurization. -- Highlights: • We studied the kinetics of magnesium sulfite oxidation inhibited by ascorbic acid. • The oxidation process was simulated by a three-phase model and proved by HPLC–MS. • We calculated the kinetic parameters of intrinsic oxidation of magnesium sulfite. -- Abstract: Magnesia flue gas desulfurization is a promising process for small to medium scale industrial coal-fired boilers in order to reduce sulfur dioxide emissions, in which oxidation control of magnesium sulfite is of great importance for the recycling of products. Effects of four inhibitors were compared by kinetic experiments indicating that ascorbic acid is the best additive, which retards the oxidation process of magnesium sulfite in trace presence. The macrokinetics of magnesium sulfite oxidation inhibited by ascorbic acid were studied. Effects of the factors, including ascorbic acid concentration, magnesium sulfite concentration, oxygen partial pressure, pH, and temperature, were investigated in a stirred reactor with bubbling. The results show that the reaction rate is −0.55 order in ascorbic acid, 0.77 in oxygen partial pressure, and zero in magnesium sulfite concentration, respectively. The apparent activation energy is 88.0 kJ mol −1 . Integrated with the kinetic model, it is concluded that the oxidation rate of magnesium sulfite inhibited by ascorbic acid is controlled by the intrinsic chemical reaction. The result provides a useful reference for sulfite recovery in magnesia desulfurization

  10. Nitric Oxide in Plants: The Roles of Ascorbate and Hemoglobin

    Science.gov (United States)

    Wang, Xiaoguang; Hargrove, Mark S.

    2013-01-01

    Ascorbic acid and hemoglobins have been linked to nitric oxide metabolism in plants. It has been hypothesized that ascorbic acid directly reduces plant hemoglobin in support of NO scavenging, producing nitrate and monodehydroascorbate. In this scenario, monodehydroascorbate reductase uses NADH to reduce monodehydroascorbate back to ascorbate to sustain the cycle. To test this hypothesis, rates of rice nonsymbiotic hemoglobin reduction by ascorbate were measured directly, in the presence and absence of purified rice monodehydroascorbate reductase and NADH. Solution NO scavenging was also measured methodically in the presence and absence of rice nonsymbiotic hemoglobin and monodehydroascorbate reductase, under hypoxic and normoxic conditions, in an effort to gauge the likelihood of these proteins affecting NO metabolism in plant tissues. Our results indicate that ascorbic acid slowly reduces rice nonsymbiotic hemoglobin at a rate identical to myoglobin reduction. The product of the reaction is monodehydroascorbate, which can be efficiently reduced back to ascorbate in the presence of monodehydroascorbate reductase and NADH. However, our NO scavenging results suggest that the direct reduction of plant hemoglobin by ascorbic acid is unlikely to serve as a significant factor in NO metabolism, even in the presence of monodehydroascorbate reductase. Finally, the possibility that the direct reaction of nitrite/nitrous acid and ascorbic acid produces NO was measured at various pH values mimicking hypoxic plant cells. Our results suggest that this reaction is a likely source of NO as the plant cell pH drops below 7, and as nitrite concentrations rise to mM levels during hypoxia. PMID:24376554

  11. Studies on the biological oxidation - The oxidation of ascorbic acid (vitamin C) in biological fluids

    OpenAIRE

    Guzmán Barrón, E. S.; Guzmán Barrón, Alberto; Klemperer, Friedrich

    2014-01-01

    Biological fluids can be divided according to their behavior toward ascorbic acid into two groups: those having an inhibitory mechanism that protects the ascorbic acid oxidation, and those lacking this mechanism. Animal fluids and some of vegetable origin (those containing dosables amounts of ascorbic acid) corresponding to the first group. Ascorbic acid is protected from oxidation in the fluids by the action of copper catalyst. Fluids from plants (those that contain very little ascorbic acid...

  12. Modeling the degradation kinetics of ascorbic acid.

    Science.gov (United States)

    Peleg, Micha; Normand, Mark D; Dixon, William R; Goulette, Timothy R

    2018-06-13

    Most published reports on ascorbic acid (AA) degradation during food storage and heat preservation suggest that it follows first-order kinetics. Deviations from this pattern include Weibullian decay, and exponential drop approaching finite nonzero retention. Almost invariably, the degradation rate constant's temperature-dependence followed the Arrhenius equation, and hence the simpler exponential model too. A formula and freely downloadable interactive Wolfram Demonstration to convert the Arrhenius model's energy of activation, E a , to the exponential model's c parameter, or vice versa, are provided. The AA's isothermal and non-isothermal degradation can be simulated with freely downloadable interactive Wolfram Demonstrations in which the model's parameters can be entered and modified by moving sliders on the screen. Where the degradation is known a priori to follow first or other fixed order kinetics, one can use the endpoints method, and in principle the successive points method too, to estimate the reaction's kinetic parameters from considerably fewer AA concentration determinations than in the traditional manner. Freeware to do the calculations by either method has been recently made available on the Internet. Once obtained in this way, the kinetic parameters can be used to reconstruct the entire degradation curves and predict those at different temperature profiles, isothermal or dynamic. Comparison of the predicted concentration ratios with experimental ones offers a way to validate or refute the kinetic model and the assumptions on which it is based.

  13. Ascorbic acid: Nonradioactive extracellular space marker in canine heart

    International Nuclear Information System (INIS)

    Reil, G.H.; Frombach, R.; Kownatzki, R.; Quante, W.; Lichtlen, P.R.

    1987-01-01

    The distribution pattern of ascorbic acid and L-[ 14 C]ascorbic acid in myocardial tissue was compared with those of the classical radioactive extracellular space markers [ 3 H]-inulin, [ 3 H]sucrose, and Na 82 Br. A new polarographic techniques was developed for analogue registration of ascorbic acid concentration in coronary venous blood. The kinetic data of the markers were studied in an open-chest canine heart preparation during a constant tracer infusion of up to 9 min. Distribution volumes were calculated based on the mean transit time method of Zierler. The distribution volume of ascorbic acid as well as of L-[ 14 C]ascorbic acid in myocardial tissue agreed closely with those of [ 3 H]inulin and [ 3 H]sucrose as well as 82 Br. The obtained kinetic data confirmed that ascorbic acid exhibits the physicochemical properties of an extracellular space marker, though this compound was shown to leak slowly into myocardial cells. Favorable attributes of this indicator are its low molecular weight, high diffusibility in interstitial fluid, low binding affinity to macromolecules, and high transcapillary as well as low transplasmalemmal penetration rate. Therefore, this nonradioactive marker can be applied in a safe and simple fashion, and without untoward side effects in experimental animals as well as in patients

  14. Ascorbate regulates haematopoietic stem cell function and leukaemogenesis.

    Science.gov (United States)

    Agathocleous, Michalis; Meacham, Corbin E; Burgess, Rebecca J; Piskounova, Elena; Zhao, Zhiyu; Crane, Genevieve M; Cowin, Brianna L; Bruner, Emily; Murphy, Malea M; Chen, Weina; Spangrude, Gerald J; Hu, Zeping; DeBerardinis, Ralph J; Morrison, Sean J

    2017-09-28

    Stem-cell fate can be influenced by metabolite levels in culture, but it is not known whether physiological variations in metabolite levels in normal tissues regulate stem-cell function in vivo. Here we describe a metabolomics method for the analysis of rare cell populations isolated directly from tissues and use it to compare mouse haematopoietic stem cells (HSCs) to restricted haematopoietic progenitors. Each haematopoietic cell type had a distinct metabolic signature. Human and mouse HSCs had unusually high levels of ascorbate, which decreased with differentiation. Systemic ascorbate depletion in mice increased HSC frequency and function, in part by reducing the function of Tet2, a dioxygenase tumour suppressor. Ascorbate depletion cooperated with Flt3 internal tandem duplication (Flt3 ITD ) leukaemic mutations to accelerate leukaemogenesis, through cell-autonomous and possibly non-cell-autonomous mechanisms, in a manner that was reversed by dietary ascorbate. Ascorbate acted cell-autonomously to negatively regulate HSC function and myelopoiesis through Tet2-dependent and Tet2-independent mechanisms. Ascorbate therefore accumulates within HSCs to promote Tet activity in vivo, limiting HSC frequency and suppressing leukaemogenesis.

  15. Ascorbic acid transport and accumulation in human neutrophils

    International Nuclear Information System (INIS)

    Washko, P.; Rotrosen, D.; Levine, M.

    1989-01-01

    The transport, accumulation, and distribution of ascorbic acid were investigated in isolated human neutrophils utilizing a new ascorbic acid assay, which combined the techniques of high performance liquid chromatography and coulometric electrochemical detection. Freshly isolated human neutrophils contained 1.0-1.4 mM ascorbic acid, which was localized greater than or equal to 94% to the cytosol, was not protein bound, and was present only as ascorbic acid and not as dehydroascorbic acid. Upon addition of ascorbic acid to the extracellular medium in physiologic amounts, ascorbic acid was accumulated in neutrophils in millimolar concentrations. Accumulation was mediated by a high affinity and a low affinity transporter; both transporters were responsible for maintenance of concentration gradients as large as 50-fold. The high affinity transporter had an apparent Km of 2-5 microns by Lineweaver-Burk and Eadie-Hofstee analyses, and the low affinity transporter had an apparent Km of 6-7 mM by similar analyses. Each transporter was saturable and temperature dependent. In normal human blood the high affinity transporter should be saturated, whereas the low affinity transporter should be in its linear phase of uptake

  16. Ascorbic acid deficiency in patients with lichen planus.

    Science.gov (United States)

    Nicolae, Ilinca; Mitran, Cristina Iulia; Mitran, Madalina Irina; Ene, Corina Daniela; Tampa, Mircea; Georgescu, Simona Roxana

    2017-01-01

    Recent studies have highlighted the role of oxidative stress in the pathogenesis of lichen planus (LP). In the present study, the interest of the authors is focused on the investigation of ascorbic acid status in patients with LP and identification of parameters that might influence the level of this vitamin. We analyzed the level of urinary ascorbic acid (reflectometric method) in 77 patients with LP (cutaneous LP (CLP)-49 cases; oral LP (OLP)-28 cases) and 50 control subjects. The evaluation of all participants included clinical examination and laboratory and imaging tests. Compared to the control group (19.82 mg/dl) the level of ascorbic acid was significantly lower both in patients with CLP (8.47 mg/dl, p = 0.001) and in those with OLP (8.04 mg/dl, p = 0.001). In patients with LP it was found that the deficiency of ascorbic acid increases with age (r = -0.318, p = 0.032). The urinary concentrations of ascorbic acid were significantly lower in patients with LP associated with infections compared to patients with LP without infections. The urinary ascorbic acid level may be a useful parameter in identifying patients with LP who are at risk of developing viral or bacterial infections.

  17. Antagonism of ascorbate against the radioprotective action of cysteamine

    Energy Technology Data Exchange (ETDEWEB)

    Naeslund, M; Ehrenberg, L; Djalali-Behzad, G [Stockholm Univ. (Sweden). Radiobiologiska Institutionen

    1976-07-01

    An investigation has been carried out into the interaction of cysteamine (MEA) and ascorbate on the radiosensitivity of E.coli, with painstaking removal of autoxidation products from glassware. Trace amounts of copper could be effectively removed, and the influence of small amounts of iron contaminating the analytical grade phosphate was assessed. The bacteria were exposed to MEA and/or ascorbate for 1 hour at 37/sup 0/C, irradiation with 42 or 58 krad of /sup 60/Co ..gamma..rays taking place 30 to 40 minutes after the additions. Survival studies demonstrated the reversion of a major fraction of the radioprotective action of MEA (2 or 6 mM) by ascorbate (5 mM) simultaneously present in the medium. Net RNA synthesis, determined by the incorporation of /sup 3/H-uridine, was suppressed by MEA and this was partly reversed by ascorbate. The irradiation of bacterium suspensions containing MEA and ascorbate was found to provoke a conspicuous stimulation of RNA synthesis above the level of unirradiated parallel samples. The effects of some oxidizing treatments (dehydroascorbic acid, hydrogen peroxide, 3.6 ..mu..M FeSO/sub 4/ or 1 ..mu..M CuSO/sub 4/) together with MEA were also studied. Possible mechanisms for the ability of ascorbate to counteract the radioprotective action of MEA are discussed, and the implication of monodehydroascorbate formed during irradiation is suggested.

  18. Guinea pig ascorbate status predicts tetrahydrobiopterin plasma concentration and oxidation ratio in vivo.

    Science.gov (United States)

    Mortensen, Alan; Hasselholt, Stine; Tveden-Nyborg, Pernille; Lykkesfeldt, Jens

    2013-10-01

    Tetrahydrobiopterin (BH₄) is an essential co-factor of nitric oxide synthases and is easily oxidized to dihydrobiopterin (BH₂) which promotes endothelial nitric oxide synthase uncoupling and deleterious superoxide production. Vitamin C has been shown to improve endothelial function by different mechanisms, some involving BH₄. The hypothesis of the present study was that vitamin C status, in particular low levels, influences biopterin redox status in vivo. Like humans, the guinea pig lacks the ability to synthesize vitamin C and was therefore used as model. Seven day old animals (n = 10/group) were given a diet containing 100, 250, 500, 750, 1000, or 1500 ppm vitamin C until euthanasia at age 60-64 days. Blood samples were drawn from the heart and analyzed for ascorbate, dehydroascorbic acid (DHA), BH₄ and BH₂ by high-performance liquid chromatography. Plasma BH₄ levels were found to be significantly lower in animals fed 100 ppm vitamin C compared to all other groups (P < .05 or less). BH₂ levels were not significantly different between groups but the BH₂-to-BH₄ ratio was higher in the group fed 100 ppm vitamin C (P < .001 all cases). Significant positive correlations between BH4 and ascorbate and between BH₂-to-BH₄ ratio and DHA were observed (P < .0001 both cases). Likewise, BH₂-to-BH₄ ratio was negatively correlated with ascorbate (P < .0001) as was BH₄ and DHA (P < .005). In conclusion, the redox status of plasma biopterins, essentially involved in vasodilation, depends on the vitamin C status in vivo. Thus, ingestion of insufficient quantities of vitamin C not only leads to vitamin C deficiency but also to increased BH₄ oxidation which may promote endothelial dysfunction. © 2013 Elsevier Inc. All rights reserved.

  19. Enzyme Informatics

    Science.gov (United States)

    Alderson, Rosanna G.; Ferrari, Luna De; Mavridis, Lazaros; McDonagh, James L.; Mitchell, John B. O.; Nath, Neetika

    2012-01-01

    Over the last 50 years, sequencing, structural biology and bioinformatics have completely revolutionised biomolecular science, with millions of sequences and tens of thousands of three dimensional structures becoming available. The bioinformatics of enzymes is well served by, mostly free, online databases. BRENDA describes the chemistry, substrate specificity, kinetics, preparation and biological sources of enzymes, while KEGG is valuable for understanding enzymes and metabolic pathways. EzCatDB, SFLD and MACiE are key repositories for data on the chemical mechanisms by which enzymes operate. At the current rate of genome sequencing and manual annotation, human curation will never finish the functional annotation of the ever-expanding list of known enzymes. Hence there is an increasing need for automated annotation, though it is not yet widespread for enzyme data. In contrast, functional ontologies such as the Gene Ontology already profit from automation. Despite our growing understanding of enzyme structure and dynamics, we are only beginning to be able to design novel enzymes. One can now begin to trace the functional evolution of enzymes using phylogenetics. The ability of enzymes to perform secondary functions, albeit relatively inefficiently, gives clues as to how enzyme function evolves. Substrate promiscuity in enzymes is one example of imperfect specificity in protein-ligand interactions. Similarly, most drugs bind to more than one protein target. This may sometimes result in helpful polypharmacology as a drug modulates plural targets, but also often leads to adverse side-effects. Many cheminformatics approaches can be used to model the interactions between druglike molecules and proteins in silico. We can even use quantum chemical techniques like DFT and QM/MM to compute the structural and energetic course of enzyme catalysed chemical reaction mechanisms, including a full description of bond making and breaking. PMID:23116471

  20. PULSE SYNTHESIZING GENERATOR

    Science.gov (United States)

    Kerns, Q.A.

    1963-08-01

    >An electronlc circuit for synthesizing electrical current pulses having very fast rise times includes several sinewave generators tuned to progressively higher harmonic frequencies with signal amplitudes and phases selectable according to the Fourier series of the waveform that is to be synthesized. Phase control is provided by periodically triggering the generators at precisely controlled times. The outputs of the generators are combined in a coaxial transmission line. Any frequency-dependent delays that occur in the transmission line can be readily compensated for so that the desired signal wave shape is obtained at the output of the line. (AEC)

  1. One-step synthesis of delta-MnO2 nanoparticles using ascorbic acid and their scavenging properties to Pb(II), Zn(II) and methylene blue

    NARCIS (Netherlands)

    Wang, M.X.; Pang, P.; Koopal, L.K.; Qiu, G.H.; Wang, Y.; Liu, F.

    2014-01-01

    To obtain delta-MnO2 particles with a large specific surface area, MnO2 was synthesized in an ice-water bath using ascorbic acid (AA) to reduce KMnO4. At pH 3 and 5 and KMnO4/AA molar ratios of 8/1 and 10/1, nanoparticles of delta-MnO2 were produced. The specific surface areas (SSAs) of the samples

  2. Low brain ascorbic acid increases susceptibility to seizures in mouse models of decreased brain ascorbic acid transport and Alzheimer's disease.

    Science.gov (United States)

    Warner, Timothy A; Kang, Jing-Qiong; Kennard, John A; Harrison, Fiona E

    2015-02-01

    Seizures are a known co-occurring symptom of Alzheimer's disease, and they can accelerate cognitive and neuropathological dysfunction. Sub-optimal vitamin C (ascorbic acid) deficiency, that is low levels that do not lead the sufferer to present with clinical signs of scurvy (e.g. lethargy, hemorrhage, hyperkeratosis), are easily obtainable with insufficient dietary intake, and may contribute to the oxidative stress environment of both Alzheimer's disease and epilepsy. The purpose of this study was to test whether mice that have diminished brain ascorbic acid in addition to carrying human Alzheimer's disease mutations in the amyloid precursor protein (APP) and presenilin 1 (PSEN1) genes, had altered electrical activity in the brain (electroencephalography; EEG), and were more susceptible to pharmacologically induced seizures. Brain ascorbic acid was decreased in APP/PSEN1 mice by crossing them with sodium vitamin C transporter 2 (SVCT2) heterozygous knockout mice. These mice have an approximately 30% decrease in brain ascorbic acid due to lower levels of SVCT2 that supplies the brain with ASC. SVCT2+/-APP/PSEN1 mice had decreased ascorbic acid and increased oxidative stress in brain, increased mortality, faster seizure onset latency following treatment with kainic acid (10 mg/kg i.p.), and more ictal events following pentylenetetrazol (50 mg/kg i.p.) treatment. Furthermore, we report the entirely novel phenomenon that ascorbic acid deficiency alone increased the severity of kainic acid- and pentylenetetrazol-induced seizures. These data suggest that avoiding ascorbic acid deficiency may be particularly important in populations at increased risk for epilepsy and seizures, such as Alzheimer's disease. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. A Flexible Ascorbic Acid Fuel Cell with a Microchannel Fabricated using MEMS Techniques

    Science.gov (United States)

    Mogi, Hiroshi; Fukushi, Yudai; Koide, Syohei; Sano, Ryohei; Sasaki, Tsubasa; Nishioka, Yasushiro

    2013-12-01

    We fabricated a miniature ascorbic acid fuel cells equipped with a microchannel for the circulation of ascorbic acid (AA) solution using micro electronic mechanical system techniques. The fuel cell was fabricated on a flexible polyimide substrate, and its porous carbon-coated aluminium (Al) electrodes of 2.8 mm in width and 11 mm in length were formed using photolithography and screen-printing techniques. The porous carbon was deposited by screen-printing of carbon-black ink on the Al electrode surfaces in order to increase the effective electrode surface area and to absorb more enzymes on the cathode surface. The microchannel with a depth of 200 μm was fabricated using a hot-embossing technique. A maximum power of 0.60 μW at 0.58 V that corresponds to a power density of 1.83 μW/cm2 was realized by introducing a 200 mM concentrated AA solution at room temperature.

  4. Relationship of ascorbic acid metabolism with the cytoplasmic male sterility in pepper (Capsicum annuum L.)

    International Nuclear Information System (INIS)

    Wen, J.; Deng, M.

    2015-01-01

    To elucidate the metabolic mechanism of Ascorbic Acid (ASA) in the CMS-pepper anthers, the metabolism changes in the reactive oxygen species (ROS) contents, antioxidants contents and ROS scavenging enzymatic activities were investigated in the anther mitochondria of CMS-9704A and maintainer-9704B. At the abortion stage, anthers of CMS-9704A had higher contents of ROS than those of the maintainer. Simultaneously, there were lower contents of ASA and glutathione (GSH) in stage 2 and 3, and the lower activities of ascorbate peroxidase (APX) and glutathione perodixase (GPX) in stage 3 in scavenging ROS in the anthers of the CMS line than maintainer. The expression level of APX and GPX in stage 3 in anthers of CMS-9704A was obviously inhibited when ROS produced with a great deal during anther stage; however the gene expression kept normal in the maintainer. Excessive accumulation of ROS, significant reduction activities and gene expression level of ROS-scavenging enzyme were coinstantaneous with CMS. (author)

  5. Oral metformin-ascorbic acid co-administration ameliorates alcohol-induced hepatotoxicity in rats.

    Science.gov (United States)

    Adeneye, A A; Benebo, A S

    2007-01-01

    Alcoholic liver disease remains a major cause of liver failure worldwide with no available curative or prophylactic therapy as at present. High dose metformin is reported to ameliorate liver injuries in both human and animal models of acute and chronic alcoholic liver injuries. The aim of the present in vivo animal study was to determine whether metformin-ascorbic acid co-administration also prevents alcoholic hepatotoxicity in chronic alcohol exposure. In the present study, ameliorating effect of 200 mg/ kg/day of ascorbic acid (Asc), 500 mg/kg/day of metformin (Met) and their co-administration (Met-Asc) were investigated in 5 groups of 50% ethanol-treated male Wistar rats for 2 weeks of the experiment. The body weight of each rat was taken on days 1, 7, and 14 of the experiment, respectively. On day 15, fasted blood samples for plasma lipids and liver enzyme markers were collected via cardiac puncture from the rats under diethyl ether anaesthesia. Results showed that administration of graded oral doses of 50% ethanol for 14 days significantly (pcholesterol (PTC), high density lipoprotein (HDL-c), and low density lipoprotein (LDL-c). However, these elevations were significantly (pascorbic acid co-administration protected the liver against the deleterious effects of chronic high dose alcohol and the hepatoprotective effect of Met-Asc appeared to be due mainly to the metformin molecule of the drug combination. However, further studies would be required to evaluate the mechanisms underlying the observed effects.

  6. Green reduction of graphene oxide by ascorbic acid

    Science.gov (United States)

    Khosroshahi, Zahra; Kharaziha, Mahshid; Karimzadeh, Fathallah; Allafchian, Alireza

    2018-01-01

    Graphene, a single layer of sp2-hybridized carbon atoms in a hexagonal (two-dimensional honey-comb) lattice, has attracted strong scientific and technological interest due to its novel and excellent optical, chemical, electrical, mechanical and thermal properties. The solution-processable chemical reduction of Graphene oxide (GO is considered as the most favorable method regarding mass production of graphene. Generally, the reduction of GO is carried out by chemical approaches using different reductants such as hydrazine and sodium borohydride. These components are corrosive, combustible and highly toxic which may be dangerous for personnel health and the environment. Hence, these reducing agents are not promising choice for reducing of graphene oxide (GO). As a consequence, it is necessary for further development and optimization of eco-friendly, natural reducing agent for clean and effective reduction of GO. Ascorbic acid, an eco-friendly and natural reducing agents, having a mild reductive ability and nontoxic property. So, the aim of this research was to green synthesis of GO with ascorbic acid. For this purpose, the required amount of NaOH and ascorbic acid were added to GO solution (0.5 mg/ml) and were heated at 95 °C for 1 hour. According to the X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and electrochemical results, GO were reduced with ascorbic acid like hydrazine with better electrochemical properties and ascorbic acid is an ideal substitute for hydrazine in the reduction of graphene oxide process.

  7. Ascorbic Acid Contents in Chili Peppers (Capsicum L.

    Directory of Open Access Journals (Sweden)

    Owk ANIEL KUMAR

    2009-12-01

    Full Text Available The genus Capsicum commonly known as chili pepper is a major spice crop and is almost cosmopolitan in distribution. The nutritive value of chili pepper is largely determined by ascorbic acid content. The fruits at five ripening stages viz., (M1, M2, M3, M4 and M5 from seventeen cultivars of Capsicum annuum L and one cultivar of Capsicum frutescens L were analyzed for ascorbic acid content. Among eighteen genotypes the C. annuum var. IC: 119262(CA2 showed higher ascorbic acid content (mg/100g FW i.e., 208.00.68 (M1, 231.00.66 (M2, 280.00.31 (M3, 253.00.34 (M4 and 173.70.27 (M5. The study revealed that the gradual increase in ascorbic acid content from green to red and subsequently declined in the lateral stages (red partially dried and red fully dried fruits. The variability of ascorbic acid content in the genotypes suggests that these selected genotypes may be use full as parents in hybridization programs to produce fruits with good nutritional values.

  8. Effect of ascorbic acid on prevention of hypercholesterolemia induced atherosclerosis.

    Science.gov (United States)

    Das, S; Ray, R; Snehlata; Das, N; Srivastava, L M

    2006-04-01

    The notion that oxidation of lipids and propagation of free radicals may contribute to the pathogenesis of atherosclerosis is supported by a large body of evidence. To circumvent the damage caused by oxygen free radicals, antioxidants are needed which provide the much needed neutralization of free radical by allowing the pairing of electrons. In this study we have investigated the effect of ascorbic acid, a water soluble antioxidant on the development of hypercholesterolemia induced atherosclerosis in rabbits. Rabbits were made hypercholesterolemic and atherosclerotic by feeding 100 mg cholesterol/day. Different doses of ascorbic acid were administered to these rabbits. Low dose of ascorbic acid (0.5 mg/100 g body weight/day) did not have any significant effect on the percent of total area covered by atherosclerotic plaque. However, ascorbic acid when fed at a higher dose (15 mg/100 g body weight/day) was highly effective in reducing the atherogenecity. With this dose the percent of total surface area covered by atherosclerotic plaque was significantly less (p ascorbic acid may have great promise in the prevention of hypercholesterolemia induced atherosclerosis.

  9. Two step continuous method to synthesize colloidal spheroid gold nanorods.

    Science.gov (United States)

    Chandra, S; Doran, J; McCormack, S J

    2015-12-01

    This research investigated a two-step continuous process to synthesize colloidal suspension of spheroid gold nanorods. In the first step; gold precursor was reduced to seed-like particles in the presence of polyvinylpyrrolidone and ascorbic acid. In continuous second step; silver nitrate and alkaline sodium hydroxide produced various shape and size Au nanoparticles. The shape was manipulated through weight ratio of ascorbic acid to silver nitrate by varying silver nitrate concentration. The specific weight ratio of 1.35-1.75 grew spheroid gold nanorods of aspect ratio ∼1.85 to ∼2.2. Lower weight ratio of 0.5-1.1 formed spherical nanoparticle. The alkaline medium increased the yield of gold nanorods and reduced reaction time at room temperature. The synthesized gold nanorods retained their shape and size in ethanol. The surface plasmon resonance was red shifted by ∼5 nm due to higher refractive index of ethanol than water. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Affinity resins as new tools for identifying target proteins of ascorbic acid.

    Science.gov (United States)

    Iwaoka, Yuji; Nishino, Kohei; Ishikawa, Takahiro; Ito, Hideyuki; Sawa, Yoshihiro; Tai, Akihiro

    2018-02-12

    l-Ascorbic acid (AA) has diverse physiological functions, but little is known about the functional mechanisms of AA. In this study, we synthesized two types of affinity resin on which AA is immobilized in a stable form to identify new AA-targeted proteins, which can provide important clues for elucidating unknown functional mechanisms of AA. To our knowledge, an affinity resin on which AA as a ligand is immobilized has not been prepared, because AA is very unstable and rapidly degraded in an aqueous solution. By using the affinity resins, cytochrome c (cyt c) was identified as an AA-targeted protein, and we showed that oxidized cyt c exhibits specific affinity for AA. These results suggest that two kinds of AA-affinity resin can be powerful tools to identify new target proteins of AA.

  11. Ascorbic acid prevents cellular uptake and improves biocompatibility of chitosan nanoparticles.

    Science.gov (United States)

    Elshoky, Hisham A; Salaheldin, Taher A; Ali, Maha A; Gaber, Mohamed H

    2018-04-11

    Chitosan nanoparticles have many applications, such as gene and drug delivery, due to their biocompatibility. Chitosan nanoparticles are currently produced by dissolution in acetic acid that affects the biocompatibility at acidic pH. Here, we synthesized and characterized chitosan (CS) and ascorbate chitosan (AsCS) nanoparticles and investigated their cytotoxic effects, internalization, and distribution in the human colon carcinoma cell line using confocal laser scanning microscopy (CLSM). The CS and AsCS nanoparticles were spherical with average particle sizes of 44±8.4nm and 87±13.6nm, respectively. CS nanoparticles were taken up by the cells and showed dose-dependent cytotoxicity. By contrast, AsCS nanoparticles were not internalized and showed no cytotoxicity. Therefore, AsCS nanoparticles are more biocompatible than CS nanoparticles and may be more suitable for extracellular drug delivery. Copyright © 2018 Elsevier B.V. All rights reserved.

  12. Glucansucrases of lactobacilli : characterization of genes, enzymes, and products synthesized

    NARCIS (Netherlands)

    Kralj, Slavko

    2004-01-01

    Lactic acid bacteria (LAB) are widely used in the feed and food (fermentation) industry (e.g. beer, cheese, yoghurt, olives, pickles, sauerkraut and silage). LAB form various metabolites during fermentation of carbohydrates, which contribute positively to the taste, smell and preservation of the

  13. Mitochondria, Energy and Cancer: The Relationship with Ascorbic Acid

    Science.gov (United States)

    González, Michael J.; Rosario-Pérez, Glorivee; Guzmán, Angélica M.; Miranda-Massari, Jorge R.; Duconge, Jorge; Lavergne, Julio; Fernandez, Nadia; Ortiz, Norma; Quintero, Ana; Mikirova, Nina; Riordan, Neil H.; Ricart, Carlos M.

    2012-01-01

    Ascorbic Acid (AA) has been used in the prevention and treatment of cancer with reported effectiveness. Mitochondria may be one of the principal targets of ascorbate's cellular activity and it may play an important role in the development and progression of cancer. Mitochondria, besides generating adenosine triphosphate (ATP), has a role in apoptosis regulation and in the production of regulatory oxidative species that may be relevant in gene expression. At higher concentrations AA may increase ATP production by increasing mitochondrial electron flux, also may induce apoptotic cell death in tumor cell lines, probably via its pro-oxidant action In contrast, at lower concentrations AA displays antioxidant properties that may prevent the activation of oxidant-induced apoptosis. These concentration dependent activities of ascorbate may explain in part the seemingly contradictory results that have been reported previously. PMID:23565030

  14. Ascorbate and dehydroascorbic acid as reliable biomarkers of oxidative stress

    DEFF Research Database (Denmark)

    Lykkesfeldt, Jens

    2007-01-01

    , the analytical reproducibility was tested by repeated analysis of plasma aliquots from one individual over four years. The plasma was subjected to acidic deproteinization with an equal volume of 10% meta-phosphoric acid containing 2 mM EDTA and analyzed for ascorbate and dehydroascorbic acid by high-performance...... liquid chromatography with coulometric detection. In a parallel experiment, stability of human plasma samples treated as above and stored at -80°C for five years was tested in a cohort of 131 individuals. No degradation or shift in the equilibrium between ascorbate and dehydroascorbic acid was observed......Lack of post-sampling stability of ascorbate and dehydroascorbic acid and failure to block their in vivo equilibrium have lowered their value as biomarkers of oxidative stress and limited the ability to further investigate their possible role in disease prevention. In the present paper...

  15. Souper: A Synthesizing Superoptimizer

    OpenAIRE

    Sasnauskas, Raimondas; Chen, Yang; Collingbourne, Peter; Ketema, Jeroen; Lup, Gratian; Taneja, Jubi; Regehr, John

    2017-01-01

    If we can automatically derive compiler optimizations, we might be able to sidestep some of the substantial engineering challenges involved in creating and maintaining a high-quality compiler. We developed Souper, a synthesizing superoptimizer, to see how far these ideas might be pushed in the context of LLVM. Along the way, we discovered that Souper's intermediate representation was sufficiently similar to the one in Microsoft Visual C++ that we applied Souper to that compiler as well. Shipp...

  16. Regiospecificity determinants of human heme oxygenase: differential NADPH- and ascorbate-dependent heme cleavage by the R183E mutant.

    Science.gov (United States)

    Wang, Jinling; Lad, Latesh; Poulos, Thomas L; Ortiz de Montellano, Paul R

    2005-01-28

    The ability of the human heme oxygenase-1 (hHO-1) R183E mutant to oxidize heme in reactions supported by either NADPH-cytochrome P450 reductase or ascorbic acid has been compared. The NADPH-dependent reaction, like that of wild-type hHO-1, yields exclusively biliverdin IXalpha. In contrast, the R183E mutant with ascorbic acid as the reductant produces biliverdin IXalpha (79 +/- 4%), IXdelta (19 +/- 3%), and a trace of IXbeta. In the presence of superoxide dismutase and catalase, the yield of biliverdin IXdelta is decreased to 8 +/- 1% with a corresponding increase in biliverdin IXalpha. Spectroscopic analysis of the NADPH-dependent reaction shows that the R183E ferric biliverdin complex accumulates, because reduction of the iron, which is required for sequential iron and biliverdin release, is impaired. Reversal of the charge at position 183 makes reduction of the iron more difficult. The crystal structure of the R183E mutant, determined in the ferric and ferrous-NO bound forms, shows that the heme primarily adopts the same orientation as in wild-type hHO-1. The structure of the Fe(II).NO complex suggests that an altered active site hydrogen bonding network supports catalysis in the R183E mutant. Furthermore, Arg-183 contributes to the regiospecificity of the wild-type enzyme, but its contribution is not critical. The results indicate that the ascorbate-dependent reaction is subject to a lower degree of regiochemical control than the NADPH-dependent reaction. Ascorbate may be able to reduce the R183E ferric and ferrous dioxygen complexes in active site conformations that cannot be reduced by NADPH-cytochrome P450 reductase.

  17. Biosynthesis of l-Ascorbic Acid and Conversion of Carbons 1 and 2 of l-Ascorbic Acid to Oxalic Acid Occurs within Individual Calcium Oxalate Crystal Idioblasts1

    Science.gov (United States)

    Kostman, Todd A.; Tarlyn, Nathan M.; Loewus, Frank A.; Franceschi, Vincent R.

    2001-01-01

    l-Ascorbic acid (AsA) and its metabolic precursors give rise to oxalic acid (OxA) found in calcium oxalate crystals in specialized crystal idioblast cells in plants; however, it is not known if AsA and OxA are synthesized within the crystal idioblast cell or transported in from surrounding mesophyll cells. Isolated developing crystal idioblasts from Pistia stratiotes were used to study the pathway of OxA biosynthesis and to determine if idioblasts contain the entire path and are essentially independent in OxA synthesis. Idioblasts were supplied with various 14C-labeled compounds and examined by micro-autoradiography for incorporation of 14C into calcium oxalate crystals. [14C]OxA gave heavy labeling of crystals, indicating the isolated idioblasts are functional in crystal formation. Incubation with [1-14C]AsA also gave heavy labeling of crystals, whereas [6-14C]AsA gave no labeling. Labeled precursors of AsA (l-[1-14C]galactose; d-[1-14C]mannose) also resulted in crystal labeling, as did the ascorbic acid analog, d-[1-14C]erythorbic acid. Intensity of labeling of isolated idioblasts followed the pattern OxA > AsA (erythorbic acid) > l-galactose > d-mannose. Our results demonstrate that P. stratiotes crystal idioblasts synthesize the OxA used for crystal formation, the OxA is derived from the number 1 and 2 carbons of AsA, and the proposed pathway of ascorbic acid synthesis via d-mannose and l-galactose is operational in individual P. stratiotes crystal idioblasts. These results are discussed with respect to fine control of calcium oxalate precipitation and the concept of crystal idioblasts as independent physiological compartments. PMID:11161021

  18. Effect of different nutrient supply and other growth factors on the activity of the oxidizing enzymes in plants

    Energy Technology Data Exchange (ETDEWEB)

    Amberger, A

    1960-01-01

    Among the plants studied were french beans and peas; the oxidizing enzymes examined were ascorbic acid oxidase, cytochrome oxidase, phenol oxidase, peroxidase and catalase. Increasing the K dosage reduced enzyme activity and raised dry matter contents until at a very high dosage this action was reversed. Both N and P increased enzyme activity and yields. With B high enzyme activity and low dry matter content were both associated with deficiency and toxicity levels. Increasing the Fe dosage led to a rise in both dry matter content and enzyme activity, whereas F depressed yields and raised enzyme activity. Lack of water increased respiration. Light inhibited all enzyme activity.

  19. Effects of ascorbic acid on carcinogenicity and acute toxicity of nickel subsulfide, and on tumor transplants growth in gulonolactone oxidase knock-out mice and wild-type C57BL mice

    Energy Technology Data Exchange (ETDEWEB)

    Kasprzak, Kazimierz S. [Laboratory of Comparative Carcinogenesis, National Cancer Institute at Frederick, Frederick, MD 21702 (United States); Diwan, Bhalchandra A. [Basic Research Program, Science Applications International Corporation-Frederick, Inc., National Cancer Institute at Frederick, Frederick, MD 21702 (United States); Kaczmarek, Monika Z. [Laboratory of Comparative Carcinogenesis, National Cancer Institute at Frederick, Frederick, MD 21702 (United States); Logsdon, Daniel L. [Laboratory Animal Sciences Program, Science Applications International Corporation-Frederick, Inc., National Cancer Institute at Frederick, Frederick, MD 21702 (United States); Fivash, Mathew J. [Data Management Services, National Cancer Institute at Frederick, Frederick, MD 21702 (United States); Salnikow, Konstantin, E-mail: salnikok@mail.nih.gov [Laboratory of Comparative Carcinogenesis, National Cancer Institute at Frederick, Frederick, MD 21702 (United States)

    2011-11-15

    The aim of this study was to test a hypothesis that ascorbate depletion could enhance carcinogenicity and acute toxicity of nickel. Homozygous L-gulono- < gamma > -lactone oxidase gene knock-out mice (Gulo-/- mice) unable to produce ascorbate and wild-type C57BL mice (WT mice) were injected intramuscularly with carcinogenic nickel subsulfide (Ni{sub 3}S{sub 2}), and observed for the development of injection site tumors for 57 weeks. Small pieces of one of the induced tumors were transplanted subcutaneously into separate groups of Gulo-/- and WT mice and the growth of these tumors was measured for up to 3 months. The two strains of mice differed significantly with regard to (1) Ni{sub 3}S{sub 2} carcinogenesis: Gulo-/- mice were 40% more susceptible than WT mice; and (2) transplanted tumors development: Gulo-/- mice were more receptive to tumor growth than WT mice, but only in terms of a much shorter tumor latency; later in the exponential phase of growth, the growth rates were the same. And, with adequate ascorbate supplementation, the two strains were equally susceptible to acute toxicity of Ni{sub 3}S{sub 2}. Statistically significant effects of dietary ascorbate dosing levels were the following: (1) reduction in ascorbate supplementation increased acute toxicity of Ni{sub 3}S{sub 2} in Gulo-/- mice; (2) ascorbate supplementation extended the latency of transplanted tumors in WT mice. In conclusion, the lack of endogenous ascorbate synthesis makes Gulo-/- mice more susceptible to Ni{sub 3}S{sub 2} carcinogenesis. Dietary ascorbate tends to attenuate acute toxicity of Ni{sub 3}S{sub 2} and to extend the latency of transplanted tumors. The latter effects may be of practical importance to humans and thus deserve further studies. -- Highlights: Black-Right-Pointing-Pointer Ascorbate depletion enhances carcinogenicity and acute toxicity of nickel. Black-Right-Pointing-Pointer Gulo-/- mice unable to synthesize ascorbate were used in this study. Black

  20. Effects of ascorbic acid on carcinogenicity and acute toxicity of nickel subsulfide, and on tumor transplants growth in gulonolactone oxidase knock-out mice and wild-type C57BL mice

    International Nuclear Information System (INIS)

    Kasprzak, Kazimierz S.; Diwan, Bhalchandra A.; Kaczmarek, Monika Z.; Logsdon, Daniel L.; Fivash, Mathew J.; Salnikow, Konstantin

    2011-01-01

    The aim of this study was to test a hypothesis that ascorbate depletion could enhance carcinogenicity and acute toxicity of nickel. Homozygous L-gulono- -lactone oxidase gene knock-out mice (Gulo−/− mice) unable to produce ascorbate and wild-type C57BL mice (WT mice) were injected intramuscularly with carcinogenic nickel subsulfide (Ni 3 S 2 ), and observed for the development of injection site tumors for 57 weeks. Small pieces of one of the induced tumors were transplanted subcutaneously into separate groups of Gulo−/− and WT mice and the growth of these tumors was measured for up to 3 months. The two strains of mice differed significantly with regard to (1) Ni 3 S 2 carcinogenesis: Gulo−/− mice were 40% more susceptible than WT mice; and (2) transplanted tumors development: Gulo−/− mice were more receptive to tumor growth than WT mice, but only in terms of a much shorter tumor latency; later in the exponential phase of growth, the growth rates were the same. And, with adequate ascorbate supplementation, the two strains were equally susceptible to acute toxicity of Ni 3 S 2 . Statistically significant effects of dietary ascorbate dosing levels were the following: (1) reduction in ascorbate supplementation increased acute toxicity of Ni 3 S 2 in Gulo−/− mice; (2) ascorbate supplementation extended the latency of transplanted tumors in WT mice. In conclusion, the lack of endogenous ascorbate synthesis makes Gulo−/− mice more susceptible to Ni 3 S 2 carcinogenesis. Dietary ascorbate tends to attenuate acute toxicity of Ni 3 S 2 and to extend the latency of transplanted tumors. The latter effects may be of practical importance to humans and thus deserve further studies. -- Highlights: ► Ascorbate depletion enhances carcinogenicity and acute toxicity of nickel. ► Gulo−/− mice unable to synthesize ascorbate were used in this study. ► The reduction in ascorbate levels in Gulo−/− mice increased acute toxicity induced by Ni 3 S 2 .

  1. Transport of ascorbic acid and dehydroascorbic acid by pancreatic islet cells from neonatal rats

    DEFF Research Database (Denmark)

    Zhou, A; Farver, O; Thorn, N A

    1991-01-01

    . Dehydroascorbic acid was converted to ascorbic acid by an unknown mechanism after uptake. The uptake of both ascorbic acid and dehydroascorbic acid was inhibited by tri-iodothyronine, and uptake of ascorbic acid, but not of dehydroascorbic acid, was inhibited by glucocorticoids. Isolated secretory granules...

  2. Vitamin C (ascorbic acid) requirements of Heterobranchus longifilis ...

    African Journals Online (AJOL)

    SERVER

    2007-07-04

    Jul 4, 2007 ... Fish fed the control (0 mg vitamin C kg-1) diet exhibited deficiency signs including lordosis, caudal fin deformity, ... INTRODUCTION. Vitamin C (ascorbic acid) belongs to the water-soluble group of vitamin. Its importance in fish diets and characteristics had been described by various authors. (Lim and Lovell ...

  3. Ascorbic acid, β-carotene, total phenolic compound and ...

    African Journals Online (AJOL)

    A two year study at Alexandria University compared ascorbic acid, β-carotene, total phenolic compound, nitrite content and microbiological quality of orange and strawberry fruits grown under organic and conventional management techniques to see if producers concerns are valid. Organically grown oranges and ...

  4. ASCORBIC ACID IS DECREASED IN INDUCED SPUTUM OF MILD ASTHMATICS

    Science.gov (United States)

    Asthma is primarily an airways inflammatory disease, and the bronchial airways have been shown to be particularly susceptible to oxidant-induced tissue damage. The antioxidant ascorbic acid (AA) plays an essential role in defending against oxidant attack in the airways. Decreased...

  5. Determination of ascorbic acid content of some tropical fruits by ...

    African Journals Online (AJOL)

    The ascorbic acid content of three common juicy tropical fruits, orange, water melon and cashew, were determined using iodometric titration method under three temperature regimes (refrigerated, room temperature, and heated to about 80 oC), representing the range of temperatures the fruits may be exposed to during ...

  6. Ameliorative effects of betaine and ascorbic acid administration to ...

    African Journals Online (AJOL)

    This review highlights the huge challenges heat stress pose to profitable production of broiler chickens during the hot-dry season. It also enumerates the negative effects of heat stress due to excess production of reactive oxygen species (ROS) in broiler chickens. It emphasizes that administration of betaine and/or ascorbic ...

  7. Effect of ascorbic and folic acids supplementation on oxidative ...

    African Journals Online (AJOL)

    An experiment was conducted on the effect of supplementation of ascorbic and folic acids on the oxidative hormones, enzymatic antioxidants, haematological and biochemical properties of layers exposed to increased heat load. A total of 72 Isa Brown laying hens at 31 weeks of age were randomly divided into four groups ...

  8. Chemical dosimetry by UV spectrophotometry of aqueous ascorbic acid solutions

    International Nuclear Information System (INIS)

    Alian, A.; El-Assay, N.B.; Abdel-Rehim, F.; Amin, N.E.; McLaughlin, W.L.; Roushdy, H.

    1984-01-01

    The decrease in the ultraviolet absorption of aqueous solutions of ascorbic acid brought about by large doses of gamma radiation has been investigated as a means of developing a new chemical dosimeter. Because of spontaneous ring opening under various conditions after dissolution in water, some additives were examined as possible stabilizers against such denaturing of aqueous ascorbic acid. At an ascorbic acid concentration of 10 -4 M, either 1 to 2% glycine or 0.2 M NaCl was found to be a good stabilizer. A mechanism of radiation chemistry has been proposed based on hydroxyl radical and hydroxyl adduct intermediates, leading to dehydroascorbic acid through the ascorbate complex. The optimum dosimeter solution covers an absorbed dose range approx. 50 to 350 Gy, when measured at 264 nm wavelength. The G-values for dehydroascorbic acid production were determined to be 2.94 +- 0.33 and 2.43 +- 0.11 (100 eV) -1 , with glycine and NaCl used respectively as stabilizers. (author)

  9. Ascorbic acid for the healing of skin wounds in rats

    Directory of Open Access Journals (Sweden)

    CC. Lima

    Full Text Available BACKGROUND: Healing is a complex process that involves cellular and biochemical events. Several medicines have been used in order to shorten healing time and avoid aesthetic damage. OBJECTIVE: to verify the topical effect of ascorbic acid for the healing of rats' skin wounds through the number of macrophages, new vessels and fibroblast verifications in the experimental period; and analyse the thickness and the collagen fibre organization in the injured tissue. METHODS: Male Rattus norvegicus weighing 270 ± 30 g were used. After thionembutal anesthesia, 15 mm transversal incisions were made in the animals' cervical backs. They were divided into two groups: Control Group (CG, n = 12 - skin wound cleaned with water and soap daily; Treated Group (TG, n = 12 - skin wound cleaned daily and treated with ascorbic acid cream (10%. Samples of skin were collected on the 3rd, 7th and 14th days. The sections were stained with hematoxylin-eosin and picrosirius red for morphologic analysis. The images were obtained and analysed by a Digital Analyser System. RESULTS: The ascorbic acid acted on every stage of the healing process. It reduced the number of macrophages, increased the proliferation of fibroblasts and new vessels, and stimulated the synthesis of thicker and more organized collagen fibres in the wounds when compared to CG. CONCLUSION: Ascorbic acid was shown to have anti-inflammatory and healing effects, guaranteeing a suiTable environment and conditions for faster skin repair.

  10. Plasma Ascorbic Acid and Non-Enzymatic Antioxidants Level in ...

    African Journals Online (AJOL)

    Free radicals have been implicated in the pathology of several diseases including cataract. Ascorbic acid functions as the major chain breaking antioxidant vitamin in the aqueous phase. Bilirubin, albumin and uric acid are regarded as natural antioxidants. There are conflicting reports on plasma concentrations of these ...

  11. 21 CFR 172.315 - Nicotinamide-ascorbic acid complex.

    Science.gov (United States)

    2010-04-01

    ... 172.315 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Special Dietary and Nutritional Additives § 172.315 Nicotinamide-ascorbic acid complex...

  12. Silver nanoparticles prepared in presence of ascorbic acid and ...

    Indian Academy of Sciences (India)

    Administrator

    (AgNPs) by using ascorbic acid as reducing agent and gelatin as stabilizer. ... variety of organic and inorganic reactions (Hernández-. Santos et al ... The morphology and size of the nanoparticles can be con- ... the overpotentials of many analytes that occur at unmodi- ... implemented by a copper wire lead fitted into a glass.

  13. Plasma Concentration of Ascorbic Acid and Some Hematological ...

    African Journals Online (AJOL)

    Background: Tobacco snuffing, like cigarette smoking, is known to be a common habit among the adults of Igbo communities in Nigeria. In view of the various pharmacological actions of nicotine and other additive constituents of tobacco snuff, there is growing concern that ascorbic acid, which is a vital antioxidant, and blood ...

  14. Effects of calcium gluconate and ascorbic acid on controlling shoot ...

    African Journals Online (AJOL)

    In vitro shoot necrosis is a quite widespread disorder affecting raspberry micropropagation. This study was conducted to investigate effects of calcium gluconate and ascorbic acid on shoot necrosis and dieback of raspberry shoots during micropropagation. Nodal segments of primocane-fruiting raspberry cultivars 'Allgold', ...

  15. Formulation and Evaluation of Ascorbic acid Tablets by Direct ...

    African Journals Online (AJOL)

    PURPOSE: To evaluate the tableting properties of microcrystalline starch (MCS) used as a direct compression excipient in the formulation of ascorbic acid tablets and to compare with the properties of tablets produced using microcrystalline cellulose (MCC). METHODS: MCS was obtained by partial hydrolysis of cassava ( ...

  16. Formulation and Evaluation of Ascorbic acid Tablets by Direct ...

    African Journals Online (AJOL)

    Formulation and Evaluation of Ascorbic acid Tablets by Direct Compression using Microcrystalline Starch as a Direct Compression Excipient. ... Abstract. PURPOSE: To evaluate the tableting properties of microcrystalline starch (MCS) used as a direct ... RESULTS: Mechanical properties of tablets formulated with MCS were

  17. Chromium-induced membrane damage: protective role of ascorbic acid.

    Science.gov (United States)

    Dey, S K; Nayak, P; Roy, S

    2001-07-01

    Importance of chromium as environmental toxicant is largely due to impact on the body to produce cellular toxicity. The impact of chromium and their supplementation with ascorbic acid was studied on plasma membrane of liver and kidney in male Wistar rats (80-100 g body weight). It has been observed that the intoxication with chromium (i.p.) at the dose of 0.8 mg/100 g body weight per day for a period of 28 days causes significant increase in the level of cholesterol and decrease in the level of phospholipid of both liver and kidney. The alkaline phosphatase, total ATPase and Na(+)-K(+)-ATPase activities were significantly decreased in both liver and kidney after chromium treatment, except total ATPase activity of kidney. It is suggested that chromium exposure at the present dose and duration induce for the alterations of structure and function of both liver and kidney plasma membrane. Ascorbic acid (i.p. at the dose of 0.5 mg/100 g body weight per day for period of 28 days) supplementation can reduce these structural changes in the plasma membrane of liver and kidney. But the functional changes can not be completely replenished by the ascorbic acid supplementation in response to chromium exposure. So it is also suggested that ascorbic acid (nutritional antioxidant) is useful free radical scavenger to restrain the chromium-induced membrane damage.

  18. Ameliorative effect of ascorbic acid on mercury chloride‑induced ...

    African Journals Online (AJOL)

    Introduction: Mercury is a highly toxic metal that exerts its adverse effects on the health of humans and animals through air, soil, water and food. Aim: The present study was aimed at the evaluation of the effects of ascorbic acid on mercury chloride-induced changes on the histomorphology of the spleen of adult Wistar Rats.

  19. The biochemical, physiological and therapeutic roles of ascorbic acid

    African Journals Online (AJOL)

    Ascorbic acid is an important micronutrient necessary for a significant number of metabolic reactions in humans and other primates. It is a strong reducing agent involved in reduction reaction and it is structurally related to glucose. Experimental and epidemiological studies have documented the biochemical, physiological ...

  20. Widely tunable THz synthesizer

    Science.gov (United States)

    Hindle, F.; Mouret, G.; Eliet, S.; Guinet, M.; Cuisset, A.; Bocquet, R.; Yasui, T.; Rovera, D.

    2011-09-01

    The generation of cw-THz radiation by photomixing is particularly suited to the high resolution spectroscopy of gases; nevertheless, until recently, it has suffered from a lack of frequency metrology. Frequency combs are a powerful tool that can transfer microwave frequency standards to optical frequencies and a single comb has permitted accurate (10-8) THz frequency synthesis with a limited tuning range. A THz synthesizer composed of three extended cavity laser diodes phase locked to a frequency comb has been constructed and its utility for high resolution gas phase spectroscopy demonstrated. The third laser diode allows a larger tuning range of up to 300 MHz to be achieved without the need for large frequency excursions, while the frequency comb provides a versatile link to be established from any traceable microwave frequency standard. The use of a single frequency comb as a reference for all of the cw-lasers eliminates the dependency of synthesized frequency on the carrier envelope offset frequency. This greatly simplifies the frequency comb stabilization requirements and leads to a reduced instrument complexity.

  1. SYNTH: A spectrum synthesizer

    International Nuclear Information System (INIS)

    Hensley, W.K.; McKinnon, A.D.; Miley, H.S.; Panisko, M.E.; Savard, R.M.

    1994-07-01

    A computer code has been written at the Pacific Northwest Laboratory (PNL) to synthesize the results of typical gamma-ray spectroscopy experiments. The code, dubbed SYNTH, allows a use r to specify physical characteristics of a gamma-ray source, the quantity of the nuclides producing the radiation, the source-to-detector distance and the type and thickness of absorbers, the size and composition of the detector (Ge or NaI), and the electronic set up used to gather the data. In the process of specifying the parameters needed to synthesize a spectrum, several interesting intermediate results are produced, including a photopeak transmission function vs energy, a detector efficiency curve, and a weighted list of gamma and x rays produced from a set of nuclides. All of these intermediate results are available for graphical inspection and for printing. SYNTH runs on personal computers. It is menu driven and can be customized to user specifications. SYNTH contains robust support for coaxial germanium detectors and some support for sodium iodide detectors. SYNTH is not a finished product. A number of additional developments are planned. However, the existing code has been compared carefully to spectra obtained from National Institute for Standards and Technology (NIST) certified standards with very favorable results. Examples of the use of SYNTH and several spectral results will be presented

  2. SYNTH: A spectrum synthesizer

    International Nuclear Information System (INIS)

    Hensley, W.K.; McKinnon, A.D.; Miley, H.S.; Panisko, M.E.; Savard, R.M.

    1993-10-01

    A computer code has been written at the Pacific Northwest Laboratory (PNL) to synthesize the results of typical gamma ray spectroscopy experiments. The code, dubbed SYNTH, allows a user to specify physical characteristics of a gamma ray source, the quantity of the nuclides producing the radiation, the source-to-detector distance and the presence of absorbers, the type and size of the detector, and the electronic set up used to gather the data. In the process of specifying the parameters needed to synthesize a spectrum, several interesting intermediate results are produced, including a photopeak transmission function versus energy, a detector efficiency curve, and a weighted list of gamma and x rays produced from a set of nuclides. All of these intermediate results are available for graphical inspection and for printing. SYNTH runs on personal computers. It is menu driven and can be customized to user specifications. SYNTH contains robust support for coaxial germanium detectors and some support for sodium iodide detectors. SYNTH is not a finished product. A number of additional developments are planned. However, the existing code has been compared carefully to spectra obtained from National Institute for Standards and Technology (NIST) certified standards with very favorable results. Examples of the use of SYNTH and several spectral results are presented

  3. Polymorphisms in sodium-dependent vitamin C transporter genes and plasma, aqueous humor and lens nucleus ascorbate concentrations in an ascorbate depleted setting.

    Science.gov (United States)

    Senthilkumari, Srinivasan; Talwar, Badri; Dharmalingam, Kuppamuthu; Ravindran, Ravilla D; Jayanthi, Ramamurthy; Sundaresan, Periasamy; Saravanan, Charu; Young, Ian S; Dangour, Alan D; Fletcher, Astrid E

    2014-07-01

    We have previously reported low concentrations of plasma ascorbate and low dietary vitamin C intake in the older Indian population and a strong inverse association of these with cataract. Little is known about ascorbate levels in aqueous humor and lens in populations habitually depleted of ascorbate and no studies in any setting have investigated whether genetic polymorphisms influence ascorbate levels in ocular tissues. Our objectives were to investigate relationships between ascorbate concentrations in plasma, aqueous humor and lens and whether these relationships are influenced by Single Nucleotide Polymorphisms (SNPs) in sodium-dependent vitamin C transporter genes (SLC23A1 and SLC23A2). We enrolled sixty patients (equal numbers of men and women, mean age 63 years) undergoing small incision cataract surgery in southern India. We measured ascorbate concentrations in plasma, aqueous humor and lens nucleus using high performance liquid chromatography. SLC23A1 SNPs (rs4257763, rs6596473) and SLC23A2 SNPs (rs1279683 and rs12479919) were genotyped using a TaqMan assay. Patients were interviewed for lifestyle factors which might influence ascorbate. Plasma vitamin C was normalized by a log10 transformation. Statistical analysis used linear regression with the slope of the within-subject associations estimated using beta (β) coefficients. The ascorbate concentrations (μmol/L) were: plasma ascorbate, median and inter-quartile range (IQR), 15.2 (7.8, 34.5), mean (SD) of aqueous humor ascorbate, 1074 (545) and lens nucleus ascorbate, 0.42 (0.16) (μmol/g lens nucleus wet weight). Minimum allele frequencies were: rs1279683 (0.28), rs12479919 (0.30), rs659647 (0.48). Decreasing concentrations of ocular ascorbate from the common to the rare genotype were observed for rs6596473 and rs12479919. The per allele difference in aqueous humor ascorbate for rs6596473 was -217 μmol/L, p humor ascorbate were higher for the GG genotype of rs6596473: GG, β = 1460 compared to

  4. De novo assembly and functional annotation of Myrciaria dubia fruit transcriptome reveals multiple metabolic pathways for L-ascorbic acid biosynthesis.

    Science.gov (United States)

    Castro, Juan C; Maddox, J Dylan; Cobos, Marianela; Requena, David; Zimic, Mirko; Bombarely, Aureliano; Imán, Sixto A; Cerdeira, Luis A; Medina, Andersson E

    2015-11-24

    Myrciaria dubia is an Amazonian fruit shrub that produces numerous bioactive phytochemicals, but is best known by its high L-ascorbic acid (AsA) content in fruits. Pronounced variation in AsA content has been observed both within and among individuals, but the genetic factors responsible for this variation are largely unknown. The goals of this research, therefore, were to assemble, characterize, and annotate the fruit transcriptome of M. dubia in order to reconstruct metabolic pathways and determine if multiple pathways contribute to AsA biosynthesis. In total 24,551,882 high-quality sequence reads were de novo assembled into 70,048 unigenes (mean length = 1150 bp, N50 = 1775 bp). Assembled sequences were annotated using BLASTX against public databases such as TAIR, GR-protein, FB, MGI, RGD, ZFIN, SGN, WB, TIGR_CMR, and JCVI-CMR with 75.2 % of unigenes having annotations. Of the three core GO annotation categories, biological processes comprised 53.6 % of the total assigned annotations, whereas cellular components and molecular functions comprised 23.3 and 23.1 %, respectively. Based on the KEGG pathway assignment of the functionally annotated transcripts, five metabolic pathways for AsA biosynthesis were identified: animal-like pathway, myo-inositol pathway, L-gulose pathway, D-mannose/L-galactose pathway, and uronic acid pathway. All transcripts coding enzymes involved in the ascorbate-glutathione cycle were also identified. Finally, we used the assembly to identified 6314 genic microsatellites and 23,481 high quality SNPs. This study describes the first next-generation sequencing effort and transcriptome annotation of a non-model Amazonian plant that is relevant for AsA production and other bioactive phytochemicals. Genes encoding key enzymes were successfully identified and metabolic pathways involved in biosynthesis of AsA, anthocyanins, and other metabolic pathways have been reconstructed. The identification of these genes and pathways is in agreement with

  5. Performance of structured lipids incorporating selected phenolic and ascorbic acids.

    Science.gov (United States)

    Gruczynska, Eliza; Przybylski, Roman; Aladedunye, Felix

    2015-04-15

    Conditions applied during frying require antioxidant which is stable at these conditions and provides protection for frying oil and fried food. Novel structured lipids containing nutraceuticals and antioxidants were formed by enzymatic transesterification, exploring canola oil and naturally occurring antioxidants such as ascorbic and selected phenolic acids as substrates. Lipozyme RM IM lipase from Rhizomucor miehei was used as biocatalyst. Frying performance and oxidative stability of the final transesterification products were evaluated. The novel lipids showed significantly improved frying performance compared to canola oil. Oxidative stability assessment of the structured lipids showed significant improvement in resistance to oxidative deterioration compared to original canola oil. Interestingly, the presence of ascorbic acid in an acylglycerol structure protected α-tocopherol against thermal degradation, which was not observed for the phenolic acids. Developed structured lipids containing nutraceuticals and antioxidants may directly affect nutritional properties of lipids also offering nutraceutical ingredients for food formulation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Two tomato GDP-D-mannose epimerase isoforms involved in ascorbate biosynthesis play specific roles in cell wall biosynthesis and development.

    Science.gov (United States)

    Mounet-Gilbert, Louise; Dumont, Marie; Ferrand, Carine; Bournonville, Céline; Monier, Antoine; Jorly, Joana; Lemaire-Chamley, Martine; Mori, Kentaro; Atienza, Isabelle; Hernould, Michel; Stevens, Rebecca; Lehner, Arnaud; Mollet, Jean Claude; Rothan, Christophe; Lerouge, Patrice; Baldet, Pierre

    2016-08-01

    GDP-D-mannose epimerase (GME, EC 5.1.3.18) converts GDP-D-mannose to GDP-L-galactose, and is considered to be a central enzyme connecting the major ascorbate biosynthesis pathway to primary cell wall metabolism in higher plants. Our previous work demonstrated that GME is crucial for both ascorbate and cell wall biosynthesis in tomato. The aim of the present study was to investigate the respective role in ascorbate and cell wall biosynthesis of the two SlGME genes present in tomato by targeting each of them through an RNAi-silencing approach. Taken individually SlGME1 and SlGME2 allowed normal ascorbate accumulation in the leaf and fruits, thus suggesting the same function regarding ascorbate. However, SlGME1 and SlGME2 were shown to play distinct roles in cell wall biosynthesis, depending on the tissue considered. The RNAi-SlGME1 plants harbored small and poorly seeded fruits resulting from alterations of pollen development and of pollination process. In contrast, the RNAi-SlGME2 plants exhibited vegetative growth delay while fruits remained unaffected. Analysis of SlGME1- and SlGME2-silenced seeds and seedlings further showed that the dimerization state of pectin rhamnogalacturonan-II (RG-II) was altered only in the RNAi-SlGME2 lines. Taken together with the preferential expression of each SlGME gene in different tomato tissues, these results suggest sub-functionalization of SlGME1 and SlGME2 and their specialization for cell wall biosynthesis in specific tomato tissues. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  7. Metabolic cooperation of ascorbic acid and glutathione in normal and vitamin C-deficient ODS rats.

    Science.gov (United States)

    Wang, Y; Kashiba, M; Kasahara, E; Tsuchiya, M; Sato, E F; Utsumi, K; Inoue, M

    2001-01-01

    Although the coordination of various antioxidants is important for the protection of organisms from oxidative stress, dynamic aspects of the interaction of endogenous antioxidants in vivo remain to be elucidated. We studied the metabolic coordination of two naturally occurring water-soluble antioxidants, ascorbic acid (AA) and reduced glutathione (GSH), in liver, kidney and plasma of control and scurvy-prone osteogenic disorder Shionogi (ODS) rats that hereditarily lack the ability to synthesize AA. When supplemented with AA, its levels in liver and kidney of ODS rats increased to similar levels of those in control rats. Hepato-renal levels of glutathione were similar with the two animal groups except for the slight increase in its hepatic levels in AA-supplemented ODS rats. Administration of L-buthionine sulfoximine (BSO), a specific inhibitor of GSH synthesis, rapidly decreased the hepato-renal levels of glutathione in a biphasic manner, a rapid phase followed by a slower phase. Kinetic analysis revealed that glutathione turnover was enhanced significantly in liver mitochondria and renal cytosol of ODS rats. Administration of BSO significantly increased AA levels in the liver and kidney of control rats but decreased them in AA-supplemented ODS rats. Kinetic analysis revealed that AA is synthesized by control rat liver by some BSO-enhanced mechanism and the de novo synthesized AA is transferred to the kidney. Such a coordination of the metabolism of GSH and AA in liver and kidney is suppressed in AA-deficient ODS rats. These and other results suggest that the metabolism of AA and GSH forms a compensatory network by which oxidative stress can be decreased.

  8. Control of ascorbic acid synthesis and accumulation and glutathione by the incident light red/far red ratio in Phaseolus vulgaris leaves.

    Science.gov (United States)

    Bartoli, Carlos G; Tambussi, Eduardo A; Diego, Fanello; Foyer, Christine H

    2009-01-05

    The effects of red/far red (R/FR) ratios on leaf ascorbate (AA) and glutathione (GSH) accumulation were examined in common bean (Phaseolus vulgaris L.). Growth under low R/FR ratios resulted in a "shade" phenotype and much lower leaf AA and GSH contents than high (R/FR) ratios. Photosynthesis rates were unaffected by changes in the R/FR ratio but leaf respiration rates, pyridine nucleotide pools and antioxidant enzyme activities were decreased under the low R/FR regime. The GSH pool changed slowly in response to altered R/FR ratios but leaf ascorbate acclimated over a single photoperiod. We conclude that light quality signals, particularly R/FR ratios, are important regulators of antioxidant synthesis and accumulation. These acclimatory changes are an early response to changing light environment.

  9. Suppression of radiation-induced in vitro carcinogenesis by ascorbic acid

    International Nuclear Information System (INIS)

    Tauchi, Hiroshi; Sawada, Shozo

    1993-01-01

    The effects of ascorbic acid on radiation-induced in vitro carcinogenesis have been reported using neoplastic transformation system of C3H 10T1/2 cells. In these reports, no suppressive effect on X-ray-induced transformation was observed with 6 weeks' administration of ascorbic acid (daily addition for 5 days per week) by Kennedy (1984), whereas apparent suppression was observed with daily addition for 7 days by Yasukawa et al (1989). We have tested the effects of ascorbic acid on 60 Co gamma-ray or 252 Cf fission neutron-induced transformation in Balb/c 3T3 cells. The transformation induced by both types of radiations was markedly suppressed when ascorbic acid was daily added to the medium during first 8 days of the post-irradiation period. If ascorbic acid was added for a total of 8 days but with a day's interruption in the middle, the suppression of transformation was decreased. These results suggest that continuous presence of ascorbic acid for a certain number of days is needed to suppress radiation-induced transformation. Since ascorbic acid also suppressed the promotion of radiation-induced transformation by TPA when both chemicals were added together into the medium, ascorbic acid might act on the promotion stage of transformation. Therefore, the effect of ascorbic acid on the distribution of protein kinase C activity was also investigated, and possible mechanisms of suppression of radiation-induced transformation by ascorbic acid will be discussed. (author)

  10. Ascorbate status modulates reticuloendothelial iron stores and response to deferasirox iron chelation in ascorbate-deficient rats

    DEFF Research Database (Denmark)

    Brewer, Casey; Otto-Duessel, Maya; Lykkesfeldt, Jens

    2012-01-01

    Iron chelation is essential to patients on chronic blood transfusions to prevent toxicity from iron overload and remove excess iron. Deferasirox (DFX) is the most commonly used iron chelator in the United States; however, some patients are relatively refractory to DFX therapy. We postulated...... that vitamin C supplementation would improve the availability of transfusional iron to DFX treatment by promoting iron's redox cycling, increasing its soluble ferrous form and promoting its release from reticuloendothelial cells. Osteogenic dystrophy rats (n = 54) were given iron dextran injections for 10...... 12 weeks of sham chelation. Most importantly, ascorbate supplementation at 2250 ppm improved DFX efficiency, allowing DFX to remove 21% more hepatic iron than ascorbate supplementation with 900 ppm or 150 ppm (p vitamin C status modulates the release of iron from...

  11. Production of ascorbic acid releasing biomaterials for pelvic floor repair.

    Science.gov (United States)

    Mangır, Naşide; Bullock, Anthony J; Roman, Sabiniano; Osman, Nadir; Chapple, Christopher; MacNeil, Sheila

    2016-01-01

    An underlying abnormality in collagen turnover is implied in the occurrence of complications and recurrences after mesh augmented pelvic floor repair surgeries. Ascorbic acid is a potent stimulant of collagen synthesis. The aim of this study is to produce ascorbic acid releasing poly-lactic acid (PLA) scaffolds and evaluate them for their effects on extracellular matrix production and the strength of the materials. Scaffolds which contained either l-ascorbic acid (AA) and Ascorbate-2-Phosphate (A2P) were produced with emulsion electrospinning. The release of both drugs was measured by UV spectrophotometry. Human dermal fibroblasts were seeded on scaffolds and cultured for 2weeks. Cell attachment, viability and total collagen production were evaluated as well as mechanical properties. No significant differences were observed between AA, A2P, Vehicle and PLA scaffolds in terms of fibre diameter and pore size. The encapsulation efficiency and successful release of both AA and A2P were demonstrated. Both AA and A2P containing scaffolds were significantly more hydrophilic and stronger in both dry and wet states compared to PLA scaffolds. Fibroblasts produced more collagen on scaffolds containing either AA or A2P compared to cells grown on control scaffolds. This study is the first to directly compare the two ascorbic acid derivatives in a tissue engineered scaffold and shows that both AA and A2P releasing electrospun PLA scaffolds increased collagen production of fibroblasts to similar extents but AA scaffolds seemed to be more hydrophilic and stronger compared to A2P scaffolds. Mesh augmented surgical repair of the pelvic floor currently relies on non-degradable materials which results in severe complications in some patients. There is an unmet and urgent need for better pelvic floor repair materials. Our current understanding suggests that the ideal material should be able to better integrate into sites of implantation both biologically and mechanically. The impact of

  12. Enzyme-free hydrogen peroxide sensor based on Au@Ag@C core-double shell nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yancai, E-mail: liyancai@mnnu.edu.cn [College of Chemistry & Environment, Minnan Normal University, Zhangzhou 363000 (China); Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Minnan Normal University, Zhangzhou 363000 (China); Zhang, Yayun; Zhong, Yanmei [College of Chemistry & Environment, Minnan Normal University, Zhangzhou 363000 (China); Li, Shunxing [College of Chemistry & Environment, Minnan Normal University, Zhangzhou 363000 (China); Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Minnan Normal University, Zhangzhou 363000 (China)

    2015-08-30

    Graphical abstract: - Highlights: • A facile method was designed to synthesize Au@Ag@C core-double shell nanocomposites. • Carbon nanomaterials at the outermost layer could protect Au and Ag nanoparticles from oxidation and aggregation. • The Au@Ag@C core-double shell nanocomposites showed high sensitivity and selectivity to electrocatalytic reduction of hydrogen peroxide. • The hydrogen peroxide sensor has a wide linear range of 5.0 μM to 4.75 mM and a limit of detection as low as 0.14 μM. - Abstract: The well-designed Au@Ag@C core-double shell nanocomposites were synthesized via a facile method, and were used to fabricate an enzyme-free amperometric hydrogen peroxide (H{sub 2}O{sub 2}) sensor. The size, shape, elementary composition and structure of the nanocomposites were characterized by transmission electron microscope (TEM), energy-dispersed spectrum (EDS) and X-ray diffraction (XRD). The outermost layer of the nanocomposites was amorphous carbon, the second layer was Ag and the core was Au. The Au@Ag@C core-double shell nanocomposites exhibit attractive activity for electrocatalytic reduction of H{sub 2}O{sub 2} according to the electrochemical experiments. It also demonstrates the H{sub 2}O{sub 2} sensor possess well performance with a wide linear range of 5.0 μM to 4.75 mM and a limit of detection (LOD) as low as 0.14 μM (S/N = 3). Furthermore, the interference from the common interfering species, such as glucose, ascorbic acid, dopamine and uric acid can be effectively avoided. In a word, the Au@Ag@C nanocomposites are promising candidates for enzyme-free H{sub 2}O{sub 2} sensor.

  13. Extracellular ascorbate stabilization as a result of transplasma electron transfer in Saccharomyces cerevisiae.

    Science.gov (United States)

    Santos-Ocaña, C; Navas, P; Crane, F L; Córdoba, F

    1995-12-01

    The presence of yeast cells in the incubation medium prevents the oxidation of ascrobate catalyzed by copper ions. Ethanol increases ascorbate retention. Pyrazole, an alcohol dehydrogenase inhibitor, prevents ascorbate stabilization by cells. Chelation of copper ions does not account for stabilization, since oxidation rates with broken or boiled cells or conditioned media are similar to control rates in the absence of cells. Protoplast integrity is needed to reach optimal values of stabilization. Chloroquine, a known inhibitor of plasma membrane redox systems, inhibits the ascorbate stabilization, the inhibition being partially reversed by coenzyme Q6. Chloroquine does not inhibit ferricyanide reduction. Growth of yeast in iron-deficient media to increase ferric ion reductase activity also increases the stabilization. In conclusion, extracellular ascorbate stabilization by yeast cells can reflect a coenzyme Q dependent transplasmalemma electron transfer which uses NADH as electron donor. Iron deficiency increases the ascorbate stabilization but the transmembrane ferricyanide reduction system can act independently of ascorbate stabilization.

  14. The preparation and the sustained release of titanium dioxide hollow particles encapsulating L-ascorbic acid

    Science.gov (United States)

    Tominaga, Yoko; Kadota, Kazunori; Shimosaka, Atsuko; Yoshida, Mikio; Oshima, Kotaro; Shirakawa, Yoshiyuki

    2018-05-01

    The preparation of the titanium dioxide hollow particles encapsulating L-ascorbic acid via sol-gel process using inkjet nozzle has been performed, and the sustained release and the effect protecting against degradation of L-ascorbic acid in the particles were investigated. The morphology of titanium dioxide particles was evaluated by scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). The sustained release and the effect protecting against degradation of L-ascorbic acid were estimated by dialysis bag method in phosphate buffer saline (PBS) (pH = 7.4) as release media. The prepared titanium dioxide particles exhibited spherical porous structures. The particle size distribution of the titanium dioxide particles was uniform. The hollow titanium dioxide particles encapsulating L-ascorbic acid showed the sustained release. It was also found that the degradation of L-ascorbic acid could be inhibited by encapsulating L-ascorbic acid in the titanium dioxide hollow particles.

  15. Effects of ascorbic acid, translutaminase and margarine amounts on the quality of puff pastry made from spelt flour

    Directory of Open Access Journals (Sweden)

    Šimurina Olivera D.

    2015-01-01

    Full Text Available Puff pastry has delicate and flaky texture which comes from unique combination of fat and dough. These bakery products are made from many thin layers of dough which are separated by alternate fat layers because of which they are considered to be high fat food. Properties of puff pastry depend mostly on the quality of flour, which must be specifically tailored for this purpose. The most commonly used flour in the production of puff pastry is refined wheat flour. Lately, the requirements of consumers for healthy bakery products have a great response in the baking industry. On the market there are new products made with ingredients which have high nutritional value. This paper presents an optimization of the composition of puff pastry made of spelt flour by varying the amount of ingredients such as: margarine, ascorbic acid and enzyme transglutaminase. The optimal ratio of these ingredients has been based on the consideration of their major and interaction effects. During the optimization of spelt puff pastry quality, the following goals were set: maximum volume, minimum firmness and maximum overall acceptability. The optimal solutions were in the concentration range from 3.60 mg/kg to 10 mg/kg for ascorbic acid, from 0.03 mg/kg to 3 mg/kg for transglutaminase and from 29.84 to 30% for margarine on dough basis. It is recommended that the composition of spelt puff pastry involve: 10 mg/kg ascorbic acid, 0.03 mg/kg transglutaminase and 30 % margarine on dough basis to provide the desired product characteristics.

  16. Direct electrochemistry and intramolecular electron transfer of ascorbate oxidase confined on L-cysteine self-assembled gold electrode.

    Science.gov (United States)

    Patil, Bhushan; Kobayashi, Yoshiki; Fujikawa, Shigenori; Okajima, Takeyoshi; Mao, Lanqun; Ohsaka, Takeo

    2014-02-01

    A direct electrochemistry and intramolecular electron transfer of multicopper oxidases are of a great importance for the fabrication of these enzyme-based bioelectrochemical-devices. Ascorbate oxidase from Acremonium sp. (ASOM) has been successfully immobilized via a chemisorptive interaction on the l-cysteine self-assembled monolayer modified gold electrode (cys-SAM/AuE). Thermodynamics and kinetics of adsorption of ASOM on the cys-SAM/AuE were studied using cyclic voltammetry. A well-defined redox wave centered at 166±3mV (vs. Ag│AgCl│KCl(sat.)) was observed in 5.0mM phosphate buffer solution (pH7.0) at the fabricated ASOM electrode, abbreviated as ASOM/cys-SAM/AuE, confirming a direct electrochemistry, i.e., a direct electron transfer (DET) between ASOM and cys-SAM/AuE. The direct electrochemistry of ASOM was further confirmed by taking into account the chemical oxidation of ascorbic acid (AA) by O2 via an intramolecular electron transfer in the ASOM as well as the electrocatalytic oxidation of AA at the ASOM/cys-SAM/AuE. Thermodynamics and kinetics of the adsorption of ASOM on the cys-SAM/AuE have been elaborated along with its direct electron transfer at the modified electrodes on the basis of its intramolecular electron transfer and electrocatalytic activity towards ascorbic acid oxidation and O2 reduction. ASOM saturated surface area was obtained as 2.41×10(-11)molcm(-2) with the apparent adsorption coefficient of 1.63×10(6)Lmol(-1). The ASOM confined on the cys-SAM/AuE possesses its essential enzymatic function. © 2013.

  17. Neutron scattering and HPLC study on L-ascorbic acid and its degradation

    Energy Technology Data Exchange (ETDEWEB)

    Bellocco, E. [Department of Organic and Biological Chemistry, University of Messina, Messina (Italy)], E-mail: bellocco@isengard.unime.it; Barreca, D.; Lagana, G.; Leuzzi, U. [Department of Organic and Biological Chemistry, University of Messina, Messina (Italy); Migliardo, F.; Torre, R. La; Galli, G. [Department of Physics, University of Messina, Messina (Italy); Galtieri, A. [Department of Organic and Biological Chemistry, University of Messina, Messina (Italy); Minutoli, L.; Squadrito, F. [Department of Clinical and Experimental Medicine and Pharmacology, University of Messina, Messina (Italy)

    2008-04-18

    The present paper shows a systematic dynamic and kinetic study on L-ascorbic acid and its degradation at high temperature. The neutron scattering study allows, through the behavior of quasi-elastic neutron scattering (QENS) spectra, to characterize the diffusive dynamics of L-ascorbic acid in water mixtures. Ascorbic acid undergoes degradation process at high temperature, but the presence of trehalose in solution markedly avoids ascorbic acid loss enhancing its t{sub 1/2} (half life time), as determined by high performance liquid chromatography (HPLC)

  18. A method for the determination of ascorbic acid using the iron(II)-pyridine-dimethylglyoxime complex

    International Nuclear Information System (INIS)

    Arya, S. P.; Mahajan, M.

    1998-01-01

    A simple and rapid spectrophotometric method for the determination of ascorbic acid is proposed. Ascorbic acid reduces iron (III) to iron (II) which forms a red colored complex with dimethylglyoxime in the presence of pyridine. The absorbance of the resulting solution is measured at 514 nm and a linear relationship between absorbance and concentration of ascorbic acid is observed up to 14 μg ml -1 . Studies on the interference of substances usually associated with ascorbic acid have been carried out and the applicability of the method has been tested by analysing pharmaceutical preparations of vitamin C [it

  19. Role Of Ascorbic Acid In Imparting Tolerance To Plants Against Oxidizing Pollutants

    Directory of Open Access Journals (Sweden)

    Priyanka Sharma

    2015-08-01

    Full Text Available Ascorbic acid is an antioxidant in plants which play important role in activation of many physiological and defense mechanisms. The level of ascorbic acid in plants is determinant of its tolerance against the adverse effect of oxidizing pollutants. The present study tries to relate the variation in ascorbic acid content with the tolerance and sensitivity of two selected plant species viz. Azadirachtaindica and Pongamiapinnata by calculating their Air Pollution Tolerance Index APTI during winter season from November to March in the urban city Delhi of North India. Moreover ascorbic acid is also an important part of chloroplast it protects different components of photosynthetic system from oxidative stress. Thus to understand the role of ascorbic acid in imparting tolerance to plants against oxidizing pollutants the changes in chlorophyll content of the selected plant species with variation in ambient ozone concentration was analysed. It was found that as per APTI values Azadirachta sp. came under tolerant range with highest ascorbic acid content whereas Pongamia sp. was under intermediate range with less ascorbic acid content. It was statistically established that ozone has no significant relation with chlorophyll content of Azadirachta sp. which has the highest ascorbic acid content. Whereas ambient ozone concentrations showed significant negative relation with the chlorophyll content of Pongamia sp. p 0.05. Thus it was observed that the plants with high ascorbic acid content are tolerant and have greater ability to remediate pollutants.

  20. The kinetics of oxidation of bilirubin and ascorbic acid in solution

    Science.gov (United States)

    Solomonov, A. V.; Rumyantsev, E. V.; Kochergin, B. A.; Antina, E. V.

    2012-07-01

    The results of a comparative study of the oxidation of bilirubin, ascorbic acid, and their mixture in aqueous solutions under the action of air oxygen and hydrogen peroxide are presented. The observed and true rate constants for the oxidation reactions were determined. It was shown that the oxidation of tetrapyrrole pigment occurred under these conditions bypassing the stage of biliverdin formation to monopyrrole products. Simultaneous oxidation of bilirubin and ascorbic acid was shown to be accompanied by the inhibition of ascorbic acid oxidation by bilirubin, whereas ascorbic acid itself activated the oxidation of bilirubin.

  1. Neutron scattering and HPLC study on L-ascorbic acid and its degradation

    International Nuclear Information System (INIS)

    Bellocco, E.; Barreca, D.; Lagana, G.; Leuzzi, U.; Migliardo, F.; Torre, R. La; Galli, G.; Galtieri, A.; Minutoli, L.; Squadrito, F.

    2008-01-01

    The present paper shows a systematic dynamic and kinetic study on L-ascorbic acid and its degradation at high temperature. The neutron scattering study allows, through the behavior of quasi-elastic neutron scattering (QENS) spectra, to characterize the diffusive dynamics of L-ascorbic acid in water mixtures. Ascorbic acid undergoes degradation process at high temperature, but the presence of trehalose in solution markedly avoids ascorbic acid loss enhancing its t 1/2 (half life time), as determined by high performance liquid chromatography (HPLC)

  2. Reduction of nitrobenzene with alkaline ascorbic acid: Kinetics and pathways

    International Nuclear Information System (INIS)

    Liang, Chenju; Lin, Ya-Ting; Shiu, Jia-Wei

    2016-01-01

    Highlights: • Alkaline ascorbic acid (a.k.a. vitamin C) is capable of reductively degrading NB. • The pH above the pK_a_2 of ascorbic acid increases reductive electron transfer to NB. • The rate equation for the reactions between NB and AA is determined. • NSB, AZOXY, and AZO are identified as intermediates and aniline as a final product. • Alkaline pH is essential for AA remediation of NB contaminated soils. - Abstract: Alkaline ascorbic acid (AA) exhibits the potential to reductively degrade nitrobenzene (NB), which is the simplest of the nitroaromatic compounds. The nitro group (NO_2"−) of NB has a +III oxidation state of the N atom and tends to gain electrons. The effect of alkaline pH ranging from 9 to 13 was initially assessed and the results demonstrated that the solution pH, when approaching or above the pK_a_2 of AA (11.79), would increase reductive electron transfer to NB. The rate equation for the reactions between NB and AA at pH 12 can be described as r = ((0.89 ± 0.11) × 10"−"4 mM"1"−"("a "+ "b") h"−"1) × [NB]"a "= "1"."3"5 "± "0"."1"0[AA]"b "= "0"."8"9 "± "0"."0"1. The GC/MS analytical method identified nitrosobenzene, azoxybenzene, and azobenzene as NB reduction intermediates, and aniline (AN) as a final product. These experimental results indicate that the alkaline AA reduction of NB to AN mainly proceeds via the direct route, consisting of a series of two-electron or four-electron transfers, and the condensation reaction plays a minor route. Preliminary evaluation of the remediation of spiked NB contaminated soils revealed that maintenance of alkaline pH and a higher water to soil ratio are essential for a successful alkaline AA application.

  3. Application of ascorbic acid 2-phosphate as a new voltammetric substrate for alkaline phosphatase determination in human serum

    Directory of Open Access Journals (Sweden)

    Wei Sun

    2005-12-01

    Full Text Available An electrochemical assay of the enzyme alkaline phosphatase (ALP using ascorbic acid 2-phosphate (AAP as a new voltammetric substrate has been described in this paper. In the alkaline buffer solution the ALP enzymatic hydrolysis product of AAP was ascorbic acid (AA, which was an electro-active substance and had a sensitive differential pulse voltammetric (DPV oxidative response on glassy carbon electrode (GCE at +380 mV (versus Ag/AgCl, so the activity of ALP could be monitored voltammetrically of the oxidative peak current of AA. The electrochemical behaviours of AA were carefully studied and the AA standard solution could be measured by DPV method in the linear range from 10.0 to 1000.0 μmol/L with the detection limit of 8.0 μmol/L. The optimal conditions for ALP enzymatic reaction and the voltammetric detection were optimized. Under the optimal conditions the calibration curve for ALP assay exhibited a linear range from 0.4 to 2000.0 U/L with a detection limit of 0.3 U/L. This proposed method was further applied to determine the ALP content in healthy human serum and the results were in good agreement with the traditional p-nitrophenyl phosphate spectrophotometric method. The kinetic constants of enzymatic reaction were also investigated with the apparent kinetic constant Km as 2.77 mmol/L and the maximum velocity Vmax as 0.33 mol/min.

  4. D-penicillamine-templated copper nanoparticles via ascorbic acid reduction as a mercury ion sensor.

    Science.gov (United States)

    Lin, Shu Min; Geng, Shuo; Li, Na; Li, Nian Bing; Luo, Hong Qun

    2016-05-01

    Mercury ion is one of the most hazardous metal pollutants that can cause deleterious effects on human health and the environment even at low concentrations. It is necessary to develop new mercury detection methods with high sensitivity, specificity and rapidity. In this study, a novel and green strategy for synthesizing D-penicillamine-capped copper nanoparticles (DPA-CuNPs) was successfully established by a chemical reduction method, in which D-penicillamine and ascorbic acid were used as stabilizing agent and reducing agent, respectively. The as-prepared DPA-CuNPs showed strong red fluorescence and had a large Stoke's shift (270nm). Scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, fluorescence spectroscopy, and ultraviolet-visible spectrophotometry were utilized to elucidate the possible fluorescence mechanism, which could be aggregation-induced emission effect. Based on the phenomenon that trace mercury ion can disperse the aggregated DPA-CuNPs, resulting in great fluorescence quench of the system, a sensitive and selective assay for mercury ion in aqueous solution with the DPA-CuNPs was developed. Under optimum conditions, this assay can be applied to the quantification of Hg(2+) in the 1.0-30μM concentration range and the detection limit (3σ/slope) is 32nM. The method was successfully applied to determine Hg(2+) in real water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Simultaneous determination of ascorbic acid, dopamine and uric acid based on tryptophan functionalized graphene

    International Nuclear Information System (INIS)

    Lian, Qianwen; He, Zhifang; He, Qian; Luo, Ai; Yan, Kaiwang; Zhang, Dongxia; Lu, Xiaoquan; Zhou, Xibin

    2014-01-01

    Highlights: • Trp-GR was synthesized by utilizing a facile ultrasonic method. • The material as prepared had well dispersivity in water and better conductivity than pure GR. • Trp-GR/GCE showed excellent potential for the determination of AA, DA and UA. • The proposed method was applied for the analysis of AA, DA and UA in real samples. - Abstract: A new type of tryptophan-functionalized graphene nanocomposite (Trp-GR) was synthesized by utilizing a facile ultrasonic method via π–π conjugate action between graphene (GR) and tryptophan (Trp) molecule. The material as prepared had well dispersivity in water and better conductivity than pure GR. The surface morphology of Trp-GR was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The electrochemical behaviors of ascorbic acid (AA), dopamine (DA), and uric acid (UA) were investigated by cyclic voltammetry (CV) on the surface of Trp-GR. The separation of the oxidation peak potentials for AA–DA, DA–UA and UA–AA was about 182 mV, 125 mV and 307 mV, which allowed simultaneously determining AA, DA, and UA. Differential pulse voltammetery (DPV) was used for the determination of AA, DA, and UA in their mixture. Under optimum conditions, the linear response ranges for the determination of AA, DA, and UA were 0.2–12.9 mM, 0.5–110 μM, and 10–1000 μM, with the detection limits (S/N = 3) of 10.09 μM, 0.29 μM and 1.24 μM, respectively. Furthermore, the modified electrode was investigated for real sample analysis

  6. Simultaneous determination of ascorbic acid, dopamine and uric acid based on tryptophan functionalized graphene

    Energy Technology Data Exchange (ETDEWEB)

    Lian, Qianwen; He, Zhifang; He, Qian; Luo, Ai; Yan, Kaiwang; Zhang, Dongxia [Key Laboratory of Bioelectrochemistry and Environmental Analysis of Gansu Province, College of Geography and Environment Science, Northwest Normal University, Lanzhou, 730070 (China); Lu, Xiaoquan, E-mail: Luxq@nwnu.edu.cn [Key Laboratory of Bioelectrochemistry and Environmental Analysis of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, 730070 (China); Zhou, Xibin, E-mail: zhouxb@nwnu.edu.cn [Key Laboratory of Bioelectrochemistry and Environmental Analysis of Gansu Province, College of Geography and Environment Science, Northwest Normal University, Lanzhou, 730070 (China)

    2014-05-01

    Highlights: • Trp-GR was synthesized by utilizing a facile ultrasonic method. • The material as prepared had well dispersivity in water and better conductivity than pure GR. • Trp-GR/GCE showed excellent potential for the determination of AA, DA and UA. • The proposed method was applied for the analysis of AA, DA and UA in real samples. - Abstract: A new type of tryptophan-functionalized graphene nanocomposite (Trp-GR) was synthesized by utilizing a facile ultrasonic method via π–π conjugate action between graphene (GR) and tryptophan (Trp) molecule. The material as prepared had well dispersivity in water and better conductivity than pure GR. The surface morphology of Trp-GR was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The electrochemical behaviors of ascorbic acid (AA), dopamine (DA), and uric acid (UA) were investigated by cyclic voltammetry (CV) on the surface of Trp-GR. The separation of the oxidation peak potentials for AA–DA, DA–UA and UA–AA was about 182 mV, 125 mV and 307 mV, which allowed simultaneously determining AA, DA, and UA. Differential pulse voltammetery (DPV) was used for the determination of AA, DA, and UA in their mixture. Under optimum conditions, the linear response ranges for the determination of AA, DA, and UA were 0.2–12.9 mM, 0.5–110 μM, and 10–1000 μM, with the detection limits (S/N = 3) of 10.09 μM, 0.29 μM and 1.24 μM, respectively. Furthermore, the modified electrode was investigated for real sample analysis.

  7. Antioxidant poly(lactic-co-glycolic) acid nanoparticles made with α-tocopherol-ascorbic acid surfactant.

    Science.gov (United States)

    Astete, Carlos E; Dolliver, Debra; Whaley, Meocha; Khachatryan, Lavrent; Sabliov, Cristina M

    2011-12-27

    The goal of the study was to synthesize a surfactant made of α-tocopherol (vitamin E) and ascorbic acid (vitamin C) of antioxidant properties dubbed as EC, and to use this surfactant to make poly(lactic-co-glycolic) acid (PLGA) nanoparticles. Self-assembled EC nanostructures and PLGA-EC nanoparticles were made by nanoprecipitation, and their physical properties (size, size distribution, morphology) were studied at different salt concentrations, surfactant concentrations, and polymer/surfactant ratios. EC surfactant was shown to form self-assembled nanostructures in water with a size of 22 to 138 nm in the presence of sodium chloride, or 12 to 31 nm when synthesis was carried out in sodium bicarbonate. Polymeric PLGA-EC nanoparticles presented a size of 90 to 126 nm for 40% to 120% mass ratio PLGA to surfactant. For the same mass ratios, the PLGA-Span80 formed particles measured 155 to 216 nm. Span80 formed bilayers, whereas EC formed monolayers at the interfaces. PLGA-EC nanoparticles and EC showed antioxidant activity based on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay measurements using UV and EPR techniques, antioxidant activity which is not characteristic to commercially available Span80. The thiobarbituric acid reactive substances (TBARS) assay for lipid peroxidation showed that PLGA nanoparticles with EC performed better as antioxidants than the EC nanoassembly or the free vitamin C. Nanoparticles were readily internalized by HepG2 cells and were localized in the cytoplasm. The newly synthesized EC surfactant was therefore found successful in forming uniform, small size polymeric nanoparticles of intrinsic antioxidant properties.

  8. Ascorbic acid and melatonin reduce heat-induced performance inhibition and oxidative stress in Japanese quails.

    Science.gov (United States)

    Sahin, N; Onderci, M; Sahin, K; Gursu, M F; Smith, M O

    2004-02-01

    1. The effects of ascorbic acid (L-ascorbic acid) and melatonin supplementation on performance, carcase characteristics, malondialdehyde (MDA) as lipid peroxidation indicator, ascorbic acid, retinol, tocopherol and mineral status in the Japanese quail (Coturnix coturnix japonica) exposed to high ambient temperature were evaluated. 2. Two hundred and forty Japanese quails (10 d old) were randomly assigned to 8 treatment groups consisting of 10 replicates of three birds each. The birds were kept in a temperature-controlled room at 22 degrees C (Thermoneutral, TN groups) or 34 degrees C (for 8 h/d; 09:00 to 17:00 h; Heat stress, HS groups). Birds in both TN and HS were fed either a basal (control) diet or the basal diet supplemented with 250 mg of L-ascorbic acid/kg of diet (Ascorbic acid group), 40 mg of melatonin/kg of diet (Melatonin group) or both (Ascorbic acid + Melatonin group). 3. Supplementing heat-stressed quails with ascorbic acid and melatonin improved performance compared with the control group. Effects generally were greatest in quails supplemented with both ascorbic acid and melatonin. 4. Although supplementation did not consistently restore the concentrations of serum ascorbic acid, retinol and tocopherol to those of TN groups, these concentrations increased significantly with supplementation. Furthermore, serum and liver MDA and serum cholesterol and glucose concentrations were lower in the supplemented groups than in the heat-stressed controls. 5. Within each environment, excretion of Ca, P, Mg, Zn, Fe and Cr were lowest in the combination group and, in all cases, highest in the HS group. Interactions between diet and temperature were detected for live weight gain, cold carcase weight, MDA, ascorbic acid, tocopherol concentrations and excretion of zinc. 6. The results of the study indicate that ascorbic acid and melatonin supplementation attenuate the decline in performance and antioxidant and mineral status caused by heat stress and such

  9. Peroxidase enzymes regulate collagen extracellular matrix biosynthesis.

    Science.gov (United States)

    DeNichilo, Mark O; Panagopoulos, Vasilios; Rayner, Timothy E; Borowicz, Romana A; Greenwood, John E; Evdokiou, Andreas

    2015-05-01

    Myeloperoxidase and eosinophil peroxidase are heme-containing enzymes often physically associated with fibrotic tissue and cancer in various organs, without any direct involvement in promoting fibroblast recruitment and extracellular matrix (ECM) biosynthesis at these sites. We report herein novel findings that show peroxidase enzymes possess a well-conserved profibrogenic capacity to stimulate the migration of fibroblastic cells and promote their ability to secrete collagenous proteins to generate a functional ECM both in vitro and in vivo. Mechanistic studies conducted using cultured fibroblasts show that these cells are capable of rapidly binding and internalizing both myeloperoxidase and eosinophil peroxidase. Peroxidase enzymes stimulate collagen biosynthesis at a post-translational level in a prolyl 4-hydroxylase-dependent manner that does not require ascorbic acid. This response was blocked by the irreversible myeloperoxidase inhibitor 4-amino-benzoic acid hydrazide, indicating peroxidase catalytic activity is essential for collagen biosynthesis. These results suggest that peroxidase enzymes, such as myeloperoxidase and eosinophil peroxidase, may play a fundamental role in regulating the recruitment of fibroblast and the biosynthesis of collagen ECM at sites of normal tissue repair and fibrosis, with enormous implications for many disease states where infiltrating inflammatory cells deposit peroxidases. Copyright © 2015 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  10. Effects of cytochalasin B on the uptake of ascorbic acid and glucose by 3T3 fibroblasts: Mechanism of impaired ascorbate transport in diabetes

    International Nuclear Information System (INIS)

    Fay, M.J.; Bush, M.J.; Verlangieri, A.J.

    1990-01-01

    Hyperglycemia and/or hypoinsulinemia have been found to inhibit L-ascorbic acid cellular transport. The resultant decrease in intracellular ascorbic acid may de-inhibit aryl sulfatase B and increase degradation of sulfated glycosaminoglycans (sGAG). This could lead to a degeneration of the extracellular matrix and result in increased intimal permeability, the initiating event in atherosclerosis. The present studies show that the glucose transport inhibitor cytochalasin B blocked the uptake of 3 H-2-deoxy-D-glucose by mouse 3T3 fibroblasts. Cytochalasin B also blocked the uptake of 14 C-L-ascorbic acid. The results of these studies further support the hypothesis that glucose and ascorbate share a common transport system. This may have important implications concerning the vascular pathology associated with diabetes mellitus

  11. [Facultative and obligate aerobic methylobacteria synthesize cytokinins].

    Science.gov (United States)

    Ivanova, E G; Doronina, N V; Shepeliakovskaia, A O; Laman, A G; Brovko, F A; Trotsenko, Iu A

    2000-01-01

    The presence and expression of genes controlling the synthesis and secretion of cytokinins by the pink-pigmented facultative methylotroph Methylobacterium mesophilicum VKM B-2143 with the serine pathway and nonpigmented obligate methylotroph Methylovorus mays VKM B-2221 with the ribulose monophosphate pathway of C1 metabolism were shown using the polymerase chain reaction (PCR) and reverse transcription-PCR methods. The presence of the corresponding mRNA in M. mesophilicum cells grown on methanol or succinate suggests that the expression of these genes is constitutive. The cytokinin activity of culture liquid and its fractions was determined by a biotest with Amarantus caudatus L. seedlings. Using enzyme-linked immunosorbent analysis, we detected zeatin (riboside) in the culture liquid of both bacteria studied. The data obtained show that the aerobic methylobacteria are phytosymbionts that are able to utilize the single- and polycarbon compounds secreted by symbiotic plants and to synthesize cytokinins.

  12. Fully automated parallel oligonucleotide synthesizer

    Czech Academy of Sciences Publication Activity Database

    Lebl, M.; Burger, Ch.; Ellman, B.; Heiner, D.; Ibrahim, G.; Jones, A.; Nibbe, M.; Thompson, J.; Mudra, Petr; Pokorný, Vít; Poncar, Pavel; Ženíšek, Karel

    2001-01-01

    Roč. 66, č. 8 (2001), s. 1299-1314 ISSN 0010-0765 Institutional research plan: CEZ:AV0Z4055905 Keywords : automated oligonucleotide synthesizer Subject RIV: CC - Organic Chemistry Impact factor: 0.778, year: 2001

  13. Pharmacological ascorbate and ionizing radiation (IR increase labile iron in pancreatic cancer

    Directory of Open Access Journals (Sweden)

    Justin C. Moser

    2014-01-01

    Full Text Available Labile iron, i.e. iron that is weakly bound and is relatively unrestricted in its redox activity, has been implicated in both the pathogenesis as well as treatment of cancer. Two cancer treatments where labile iron may contribute to their mechanism of action are pharmacological ascorbate and ionizing radiation (IR. Pharmacological ascorbate has been shown to have tumor-specific toxic effects due to the formation of hydrogen peroxide. By catalyzing the oxidation of ascorbate, labile iron can enhance the rate of formation of hydrogen peroxide; labile iron can also react with hydrogen peroxide. Here we have investigated the magnitude of the labile iron pool in tumor and normal tissue. We also examined the ability of pharmacological ascorbate and IR to change the size of the labile iron pool. Although a significant amount of labile iron was seen in tumors (MIA PaCa-2 cells in athymic nude mice, higher levels were seen in murine tissues that were not susceptible to pharmacological ascorbate. Pharmacological ascorbate and irradiation were shown to increase the labile iron in tumor homogenates from this murine model of pancreatic cancer. As both IR and pharmacological ascorbate may rely on labile iron for their effects on tumor tissues, our data suggest that pharmacological ascorbate could be used as a radio-sensitizing agent for some radio-resistant tumors.

  14. Ascorbic acid effects on in vitro maturation of mouse oocyte with or ...

    African Journals Online (AJOL)

    Ascorbic acid has long been associated with fertility. This study was designed to determine the effects of ascorbic acid on in vitro maturation of mouse oocyte with or without cumulus cells. In this study, 508 denuded oocytes (DOs) and 527 cumulus–oocyte complexes (COCs) from mice stimulated with pregnant mare's serum ...

  15. Mechanism of ascorbic acid interference in biochemical tests that use peroxide and peroxidase to generate chromophore.

    Science.gov (United States)

    Martinello, Flávia; Luiz da Silva, Edson

    2006-11-01

    Ascorbic acid interferes negatively in peroxidase-based tests (Trinder method). However, the precise mechanism remains unclear for tests that use peroxide, a phenolic compound and 4-aminophenazone (4-AP). We determined the chemical mechanism of this interference, by examining the effects of ascorbic acid in the reaction kinetics of the production and reduction of the oxidized chromophore in urate, cholesterol, triglyceride and glucose tests. Reaction of ascorbic acid with the Trinder method constituents was also verified. Ascorbic acid interfered stoichiometrically with all tests studied. However, it had two distinct effects on the reaction rate. In the urate test, ascorbic acid decreased the chromophore formation with no change in its production kinetics. In contrast, in cholesterol, triglyceride and glucose tests, an increase in the lag phase of color development occurred. Of all the Trinder constituents, only peroxide reverted the interference. In addition, ascorbic acid did not interfere with oxidase activity nor reduce significantly the chromophore formed. Peroxide depletion was the predominant chemical mechanism of ascorbic acid interference in the Trinder method with phenolics and 4-AP. Distinctive effects of ascorbic acid on the reaction kinetics of urate, cholesterol, glucose and triglyceride might be due to the rate of peroxide production by oxidases.

  16. Control of lethal browning by using ascorbic acid on shoot tip ...

    African Journals Online (AJOL)

    The use of ascorbic acid during explants preparation and the effect of different concentrations of ascorbic acid in controlling lethal browning and survival of the explants in local banana cv. Mzuzu banana were investigated. The explants were taken from young suckers. The shoot tips were cultured on Murashige and Skoog's ...

  17. Ascorbic acid metabolism in the organism under the lack of oxygen supply to the tissues

    Directory of Open Access Journals (Sweden)

    Sergiy Petrov

    2017-06-01

    Full Text Available The number and ratios of the metabolites of vitamin C - ascorbic, dehydroascorbic and diketogulonic acids were studied under the action of closed space hypoxia, acute blood loss and during sleep – the conditions associated with various oxygen saturation of the organism. It was found that in case of closed space hypoxia, the level of ascorbic and diketogulonic acid decreased with a simultaneous increase in the content of dehydroascorbic acid in the heart and brain. Acute blood loss resulted in decrease in the level of all metabolites of ascorbic acid. During sleep, the level of ascorbic acid metabolites increased. The ratio of vitamin-active metabolites to vitamin-inactive form of ascorbic acid in case of closed space hypoxia and acute blood loss decreased, and during sleep – it did not change significantly.

  18. Salivary ascorbic acid levels in betel quid chewers: A biochemical study

    Directory of Open Access Journals (Sweden)

    Shishir R Shetty

    2013-01-01

    Full Text Available Background: Quid chewing practice has been a part of our tradition since centuries with little known evidence of oral cancer. However, recent trends show a rise in occurrence of oral cancer often associated with tobacco and arecanut usage. Ascorbic acid is an important salivary antioxidant. Betel leaf which is used in quid is known to contain ascorbic acid. Aim: The aim of our study was to assess the salivary levels of ascorbic acid in traditional quid chewers so as to determine whether the betel leaf has protective antioxidant action. Materials and Methods: Salivary ascorbic acid levels of 60 subjects were estimated using the Dinitrophenyl hydrazine method. Results: The results revealed that quid chewers who used betel leaf had higher salivary ascorbic acid content compared to nonbetel leaf quid chewers. This could possibly be due to the protective antioxidants in the betel leaf.

  19. Salivary ascorbic acid levels in betel quid chewers: A biochemical study.

    Science.gov (United States)

    Shetty, Shishir R; Babu, Subhas; Kumari, Suchetha; Prasad, Rajendra; Bhat, Supriya; Fazil, K A

    2013-07-01

    Quid chewing practice has been a part of our tradition since centuries with little known evidence of oral cancer. However, recent trends show a rise in occurrence of oral cancer often associated with tobacco and arecanut usage. Ascorbic acid is an important salivary antioxidant. Betel leaf which is used in quid is known to contain ascorbic acid. The aim of our study was to assess the salivary levels of ascorbic acid in traditional quid chewers so as to determine whether the betel leaf has protective antioxidant action. Salivary ascorbic acid levels of 60 subjects were estimated using the Dinitrophenyl hydrazine method. The results revealed that quid chewers who used betel leaf had higher salivary ascorbic acid content compared to nonbetel leaf quid chewers. This could possibly be due to the protective antioxidants in the betel leaf.

  20. Characterization and engineering of thermophilic aldolases : synthesizing nitrogen-heterocycles in biosynthetic routes

    NARCIS (Netherlands)

    Wolterink-van Loo, S.

    2009-01-01

    Aldolases are enzymes that catalyze reactions in both degradation and biosynthetic pathways in vivo and have been discovered in all domains of life. they. An interesting property of aldolases is that they can synthesize carbon-carbon bonds, generating a new stereogenic centre. As enzymes are

  1. Degradation of L-Ascorbic Acid in the Amorphous Solid State.

    Science.gov (United States)

    Sanchez, Juan O; Ismail, Yahya; Christina, Belinda; Mauer, Lisa J

    2018-03-01

    Ascorbic acid degradation in amorphous solid dispersions was compared to its degradation in the crystalline state. Physical blends and lyophiles of ascorbic acid and polymers (pectins and polyvinylpyrrolidone [PVP]) were prepared initially at 50:50 (w/w), with further studies using the polymer that best inhibited ascorbic acid crystallization in the lyophiles in 14 vitamin : PVP ratios. Samples were stored in controlled environments (25 to 60 °C, 0% to 23% RH) for 1 mo and analyzed periodically to track the physical appearance, change in moisture content, physical state (powder x-ray diffraction and polarized light microscopy), and vitamin loss (high performance liquid chromatography) over time. The glass transition temperatures of select samples were determined using differential scanning calorimetry, and moisture sorption profiles were generated. Ascorbic acid in the amorphous form, even in the glassy amorphous state, was more labile than in the crystalline form in some formulations at the highest storage temperature. Lyophiles stored at 25 and 40 °C and those in which ascorbic acid had crystallized at 60 °C (≥70% ascorbic acid : PVP) had no significant difference in vitamin loss (P > 0.05) relative to physical blend controls, and the length of storage had little effect. At 60 °C, amorphous ascorbic acid lyophiles (≤60% ascorbic acid : PVP) lost significantly more vitamin (P vitamin loss significantly increased over time. In these lyophiles, vitamin degradation also significantly increased (P vitamins are naturally present or added at low concentrations and production practices may promote amorphization of the vitamin. Vitamin C is one of the most unstable vitamins in foods. This study documents that amorphous ascorbic acid is less stable than crystalline ascorbic acid in some environments (for example, higher temperatures within 1 wk), especially when the vitamin is present at low concentrations in a product. These findings increase the understanding of

  2. Increasing Thai Catfish's Immunity (Pangasius hypophthalmus Fowler Using Ascorbic Acid

    Directory of Open Access Journals (Sweden)

    , Ilmiah

    2007-08-01

    Full Text Available ABSTRACTAn experiment to determine Thai catfish's (Pangasius hypophthalmus Fowler immunity was carried out using different levels of ascorbic acid (0, 1.000, 2.000 and 3.000 mg/kg feed.  Fish of 15-20 g in weight were kept in aquaria for 6 weeks with density of 15 fish/aquaria.  Feed was given at 5-10 % of total biomass with frequency of three times a day.  The blood sampling was taken every week and the challenge test with Aeromonas hydrophila (106cells/mm3 injection intramuscular was done on the 30th day.   The result of this experiment shown that feed with ascorbic acid of 2.000 mg/kg was elevated the cellular responses such as: leucocyte total (34.850 cels/mm3, differential of leucocyte (lymphocyte: 72,2%, monocyte: 8,0%, neutrophyl: 7,8%, phagocytic index (13% and humoral response (titre antibody: 0.829 serum aglutination unit, which at the same time proves high level of survival rate against the artificial injection using A. hydrophila. Key words :  Ascorbic acid, fish immunity, Thai catfish, Pangasius hypophthalmus.   ABSTRAK Suatu penelitian telah dilakukan di laboratorium dengan menggunakan ikan jambal Siam (Pangasius hypophthalmus Fowler untuk melihat tingkat kekebalan ikan dengan menambahkan vitamin C pada pakan (0, 1.000, 2.000 dan 3.000 mg/kg pakan.  Ikan jambal Siam ukuran 15-20 g dipelihara dalam aquarium selama 6 minggu dengan kepadatan 15 ekor/wadah.  Pemberian pakan dilakukan 3 kali sehari sebanyak 5-10% dari bobot biomasa, pengambilan contoh darah dilakukan setiap minggu dan uji tantang dilakukan pada hari ke-30 dengan bakteri Aeromonas hydrophila (106 sel/mm3 secara intramuskular.  Hasil penelitian menunjukkan bahwa penambahan vitamin C sebanyak 2.000 mg/kg pakan menyebabkan meningkatnya respon seluler antara lain: total lekosit (34.850 sel/mm3, jenis lekosit (limfosit: 72,2%, monosit: 8,0%, netrofil: 7,7% dan trombosit: 17,6% indeks fagositik 13% dan respon humoral (titer antibodi: 0,829 unit serum aglutinasi

  3. Reduction of nitrobenzene with alkaline ascorbic acid: Kinetics and pathways

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Chenju, E-mail: cliang@nchu.edu.tw [Department of Environmental Engineering, National Chung Hsing University 250, Kuo-kuang Road, Taichung 402, Taiwan (China); Lin, Ya-Ting [Department of Environmental Engineering, Chung Yuan Christian University, 200 Chung Pei Road, Chung Li District, Taoyuan City 320, Taiwan (China); Shiu, Jia-Wei [Department of Environmental Engineering, National Chung Hsing University 250, Kuo-kuang Road, Taichung 402, Taiwan (China)

    2016-01-25

    Highlights: • Alkaline ascorbic acid (a.k.a. vitamin C) is capable of reductively degrading NB. • The pH above the pK{sub a2} of ascorbic acid increases reductive electron transfer to NB. • The rate equation for the reactions between NB and AA is determined. • NSB, AZOXY, and AZO are identified as intermediates and aniline as a final product. • Alkaline pH is essential for AA remediation of NB contaminated soils. - Abstract: Alkaline ascorbic acid (AA) exhibits the potential to reductively degrade nitrobenzene (NB), which is the simplest of the nitroaromatic compounds. The nitro group (NO{sub 2}{sup −}) of NB has a +III oxidation state of the N atom and tends to gain electrons. The effect of alkaline pH ranging from 9 to 13 was initially assessed and the results demonstrated that the solution pH, when approaching or above the pK{sub a2} of AA (11.79), would increase reductive electron transfer to NB. The rate equation for the reactions between NB and AA at pH 12 can be described as r = ((0.89 ± 0.11) × 10{sup −4} mM{sup 1−(a} {sup +} {sup b)} h{sup −1}) × [NB]{sup a} {sup =} {sup 1.35} {sup ±} {sup 0.10}[AA]{sup b} {sup =} {sup 0.89} {sup ±} {sup 0.01}. The GC/MS analytical method identified nitrosobenzene, azoxybenzene, and azobenzene as NB reduction intermediates, and aniline (AN) as a final product. These experimental results indicate that the alkaline AA reduction of NB to AN mainly proceeds via the direct route, consisting of a series of two-electron or four-electron transfers, and the condensation reaction plays a minor route. Preliminary evaluation of the remediation of spiked NB contaminated soils revealed that maintenance of alkaline pH and a higher water to soil ratio are essential for a successful alkaline AA application.

  4. Effect of ascorbate ions in DTPA treatment after contamination by mixed plutonium dioxide-sodium burning products

    International Nuclear Information System (INIS)

    Metivier, H.; Masse, R.; Nolibe, D.; Nenot, J.C.; Lafuma, J.

    1977-01-01

    Plutonium toxicity problems arising from the use of molten sodium cooled fast breeder reactors involving the accidental mixing and ignition of sodium contaminated by plutonium dioxide have been investigated. The possibility of using the strong reducing agent, ascorbate ion, in order to reduce Pu VI to a chemical form more complexable by DTPA, has been tested using male and female rats. Urine, feces, liver and skeletal measurements of 239 Pu daughter products were carried out. It was shown that the transportable fraction was not significantly modified by the associate ascorbate-DTPA treatment. However the skeletal burden which represents 2.2% with DTPA, reached only 1.6% with ascorbate association and 0.3% with preventive ascorbate injections. Whatever the DTPA ascorbate treatment, the liver burden was not modified significantly. Difference observable only with preventive ascorbate treatment cancels out ascorbate association in order to greatly increase DTPA therapy efficiency, but seems to indicate that the Pu-proteins associations in blood is reduced more easily by ascorbate than association of Pu with local proteins. Ascorbate reduction can also be observed in urinary elimination in that preventive ascorbate, followed by DTPA-ascorbate, leads to a quicker urinary elimination than DTPA or DTPA plus ascorbate post treatment. (U.K.)

  5. CITOGENETICS EFFECTS INDUCED BY THE ASCORBIC ACID TREATMENT OF LARIX DECIDUA MILL. SSP. CARPATICA AND PICEA ABIES (L. KARST

    Directory of Open Access Journals (Sweden)

    Ioana Ieremia

    2006-08-01

    Full Text Available The paper present the influence of ascorbic acid upon the mitotic division of Larix decidua Mill ssp. carpatica and Picea abies (L. Karst. The treatment is applied of two variants, germinated seed in ascorbic acid (variantAand germinated seeds in disttilate water, than treated with ascorbic acid in 3 concentrations (variant B.

  6. Enzyme detection by microfluidics

    DEFF Research Database (Denmark)

    2013-01-01

    Microfluidic-implemented methods of detecting an enzyme, in particular a DNA-modifying enzyme, are provided, as well as methods for detecting a cell, or a microorganism expressing said enzyme. The enzyme is detected by providing a nucleic acid substrate, which is specifically targeted...... by that enzyme...

  7. In vivo inhibition of tumor progression by 5 hydroxy-1,4-naphthoquinone (juglone) and 2-(4-hydroxyanilino)-1,4-naphthoquinone (Q7) in combination with ascorbate

    Energy Technology Data Exchange (ETDEWEB)

    Ourique, Fabiana [Department of Biochemistry, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC (Brazil); Kviecinski, Maicon R. [Postgraduate Programe of Health Science, Universidade do Sul de Santa Catarina (UNISUL), Palhoça, SC (Brazil); Zirbel, Guilherme; Castro, Luiza S.E.P.W.; Gomes Castro, Allisson Jhonatan; Mena Barreto Silva, Fátima Regina [Department of Biochemistry, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC (Brazil); Valderrama, Jaime A.; Rios, David; Benites, Julio [Department of Chemical and Pharmaceutical Sciences, Universidad Arturo Prat, Iquique (Chile); Calderon, Pedro Buc [Toxicology and Cancer Biology Research Group (GTOX), Louvain Drug Research Institute, Université Catholique de Louvain, Brussels (Belgium); Pedrosa, Rozangela Curi, E-mail: rozangelapedrosa@gmail.com [Department of Biochemistry, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC (Brazil)

    2016-09-02

    The purpose of the study was to obtain further in vivo data of antitumor effects and mechanisms triggered by juglone and Q7 in combination with ascorbate. The study was done using Ehrlich ascites tumor-bearing mice. Treatments were intraperitoneal every 24 h for 9 days. Control group was treated with excipient. Previous tests selected the doses of juglone and Q7 plus ascorbate (1 and 100 mg/kg, respectively). Samples of ascitic fluid were collected to evaluate carbonyl proteins, GSH and activity of antioxidant enzymes such as catalase, superoxide dismutase, glutathione peroxidase and glutathione reductase. Hypoxia inducible factor HIF-1α, GLUT1, proteins driving cell cycle (p53, p16 and cyclin A) and apoptosis (poly-ADP-polymerase PARP, Bax and Bcl-xL) were assessed by western blot. Tumor cells were categorized by the phase of cell cycle using flow cytometry and type of cell death using acridine orange/ethidium bromide. A glucose uptake assessment was performed by liquid scintillation using Ehrlich tumor cells cultured with {sup 14}C-deoxyglucose. Treatments caused increased protein carbonylation and activity of antioxidant enzymes and decreased levels of GSH, HIF-1α, GLUT1 and glucose uptake in tumor cells. They also caused increased number of tumor cells in G1, p53 and p16 activation and decreased cyclin A, but only when combined with ascorbate. Apoptosis was induced mostly when treatments were done with ascorbate, causing PARP and Bax cleavage, and increased Bax/Bcl-xL ratio. Juglone and Q7 in combination with ascorbate caused inhibition of tumor progress in vivo by triggering apoptosis and cell cycle arrest associated with oxidative stress, suppression of HIF-1 and uncoupling of glycolytic metabolism. - Highlights: • Ascorbate potentiates the inhibition caused by juglone and Q7on tumor progress in vivo. • Juglone and Q7 with ascorbate caused widespread oxidative stress in tumor tissue. • Treatments inhibited HIF-1 and GLUT1 expression causing

  8. Effects of hydrogen fluoride and wounding on respiratory enzymes in soybean leaves

    Energy Technology Data Exchange (ETDEWEB)

    Lee, C J; Miller, G W; Welkie, G W

    1966-01-01

    Soybeans (Glycine max, merr, Var. Hawkeye) were cultured in Hoagland's solution and fumigated with hydrogen fluoride (ca. 100 ppb). After 24, 96 and 144 hr of fumigation, the enzyme activities of cytochrome oxidase, peroxidase, catalase, polyphenol oxidase, ascorbic acid oxidase and glucose-6-phosphate dehydrogenase were assayed in leaves from fumigated and control plants. The total oxygen uptake after each time of treatment was measured. The effect of mechanically wounding the tissue on the above enzymes was determined by rubbing with carborundum. Glucose-6-phosphate dehydrogenase activity from fumigated leaves showed an average increase of 5 to 22 times that of the control. Cytochrome oxidase, peroxidase and catalase activities were markedly stimulated by fluoride fumigation. Polyphenol oxidase activity was suppressed throughout the fumigation period. Ascorbic acid oxidase was stimulated at the initial state, then showed a steady decrease in activity. In vitro tests revealed that ascorbic acid oxidase and peroxidase were very sensitive to fluoride ions. Polyphenol oxidase was only slightly inhibited by 10/sup -2/M KF solution. Cytochrome oxidase and catalase were not affected by KF up to 10/sup -2/M. Total respiration throughout the treatment period showed an accelerated rate. All enzymes studied were stimulated by wounding. The effect of HF on respiration and specific enzymes is discussed in terms of direct effects and injury. 48 references, 8 tables.

  9. The biochemical, physiological and therapeutic roles of ascorbic acid

    African Journals Online (AJOL)

    STORAGESEVER

    2008-12-29

    Dec 29, 2008 ... is the loss of this single enzyme (the gene for the enzyme is defective) that ... several drugs in guinea pigs and even by sleep- deprivation and ..... metastatic state is linked to hydroxyl radical-induced DNA damage. Proc. Nat.

  10. Distribution and metabolism of ascorbic acid in pear fruits (Pyrus ...

    African Journals Online (AJOL)

    ajl user 1

    2013-04-17

    Apr 17, 2013 ... 2008), high light (Li et al., 2009), SO2 (Kubo et al., 1995) and wound- and .... Crude GalLDH enzyme extract was prepared using the method of ... Triton X-100, and 0.1 ml of the enzyme extract in 50 mM Tris-HCl. (pH 8.5), was ...

  11. Elevated Liver Enzymes

    Science.gov (United States)

    Symptoms Elevated liver enzymes By Mayo Clinic Staff Elevated liver enzymes may indicate inflammation or damage to cells in the liver. Inflamed or ... than normal amounts of certain chemicals, including liver enzymes, into the bloodstream, which can result in elevated ...

  12. Distribution of ascorbate-2-sulfate and distribution, half-life and turnover rates of [1-14C]ascorbic acid in rainbow trout

    International Nuclear Information System (INIS)

    Tucker, B.W.; Halver, J.E.

    1984-01-01

    Rainbow trout (250 g) were maintained at 15 degrees C for 3 months on a low ascorbic acid diet, given [1- 14 C]ascorbic acid by gavage, then fed the NAS/NRC requirement 12 times per week. Total urine, fecal water and branchial water were collected daily from five fish placed in metabolism chambers for four successive 5-day periods. Tissue samples were analyzed for 14 C, ascorbic acid (C1) and ascorbate-2-sulfate (C2). Excretion analysis indicated t1/2 . 42 days. After 20 days, the feeding schedule was changed to 3 times per week. Fish fed 14 C were sampled after 1, 2, 3 and 4 months. The half-life in each organ except brain was inversely proportional to the dietary level of ascorbate. Concentrations of C1 and C2 in the various tissues reflected dietary intake of vitamin C. Total C (CT . C1 + C2) levels were maintained in the liver even with the low vitamin C diet. Estimates of body pool for C1 are 27-29 mg/kg. At the higher ascorbate intake CT was 92-114 mg/kg, but decreased by 34% at the lower feeding rate to 51-62 mg/kg. Data indicate that there are two or more body pools that include a store of C2, which is readily interconverted in metabolizing tissues to and from C1. Since air and water stable C2 is antiscorbutic for fish, it is the preferred form of ascorbate for fish feeds

  13. Ligninolytic enzyme activities in mycelium of some wild and ...

    African Journals Online (AJOL)

    Lignin is probably one of the most recalcitrant compounds synthesized by plants. This compound is degraded by few microorganisms. White-rot fungi have been extensively studied due to its powerful ligninolytic enzymes. In this study, ligninolytic enzyme activities of different fungal species (six commercial and 13 wild) were ...

  14. Interactive effects of herbicide and enhanced UV-B on growth, oxidative damage and the ascorbate-glutathione cycle in two Azolla species.

    Science.gov (United States)

    Prasad, Sheo Mohan; Kumar, Sushil; Parihar, Parul; Singh, Rachana

    2016-11-01

    A field experiment was conducted to investigate the impact of alone and combined exposures of herbicide pretilachlor (5, 10 and 20μgml(-1)) and enhanced UV-B radiation (UV-B1; ambient +2.2kJm(-2) day(-1) and UV-B2; ambient +4.4kJm(-2) day(-1)) on growth, oxidative stress and the ascorbate-glutathione (AsA-GSH) cycle in two agronomically important Azolla spp. viz., Azolla microphylla and Azolla pinnata. Decreased relative growth rate (RGR) in both the species under tested stress could be linked to enhanced oxidative stress, thus higher H2O2 accumulation was observed, that in turn might have caused severe damage to lipids and proteins, thereby decreasing membrane stability. The effects were exacerbated when spp. were exposed to combined treatments of enhanced UV-B and pretilachlor. Detoxification of H2O2 is regulated by enzymes/metabolites of AsA-GSH cycle such as ascorbate peroxidase (APX) and glutathione reductase (GR) activity that were found to be stimulated. While, dehydroascorabte reductase (DHAR) activity, and the amount of metabolites: ascorbate (AsA), glutathione (GSH) and ratios of reduced/oxidized AsA (AsA/DHA) and GSH (GSH/GSSG), showed significant reduction with increasing doses of both the stressors, either applied alone or in combination. Glutathione-S-transferase (GST), an enzyme involved in scavenging of xenobiotics, was found to be stimulated under the tested stress. This study suggests that decline in DHAR activity and in AsA/DHA ratio might have led to enhanced H2O2 accumulation, thus decreased RGR was noticed under tested stress in both the species and the effect was more pronounced in A. pinnata. Owing to better performance of AsA-GSH cycle in A. microphylla, this study substantiates the view that A. microphylla is more tolerant than A. pinnata. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. Effects of ascorbic acid and antioxidants on color, lipid oxidation and volatiles of irradiated ground beef

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, D.U. E-mail: duahn@iastate.edu; Nam, K.C

    2004-10-01

    Beef loins with 3 different aging times after slaughter were ground, added with none, 0.1% ascorbic acid, 0.01% sesamol+0.01% {alpha}-tocopherol, or 0.1% ascorbic acid+0.01% sesamol+0.01% tocopherol. The meats were packaged in oxygen-permeable bags, irradiated at 2.5 kGy, and color, oxidation-reduction potential (ORP), lipid oxidation and volatile profiles were determined. Irradiation decreased the redness of ground beef, and visible color of beef changed from a bright red to a green/brown depending on the age of meat. Addition of ascorbic acid prevented color changes in irradiated beef, and the effect of ascorbic acid became greater as the age of meat or storage time after irradiation increased. The ground beef added with ascorbic acid had lower ORP than control, and the low ORP of meat helped maintaining the heme pigments in reduced form. During aerobic storage, S-volatiles disappeared while volatile aldehydes significantly increased in irradiated beef. Addition of ascorbic acid at 0.1% or sesamol+{alpha}-tocopherol at each 0.01% level to ground beef prior to irradiation were effective in reducing lipid oxidation and S-volatiles. As storage time increased, however, the antioxidant effect of sesamol+tocopherol in irradiated ground beef was superior to that of ascorbic acid.

  16. Effects of ascorbic acid and antioxidants on color, lipid oxidation and volatiles of irradiated ground beef

    International Nuclear Information System (INIS)

    Ahn, D.U.; Nam, K.C.

    2004-01-01

    Beef loins with 3 different aging times after slaughter were ground, added with none, 0.1% ascorbic acid, 0.01% sesamol+0.01% α-tocopherol, or 0.1% ascorbic acid+0.01% sesamol+0.01% tocopherol. The meats were packaged in oxygen-permeable bags, irradiated at 2.5 kGy, and color, oxidation-reduction potential (ORP), lipid oxidation and volatile profiles were determined. Irradiation decreased the redness of ground beef, and visible color of beef changed from a bright red to a green/brown depending on the age of meat. Addition of ascorbic acid prevented color changes in irradiated beef, and the effect of ascorbic acid became greater as the age of meat or storage time after irradiation increased. The ground beef added with ascorbic acid had lower ORP than control, and the low ORP of meat helped maintaining the heme pigments in reduced form. During aerobic storage, S-volatiles disappeared while volatile aldehydes significantly increased in irradiated beef. Addition of ascorbic acid at 0.1% or sesamol+α-tocopherol at each 0.01% level to ground beef prior to irradiation were effective in reducing lipid oxidation and S-volatiles. As storage time increased, however, the antioxidant effect of sesamol+tocopherol in irradiated ground beef was superior to that of ascorbic acid

  17. Role of ascorbic acid in stratum corneum lipid models exposed to UV irradiation.

    Science.gov (United States)

    Trommer, Hagen; Böttcher, Roif; Pöppl, Andreas; Hoentsch, Joachim; Wartewig, Siegfried; Neubert, Reinhard H H

    2002-07-01

    The effects of ascorbic acid on Stratum corneum lipid models following ultraviolet irradiation were studied adding iron ions as transition metal catalysts. Lipid peroxidation was quantified by the thiobarbituric acid assay. The qualitative changes were studied on a molecular level by mass spectrometry. To elucidate the nature of free radical involvement we carried out electron paramagnetic resonance studies. The influence of ascorbic acid on the concentration of hydroxyl radicals was examined using the spin trapping technique. Moreover, we checked the vitamin's ability to react with stable radicals. Ascorbic acid was found to have prooxidative effects in all lipid systems in a concentration dependent manner. The degradation products of ascorbic acid after its prooxidative action were detected. The concentration of the hydroxyl radicals in the Fenton assay was decreased by ascorbic acid. The quantification assay of 2,2-diphenyl-1-picrylhydrazyl hydrate showed reduced concentration levels of the stable radical caused by ascorbic acid. Considering human skin and its constant exposure to UV light and oxygen, an increased pool of iron ions in irradiated skin and the depletion of co-antioxidants, the administration of ascorbic acid in cosmetic formulations or in sunscreens could unfold adverse effects among the Stratum corneum lipids.

  18. High Dose Ascorbate Causes Both Genotoxic and Metabolic Stress in Glioma Cells

    Science.gov (United States)

    Castro, Maria Leticia; Carson, Georgia M.; McConnell, Melanie J.; Herst, Patries M.

    2017-01-01

    We have previously shown that exposure to high dose ascorbate causes double stranded breaks (DSBs) and a build-up in S-phase in glioblastoma (GBM) cell lines. Here we investigated whether or not this was due to genotoxic stress as well as metabolic stress generated by exposure to high dose ascorbate, radiation, ascorbate plus radiation and H2O2 in established and primary GBM cell lines. Genotoxic stress was measured as phosphorylation of the variant histone protein, H2AX, 8-oxo-7,8-dihydroguanine (8OH-dG) positive cells and cells with comet tails. Metabolic stress was measured as a decrease in NADH flux, mitochondrial membrane potential (by CMXRos), ATP levels (by ATP luminescence) and mitochondrial superoxide production (by mitoSOX). High dose ascorbate, ascorbate plus radiation, and H2O2 treatments induced both genotoxic and metabolic stress. Exposure to high dose ascorbate blocked DNA synthesis in both DNA damaged and undamaged cell of ascorbate sensitive GBM cell lines. H2O2 treatment blocked DNA synthesis in all cell lines with and without DNA damage. DNA synthesis arrest in cells with damaged DNA is likely due to both genotoxic and metabolic stress. However, arrest in DNA synthesis in cells with undamaged DNA is likely due to oxidative damage to components of the mitochondrial energy metabolism pathway. PMID:28737676

  19. Progress of Mimetic Enzymes and Their Applications in Chemical Sensors.

    Science.gov (United States)

    Yang, Bin; Li, Jianping; Deng, Huan; Zhang, Lianming

    2016-11-01

    The need to develop innovative and reformative approaches to synthesize chemical sensors has increased in recent years because of demands for selectivity, stability, and reproducibility. Mimetic enzymes provide an efficient and convenient method for chemical sensors. This review summarizes the application of mimetic enzymes in chemical sensors. Mimetic enzymes can be classified into five categories: hydrolases, oxidoreductases, transferases, isomerases, and induced enzymes. Potential and recent applications of mimetic enzymes in chemical sensors are reviewed in detail, and the outlook of profound development has been illustrated.

  20. Facile synthesis of graphene hybrid tube-like structure for simultaneous detection of ascorbic acid, dopamine, uric acid and tryptophan

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Wen [Education Ministry Key Laboratory on Luminescence and Real-Time Analysis, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Chai Yaqin, E-mail: yqchai@swu.edu.cn [Education Ministry Key Laboratory on Luminescence and Real-Time Analysis, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Yuan Ruo, E-mail: yuanruo@swu.edu.cn [Education Ministry Key Laboratory on Luminescence and Real-Time Analysis, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Chen Shihong; Han Jing; Yuan Dehua [Education Ministry Key Laboratory on Luminescence and Real-Time Analysis, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China)

    2012-12-05

    Graphical abstract: A tube-like structure of graphene hybrid (GS-PTCA) was synthesized via {pi}-{pi} stacking interaction, and was used as modifier to fabricate electrode for simultaneous detection of ascorbic acid (AA), dopamine (DA), uric acid (UA) and tryptophan (Trp). SEM images of GS, PTCA and GS-PTCA were presented. Under the synergistic effects between GS and PTCA, the modified electrode displayed high catalytic activity and selectivity toward the oxidation of AA, DA, UA, and Trp. Highlights: Black-Right-Pointing-Pointer A simple strategy for simultaneous detection of AA, DA, UA and Trp has been constructed. Black-Right-Pointing-Pointer The tube-like structure of graphene hybrid (GS-PTCA) was synthesized. Black-Right-Pointing-Pointer The GS-PTCA provided a selective interface for discrimination of AA, DA, UA and Trp. - Abstract: In the present work, a tube-like structure of graphene hybrid as modifier to fabricate electrode for simultaneous detection of ascorbic acid (AA), dopamine (DA), uric acid (UA) and tryptophan (Trp) was reported. The hybrid was synthesized by a simple method based on graphene sheets (GS) and 3,4,9,10-perylenetetracarboxylic acid (PTCA) via {pi}-{pi} stacking interaction under ultrasonic condition. The combination of GS and PTCA could effectively improve the dispersion of GS, owing to PTCA with the carboxylic-functionalized interface. Comparing with pure GS or PTCA modified electrode, GS-PTCA displayed high catalytic activity and selectivity toward the oxidation of AA, DA, UA, and Trp. Moreover, cyclic voltammetry, different pulse voltammetry and scanning electron microscopy were employed to characterize the sensors. The experiment results showed that the linear response range for simultaneous detection of AA, DA, UA, and Trp were 20-420 {mu}M, 0.40-374 {mu}M, 4-544 {mu}M and 0.40-138 {mu}M, respectively, and the detection limits were 5.60 {mu}M, 0.13 {mu}M, 0.92 {mu}M and 0.06 {mu}M (S/N = 3). Importantly, the proposed method offers

  1. Structural Requirements of Alkylglyceryl-l-Ascorbic Acid Derivatives for Melanogenesis Inhibitory Activity.

    Science.gov (United States)

    Taira, Norihisa; Katsuyama, Yushi; Yoshioka, Masato; Muraoka, Osamu; Morikawa, Toshio

    2018-04-10

    l-Ascorbic acid has multifunctional benefits on skin aesthetics, including inhibition of melanin production, and is widely used in cosmetics. It, however, has low stability and poor skin penetration. We hypothesize that alkylglyceryl-l-ascorbic acid derivatives, highly stable vitamin C-alkylglycerol conjugates, would have similar anti-melanogenic activity with better stability and penetration. We test 28 alkylglyceryl-l-ascorbic acid derivatives ( 1 - 28 ) on theophylline-stimulated B16 melanoma 4A5 cells to determine if they inhibit melanogenesis and establish any structure-function relationships. Although not the most potent inhibitors, 3- O -(2,3-dihydroxypropyl)-2- O -hexyl-l-ascorbic acid ( 6 , IC 50 = 81.4 µM) and 2- O -(2,3-dihydroxypropyl)-3- O -hexyl-l-ascorbic acid ( 20 , IC 50 = 117 µM) are deemed the best candidate derivatives based on their inhibitory activities and low toxicities. These derivatives are also found to be more stable than l-ascorbic acid and to have favorable characteristics for skin penetration. The following structural requirements for inhibitory activity of alkylglyceryl-l-ascorbic acid derivatives are also determined: (i) alkylation of glyceryl-l-ascorbic acid is essential for inhibitory activity; (ii) the 3- O -alkyl-derivatives ( 2 - 14 ) exhibit stronger inhibitory activity than the corresponding 2- O -alkyl-derivatives ( 16 - 28 ); and (iii) derivatives with longer alkyl chains have stronger inhibitory activities. Mechanistically, our studies suggest that l-ascorbic acid derivatives exert their effects by suppressing the mRNA expression of tyrosinase and tyrosine-related protein-1.

  2. Enzymes of industrial purpose - review of the market of enzyme preparations and prospects for its development

    Directory of Open Access Journals (Sweden)

    A. A. Tolkacheva

    2017-01-01

    Full Text Available Microbial enzyme preparations are increasingly replacing conventional chemical catalysts in a number of industrial processes. Such drugs, in addition to environmental friendliness and high activity, have a number of advantages over enzyme preparations of vegetable and animal origin, namely: the production of microbial enzymes in bioreactors is easily controlled and predictable; excreted microbiological enzymes are more stable than intracellular animals and plant enzymes; the genetic diversity of microorganisms makes it possible to produce enzyme preparations with a wide range of specificity; microbiological enzymes can be synthesized year-round, in contrast to the production of plant enzymes, which is often seasonal. The leaders of the world market of enzymes are proteases and amylases, which account for 25% and 15%, respectively. Over the past five years, the world market for carbohydrases, including mainly amylases, cellulases and xylanases, has been the fastest growing segment of the enzyme market with an aggregate annual growth rate of more than 7.0%. Another major product of the industrial enzyme market, which has a great potential for growth, is lipases. From the point of view of designation, the main part is represented by food and food enzymes. The Russian market continues to be unsaturated - the current supply is not able to meet the needs of the Russian feed and food industry in enzyme preparations. Enzyme preparations of domestic producers are in demand in forage production, while food industrial enterprises prefer imported products. The most significant enterprises in the enzymatic industry in Russia at the moment are Sibbiofarm, AgroSistema, Agroferment. In the light of the Russian policy of increasing food security, the development of the domestic enzyme industry is an extremely topical task.

  3. Efficient and rapid microwave-assisted route to synthesize Pt–MnOx hydrogen peroxide sensor

    International Nuclear Information System (INIS)

    Kivrak, Hilal; Alal, Orhan; Atbas, Dilan

    2015-01-01

    Highlights: • Carbon supported Pt-MnOx catalyst could be synthesized succesfully by microwave irradiation method. • Carbon supported Pt-MnOx non-enzymatic H 2 O 2 sensor exhibits excellent selectivity, stability, and reproducibility • Carbon supported Pt-MnOx sensor can effectively resist the effect of interferents such as uric acid and ascorbic acid. - Abstract: A novel electrochemical sensor for the detection of hydrogen peroxide (H 2 O 2 ) is proposed based on carbon supported Pt-MnO x and Pt nanoparticles, successfully synthesized via microwave irradiation polyol method. The physicochemical properties of the Pt-MnO x and Pt nanoparticles were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Transmission electron microscopy (TEM). Electrochemical properties of the nanoparticles were investigated by cyclic voltammetry (CV) and chronoamperometry (CA). Electrochemical measurements indicate that the oxidation current of H 2 O 2 is linear (R 2 =0.998) to its concentration from 2 μM to 4.0 mM with a detection limit of 0.7 μM (signal/noise = 3). In addition, Pt-MnO x is not affected by ascorbic acid (AA) and uric acid (UA) which are common interfering species. Meanwhile, this Pt-MnO x non-enzymatic H 2 O 2 sensor exhibits excellent selectivity, stability and reproducibility. Thus, this novel non-enzymatic sensor can be found practical applications in H 2 O 2 detection

  4. Graphitic carbon nitride nanosheets doped graphene oxide for electrochemical simultaneous determination of ascorbic acid, dopamine and uric acid

    International Nuclear Information System (INIS)

    Zhang, Hanqiang; Huang, Qitong; Huang, Yihong; Li, Feiming; Zhang, Wuxiang; Wei, Chan; Chen, Jianhua; Dai, Pingwang; Huang, Lizhang; Huang, Zhouyi; Kang, Lianping; Hu, Shirong; Hao, Aiyou

    2014-01-01

    Graphical abstract: Schematic drawing of electrochemical oxidize AA, DA and UA on graphitic carbon nitride nanosheets-graphene oxide composite modified electrode. - Highlights: • Synthesize g-C 3 N 4 , GO and CNNS-GO composite. • CNNS-GO composite was the first time for simultaneous determination of AA, DA and UA. • CNNS-GO/GCE displays fantastic selectivity and sensitivity for AA, DA and UA. • CNNS-GO/GCE was applied to detect real sample with satisfactory results. - Abstract: Graphitic carbon nitride nanosheets with a graphite-like structure have strong covalent bonds between carbon and nitride atoms, and nitrogen atoms in the carbon architecture can accelerate the electron transfer and enhance electrical properties effectually. The graphitic carbon nitride nanosheets-graphene oxide composite was synthesized. And the electrochemical performance of the composite was investigated by cyclic voltammetry and differential pulse voltammetry ulteriorly. Due to the synergistic effects of layer-by-layer structures by π-π stacking or charge-transfer interactions, graphitic carbon nitride nanosheets-graphene oxide composite can improved conductivity, electro-catalytic and selective oxidation performance. The proposed graphitic carbon nitride nanosheets-graphene oxide composite modified electrode was employed for simultaneous determination of ascorbic acid, dopamine and uric acid in their mixture solution, it exhibited distinguished sensitivity, wide linear range and low detection limit. Moreover, the modified electrode was applied to detect urine and dopamine injection sample, and then the samples were spiked with certain concentration of three substances with satisfactory recovery results

  5. Redox regulation of peroxiredoxin and proteinases by ascorbate and thiols during pea root nodule senescence.

    Science.gov (United States)

    Groten, Karin; Dutilleul, Christelle; van Heerden, Philippus D R; Vanacker, Hélène; Bernard, Stéphanie; Finkemeier, Iris; Dietz, Karl-Josef; Foyer, Christine H

    2006-02-20

    Redox factors contributing to nodule senescence were studied in pea. The abundance of the nodule cytosolic peroxiredoxin but not the mitochondrial peroxiredoxin protein was modulated by ascorbate. In contrast to redox-active antioxidants such as ascorbate and cytosolic peroxiredoxin that decreased during nodule development, maximal extractable nodule proteinase activity increased progressively as the nodules aged. Cathepsin-like activities were constant throughout development but serine and cysteine proteinase activities increased during senescence. Senescence-induced cysteine proteinase activity was inhibited by cysteine, dithiotreitol, or E-64. Senescence-dependent decreases in redox-active factors, particularly ascorbate and peroxiredoxin favour decreased redox-mediated inactivation of cysteine proteinases.

  6. Effect of residual ascorbate on determination of nitrite in commercial cured meat products.

    Science.gov (United States)

    Fox, J B; Doerr, R C; Gates, R

    1984-01-01

    Residual ascorbate in cured meat slurries results in different amounts of pigment being produced from different Griess reagent combinations. The phenomenon was used to study residual ascorbate in commercial cured meat products which had a variety of textures, acidities, moisture and meat content, fat, homogeneity, initial nitrite, and processing conditions. Diluting and heating the samples according to the AOAC procedure did not completely eliminate the ascorbate interference, but making the sample alkaline did. Determining nitrite separately in supernate and precipitate from the first dilution showed the effect of heating to be the elimination of interferences and solubilization or extraction of nitrite from the precipitate.

  7. Metabolic Conversion of l-Ascorbic Acid to Oxalic Acid in Oxalate-accumulating Plants 1

    Science.gov (United States)

    Yang, Joan C.; Loewus, Frank A.

    1975-01-01

    l-Ascorbic acid-1-14C and its oxidation product, dehydro-l-ascorbic acid, produced labeled oxalic acid in oxalate-accumulating plants such as spinach seedlings (Spinacia oleracea) and the detached leaves of woodsorrel (Oxalis stricta and O. oregana), shamrock (Oxalis adenopylla), and begonia (Begonia evansiana). In O. oregana, conversion occurred equally well in the presence or absence of light. This relationship between l-ascorbic acid metabolism and oxalic acid formation must be given careful consideration in attempts to explain oxalic accumulation in plants. PMID:16659288

  8. Salivary ascorbic acid levels in betel quid chewers: A biochemical study

    OpenAIRE

    Shetty, Shishir R.; Babu, Subhas; Kumari, Suchetha; Prasad, Rajendra; Bhat, Supriya; Fazil, K. A.

    2013-01-01

    Background: Quid chewing practice has been a part of our tradition since centuries with little known evidence of oral cancer. However, recent trends show a rise in occurrence of oral cancer often associated with tobacco and arecanut usage. Ascorbic acid is an important salivary antioxidant. Betel leaf which is used in quid is known to contain ascorbic acid. Aim: The aim of our study was to assess the salivary levels of ascorbic acid in traditional quid chewers so as to determine whether the b...

  9. The effects of ascorbic acid on diphtheria toxin and intoxicated hela cells

    International Nuclear Information System (INIS)

    Clark, C.E.; Smith, T.J.

    1976-01-01

    Ascorbic acid (vitamin C) prevented diphtheria toxin from inhibiting the incorporation of [U- 14 C]-alanine into trichloroacetic acid precipitable material in HeLa cells. Ascorbic acid did not exhibit an effect on the adenosine diphosphate-ribosylation of amino acyl transferase 2 nor did it separate fragment A from fragment B in ''nicked'' toxin. A non-specific reducing agent, para-methylaminophenol sulfate, exhibited an effect of HeLa cells very similar to the results of ascorbic acid. Citric acid, a tricarboxylic acid, had no effect on HeLa cells. (auth.)

  10. Indirect potentiometric titration of ascorbic acid in pharmaceutical preparations using copper based mercury film electrode.

    Science.gov (United States)

    Abdul Kamal Nazer, Meeran Mohideen; Hameed, Abdul Rahman Shahul; Riyazuddin, Patel

    2004-01-01

    A simple and rapid potentiometric method for the estimation of ascorbic acid in pharmaceutical dosage forms has been developed. The method is based on treating ascorbic acid with iodine and titration of the iodide produced equivalent to ascorbic acid with silver nitrate using Copper Based Mercury Film Electrode (CBMFE) as an indicator electrode. Interference study was carried to check possible interference of usual excipients and other vitamins. The precision and accuracy of the method was assessed by the application of lack-of-fit test and other statistical methods. The results of the proposed method and British Pharmacopoeia method were compared using F and t-statistical tests of significance.

  11. Information Retrieval for Ecological Syntheses

    Science.gov (United States)

    Bayliss, Helen R.; Beyer, Fiona R.

    2015-01-01

    Research syntheses are increasingly being conducted within the fields of ecology and environmental management. Information retrieval is crucial in any synthesis in identifying data for inclusion whilst potentially reducing biases in the dataset gathered, yet the nature of ecological information provides several challenges when compared with…

  12. Method of synthesizing pyrite nanocrystals

    Science.gov (United States)

    Wadia, Cyrus; Wu, Yue

    2013-04-23

    A method of synthesizing pyrite nanocrystals is disclosed which in one embodiment includes forming a solution of iron (III) diethyl dithiophosphate and tetra-alkyl-ammonium halide in water. The solution is heated under pressure. Pyrite nanocrystal particles are then recovered from the solution.

  13. A highly sensitive electrochemical biosensor for catechol using conducting polymer reduced graphene oxide-metal oxide enzyme modified electrode.

    Science.gov (United States)

    Sethuraman, V; Muthuraja, P; Anandha Raj, J; Manisankar, P

    2016-10-15

    The fabrication, characterization and analytical performances were investigated for a catechol biosensor, based on the PEDOT-rGO-Fe2O3-PPO composite modified glassy carbon (GC) electrode. The graphene oxide (GO) doped conducting polymer poly (3,4-ethylenedioxythiophene) (PEDOT) was prepared through electrochemical polymerization by potential cycling. Reduction of PEDOT-GO was carried out by amperometric method. Fe2O3 nanoparticles were synthesized in ethanol by hydrothermal method. The mixture of Fe2O3, PPO and glutaraldehyde was casted on the PEDOT-rGO electrode. The surface morphology of the modified electrodes was studied by FE-SEM and AFM. Cyclic voltammetric studies of catechol on the enzyme modified electrode revealed higher reduction peak current. Determination of catechol was carried out successfully by Differential Pulse Voltammetry (DPV) technique. The fabricated biosensor investigated shows a maximum current response at pH 6.5. The catechol biosensor exhibited wide sensing linear range from 4×10(-8) to 6.20×10(-5)M, lower detection limit of 7×10(-9)M, current maxima (Imax) of 92.55µA and Michaelis-Menten (Km) constant of 30.48µM. The activation energy (Ea) of enzyme electrode is 35.93KJmol(-1) at 50°C. There is no interference from d-glucose and l-glutamic acid, ascorbic acid and o-nitrophenol. The PEDOT-rGO-Fe2O3-PPO biosensor was stable for at least 75 days when stored in a buffer at about 4°C. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Ascorbic acid transported by sodium-dependent vitamin C transporter 2 stimulates steroidogenesis in human choriocarcinoma cells.

    Science.gov (United States)

    Wu, Ximei; Iguchi, Takuma; Itoh, Norio; Okamoto, Kousuke; Takagi, Tatsuya; Tanaka, Keiichi; Nakanishi, Tsuyoshi

    2008-01-01

    Reduced vitamin C [ascorbic acid (AA)], which is taken up into cells by sodium-dependent vitamin C transporter (SVCT) 1 and 2, is believed to be important for hormone synthesis, but its role in generating placental steroids needed to maintain pregnancy and fetal development is not clear. To determine the steroidogenic effect of AA and the role of SVCT2 in AA-induced steroidogenesis, we tested the effects of AA treatment and SVCT2 knockdown on steroidogenesis in human choriocarcinoma cell lines. AA treatment of JEG-3, BeWo, and JAR cells for 48-h dose dependently increased progesterone and estradiol levels. In JEG-3 cells, AA increased the mRNA expression of P450 cholesterol side-chain cleavage enzyme, 3beta-hydroxysteroid dehydrogenase type 1, and aromatase, key enzymes for steroidogenesis. Stable knockdown of SVCT2 in JEG-3 cells by retrovirally mediated RNA interference decreased the maximal velocity of AA uptake by approximately 50%, but apparent affinity values were not affected. SVCT2 knockdown in JEG-3 cells significantly suppressed the AA-induced mRNA expression of placental P450 cholesterol side-chain cleavage enzyme, 3beta-hydroxysteroid dehydrogenase type 1, and aromatase. This suppression of the AA-induced mRNA expression of steroidogenic enzymes subsequently decreased progesterone and estradiol production. In addition, inhibition of MAPK kinase-ERK signaling, which is a major pathway for AA-regulated gene expression, failed to affect AA-induced steroidogenesis. Our observations indicate that SVCT2-mediated AA uptake into cells is necessary for AA-induced steroidogenesis in human choriocarcinoma cell, but MAPK kinase-ERK signaling is not involved in AA-induced steroidogenesis.

  15. Cotton Ascorbate Oxidase Promotes Cell Growth in Cultured Tobacco Bright Yellow-2 Cells through Generation of Apoplast Oxidation

    Science.gov (United States)

    Li, Rong; Xin, Shan; Tao, Chengcheng; Jin, Xiang; Li, Hongbin

    2017-01-01

    Ascorbate oxidase (AO) plays an important role in cell growth through the modulation of reduction/oxidation (redox) control of the apoplast. Here, a cotton (Gossypium hirsutum) apoplastic ascorbate oxidase gene (GhAO1) was obtained from fast elongating fiber tissues. GhAO1 belongs to the multicopper oxidase (MCO) family and includes a signal peptide and several transmembrane regions. Analyses of quantitative real-time polymerase chain reaction (QRT-PCR) and enzyme activity showed that GhAO1 was expressed abundantly in 15-day post-anthesis (dpa) wild-type (WT) fibers in comparison with fuzzless-lintless (fl) mutant ovules. Subcellular distribution analysis in onion cells demonstrated that GhAO1 is localized in the cell wall. In transgenic tobacco bright yellow-2 (BY-2) cells with ectopic overexpression of GhAO1, the enhancement of cell growth with 1.52-fold increase in length versus controls was indicated, as well as the enrichment of both total ascorbate in whole-cells and dehydroascorbate acid (DHA) in apoplasts. In addition, promoted activities of AO and monodehydroascorbate reductase (MDAR) in apoplasts and dehydroascorbate reductase (DHAR) in whole-cells were displayed in transgenic tobacco BY-2 cells. Accumulation of H2O2, and influenced expressions of Ca2+ channel genes with the activation of NtMPK9 and NtCPK5 and the suppression of NtTPC1B were also demonstrated in transgenic tobacco BY-2 cells. Finally, significant induced expression of the tobacco NtAO gene in WT BY-2 cells under indole-3-acetic acid (IAA) treatment appeared; however, the sensitivity of the NtAO gene expression to IAA disappeared in transgenic BY-2 cells, revealing that the regulated expression of the AO gene is under the control of IAA. Taken together, these results provide evidence that GhAO1 plays an important role in fiber cell elongation and may promote cell growth by generating the oxidation of apoplasts, via the auxin-mediated signaling pathway. PMID:28644407

  16. On the protection of E.coli against radiation lethality by ascorbate combined with tetracycline

    International Nuclear Information System (INIS)

    Djalali-Behzad, G.; Ehrenberg, L.

    1977-01-01

    The radioprotective action in E.coli ATCC 9637 of ascorbate added to media containing the weak sensitizer, tetracycline (Pittillo, R.F., and Lucas, M.B., 1967, Radiat. Res., vol. 31, 36) was found to be dependent on the presence of metal catalysts of the autoxidation of ascorbate. Thus, the protective action of ascorbate + tetracycline as well as the rate of autoxidation of ascorbate in this mixture were enhanced by 0.1 μM Cu, and these effects were counteracted by pyrophosphate probably through chelation of iron that contaminates phosphate. A suppression of metabolism is apparently involved in the combined action as judged by the decrease of incorporation of labelled uridine. (author)

  17. Enthalpic characteristics of interactions occurring between an ascorbic acid and some saccharides in aqueous solutions

    International Nuclear Information System (INIS)

    Terekhova, Irina V.; Kulikov, Oleg V.; Titova, Elena S.

    2004-01-01

    The enthalpies of solution of mono- and disaccharides were measured in water and aqueous ascorbic acid solutions at 298.15 K using a calorimeter of solution. Enthalpies of transfer of saccharides from water to aqueous ascorbic acid solutions were derived, and enthalpic coefficients of pair interaction h xy were calculated according to MacMillan-Mayer theory. Interactions of ascorbic acid with D-fructose and sucrose are energetically favorable and characterized by negative h xy coefficients while h xy for the interactions occurring between ascorbic acid and α-D glucose, D-galactose and maltose are positive. The obtained results are interpreted in terms of the influence of structure and solvation of solutes on the thermodynamic parameters of their interaction in solutions

  18. Effect of Combined Intake of Garcinia Kola and Ascorbic Acid on ...

    African Journals Online (AJOL)

    Proximate and nutritional composition of kola nut, garcinia kola and alligator pepper. African Journal ... primarily carried bound to albumin in the blood and only a minor amount is ... increased oxida ve stress. With regular intake, the ascorbic ...

  19. Study of Ascorbic Acid as Iron(III Reducing Agent for Spectrophotometric Iron Speciation

    Directory of Open Access Journals (Sweden)

    Antesar Elmagirbi

    2012-10-01

    Full Text Available The study of ascorbic acid as a reducing agent for iron(III has been investigated in order to obtain an alternative carcinogenic reducing agent, hydroxylamine, used in spectrophotometric standard method based on the formation of a red-orange complex of Fe(II-o-phenanthroline. The study was optimised with regards to ascorbic acid concentration as well as pH solution. The results showed that ascorbic acid showed maximum capacity as reducing agent of iron(III under concentration of 4.46.10-4 M and pH solution of 1-4.Under these conditions, ascorbic acid reduced iron(III proportionally and performed similarly to that of hydroxylamine.  The method gave result to linear calibration over the range of 0.2-2 mg/L withhigh accuracy of 97 % and relative standard deviation of less than 2 %. This method was successfully applied to assay iron speciation in water samples.

  20. Ascorbic acid effects on in vitro maturation of mouse oocyte with or ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-10-19

    Oct 19, 2009 ... in origin, that function interactively and synergistically to neutralize free radicals. ... antioxidant properties of ascorbic acid enable it to protect tissues from reactive oxygen ..... Effect of cyclic AMP on the isolated oocytecumulus ...

  1. Effect of sodium ascorbate and delayed treatment on the shear bond ...

    African Journals Online (AJOL)

    Background: The effect of bleaching on enamel surfaces, as well as exploring methods of preventing the weakening ..... the calcium, phosphorus, sulfur and potassium content of ... demonstrated the potential protective effect of ascorbic.

  2. Protection of E. coli against radiation lethality by ascorbate combined with tetracycline

    Energy Technology Data Exchange (ETDEWEB)

    Djalali-Behzad, G; Ehrenberg, L [Stockholm Univ. (Sweden). Radiobiologiska Institutionen

    1977-06-01

    The radioprotective action in E.coli ATCC 9637 of ascorbate added to media containing the weak sensitizer, tetracycline (Pittillo, R.F., and Lucas, M.B., 1967, Radiat. Res., vol. 31, 36) was found to be dependent on the presence of metal catalysts of the autoxidation of ascorbate. Thus, the protective action of ascorbate + tetracycline as well as the rate of autoxidation of ascorbate in this mixture were enhanced by 0.1 ..mu..M Cu, and these effects were counteracted by pyrophosphate probably through chelation of iron that contaminates phosphate. A suppression of metabolism is apparently involved in the combined action as judged by the decrease of incorporation of labelled uridine.

  3. Plant growth regulators and ascorbic acid effects on physiological quality of wheat seedlings obtained from deteriorated seeds

    International Nuclear Information System (INIS)

    Moori, S.; Eisv, H.R.

    2017-01-01

    This study attempted to examine the effect of seed priming using plant growth regulators and vitamin C on the physiological traits of non-aged and aged seeds of wheat and their obtained seedlings. Accelerated aging (AA) method (40 degree C, RH=100% for 72h) was used for aging seeds. The seeds were pre-treated by gibberellin (GA), salicylic acid (SA), brassinosteroid (BR), and ascorbic acid (AS). Some seed traits such as germination and electric conductivity (EC) and seedling traits such as malondialdehyde (MDA) content, activity of some antioxidant enzymes, soluble protein content (SP), soluble sugar (SS), and proline were measured seven days after germination. The results showed that accelerated aging of seeds reduces the germination percentage and speed, increases soluble sugar, and reduces soluble protein, activity of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) in the seedling. Pre-treatment of the aged seed by GA had the maximum positive impact on seed germination and seedling growth. Priming improved germination indices, quality of seedling, and seedling resistance against the oxidative stress caused by AA. It also improved cell membrane integrity and thus reduced seeds’ EC. Priming increased the activity of CAT, POD and SOD enzymes in both aged and non-aged seeds. When the deteriorated seeds were primed, proline and SS contents of the seedling increased significantly, but SP and MDA decreased. In general, pre-treatment of the non-aged and aged seeds by gibberellin improved the physiological quality of the seed and seedling. (author)

  4. Ascorbic Acid Alleviates Water Stress in Young Peach Trees and Improves Their Performance after Rewatering

    Directory of Open Access Journals (Sweden)

    Consuelo Penella

    2017-09-01

    Full Text Available Exogenous application of biochemicals has been found to improve water stress tolerance in herbaceous crops but there are limited studies on deciduous fruit trees. The goal of this research was to study if ascorbic acid applications could improve physiological mechanisms associated with water stress tolerance in young fruit trees. Ascorbic acid was foliarly applied at a concentration of 250 ppm to water-stressed and well-watered peach trees (control of two cultivars (‘Scarletprince’ and ‘CaroTiger’. Trees received either one or two applications, and 1 week after the second application all trees were rewatered to field capacity. Upon rewatering, CO2 assimilation and stomatal conductance of water-stressed ‘Scarletprince’ trees sprayed with ascorbic acid (one or two applications were similar to those of well-irrigated trees, but water-stressed trees that had not received ascorbic acid did not recover photosynthetical functions. Also, water status in sprayed water-stressed ‘Scarletprince’ trees was improved to values similar to control trees. On the other hand, water-stressed ‘CaroTiger’ trees needed two applications of ascorbic acid to reach values of CO2 assimilation similar to control trees but these applications did not improve their water status. In general terms, different response mechanisms to cope with water stress in presence of ascorbic acid were found in each cultivar, with ‘Scarletprince’ trees preferentially using proline as compatible solute and ‘CaroTiger’ trees relying on stomatal regulation. The application of ascorbic acid reduced cell membrane damage and increased catalase activity in water-stressed trees of both cultivars. These results suggest that foliar applications of ascorbic acid could be used as a management practice for improving water stress tolerance of young trees under suboptimal water regimes.

  5. Ascorbic Acid Alleviates Water Stress in Young Peach Trees and Improves Their Performance after Rewatering.

    Science.gov (United States)

    Penella, Consuelo; Calatayud, Ángeles; Melgar, Juan C

    2017-01-01

    Exogenous application of biochemicals has been found to improve water stress tolerance in herbaceous crops but there are limited studies on deciduous fruit trees. The goal of this research was to study if ascorbic acid applications could improve physiological mechanisms associated with water stress tolerance in young fruit trees. Ascorbic acid was foliarly applied at a concentration of 250 ppm to water-stressed and well-watered peach trees (control) of two cultivars ('Scarletprince' and 'CaroTiger'). Trees received either one or two applications, and 1 week after the second application all trees were rewatered to field capacity. Upon rewatering, CO 2 assimilation and stomatal conductance of water-stressed 'Scarletprince' trees sprayed with ascorbic acid (one or two applications) were similar to those of well-irrigated trees, but water-stressed trees that had not received ascorbic acid did not recover photosynthetical functions. Also, water status in sprayed water-stressed 'Scarletprince' trees was improved to values similar to control trees. On the other hand, water-stressed 'CaroTiger' trees needed two applications of ascorbic acid to reach values of CO 2 assimilation similar to control trees but these applications did not improve their water status. In general terms, different response mechanisms to cope with water stress in presence of ascorbic acid were found in each cultivar, with 'Scarletprince' trees preferentially using proline as compatible solute and 'CaroTiger' trees relying on stomatal regulation. The application of ascorbic acid reduced cell membrane damage and increased catalase activity in water-stressed trees of both cultivars. These results suggest that foliar applications of ascorbic acid could be used as a management practice for improving water stress tolerance of young trees under suboptimal water regimes.

  6. Hemato-biochemical responses to packing in donkeys administered ascorbic acid during the harmattan season

    OpenAIRE

    OLAIFA, Folashade; AYO, Joseph Olusegun; AMBALI, Suleiman Folorunsho; REKWOT, Peter Ibrahim

    2012-01-01

    Experiments were performed to investigate the effect of ascorbic acid (AA) in reducing hemato-biochemical changes in pack donkeys during the cold-dry (harmattan) season. Six experimental donkeys administered orally AA (200 mg/kg) and six control donkeys not administered ascorbic acid were subjected to packing. Blood samples were collected from all donkeys for hematological and biochemical analyses. In the control donkeys, packed cell volume (PCV), erythrocyte count and hemoglobin concentratio...

  7. Over-expression of ascorbate oxidase in the apoplast of transgenic tobacco results in altered ascorbate and glutathione redox states and increased sensitivity to ozone

    DEFF Research Database (Denmark)

    Sanmartin, Maite; Drogoudi, Pavlina D.; Lyons, Tom

    2003-01-01

    overexpressing plants exposed to 100 nmol mol-1 ozone for 7 h day-1 exhibited a substantial increase in foliar injury, and a greater pollutant-induced reduction in both the light-saturated rate of CO2 assimilation and the maximum in vivo rate of ribulose-1,5-bisphosphate carboxylase/oxygenase carboxylation......Transgenic tobacco (Nicotiana tabacum L. cv. Xanthi) plants expressing cucumber ascorbate oxidase (EC.1.10.3.3) were used to examine the role of extracellular ascorbic acid in mediating tolerance to the ubiquitous air pollutant, ozone (O3). Three homozygous transgenic lines, chosen on the basis...

  8. Solid phase syntheses of oligoureas

    Energy Technology Data Exchange (ETDEWEB)

    Burgess, K.; Linthicum, D.S.; Russell, D.H.; Shin, H.; Shitangkoon, A.; Totani, R.; Zhang, A.J.; Ibarzo, J. [Texas A& M Univ., College Station, TX (United States)

    1997-02-19

    Isocyanates 7 were formed from monoprotected diamines 3 or 6, which in turn can be easily prepared from commercially available N-BOC- or N-FMOC-protected amino acid derivatives. Isocyanates 7, formed in situ, could be coupled directly to a solid support functionalized with amine groups or to amino acids anchored on resins using CH{sub 2}Cl{sub 2} as solvent and an 11 h coupling time at 25 {degree}C. Such couplings afforded peptidomimetics with an N-phthaloyl group at the N-terminus. The optimal conditions identified for removal of the N-phthaloyl group were to use 60% hydrazine in DMF for 1-3 h. Several sequences of amino acids coupled to ureas (`peptidic ureas`) and of sequential urea units (`oligoureas`) were prepared via solid phase syntheses and isolated by HPLC. Partition coefficients were measured for two of these peptidomimetics, and their water solubilities were found to be similar to the corresponding peptides. A small library of 160 analogues of the YGGFL-amide sequence was prepared via Houghten`s tea bag methodology. This library was tested for binding to the anti-{beta}-endorphin monoclonal antibody. Overall, this paper describes methodology for solid phase syntheses of oligourea derivatives with side chains corresponding to some of the protein amino acids. The chemistry involved is ideal for high-throughput syntheses and screening operations. 51 refs., 3 figs., 2 tabs.

  9. The effects of Α-tocopherol and ascorbic acid glucosides on radiation- and H2O2-induced decomposition of thymine in aqueous solution

    International Nuclear Information System (INIS)

    Brinkevich, S.D.; Lagutin, P.Yu.; Shadyro, O.I.

    2008-01-01

    The effects of ascorbic acid, ascorbic acid glycoside and α-tocopherol monoglycoside on radiation- and H 2 O 2 -induced decomposition of thymine in aqueous solutions were investigated. Of the three compounds studied, ascorbic acid glycoside was found to possess the most marked protecting properties. An explanation of this phenomenon has been given in terms of differences in molecular structures of ascorbic acid and ascorbic acid glycoside, as well as properties of radical adducts formed during their interaction with OH radicals. (authors)

  10. Characterization of antioxidant enzymes and peroxisomes of olive (Olea europaea L.) fruits.

    Science.gov (United States)

    Lopez-Huertas, Eduardo; del Río, Luis A

    2014-10-15

    The presence of peroxisomes in olive (Olea europaea L.) fruits and different antioxidant enzymes occurring in this plant tissue is reported for the first time. Ultrastructural analysis showed that olive cells were characterized by the presence of large vacuoles and lipid drops. Plastids, mitochondria and peroxisomes were placed near the cell wall, showing some type of association with it. Olive fruit peroxisomes were purified by sucrose density-gradient centrifugation, and catalase, glutathione reductase and ascorbate peroxidase were found in peroxisomes. In olive fruit tissue the presence of a battery of antioxidant enzymes was demonstrated, including catalase, four superoxide dismutase isozymes (mainly an Fe-SOD plus 2 Cu,Zn-SOD and a Mn-SOD), all the enzymes of the ascorbate-glutathione cycle, reduced and oxidized glutathione, ascorbate, and four NADPH-recycling dehydrogenases. The knowledge of the full composition of antioxidants (enzymatic and non-enzymatic) in olive fruits is crucial to be able to understand the processes regulating the antioxidant composition of olive oil. Copyright © 2014 Elsevier GmbH. All rights reserved.

  11. Kinetics of degradation of ascorbic acid by cyclic voltammetry method

    Directory of Open Access Journals (Sweden)

    Grudić Veselinka V.

    2015-01-01

    Full Text Available Cyclic voltammetry was used to examine the kinetics of degradation of ascorbic acid (AA at different temperatures. It has been shown that the reduction of the concentration of AA in all temperatures follow the kinetics of the first order reaction. The rate constant of the oxidation reaction increases with temperature as follows: 5x10-5; 2x10-4; 1x10-3 and 3x10-3 min-1 at temperatures of 25°C, 35°C, 65°C and 90°C, respectively. The temperature dependence of the rate constant follows Arrhenius equation, and the value of activation energy of the reaction degradation is 48.2 kJ mol-1 . The effect of storage time at a temperature of 90 °C on AA content in fresh juice of green peppers was investigated. It was shown that AA oxidation reaction in the juice is also the first order reaction, while the lower rate constant in relation to the pure AA (5x10-3 min-1 indicates the influence of other substances present in peppers.

  12. Ascorbic acid (AA) metabolism in protection against radiation damage

    International Nuclear Information System (INIS)

    Rose, R.C.; Koch, M.J.

    1986-01-01

    The possibility is considered that AA protects tissues against radiation damage by scavenging free radicals that result from radiolysis of water. A physiologic buffer (pH 6.7) was incubated with 14 C-AA and 1 mM thiourea (to slow spontaneous oxidation of AA). Aliquots were assayed by HPLC and scintillation spectrometry to identify the 14 C-label. Samples exposed to Cobalt-60 radiation had a half time of AA decay of 30 minutes) indicating that AA scavenges radiation-induced free radicals and forms the ascorbate free radical (AFR). Pairs of 14 C-AFR disproportionate, with the net effect of 14 C-dehydroascorbic acid formation from 14 C-AA. Having established that AFR result from ionizing radiation in an aqueous solution, the possibility was evaluated that a tissue factor reduces AFR. Cortical tissue from the kidneys of male rats was minced, homogenized in buffer and centrifuged at 8000 xg. The supernatant was found to slow the rate of radiation-induced AA degradation by > 90% when incubated at 23 0 C in the presence of 15 μM 14 C-AA. Samples of supernatant maintained at 100 0 C for 10 minutes or precipitated with 5% PCA did not prevent radiation-induced AA degradation. AA may have a specific role in scavenging free radicals generated by ionizing radiation and thereby protect body tissues

  13. Kinetics of ascorbic acid degradation in un-pasteurized Iranian lemon juice during regular storage conditions.

    Science.gov (United States)

    Abbasi, A; Niakousari, M

    2008-05-15

    The aim of this research was to determine shelf life stability of un-pasteurized lemon juice filled in clear or dark green glass bottles. Presence of light, time and temperature affect the ascorbic acid retention in citrus juices. Bottles were stored at room temperature (27 +/- 3 degrees C) and in the refrigerator (3 +/- 1 degrees C). Total soluble solids, total titrable acidity and pH value were measured every three weeks and analysis was carried out on ascorbic acid content by means of titration method in the presence of 2,6-dichlorophenol indophenol. The study was carried out for 12 weeks after which slight changes in color, taste and apparent texture in some samples were observed and ascorbic acid content reduced by 50%. Soluble solids content, pH value and total acidity were 5.5 degrees Brix, 2.73 and 5 g/100 mL, respectively which appeared not to be significantly influenced by storage time or conditions. Ascorbic acid content initially at 38.50 mg/100 mL was sharply reduced to about 22 mg/100 mL within the first three weeks of storage. The final ascorbic acid content of all samples was about 15 mg/100 mL. The deteriorative reaction of ascorbic acid in the juice at all conditions followed a first-order kinetic model with activation energy of 137 cal mol(-1).

  14. Ascorbate enhances u.v.-mutagenesis in E. coli but inhibits it in Chinese hamster cells

    International Nuclear Information System (INIS)

    Rossman, T.G.; Klein, C.B.; Naslund, M.

    1986-01-01

    Ascorbic acid (vitamin C) causes an increase in the mutation frequency of u.v.-irradiated Escherichia coli WP2. The enhancement occurs at all u.v. fluences, and is dependent upon the ascorbate concentration in the medium. A maximum effect (approx. 8- to 13-fold) is seen at 100-150 μg/ml, although some enhancement can be seen even at 10 μg/ml. The comutagenic effect of ascorbate with u.v. in E. coli is dependent upon peptone, a constituent of nutrient broth. The enhancement of u.v.-mutagenesis by ascorbate is absent in strains WP2sub(s) (uvrA) amd WP6 (polA), suggesting that ascorbate affects the repair of pyrimidine dimers. The opposite results are observed for u.v.-mutagenesis in Chinese hamster V79 cells. The presence of ascorbate (50 μg/ml) during u.v. irradiation does not enhance the u.v. effect, but rather decreases it approx. 30%. These results are discussed with regard to differences in the mechanism of u.v.-mutagenesis and DNA repair in bacterial and mammalian cells. (author)

  15. A highly sensitive kinetic spectrophotometric method for the determination of ascorbic Acid in pharmaceutical samples.

    Science.gov (United States)

    Shishehbore, Masoud Reza; Aghamiri, Zahra

    2014-01-01

    In this study, a new reaction system for quantitative determination of ascorbic acid was introduced. The developed method is based on inhibitory effect of ascorbic acid on the Orange G-bromate system. The change in absorbance was followed spectrophotometrically at 478 nm. The dependence of sensitivity on the reaction variables including reagents concentration, temperature and time was investigated. Under optimum experimental conditions, calibration curve was linear over the range 0.7 - 33.5 μg mL(-1) of ascorbic acid including two linear segments and the relative standard deviations (n = 6) for 5.0 and 20.0 μg mL(-1) of ascorbic acid were 1.08 and 1.02%, respectively. The limit of detection was 0.21 μg mL(-) (1) of ascorbic acid. The effect of diverse species was also investigated. The developed method was successfully applied for the determination of ascorbic acid in pharmaceutical samples. The results were in a good agreement with those of reference method.

  16. Ascorbic acid prevents vascular dysfunction induced by oral glucose load in healthy subjects.

    Science.gov (United States)

    De Marchi, Sergio; Prior, Manlio; Rigoni, Anna; Zecchetto, Sara; Rulfo, Fanny; Arosio, Enrico

    2012-01-01

    To examine the effects of oral glucose load on forearm circulatory regulation before and after ascorbic acid administration in healthy subjects. Microcirculation study with laser Doppler was performed at the hand in basal conditions, after ischemia and after acetylcholine and nitroprusside; strain gauge plethysmography was performed at basal and after ischemia. The tests were repeated in the same sequence 2 hour after oral administration of glucose (75 g). The subjects were randomised for administration of ascorbic acid (1 g bid) or placebo (sodium bicarbonate 1 g bid) for 10 days. After that, the tests were repeated before and after a new oral glucose load. Blood pressure and heart rate were monitored. Macrocirculatory flux, pressure values and heart rate were unvaried throughout the study. The glucose load caused a reduction in the hyperemic peak flow with laser Doppler and plethysmography; it reduced flux recovery time and hyperemic curve area after ischemia; acetylcholine elicited a minor increase in flux with laser Doppler. The response to nitroprusside was unvaried after glucose load as compared to basal conditions. Treatment with ascorbic acid prevented the decrease in hyperemia after glucose, detected with laser Doppler and plethysmography. Ascorbic acid prevented the decreased response to acetylcholine after glucose, the response to nitroprusside was unaffected by ascorbic acid. Results after placebo were unvaried. Oral glucose load impairs endothelium dependent dilation and hyperaemia at microcirculation, probably via oxidative stress; ascorbic acid can prevent it. Copyright © 2011 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.

  17. Application of titanium oxide nanotube films containing gold nanoparticles for the electroanalytical determination of ascorbic acid

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini, Mir Ghasem, E-mail: mg-hosseini@tabrizu.ac.ir; Faraji, Masoud; Momeni, Mohamad Mohsen

    2011-03-31

    Au/TiO{sub 2}/Ti electrodes have been prepared by galvanic deposition of gold particles on TiO{sub 2} nanotube substrates. Titanium oxide nanotubes are fabricated by anodizing titanium foil in a Dimethyl Sulfoxide electrolyte containing fluoride. The scanning electron microscopy results indicated that gold particles are homogeneously deposited on the surface of TiO{sub 2} nanotubes. The TiO{sub 2} layers consist of individual tubes of about 40-80 nm diameters. The electro-catalytic behavior of Au/TiO{sub 2}/Ti and flat gold electrodes for the ascorbic acid electro-oxidation was studied by cyclic voltammetry. The results showed that the flat gold electrode is not suitable for the oxidation of ascorbic acid. However, the Au/TiO{sub 2}/Ti electrodes are shown to possess catalytic activity toward the oxidation reaction. Catalytic oxidation peak current showed a linear dependence on the ascorbic acid concentration and a linear calibration curve is obtained in the concentration range of 1-5 mM of ascorbic acid. Also, determination of ascorbic acid in real samples was evaluated. The obtained results were found to be satisfactory. Finally the effects of interference on the detection of ascorbic acid were investigated.

  18. Ascorbic acid enables reversible dopamine receptor 3H-agonist binding

    International Nuclear Information System (INIS)

    Leff, S.; Sibley, D.R.; Hamblin, M.; Creese, I.

    1981-01-01

    The effects of ascorbic acid on dopaminergic 3 H-agonist receptor binding were studied in membrane homogenates of bovine anterior pituitary and caudate, and rat striatum. In all tissues virtually no stereospecific binding (defined using 1uM (+)butaclamol) of the 3 H-agonists N-propylnorapomorphine (NPA), apomorphine, or dopamine could be demonstrated in the absence of ascorbic acid. Although levels of total 3 H-agonist binding were three to five times greater in the absence than in the presence of 0.1% ascorbic acid, the increased binding was entirely non-stereospecific. Greater amounts of dopamine-inhibitable 3 H-NPA binding could be demonstrated in the absence of 0.1% ascorbic acid, but this measure of ''specific binding'' was demonstrated not to represent dopamine receptor binding since several other catecholamines and catechol were equipotent with dopamine and more potent than the dopamine agonist (+/-)amino-6,7-dihydroxy-1,2,3,4-tetrahydronapthalene (ADTN) in inhibiting this binding. High levels of dopamine-displaceable 3 H-agonist binding were detected in fresh and boiled homogenates of cerebellum, an area of brain which receives no dopaminergic innervation, further demonstrating the non-specific nature of 3 H-agonist binding in the absence of ascorbic acid. These studies emphasize that under typical assay conditions ascorbic acid is required in order to demonstrate reversible and specific 3 H-agonist binding to dopamine receptors

  19. Pretreatment with ascorbic acid prevents lethal gastrointestinal syndrome in mice receiving a massive amount of radiation

    International Nuclear Information System (INIS)

    Yamamoto, Tetsuo; Kinoshita, Manabu; Shinomiya, Nariyoshi; Hiroi, Sadayuki; Sugasawa, Hidekazu; Majima, Takashi; Seki, Shuhji; Matsushita, Yoshitaro; Saitoh, Daizoh

    2010-01-01

    While bone marrow or stem cell transplantation can rescue bone marrow aplasia in patients accidentally exposed to a lethal radiation dose, radiation-induced irreversible gastrointestinal damage (GI syndrome) is fatal. We investigated the effects of ascorbic acid on radiation-induced GI syndrome in mice. Ascorbic acid (150 mg/kg/day) was orally administered to mice for 3 days, and then the mice underwent whole body irradiation (WBI). Bone marrow transplantation (BMT) 24 h after irradiation rescued mice receiving a WBI dose of less than 12 Gy. No mice receiving 14 Gy-WBI survived, because of radiation-induced GI syndrome, even if they received BMT. However, pretreatment with ascorbic acid significantly suppressed radiation-induced DNA damage in the crypt cells and prevented denudation of intestinal mucosa; therefore, ascorbic acid in combination with BMT rescued mice after 14 Gy-WBI. DNA microarray analysis demonstrated that irradiation up-regulated expressions of apoptosis-related genes in the small intestine, including those related to the caspase-9-mediated intrinsic pathway as well as the caspase-8-mediated extrinsic pathway, and down-regulated expressions of these genes in ascorbic acid-pretreated mice. Thus, pretreatment with ascorbic acid may effectively prevent radiation-induced GI syndrome. (author)

  20. Combined effect of selenium and ascorbic acid on alcohol induced hyperlipidemia in male guinea pigs.

    Science.gov (United States)

    Asha, G S; Indira, M

    2004-02-01

    Alcoholics usually suffer from malnutrition and are especially deficient in micronutrients like vitamin C, selenium and Zn. In the present study, combined effects of selenium and ascorbic acid on alcohol-induced hyperlipidemia were studied in guinea pigs. Four groups of male guinea pigs were maintained for 45 days as follows: control (1 mg ascorbate (AA)/100 g body mass/day), ethanol (900 mg ethanol/100 g body mass + 1 mg AA/100 g body mass/day), selenium+ascorbic acid [(25 mg AA + 0.05 mg Se)/100 g body mass/day], ethanol+selenium+ascorbic acid [(25 mg AA + 0.05 mg Se + 900 mg ethanol)/100 g body mass/day]. Co-administration of selenium and ascorbic acid along with alcohol reduced the concentration of all lipids, as also evidenced from the decreased activities of hydroxymethylglutaryl-CoA reductase and enhanced activities of plasma lecithin cholesterol acyl transferase and lipoprotein lipase. Concentrations of bile acids were increased. We conclude that the supplementation of Se and ascorbic acid reduced alcohol induced hyperlipidemia, by decreased synthesis and increased catabolism.

  1. Old Things New View: Ascorbic Acid Protects the Brain in Neurodegenerative Disorders

    Directory of Open Access Journals (Sweden)

    Adriana Covarrubias-Pinto

    2015-11-01

    Full Text Available Ascorbic acid is a key antioxidant of the Central Nervous System (CNS. Under brain activity, ascorbic acid is released from glial reservoirs to the synaptic cleft, where it is taken up by neurons. In neurons, ascorbic acid scavenges reactive oxygen species (ROS generated during synaptic activity and neuronal metabolism where it is then oxidized to dehydroascorbic acid and released into the extracellular space, where it can be recycled by astrocytes. Other intrinsic properties of ascorbic acid, beyond acting as an antioxidant, are important in its role as a key molecule of the CNS. Ascorbic acid can switch neuronal metabolism from glucose consumption to uptake and use of lactate as a metabolic substrate to sustain synaptic activity. Multiple evidence links oxidative stress with neurodegeneration, positioning redox imbalance and ROS as a cause of neurodegeneration. In this review, we focus on ascorbic acid homeostasis, its functions, how it is used by neurons and recycled to ensure antioxidant supply during synaptic activity and how this antioxidant is dysregulated in neurodegenerative disorders.

  2. Ascorbate-dependent impact on cell-derived matrix in modulation of stiffness and rejuvenation of infrapatellar fat derived stem cells toward chondrogenesis.

    Science.gov (United States)

    Pizzute, Tyler; Zhang, Ying; He, Fan; Pei, Ming

    2016-08-10

    Developing an in vitro microenvironment using cell-derived decellularized extracellular matrix (dECM) is a promising approach to efficiently expand adult stem cells for cartilage engineering and regeneration. Ascorbic acid serves as a critical stimulus for cells to synthesize collagens, which constitute the major component of dECM. In this study, we hypothesized that optimization of ascorbate treatment would maximize the rejuvenation effect of dECM on expanded stem cells from human infrapatellar fat pad in both proliferation and chondrogenic differentiation. In the duration regimen study, we found that dECM without L-ascorbic acid phosphate (AA) treatment, exhibiting lower stiffness measured by atomic force microscopy, yielded expanded cells with higher proliferation capacity but lower chondrogenic potential when compared to those with varied durations of AA treatment. dECM with 250 µM of AA treatment for 10 d had better rejuvenation in chondrogenic capacity if the deposited cells were from passage 2 rather than passage 5, despite no significant difference in matrix stiffness. In the dose regimen study, we found that dECMs deposited by varied concentrations of AA yielded expanded cells with higher proliferation capacity despite lower expression levels of stem cell related surface markers. Compared to cells expanded on tissue culture polystyrene, those on dECM exhibited greater chondrogenic potential, particularly for the dECMs with 50 µM and 250 µM of AA treatment. With the supplementation of ethyl-3,4-dihydroxybenzoate (EDHB), an inhibitor targeting procollagen synthesis, the dECM with 50 µM of AA treatment exhibited a dramatic decrease in the rejuvenation effect of expanded cell chondrogenic potential at both mRNA and protein levels despite no significant difference in matrix stiffness. Defined AA treatments during matrix preparation will benefit dECM-mediated stem cell engineering and future treatments for cartilage defects.

  3. Translational control of an intestinal microvillar enzyme

    DEFF Research Database (Denmark)

    Danielsen, E M; Cowell, G M; Sjöström, H

    1986-01-01

    The rates of biosynthesis of adult and foetal pig small-intestinal aminopeptidase N (EC 3.4.11.2) were compared to determine at which level the expression of the microvillar enzyme is developmentally controlled. In organ-cultured explants, the rate of biosynthesis of foetal aminopeptidase N is only...... about 3% of the adult rate. The small amount synthesized occurs in a high-mannose-glycosylated, membrane-bound, form that is processed to the mature, complex-glycosylated, form at a markedly slower rate than that of the adult enzyme. Extracts of total RNA from adult and foetal intestine contained...

  4. Synthesis of novel amperometric urea-sensor using hybrid synthesized NiO-NPs/GO modified GCE in aqueous solution of cetrimonium bromide.

    Science.gov (United States)

    Parsaee, Zohreh

    2018-06-01

    In this study NiO nanostructures were synthesized via combinational synthetic method (ultrasound-assisted biosynthesis) and immobilized on the glassy carbon electrode (GCE) as a highly sensitive and selective enzyme-less sensor for urea detection. NiO-NPs were fully characterized using SEM, EDX, XRD, BET, TGA, FT-IR, UV-vis and Raman methods which revealed the formation of NiO nanostructures in the form of cotton like porous material and crystalline in nature with the average size of 3.8 nm. GCE was modified with NiO-NPs in aqueous solution of cetrimonium bromide(CTAB). Highly adhesive NiO/CTAB/GO nanocomposite membrane has been formed on GCE by immersing NiO/CTAB modified GCE in GO suspension. CTAB has a major role in the production and immobilization of the nanocomposites on the GCE surface and the binding NiO nanoparticles on GO plates. In addition, CTAB/GO composition made a highly adhesive surface on the GCE. The resulting NiO/CTAB/GO/GCE contains potently sensitive to urea in aqueous environments. The response of as developed amperometric sensor was linear in the range of 100-1200 µM urea with R 2 value of 0.991 and limit of detection (LOD), 8 µM. The sensor responded negligibly to various interfering species like glucose, uric acid and ascorbic acid. This sensor was applied successfully for determining urea in real water samples such as mineral water, tap water and river water with acceptable recovery. Copyright © 2018 Elsevier B.V. All rights reserved.

  5. Contemplation of wheat genotypes for enhanced antioxidant enzyme activity

    International Nuclear Information System (INIS)

    Nasim, S.; Shabbir, G.; Ilyas, M.

    2017-01-01

    Wheat (Triticum aestivum L.) is leading cereal crop in Pakistan but its yield is highly affected due to various abiotic factors especially drought stress, which affects the metabolism of plants. The present study was conducted at Pir Mehr Ali Shah Arid Agriculture University Rawalpindi, using thirty three genotypes during 2011 to investigate the response of anti oxidative enzymes. Seedlings were subjected to stress condition with 30 % PEG 6000 solution along with control (irrigated with water) under in vitro conditions. The experiment was conducted in pots following Complete Randomized Design in Laboratory. Results revealed that under control conditions the maximum values for Guaiacol peroxidase were found in Punjab-96 and Auqab-2000 (2.523), for superoxide in C-273 (0.294), for ascorbate peroxide in PAK-81 (2.523) and for catalase in Kohsar-95 (0.487). Under moisture stress condition the maximum value for Guaiacol peroxidase were recorded for Kohsar-95 (2.699), for superoxide in Kohsar-95 (1.259), for ascorbate peroxide in Pak-81, SA-75, Mexipak-65 and PARI-73 (3.000) and for catalase in Mexipak-65 (0.640). The genotypes which showed higher antioxidant enzyme activity under drought stress have the ability to perform better under adverse soil moisture condition. Such potential genotypes can be utilized in the future breeding programs and also in improving the wheat varieties against drought stress. (author)

  6. Method of synthesizing tungsten nanoparticles

    Science.gov (United States)

    Thoma, Steven G; Anderson, Travis M

    2013-02-12

    A method to synthesize tungsten nanoparticles has been developed that enables synthesis of nanometer-scale, monodisperse particles that can be stabilized only by tetrahydrofuran. The method can be used at room temperature, is scalable, and the product concentrated by standard means. Since no additives or stabilizing surfactants are required, this method is particularly well suited for producing tungsten nanoparticles for dispersion in polymers. If complete dispersion is achieved due to the size of the nanoparticles, then the optical properties of the polymer can be largely maintained.

  7. Optical fusions and proportional syntheses

    Science.gov (United States)

    Albert-Vanel, Michel

    2002-06-01

    A tragic error is being made in the literature concerning matters of color when dealing with optical fusions. They are still considered to be of additive nature, whereas experience shows us somewhat different results. The goal of this presentation is to show that fusions are, in fact, of 'proportional' nature, tending to be additive or subtractive, depending on each individual case. Using the pointillist paintings done in the manner of Seurat, or the spinning discs experiment could highlight this intermediate sector of the proportional. So, let us try to examine more closely what occurs in fact, by reviewing additive, subtractive and proportional syntheses.

  8. Evolutionary selection of enzymatically synthesized semiconductors from biomimetic mineralization vesicles.

    Science.gov (United States)

    Bawazer, Lukmaan A; Izumi, Michi; Kolodin, Dmitriy; Neilson, James R; Schwenzer, Birgit; Morse, Daniel E

    2012-06-26

    The way nature evolves and sculpts materials using proteins inspires new approaches to materials engineering but is still not completely understood. Here, we present a cell-free synthetic biological platform to advance studies of biologically synthesized solid-state materials. This platform is capable of simultaneously exerting many of the hierarchical levels of control found in natural biomineralization, including genetic, chemical, spatial, structural, and morphological control, while supporting the evolutionary selection of new mineralizing proteins and the corresponding genetically encoded materials that they produce. DNA-directed protein expression and enzymatic mineralization occur on polystyrene microbeads in water-in-oil emulsions, yielding synthetic surrogates of biomineralizing cells that are then screened by flow sorting, with light-scattering signals used to sort the resulting mineralized composites differentially. We demonstrate the utility of this platform by evolutionarily selecting newly identified silicateins, biomineralizing enzymes previously identified from the silica skeleton of a marine sponge, for enzyme variants capable of synthesizing silicon dioxide (silica) or titanium dioxide (titania) composites. Mineral composites of intermediate strength are preferentially selected to remain intact for identification during cell sorting, and then to collapse postsorting to expose the encoding genes for enzymatic DNA amplification. Some of the newly selected silicatein variants catalyze the formation of crystalline silicates, whereas the parent silicateins lack this ability. The demonstrated bioengineered route to previously undescribed materials introduces in vitro enzyme selection as a viable strategy for mimicking genetic evolution of materials as it occurs in nature.

  9. Recent advances in rational approaches for enzyme engineering

    Directory of Open Access Journals (Sweden)

    Kerstin Steiner

    2012-09-01

    Full Text Available Enzymes are an attractive alternative in the asymmetric syntheses of chiral building blocks. To meet the requirements of industrial biotechnology and to introduce new functionalities, the enzymes need to be optimized by protein engineering. This article specifically reviews rational approaches for enzyme engineering and de novo enzyme design involving structure-based approaches developed in recent years for improvement of the enzymes’ performance, broadened substrate range, and creation of novel functionalities to obtain products with high added value for industrial applications.

  10. Sensitive spectrophotometric determination of ascorbic acid in drugs and foods using surface plasmon resonance band of silver nanoparticles

    Directory of Open Access Journals (Sweden)

    Kobra Zarei

    2015-12-01

    Full Text Available A simple and sensitive procedure was proposed for spectrophotometric determination of ascorbic acid. It was found that the reduction of Ag+ to silver nanoparticles (Ag-NPs by ascorbic acid in the presence of polyvinylpyrrolidone (PVP as a stabilizing agent produce very intense surface plasmon resonance peak of Ag-NPs. The plasmon absorbance of the Ag-NPs at λ = 440 nm allows the quantitative spectrophotometric detection of the ascorbic acid. The calibration curve was linear with concentration of ascorbic acid in the range of 0.5–60 μM. The detection limit was obtained as 0.08 μM. The influence of potential interfering substances on the determination of ascorbic acid was studied. The proposed method was successfully applied for the determination of ascorbic acid in some powdered drink mixtures, commercial orange juice, natural orange juice, vitamin C injection, effervescent tablet, and multivitamin tablet.

  11. Ascorbate oxidase-dependent changes in the redox state of the apoplast modulate gene transcript accumulation leading to modified hormone signaling and orchestration of defense processes in tobacco.

    Science.gov (United States)

    Pignocchi, Cristina; Kiddle, Guy; Hernández, Iker; Foster, Simon J; Asensi, Amparo; Taybi, Tahar; Barnes, Jeremy; Foyer, Christine H

    2006-06-01

    The role of the redox state of the apoplast in hormone responses, signaling cascades, and gene expression was studied in transgenic tobacco (Nicotiana tabacum) plants with modified cell wall-localized ascorbate oxidase (AO). High AO activity specifically decreased the ascorbic acid (AA) content of the apoplast and altered plant growth responses triggered by hormones. Auxin stimulated shoot growth only when the apoplastic AA pool was reduced in wild-type or AO antisense lines. Oxidation of apoplastic AA in AO sense lines was associated with loss of the auxin response, higher mitogen-activated protein kinase activities, and susceptibility to a virulent strain of the pathogen Pseudomonas syringae. The total leaf glutathione pool, the ratio of reduced glutathione to glutathione disulfide, and glutathione reductase activities were similar in the leaves of all lines. However, AO sense leaves exhibited significantly lower dehydroascorbate reductase and ascorbate peroxidase activities than wild-type and antisense leaves. The abundance of mRNAs encoding antioxidant enzymes was similar in all lines. However, the day/night rhythms in the abundance of transcripts encoding the three catalase isoforms were changed in response to the AA content of the apoplast. Other transcripts influenced by AO included photorespiratory genes and a plasma membrane Ca(2+) channel-associated gene. We conclude that the redox state of the apoplast modulates plant growth and defense responses by regulating signal transduction cascades and gene expression patterns. Hence, AO activity, which modulates the redox state of the apoplastic AA pool, strongly influences the responses of plant cells to external and internal stimuli.

  12. Phytoproteins in green leaves as building blocks for photosynthesis of gold nanoparticles: An efficient electrocatalyst towards the oxidation of ascorbic acid and the reduction of hydrogen peroxide.

    Science.gov (United States)

    Megarajan, Sengan; Ayaz Ahmed, Khan Behlol; Rajendra Kumar Reddy, G; Suresh Kumar, P; Anbazhagan, Veerappan

    2016-02-01

    Herein, we present a simple and green method for the synthesis of gold nanoparticles (AuNPs) using the phytoproteins of spinach leaves. Under ambient sunlight irradiation, the isolated phytoprotein complex from spinach leaves reduces the gold chloride aqueous solution and stabilizes the formed AuNPs. As prepared nanoparticles were characterized by UV-visible spectroscopy, Fourier transform infra-red (FTIR) spectroscopy, zeta potential, transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDS). The surface plasmon resonance (SPR) maximum for AuNPs was observed at 520 nm. The zeta potential value estimated for the AuNPs is -27.0 mV, indicating that the NPs are well separated. Transmission electron micrographs revealed that the particles are spherical in nature with the size range from 10 to 15 nm. AuNPs act as a catalyst in the degradation of an azo dye, methyl orange in an aqueous environment. The reduction rate was determined to be pseudo-first order. Electrocatalytic efficiency of the synthesized AuNPs via this green approach was studied by chronoamperometry using ascorbic acid and hydrogen peroxide as a model compound for oxidation and reduction, respectively. Electrocatalytic studies indicate that the gold nanoparticles can be used to detect ascorbic acid and hydrogen peroxide in micromolar concentrations with response time less than 3s. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Ascorbic acid reduces noise-induced nitric oxide production in the guinea pig ear.

    Science.gov (United States)

    Heinrich, Ulf-Rüdiger; Fischer, Ilka; Brieger, Jürgen; Rümelin, Andreas; Schmidtmann, Irene; Li, Huige; Mann, Wolf J; Helling, Kai

    2008-05-01

    Noise-induced hearing loss can be caused, among other causes, by increased nitric oxide (NO) production in the inner ear leading to nitroactive stress and cell destruction. Some studies in the literature suggest that the degree of hearing loss (HL) could be reduced in an animal model through ascorbic acid supplementation. To identify the effect of ascorbic acid on tissue-dependent NO content in the inner ear of the guinea pig, we determined the local NO production in the organ of Corti and the lateral wall separately 6 hours after noise exposure. Prospective animal study in guinea pigs. Over a period of 7 days, male guinea pigs were supplied with minimum (25 mg/kg body weight/day) and maximum (525 mg/kg body weight/day) ascorbic acid doses, and afterwards exposed to noise (90 dB sound pressure level for 1 hour). The acoustic-evoked potentials were recorded before and after noise exposure. The organ of Corti and the lateral wall were incubated differently for 6 hours in culture medium, and the degree of NO production was determined by chemiluminescence. Ascorbic acid treatment reduced the hearing threshold shift after noise exposure depending on concentration. When the maximum ascorbic acid dose was substituted, NO production was significantly reduced in the lateral wall after noise exposure and slightly reduced in the organ of Corti. Oral supplementation of the natural radical scavenger ascorbic acid reduces the NO-production rate in the inner ear in noisy conditions. This finding supports the concept of inner ear protection by ascorbic acid supplementation.

  14. Ascorbic acid attenuates endothelial permeability triggered by cell-free hemoglobin.

    Science.gov (United States)

    Kuck, Jamie L; Bastarache, Julie A; Shaver, Ciara M; Fessel, Joshua P; Dikalov, Sergey I; May, James M; Ware, Lorraine B

    2018-01-01

    Increased endothelial permeability is central to shock and organ dysfunction in sepsis but therapeutics targeted to known mediators of increased endothelial permeability have been unsuccessful in patient studies. We previously reported that cell-free hemoglobin (CFH) is elevated in the majority of patients with sepsis and is associated with organ dysfunction, poor clinical outcomes and elevated markers of oxidant injury. Others have shown that Vitamin C (ascorbate) may have endothelial protective effects in sepsis. In this study, we tested the hypothesis that high levels of CFH, as seen in the circulation of patients with sepsis, disrupt endothelial barrier integrity. Human umbilical vein endothelial cells (HUVEC) were grown to confluence and treated with CFH with or without ascorbate. Monolayer permeability was measured by Electric Cell-substrate Impedance Sensing (ECIS) or transfer of 14 C-inulin. Viability was measured by trypan blue exclusion. Intracellular ascorbate was measured by HPLC. CFH increased permeability in a dose- and time-dependent manner with 1 mg/ml of CFH increasing inulin transfer by 50% without affecting cell viability. CFH (1 mg/ml) also caused a dramatic reduction in intracellular ascorbate in the same time frame (1.4 mM without CFH, 0.23 mM 18 h after 1 mg/ml CFH, p < 0.05). Pre-treatment of HUVECs with ascorbate attenuated CFH induced permeability. CFH increases endothelial permeability in part through depletion of intracellular ascorbate. Supplementation of ascorbate can attenuate increases in permeability mediated by CFH suggesting a possible therapeutic approach in sepsis. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Enzyme inhibition by iminosugars

    DEFF Research Database (Denmark)

    López, Óscar; Qing, Feng-Ling; Pedersen, Christian Marcus

    2013-01-01

    Imino- and azasugar glycosidase inhibitors display pH dependant inhibition reflecting that both the inhibitor and the enzyme active site have groups that change protonation state with pH. With the enzyme having two acidic groups and the inhibitor one basic group, enzyme-inhibitor complexes...

  16. Modeling nitrous oxide production and reduction in soil through explicit representation of denitrification enzyme kinetics.

    Science.gov (United States)

    Zheng, Jianqiu; Doskey, Paul V

    2015-02-17

    An enzyme-explicit denitrification model with representations for pre- and de novo synthesized enzymes was developed to improve predictions of nitrous oxide (N2O) accumulations in soil and emissions from the surface. The metabolic model of denitrification is based on dual-substrate utilization and Monod growth kinetics. Enzyme synthesis/activation was incorporated into each sequential reduction step of denitrification to regulate dynamics of the denitrifier population and the active enzyme pool, which controlled the rate function. Parameterizations were developed from observations of the dynamics of N2O production and reduction in soil incubation experiments. The model successfully reproduced the dynamics of N2O and N2 accumulation in the incubations and revealed an important regulatory effect of denitrification enzyme kinetics on the accumulation of denitrification products. Pre-synthesized denitrification enzymes contributed 20, 13, 43, and 62% of N2O that accumulated in 48 h incubations of soil collected from depths of 0-5, 5-10, 10-15, and 15-25 cm, respectively. An enzyme activity function (E) was defined to estimate the relative concentration of active enzymes and variation in response to environmental conditions. The value of E allows for activities of pre-synthesized denitrification enzymes to be differentiated from de novo synthesized enzymes. Incorporating explicit representations of denitrification enzyme kinetics into biogeochemical models is a promising approach for accurately simulating dynamics of the production and reduction of N2O in soils.

  17. Multigene families encode the major enzymes of antioxidant metabolism in Eucalyptus grandis L

    Directory of Open Access Journals (Sweden)

    Felipe Karam Teixeira

    2005-01-01

    Full Text Available Antioxidant metabolism protects cells from oxidative damage caused by reactive oxygen species (ROS. In plants, several enzymes act jointly to maintain redox homeostasis. Moreover, isoform diversity contributes to the fine tuning necessary for plant responses to both exogenous and endogenous signals influencing antioxidant metabolism. This study aimed to provide a comprehensive view of the major classes of antioxidant enzymes in the woody species Eucalyptus grandis. A careful survey of the FORESTs data bank revealed 36 clusters as encoding antioxidant enzymes: six clusters encoding ascorbate peroxidase (APx isozymes, three catalase (CAT proteins, three dehydroascorbate reductase (DHAR, two glutathione reductase (GR isozymes, four monodehydroascorbate reductase (MDHAR, six phospholipid hydroperoxide glutathione peroxidases (PhGPx, and 12 encoding superoxide dismutases (SOD isozymes. Phylogenetic analysis demonstrated that all clusters (identified herein grouped with previously characterized antioxidant enzymes, corroborating the analysis performed. With respect to enzymes involved in the ascorbate-glutathione cycle, both cytosolic and chloroplastic isoforms were putatively identified. These sequences were widely distributed among the different ESTs libraries indicating a broad gene expression pattern. Overall, the data indicate the importance of antioxidant metabolism in eucalyptus.

  18. Exogenous Spermidine Alleviates Low Temperature Injury in Mung Bean (Vigna radiata L. Seedlings by Modulating Ascorbate-Glutathione and Glyoxalase Pathway

    Directory of Open Access Journals (Sweden)

    Kamrun Nahar

    2015-12-01

    Full Text Available The role of exogenous spermidine (Spd in alleviating low temperature (LT stress in mung bean (Vigna radiata L. cv. BARI Mung-3 seedlings has been investigated. Low temperature stress modulated the non-enzymatic and enzymatic components of ascorbate-glutathione (AsA-GSH cycle, increased H2O2 content and lipid peroxidation, which indicate oxidative damage of seedlings. Low temperature reduced the leaf relative water content (RWC and destroyed leaf chlorophyll, which inhibited seedlings growth. Exogenous pretreatment of Spd in LT-affected seedlings significantly increased the contents of non-enzymatic antioxidants of AsA-GSH cycle, which include AsA and GSH. Exogenous Spd decreased dehydroascorbate (DHA, increased AsA/DHA ratio, decreased glutathione disulfide (GSSG and increased GSH/GSSG ratio under LT stress. Activities of AsA-GSH cycle enzymes such as ascorbate peroxidase (APX, monodehydroascorbate reductase (MDHAR, dehydroascorbate reductase (DHAR and glutathione reductase (GR increased after Spd pretreatment in LT affected seedlings. Thus, the oxidative stress was reduced. Protective effects of Spd are also reflected from reduction of methylglyoxal (MG toxicity by improving glyoxalase cycle components, and by maintaining osmoregulation, water status and improved seedlings growth. The present study reveals the vital roles of AsA-GSH and glyoxalase cycle in alleviating LT injury.

  19. Thermal degradation kinetics of ascorbic acid, thiamine and riboflavin in rosehip (Rosa canina L nectar

    Directory of Open Access Journals (Sweden)

    Çetin KADAKAL

    2017-10-01

    Full Text Available Abstract In this paper, the loss of L-ascorbic acid, thiamine and riboflavin in rosehip nectar with the heating periods (0, 5, 10, 15, 20 and 30 min at temperatures ranging from 70 to 95 °C is analyzed and experimental results are presented. Firstly, dried rosehip fruits were processed to rosehip nectar and then thermal treatment is performed. Liquid chromatographic (HPLC method was used for the analysis of the contents of L-ascorbic acid, thiamine and riboflavin and examined compounds are thoroughly separated within 25 min. During thermal processing, degradation of L-ascorbic acid, thiamine and riboflavin in rosehip nectar were fitted to a first-order reaction kinetic model. Arrhenius relationship was used for the description of temperature dependence of reaction. Activation energies for L-ascorbic acid, thiamine and riboflavin between 70 to 95 ºC were found to be 55.30, 36.38 and 37.15 kJ/mol, respectively. To the best of the author’s knowledge, due to lack of study on the thermal degradation of L-ascorbic acid, thiamine and riboflavin in rosehip nectar, this manuscript will be the first reported study to enable future analysis.

  20. Sequential injection redox or acid-base titration for determination of ascorbic acid or acetic acid.

    Science.gov (United States)

    Lenghor, Narong; Jakmunee, Jaroon; Vilen, Michael; Sara, Rolf; Christian, Gary D; Grudpan, Kate

    2002-12-06

    Two sequential injection titration systems with spectrophotometric detection have been developed. The first system for determination of ascorbic acid was based on redox reaction between ascorbic acid and permanganate in an acidic medium and lead to a decrease in color intensity of permanganate, monitored at 525 nm. A linear dependence of peak area obtained with ascorbic acid concentration up to 1200 mg l(-1) was achieved. The relative standard deviation for 11 replicate determinations of 400 mg l(-1) ascorbic acid was 2.9%. The second system, for acetic acid determination, was based on acid-base titration of acetic acid with sodium hydroxide using phenolphthalein as an indicator. The decrease in color intensity of the indicator was proportional to the acid content. A linear calibration graph in the range of 2-8% w v(-1) of acetic acid with a relative standard deviation of 4.8% (5.0% w v(-1) acetic acid, n=11) was obtained. Sample throughputs of 60 h(-1) were achieved for both systems. The systems were successfully applied for the assays of ascorbic acid in vitamin C tablets and acetic acid content in vinegars, respectively.

  1. Effect of sodium ascorbate and sodium nitrite on protein and lipid oxidation in dry fermented sausages.

    Science.gov (United States)

    Berardo, A; De Maere, H; Stavropoulou, D A; Rysman, T; Leroy, F; De Smet, S

    2016-11-01

    The effects of sodium nitrite and ascorbate on lipid and protein oxidation were studied during the ripening process of dry fermented sausages. Samples were taken at day 0, 2, 8, 14, 21 and 28 of ripening to assess lipid (malondialdehyde) and protein (carbonyls and sulfhydryl groups) oxidation. Sodium ascorbate and nitrite were separately able to reduce the formation of malondialdehyde. Their combined addition resulted in higher amounts of carbonyl compounds compared to their separate addition or the treatment without any of both compounds. Moreover, sodium nitrite limited the formation of γ-glutamic semialdehyde whereas sodium ascorbate showed a pro-oxidant effect. A loss of thiol groups was observed during ripening, which was not affected by the use of sodium ascorbate nor sodium nitrite. In conclusion, sodium nitrite and ascorbate affected protein and lipid oxidation in different manners. The possible pro-oxidant effect of their combined addition on carbonyl formation might influence the technological and sensory properties of these products. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Methemoglobinemia and ascorbate deficiency in hemoglobin E β thalassemia: metabolic and clinical implications

    Science.gov (United States)

    Allen, Angela; Fisher, Christopher; Premawardhena, Anuja; Bandara, Dayananda; Perera, Ashok; Allen, Stephen; St Pierre, Timothy; Olivieri, Nancy

    2012-01-01

    During investigations of the phenotypic diversity of hemoglobin (Hb) E β thalassemia, a patient was encountered with persistently high levels of methemoglobin associated with a left-shift in the oxygen dissociation curve, profound ascorbate deficiency, and clinical features of scurvy; these abnormalities were corrected by treatment with vitamin C. Studies of erythropoietin production before and after treatment suggested that, as in an ascorbate-deficient murine model, the human hypoxia induction factor pathway is not totally dependent on ascorbate levels. A follow-up study of 45 patients with HbE β thalassemia showed that methemoglobin levels were significantly increased and that there was also a significant reduction in plasma ascorbate levels. Haptoglobin levels were significantly reduced, and the high frequency of the 2.2 haptoglobin genotype may place an additional pressure on ascorbate as a free-radical scavenger in this population. There was, in addition, a highly significant correlation between methemoglobin levels, splenectomy, and factors that modify the degree of globin-chain imbalance. Because methemoglobin levels are modified by several mechanisms and may play a role in both adaptation to anemia and vascular damage, there is a strong case for its further study in other forms of thalassemia and sickle-cell anemia, particularly when splenic function is defective. PMID:22885163

  3. Electrochemical oxidation of ascorbic acid mediated by carbon nano tubes/ Li+/ carbon paste modified solid electrode

    International Nuclear Information System (INIS)

    Goh, J.K.; Tan, W.T.

    2008-01-01

    Multi-walled carbon nano tube (MWCNT) was used to modify BPPG electrode because of its unique structure and extraordinary properties. MWCNT modified electrode exhibited obvious enhancing and electro catalyzing effects to the oxidation of ascorbic acid using cyclic voltammetry technique. MWCNT was bonded on BPPG electrode surface using carbon paste with ratio of 30 % (w/ W) carbon paste (binder): 70 % (w/ w) MWCNT. This method of modification has lowered the capacitance background current and enabled lower detection limit of ascorbic acid concentration. The electrical conductivity property of MWCNT modified electrode was further improved with the intercalation with lithium ion and resulted in current enhancement of 2 times on the oxidation current of ascorbic acid. Parameters of pH and temperature showed significant relation to the sensitivity of MWCNT modified electrode. Under the optimized parameters, the calibration curve constructed was linear up from 50 μM to 5 mM with sensitivity of 34.5 mA M -1 . The practical application of MWCNT modified electrode was demonstrated with Vitamin C pill and orange juice. Good reproducibility and recovery of ascorbic acid concentration showed the feasibility of MWCNT modified electrode to be used in the detection of ascorbic acid in aqueous solution. This also proposed MWCNT modified BPPG electrode possessed advantages such as low detection limit, high stability, low cost and simplicity in fabrication. (author)

  4. Arsenic-induced toxicity and the protective role of ascorbic acid in mouse testis

    International Nuclear Information System (INIS)

    Chang, Soo Im; Jin, Bohwan; Youn, Pilju; Park, Changbo; Park, Jung-Duck; Ryu, Doug-Young

    2007-01-01

    Oxidative stress has been suggested to be a major cause of male reproductive failure. Here, we investigated whether arsenic, which impairs male reproductive functions in rodent models, acts by inducing oxidative stress. Male 8-week-old ICR mice were given drinking water containing 20 or 40 mg/l sodium arsenite with or without 0.75 or 1.5 g/l of the antioxidant ascorbic acid for 5 weeks. The arsenic-treated mice showed decreased epididymidal sperm counts and testicular weights compared to untreated mice. These effects were reversed in mice that were co-treated with ascorbic acid. Similarly, arsenic treatment lowered the activities of testicular 3β-hydroxysteroid dehydrogenase (HSD) and 17β-HSD, which play important roles in steroidogenesis, and this was reversed by co-treatment with ascorbic acid. The testicles of arsenic-treated mice had decreased glutathione (GSH) levels (which correlate inversely with the degree of cellular oxidative stress) and elevated levels of protein carbonyl (a marker of oxidative damage to tissue proteins). Ascorbic acid co-treatment reversed both of these effects. Thus, ascorbic acid blocks both the adverse effects of arsenic on male reproductive functions and the arsenic-induced testicular oxidative changes. These observations support the notion that arsenic impairs male reproductive function by inducing oxidative stress

  5. Ascorbic acid glycation of lens proteins produces UVA sensitizers similar to those in human lens

    International Nuclear Information System (INIS)

    Ortwerth, B.J.; Linetsky, Mikhail; Olesen, P.R.

    1995-01-01

    Soluble calf lens proteins were extensively glycated during a 4 week incubation with ascorbic acid in the presence of oxygen. Amino acids analysis of the dialyzed proteins removed at weekly intervals showed an increasing loss of lysine, arginine and histidine, consistent with the extensive protein cross-linking observed. Irradiation of the dialyzed samples with UVA light (1.0 kJ/cm 2 total illumination through a 338 nm cutoff filter) caused an increasing loss of tryptophan, an additional loss of histidine and the production of micromolar concentrations of hydrogen peroxide. No alteration in amino acid content and no photolytic effects were seen in proteins incubated without ascorbic acid in proteins incubated with glucose for 4 weeks. The rate of hydrogen peroxide formation was linear with each glycated sample with a maximum production of 25 nmol/mg protein illuminated. The possibility that the sensitizer activity was due to an ascorbate-induced oxidation of tryptophan was eliminated by the presence of a heavy metal ion chelator during the incubation and by showing equivalent effects with ascorbate-incubated ribonuclease A, which is devoid of tryptophan. The ascorbate-incubated samples displayed increasing absorbance at wavelengths above 300 nm and increasing fluorescence (340/430) as glycation proceeded. The spectra of the 4 week glycated proteins were identical to those obtained with a solubilized water-insoluble fraction from human lens, which is known to have UVA sensitizer activity. (Author)

  6. Ascorbic acid reduced mutagenicity at the HPRT locus in CHO cells against thermal neutron radiation

    International Nuclear Information System (INIS)

    Kinashi, Yuko; Sakurai, Yoshinori; Masunaga, Shinichiro; Suzuki, Minoru; Nagata, Kenji; Ono, Koji

    2004-01-01

    We investigated the biological effects of the long-lived radicals induced following neutron irradiation. It has been reported that radiation-induced long-lived radicals were scavenged by post-irradiation treatment of ascorbic acid (Koyama, 1998). We studied the effects of ascorbic acid acting as a long-lived radical scavenger on cell killing and mutagenicity in Chinese hamster ovary cells against thermal neutrons produced at the Kyoto University Research reactor. Ascorbic acid was added to cells 30 min after neutron irradiation and removed 150 min after irradiation. The biological end point of cell survival was measured by colony formation assay. The mutagenicity was measured by the mutant frequency in the HPRT locus. The post-irradiation treatment of ascorbic acid did not alter the cell killing effect of neutron radiation. However, the mutagenicity was decreased, especially when the cells were irradiated with boron. Our results suggested that ascorbic acid scavenged long-lived radicals effectively and caused apparent protective effects against mutagenicity of boron neutron capture therapy

  7. Further investigations on the role of ascorbic acid in stratum corneum lipid models after UV exposure.

    Science.gov (United States)

    Trommer, Hagen; Böttcher, Rolf; Huschka, Christoph; Wohlrab, Wolfgang; Neubert, Reinhard H H

    2005-08-01

    This study is the continuation of our research into vitamin C and its possible effects on human skin after topical administration. The effects of ascorbic acid, iron ions and UV irradiation on stratum corneum lipid models were investigated. The lipid models used were: a simple system (linolenic acid dispersion), a complex system (liposomes consisting of dipalmitoylphosphatidylcholine, cholesterol and linolenic acid) and complex systems with additionally incorporated ceramides (types III and IV). The lipid peroxidation was quantified by the thiobarbituric acid assay. A human adult low-calcium high-temperature (HaCaT) keratinocytes cell culture was used as a second in-vitro model. The amount of intracellular peroxides was determined by measuring the fluorescence intensity using the dihydrorhodamine 123 assay. Electron paramagnetic resonance spectroscopy was used to study the influence of ascorbic acid and iron ions on the signal intensity of 5-doxylstearic acid during UV exposure. Ascorbic acid showed prooxidative properties in the thiobarbituric acid assay whereas cell protection was measured in the HaCaT keratinocytes experiments. Electron paramagnetic resonance investigations revealed different extents of free radical production generated by iron ions, ascorbic acid and UV irradiation. In evaluating the results from this study new aspects of the mechanism of lipid damage caused by these three factors were suggested, transcending the simple redox behaviour of ascorbic acid.

  8. Oxidation in fish oil enriched mayonnaise : Ascorbic acid and low pH increase oxidative deterioration

    DEFF Research Database (Denmark)

    Jacobsen, Charlotte; Timm Heinrich, Maike; Meyer, Anne S.

    2001-01-01

    The effect of ascorbic acid (0-4000 ppm) and pH (3.8-6.2) on oxidation and levels of iron and copper in various fractions of mayonnaise enriched with 16% fish oil was investigated. Ascorbic acid induced release of iron from the assumed oil- water interface into the aqueous phase at all pH levels......, but this effect of ascorbic acid was strongest at low pH (pH 3.8- 4.2). Ascorbic acid generally promoted formation of volatile oxidation compounds and reduced the peroxide value in mayonnaises. Peroxide values and total volatiles generally increased with decreasing pH values, suggesting that low pH promoted...... oxidation. It is proposed that iron bridges between the egg yolk proteins low-density lipoproteins, lipovitellin, and phosvitin at the oil-water interface are broken at low pH values, whereby iron ions become accessible as oxidation initiators. In the presence of ascorbic acid, oxidation is further enhanced...

  9. [Characteristics of proteins synthesized by hydrogen-oxidizing microorganisms].

    Science.gov (United States)

    Volova, T G; Barashkov, V A

    2010-01-01

    The study was conducted to determine the biological value of proteins synthesized by hydrogen-oxidizing microorganisms--the hydrogen bacteria Alcaligenes eutrophus Z1 and Ralstonia eutropha B5786 and the CO-resistant strain of carboxydobacterium Seliberia carboxydohydrogena Z1062. Based on a number of significant parameters characterizing the biological value of a product, the proteins of hydrogen-oxidizing microorganisms have been found to occupy an intermediate position between traditional animal and plant proteins. The high total protein in biomass of these microorganisms, their complete amino acid content, and availability to proteolytic enzymes allow for us to consider these microorganisms as potential protein producers.

  10. Synthesis of ZnO nanorods-Au nanoparticles hybrids via in-situ plasma sputtering-assisted method for simultaneous electrochemical sensing of ascorbic acid and uric acid

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Chao [College of Life Information Science & Instrument Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Liu, Hongying, E-mail: liuhongying@hdu.edu.cn [College of Life Information Science & Instrument Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093 (China); Zhang, Dan; Yang, Chi [Department of Pharmacy, Nantong University, Nantong 226001 (China); Zhang, Mingzhen [College of Life Information Science & Instrument Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China)

    2016-05-05

    In this study, ZnO nanorods-Au nanoparticles (ZnO NRs-Au NPs) hybrids were prepared using an in-situ plasma sputtering-assisted method without any template. Characterization results from scanning electron microscopy, high-resolution transmission electron microscopy, and energy dispersive X-ray spectroscopy showed that Au NPs are highly dispersed and tightly anchored on the surface of ZnO NRs. The size and surface coverage of Au NPs were well controlled by plasma sputtering time. Moreover, the hybrids exhibited excellent electrocatalytic properties towards oxidation of ascorbic acid (AA) and uric acid (UA) due to large surface area of Au NPs and ZnO NRs, and thus can be used as electrochemical sensors. Differential pulse voltammetry results showed that AA and UA could be detected simultaneously by ZnO NRs-Au NPs hybrids modified glassy carbon electrode. The linear ranges for AA and UA are 0.1 to 4 mM and 0.01 to 0.4 mM, respectively. The results suggest promising future applications in clinical diagnosis. - Highlights: • ZnO nanorods-Au nanoparticles were synthesized by in-situ plasma sputtering method. • Influence of sputtering time on the formation of Au nanoparticles was studied. • It exhibited a strong electrocatalytic activity toward the oxidation of ascorbic acid and uric acid. • A portable and cheap approach for simultaneous detection of ascorbic acid and uric acid was developed.

  11. Synthesis of ZnO nanorods-Au nanoparticles hybrids via in-situ plasma sputtering-assisted method for simultaneous electrochemical sensing of ascorbic acid and uric acid

    International Nuclear Information System (INIS)

    Hou, Chao; Liu, Hongying; Zhang, Dan; Yang, Chi; Zhang, Mingzhen

    2016-01-01

    In this study, ZnO nanorods-Au nanoparticles (ZnO NRs-Au NPs) hybrids were prepared using an in-situ plasma sputtering-assisted method without any template. Characterization results from scanning electron microscopy, high-resolution transmission electron microscopy, and energy dispersive X-ray spectroscopy showed that Au NPs are highly dispersed and tightly anchored on the surface of ZnO NRs. The size and surface coverage of Au NPs were well controlled by plasma sputtering time. Moreover, the hybrids exhibited excellent electrocatalytic properties towards oxidation of ascorbic acid (AA) and uric acid (UA) due to large surface area of Au NPs and ZnO NRs, and thus can be used as electrochemical sensors. Differential pulse voltammetry results showed that AA and UA could be detected simultaneously by ZnO NRs-Au NPs hybrids modified glassy carbon electrode. The linear ranges for AA and UA are 0.1 to 4 mM and 0.01 to 0.4 mM, respectively. The results suggest promising future applications in clinical diagnosis. - Highlights: • ZnO nanorods-Au nanoparticles were synthesized by in-situ plasma sputtering method. • Influence of sputtering time on the formation of Au nanoparticles was studied. • It exhibited a strong electrocatalytic activity toward the oxidation of ascorbic acid and uric acid. • A portable and cheap approach for simultaneous detection of ascorbic acid and uric acid was developed.

  12. Amperometric sensor for ascorbic acid based on a glassy carbon electrode modified with gold-silver bimetallic nanotubes in a chitosan matrix

    International Nuclear Information System (INIS)

    Yang, Penghao; Gao, Xia; Wang, Lisha; Wu, Qi; Chen, Zhichun; Lin, Xianfu

    2014-01-01

    We report on an amperometric sensor for ascorbic acid (AA) that is based on highly dense gold-silver nanotubes in a chitosan film on a glassy carbon electrode. The nanotubes were synthesized by a poly(vinyl pyrrolidone)-mediated polyol method employing a replacement reaction with silver nanowires as templates, and were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. Under the optimal conditions, the sensor exhibits good electrocatalytic activity towards the oxidation of AA, and this enables the determination of AA in the 5 μM to 2 mM concentration range, with a detection limit at 2 μM (at an S/N of 3). The response time is 2 s. The sensor displays good reproducibility, selectivity, sensitivity, and long-term stability. (author)

  13. Functionalized-graphene modified graphite electrode for the selective determination of dopamine in presence of uric acid and ascorbic acid.

    Science.gov (United States)

    Mallesha, Malledevaru; Manjunatha, Revanasiddappa; Nethravathi, C; Suresh, Gurukar Shivappa; Rajamathi, Michael; Melo, Jose Savio; Venkatesha, Thimmappa Venkatarangaiah

    2011-06-01

    Graphene is chemically synthesized by solvothermal reduction of colloidal dispersions of graphite oxide. Graphite electrode is modified with functionalized-graphene for electrochemical applications. Electrochemical characterization of functionalized-graphene modified graphite electrode (FGGE) is carried out by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The behavior of FGGE towards ascorbic acid (AA), dopamine (DA) and uric acid (UA) has been investigated by CV, differential pulse voltammetry (DPV) and chronoamperommetry (CA). The FGGE showed excellent catalytic activity towards electrochemical oxidation of AA, DA and UA compared to that of the bare graphite electrode. The electrochemical oxidation signals of AA, DA and UA are well separated into three distinct peaks with peak potential separation of 193mv, 172mv and 264mV between AA-DA, DA-UA and AA-UA respectively in CV studies and the corresponding peak potential separations in DPV mode are 204mv, 141mv and 345mv. The FGGE is successfully used for the simultaneous detection of AA, DA and UA in their ternary mixture and DA in serum and pharmaceutical samples. The excellent electrocatalytic behavior of FGGE may lead to new applications in electrochemical analysis. Copyright © 2011 Elsevier B.V. All rights reserved.

  14. A novel voltammetric sensor for ascorbic acid based on molecularly imprinted poly(o-phenylenediamine-co-o-aminophenol).

    Science.gov (United States)

    Kong, Yong; Shan, Xueling; Ma, Jianfeng; Chen, Meilan; Chen, Zhidong

    2014-01-27

    A molecularly imprinted copolymer, poly(o-phenylenediamine-co-o-aminophenol) (PoPDoAP), was prepared as a new ascorbic acid (AA) sensor. The copolymer was synthesized by incorporation of AA as template molecules during the electrochemical copolymerization of o-phenylenediamine and o-aminophenol, and complementary sites were formed after the copolymer was electrochemically reduced in ammonium aqueous solution. The molecularly imprinted copolymer sensor exhibited a high sensitivity and selectivity toward AA. Differential pulse voltammograms (DPVs) showed a linear concentration range of AA from 0.1 to 10 mM, and the detection limit was calculated to be 36.4 μM. Compared to conventional polyaniline-based AA sensors, the analytical performance of the imprinted copolymer sensor was improved due to the broadened usable pH range of PoPDoAP (from pH 1.0 to pH 8.0). The sensor also exhibited a good reproducibility and stability. And it has been successfully applied in the determination of AA in real samples, including vitamin C tablet and orange juices, with satisfactory results. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Effective ascorbate-free and photolatent click reactions in water using a photoreducible copper(II-ethylenediamine precatalyst

    Directory of Open Access Journals (Sweden)

    Redouane Beniazza

    2015-10-01

    Full Text Available The search for copper catalysts able to perform effectively click reactions in water in the absence of sodium ascorbate is an active area of current research with strong potential for applications in bioconjugation. The water-soluble and photoreducible copper(II–EDA (EDA = ethylenediamine complex 1, which has two 4-benzoylbenzoates acting as both counterion and photosensitizer, has been synthesized and characterized by different techniques including single crystal X-ray diffraction. Highly efficient photoreduction was demonstrated when solutions of 1 in hydrogen atom donating solvents, such as THF or MeOH, were exposed to UVA radiation (350–400 nm provided by a low pressure mercury lamp (type TLC = thin-layer chromatography, 365 nm, or by a 23 W fluorescent bulb, or by ambient/sunlight. In water, a much poorer hydrogen atom donating solvent, the photoreduction of 1 proved inefficient. Interestingly, EPR studies revealed that complex 1 could nonetheless be effectively photoreduced in water when alkynes were present in solution. The catalytic activity of 1 for click reactions involving a range of water-soluble alkynes and azides, in particular saccharides, was tested under various illumination conditions. Complex 1 was found to exhibit a photolatent character, the photogenerated copper(I being very reactive. On irradiating aqueous reaction mixtures containing 1 mol % of 1 at 365 nm (TLC lamp for 1 h, click reactions were shown to proceed to full conversion.

  16. Glucan synthesis in the genus Lactobacillus: Isolation and characterization of glucansucrase genes, enzymes and glucan products from six different strains

    NARCIS (Netherlands)

    Kralj, S.; Geel-Schutten, G.H. van; Dondorff, M.M.G.; Kirsanovs, S.; Maarel, M.J.E.C. van der; Dijkhuizen, L.

    2004-01-01

    Members of the genera Streptococcus and Leuconostoc synthesize various α-glucans (dextran, alternan and mutan). In Lactobacillus, until now, the only glucosyltransferase (GTF) enzyme that has been characterized is gtfA of Lactobacillus reuteri 121, the first GTF enzyme synthesizing a glucan

  17. Glucan synthesis in the genus Lactobacillus : isolation and characterization of glucansucrase genes, enzymes and glucan products from six different strains

    NARCIS (Netherlands)

    Kralj, S.; Geel-Schutten, G.H. van; Dondorff, M.M.G.; Kirsanovs, S.; Maarel, M.J.E.C. van der; Dijkhuizen, L.

    2004-01-01

    Members of the genera Streptococcus and Leuconostoc synthesize various α-glucans (dextran, alternan and mutan). In Lactobacillus, until now, the only glucosyltransferase (GTF) enzyme that has been characterized is gtfA of Lactobacillus reuteri 121, the first GTF enzyme synthesizing a glucan

  18. Effects of Ascorbic Acid, Alpha-Tocopherol and Allopurinol on Ischemia-Reperfusion Injury in Rabbit Skeletal Muscle: An Experimental Study

    Directory of Open Access Journals (Sweden)

    Bilgehan Erkut

    2007-01-01

    Full Text Available Purpose Ischemia reperfusion injury to skeletal muscle, following an acute arterial occlusion is important cause of morbidity and mortality. The aim of the present study was to determine and evaluate the effects of ascorbic acide, alpha-tocopherol and allopurinol on ischemia reperfusion injury in rabbit skeletal muscle. Methods Forty-eight New Zealand white rabbits, all male, weighing between 2.5 to 3.0 (mean 2.8 kg, were used in the study. They were separated into four groups. Group I was the control group without any drugs. The other groups were treatment groups (groups II, III, and IV. Group II rabbits administrated 50 mg/kg ascorbic acide and 100 mg/kg alpha-tocopherol 3 days prior to ischemia, group III rabbits received 50 mg/kg allopurinol 2 days prior to ischemia, and group IV rabbits were administrated both 50 mg/kg ascorbic acide, 100 mg/kg alpha-tocopherol 3 days prior to ischemia and 50 mg/kg allopurinol 2 days prior to ischemia. Two hours ischemia and 2 hours reperfusion were underwent to the treatment groups. At the end of the reperfusion periods, muscle samples were taken from rectus femoris muscle for determination of superoxide dismutase, catalase and glutathione peroxidase activities as antioxidant enzymes, and malondialdehyde as an indicator of lipid peroxidation and xanthine oxidase levels as source hydroxyl radical. Besides, histopathological changes (edema, inflammation, ring formation and splitting formation were evaluated in the muscle specimens. Results In the treatment groups; superoxide dismutase (U/mgprotein, catalase (U/mgprotein, and glutathione peroxidase (U/mgprotein levels increased, malondialdehyde (nmol/mgprotein and xanthine oksidase (mU/mgprotein levels decreased compared to control I ( p < 0.05. Increase of superoxide dismutase, catalase, and glutathione peroxidase levels were the highest and decrease of malondialdehyde and xanthine oxidase levels were the highest in group IV compared to groups II and III

  19. Effects of Ascorbic Acid, Alpha-Tocopherol and Allopurinol on Ischemia-Reperfusion Injury in Rabbit Skeletal Muscle: An Experimental Study

    Directory of Open Access Journals (Sweden)

    Bilgehan Erkut

    2007-01-01

    Full Text Available Purpose: Ischemia reperfusion injury to skeletal muscle, following an acute arterial occlusion is important cause of morbidity and mortality. The aim of the present study was to determine and evaluate the effects of ascorbic acide, alpha-tocopherol and allopurinol on ischemia reperfusion injury in rabbit skeletal muscle.Methods: Forty-eight New Zealand white rabbits, all male, weighing between 2.5 to 3.0 (mean 2.8 kg, were used in the study. They were separated into four groups. Group I was the control group without any drugs. The other groups were treatment groups (groups II, III, and IV. Group II rabbits administrated 50 mg/kg ascorbic acide and 100 mg/kg alpha-tocopherol 3 days prior to ischemia, group III rabbits received 50 mg/kg allopurinol 2 days prior to ischemia, and group IV rabbits were administrated both 50 mg/kg ascorbic acide, 100 mg/kg alpha-tocopherol 3 days prior to ischemia and 50 mg/kg allopurinol 2 days prior to ischemia. Two hours ischemia and 2 hours reperfusion were underwent to the treatment groups. At the end of the reperfusion periods, muscle samples were taken from rectus femoris muscle for determination of superoxide dismutase, catalase and glutathione peroxidase activities as antioxidant enzymes, and malondialdehyde as an indicator of lipid peroxidation and xanthine oxidase levels as source hydroxyl radical. Besides, histopathological changes (edema, inflammation, ring formation and splitting formation were evaluated in the muscle specimens. Results: In the treatment groups; superoxide dismutase (U/mgprotein, catalase (U/mgprotein, and glutathione peroxidise (U/mgprotein levels increased, malondialdehyde (nmol/mgprotein and xanthine oksidase (mU/mgprotein levels decreased compared to control I (p < 0.05. Increase of superoxide dismutase, catalase, and glutathione peroxidase levels were the highest and decrease of malondialdehyde and xanthine oxidase levels were the highest in group IV compared to groups II and III

  20. Synthesis of ascorbic acid enhanced TiO2 photocatalyst: its characterization and catalytic activity in CO2 photoreduction

    Directory of Open Access Journals (Sweden)

    Mohd Farid Bin Mohd Na'aim

    2018-04-01

    Full Text Available To date, the development of solar environmental remediation has shifted more emphasis on the green and simple synthesis of catalyst for CO2 photocatalysis process. Herein, TiO2 photocatalyst was successfully synthesized via hydrothermal method. The effects of the different molar ratio of ascorbic acid C6H8O6, (AA added during the preparation of TiO2 nanoparticles were comprehensively studied. The characterization of TiO2 nanocrystals was performed via XRD, XPS, DRUV-vis, and FTIR. The results show the AA loading into TiO2 nanoparticles significantly intensified the XRD spectra of anatase structure. In fact, this feature had signified a reactivity of the photocatalyst in the visible region. In an instance, BET surface area was also enhanced with the highest recorded value of 135.14 m2/g for 0.8AA. Meanwhile, the CO2 photoreduction over synthesized TiO2 had produced the highest amount of HCOOH at 39.3 μmol/g cat for 0.8AA within 6 hours of reaction time. Furthermore, the DRUV-vis analysis had illustrated better light absorption ability of 0.8AA. This profound finding is attributed to the correlation between large surface area, pure anatase phase, and high adsorbed water molecules. Therefore, this study had significantly demonstrated the potential of modified TiO2 with AA in CO2 photocatalysis area while simultaneously presents a green and simple method for TiO2 synthesis.

  1. Direct electrodeposition of gold nanotube arrays of rough and porous wall by cyclic voltammetry and its applications of simultaneous determination of ascorbic acid and uric acid

    International Nuclear Information System (INIS)

    Yang Guangming; Li Ling; Jiang Jinhe; Yang Yunhui

    2012-01-01

    Gold nanotube arrays of rough and porous wall has been synthesized by direct electrodeposition with cyclic voltammetry utilizing anodic aluminum oxide template (AAO) and polycarbonate membrane (PC) during short time (only 3 min and 2 min, respectively). The mechanism of the direct electrodeposition of gold nanotube arrays by cyclic voltammetry (CV) has been discussed. The morphological characterizations of the gold nanotube arrays have been investigated by scanning electron microscopy (SEM). A simultaneous determination of ascorbic acid (AA) and uric acid (UA) by differential pulse voltammetry (DPV) was constructed by attaching gold nanotube arrays (using AAO) onto the surface of a glassy carbon electrode (GCE). The electrochemical behavior of AA and UA at this modified electrode has been studied by CV and differential pulse voltammetry (DPV). The sensor offers an excellent response for AA and UA and the linear response range for AA and UA were 1.02 × 10 −7 –5.23 × 10 −4 mol L −1 and 1.43 × 10 −7 –4.64 × 10 −4 mol L −1 , the detection limits were 1.12 × 10 −8 mol L −1 and 2.24 × 10 −8 mol L −1 , respectively. This sensor shows good regeneration, stability and selectivity and has been used for the determination of AA and UA in real human urine and serum samples with satisfied results. - Graphical abstract: The schematic diagram of formation of Au nanotube arrays (a) and the stepwise procedure of the sensor (b). Highlights: ► Gold nanotubes array has been synthesized by cyclic voltammetry. ► The mechanism of deposition of gold nanotube has been discussed. ► A determination of ascorbic acid and uric acid was constructed by gold array. ► A satisfied determination of samples can be obtained by this sensor.

  2. Ascorbate availability affects tumor implantation-take rate and increases tumor rejection in Gulo–/– mice

    Directory of Open Access Journals (Sweden)

    Campbell EJ

    2016-04-01

    Full Text Available Elizabeth J Campbell,1 Margreet CM Vissers,2 Gabi U Dachs1 1Mackenzie Cancer Research Group, 2Centre for Free Radical Research, Department of Pathology, University of Otago, Christchurch, New Zealand Abstract: In solid tumors, HIF1 upregulates the expression of hundreds of genes involved in cell survival, tumor growth, and adaptation to the hypoxic microenvironment. HIF1 stabilization and activity are suppressed by prolyl and asparagine hydroxylases, which require oxygen as a substrate and ascorbate as a cofactor. This has led us to hypothesize that intracellular ascorbate availability could modify the hypoxic HIF1 response and influence tumor growth. In this study, we investigated the effect of variable intracellular ascorbate levels on HIF1 induction in cancer cells in vitro, and on tumor-take rate and growth in the Gulo–/– mouse. These mice depend on dietary ascorbate, and were supplemented with 3,300 mg/L, 330 mg/L, or 33 mg/L ascorbate in their drinking water, resulting in saturating, medium, or low plasma and tissue ascorbate levels, respectively. In Lewis lung carcinoma cells (LL/2 in culture, optimal ascorbate supplementation reduced HIF1 accumulation under physiological but not pathological hypoxia. LL/2, B16-F10 melanoma, or CMT-93 colorectal cancer cells were implanted subcutaneously into Gulo–/– mice at a range of cell inocula. Establishment of B16-F10 tumors in mice supplemented with 3,300 mg/L ascorbate required an increased number of cancer cells to initiate tumor growth compared with the number of cells required in mice on suboptimal ascorbate intake. Elevated ascorbate intake was also associated with decreased tumor ascorbate levels and a reduction in HIF1α expression and transcriptional activity. Following initial growth, all CMT-93 tumors regressed spontaneously, but mice supplemented with 33 mg/L ascorbate had lower plasma ascorbate levels and grew larger tumors than optimally supplemented mice. The data from this

  3. Sequence determination of synthesized chondroitin sulfate dodecasaccharides.

    Science.gov (United States)

    Shioiri, Tatsumasa; Tsuchimoto, Jun; Watanabe, Hideto; Sugiura, Nobuo

    2016-06-01

    Chondroitin sulfate (CS) is a linear acidic polysaccharide composed of repeating disaccharide units of glucuronic acid and N-acetyl-d-galactosamine. The polysaccharide is modified with sulfate groups at different positions by a variety of sulfotransferases. CS chains exhibit various biological and pathological functions by interacting with cytokines and growth factors and regulating their signal transduction. The fine structure of the CS chain defines its specific biological roles. However, structural analysis of CS has been restricted to disaccharide analysis, hampering the understanding of the structure-function relationship of CS chains. Here, we chemo-enzymatically synthesized CS dodecasaccharides having various sulfate modifications using a bioreactor system of bacterial chondroitin polymerase mutants and various CS sulfotransferases. We developed a sequencing method for CS chains using the CS dodecasaccharides. The method consists of (i) labeling a reducing end with 2-aminopyridine (PA), (ii) partial digestion of CS with testicular hyaluronidase, followed by separation of PA-conjugated oligosaccharides with different chain lengths, (iii) limited digestion of these oligosaccharides with chondroitin lyase AC II into disaccharides, followed by labeling with 2-aminobenzamide, (iv) CS disaccharide analysis using a dual-fluorescence HPLC system (reversed-phase ion-pair and ion-exchange chromatography), and (v) estimation of the composition by calculating individual disaccharide ratios. This CS chain sequencing allows characterization of CS-modifying enzymes and provides a useful tool toward understanding the structure-function relationship of CS chains. © The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. Effect of irradiation and cooking methods on ascorbic acid levels of four potato cultivars

    International Nuclear Information System (INIS)

    Shirsat, S.G.; Thomas, Paul

    1998-01-01

    The changes in reduced and total ascorbic acid (AA) contents in control and in tubers irradiated to 100 Gy gamma rays for sprout inhibition were studied by HPLC and iodophenol titrimetry methods in four potato cultivars as a function of storage at 15 degC and after cooking by different methods. Both reduced and total ascorbic acid levels decreased in control tubers during the first 3 months in storage recording respectively 22 to 35% and 26 to 45% losses depending on the cultivar. Irradiated tubers recorded additional losses of 5 to 10% and 6.5 to 13%, respectively in reduced and total ascorbic acid levels during the same period but remained in good marketable conditions. Cooking of tubers in boiling water showed maximum loss in vitamin C content, whereas pressure and microwave cooking recorded least losses. The magnitude of losses in reduced and total vitamin C during cooking was comparable in control and in irradiated tubers. (author)

  5. Ascorbic acid protects lipids in human plasma and low-density lipoprotein against oxidative damage

    Energy Technology Data Exchange (ETDEWEB)

    Frei, B. (Department of Nutrition, Harvard School of Public Health, Boston, MA (Unites States))

    1991-12-01

    The authors exposed human blood plasma and low-density lipoprotein (LDL) to many different oxidative challenges and followed the temporal consumption of endogenous antioxidants in relation to the initiation of oxidative damage. Under all types of oxidizing conditions, ascorbic acid completely protects lipids in plasma and LDL against detectable peroxidative damage as assessed by a specific and highly sensitive assay for lipid peroxidation. Ascorbic acid proved to be superior to the other water-soluble plasma antioxidants bilirubin, uric acid, and protein thiols as well as to the lipoprotein-associated antioxidants alpha-tocopherol, ubiquinol-10, lycopene, and beta-carotene. Although these antioxidants can lower the rate of detectable lipid peroxidation, they are not able to prevent its initiation. Only ascorbic acid is reactive enough to effectively intercept oxidants in the aqueous phase before they can attack and cause detectable oxidative damage to lipids.

  6. Ascorbic acid deficiency stimulates hepatic expression of inflammatory chemokine, cytokine-induced neutrophil chemoattractant-1, in scurvy-prone ODS rats.

    Science.gov (United States)

    Horio, Fumihiko; Kiyama, Keiichiro; Kobayashi, Misato; Kawai, Kaori; Tsuda, Takanori

    2006-02-01

    ODS rat has a hereditary defect in ascorbic acid biosynthesis and is a useful animal model for elucidating the physiological role of ascorbic acid. We previously demonstrated by using ODS rats that ascorbic acid deficiency changes the hepatic gene expression of acute phase proteins, as seen in acute inflammation. In this study, we investigated the effects of ascorbic acid deficiency on the production of inflammatory chemokine, cytokine-induced neutrophil chemoattractant-1 (CINC-1), in ODS rats. Male ODS rats (6 wk of age) were fed a basal diet containing ascorbic acid (300 mg/kg diet) or a diet without ascorbic acid for 14 d. Obvious symptoms of scurvy were not observed in the ascorbic acid-deficient rats. Ascorbic acid deficiency significantly elevated the serum concentration of CINC-1 on d 14. The liver and spleen CINC-1 concentrations in the ascorbic acid-deficient rats were significantly elevated to 600% and 180% of the respective values in the control rats. However, the lung concentration of CINC-1 was not affected by ascorbic acid deficiency. Ascorbic acid deficiency significantly elevated the hepatic mRNA level of CINC-1 (to 480% of the value in the control rats), but not the lung mRNA level. These results demonstrate that ascorbic acid deficiency elevates the serum, liver and spleen concentrations of CINC-1 as seen in acute inflammation, and suggest that ascorbic acid deficiency stimulate the hepatic CINC-1 gene expression.

  7. Polymeric nanoparticle of copper(II)-4,4′-dicyanamidobiphenyl ligand: Synthetic, spectral and structural aspect; application to electrochemical sensing of dopamine and ascorbic acid

    Energy Technology Data Exchange (ETDEWEB)

    Chiniforoshan, Hossein, E-mail: Chinif@cc.iut.ac.ir [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Ensafi, Ali A. [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Heydari-Bafrooei, Esmaeil [Department of Chemistry, Faculty of Science, Vali-e-Asr University of Rafsanjan, P.O. Box 518, Rafsanjan (Iran, Islamic Republic of); Khalesi, Sara Bahmanpour; Tabrizi, Leila [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2015-08-30

    Graphical abstract: - Highlights: • The polymer [Cu(bp)(H{sub 2}O){sub 2}]{sub n} synthesized and characterized. • The polymer was used as a modifier for the electrochemical determination of dopamine (DA) and ascorbic acid (AA). - Abstract: In this research, new polymer of 4,4′-dicyanamidobiphenyl (bpH{sub 2})-Cu(II) complex, [Cu(bp)(H{sub 2}O){sub 2}]{sub n}, has been synthesized and characterized by FT-IR, UV–vis spectroscopy and elemental analysis. The spherical morphology of Cu nanoparticles was confirmed by scanning electron microscopy (SEM) image and the transmission electron microscopy (TEM) image showed that the particle size dimensions of Cu nanoparticles were about 80 nm. Thermal gravimetric analysis (TGA) results indicated that this polymer was thermally stable. Hence, the prepared polymer was used as a modifier for the electrochemical determination of dopamine (DA) and ascorbic acid (AA). Compared to the bare carbon paste electrode (CPE) and multiwall carbon paste electrode (CNTPE), bpCu modified CPE (bpCu-CPE) exhibits much higher electrocatalytic activities toward the oxidation of dopamine and ascorbic acid with an increase in peak currents and a decrease in oxidation overpotentials. The effects of scan rate, concentration and pH were also studied. Differential pulse voltammetry results show that DA and AA could be detected selectively and sensitively at bpCu-CPE with peak-to-peak separation of 200 mV. Relative standard deviations for AA and DA determinations were less than 2.5%, and the linear response ranges of the electrode were 0.05–30.0 μmol L{sup −1} for AA and DA, respectively. The calculated detection limits were 0.02 and 0.04 μmol L{sup −1} (S/N = 3) for AA and DA, respectively. In addition, the presented method was successfully applied for the simultaneous determination of DA and AA in urine and blood samples with reliable recovery.

  8. Effect of short-term intravenous ascorbic acid on reducing ferritin in hemodialysis patients.

    Science.gov (United States)

    Jalalzadeh, M; Shekari, E; Mirzamohammadi, F; Ghadiani, M H

    2012-05-01

    Resistance to recombinant erythropoietin (rEPO) in hemodialysis patients may be due to inadequate iron recruitment and defect in iron use. In this cross over randomized clinical trial, 30 hemodialysis patients with serum ferritin levels of ≥500 ng/ml, hemoglobin ≤11.0 g/dl, and transferrin saturation (TSAT) of 20% or less were administrated intravenous iron (50-100 mg/wk) and rEPO (120-360 U/kg/wk) for 6 months. Patients were excluded if there was a clear explanation for rEPO hyporesponsiveness. Patients were divided into two groups. Group1 received standard care and 500 mg of intravenous ascorbic acid (IVAA) with each dialysis session in the first week of each month for a total of 3 months. Group 2 received standard care only. After 2 month washout period, groups were crossed over. Each month hemoglobin (Hb) was assessed. Iron, TIBC (transferrin iron binding capacity), TSAT, iPTH (intact parathyroid hormone), liver enzymes, albumin and cholesterol levels were measured every 3 months. After 3 months of intervention, Hb significantly increased from 10.11 to 12.19 g/dl (P <0 0.001; 95% confidence interval [CI] 2.7-1.4) and TSAT increased from 18.9 to 28.1% (P = 0.008; 95% CI 0.09-3), while ferritin and serum iron declined significantly from 1391 to 938 ng/ml (P = 0.001; 95% CI 216-689), 97.2 to 64.6 (P = 0.001; 95% CI 14.8-50.4) in the study group. Change of Hb over time in IVAA group was significant (P < 0.0005). There were significant differences between two groups in change of Hb level over time (P < 0.0005) and treatment effect (P = 0.002). Baseline laboratory tests were similar in the two groups and there was no carry over effect at phase 2. We showed that low amount of IVAA could reduce ferritin level and enhance Hb and TSAT, suggesting improved iron utilization.

  9. Factors that affect leaf extracellular ascorbic acid content and redox status

    Energy Technology Data Exchange (ETDEWEB)

    Burkey, K.O.; Fiscus, E.L. [North Carolina State Univ., United States dept. og Agriculture-Agricultural Research Service and Dept. of Crop Science, Raleigh, NC (United States); Eason, G. [North Carolina, State Univ., United States Dept. of Plant Pathology, Raleigh, NC (United States)

    2003-01-01

    Leaf ascorbic acid content and redox status were compared in ozone-tolerant (Provider) and ozone-sensitive (S156) genotypes of snap bean (Phaseolus vulgaris L.). Plants were grown in pots for 24 days under charcoal-filtered air (CF) conditions in open-top field chambers and then maintained as CF controls (29 nmol mol{sup 1} ozone) or exposed to elevated ozone (71 nmol mol{sup 1} ozone). Following a 10-day treatment, mature leaves of the same age were harvested early in the morning (06:00-08:00 h) or in the afternoon (13:00-15:00 h) for analysis of ascorbic acid (AA) and dehydroascorbic acid (DHA). Vacuum infiltration methods were used to separate leaf AA into apoplast and symplast fractions. The total ascorbate content [AA + DHA] of leaf tissue averaged 28% higher in Provider relative to S156, and Provider exhibited a greater capacity to maintain [AA + DHA] content under ozone stress. Apoplast [AA + DHA] content was 2-fold higher in tolerant Provider (360 nmol g{sup 1} FW maximum) relative to sensitive S156 (160 nmol g1 FW maximum) regardless of sampling period or treatment, supporting the hypothesis that extracellular AA is a factor in ozone tolerance. Apoplast [AA + DHA] levels were significantly higher in the afternoon than early morning for both genotypes, evidence for short-term regulation of extracellular ascorbate content. Total leaf ascorbate was primarily reduced with AA/[AA + DHA] ratios of 0.81-0.90. In contrast, apoplast AA/[AA + DHA] ratios were 0.01-0.60 and depended on genotype and ozone treatment. Provider exhibited a greater capacity to maintain extracellular AA/[AA + DHA] ratios under ozone stress, suggesting that ozone tolerance is associated with apoplast ascorbate redox status. (au)

  10. The Use of Ascorbic Acid as a Food Additive: Technical-Legal Issues

    Science.gov (United States)

    Varvara, Michele; Bozzo, Giancarlo; Celano, Giuseppe; Disanto, Chiara; Pagliarone, Cosimo Nicola

    2016-01-01

    Ascorbic acid (C6H8O6) is an organic compound belonging to the family of monosaccharide. It is highly soluble in water, and is often called one of the secrets of the Mediterranean diet. Its use is widespread in the food industry is also important, having always been exploited for its antioxidant and stabilising ability. Many indeed are the additive formulations that take advantage of these properties. The purpose of this paper is to explain the characteristics that make ascorbic acid an important food additive and to emphasise the technical and legal issues related to its use in food productions. In particular, in the course of this employment, laws and scientific studies have been applied to the resolution of a lawsuit, having as its object the use of ascorbic acid in preparations of ground beef sold at a butcher shop. The views expressed in court by the technical consultant have led to the acquittal of the accused, in the light of the demonstrated and proven non-toxicity of the molecule and the use of a mixture of additives for the production of sausage. The European and national legislations, supported by numerous scientific studies, define the possible use of ascorbic acid according to the principle of quantum satis, and it can be used in foods for children. Our work aims to represent further evidence of the safety of use of ascorbic acid as a food additive, and – as confirmed by the legal decision reported – it wants to bring out the prospects for use of ascorbic acid for technological purposes even by registered establishments. PMID:27800425

  11. Protective role of ascorbic acid in the decontamination of cow milk casein by gamma-irradiation.

    Science.gov (United States)

    Kouass Sahbani, Saloua; Klarskov, Klaus; Aloui, Amine; Kouass, Salah; Landoulsi, Ahmed

    2013-06-01

    The aim of this work was to investigate the protective role of ascorbic acid on irradiation-induced modification of casein. Casein stock solutions were irradiated with increasing doses 2-10 kGy using (60)Co Gamma rays at a dose rate D• = 136.73 Gy/min at room temperature. The total viable microorganism content of cow milk casein was evaluated by Plate Count Agar (PCA) incubation for 48 h at 37°C. Sodium dodecylsulfate gel electrophoresis (SDS-PAGE) and Matrix-Assisted Laser Desorption-Ionization Time-of-Flight mass spectrometry (MALDI-TOF-MS) analysis were used to evaluate the effect of gamma irradiation on casein integrity. Gamma irradiation reduced the bacterial contamination of casein solutions at a lower irradiation dose when performed in the presence of ascorbic acid. The irradiation treatment of casein in the absence of ascorbic acid with a dose of 4 kGy could reduce 99% of the original amount of bacterial colonies. However, in the presence of ascorbic acid the irradiation treatment of casein with a dose lower than 2 kGy could reduce 99% of the original amount of bacterial colonies which suggested that the irradiation dose lower than 2 kGy achieved almost the entire decontamination result. SDS-PAGE and MALDI-TOF-MS analysis showed that ascorbic acid protected cow milk casein from degradation and subsequent aggregation probably by scavenging oxygen and protein radicals produced by the irradiation. It is demonstrated that the combination of gamma irradiation and ascorbic acid produce additive effects, providing acceptable hygienic quality of cow milk casein and protects caseins against Reactive Oxygen Species (ROS) generated, during the irradiation process.

  12. The comparison of techniques and methods for L-ascorbic acid determination in the fruits

    Directory of Open Access Journals (Sweden)

    Cvetković Biljana R.

    2012-01-01

    Full Text Available Vitamin C is an essential vitamin for human nutrition; with the L-ascorbic acid (AA being the active form of vitamin C. Hence, determination of the L-ascorbic acid in the natural and processed foods is very important. In the past, plenty of methods based on the reversible redox reaction of AA oxidation/DHA reduction were developed. Because of L-ascorbic acid instability in aqueous solutions, it is useful to analyze various types of extraction. The aim of this study is to compare three different methods and three different extractants for the L-ascorbic acid determination. Fruits (kiwi, lemon, orange, and grapefruit were purchased from a local market. The L-ascorbic acid in these four samples was determined by the three different methods: the AOAC, the HPLC method with three different types of extractions, and the colorimetric method using ascorbate-oxidase. For the HPLC measurements, one part of the fruits was extracted with distilled water, the second with potassium hydrogen phosphate, and the third with 3% meta-phosphoric acid (MPA in 8% acetic acid. The HPLC measurements of each sample were repeated three times, the AOAC titration was repeated five times, and in the calorimetric method three measurements were performed. The results were statistically evaluated related to sample basis. Statistical analysis shows that there is a significant difference between the results for all three methods of extraction for all samples, except for the grapefruit sample where no significant difference was observed between the results obtained after the buffer extraction (E2 and the metaphosphoric acid in acetic acid extraction (E3. Discriminative analysis for the HPLC determinations proves that there is a clear difference and defined border between the samples in relation to the methods of extraction during the HPLC determination.

  13. Effect of Ascorbic Acid on Noise Induced Hearing Loss in Rats

    Directory of Open Access Journals (Sweden)

    Ziba Loukzadeh

    2015-07-01

    Full Text Available Introduction: After presbycusis, noise-induced hearing loss is the second most common cause of acquired hearing loss. Numerous studies have shown that high-intensity noise exposure increases free radical species; therefore, use of antioxidants to detoxify the free radicals can prevent cellular damage in the cochlea. We studied the potential hearing protective effect of different doses of ascorbic acid administered prior to noise exposure in rats.   Materials and Methods: Twenty-four male albino Wistar rats were randomly allocated into four groups: groups A, B, and C received 1250, 250, and 50 mg/kg/day of ascorbic acid, respectively, and group D acted as the control group. After 14 days of ascorbic acid administration, the rats were exposed to noise (105 dB sound pressure level for 2 h. Distortion product otoacoustic emissions (DPOAE were recorded prior to starting the ascorbic acid as baseline and 1 h after the noise exposure.   Results: The amplitude decrease was 14.99 dB for group A, 16.11 dB for group B, 28.82 dB for group C, and 29.91 dB for the control group. Moderate and high doses of ascorbic acid significantly reduced the transient threshold shift in the rats.   Conclusion:  The results of present study support the concept of cochlea protection by antioxidant agents. This dose-dependent protective effect was shown through the use of ascorbic acid treatment prior to noise exposure.

  14. Tear ascorbic acid levels and the total antioxidant status in contact lens wearers: A pilot study

    Directory of Open Access Journals (Sweden)

    Venkata Sai

    2009-01-01

    Full Text Available Aims: The tear ascorbate owing to its high concentration, functions as an effective antioxidant against the oxidative damage of cornea. Contact lens wearers (CLW are prone to oxidative stress due to the lens-induced hypoxic conditions. A pilot study was done to compare the tear ascorbic acid level and the total antioxidant capacity give as in normal and CLW. Materials and Methods: In this study 21 CLW (Mean age 23 ± 3 years ; M-2, F-19, who were daily wear users, with duration of wear not more than four years, along with age-matched 28 controls (Mean age 28 ± 3 ; M-15, F-13 were recruited in the study for collection of reflex tears using Schirmer′s strip. Ascorbic acid in tears was determined using high-performance liquid chromatography (HPLC, total antioxidant capacity (TAC and total protein assay by spectrophotometric analysis. Results: CLW showed no significant change in the tear ascorbic acid levels (0.4 ± 0.26 mM compared to the control subjects (0.61 ± 0.59 mM. The amount of ascorbic acid in tears did not correlate with the TAC or the total protein of the tears. The mean TAC in CLW was 0.69 ± 0.16 mM, with a total protein of 1.35 ± 0.46 mg/ml while in controls it was 0.7 ± 0.18 mM and 1.21 ± 0.47 mg/ml respectively . Conclusions: Soft contact lens wear did not show any significant change in tear ascorbic acid, TAC and total protein levels compared to controls.

  15. The synthesis of Au@C@Pt core-double shell nanocomposite and its application in enzyme-free hydrogen peroxide sensing

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yayun; Li, Yuhui; Jiang, Yingying [College of Chemistry & Environment, Minnan Normal University, Zhangzhou 363000 (China); Li, Yancai, E-mail: liyancai@mnnu.edu.cn [College of Chemistry & Environment, Minnan Normal University, Zhangzhou 363000 (China); Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Minnan Normal University, Zhangzhou 363000 (China); Li, Shunxing [College of Chemistry & Environment, Minnan Normal University, Zhangzhou 363000 (China); Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Minnan Normal University, Zhangzhou 363000 (China)

    2016-08-15

    Highlights: • A novel Au@C@Pt core-double shell nanocomposite was synthesized and characterized by SEM(*), TEM and EDS, etc. • The synthesized Au@C@Pt core-double shell nanocomposite showed high sensitivity and selectivity to electrocatalytic reduction of hydrogen peroxide (H{sub 2}O{sub 2}) and can be used to fabricate enzyme-free H{sub 2}O{sub 2} electrochemical sensor. • The H{sub 2}O{sub 2} sensor has two linear range of 9.0 μM–1.86 mM and 1.86 mM–7.11 mM, respectively, with a low limit of detection of 0.13 μM. • The H{sub 2}O{sub 2} sensor also displays high anti-interference ability, good stability and reproducibility. - Abstract: A novel Au@C@Pt core-double shell nanocomposite was synthesized and used to fabricate enzyme-free electrochemical sensor for rapid and sensitive detection of hydrogen peroxide (H{sub 2}O{sub 2}). The well-designed Au@C@Pt core-double shell nanocomposite was characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM) and energy-dispersed spectrum (EDS). The Au@C@Pt core-double shell nanocomposite modified glassy carbon electrode (Au@C@Pt/GCE) exhibits good electrocatalytic activity towards H{sub 2}O{sub 2} reduction at 0.0 V and can be used as H{sub 2}O{sub 2} sensor. The sensor displays two wide linear ranges towards H{sub 2}O{sub 2} detection. The one is 9.0 μM–1.86 mM with high sensitivity of 144.7 μA mM{sup −1} cm{sup −2}, and the other is 1.86 mM–7.11 mM with sensitivity of 80.1 μA mM{sup −1} cm{sup −2}. When signal to noise (S/N) is 3, the calculated detection limit (LOD) is 0.13 μM. Furthermore, the interference from the common interfering species such as glucose, ascorbic acid, dopamine and uric acid can be effectively avoided to H{sub 2}O{sub 2} detection. Additionally, the H{sub 2}O{sub 2} sensor also displays good stability and reproducibility.

  16. Arsenic induced toxicity in broiler chicks and its alleviation with ascorbic acid: a toxico-patho-biochemical study

    Science.gov (United States)

    Khan, Ahrar; Sharaf, Rabia; Khan, Muhammad Zargham; Saleemi, Muhammad Kashif; Mahmood, Fazal

    2013-01-01

    To find out toxico-pathological effects of arsenic (As) and ameliorating effect of ascorbic acid (Vit C), broilers birds were administered 50 and 250 mg/kg arsenic and Vit C, respectively alone/in combination. As-treated birds exhibited severe signs of toxicity such as dullness, depression, increased thirst, open mouth breathing and watery diarrhea. All these signs were partially ameliorated with the treatment of Vit C. As-treated birds showed a significant decrease in serum total proteins while serum enzymes, urea and creatinine were significantly increased. Alkaline phosphatase and lactate dehydrogenase completely whereas proteins, aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea and creatinine were partial ameliorated in birds treated with As+Vit C as compared to As-treated and control birds. Pale and hemorrhagic liver and swollen kidneys were observed in As-treated birds. Histopathologically, liver exhibited congestion and cytoplasmic vacuolation while in kidneys, condensation of tubular epithelium nuclei, epithelial necrosis, increased urinary spaces, sloughing of tubules from basement membrane and cast deposition were observed in As-treated birds. Pathological lesions were partially ameliorated with the treatment of Vit C. It can be concluded that arsenic induces biochemical and histopathological alterations in broiler birds; however, these toxic effects can be partially attenuated by Vit C.

  17. Tumor cells have decreased ability to metabolize H2O2: Implications for pharmacological ascorbate in cancer therapy

    Directory of Open Access Journals (Sweden)

    Claire M. Doskey

    2016-12-01

    Full Text Available Ascorbate (AscH− functions as a versatile reducing agent. At pharmacological doses (P-AscH−; [plasma AscH−] ≥≈20 mM, achievable through intravenous delivery, oxidation of P-AscH− can produce a high flux of H2O2 in tumors. Catalase is the major enzyme for detoxifying high concentrations of H2O2. We hypothesize that sensitivity of tumor cells to P-AscH− compared to normal cells is due to their lower capacity to metabolize H2O2. Rate constants for removal of H2O2 (kcell and catalase activities were determined for 15 tumor and 10 normal cell lines of various tissue types. A differential in the capacity of cells to remove H2O2 was revealed, with the average kcell for normal cells being twice that of tumor cells. The ED50 (50% clonogenic survival of P-AscH− correlated directly with kcell and catalase activity. Catalase activity could present a promising indicator of which tumors may respond to P-AscH−.

  18. Point-of-service, quantitative analysis of ascorbic acid in aqueous humor for evaluating anterior globe integrity

    Science.gov (United States)

    Gartia, Manas R.; Misra, Santosh K.; Ye, Mao; Schwartz-Duval, Aaron; Plucinski, Lisa; Zhou, Xiangfei; Kellner, David; Labriola, Leanne T.; Pan, Dipanjan

    2015-11-01

    Limited training, high cost, and low equipment mobility leads to inaccuracies in decision making and is concerning with serious ocular injuries such as suspected ruptured globe or post-operative infections. Here, we present a novel point-of-service (POS) quantitative ascorbic acid (AA) assay with use of the OcuCheck Biosensor. The present work describes the development and clinical testing of the paper-based biosensor that measures the changes in electrical resistance of the enzyme-plated interdigitated electrodes to quantify the level of AA present in ocular fluid. We have demonstrated the proof-of-concept of the biosensor testing 16 clinical samples collected from aqueous humor of patients undergoing therapeutic anterior chamber paracentesis. Comparing with gold standard colorimetric assay for AA concentration, OcuCheck showed accuracy of >80%, sensitivity of >88% and specificity of >71%. At present, there are no FDA-approved POS tests that can directly measures AA concentration levels in ocular fluid. We envisage that the device can be realized as a handheld, battery powered instrument that will have high impact on glaucoma care and point-of-care diagnostics of penetrating ocular globe injuries.

  19. Enzymes for improved biomass conversion

    Science.gov (United States)

    Brunecky, Roman; Himmel, Michael E.

    2016-02-02

    Disclosed herein are enzymes and combinations of the enzymes useful for the hydrolysis of cellulose and the conversion of biomass. Methods of degrading cellulose and biomass using enzymes and cocktails of enzymes are also disclosed.

  20. Cloning and Functional Analysis of the Promoter of an Ascorbate Oxidase Gene from Gossypium hirsutum

    OpenAIRE

    Xin, Shan; Tao, Chengcheng; Li, Hongbin

    2016-01-01

    Apoplastic ascorbate oxidase (AO) plays significant roles in plant cell growth. However, the mechanism of underlying the transcriptional regulation of AO in Gossypium hirsutum remains unclear. Here, we obtained a 1,920-bp promoter sequence from the Gossypium hirsutum ascorbate oxidase (GhAO1) gene, and this GhAO1 promoter included a number of known cis-elements. Promoter activity analysis in overexpressing pGhAO1::GFP-GUS tobacco (Nicotiana benthamiana) showed that the GhAO1 promoter exhibite...

  1. Kinetics and mechanism of reduction of cerium(IV) by ascorbic acid

    International Nuclear Information System (INIS)

    Bhatt, K.; Nand, K.C.

    1979-01-01

    The reduction of cerium(IV) has been studied in sulfuric acid medium using ascorbic acid as the reductant. The rate is found to be function of both Ce(IV) and AH 2 concentrations. Sulfuric acid retards the rate and the inverse order with respect to sulfuric acid is unity. The addition of chloride, bisulfate and sulfate of sodium show negative salt effect and an increase in the dielectric constant of the medium shows an accelerating effect on the reaction rate. Arrhenius parameters have been evaluated. A mechanism involving intermediate formation of ascorbate radical (AH) is proposed and the derived rate law agrees well with the experimental observations. (author)

  2. Relevance of DNA repair pathways on ascorbic acid effects on Echerichia Coli K-12 cells

    International Nuclear Information System (INIS)

    Slyus, M.A. van; Oliveira, R.L.B. da C.; Felzenszwalb, I.; Gomes, R.A.; Menck, C.F.

    1985-01-01

    Inactivation kinetics were performed with repair proficient and deficient Escherichia coli K-12 cells treated with oxidized solutions of ascorbic acid. The repair pathways controlled by the recA and uvrA gene products are essential for cell survival to the treatment. However, SOS chromotest result indicates that the SOS functions are only induced at high and toxic concentrations of the drug. Moreover, single strand breaks in DNA from treated cells are detected, demonstrating genome damage promoted by oxidized solutions of ascorbate. (M.A.C.) [pt

  3. Immobilized enzymes and cells

    Energy Technology Data Exchange (ETDEWEB)

    Bucke, C; Wiseman, A

    1981-04-04

    This article reviews the current state of the art of enzyme and cell immobilization and suggests advances which might be made during the 1980's. Current uses of immobilized enzymes include the use of glucoamylase in the production of glucose syrups from starch and glucose isomerase in the production of high fructose corn syrup. Possibilities for future uses of immobilized enzymes and cells include the utilization of whey and the production of ethanol.

  4. Profiling the orphan enzymes

    Science.gov (United States)

    2014-01-01

    The emergence of Next Generation Sequencing generates an incredible amount of sequence and great potential for new enzyme discovery. Despite this huge amount of data and the profusion of bioinformatic methods for function prediction, a large part of known enzyme activities is still lacking an associated protein sequence. These particular activities are called “orphan enzymes”. The present review proposes an update of previous surveys on orphan enzymes by mining the current content of public databases. While the percentage of orphan enzyme activities has decreased from 38% to 22% in ten years, there are still more than 1,000 orphans among the 5,000 entries of the Enzyme Commission (EC) classification. Taking into account all the reactions present in metabolic databases, this proportion dramatically increases to reach nearly 50% of orphans and many of them are not associated to a known pathway. We extended our survey to “local orphan enzymes” that are activities which have no representative sequence in a given clade, but have at least one in organisms belonging to other clades. We observe an important bias in Archaea and find that in general more than 30% of the EC activities have incomplete sequence information in at least one superkingdom. To estimate if candidate proteins for local orphans could be retrieved by homology search, we applied a simple strategy based on the PRIAM software and noticed that candidates may be proposed for an important fraction of local orphan enzymes. Finally, by studying relation between protein domains and catalyzed activities, it appears that newly discovered enzymes are mostly associated with already known enzyme domains. Thus, the exploration of the promiscuity and the multifunctional aspect of known enzyme families may solve part of the orphan enzyme issue. We conclude this review with a presentation of recent initiatives in finding proteins for orphan enzymes and in extending the enzyme world by the discovery of new

  5. The browning kinetics of the non-enzymatic browning reaction in L-ascorbic acid/basic amino acid systems

    Directory of Open Access Journals (Sweden)

    Ai-Nong YU

    Full Text Available Abstract Under the conditions of weak basis and the reaction temperature range of 110-150 °C, lysine, arginine and histidine were reacted with L-ascorbic acid at equal amount for 30-150 min, respectively and the formation of browning products was monitored with UV–vis spectrometry. The kinetic characteristics of their non-enzymatic browning reaction were investigated. The study results indicated that the non-enzymatic browning reaction of these three amino acids with L-ascorbic acid to form browning products was zero-order reaction. The apparent activation energies for the formation of browning products from L-ascorbic acid/lysine, L-ascorbic acid/arginine and L-ascorbic acid/histidine systems were 54.94, 50.08 and 35.31kJ/mol. The activation energy data indicated the degree of effects of reaction temperature on non-enzymatic browning reaction. Within the temperature range of 110-150 °C, the reaction rate of L-ascorbic acid/lysine system was the fastest one, followed by that of the L-ascorbic acid/arginine system. The reaction rate of L-ascorbic acid/histidine system was the slowest one. Based on the observed kinetic data, the formation mechanisms of browning products were proposed.

  6. UlaR activates expression of the ula operon in Streptococcus pneumoniae in the presence of ascorbic acid

    NARCIS (Netherlands)

    Afzal, Muhammad; Shafeeq, Sulman; Henriques-Normark, Birgitta; Kuipers, Oscar P

    In this study, the regulatory mechanism of the ula (utilization of l-ascorbic acid) operon, putatively responsible for transport and utilization of ascorbic acid in Streptococcus pneumoniae strain D39, is studied. β-Galactosidase assay data demonstrate that expression of the ula operon is increased

  7. Uptake of ascorbic acid by freshly isolated cells and secretory granules from the intermediate lobe of ox hypophyses

    DEFF Research Database (Denmark)

    Zhou, A; Matsumoto, T; Farver, O

    1990-01-01

    Mechanically isolated cells from the intermediate lobe of ox hypophyses contained 40.6 +/- 3.7 nmol mg-1 protein (mean +/- SE, n = 5) of ascorbic acid. They accumulated radioactivity time dependently, on incubation with L-[14C]ascorbic acid in ionic medium dominated by NaCl. No definite saturation...

  8. Low brain ascorbic acid increases susceptibility to seizures in mouse models of decreased brain ascorbic acid transport and Alzheimer’s disease

    OpenAIRE

    Warner, Timothy A; Kang, Jing-Qiong; Kennard, John A; Harrison, Fiona E

    2014-01-01

    Seizures are a known co-occurring symptom of Alzheimer’s disease, and they can accelerate cognitive and neuropathological dysfunction. Sub-optimal vitamin C (ascorbic acid) deficiency, that is low levels that do not lead the sufferer to present with clinical signs of scurvy (e.g. lethargy, hemorrhage, hyperkeratosis), are easily obtainable with insufficient dietary intake, and may contribute to the oxidative stress environment of both Alzheimer’s disease and epilepsy. The purpose of this stud...

  9. Ferulic acid with ascorbic acid synergistically extenuates the mitochondrial dysfunction during beta-adrenergic catecholamine induced cardiotoxicity in rats.

    Science.gov (United States)

    Yogeeta, Surinder Kumar; Raghavendran, Hanumantha Rao Balaji; Gnanapragasam, Arunachalam; Subhashini, Rajakannu; Devaki, Thiruvengadam

    2006-10-27

    Disruption of mitochondria and free radical mediated tissue injury have been reported during cardiotoxicity induced by isoproterenol (ISO), a beta-adrenergic catecholamine. The present study was designed to investigate the effect of the combination of ferulic acid (FA) and ascorbic acid (AA) on the mitochondrial damage in ISO induced cardiotoxicity. Induction of rats with ISO (150 mg/kg b.wt., i.p.) for 2 days resulted in a significant decrease in the activities of respiratory chain enzymes (NADH dehydrogenase and cytochrome c-oxidase), tricarboxylic acid cycle enzymes (isocitrate dehydrogenase, succinate dehydrogenase, malate dehydrogenase, alpha-ketoglutarate dehydrogenase), mitochondrial antioxidants (GPx, GST, SOD, CAT, GSH), cytochromes (b, c, c1, aa3) and in the level of mitochondrial phospholipids. A marked elevation in mitochondrial lipid peroxidation, mitochondrial levels of cholesterol, triglycerides and free fatty acids were also observed in ISO intoxicated rats. Pre-co-treatment with the combination of FA (20 mg/kg b.wt.) and AA (80 mg/kg b.wt.) orally for 6 days significantly enhanced the attenuation of these functional abnormalities and restored normal mitochondrial function when compared to individual drug treated groups. Mitigation of ISO induced biochemical and morphological changes in mitochondria were more pronounced with a combination of FA and AA rather than the individual drug treated groups. Transmission electron microscopic observations also correlated with these biochemical parameters. Hence, these findings demonstrate the synergistic ameliorative potential of FA and AA on mitochondrial function during beta-adrenergic catecholamine induced cardiotoxicity and associated oxidative stress in rats.

  10. Effect of L-ascorbic acid on nickel-induced alterations in serum lipid profiles and liver histopathology in rats.

    Science.gov (United States)

    Das, Kusal K; Gupta, Amrita Das; Dhundasi, Salim A; Patil, Ashok M; Das, Swastika N; Ambekar, Jeevan G

    2006-01-01

    Nickel exposure greatly depletes intracellular ascorbate and alters ascorbate-cholesterol metabolism. We studied the effect of the simultaneous oral treatment with L-ascorbic acid (50 mg/100 g body weight (BW) and nickel sulfate (2.0 mg/100 g BW, i.p) on nickelinduced changes in serum lipid profiles and liver histopathology. Nickel-treated rats showed a significant increase in serum low-density lipoprotein-cholesterol, total cholesterol, triglycerides, and a significant decrease in serum high-density lipoprotein-cholesterol. In the liver, nickel sulfate caused a loss of normal architecture, fatty changes, extensive vacuolization in hepatocytes, eccentric nuclei, and Kupffer cell hypertrophy. Simultaneous administration of L-ascorbic acid with nickel sulfate improved both the lipid profile and liver impairments when compared with rats receiving nickel sulfate only. The results indicate that L-ascorbic acid is beneficial in preventing nickel-induced lipid alterations and hepatocellular damage.

  11. Brassinosteroid-induced CO{sub 2} assimilation is associated with increased stability of redox-sensitive photosynthetic enzymes in the chloroplasts in cucumber plants

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Yu Ping; Cheng, Fei; Zhou, Yan Hong; Xia, Xiao Jian; Mao, Wei Hua; Shi, Kai [Department of Horticulture, Zijingang Campus, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058 (China); Chen, Zhi Xiang [Department of Horticulture, Zijingang Campus, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058 (China); Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907-2054 (United States); Yu, Jing Quan, E-mail: jqyu@zju.edu.cn [Department of Horticulture, Zijingang Campus, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058 (China); Key Laboratory of Horticultural Plants Growth, Development and Quality Improvement, Ministry of Agriculture of China, Yuhangtang Road 866, Hangzhou 310058 (China)

    2012-09-28

    Highlights: Black-Right-Pointing-Pointer Activity of certain Calvin cycle enzymes and CO{sub 2} assimilation are induced by BRs. Black-Right-Pointing-Pointer BRs upregulate the activity of the ascorbate-glutathione cycle in the chloroplasts. Black-Right-Pointing-Pointer BRs increase the chloroplast thiol reduction state. Black-Right-Pointing-Pointer A BR-induced reducing environment increases the stability of photosynthetic enzymes. -- Abstract: Brassinosteroids (BRs) play important roles in plant growth, development, photosynthesis and stress tolerance; however, the mechanism underlying BR-enhanced photosynthesis is currently unclear. Here, we provide evidence that an increase in the BR level increased the quantum yield of PSII, activities of Rubisco activase (RCA) and fructose-1,6-bisphosphatase (FBPase), and CO{sub 2} assimilation. BRs upregulated the transcript levels of genes and activity of enzymes involved in the ascorbate-glutathione cycle in the chloroplasts, leading to an increased ratio of reduced (GSH) to oxidized (GSSG) glutathione in the chloroplasts. An increased GSH/GSSG ratio protected RCA from proteolytic digestion and increased the stability of redox-sensitive enzymes in the chloroplasts. These results strongly suggest that BRs are capable of regulating the glutathione redox state in the chloroplasts through the activation of the ascorbate-glutathione cycle. The resulting increase in the chloroplast thiol reduction state promotes CO{sub 2} assimilation, at least in part, by enhancing the stability and activity of redox-sensitive photosynthetic enzymes through post-translational modifications.

  12. Artificial Enzymes, "Chemzymes"

    DEFF Research Database (Denmark)

    Bjerre, Jeannette; Rousseau, Cyril Andre Raphaël; Pedersen, Lavinia Georgeta M

    2008-01-01

    Enzymes have fascinated scientists since their discovery and, over some decades, one aim in organic chemistry has been the creation of molecules that mimic the active sites of enzymes and promote catalysis. Nevertheless, even today, there are relatively few examples of enzyme models that successf......Enzymes have fascinated scientists since their discovery and, over some decades, one aim in organic chemistry has been the creation of molecules that mimic the active sites of enzymes and promote catalysis. Nevertheless, even today, there are relatively few examples of enzyme models...... that successfully perform Michaelis-Menten catalysis under enzymatic conditions (i.e., aqueous medium, neutral pH, ambient temperature) and for those that do, very high rate accelerations are seldomly seen. This review will provide a brief summary of the recent developments in artificial enzymes, so called...... "Chemzymes", based on cyclodextrins and other molecules. Only the chemzymes that have shown enzyme-like activity that has been quantified by different methods will be mentioned. This review will summarize the work done in the field of artificial glycosidases, oxidases, epoxidases, and esterases, as well...

  13. Magnetically responsive enzyme powders

    Energy Technology Data Exchange (ETDEWEB)

    Pospiskova, Kristyna, E-mail: kristyna.pospiskova@upol.cz [Regional Centre of Advanced Technologies and Materials, Palacky University, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Safarik, Ivo, E-mail: ivosaf@yahoo.com [Regional Centre of Advanced Technologies and Materials, Palacky University, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Department of Nanobiotechnology, Institute of Nanobiology and Structural Biology of GCRC, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic)

    2015-04-15

    Powdered enzymes were transformed into their insoluble magnetic derivatives retaining their catalytic activity. Enzyme powders (e.g., trypsin and lipase) were suspended in various liquid media not allowing their solubilization (e.g., saturated ammonium sulfate and highly concentrated polyethylene glycol solutions, ethanol, methanol, 2-propanol) and subsequently cross-linked with glutaraldehyde. Magnetic modification was successfully performed at low temperature in a freezer (−20 °C) using magnetic iron oxides nano- and microparticles prepared by microwave-assisted synthesis from ferrous sulfate. Magnetized cross-linked enzyme powders were stable at least for two months in water suspension without leakage of fixed magnetic particles. Operational stability of magnetically responsive enzymes during eight repeated reaction cycles was generally without loss of enzyme activity. Separation of magnetically modified cross-linked powdered enzymes from reaction mixtures was significantly simplified due to their magnetic properties. - Highlights: • Cross-linked enzyme powders were prepared in various liquid media. • Insoluble enzymes were magnetized using iron oxides particles. • Magnetic iron oxides particles were prepared by microwave-assisted synthesis. • Magnetic modification was performed under low (freezing) temperature. • Cross-linked powdered trypsin and lipase can be used repeatedly for reaction.

  14. Targeted enzyme prodrug therapies.

    Science.gov (United States)

    Schellmann, N; Deckert, P M; Bachran, D; Fuchs, H; Bachran, C

    2010-09-01

    The cure of cancer is still a formidable challenge in medical science. Long-known modalities including surgery, chemotherapy and radiotherapy are successful in a number of cases; however, invasive, metastasized and inaccessible tumors still pose an unresolved and ongoing problem. Targeted therapies designed to locate, detect and specifically kill tumor cells have been developed in the past three decades as an alternative to treat troublesome cancers. Most of these therapies are either based on antibody-dependent cellular cytotoxicity, targeted delivery of cytotoxic drugs or tumor site-specific activation of prodrugs. The latter is a two-step procedure. In the first step, a selected enzyme is accumulated in the tumor by guiding the enzyme or its gene to the neoplastic cells. In the second step, a harmless prodrug is applied and specifically converted by this enzyme into a cytotoxic drug only at the tumor site. A number of targeting systems, enzymes and prodrugs were investigated and improved since the concept was first envisioned in 1974. This review presents a concise overview on the history and latest developments in targeted therapies for cancer treatment. We cover the relevant technologies such as antibody-directed enzyme prodrug therapy (ADEPT), gene-directed enzyme prodrug therapy (GDEPT) as well as related therapies such as clostridial- (CDEPT) and polymer-directed enzyme prodrug therapy (PDEPT) with emphasis on prodrug-converting enzymes, prodrugs and drugs.

  15. Enzymes in Fermented Fish.

    Science.gov (United States)

    Giyatmi; Irianto, H E

    Fermented fish products are very popular particularly in Southeast Asian countries. These products have unique characteristics, especially in terms of aroma, flavor, and texture developing during fermentation process. Proteolytic enzymes have a main role in hydrolyzing protein into simpler compounds. Fermentation process of fish relies both on naturally occurring enzymes (in the muscle or the intestinal tract) as well as bacteria. Fermented fish products processed using the whole fish show a different characteristic compared to those prepared from headed and gutted fish. Endogenous enzymes like trypsin, chymotrypsin, elastase, and aminopeptidase are the most involved in the fermentation process. Muscle tissue enzymes like cathepsins, peptidases, transaminases, amidases, amino acid decarboxylases, glutamic dehydrogenases, and related enzymes may also play a role in fish fermentation. Due to the decreased bacterial number during fermentation, contribution of microbial enzymes to proteolysis may be expected prior to salting of fish. Commercial enzymes are supplemented during processing for specific purposes, such as quality improvement and process acceleration. In the case of fish sauce, efforts to accelerate fermentation process and to improve product quality have been studied by addition of enzymes such as papain, bromelain, trypsin, pepsin, and chymotrypsin. © 2017 Elsevier Inc. All rights reserved.

  16. Plasma ascorbic acid, a priori diet quality score, and incident hypertension

    NARCIS (Netherlands)

    Buijsse, Brian; Jacobs, D.R.; Steffen, L.M.; Kromhout, Daan; Gross, M.D.

    2015-01-01

    Vitamin C may reduce risk of hypertension, either in itself or by marking a healthy diet pattern. We assessed whether plasma ascorbic acid and the a priori diet quality score relate to incident hypertension and whether they explain each other's predictive abilities. Data were from 2884 black and

  17. A method for the determination of ascorbic acid using the iron(II)-pyridine-dimethylglyoxime complex

    Energy Technology Data Exchange (ETDEWEB)

    Arya, S. P.; Mahajan, M. [Haryana, Kurukshetra Univ. (India). Dept. of Chemistry

    1998-05-01

    A simple and rapid spectrophotometric method for the determination of ascorbic acid is proposed. Ascorbic acid reduces iron (III) to iron (II) which forms a red colored complex with dimethylglyoxime in the presence of pyridine. The absorbance of the resulting solution is measured at 514 nm and a linear relationship between absorbance and concentration of ascorbic acid is observed up to 14 {mu}g ml{sup -1}. Studies on the interference of substances usually associated with ascorbic acid have been carried out and the applicability of the method has been tested by analysing pharmaceutical preparations of vitamin C. [Italiano] Si propone un rapido e semplice metodo spettrofotometrico per la determinazione dell`acido ascorbico. L`acido ascorbico riduce il ferro(III) a ferro(II) che forma con la dimetilgliossima, in presenza di piridina, un complesso colorato in rosso. L`assorbanza della soluzione risultante e` misurata a 514 nm e si ottiene una relazione lineare tra assorbanza e concentrazione dell`acido ascorbico fino a 14 {mu}g ml{sup -1}. Si sono condotti studi sugli interferenti usualmente associati all`acido ascorbico ed e` stata valutata l`applicabilita` del metodo all`analisi di preparati farmaceutici di vitamina C.

  18. Investigation of L(+)-Ascorbic Acid with Raman Spectroscopy in Visible and UV Light

    DEFF Research Database (Denmark)

    Berg, Rolf W.

    2015-01-01

    Abstract: Raman spectroscopy investigations of l(+)-ascorbic acid and its mono- and di-deprotonated anions (AH(-) and A(2-)) are reviewed and new measurements reported with several wavelengths, 229, 244, 266, 488, and 532nm. Results are interpreted, assisted by new DFT/B3LYP quantum chemical calc......). Relatively weak preresonance enhancement was seen for A(2-) when excitation was done with 229nm UV light, allowing water bands to become observable as for normal visible light Raman spectra....... calculations with 6-311++G(d,p) basis sets for several conformations of ascorbic acid and the anions. Raman spectra were measured during titration with NaOH base in an oxygen-poor environment to avoid fluorescence when solutions were alkaline. The ultraviolet (UV) absorption band for ascorbic acid in aqueous......cm(-1). Finally, for the ascorbate di-anion, absorption was found at similar to 298.4nm with molar absorptivity of similar to 7,000 L mol(-1) cm(-1) and below similar to 220nm. With UV light (244 and 266nm), strongly basic solutions gave pronounced Raman resonance enhancement at similar to 1556cm(-1...

  19. Effects of Ascorbic Acid on Garlic-induced Alterations in Semen ...

    African Journals Online (AJOL)

    Effects of Ascorbic Acid on Garlic-induced Alterations in Semen Parameters Of Wistar Rats. GO Omotoso, IO Onanuga, AAG Jimoh. Abstract. No Abstract. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT · http://dx.doi.org/10.4314/tjhc.v18i2.69616 · AJOL African Journals ...

  20. Effects of supplemental vitamin C (Ascorbic Acid) on the growth and ...

    African Journals Online (AJOL)

    Four different diets each containing 37.4% crude protein were formulated from locally available feed materials to contain 0 (control), 23, 46 and 92 mg/Kg supplemental Ascorbic acid (AA) respectively. Catfish with average weight of 2 - 6g were stocked and fed twice daily to satiation initially with Coppens fish feed for the first ...

  1. A proposed relationship between pH and ascorbic acid content of ...

    African Journals Online (AJOL)

    A relationship between the ascorbic acid content of fresh squeezed juice of orange, lemon, grape and lime and the pH was presented. The relationship established were statistically compared with those obtained by the 2,6 dichlorophenol indophenol titration method. It was shown that they do not differ significantly (p≥0.05) ...

  2. The Effects of Various Levels of Ascorbic Acid Intake Upon Oral Wound Healing in Guinea Pigs.

    Science.gov (United States)

    1983-01-01

    Pauling, L.C.: Ascorbic Acid and Glycosaminoglycans. An Orthomolecular Approach to Cancer and Other Diseases. Oncology. 37: 181, 1973. .- . .. 92 2 13...Metabolism or Vitamin C. Medicine . 20s 251, 1941. 37. Abt. A.F., Von Schuching, S., and Roe, J.s. Connective Tissue Studies. I. Relation of Dietary and

  3. Effects of Ascorbic Acid and Reduced Glutathione on the Alleviation of Salinity Stress in Olive Plants

    NARCIS (Netherlands)

    Aliniaeifard, S.; Hajilou, J.; Tabatabaei, S.J.; Seifi Kalhor, Maryam

    2016-01-01

    The aim of this study was to evaluate the effects of low molecular mass antioxidants and NaCl salinity on growth, ionic balance, proline, and water contents of ‘Zard’ olive trees under controlled greenhouse conditions. The experiment was carried out by spraying 2 mM of ascorbic acid (Asc) and 3

  4. [Nickel exposure to A549 cell damage and L-ascorbic acid interference effect].

    Science.gov (United States)

    Fu, Yao; Wang, Yue; Dan, Han; Zhang, Lin; Ma, Wenhan; Pan, Yulin; Wu, Yonghui

    2015-05-01

    Studying different concentrations of nickel smelting smoke subjects of human lung adenocarcinoma cells (A549) carcinogenic effects, discusses the influence of L-ascorbic acid protection. The A549 cells were divided into experimental and L-ascorbic acid in the intervention group. Plus exposure group concentration of nickel refining dusts were formulated 0.00, 6.25, 12.50, 25.00, 50.00, 100.00 µg/ml suspension, the intervention group on the basis of the added exposure group containing L-ascorbic acid (100 mmol/L), contact 24 h. Detection of cell viability by MTT assay. When the test substance concentration select 0.00, 25.00, 50.00, 100.00 µg/ml experiment for internal Flou-3 fluorescent probe to detect cell Ca²⁺ concentration, within DCFH-DA detect intracellular reactive oxygen (ROS) content, real-time quantitative PCR (real time, in the RT-PCR) was used to detect cell HIF-1α gene expression. With the increase of concentration, subjects increased cell growth inhibition rate, intracellular Ca²⁺ concentration increases, ROS content increased, HIF-1α gene expression increased, differences were statistically significant (P nickel exposure damage to cells. With subjects following exposure to nickel concentration increased, its effect on A549 cell damage increases, L-ascorbic acid cell damage caused by nickel has certain protective effect.

  5. Neurobehavioural and Neurotoxic Effects of L-ascorbic Acid and L ...

    African Journals Online (AJOL)

    Background: Lead is an environmental toxicant, occupational and environmental exposures remain a serious problem in developing and industrializing countries. Objective: This study is designed to investigate the effects of L-ascorbic acid and L-tryptophan on the neurotoxicity and neurobehavioural alterations in lead ...

  6. Plasma Ascorbic Acid in Insulin and Non-insulin Dependent Diabetes

    African Journals Online (AJOL)

    Blood glucose, plasma ascorbic acid and haemoglobin levels were estimated in insulin dependent diabetics, non-insulin dependent diabetics and controls matched for number, sex and age. Significantly higher levels of these parameters were found in control group than in the other two groups. Statistically differences were ...

  7. Effect of Two-minute Application of 35% Sodium Ascorbate on Composite Bond Strength following Bleaching.

    Science.gov (United States)

    Ismail, Eman H; Kilinc, Evren; Hardigan, Patrick C; Rothrock, James K; Thompson, Jeffrey Y; Garcia-Godoy, Cristina

    2017-10-01

    The aim of this study is to assess the effect of 35% sodium ascorbate on microtensile bond strength of dentin immediately after bleaching with 35% hydrogen peroxide. A total of 25 sound human 3 rd molars were collected. Teeth were randomly divided into five groups for different treatments: Group I [bleaching + immediate bonding (i.e., restoration)], group II (bleaching + delayed bonding), group III (bleaching + sodium ascorbate + immediate bonding), group IV (bleaching + sodium ascorbate + delayed bonding), and group V (bonding only). After bleaching, but before bonding, groups II and IV were stored for 1 week in deionized water at 37°C. All samples were bonded using OptiBoned FL (Kerr) and Filtek Supreme (3M/ESPE). Teeth were sectioned into 1 × 1 mm 2 bars, and microtensile bond strength was tested with a universal testing machine (Instron 8841) at a cross-head speed of 0.5 mm/minute. Microtensile bond strength differed significantly across the five groups, with a significant reduction in microtensile bond strength observed for samples in group I relative to samples in any of the other treatment groups (p bleaching on composite bonding strength to dentin. The negative effects of bleaching on composite bonding can be neutralized by the application of the reversing agent sodium ascorbate thus, increasing the efficiency of clinic chair time. This is clinically relevant for those patients requiring restorative treatment immediately after in-office bleaching.

  8. Foliar application of ascorbic acid mitigates sodium chloride induced stress in eggplant (solanum melongena l.)

    International Nuclear Information System (INIS)

    Jan, S.; Hamayun, M.

    2016-01-01

    The current work was designed to test the effect of sodium chloride on germination, seedling establishment, vegetative growth, yield, chemical contents and ionic composition of eggplant. The consequences of foliar application of ascorbic acid (AA) on mitigation of adverse effects of sodium chloride were also tested. The seeds of Solanum melongena were germinated using NaCl (60 mM, 100 mM) and ascorbic acid (100 and 200 mM). High levels of salinity significantly affected the seed germination and seedling fresh and dry weights. Plants grown under salinity stress with foliar application of ascorbic acid showed significant increase in germination percentage and seedlings growth as compare to control plants. Sodium chloride stress showed adverse effects on plant height, root length, number of leaves, leaf area, fresh and dry biomass, total chlorophyll, carbohydrates and proteins as compared to untreated plants. The relative water content, electrolyte leakage were increased and Na+ and K+ ions balance was disturbed in different plant parts. Ascorbic acid (100 and 200ppm) enhanced all the growth parameters affected adversely by sodium chloride stress. (author)

  9. Reversal of clinical symptoms and radiographic abnormalities with protein restriction and ascorbic acid in alkaptonuria.

    NARCIS (Netherlands)

    Morava, E.; Kosztolanyi, G.Y.; Engelke, U.F.H.; Wevers, R.A.

    2003-01-01

    There is no definitive treatment protocol for alkaptonuria. A patient with alkaptonuria was treated with ascorbic acid (0.5 g/day) from the age of 4 years. He developed episodes of severe recurrent joint pain at 9.5 years of age after which a protein-restricted diet (1.3 g/kg/day) was started.

  10. Pyrophosphate levels strongly influence ascorbate and starch content in tomato fruit

    Directory of Open Access Journals (Sweden)

    Sonia eOsorio

    2013-08-01

    Full Text Available Ascorbate (vitamin C deficiency leads to low immunity, scurvy, and other human diseases and is therefore a global health problem. Given that plants are major ascorbate sources for humans, biofortification of this vitamin in our foodstuffs is of considerable importance. Ascorbate is synthetized by a number of alternative pathways: (i from the glycolytic intermediates D-glucose-6P (the key intermediates are GDP-D-mannose and L-galactose, (ii from the breakdown of the cell wall polymer pectin which uses the methyl ester of D-galacturonic acid as precursor and (iii from myo-inositol as precursor via myo-inositol oxygenase. We report here the engineering of fruit-specific overexpression of a bacterial pyrophosphatase, which hydrolyzes the inorganic pyrophosphate (PPi to orthophosphate (Pi. This strategy resulted in increased vitamin C levels up to 2.5 fold in ripe fruit as well as increasing in the major sugars, sucrose and glucose, yet decreasing the level of starch. When considered together, these finding indicate an intimate linkage between ascorbate and sugar biosynthesis in plants. Moreover, the combined data reveal the importance of PPi metabolism in tomato fruit metabolism and development.

  11. Stabilization of an injection preparation of technetium-99m MDP with ascorbic acid

    International Nuclear Information System (INIS)

    Lindelauf, F.M.P.; Sijtma, S.K.

    1983-01-01

    Tc-99m-labelled preparations for bone scanning are subject to oxidation in vitro. This results in bad scans with images of soft tissues as well. Three commercially available preparations were tested for stability after addition of ascorbic acid which effectively counteracts the oxidation by dissolved oxygen. (Auth.)

  12. Morphological assessment of bone mineralization in tibial metaphyses of ascorbic acid-deficient ODS rats.

    Science.gov (United States)

    Hasegawa, Tomoka; Li, Minqi; Hara, Kuniko; Sasaki, Muneteru; Tabata, Chihiro; de Freitas, Paulo Henrique Luiz; Hongo, Hiromi; Suzuki, Reiko; Kobayashi, Masatoshi; Inoue, Kiichiro; Yamamoto, Tsuneyuki; Oohata, Noboru; Oda, Kimimitsu; Akiyama, Yasuhiro; Amizuka, Norio

    2011-08-01

    Osteogenic disorder shionogi (ODS) rats carry a hereditary defect in ascorbic acid synthesis, mimicking human scurvy when fed with an ascorbic acid-deficient (aa-def) diet. As aa-def ODS rats were shown to feature disordered bone formation, we have examined the bone mineralization in this rat model. A fibrous tissue layer surrounding the trabeculae of tibial metaphyses was found in aa-def ODS rats, and this layer showed intense alkaline phosphatase activity and proliferating cell nuclear antigen-immunopositivity. Many osteoblasts detached from the bone surfaces and were characterized by round-shaped rough endoplasmic reticulum (rER), suggesting accumulation of malformed collagen inside the rER. Accordingly, fine, fragile fibrillar collagenous structures without evident striation were found in aa-def bones, which may result from misassembling of the triple helices of collagenous α-chains. Despite a marked reduction in bone formation, ascorbic acid deprivation seemed to have no effect on mineralization: while reduced in number, normal matrix vesicles and mineralized nodules could be seen in aa-def bones. Fine needle-like mineral crystals extended from these mineralized nodules, and were apparently bound to collagenous fibrillar structures. In summary, collagen mineralization seems unaffected by ascorbic acid deficiency in spite of the fine, fragile collagenous fibrils identified in the bones of our animal model.

  13. Functional role of ascorbic acid in bread-making | Dadzie-Mensah ...

    African Journals Online (AJOL)

    bread characteristics. Various levels of ascorbic acid and bromate were used in the bread production to compare critical functional properties of bread. The results showed that the specific volume of the loaves increased from 2.80 cm3/g ...

  14. The effect of ascorbic acid and propranolol on normal sleep and ...

    African Journals Online (AJOL)

    This study was designed to investigate the possible effects of ascorbic acid on open field locomotor activity and normal sleep in healthy adult rats and evaluate how these correlate with those of propranolol. MethodS: Eighty healthy adult Wistar rats of both sexes were divided into two groups of 40 animals each group.

  15. Effects of L-ascorbic acid and alpha-tocopherol on biochemical ...

    African Journals Online (AJOL)

    Background: The purpose of this study is to determine the effect of L-ascorbic acid and alpha-tocopherol as well as combination of these vitamins with or without exposure to physical exercise on intensity of lipid peroxidation, activity of xanthine oxidase, activity of total antioxidative system, concentration of glutathione, and ...

  16. The effects of ascorbic acid on salt induced alfalfa (Medicago sativa L.)

    African Journals Online (AJOL)

    Dr. J. T. Ekanem

    contribute to the high electrical conductivity of salt-affected lands3. ... the cellular mechanisms of the stress and its application at the .... Fig 2: Effect of salt and ascorbic acid on a) stem length, b) root length, c) root number, d) dry weight of ...

  17. Experience of application of ascorbate chitosan in the treatment of periodontal disease

    Directory of Open Access Journals (Sweden)

    Bulkina N.V.

    2013-09-01

    Full Text Available Aim. To study the clinical anti-inflammatory effect of gel form 8% ascorbate chitozan in treatment of inflammatory periodontal disease. Material and methods. The study included 30 patients: 10 patients with chronic catarrhal gingivitis, 10 patients with chronic generalized periodontitis mild and 10 moderate. Criteria for inclusion of patients in the study: age between 18 and 45 years old, reliable diagnosis, informed consent of the patient. Case history of the disease duration from one to five years. The state of periodontal tissue was evaluated clinically and radiographically by intraoral radiography. According to treatment methods patients were divided into groups: group 1 underwent traditional treatment, group 2 was treated with the use of applications of 8% of ascorbate chitosan on the area of papillae and marginal gingiva with the capture of 1-2 cm of the mucous membrane of the alveolar process. The duration of treatment was 15 minutes daily for 10 days. Results. The patterns suggest that the therapeutic effect of ascorbate chitazan caused prolonged sanation of periodontal pockets due to the antibacterial activity of chitazan. Conclusion. The data show that regeneration in patients who have a combined treatment included ascorbate chitosan has been more rapid and complete than similar processes in periodontal patients treated in a traditional way.

  18. Copper/ascorbic acid dyad as a catalytic system for selective aerobic oxidation of amines

    Czech Academy of Sciences Publication Activity Database

    Šrogl, Jiří; Voltrová, Svatava

    2009-01-01

    Roč. 11, č. 4 (2009), s. 843-845 ISSN 1523-7060 Institutional research plan: CEZ:AV0Z40550506 Keywords : copper * ascorbic acid * oxidative deamination Subject RIV: CC - Organic Chemistry Impact factor: 5.420, year: 2009

  19. Effect of Combined Intake of Garcinia Kola and Ascorbic Acid on ...

    African Journals Online (AJOL)

    This study was carried out to determine the effect of combined intake of Garcinia kola and Ascorbic acid on Intraocular pressure (IOP) of normotensive Nigerians. A total of one hundred and sixty (n= 160) parcipants, males, and females within the age range of 18-50 years (Mean age = 29.29± 8.74) were used for this study.

  20. Antinociceptive Properties of Ascorbic Acid: Evidence for the Mechanism of Action

    Directory of Open Access Journals (Sweden)

    Zeraati

    2014-09-01

    Full Text Available Background Ascorbic acid is amongst important water-soluble vitamins and when used orally in high-doses it has been observed to relieve pain and reduce opioid use in patients. However no controlled trial has compared the antinociceptive effects of ascorbic acid with other analgesic groups on animal models, and investigated the involved mechanisms. Objectives In the present study, the antinociceptive effect of vitamin C on male mice was investigated and compared with morphine and diclofenac. Also, possible mechanisms were assayed. Materials and Methods Male albino mice were used in this study. Antinociception was measured using the writhing test, tail flick and formalin tests. Ascorbic acid was used in three doses (30, 150 and 300 mg/kg, IP and compared with the antinociceptive effects of 10 mg/kg of morphine as an opioid analgesic agent and 5-10 mg/kg of diclofenac as a nonsteroidal anti-inflammatory drug (NSAID analgesic agent.The antinociceptive effect of ascorbic acid (300 mg/kg was compared before and after treatment with naloxone (4 mg/kg, ondansetron (0.5 mg/kg, atropine (5 mg/kg and metoclopramide (1 mg/kg in the writhing test. Results Vitamin C caused dose-dependent antinociceptive effects in acetic acid writhing test (P < 0.05. It had no significant effect in the tail flick test. Meanwhile, vitamin C in high doses reduced pain in the second phase of the formalin test (P < 0.05. Morphine had higher nociceptive effects in comparison to ascorbic acid in the writhing test (P < 0.05. In the second phase of the formalin test the antinociceptive effects of vitamin C (300 mg/kg was not significantly different with morphine at dose of 10 mg/kg. There was not significant difference between vitamin C (300 mg/kg and diclofenac (10 mg/kg in the second phase of the formalin test. Metoclopramide and ondansetrone reduced the antinociceptive effects of vitamin C. Conclusions The results obtained from the acetic acid induced writhing test and second

  1. Comparison of radioprotective effects of caffeine and ascorbic acid in male mice

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Kyu; Kim, Ji Hyang; Lee, Byoung Hun [KAERI, Taejon (Korea, Republic of); Yoon, Yong Dal [Hanyang Univ., Seoul (Korea, Republic of)

    2003-04-01

    The oxygen effect in radiation biology is well known. Since oxygen enhances radiation-induced biological damage, antioxidants should be radioprotectors. Ascorbic acid (vitamin C) or caffeine is an essential component in the diet of humans and a small range of other mammals. Radioprotective effects of vitamin C have been demonstrated in certain cells and animals, which would result from scavenging free radicals. Caffeine is the main psychoactive ingredient of coffee, tea, even coke with a high frequency of concurrent use in humans. Caffeine has been recently reported as a scavenger of hydroxyl radical in millimolar levels and a potently radioprotector in a chronically exposed rodent. This study investigates functional radioprotection of caffeine and ascorbic acid against gamma irradiation in male mice. Eight-week-old male C57BL/6N mice were irradiated with 6.5 Gy. A caffeine treated group was administered with 80 mg/kg body weight by i.p injection, a single exposure 1 hour before irradiation. Ascorbic acid was administered 330 mg/liter in drinking water through all the experimental period. The remaining mice were kept as sham controls. After collecting a serum from the experimental mice 6 hr after irradiation, qualitative analysis of testosterone was performed by means of radioimmunoassay (RIA). For histological investigation, testes were removed 1 week after irradiation and fixed in NBF. Fixed testes were processed for paraffin sections and stained by H-E. The circulating testosterone significantly decreased in all irradiated groups. The harmful effect of radiation on the body and organ weight and the appearance of semiferous tubules were significantly improved in the caffeine - or ascorbic acid-treated group. In conclusion, caffeine and ascorbic acid protected spermatogenesis from impairment against gamma radiation, acting as a radioprotector.

  2. Determination of ascorbic acid in pharmaceutical preparation and fruit juice using modified carbon paste electrode

    Directory of Open Access Journals (Sweden)

    Simona Žabčíková

    2016-06-01

    Full Text Available Acrobic acid is key substance in the human metabolism and the rapid and accurate determination in food is of a great interest. Ascorbic acid is an electroactive compound, however poorly responded on the bare carbon paste electrodes. In this paper, brilliant cresyl blue and multi-walled carbon nanotubes were used for the modification of carbon paste electrode. Brilliant cresyl blue acts as a mediator improving the transition of electrons, whereas multiwalled carbon nanotubes increased the surface of the electrode. Both brilliant cresyl blue and multiwalled carbon nanotubes were added directly to the composite material. The electrochemical behavior of modified electode was determined in electrolyte at various pH, and the effect of the scan rate was also performed. It was shown that the electrochemical process on the surface of the modified carbon paste electrode was diffusion-controlled. The resulted modified carbon paste electrode showed a good electrocatalytic activity towards the oxidation of ascorbic acid at a reduced overpotential of +100 mV descreasing the risk of interferences. A linear response of the ascorbic acid oxidation current measured by the amperometry in the range of 0.1 - 350 µmol.L-1 was obtained applying the sensor for the standard solution. The limit of detection and limit of quantification was found to be 0.05 and 0.15 µmol.L-1, respectively. The novel method was applied for the determination of ascorbic acid in pharmaceutical vitamin preparation and fruit juice, and the results were in good agreement with the standard HPLC method. The presented modification of carbon paste electrode is suitable for the fast, sensitive and very accurate determination of ascorbic acid in fruit juices and pharmaceutical preparation.

  3. Ascorbic acid supplementation diminishes microparticle elevations and neutrophil activation following SCUBA diving.

    Science.gov (United States)

    Yang, Ming; Barak, Otto F; Dujic, Zeljko; Madden, Dennis; Bhopale, Veena M; Bhullar, Jasjeet; Thom, Stephen R

    2015-08-15

    Predicated on evidence that diving-related microparticle generation is an oxidative stress response, this study investigated the role that oxygen plays in augmenting production of annexin V-positive microparticles associated with open-water SCUBA diving and whether elevations can be abrogated by ascorbic acid. Following a cross-over study design, 14 male subjects ingested placebo and 2-3 wk later ascorbic acid (2 g) daily for 6 days prior to performing either a 47-min dive to 18 m of sea water while breathing air (∼222 kPa N2/59 kPa O2) or breathing a mixture of 60% O2/balance N2 from a tight-fitting face mask at atmospheric pressure for 47 min (∼40 kPa N2/59 kPa O2). Within 30 min after the 18-m dive in the placebo group, neutrophil activation, and platelet-neutrophil interactions occurred, and the total number of microparticles, as well as subgroups bearing CD66b, CD41, CD31, CD142 proteins or nitrotyrosine, increased approximately twofold. No significant elevations occurred among divers after ingesting ascorbic acid, nor were elevations identified in either group after breathing 60% O2. Ascorbic acid had no significant effect on post-dive intravascular bubble production quantified by transthoracic echocardiography. We conclude that high-pressure nitrogen plays a key role in neutrophil and microparticle-associated changes with diving and that responses can be abrogated by dietary ascorbic acid supplementation. Copyright © 2015 the American Physiological Society.

  4. EFFECT OF PHYSICAL EXERCISE ON LIPID PEROXIDATION AND ANTIOXIDANT ASCORBIC ACID DEFENSE

    Directory of Open Access Journals (Sweden)

    Ljiljana M. Popović

    2006-06-01

    Full Text Available Strenuous exercises greatly increase oxygen consumption in the whole body, especially in skeletal muscles. Large part of oxygen consumption is reduced to H2O and ATP, but smaller part (2-5% results in an increased leakage of electrons from the mitochondrial respiratory chain, forming various reactive oxygen species ─ ROS (O2˙¯, H2O2 i OH˙. These free radicals are capable of triggering a chain of damaging biochemical and physiological reactions (oxidative stress, lipid peroxidation,as a base for skeletal muscles damage after exercise. MDA (malondialdehide is a marker of exercise induced lipid peroxidation process. L–ascorbic acid is a major aqueous-phase antioxidant. To estimate antioxidant role of ascorbic acid we use rate between dehidroascorbate and ascorbate. In this paper those markers were determinated in 30 students, in rest and after treadmill running protocol (Bruce Treadmill Protocol. It was found that after the treadmill test , plasma MDA level had increased from 3,04 to 4,39 μM/L. Plasma ascorbic acid was also found to be higher after the treadmill test comparing to rest level (from 55,4 to 67,6 μM/L. DHA/A level in rest was 1,62 and after treadmill test it increased to 2,05. These results suggests that strenuous exercise increased process of lipid peroxidation, but in the same time increased ascorbic acid level in plasma and DHA/A rate indicates stronger antioxidant defense system.

  5. Comparison of radioprotective effects of caffeine and ascorbic acid in male mice

    International Nuclear Information System (INIS)

    Kim, Jin Kyu; Kim, Ji Hyang; Lee, Byoung Hun; Yoon, Yong Dal

    2003-01-01

    The oxygen effect in radiation biology is well known. Since oxygen enhances radiation-induced biological damage, antioxidants should be radioprotectors. Ascorbic acid (vitamin C) or caffeine is an essential component in the diet of humans and a small range of other mammals. Radioprotective effects of vitamin C have been demonstrated in certain cells and animals, which would result from scavenging free radicals. Caffeine is the main psychoactive ingredient of coffee, tea, even coke with a high frequency of concurrent use in humans. Caffeine has been recently reported as a scavenger of hydroxyl radical in millimolar levels and a potently radioprotector in a chronically exposed rodent. This study investigates functional radioprotection of caffeine and ascorbic acid against gamma irradiation in male mice. Eight-week-old male C57BL/6N mice were irradiated with 6.5 Gy. A caffeine treated group was administered with 80 mg/kg body weight by i.p injection, a single exposure 1 hour before irradiation. Ascorbic acid was administered 330 mg/liter in drinking water through all the experimental period. The remaining mice were kept as sham controls. After collecting a serum from the experimental mice 6 hr after irradiation, qualitative analysis of testosterone was performed by means of radioimmunoassay (RIA). For histological investigation, testes were removed 1 week after irradiation and fixed in NBF. Fixed testes were processed for paraffin sections and stained by H-E. The circulating testosterone significantly decreased in all irradiated groups. The harmful effect of radiation on the body and organ weight and the appearance of semiferous tubules were significantly improved in the caffeine - or ascorbic acid-treated group. In conclusion, caffeine and ascorbic acid protected spermatogenesis from impairment against gamma radiation, acting as a radioprotector

  6. Key Building Blocks via Enzyme-Mediated Synthesis

    Science.gov (United States)

    Fischer, Thomas; Pietruszka, Jörg

    Biocatalytic approaches to valuable building blocks in organic synthesis have emerged as an important tool in the last few years. While first applications were mainly based on hydrolases, other enzyme classes such as oxidoreductases or lyases moved into the focus of research. Nowadays, a vast number of biotransformations can be found in the chemical and pharmaceutical industries delivering fine chemicals or drugs. The mild reaction conditions, high stereo-, regio-, and chemoselectivities, and the often shortened reaction pathways lead to economical and ecological advantages of enzymatic conversions. Due to the enormous number of enzyme-mediated syntheses, the present chapter is not meant to be a complete review, but to deliver comprehensive insights into well established enzymatic systems and recent advances in the application of enzymes in natural product synthesis. Furthermore, it is focused on the most frequently used enzymes or enzyme classes not covered elsewhere in the present volume.

  7. Perception of Paralinguistic Traits in Synthesized Voices

    DEFF Research Database (Denmark)

    Baird, Alice Emily; Hasse Jørgensen, Stina; Parada-Cabaleiro, Emilia

    2017-01-01

    Along with the rise of artificial intelligence and the internet-of-things, synthesized voices are now common in daily–life, providing us with guidance, assistance, and even companionship. From formant to concatenative synthesis, the synthesized voice continues to be defined by the same traits we...

  8. Composites comprising biologically-synthesized nanomaterials

    Science.gov (United States)

    Curran, Seamus; Dias, Sampath; Blau, Werner; Wang, Jun; Oremland, Ronald S; Baesman, Shaun

    2013-04-30

    The present disclosure describes composite materials containing a polymer material and a nanoscale material dispersed in the polymer material. The nanoscale materials may be biologically synthesized, such as tellurium nanorods synthesized by Bacillus selenitireducens. Composite materials of the present disclosure may have optical limiting properties and find use in optical limiting devices.

  9. Effects of Pre-Converted Nitrite from Red Beet and Ascorbic Acid on Quality Characteristics in Meat Emulsions

    Science.gov (United States)

    Kim, Hyun-Wook; Hwang, Ko-Eun

    2017-01-01

    We investigated the effects of fermented red beet extract and ascorbic acid on color development in meat emulsions. The pH of meat emulsions containing red beet extract decreased with an increase in the amount of extract added. The redness of the treated meat emulsions was higher than that of the control with no added nitrite or fermented red beet extract (pmeat emulsions treated with fermented red beet extract only was lower than in that treated with both fermented red beet extract and ascorbic acid (pmeat emulsions treated with fermented red beet extract were higher than in that treated with both fermented red beet extract and ascorbic acid (pmeat emulsions tested. Treatment T2, containing nitrite and ascorbic acid, had the highest overall acceptability score (pnitrite from red beet extract and 0.05% ascorbic acid (p>0.05). The residual nitrite content of the meat emulsions treated with ascorbic acid was lower than in those treated without ascorbic acid (pnitrite for the stability of color development in meat emulsions. PMID:28515652

  10. Ascorbic acid levels in human tears after photorefractive keratectomy, transepithelial photorefractive keratectomy, and laser in situ keratomileusis.

    Science.gov (United States)

    Bilgihan, A; Bilgihan, K; Toklu, Y; Konuk, O; Yis, O; Hasanreisoğlu, B

    2001-04-01

    To investigate the level of ascorbic acid in human tear fluid after photorefractive keratectomy (PRK), transepithelial PRK, and laser in situ keratomileusis (LASIK). Departments of Ophthalmology and Biochemistry, School of Medicine, Gazi University, Ankara, Turkey. Twenty patients (7 women and 13 men) were included in this study. Traditional PRK with epithelial scraping by a blunt spatula followed by surface ablation (7 eyes), transepithelial PRK (7 eyes), or LASIK (6 eyes) was performed. Tears were collected preoperatively and 1 and 5 days postoperatively. Ascorbic acid levels were measured using 2-4 dinitrophenylhydrazine. Ascorbic acid levels in the tear fluid were decreased significantly 1 day after PRK, transepithelial PRK, and LASIK (P <.05). On the fifth day, the ascorbic acid levels were significantly lower than preoperatively in all groups. After PRK, transepithelial PRK, and LASIK, the ascorbic acid levels of the tear fluid decreased significantly. Because ascorbic acid is the major scavenger of superoxide radicals in tears, topical ascorbic acid therapy may help eliminate the harmful effect of free radicals from excimer laser surgery.

  11. EFFECT OF ASCORBIC ACID ON THE RIGHT AND LEFT CORONARY ARTERIES OF MALE RABBITS FED WITH HIGH-CHOLESTEROL DIET

    Directory of Open Access Journals (Sweden)

    Gholamreza Dashti

    2010-12-01

    Full Text Available   Abstract INTRODUCTION: Atherosclerosis and cardiovascular diseases are the most common causes of death in western countries. The beneficial effect of ascorbic acid on various organs has been reported. The present study was conducted to determine the effect of ascorbic acid on the right and left coronary arteries of male rabbits fed with high-cholesterol diet. methods: Twenty white male rabbits (mean weight: 950 g were weighed and randomly divided into two groups. For 40 days, group 1 (n=10 was given a high-cholesterol (1% diet, group 2 (n=10 was fed with a high-cholesterol diet and ascorbic acid (100 mg/kg. Then both of the groups were weighed and the animals were sacrificed. The right and left coronary arteries were dissected and then fixation, tissue processing, histological sectioning and H & E staining were carried out and sections were studied by light microscopy. The results were analyzed by using the Mann Whitney test. results: Group 2 which received ascorbic acid had no fatty streaks in their coronary arteries. Significant difference in mean weight was observed before and after the diet in both groups (P<0.05. CONCLUSIONS: Histopathological study of the coronary arteries showed that the rabbits which received ascorbic acid diet did not develop fatty streaks. Thus ascorbic acid exerts an apparently inhibitory effect on fatty streak formation and may slow down or prevent atherosclerosis by countering the side effects of a high-fat meal.     Keywords: Ascorbic acid, cholesterol, coronary arteries.

  12. KONJAC1 and 2 Are Key Factors for GDP-Mannose Generation and Affect l-Ascorbic Acid and Glucomannan Biosynthesis in Arabidopsis

    Energy Technology Data Exchange (ETDEWEB)

    Sawake, Shota [Saitama Univ. (Japan); Tajima, Noriaki [Saitama Univ. (Japan); Mortimer, Jenny C. [Univ. of Cambridge (United Kingdom); RIKEN Center for Sustainable Resource Science, Yokohama (Japan); Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Lao, Jeemeng [Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Ishikawa, Toshiki [Saitama Univ. (Japan); Yu, Xiaolan [Univ. of Cambridge (United Kingdom); Yamanashi, Yukiko [Saitama Univ. (Japan); Yoshimi, Yoshihisa [Saitama Univ. (Japan); Kawai-Yamada, Maki [Saitama Univ. (Japan); Dupree, Paul [Saitama Univ. (Japan); Tsumuraya, Yoichi [Saitama Univ. (Japan); Kotake, Toshihisa [Saitama Univ. (Japan); Univ. of Cambridge (United Kingdom)

    2015-12-01

    Humans are unable to synthesize L-ascorbic acid (AsA), yet it is required as a cofactor in many critical biochemical reactions. The majority of human dietary AsA is obtained from plants. In Arabidopsis thaliana, a GDP-mannose pyrophosphorylase (GMPP), VITAMIN C DEFECTIVE1 (VTC1), catalyzes a rate-limiting step in AsA synthesis: the formation of GDP-Man. In this study, we identified two nucleotide sugar pyrophosphorylase-like proteins, KONJAC1 (KJC1) and KJC2, which stimulate the activity of VTC1. The kjc1kjc2 double mutant exhibited severe dwarfism, indicating that KJC proteins are important for growth and development. The kjc1 mutation reduced GMPP activity to 10% of wild-type levels, leading to a 60% reduction in AsA levels. On the contrary, overexpression of KJC1 significantly increased GMPP activity. The kjc1 and kjc1kjc2 mutants also exhibited significantly reduced levels of glucomannan, which is also synthesized from GDP-Man. Recombinant KJC1 and KJC2 enhanced the GMPP activity of recombinant VTC1 in vitro, while KJCs did not show GMPP activity. Yeast two-hybrid assays suggested that the stimulation of GMPP activity occurs via interaction of KJCs with VTC1. These results suggest that KJCs are key factors for the generation of GDP-Man and affect AsA level and glucomannan accumulation through the stimulation of VTC1 GMPP activity.

  13. Enzymic lactose hydrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Miller, J J; Brand, J C

    1980-01-01

    Acid or enzymic hydrolysis can be used to hydrolyze lactose. Advantages of both are compared and details of enzymic hydrolysis using yeast or fungal enzymes given. The new scheme outlined involves recycling lactase. Because lactose and lactase react to ultrafiltration (UF) membranes differently separation is possible. Milk or milk products are ultrafiltered to separate a concentrate from a lactose-rich permeate which is treated with lactase in a reactor until hydrolysis reaches a required level. The lactase can be removed by UF as it does not permeate the membrane, and it is recycled back to the reactor. Permeate from the second UF stage may or may not be recombined with the concentrate from the first stage to produce a low lactose product (analysis of a typical low-lactose dried whole milk is given). Batch or continuous processes are explained and a batch process without enzyme recovery is discussed. (Refs. 4).

  14. Indicators: Sediment Enzymes

    Science.gov (United States)

    Sediment enzymes are proteins that are produced by microorganisms living in the sediment or soil. They are indicators of key ecosystem processes and can help determine which nutrients are affecting the biological community of a waterbody.

  15. Enzyme Vs. Extremozyme -32 ...

    Indian Academy of Sciences (India)

    Enzymes are biocatalytic protein molecules that enhance the rates of ... to physical forces (hydrogen bonds, hydrophobic 1, electrostatic and Van der ... conformation. In 1995 ... surface against 14.7% in Klenow poll (some of the hydrophobic.

  16. Ascorbic acid as a bifunctional hydrogen bond donor for the synthesis of cyclic carbonates from CO2 under ambient conditions

    KAUST Repository

    Arayachukiat, Sunatda

    2017-07-14

    Readily available ascorbic acid was discovered as an environmentally benign hydrogen bond donor (HBD) for the synthe-sis of cyclic organic carbonates from CO2 and epoxides in the presence of nucleophilic co-catalysts. The ascorbic acid/TBAI (TBAI: tetrabutylammonium iodide) binary system could be applied for the cycloaddition of CO2 to various epoxides under ambient or mild conditions. DFT calculations and catalysis experiments revealed an intriguing bifunctional mechanism in the step of CO2 insertion involving different hydroxyl moieties (enediol, ethyldiol) of the ascorbic acid scaffold.

  17. Ascorbic acid as a bifunctional hydrogen bond donor for the synthesis of cyclic carbonates from CO2 under ambient conditions

    KAUST Repository

    Arayachukiat, Sunatda; Kongtes, Chutima; Barthel, Alexander; Vummaleti, Sai V. C.; Poater, Albert; Wannakao, Sippakorn; Cavallo, Luigi; D'Elia, Valerio

    2017-01-01

    Readily available ascorbic acid was discovered as an environmentally benign hydrogen bond donor (HBD) for the synthe-sis of cyclic organic carbonates from CO2 and epoxides in the presence of nucleophilic co-catalysts. The ascorbic acid/TBAI (TBAI: tetrabutylammonium iodide) binary system could be applied for the cycloaddition of CO2 to various epoxides under ambient or mild conditions. DFT calculations and catalysis experiments revealed an intriguing bifunctional mechanism in the step of CO2 insertion involving different hydroxyl moieties (enediol, ethyldiol) of the ascorbic acid scaffold.

  18. Overproduction of ligninolytic enzymes

    Science.gov (United States)

    Elisashvili, Vladimir; Kachlishvili, Eva; Torok, Tamas

    2014-06-17

    Methods, compositions, and systems for overproducing ligninolytic enzymes from the basidiomycetous fungus are described herein. As described, the method can include incubating a fungal strain of Cerrena unicolor IBB 303 in a fermentation system having growth medium which includes lignocellulosic material and then cultivating the fungal strain in the fermentation system under conditions wherein the fungus expresses the ligninolytic enzymes. In some cases, the lignocellulosic material is mandarin peel, ethanol production residue, walnut pericarp, wheat bran, wheat straw, or banana peel.

  19. Measurement of enzyme activity.

    Science.gov (United States)

    Harris, T K; Keshwani, M M

    2009-01-01

    To study and understand the nature of living cells, scientists have continually employed traditional biochemical techniques aimed to fractionate and characterize a designated network of macromolecular components required to carry out a particular cellular function. At the most rudimentary level, cellular functions ultimately entail rapid chemical transformations that otherwise would not occur in the physiological environment of the cell. The term enzyme is used to singularly designate a macromolecular gene product that specifically and greatly enhances the rate of a chemical transformation. Purification and characterization of individual and collective groups of enzymes has been and will remain essential toward advancement of the molecular biological sciences; and developing and utilizing enzyme reaction assays is central to this mission. First, basic kinetic principles are described for understanding chemical reaction rates and the catalytic effects of enzymes on such rates. Then, a number of methods are described for measuring enzyme-catalyzed reaction rates, which mainly differ with regard to techniques used to detect and quantify concentration changes of given reactants or products. Finally, short commentary is given toward formulation of reaction mixtures used to measure enzyme activity. Whereas a comprehensive treatment of enzymatic reaction assays is not within the scope of this chapter, the very core principles that are presented should enable new researchers to better understand the logic and utility of any given enzymatic assay that becomes of interest.

  20. Simultaneous Electrochemical Detection of Dopamine and Ascorbic Acid Using an Iron Oxide/Reduced Graphene Oxide Modified Glassy Carbon Electrode

    Directory of Open Access Journals (Sweden)

    Teo Peik-See

    2014-08-01

    Full Text Available The fabrication of an electrochemical sensor based on an iron oxide/graphene modified glassy carbon electrode (Fe3O4/rGO/GCE and its simultaneous detection of dopamine (DA and ascorbic acid (AA is described here. The Fe3O4/rGO nanocomposite was synthesized via a simple, one step in-situ wet chemical method and characterized by different techniques. The presence of Fe3O4 nanoparticles on the surface of rGO sheets was confirmed by FESEM and TEM images. The electrochemical behavior of Fe3O4/rGO/GCE towards electrocatalytic oxidation of DA was investigated by cyclic voltammetry (CV and differential pulse voltammetry (DPV analysis. The electrochemical studies revealed that the Fe3O4/rGO/GCE dramatically increased the current response against the DA, due to the synergistic effect emerged between Fe3O4 and rGO. This implies that Fe3O4/rGO/GCE could exhibit excellent electrocatalytic activity and remarkable electron transfer kinetics towards the oxidation of DA. Moreover, the modified sensor electrode portrayed sensitivity and selectivity for simultaneous determination of AA and DA. The observed DPVs response linearly depends on AA and DA concentration in the range of 1–9 mM and 0.5–100 µM, with correlation coefficients of 0.995 and 0.996, respectively. The detection limit of (S/N = 3 was found to be 0.42 and 0.12 µM for AA and DA, respectively.

  1. Ascorbic acid deficiency increases endotoxin influx to portal blood and liver inflammatory gene expressions in ODS rats.

    Science.gov (United States)

    Tokuda, Yuki; Miura, Natsuko; Kobayashi, Misato; Hoshinaga, Yukiko; Murai, Atsushi; Aoyama, Hiroaki; Ito, Hiroyuki; Morita, Tatsuya; Horio, Fumihiko

    2015-02-01

    The aim of this study was to determine whether ascorbic acid (AsA) deficiency-induced endotoxin influx into portal blood from the gastrointestinal tract contributes to the inflammatory changes in the liver. The mechanisms by which AsA deficiency provokes inflammatory changes in the liver were investigated in Osteogenic Disorder Shionogi (ODS) rats (which are unable to synthesize AsA). Male ODS rats (6-wk-old) were fed a diet containing sufficient (300 mg/kg) AsA (control group) or a diet without AsA (AsA-deficient group) for 14 or 18 d. On day 14, the hepatic mRNA levels of acute-phase proteins and inflammation-related genes were significantly higher in the AsA-deficient group than the control group, and these elevations by AsA deficiency were exacerbated on day 18. The serum concentrations of interleukin (IL)-1β and IL-6, which induce acute-phase proteins in the liver, were also significantly elevated on day 14 in the AsA-deficient group compared with the respective values in the control group. IL-1β mRNA levels in the liver, spleen, and lung were increased by AsA deficiency. Moreover, on both days 14 and 18, the portal blood endotoxin concentration was significantly higher in the AsA-deficient group than in the control group, and a significant correlation between serum IL-1β concentrations and portal endotoxin concentrations was found in AsA-deficient rats. In the histologic analysis of the ileum tissues, the number of goblet cells per villi was increased by AsA deficiency. These results suggest that AsA deficiency-induced endotoxin influx into portal blood from the gastrointestinal tract contributes to the inflammatory changes in the liver. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Study of radio-protective effects of ascorbic acid in rates

    International Nuclear Information System (INIS)

    Bakir, A.M.; Mohammad, A.

    2011-06-01

    The aim of this study was to evaluate the potential radio-protective effects of different ascorbic acid concentrations (vitamin C) in rats before whole body irradiation with total dose of 7 Gy ( 60 Co source) using two different dose rates of 1 and 0.55 Gy.min -1 by increasing percent of surviving. In the first group (1 Gy/m); rats were administered four different concentrations of ascorbic acid (7.5, 12.5, 100, 200 mg/kg b wt ) in drinking water for 30 days before irradiation starting from the ablactation which considered as day 0. Whereas, in the second group (0.55 Gy/m); rats were administered six different concentrations of ascorbic acid (1, 5, 7.5, 12.5, 100, 200 mg/kg b wt) before irradiation with total dose 7 Gy ( 60 Co source). The results have showed that the ascorbic acid enhance the 30-day survival of irradiated rats in 1 and 0.55 Gy/m groups, compared to the control group. The mean cumulated probability of survival of rats (1 Gy/m group) was 66%± 6 (Mean± S.E), 69%± 5, 52%± 9 and 51%± 9 in groups of rats which administered 7.5, 12.5, 100, 200 mg/kg, respectively, versus 41%± 9 in control group for 14 days. While, it was 90%± 2, 90%± 2, 88%± 2, 94%± 1, 84%± 3 and 78%± 3 in groups of rats which administered 1, 5, 7.5, 12.5, 100, 200 mg/kg respectively, versus 52%± 6 in control group for 30 days. Our data, also, indicated that all ascorbic acid concentrations in both groups had significant reduction in mortality and increasing percent of surviving compared to the control groups. We conclude that all ascorbic acid concentrations which used in both groups (1 and 0.55 Gy/m), had radioprotective effects in rats when administrated before irradiations, and this role was more effective against lower dose rate of radiation exposure. (author)

  3. Data supporting the role of enzymes and polysaccharides during cassava postharvest physiological deterioration.

    Science.gov (United States)

    Uarrota, Virgílio Gavicho; Moresco, Rodolfo; Schmidt, Eder Carlos; Bouzon, Zenilda Laurita; da Costa Nunes, Eduardo; de Oliveira Neubert, Enilto; Peruch, Luiz Augusto Martins; Rocha, Miguel; Maraschin, Marcelo

    2016-03-01

    This data article is referred to the research article entitled The role of ascorbate peroxidase, guaiacol peroxidase, and polysaccharides in cassava (Manihot esculenta Crantz) roots under postharvest physiological deterioration by Uarrota et al. (2015). Food Chemistry 197, Part A, 737-746. The stress duo to PPD of cassava roots leads to the formation of ROS which are extremely harmful and accelerates cassava spoiling. To prevent or alleviate injuries from ROS, plants have evolved antioxidant systems that include non-enzymatic and enzymatic defence systems such as ascorbate peroxidase, guaiacol peroxidase and polysaccharides. In this data article can be found a dataset called "newdata", in RData format, with 60 observations and 06 variables. The first 02 variables (Samples and Cultivars) and the last 04, spectrophotometric data of ascorbate peroxidase, guaiacol peroxidase, tocopherol, total proteins and arcsined data of cassava PPD scoring. For further interpretation and analysis in R software, a report is also provided. Means of all variables and standard deviations are also provided in the Supplementary tables ("data.long3.RData, data.long4.RData and meansEnzymes.RData"), raw data of PPD scoring without transformation (PPDmeans.RData) and days of storage (days.RData) are also provided for data analysis reproducibility in R software.

  4. Deoxynukleosidkinase aus insektenzellen zur Nukleosidmonophosphat synthese

    DEFF Research Database (Denmark)

    1998-01-01

    The patent application together with Roche on synthesis of monophosphate nucleotides by Dm-dNK, an enzyme isolated and the corresponding gene cloned in our laboratory.......The patent application together with Roche on synthesis of monophosphate nucleotides by Dm-dNK, an enzyme isolated and the corresponding gene cloned in our laboratory....

  5. Solubilities of magnesium-L-ascorbate, calcium-L-ascorbate, magnesium-L-glutamate, magnesium-D-gluconate, calcium-D-gluconate, calcium-D-heptagluconate, L-aspartic acid, and 3-nitrobenzoic acid in water

    Energy Technology Data Exchange (ETDEWEB)

    Mishelevich, Alexander [Department of Chemical Engineering, Ben Gurion University of the Negev, Beer Sheva 84105 (Israel); Apelblat, Alexander [Department of Chemical Engineering, Ben Gurion University of the Negev, Beer Sheva 84105 (Israel)], E-mail: apelblat@bgu.ac.il

    2008-05-15

    The solubility in water of magnesium-L-ascorbate, calcium-L-ascorbate, magnesium-L-glutamate, magnesium-D-gluconate, calcium-D-gluconate, calcium-D-heptagluconate, L-aspartic acid, and 3-nitrobenzoic acid was determined in the 278.15 K to 343.15 K temperature range. The solubility of these compounds served to permit the evaluation of the apparent molar enthalpies of solution.

  6. Solubilities of magnesium-L-ascorbate, calcium-L-ascorbate, magnesium-L-glutamate, magnesium-D-gluconate, calcium-D-gluconate, calcium-D-heptagluconate, L-aspartic acid, and 3-nitrobenzoic acid in water

    International Nuclear Information System (INIS)

    Mishelevich, Alexander; Apelblat, Alexander

    2008-01-01

    The solubility in water of magnesium-L-ascorbate, calcium-L-ascorbate, magnesium-L-glutamate, magnesium-D-gluconate, calcium-D-gluconate, calcium-D-heptagluconate, L-aspartic acid, and 3-nitrobenzoic acid was determined in the 278.15 K to 343.15 K temperature range. The solubility of these compounds served to permit the evaluation of the apparent molar enthalpies of solution

  7. Increased expression of native cytosolic Cu/Zn superoxide dismutase and ascorbate peroxidase improves tolerance to oxidative and chilling stresses in cassava (Manihot esculenta Crantz).

    Science.gov (United States)

    Xu, Jia; Yang, Jun; Duan, Xiaoguang; Jiang, Yueming; Zhang, Peng

    2014-08-05

    Cassava (Manihot esculenta Crantz) is a tropical root crop, and is therefore, extremely sensitive to low temperature; its antioxidative response is pivotal for its survival under stress. Timely turnover of reactive oxygen species (ROS) in plant cells generated by chilling-induced oxidative damages, and scavenging can be achieved by non-enzymatic and enzymatic reactions in order to maintain ROS homeostasis. Transgenic cassava plants that co-express cytosolic superoxide dismutase (SOD), MeCu/ZnSOD, and ascorbate peroxidase (APX), MeAPX2, were produced and tested for tolerance against oxidative and chilling stresses. The up-regulation of MeCu/ZnSOD and MeAPX2 expression was confirmed by the quantitative reverse transcriptase-polymerase chain reaction, and enzymatic activity analyses in the leaves of transgenic cassava plant lines with a single-transgene integration site. Upon exposure to ROS-generating agents, 100 μM ROS-generating reagent methyl viologen and 0.5 M H₂O₂, higher levels of enzymatic activities of SOD and APX were detected in transgenic plants than the wild type. Consequently, the oxidative stress parameters, such as lipid peroxidation, chlorophyll degradation and H₂O₂ synthesis, were lower in the transgenic lines than the wild type. Tolerance to chilling stress at 4°C for 2 d was greater in transgenic cassava, as observed by the higher levels of SOD, catalase, and ascorbate-glutathione cycle enzymes (e.g., APX, monodehydroascorbate reductase, dehydroascorbate reducatase and glutathione reductase) and lower levels of malondialdehyde content. These results suggest that the expression of native cytosolic SOD and APX simultaneously activated the antioxidative defense mechanisms via cyclic ROS scavenging, thereby improving its tolerance to cold stress.

  8. Dog rose (Rosa canina L.) as a functional ingredient in porcine frankfurters without added sodium ascorbate and sodium nitrite.

    Science.gov (United States)

    Vossen, Els; Utrera, Mariana; De Smet, Stefaan; Morcuende, David; Estévez, Mario

    2012-12-01

    The effect of dog rose (Rosa canina L.; RC), rich in polyphenols and ascorbic acid, on lipid and protein oxidation, colour stability and texture of frankfurters was investigated. Four treatments were prepared: with 5 or 30 g/kg RC extract and without sodium ascorbate and sodium nitrite (5RC and 30RC, respectively), a positive control (with sodium ascorbate and sodium nitrite; PC) and a negative control (without sodium ascorbate, sodium nitrite or RC extract; NC). Hexanal values were much higher throughout storage in NC compared to RC and PC frankfurters (Prose can act as a natural antioxidant in frankfurters, but not as full replacer for sodium nitrite. Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. Preparation of glucoheptonate - sup(99m) Tc using stannous ascorbate as reducing agent for TcO-4 ion

    International Nuclear Information System (INIS)

    Barboza, M.R.F.F. de; Silva, C.P.G. da.

    1983-12-01

    A preparation procedure of stannous ascorbate in lyophilized form is presented. This reducing agent was employed for the preparation of kits of calcium glucoheptonate (GHA) to be labelled with sup(99m) Tc for use in kidney scintigraphy. Comparative studies between kits prepared with stannous ascorbate and those prepared with stannous chloride as reducing agent were made. The labelling yield during 18 hours after the addition of sup(99m) TcO - 4 was higher when stannous ascorbate was used. The stability of kits of calcium glucoheptonate - sup(99m) Tc containing stannous ascorbate was studied during five months after its preparation in the lyophilized form. On the fifth month the labelling yield of GHA - sup(99m) Tc was 89-95%, being therefore suitable for kidney scintigraphy. (Author) [pt

  10. Pre-sowing application of ascorbic acid and salicylic acid to seed of pumpkin and seedling response to salt

    International Nuclear Information System (INIS)

    Rafique, N.; Raza, S.H.; Qasim, M.; Iqbal, N.

    2011-01-01

    The effects of seed soaking with salicylic acid or ascorbic acid on pumpkin seedlings growth under saline (10 dS m/sup -1/) conditions were investigated. Seedlings fresh weight, protein contents, protease and nitrate reductase activities were significantly affected by 15 and 30 mg L/sup -1/ salicylic acid and 30 mg L/sup -1/ ascorbic acid priming treatments, under both normal and saline conditions. Priming reduced the severity of the salt stress, the amelioration was better due to 30 mg L/sup -1/ ascorbic acid or 30 mg L/sup -1/ salicylic acid treatments as these treatments showed best results on seedling growth, fresh and dry matter production under non-saline and saline environments. Application of seed priming with ascorbic acid and salicylic acid in pumpkin ameliorate the adverse effects of salt stress. (author)

  11. Influence of ascorbic acid on in vivo amidation of alpha-melanocyte stimulating hormone in guinea pig pituitary

    DEFF Research Database (Denmark)

    Fenger, M; Hilsted, L

    1988-01-01

    The effect of ascorbic acid depletion on the amidation of alphamelanocyte stimulating hormone (alpha MSH) was studied in vivo in guinea pig pituitary. After four weeks, the concentration of ascorbic acid was 1.20 +/- 0.11 mumol/g tissue (mean +/- SD) in the pituitary and 0.34 +/- 0.07 mumol......-39) immunoreactivity was observed in the depleted guinea pigs. Gel chromatography and reversed-phase high-performance luquid chromatography showed that the alpha MSH and ACTH (1-14) immunoreactivity was of low molecular weight and partly mono- or diacetylated. Depletion of ascorbic acid had no influence on the degree...... of acetylation of alpha MSH and ACTH (1-14). It is concluded that depletion of ascorbic acid reduces the in vivo amidation of ACTH (1-14) in the guinea pig pituitary....

  12. Changes in enzymes, phenolic compounds, tannins, and vitamin C in various stages of jambolan (Syzygium cumini Lamark development

    Directory of Open Access Journals (Sweden)

    Taís Silva de Oliveira Brandão

    2011-12-01

    Full Text Available The physiological state of a fruit is closely related to ripening and climatic conditions during the growing period when the fruit undergo changes in color, texture, and flavor. The ripening of the fruit can involve a complex series of biochemical reactions with alteration in enzymes activities, phenols, tannins, and ascorbic acid. The activity of enzymes (carboximethylcellulase, polygalacturonase, and pectinlyase, the total concentration of phenolic compounds, condensed tannins, and vitamin C in five stages of maturation were studied. Significant changes were observed between the maturity stages. The phenolic compounds were higher at green stage (705.01 ± 7.41; tannins were higher at green/purple stage (699.45 ± 0.22. The results showed that the ascorbic acid levels of the pulp varied significantly from 50.81 ± 1.43 to 6.61 ± 1.04 mg.100 g-1 during maturation. The specific activity of pectin lyase was higher at green stage (1531.90 ± 5.83. The specific activity of polygalacturonase was higher at mature stage (1.83 ± 0.0018. The specific activity of carboximetilcelulose was higher at ripe mature stage (4.61 ± 0.0024. The low ascorbic acid content found in jambolan fruit indicates that this fruit is not a rich source of this nutrient; however, other characteristics can make jambolan products fit for human consumption.

  13. [The effect of gamma rays on glutathion and ascorbic acid content in rabbit lenses (author's transl)].

    Science.gov (United States)

    Zygulska-Mach, H; Mach, Z

    1975-01-01

    It is pointed out that the partner non radiated eye is also influenced after employment of high radiation on an eye. The authors radiated rabbit eyes with gamma rays employing Stallard-applicators and determined the glutathion and ascorbic acid content in the lenses. The lenses of the partner eye were also examined for comparison. In those eyes which were directly radiated there was a fall of concentration of the two substances indirectly proportional to the dose of rays employed. In the partner eyes which were not directly subjected to direct radiation there were changes of similar character which were however not so much pronounced. The role of glutathion and ascorbic acid in lens metabolism is pointed out.

  14. Effect of molybdenum status on the ascorbic acid content of plants in sand culture

    Energy Technology Data Exchange (ETDEWEB)

    Hewitt, E J; Agarwala, S C; Jones, E W

    1950-12-30

    The role of molybdenum in higher plants is generally thought to be closely connected with the assimilation of nitrate nitrogen. The nature of the system involved in nitrate assimilation and the step activated by molybdenum are still obscure. Preliminary results are presented which indicate that molydenum deficiency consistently causes a striking and generally significant reduction in the apparent ascorbic acid content of several crops. Molydenum-deficient plants were also injected through the petioles with molybdenum; there was a detectable rise in ascorbic acid content in 24 hr. The first visual response to molybdenum was just perceptible in three days as chlorophyll formation, and growth response could be detected about seven days after injection. Several hypotheses to account for the results obtained are discussed. 13 references, 1 table.

  15. Irradiation and modified atmosphere packaging effects on residual nitrite, ascorbic acid, nitrosomyoglobin, and color in sausage.

    Science.gov (United States)

    Ahn, Hyun-Joo; Jo, Cheorun; Lee, Ju-Woon; Kim, Jae-Hyun; Kim, Kee-Hyuk; Byun, Myung-Woo

    2003-02-26

    The present study was undertaken to evaluate the irradiation and modified atmosphere packaging effects on emulsion-type cooked pork sausage during storage for 4 weeks. CO(2) (100%), N(2) (100%), or 25% CO(2)/75% N(2) packaged sausage were irradiated at 0, 5, and 10 kGy, and residual nitrite, residual ascorbic acid, nitrosomyoglobin (NO-Mb), color values, and their correlation were observed. Irradiation significantly reduced the residual nitrite content and caused partial reduction of NO-Mb during storage. No difference was observed in ascorbic acid content by irradiation. Irradiation decreased the Hunter color a value of sausage. CO(2) or CO(2)/N(2) packaging were more effective for reducing residual nitrite and inhibiting the loss of the red color of sausage compared to N(2) packaging. Results indicated that the proper combination of irradiation and modified atmosphere packaging could reduce the residual nitrite in sausage with minimization of color change.

  16. Enhancing Lipid Stability in Irradiated Beef Mince by Oleoresins and/ or Ascorbic Acid during Chilling Storage

    International Nuclear Information System (INIS)

    Zahran, D.A.

    2008-01-01

    Lipid Oxidation, fatty acids profile and sensory properties of irradiated beef mince (2.5 kGy) treated with oleoresins (rosemary or ginger), ascorbic acid, or combination of ascorbic acid and oleoresins were investigated during 30 days of chilled storage. Thiobarbituric acid reactive substances (TBARS) as an indication of lipid oxidation, of irradiated control samples were significantly higher than those of non irradiated control and samples treated with rosemary and ginger oleoresins. By GC-MS analysis, it was found that the relative percentage of total saturated fatty acids (TSFA) increased in all treatments. However, the highest increase was recorded in irradiated control samples compared to non irradiated control samples. Beef mince samples treated with oleoresins (rosemary or ginger) had the best scores for discoloration and off odour. Thus, the addition of oleoresins (rosemary or ginger) to beef mince before irradiation could be an easily applied method to minimize oxidative degradation of irradiated meat

  17. Effects of dietary chromium exposure to rockfish, Sebastes schlegelii are ameliorated by ascorbic acid.

    Science.gov (United States)

    Kim, Jun-Hwan; Kang, Ju-Chan

    2017-05-01

    Juvenile rockfish Sebastes schlegelii (mean length 10.8±1.4cm, and mean weight 31.7±3.6g) were exposed for 4 weeks with the different levels of dietary chromium (Cr 6+ ) at 0, 120 and 240mg/L and ascorbic acids (AsA) at 100, 200 and 400mg/L. Significant accumulation occurred in specific tissues and hematological parameters were altered: red blood cell count, hematocrit, and hemoglobin increased; plasma components were altered including calcium, glucose, cholesterol, total protein, glutamic oxalate transaminase, and glutamic pyruvate transaminase. However, magnesium and alkaline phosphatase concentrations were unchanged. Ascorbic acids reduced both chromium uptake into tissues and altered hematological parameters. Copyright © 2017. Published by Elsevier Inc.

  18. The electrochemical synthesis of polyaniline/polysulfone composite films and electrocatalytic activity for ascorbic acid oxidation

    International Nuclear Information System (INIS)

    Hu Zhongai; Shang Xiuli; Yang Yuying; Kong Chao; Wu Hongying

    2006-01-01

    Polyaniline (PANI)/polysulfone (PSF) composite films with asymmetric porous structure were successfully prepared by electropolymerization. The back face (in contact with the electrode) of the freestanding composite film is green while the outer face is white. The chemical component and the morphology of the surfaces were characterized by FTIR spectra and scanning electron microscopy, respectively. It was shown that replicate films gave reproducible voltammetry in 0.5 M H 2 SO 4 . The influence of the electrolyte and the acidic concentration on the redox peak currents of polyaniline were investigated in detail. The composite film electrode showed good electrocatalytic activity for ascorbic acid, which the anodic overpotential was evidently reduced compared with that obtained at bare Pt electrode. The diffusion coefficient of ascorbic acid was 1.38 x 10 -6 cm 2 s -1

  19. Method to synthesize metal chalcogenide monolayer nanomaterials

    Science.gov (United States)

    Hernandez-Sanchez, Bernadette A.; Boyle, Timothy J.

    2016-12-13

    Metal chalcogenide monolayer nanomaterials can be synthesized from metal alkoxide precursors by solution precipitation or solvothermal processing. The synthesis routes are more scalable, less complex and easier to implement than other synthesis routes.

  20. nanoparticles synthesized by citrate precursor m

    African Journals Online (AJOL)

    user

    (M=Co, Cu) nanoparticles synthesized by citrate precursor method ... The structural characterization was carried out using an X-ray Diffractometer (Rikagu Miniflex, Japan) ..... His current area of interest includes magnetic nanomaterials.

  1. Syntheses, molecular and crystalline architectures, and ...

    Indian Academy of Sciences (India)

    Syntheses, molecular and crystalline architectures, and luminescence behaviour of terephthalate bridged heptacoordinated dinuclear lead(II) complexes containing a pentadentate N-donor Schiff base. SUBHASIS ROYa, SOMNATH CHOUBEYa, SUMITAVA KHANa, KISHALAY BHARa,. PARTHA MITRAb and BARINDRA ...

  2. Synthese en chemotherapeutisch onderzoek van sulfanilamidopyrimidinen

    NARCIS (Netherlands)

    Grevenstuk, Anton Bernard

    1942-01-01

    In order to investigate the influence of substitution in the pyrimidine nucleous on the activity of the three isomeric sulfanilamidopyrimidines (2, 5 and 6), a number of substituted sulfanilamidopyrimidines were synthesized and tested on chemotherapeutic activity. ... Zie: Summary

  3. Random-walk enzymes

    Science.gov (United States)

    Mak, Chi H.; Pham, Phuong; Afif, Samir A.; Goodman, Myron F.

    2015-09-01

    Enzymes that rely on random walk to search for substrate targets in a heterogeneously dispersed medium can leave behind complex spatial profiles of their catalyzed conversions. The catalytic signatures of these random-walk enzymes are the result of two coupled stochastic processes: scanning and catalysis. Here we develop analytical models to understand the conversion profiles produced by these enzymes, comparing an intrusive model, in which scanning and catalysis are tightly coupled, against a loosely coupled passive model. Diagrammatic theory and path-integral solutions of these models revealed clearly distinct predictions. Comparison to experimental data from catalyzed deaminations deposited on single-stranded DNA by the enzyme activation-induced deoxycytidine deaminase (AID) demonstrates that catalysis and diffusion are strongly intertwined, where the chemical conversions give rise to new stochastic trajectories that were absent if the substrate DNA was homogeneous. The C →U deamination profiles in both analytical predictions and experiments exhibit a strong contextual dependence, where the conversion rate of each target site is strongly contingent on the identities of other surrounding targets, with the intrusive model showing an excellent fit to the data. These methods can be applied to deduce sequence-dependent catalytic signatures of other DNA modification enzymes, with potential applications to cancer, gene regulation, and epigenetics.

  4. Synthesizing and salvaging NAD: lessons learned from Chlamydomonas reinhardtii.

    Directory of Open Access Journals (Sweden)

    Huawen Lin

    2010-09-01

    Full Text Available The essential coenzyme nicotinamide adenine dinucleotide (NAD+ plays important roles in metabolic reactions and cell regulation in all organisms. Bacteria, fungi, plants, and animals use different pathways to synthesize NAD+. Our molecular and genetic data demonstrate that in the unicellular green alga Chlamydomonas NAD+ is synthesized from aspartate (de novo synthesis, as in plants, or nicotinamide, as in mammals (salvage synthesis. The de novo pathway requires five different enzymes: L-aspartate oxidase (ASO, quinolinate synthetase (QS, quinolate phosphoribosyltransferase (QPT, nicotinate/nicotinamide mononucleotide adenylyltransferase (NMNAT, and NAD+ synthetase (NS. Sequence similarity searches, gene isolation and sequencing of mutant loci indicate that mutations in each enzyme result in a nicotinamide-requiring mutant phenotype in the previously isolated nic mutants. We rescued the mutant phenotype by the introduction of BAC DNA (nic2-1 and nic13-1 or plasmids with cloned genes (nic1-1 and nic15-1 into the mutants. NMNAT, which is also in the de novo pathway, and nicotinamide phosphoribosyltransferase (NAMPT constitute the nicotinamide-dependent salvage pathway. A mutation in NAMPT (npt1-1 has no obvious growth defect and is not nicotinamide-dependent. However, double mutant strains with the npt1-1 mutation and any of the nic mutations are inviable. When the de novo pathway is inactive, the salvage pathway is essential to Chlamydomonas for the synthesis of NAD+. A homolog of the human SIRT6-like gene, SRT2, is upregulated in the NS mutant, which shows a longer vegetative life span than wild-type cells. Our results suggest that Chlamydomonas is an excellent model system to study NAD+ metabolism and cell longevity.

  5. CAMAC programmable-control frequency synthesizer

    International Nuclear Information System (INIS)

    Yumaguzin, T.Kh.; Vyazovkin, D.E.; Nazirov, Eh.P.; Tuktarov, R.F.

    1989-01-01

    Synthesizer allows to set frequency with 0.015% accuracy and to scan it with variable step. Frequency controlled divider with further summing-up of divided frequency with fundamental one is used in synthesizer, and it has allowed to use digit of the input code and to obtain 3-4 MHz frequency range. Variation of operation flowsheet in the other frequency range is possible. K-155 and K-531 series microcircuits were used during development

  6. Operational Design that Synthesizes Art and Science

    Science.gov (United States)

    2011-05-04

    FINAL 3. DATES COVERED (From - To) Feb - May 2011 4. TITLE AND SUBTITLE OPERATIONAL DESIGN THAT SYNTHESIZES ART AND SCIENCE 5a...TITLE AND SUBTITLE Operational Design That Synthesizes Art And Science 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR...proponents of EBO view warfare as only a science and not a combination of art and science . 9 Another main point of contention centered on the term

  7. Raman assisted lightwave synthesized frequency sweeper

    DEFF Research Database (Denmark)

    Pedersen, Anders Tegtmeier; Rottwitt, Karsten

    2010-01-01

    We present a Lightwave Synthesized Frequency Sweeper comprising a Raman amplifier for loss compensation. The generated pulse train contains 123 pulses and has a flat signal level as well as a low noise level.......We present a Lightwave Synthesized Frequency Sweeper comprising a Raman amplifier for loss compensation. The generated pulse train contains 123 pulses and has a flat signal level as well as a low noise level....

  8. Oxidation of ascorbic acid by a (salen)ruthenium(VI) nitrido complex in aqueous solution.

    Science.gov (United States)

    Wang, Qian; Man, Wai-Lun; Lam, William W Y; Lau, Tai-Chu

    2014-12-25

    The oxidation of ascorbic acid (H2A) by [Ru(VI)(N)(L)(MeOH)](+) in aqueous acidic solutions has the following stoichiometry: 2[Ru(VI)(N)] + 3H2A → 2[Ru(III)(NH2-HA)](+) + A. Mechanisms involving HAT/N-rebound at low pH (≤2) and nucleophilic attack at the nitride at high pH (≥5) are proposed.

  9. Application of 10% Ascorbic Acid Improves Resin Shear Bond Stregth in Bleached Dentin

    Directory of Open Access Journals (Sweden)

    Kamizar Kamizar

    2014-10-01

    Full Text Available Normal 0 false false false IN X-NONE X-NONE MicrosoftInternetExplorer4 Restoration of the teeth immediately after bleaching with H2O2 35% is contraindicated due to the remnants of free radical that will stay inside dentin for 2-3 weeks which will compromise the adhesiveness of composite resin. Objective: The aim of this study was to evaluate the influence of 10% ascorbic acid on shear bond strength of composite placed on bleached dentin. Methods:Twenty seven samples were divided equally into three groups. Group 1: dentin was etched with 35% phosphoric acid; Group 2: dentin was bleached with 35% H2O2 followed by etching with 35% phosphoric acid; Group 3: dentin was bleached with 35% H2O2, followed by application of 10% ascorbic acid and etched with 35% phosphoric acid. All samples were then stored at 370C for 24 hours. The Universal Testing Machine was used to measure shear bond strength and the results were analyzed with Kruskal Wallis and Mann Whitney test. Results: After nine independent experiments, 10% ascorbic acid application on bleached dentin resulted in highest increased in bond stregth (56.04±11.06MPa compared to Group 2 (29.09±7.63MPa and Group 1 (25.55±2.22MPa and the difference was statistically significant (p<0.05. Conclusion: Application of 10% ascorbic acid to the bleached dentin improved the shear bond strength of resin composite.

  10. Amelioration of High Cholesterol Diet Caused Lipids Accumulation in Hepatic Cells by Rutin and Ascorbic Acid

    OpenAIRE

    Abdulaziz M. Aleisa

    2013-01-01

    Non Alcoholic Fatty Liver Disease (NAFLD) has become a very common metabolic disorder. It refers to a group of conditions where excess fats are deposited in hepatic cells. Several approaches have been considered for the management of NAFLD including dietary changes, which were reported to suppress hepatic lipids accumulation in previous studies. The present study was designed to investigate the possible synergistic effects of Rutin (RT) and Ascorbic Acid (AA) against lipids accumulation in he...

  11. Antioxidant capacity and contents of phenols, ascorbic acid, β-carotene and lycopene in lettuce

    OpenAIRE

    Zdravković Jasmina M.; Aćamović-Đoković Gordana S.; Mladenović Jelena D.; Pavlović Radoš M.; Zdravković Milan S.

    2014-01-01

    The antioxidant activity of three lettuce varieties (Lactuca sativa L.) Emerald, Vera and Neva, cultivated in two kinds of protected spaces, a glasshouse and a plastic greenhouse, under controlled conditions, was determined. The content of antioxidant compounds: total phenols, flavonoids, L-ascorbic acid, ß-carotene and lycopene, were determined in ethanolic extracts of the lettuce with spectrophotometric methods. The largest content of total phenols (78.98...

  12. Highly efficient differentiation of embryonic stem cells into adipocytes by ascorbic acid

    OpenAIRE

    Ixchelt Cuaranta-Monroy; Zoltan Simandi; Zsuzsanna Kolostyak; Quang-Minh Doan-Xuan; Szilard Poliska; Attila Horvath; Gergely Nagy; Zsolt Bacso; Laszlo Nagy

    2014-01-01

    Adipocyte differentiation and function have become the major research targets due to the increasing interest in obesity and related metabolic conditions. Although, late stages of adipogenesis have been extensively studied, the early phases remain poorly understood. Here we present that supplementing ascorbic acid (AsA) to the adipogenic differentiation cocktail enables the robust and efficient differentiation of mouse embryonic stem cells (mESCs) to mature adipocytes. Such ESC-derived adipocy...

  13. Role of ascorbic acid supplement in reducing oxidative stress and hepatotoxicity in lead intoxication

    International Nuclear Information System (INIS)

    Farooq, Y.; Hussain, M.M.; Aleem, S.B.

    2013-01-01

    Objective: The present study was conducted to measure the oxidative stress and hepatotoxicity in lead intoxicated sprague dawley rats with and without supplementation of ascorbic acid. Study Design: Randomized Control Trial. Place of Study: Physiology Department, Army Medical College, Rawalpindi. (From Oct 2007 to Sep 2008) Material and Methods: One hundred and five male rats (age, 90-120 days; weight 200 - 250 gm) were divided into three groups each having 35 rats. Rats of group 1 and group 2 were given weekly injections of sodium acetate (10 mg /kg body weight) and lead acetate (10 mg /kg body weight) respectively, whereas rats of group 3 were administered lead acetate(10 mg /kg body weight) through weekly injections and ascorbic acid in drinking water (500 mg/l). After 6 weeks, 4 ml of blood was drawn from each rat by cardiac puncture. The blood was allowed to clot and serum was separated for estimation of serum malondialdehyde (MDA) levels on spectrophotometer; and serum alanine aminotransferase (ALT) levels and aspartate aminotransferase (AST) levels on Merck Micorlab 200. Results: Lead intoxication of rats revealed that serum MDA levels were raised to 7.8 +- 0.48 micro mol/l (control, 3.2 +-0.39 micro mol/l), ALT levels to 76.26 +- 5.88 IU/l (control, 44.1 +- 3.26) and AST levels to 258.06 +- 13.30 IU/l (control, 156.2 +- 4.97). Ascorbic acid supplementation significantly lowered serum MDA levels (3.8 +- 0.34 micro mol/l), ALT levels (52.26 +-4.57 IU/l) and AST levels (188.13 +- 12.91 IU/l). Conclusion: Ascorbic acid supplementation ameliorates lead intoxication probably by reducing the oxidative stress, thus preventing the development of hepatotoxicity, but this amelioration is not equal to the control. (author)

  14. Ascorbic acid prevents nonreceptor specific binding of [3H]-5-hydroxytryptamine to bovine cerebral cortex membranes

    International Nuclear Information System (INIS)

    Hamblin, M.W.; Adriaenssens, P.I.; Ariani, K.; Cawthon, R.M.; Stratford, C.A.; Tan, G.L.; Ciaranello, R.D.

    1987-01-01

    [ 3 H]-5-Hydroxytryptamine ([ 3 H]-5-HT) decomposes rapidly when exposed to air in solution at physiological pH if antioxidants are not present. The decomposition products appear to bind to two saturable sites on brain membranes (apparent Kd values = 1-2 and 100-1000 nM). This binding mimics ''specific'' ligand/receptor binding in that it is inhibited by 10 microM unlabeled 5-HT. This inhibition is not competitive, but rather is due to the prevention of [ 3 H]-5-HT breakdown by excess unlabeled 5-HT. Unlike genuine ligand/receptor binding, the binding of [ 3 H]-5-HT breakdown products is essentially irreversible and does not display a tissue distribution consistent with binding to authentic 5-HT receptors. [ 3 H]-5-HT decomposition can be eliminated by the inclusion of 0.05 to 5 mM ascorbic acid. At these concentrations ascorbic acid is not deleterious to reversible [ 3 H]-5-HT binding. When [ 3 H] 5-HT exposure to air occurs in the presence of brain membranes, the apparent antioxidant activity of brain membranes themselves affords protection against [ 3 H]-5-HT degradation equal to ascorbic acid. This protection is effective below final [ 3 H]-5-HT concentrations of 10 nM. Above 10 nM [ 3 H]-5-HT, addition of ascorbic acid or other antioxidants is necessary to avoid the occurrence of additional low affinity (apparent Kd = 15-2000 nM) binding sites that are specific but nonetheless irreversible. When care is taken to limit [ 3 H]-5-HT oxidation, the only reversible and saturable specific binding sites observed are of the 5-HT1 high affinity (Kd = 1-2 nM) type. Radioligand oxidation artifacts may be involved in previous reports of low affinity (Kd = 15-250 nM) [ 3 H]-5-HT binding sites in brain membrane preparations

  15. Validation of ascorbic acid tablets of national production by igh-performance liquid chromatography method

    International Nuclear Information System (INIS)

    Rodriguez Hernandez, Yaslenis; Suarez Perez, Yania; Izquierdo Castro, Idalberto

    2009-01-01

    We validate an analytical method by high-performance liquid chromatography to determine ascorbic acid proportion in vitamin C tablets, which was designed as an alternative method to quality control and to follow-up of active principle chemical stability, since official techniques to quality control of ascorbic acid in tablets are not selective with degradation products. Method was modified according to that reported in USP 28, 2005 for analysis of injectable product. We used a RP-18 column of 250 x 4.6 mm 5 μm with a UV detector to 245 nm. Its validation was necessary for both objectives, considering parameters required for methods of I and II categories. This method was enough linear, exact, and precise in the rank of 100-300 μg/mL. Also, it was selective with remaining components of matrix and with the possible degradation products achieved in stressing conditions. Detection and quantification limits were estimated. When method was validated it was applied to ascorbic acid quantification in two batches of expired tablets and we detected a marked influence of container in active degradation principle after 12 months at room temperature. (Author)

  16. Genotoxicity and oxidative stress of microwave radiation role of ascorbic acid

    International Nuclear Information System (INIS)

    Desouky, O.S.; Abdel Karim, M.A.; Deiaa El Deen, D.A.; Nayal, N.A.

    2005-01-01

    Radiofrequency fields and especially microwaves are very important part of electromagnetic spectrum that can produce generations of reactive oxygen species, and thus can affect DNA and cause chromosomal aberrations. So this effect can be diminished by the supplement of an antioxidant such as ascorbic acid. In this study, the proposed protective role of ascorbic acid was tested against the EMF induced chromosomal aberrations and lipid peroxidation. The present study proved that EMF had a clastogenic effect on the bone marrow cells of mice, either with the exposure to EMF; 950 MHz or frequency EMF; 2450 MHz. This effect was evidenced by structural and numerical chromosomal aberrations. The study also proved that EMF had an effect on oxidative stress, evidenced by increase in the level of lipid peroxide, in a dose dependent manner. So, the mechanism of EMF induced chromosomal aberrations can be explained by this oxidative stress induced by EMF exposure. The present study showed that ascorbic acid had a protective effect against both EMF induced chromosomal aberrations and oxidative stress, when it is applied concomitantly with EMF exposure either at frequency of 950 MHz or 2450 MHz. this is evident by decreases in the level of lipid peroxide and decrease in chromosomal aberrations

  17. Clinical efficacy of 25% L-ascorbic acid (C'ensil) in the treatment of melasma.

    Science.gov (United States)

    Hwang, Seon-Wook; Oh, Doo-Jin; Lee, Deborah; Kim, Jung-Wook; Park, Sung-Wook

    2009-01-01

    L-Ascorbic acid is used to treat melasma; however, it is quickly oxidized in aqueous solutions. Thus, C'ensil, a formulation containing 25% l-ascorbic acid and a chemical penetration enhancer, was created to promote the penetration of l-ascorbic acid into the skin. To evaluate the efficacy of C'ensil in patients with melasma. Forty subjects with melasma were treated with C'ensil during an open-label trial over a period of 16 weeks. Each subject's skin pigmentation was assessed every 4 weeks using the Melasma Area and Severity Index (MASI) and mexameter score. In addition, transepidermal water loss, skin dryness and irritation, and quality of life (Melasma Quality of Life Scale [MelasQoL]) were evaluated. After 16 weeks, a significant decrease was noted in the degree of pigmentation based on the patients' MASI and mexameter scores. MelasQoL scores also decreased, indicating an increase in the subjects' quality of life. Our data indicate that C'ensil is an effective treatment modality for melasma.

  18. Inhibition of AcpA phosphatase activity with ascorbate attenuates Francisella tularensis intramacrophage survival.

    Science.gov (United States)

    McRae, Steven; Pagliai, Fernando A; Mohapatra, Nrusingh P; Gener, Alejandro; Mahmou, Asma Sayed Abdelgeliel; Gunn, John S; Lorca, Graciela L; Gonzalez, Claudio F

    2010-02-19

    Acid phosphatase activity in the highly infectious intracellular pathogen Francisella tularensis is directly related with the ability of these bacteria to survive inside host cells. Pharmacological inactivation of acid phosphatases could potentially help in the treatment of tularemia or even be utilized to neutralize the infection. In the present work, we report inhibitory compounds for three of the four major acid phosphatases produced by F. tularensis SCHU4: AcpA, AcpB, and AcpC. The inhibitors were identified using a catalytic screen from a library of chemicals approved for use in humans. The best results were obtained against AcpA. The two compounds identified, ascorbate (K(i) = 380 +/- 160 microM) and 2-phosphoascorbate (K(i) = 3.2 +/- 0.85 microM) inhibit AcpA in a noncompetitive, nonreversible fashion. A potential ascorbylation site in the proximity of the catalytic pocket of AcpA was identified using site-directed mutagenesis. The effects of the inhibitors identified in vitro were evaluated using bioassays determining the ability of F. tularensis to survive inside infected cells. The presence of ascorbate or 2-phosphoascorbate impaired the intramacrophage survival of F. tularensis in an AcpA-dependent manner as it was probed using knockout strains. The evidence presented herein indicated that ascorbate could be a good alternative to be used clinically to improve treatments against tularemia.

  19. Mangifera indica L. extract (Vimang) inhibits 2-deoxyribose damage induced by Fe (III) plus ascorbate.

    Science.gov (United States)

    Pardo-Andreu, Gilberto Lázaro; Delgado, René; Núñez-Sellés, Alberto J; Vercesi, Anibal E

    2006-02-01

    Vimang is an aqueous extract of selected species of Mangifera indica L, used in Cuba as a nutritional antioxidant supplement. Many in vitro and in vivo models of oxidative stress have been used to elucidate the antioxidant mechanisms of this extract. To further characterize the mechanism of Vimang action, its effect on the degradation of 2-deoxyribose induced by Fe (III)-EDTA plus ascorbate or plus hypoxanthine/xanthine oxidase was studied. Vimang was shown to be a potent inhibitor of 2-deoxyribose degradation mediated by Fe (III)-EDTA plus ascorbate or superoxide (O2-). The results revealed that Vimang, at concentrations higher than 50 microM mangiferin equivalent, was equally effective in preventing degradation of both 15 mM and 1.5 mM 2-deoxyribose. At a fixed Fe (III) concentration, increasing the concentration of ligands (either EDTA or citrate) caused a significant reduction in the protective effects of Vimang. When ascorbate was replaced by O2- (formed by hypoxanthine and xanthine oxidase) the protective efficiency of Vimang was also inversely related to EDTA concentration. The results strongly indicate that Vimang does not block 2-deoxyribose degradation by simply trapping *OH radicals. Rather, Vimang seems to act as an antioxidant by complexing iron ions, rendering them inactive or poorly active in the Fenton reaction. Copyright 2006 John Wiley & Sons, Ltd.

  20. Catalytic Therapy of Cancer with Ascorbate and Extracts of Medicinal Herbs

    Directory of Open Access Journals (Sweden)

    Nadejda Rozanova (Torshina

    2010-01-01

    Full Text Available Catalytic therapy (CT is a cancer treatment modality based on the generation of reactive oxygen species (ROS using a combination of substrate molecules and a catalyst. The most frequently used substrate/catalyst pair is ascorbate/Co phthalocyanine (PcCo. In the present work, herb extracts containing pigments have been studied as a catalyst in place of PcCo. Extracts from herbs are expected to have efficiency comparable with that of phthalocyanines but as natural products, to exhibit fewer side effects. The present studies demonstrate that a combined use of ascorbate and herbal extracts results in ROS production and a significant decrease in the number of cancer cells after a single in vitro treatment. Treatment with ascorbate in conjunction with extracts prepared from several medicinal herbs stimulated apoptosis and disrupted the cell cycle. The number of cells accumulating in the sub-G0/G1 stage of the cell cycle was increased 2- to 7-fold, and cells in G2/M increased 1.5- to 20-fold, indicating that the treatment protocol was highly effective in suppressing DNA synthesis and potentially reflecting DNA damage in the tumor cells. In addition, 20–40% of the cells underwent apoptosis within 24 h of completing treatment. Our results suggest that herbal extracts can function as CT catalysts in the treatment of cancer.

  1. Characteristic of ascorbic acid in crosslinked chitosan edible film as drug delivery system membrane

    Directory of Open Access Journals (Sweden)

    Kistriyani Lilis

    2018-01-01

    Full Text Available Chitosan is a polysaccharide compound in the form of a linear polysaccharide consisting of N-acetyl glucosamine (GlcNAc and D-glucosamine (GlcN monomer, which is a derivative of deacetylization of chitin polymer. Chitin is one of common type of polysaccharide on earth after the excess cellulose from inveterbrata skeletons. Chitosan has anti-microbial properties. Based on this properties, chitosan is potentially used to be an edible film as drug delivery system membrane. Edible film was made by dissolving chitosan in 100 mL acetic acid 1%, then the plasticizer and crosslinker was added while heated at 60° C. It was molded and dried in oven at 50°C for 48 hours. Drug loading in the edible film could be controlled by remodeling membrane characteristics in the presence of crosslinker additions. The purpose of this study was to estimate the mass transfer coefficient (kCa of drug loading in various concentrations of ascorbic acid in the edible film. The characteristics of ascorbic acid in chitosan edible film could be seen from the number of drugs that could be loaded through the uv-vis spectrophotometric analysis. The higher concentration of ascorbic acid was added, the drug would be loaded more into edible film.

  2. Seasonal profiles of leaf ascorbic acid content and redox state in ozone-sensitive wildflowers

    International Nuclear Information System (INIS)

    Burkey, Kent O.; Neufeld, Howard S.; Souza, Lara; Chappelka, Arthur H.; Davison, Alan W.

    2006-01-01

    Cutleaf coneflower (Rudbeckia laciniata L.), crown-beard (Verbesina occidentalis Walt.), and tall milkweed (Asclepias exaltata L.) are wildflower species native to Great Smoky Mountains National Park (U.S.A.). Natural populations of each species were analyzed for leaf ascorbic acid (AA) and dehydroascorbic acid (DHA) to assess the role of ascorbate in protecting the plants from ozone stress. Tall milkweed contained greater quantities of AA (7-10 μmol g -1 fresh weight) than crown-beard (2-4 μmol g -1 fresh weight) or cutleaf coneflower (0.5-2 μmol g -1 fresh weight). DHA was elevated in crown-beard and cutleaf coneflower relative to tall milkweed suggesting a diminished capacity for converting DHA into AA. Tall milkweed accumulated AA in the leaf apoplast (30-100 nmol g -1 fresh weight) with individuals expressing ozone foliar injury symptoms late in the season having less apoplast AA. In contrast, AA was not present in the leaf apoplast of either crown-beard or cutleaf coneflower. Unidentified antioxidant compounds were present in the leaf apoplast of all three species. Overall, distinct differences in antioxidant metabolism were found in the wildflower species that corresponded with differences in ozone sensitivity. - Wildflower species exhibit differences in ascorbic acid content and redox status that affect ozone sensitivity

  3. Seasonal profiles of leaf ascorbic acid content and redox state in ozone-sensitive wildflowers

    Energy Technology Data Exchange (ETDEWEB)

    Burkey, Kent O. [Plant Science Research Unit, USDA-ARS and North Carolina State University, 3127 Ligon Street, Raleigh, NC 27607 (United States)]. E-mail: koburkey@unity.ncsu.edu; Neufeld, Howard S. [Appalachian State University, Boone, NC (United States); Souza, Lara [Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN (United States); Chappelka, Arthur H. [Auburn University, Auburn, AL (United States); Davison, Alan W. [University of Newcastle, Newcastle, England (United Kingdom)

    2006-10-15

    Cutleaf coneflower (Rudbeckia laciniata L.), crown-beard (Verbesina occidentalis Walt.), and tall milkweed (Asclepias exaltata L.) are wildflower species native to Great Smoky Mountains National Park (U.S.A.). Natural populations of each species were analyzed for leaf ascorbic acid (AA) and dehydroascorbic acid (DHA) to assess the role of ascorbate in protecting the plants from ozone stress. Tall milkweed contained greater quantities of AA (7-10 {mu}mol g{sup -1} fresh weight) than crown-beard (2-4 {mu}mol g{sup -1} fresh weight) or cutleaf coneflower (0.5-2 {mu}mol g{sup -1} fresh weight). DHA was elevated in crown-beard and cutleaf coneflower relative to tall milkweed suggesting a diminished capacity for converting DHA into AA. Tall milkweed accumulated AA in the leaf apoplast (30-100 nmol g{sup -1} fresh weight) with individuals expressing ozone foliar injury symptoms late in the season having less apoplast AA. In contrast, AA was not present in the leaf apoplast of either crown-beard or cutleaf coneflower. Unidentified antioxidant compounds were present in the leaf apoplast of all three species. Overall, distinct differences in antioxidant metabolism were found in the wildflower species that corresponded with differences in ozone sensitivity. - Wildflower species exhibit differences in ascorbic acid content and redox status that affect ozone sensitivity.

  4. Ascorbic acid interference in the measurement of serum biochemical parameters: in vivo and in vitro studies.

    Science.gov (United States)

    Martinello, Flávia; da Silva, Edson Luiz

    2006-04-01

    To investigate the negative interference of ascorbic acid in serum biochemical tests in relation to the dose of vitamin C intake and to the time of blood collection. Healthy volunteers (n = 18) consumed daily doses of vitamin C (0.25-4.0 g) for 1 week and serum parameters were assayed prior to the experiment and on the eighth day of consumption. Blood samples were collected 4, 12 and 24 h after vitamin C intake. Serum levels of ascorbic acid increased significantly after vitamin C ingestion inhibiting urate and total bilirubin tests 4 and 12 h after intake (P cholesterol tests. Addition of ascorbic acid to serum inhibited the urate test to a similar extent to that observed after vitamin C intake. However, after ingesting vitamin C, the interference for the bilirubin test was greater than that of the in vitro interference. Commonly taken doses of supplementary vitamin C interfered negatively with the serum urate test based on the Trinder method, and with bilirubin metabolism.

  5. Radioprotection potential of the ascorbic acid on the carrageenan used as food additive

    International Nuclear Information System (INIS)

    Aliste, Antonio Joao; Mastro, Nelida Lucia del

    2002-01-01

    Carrageenans are a group of natural carbohydrates that are present in the structure of certain varieties of red algae (Rhodophyceae). They are used in emulsions, for syneresis control and to grow up, to promote adhesiveness and dispersion. In the industry of foods they can be used for instance, as thickness and gelling agents, alone or together with other additives. The processing of foods by radiation is increasing considerably, because the efficiency of the process in the industrial decontamination of products. The objective of this work was to study the action of the ascorbic acid as potential radioprotector of the carrageenan against 60 Co gamma radiation effects, using the viscosity as parameter. Samples of commercial carrageenan dissolved at 1,0% were irradiated in the presence or not of ascorbic acid, with doses of 0.0 kGy; 1.0 kGy; 2.5 kGy; 5.0 kGy and 10.0 kGy. After the irradiation the relationships viscosity/dose were established for the temperature of 60 deg C. For the dose of 10.0 kGy a better protecting effect of the ascorbic acid on the carrageenan was seen. The implications of the use of this antioxidant is discussed as a form of minimizing the effect of the radiation in irradiated foods. (author)

  6. Matrix Metalloproteinase Enzyme Family

    Directory of Open Access Journals (Sweden)

    Ozlem Goruroglu Ozturk

    2013-04-01

    Full Text Available Matrix metalloproteinases play an important role in many biological processes such as embriogenesis, tissue remodeling, wound healing, and angiogenesis, and in some pathological conditions such as atherosclerosis, arthritis and cancer. Currently, 24 genes have been identified in humans that encode different groups of matrix metalloproteinase enzymes. This review discuss the members of the matrix metalloproteinase family and their substrate specificity, structure, function and the regulation of their enzyme activity by tissue inhibitors. [Archives Medical Review Journal 2013; 22(2.000: 209-220

  7. Inhibition of cell proliferation and migration by oxidative stress from ascorbate-driven juglone redox cycling in human bladder-derived T24 cells

    Energy Technology Data Exchange (ETDEWEB)

    Kviecinski, M.R., E-mail: mrkviecinski@hotmail.com [Laboratorio de Bioquimica Experimental, Departamento de Bioquimica, Universidade Federal de Santa Catarina, Florianopolis (Brazil); Pedrosa, R.C., E-mail: rozangelapedrosa@gmail.com [Laboratorio de Bioquimica Experimental, Departamento de Bioquimica, Universidade Federal de Santa Catarina, Florianopolis (Brazil); Felipe, K.B., E-mail: kakabettega@yahoo.com.br [Laboratorio de Bioquimica Experimental, Departamento de Bioquimica, Universidade Federal de Santa Catarina, Florianopolis (Brazil); Farias, M.S., E-mail: mirellesfarias@hotmail.com [Laboratorio de Bioquimica Experimental, Departamento de Bioquimica, Universidade Federal de Santa Catarina, Florianopolis (Brazil); Glorieux, C., E-mail: christophe.glorieux@uclouvain.be [Toxicology and Cancer Biology Research Group, Louvain Drug Research Institute, Universite Catholique de Louvain, 73 Avenue E. Mounier, GTOX 7309, 1200 Brussels (Belgium); Valenzuela, M., E-mail: mavalenzuela@med.uchile.cl [Toxicology and Cancer Biology Research Group, Louvain Drug Research Institute, Universite Catholique de Louvain, 73 Avenue E. Mounier, GTOX 7309, 1200 Brussels (Belgium); Sid, B., E-mail: brice.sid@uclouvain.be [Toxicology and Cancer Biology Research Group, Louvain Drug Research Institute, Universite Catholique de Louvain, 73 Avenue E. Mounier, GTOX 7309, 1200 Brussels (Belgium); and others

    2012-05-04

    Highlights: Black-Right-Pointing-Pointer The cytotoxicity of juglone is markedly increased by ascorbate. Black-Right-Pointing-Pointer T24 cell death by oxidative stress is necrosis-like. Black-Right-Pointing-Pointer Redox cycling by juglone/ascorbate inhibits cell proliferation. Black-Right-Pointing-Pointer Cellular migration is impaired by juglone/ascorbate. -- Abstract: The effects of juglone on T24 cells were assessed in the presence and absence of ascorbate. The EC{sub 50} value for juglone at 24 h decreased from 28.5 {mu}M to 6.3 {mu}M in the presence of ascorbate. In juglone-treated cells, ascorbate increased ROS formation (4-fold) and depleted GSH (65%). N-acetylcysteine or catalase restricted the juglone/ascorbate-mediated effects, highlighting the role of oxidative stress in juglone cytotoxicity. Juglone alone or associated with ascorbate did not cause caspase-3 activation or PARP cleavage, suggesting necrosis-like cell death. DNA damage and the mild ER stress caused by juglone were both enhanced by ascorbate. In cells treated with juglone (1-5 {mu}M), a concentration-dependent decrease in cell proliferation was observed. Ascorbate did not impair cell proliferation but its association with juglone led to a clonogenic death state. The motility of ascorbate-treated cells was not affected. Juglone slightly restricted motility, but cells lost their ability to migrate most noticeably when treated with juglone plus ascorbate. We postulate that juglone kills cells by a necrosis-like mechanism inhibiting cell proliferation and the motility of T24 cells. These effects are enhanced in the presence of ascorbate.

  8. Physico-mechanical analysis data in support of compatibility of chitosan/κ-carrageenan polyelectrolyte films achieved by ascorbic acid, and the thermal degradation theory of κ-carrageenan influencing the properties of its blends

    Directory of Open Access Journals (Sweden)

    Mahdiyar Shahbazi

    2016-12-01

    Full Text Available This article presents the complementary data regarding compatibilization of chitosan/κ-carrageenan polyelectrolyte complex for synthesizing of a soft film using ascorbic acid. It includes the thermal-theory for estimating the degradation of κ-carrageenan, as reflected in alteration of the structural properties of the blend. The data has been provided to demonstrate that the blend solution based on chitosan, a polycation, and κ-carrageenan, a polyanion polymer, produces an incompatible polyelectrolyte composite, susceptible to coaservative phase separation. We present further data on water resistance, water barrier property, mechanical parameters, scanning electron micrograph, as well as contact angle image dataset of the chitosan/κ-carrageenan film. The physical data were collected by water solubility and water permeability assays, with a view to elucidate the role of ascorbic acid in the compatibility of polyelectrolyte blends. The mechanical data is obtained from a stress–strain curve for evaluation of tensile strength and elongation at break point of the chitosan/κ-carrageenan film. The microstructure observations were performed using scanning electron micrograph. These dataset confirm fabrication of a soft film in the presence of ascorbic acid, with reduced heterogeneities in the polyelectrolyte film structure. The κ-carrageenan was also treated by a thermal process, prior to inclusion into the chitosan solution, to investigate the impact of this on the mechanical and structural features of the resulting blend. We present the required data and the theoretical analysis supporting the thermal chain degradation of a polymer and its effects on behavior of the film. Additional information, characterizing the hydrophobicity of the surface of the blend layers is obtained by measuring water contact angles using a contact anglemeter.

  9. The surface science of enzymes

    DEFF Research Database (Denmark)

    Rod, Thomas Holm; Nørskov, Jens Kehlet

    2002-01-01

    One of the largest challenges to science in the coming years is to find the relation between enzyme structure and function. Can we predict which reactions an enzyme catalyzes from knowledge of its structure-or from its amino acid sequence? Can we use that knowledge to modify enzyme function......? To solve these problems we must understand in some detail how enzymes interact with reactants from its surroundings. These interactions take place at the surface of the enzyme and the question of enzyme function can be viewed as the surface science of enzymes. In this article we discuss how to describe...... catalysis by enzymes, and in particular the analogies between enzyme catalyzed reactions and surface catalyzed reactions. We do this by discussing two concrete examples of reactions catalyzed both in nature (by enzymes) and in industrial reactors (by inorganic materials), and show that although analogies...

  10. Improvement of bioavailability for iron from vegetarian meals by ascorbic acid

    International Nuclear Information System (INIS)

    Sritongkul, N.; Tuntawiroon, M.; Pleehachinda, R.; Suwanik, R.

    1996-01-01

    There are two kinds of iron in the diet with respect to the mechanism of absorption, heme-iron which is present as haemoglobin or myoglobin in meat and blood products, and, non-heme iron which is the main source of dietary iron. The bioavailability of the non-heme food iron is much lower than heme-iron. Vegetarian diets contain only non-heme iron. Iron intake from vegetarian meals are generally satisfied with the requirements, however, the bioavailabilities for non-heme iron is determined not only by iron content byt also the balance between different dietary factors enhancing and inhibiting iron absorption. The main enhancing factor in vegetarian meals is ascorbic acid in fruits and vegetables, inhibitors are phytate in cereals and grains, and tannins in some spices and vegetables. It has been reported that iron deficiency is one of the common micronutrient problems associated with unplanned vegetarian diets. In the present study the absorption of non-heme iron was measured from 2 vegetarian meals containing considerable amounts of phytate and tannin. The extrinsic tay method ( 59 Fe/ 55 Fe) was used to labelled the non-heme iron. The mean percentage absorption of non-heme iron from both meals was slightly different due to differences in their dietary contents. Their initial percentages iron absorption were apparent low (3.5% and 4.1%), however, the absorption progressively increased with increase in the level of ascorbic acid, 2-3 times with 100 mg and 4-5 times with 200 mg of ascorbic acid. The average amount of iron absorbed per 2000 kcal increased from 0.37 mg to 0.86 mg and 1.45 mg with the addition of 100 mg and 200 mg ascorbic acid respectively (p < 0.001). Considering the limited caloric intakes and the iron content in the meals, the amount of iron absorbed from vegetarian meals without ascorbic acid was not able to meet certain requirements for children, adolescents and menstruating women. The minimal requirement for dietary iron needed to be absorbed is

  11. Direct electrodeposition of gold nanotube arrays of rough and porous wall by cyclic voltammetry and its applications of simultaneous determination of ascorbic acid and uric acid

    Energy Technology Data Exchange (ETDEWEB)

    Yang Guangming, E-mail: yangguangmingbs@126.com [Department of Resources and Environment, Baoshan University, Baoshan 678000 (China); Ling, Li [Department of Resources and Environment, Baoshan University, Baoshan 678000 (China); Jinhe, Jiang; Yunhui, Yang [College of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming 650092 (China)

    2012-08-01

    Gold nanotube arrays of rough and porous wall has been synthesized by direct electrodeposition with cyclic voltammetry utilizing anodic aluminum oxide template (AAO) and polycarbonate membrane (PC) during short time (only 3 min and 2 min, respectively). The mechanism of the direct electrodeposition of gold nanotube arrays by cyclic voltammetry (CV) has been discussed. The morphological characterizations of the gold nanotube arrays have been investigated by scanning electron microscopy (SEM). A simultaneous determination of ascorbic acid (AA) and uric acid (UA) by differential pulse voltammetry (DPV) was constructed by attaching gold nanotube arrays (using AAO) onto the surface of a glassy carbon electrode (GCE). The electrochemical behavior of AA and UA at this modified electrode has been studied by CV and differential pulse voltammetry (DPV). The sensor offers an excellent response for AA and UA and the linear response range for AA and UA were 1.02 Multiplication-Sign 10{sup -7}-5.23 Multiplication-Sign 10{sup -4} mol L{sup -1} and 1.43 Multiplication-Sign 10{sup -7}-4.64 Multiplication-Sign 10{sup -4} mol L{sup -1}, the detection limits were 1.12 Multiplication-Sign 10{sup -8} mol L{sup -1} and 2.24 Multiplication-Sign 10{sup -8} mol L{sup -1}, respectively. This sensor shows good regeneration, stability and selectivity and has been used for the determination of AA and UA in real human urine and serum samples with satisfied results. - Graphical abstract: The schematic diagram of formation of Au nanotube arrays (a) and the stepwise procedure of the sensor (b). Highlights: Black-Right-Pointing-Pointer Gold nanotubes array has been synthesized by cyclic voltammetry. Black-Right-Pointing-Pointer The mechanism of deposition of gold nanotube has been discussed. Black-Right-Pointing-Pointer A determination of ascorbic acid and uric acid was constructed by gold array. Black-Right-Pointing-Pointer A satisfied determination of samples can be obtained by this sensor.

  12. Magnetically responsive enzyme powders

    Czech Academy of Sciences Publication Activity Database

    Pospišková, K.; Šafařík, Ivo

    2015-01-01

    Roč. 380, APR 2015 (2015), s. 197-200 ISSN 0304-8853 R&D Projects: GA MŠk(CZ) LD13021 Institutional support: RVO:67179843 Keywords : enzyme powders * cross-linking * magnetic modification * magnetic separation * magnetic iron oxides particles * microwave-assisted synthesis Subject RIV: CE - Biochemistry Impact factor: 2.357, year: 2015

  13. Enzyme with rhamnogalacturonase activity.

    NARCIS (Netherlands)

    Kofod, L.V.; Andersen, L.N.; Dalboge, H.; Kauppinen, M.S.; Christgau, S.; Heldt-Hansen, H.P.; Christophersen, C.; Nielsen, P.M.; Voragen, A.G.J.; Schols, H.A.

    1998-01-01

    An enzyme exhibiting rhamnogalacturonase activity, capable of cleaving a rhamnogalacturonan backbone in such a manner that galacturonic acids are left as the non-reducing ends, and which exhibits activity on hairy regions from a soy bean material and/or on saponified hairy regions from a sugar beet

  14. Implantable enzyme amperometric biosensors.

    Science.gov (United States)

    Kotanen, Christian N; Moussy, Francis Gabriel; Carrara, Sandro; Guiseppi-Elie, Anthony

    2012-05-15

    The implantable enzyme amperometric biosensor continues as the dominant in vivo format for the detection, monitoring and reporting of biochemical analytes related to a wide range of pathologies. Widely used in animal studies, there is increasing emphasis on their use in diabetes care and management, the management of trauma-associated hemorrhage and in critical care monitoring by intensivists in the ICU. These frontier opportunities demand continuous indwelling performance for up to several years, well in excess of the currently approved seven days. This review outlines the many challenges to successful deployment of chronically implantable amperometric enzyme biosensors and emphasizes the emerging technological approaches in their continued development. The foreign body response plays a prominent role in implantable biotransducer failure. Topics considering the approaches to mitigate the inflammatory response, use of biomimetic chemistries, nanostructured topographies, drug eluting constructs, and tissue-to-device interface modulus matching are reviewed. Similarly, factors that influence biotransducer performance such as enzyme stability, substrate interference, mediator selection and calibration are reviewed. For the biosensor system, the opportunities and challenges of integration, guided by footprint requirements, the limitations of mixed signal electronics, and power requirements, has produced three systems approaches. The potential is great. However, integration along the multiple length scales needed to address fundamental issues and integration across the diverse disciplines needed to achieve success of these highly integrated systems, continues to be a challenge in the development and deployment of implantable amperometric enzyme biosensor systems. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Advances in enzyme bioelectrochemistry

    Directory of Open Access Journals (Sweden)

    ANDRESSA R. PEREIRA

    Full Text Available ABSTRACT Bioelectrochemistry can be defined as a branch of Chemical Science concerned with electron-proton transfer and transport involving biomolecules, as well as electrode reactions of redox enzymes. The bioelectrochemical reactions and system have direct impact in biotechnological development, in medical devices designing, in the behavior of DNA-protein complexes, in green-energy and bioenergy concepts, and make it possible an understanding of metabolism of all living organisms (e.g. humans where biomolecules are integral to health and proper functioning. In the last years, many researchers have dedicated itself to study different redox enzymes by using electrochemistry, aiming to understand their mechanisms and to develop promising bioanodes and biocathodes for biofuel cells as well as to develop biosensors and implantable bioelectronics devices. Inside this scope, this review try to introduce and contemplate some relevant topics for enzyme bioelectrochemistry, such as the immobilization of the enzymes at electrode surfaces, the electron transfer, the bioelectrocatalysis, and new techniques conjugated with electrochemistry vising understand the kinetics and thermodynamics of redox proteins. Furthermore, examples of recent approaches in designing biosensors and biofuel developed are presented.

  16. Cold-Adapted Enzymes

    Science.gov (United States)

    Georlette, D.; Bentahir, M.; Claverie, P.; Collins, T.; D'amico, S.; Delille, D.; Feller, G.; Gratia, E.; Hoyoux, A.; Lonhienne, T.; Meuwis, M.-a.; Zecchinon, L.; Gerday, Ch.

    In the last few years, increased attention has been focused on enzymes produced by cold-adapted micro-organisms. It has emerged that psychrophilic enzymes represent an extremely powerful tool in both protein folding investigations and for biotechnological purposes. Such enzymes are characterised by an increased thermosensitivity and, most of them, by a higher catalytic efficiency at low and moderate temperatures, when compared to their mesophilic counterparts. The high thermosensitivity probably originates from an increased flexibility of either a selected area of the molecular edifice or the overall protein structure, providing enhanced abilities to undergo conformational changes during catalysis at low temperatures. Structure modelling and recent crystallographic data have allowed to elucidate the structural parameters that could be involved in this higher resilience. It was demonstrated that each psychrophilic enzyme adopts its own adaptive strategy. It appears, moreover, that there is a continuum in the strategy of protein adaptation to temperature, as the previously mentioned structural parameters are implicated in the stability of thermophilic proteins. Additional 3D crystal structures, site-directed and random mutagenesis experiments should now be undertaken to further investigate the stability-flexibility-activity relationship.

  17. Embedded enzymes catalyse capture

    Science.gov (United States)

    Kentish, Sandra

    2018-05-01

    Membrane technologies for carbon capture can offer economic and environmental advantages over conventional amine-based absorption, but can suffer from limited gas flux and selectivity to CO2. Now, a membrane based on enzymes embedded in hydrophilic pores is shown to exhibit combined flux and selectivity that challenges the state of the art.

  18. Photoperiodism and Enzyme Activity

    Science.gov (United States)

    Queiroz, Orlando; Morel, Claudine

    1974-01-01

    Metabolic readjustments after a change from long days to short days appear, in Kalanchoe blossfeldiana, to be achieved through the operation of two main mechanisms: variation in enzyme capacity, and circadian rhythmicity. After a lag time, capacity in phosphoenolpyruvate carboxylase and capacity in aspartate aminotransferase increase exponentially and appear to be allometrically linked during 50 to 60 short days; then a sudden fall takes place in the activity of the former. Malic enzyme and alanine aminotransferase behave differently. Thus, the operation of the two sections of the pathway (before and after the malate step) give rise to a continuously changing functional compartmentation in the pathway. Circadian rhythmicity, on the other hand, produces time compartmentation through phase shifts and variation in amplitude, independently for each enzyme. These characteristics suggest that the operation of a so-called biological clock would be involved. We propose the hypothesis that feedback regulation would be more accurate and efficient when applied to an already oscillating, clock-controlled enzyme system. PMID:16658749

  19. ISFET based enzyme sensors

    NARCIS (Netherlands)

    van der Schoot, Bart H.; Bergveld, Piet

    1987-01-01

    This paper reviews the results that have been reported on ISFET based enzyme sensors. The most important improvement that results from the application of ISFETs instead of glass membrane electrodes is in the method of fabrication. Problems with regard to the pH dependence of the response and the

  20. Influence of secretagogues on asynchronous secretion of newly synthesized pancreatic proteins in the conscious rat

    International Nuclear Information System (INIS)

    Keim, V.; Rohr, G.

    1987-01-01

    The secretion of newly synthesized pancreatic enzymes was studied in pancreatic duct cannulated rats after intravenous injection of 100 microCi of [ 35 S]methionine. Secretion rate was stimulated by intravenous infusion of either cerulein (0.2 microgram/kg h) or carbachol (10 nmol/kg h) starting simultaneously with or 180 min before the injection of the labeled methionine. Secretory proteins were analyzed by sodium dodecyl sulfate (SDS) gel electrophoresis or by nondenaturing gel electrophoresis followed by determination of the radioactivity associated with the individual proteins. Similar to unstimulated controls in all experiments, an early secretion of newly synthesized trypsinogen and chymotrypsinogen was found, whereas amylase and lipase were secreted only after a certain lag period. The results suggest that the intracellular transit of endoproteases is faster than that of other enzymes, irrespective of whether or not secretagogues were applied

  1. Increase in tartrate-resistant acid phosphatase of bone at the early stage of ascorbic acid deficiency in the ascorbate-requiring Osteogenic Disorder Shionogi (ODS) rat.

    Science.gov (United States)

    Goto, A; Tsukamoto, I

    2003-08-01

    The effect of ascorbic acid deficiency on bone metabolism was evaluated using the ascorbate-requiring Osteogenic Disorder Shionogi (ODS) rat model. Ascorbic acid (Asc)-deficient rats gained body weight in a manner similar to Asc-supplemented rats (control) during 3 weeks, but began to lose weight during the 4th week of Asc deficiency. The tartrate-resistant acid phosphatase (TRAP) activity in serum increased to about 2-fold the control value in the rats fed the Asc-free diet for 2, 3, and 4 weeks (AscD2, AscD3, and AscD4), while a decrease in the alkaline phosphatase (ALP) activity was observed only in AscD4 rats. The serum pyridinoline cross-linked carboxyterminal telopeptide of type I collagen (ICTP) level significantly increased to 1.3-, 1.4-, and 1.9-fold of that in the controls in AscD2, D3, and D4, respectively. The ALP activity in the distal femur was unchanged in AscD1, D2, and D3, but decreased to 50% of the control level in AscD4 rats. The TRAP activity in the distal femur increased to about 2-fold of that in the controls in the AscD2 and D3 and decreased to the control level in the AscD4 rats. The amount of hydroxyproline in the distal femur significantly decreased to about 80%, 70%, and 60% of the control in AscD2, D3, and D4 rats, respectively. These decreases were associated with a similar reduction in the calcium content of the distal femur. Histochemical analysis of the distal femur showed an increase in TRAP-positive cells in AscD2 and AscD3 rats and a decrease in the trabecular bone in AscD2, D3, and D4 rats. These results suggested that a deficiency of Asc stimulated bone resorption at an early stage, followed by a decrease in bone formation in mature ODS rats which already had a well-developed collagen matrix and fully differentiated osteoblasts.

  2. The Enzyme Function Initiative†

    Science.gov (United States)

    Gerlt, John A.; Allen, Karen N.; Almo, Steven C.; Armstrong, Richard N.; Babbitt, Patricia C.; Cronan, John E.; Dunaway-Mariano, Debra; Imker, Heidi J.; Jacobson, Matthew P.; Minor, Wladek; Poulter, C. Dale; Raushel, Frank M.; Sali, Andrej; Shoichet, Brian K.; Sweedler, Jonathan V.

    2011-01-01

    The Enzyme Function Initiative (EFI) was recently established to address the challenge of assigning reliable functions to enzymes discovered in bacterial genome projects; in this Current Topic we review the structure and operations of the EFI. The EFI includes the Superfamily/Genome, Protein, Structure, Computation, and Data/Dissemination Cores that provide the infrastructure for reliably predicting the in vitro functions of unknown enzymes. The initial targets for functional assignment are selected from five functionally diverse superfamilies (amidohydrolase, enolase, glutathione transferase, haloalkanoic acid dehalogenase, and isoprenoid synthase), with five superfamily-specific Bridging Projects experimentally testing the predicted in vitro enzymatic activities. The EFI also includes the Microbiology Core that evaluates the in vivo context of in vitro enzymatic functions and confirms the functional predictions of the EFI. The deliverables of the EFI to the scientific community include: 1) development of a large-scale, multidisciplinary sequence/structure-based strategy for functional assignment of unknown enzymes discovered in genome projects (target selection, protein production, structure determination, computation, experimental enzymology, microbiology, and structure-based annotation); 2) dissemination of the strategy to the community via publications, collaborations, workshops, and symposia; 3) computational and bioinformatic tools for using the strategy; 4) provision of experimental protocols and/or reagents for enzyme production and characterization; and 5) dissemination of data via the EFI’s website, enzymefunction.org. The realization of multidisciplinary strategies for functional assignment will begin to define the full metabolic diversity that exists in nature and will impact basic biochemical and evolutionary understanding, as well as a wide range of applications of central importance to industrial, medicinal and pharmaceutical efforts. PMID

  3. The Enzyme Function Initiative.

    Science.gov (United States)

    Gerlt, John A; Allen, Karen N; Almo, Steven C; Armstrong, Richard N; Babbitt, Patricia C; Cronan, John E; Dunaway-Mariano, Debra; Imker, Heidi J; Jacobson, Matthew P; Minor, Wladek; Poulter, C Dale; Raushel, Frank M; Sali, Andrej; Shoichet, Brian K; Sweedler, Jonathan V

    2011-11-22

    The Enzyme Function Initiative (EFI) was recently established to address the challenge of assigning reliable functions to enzymes discovered in bacterial genome projects; in this Current Topic, we review the structure and operations of the EFI. The EFI includes the Superfamily/Genome, Protein, Structure, Computation, and Data/Dissemination Cores that provide the infrastructure for reliably predicting the in vitro functions of unknown enzymes. The initial targets for functional assignment are selected from five functionally diverse superfamilies (amidohydrolase, enolase, glutathione transferase, haloalkanoic acid dehalogenase, and isoprenoid synthase), with five superfamily specific Bridging Projects experimentally testing the predicted in vitro enzymatic activities. The EFI also includes the Microbiology Core that evaluates the in vivo context of in vitro enzymatic functions and confirms the functional predictions of the EFI. The deliverables of the EFI to the scientific community include (1) development of a large-scale, multidisciplinary sequence/structure-based strategy for functional assignment of unknown enzymes discovered in genome projects (target selection, protein production, structure determination, computation, experimental enzymology, microbiology, and structure-based annotation), (2) dissemination of the strategy to the community via publications, collaborations, workshops, and symposia, (3) computational and bioinformatic tools for using the strategy, (4) provision of experimental protocols and/or reagents for enzyme production and characterization, and (5) dissemination of data via the EFI's Website, http://enzymefunction.org. The realization of multidisciplinary strategies for functional assignment will begin to define the full metabolic diversity that exists in nature and will impact basic biochemical and evolutionary understanding, as well as a wide range of applications of central importance to industrial, medicinal, and pharmaceutical efforts.

  4. High Sensitivity Electrochemical Cholesterol Sensor Utilizing a Vertically Aligned Carbon Nanotube Electrode with Electropolymerized Enzyme Immobilization

    Directory of Open Access Journals (Sweden)

    Ditsayut Phokharatkul

    2009-10-01

    Full Text Available In this report, a new cholesterol sensor is developed based on a vertically aligned CNT electrode with two-step electrochemical polymerized enzyme immobilization. Vertically aligned CNTs are selectively grown on a 1 mm2 window of gold coated SiO2/Si substrate by thermal chemical vapor deposition (CVD with gravity effect and water-assisted etching. CNTs are then simultaneously functionalized and enzyme immobilized by electrochemical polymerization of polyaniline and cholesterol enzymes. Subsequently, ineffective enzymes are removed and new enzymes are electrochemically recharged. Scanning electron microscopic characterization indicates polymer-enzyme nanoparticle coating on CNT surface. Cyclic voltammogram (CV measurements in cholesterol solution show the oxidation and reduction peaks centered around 450 and −220 mV, respectively. An approximately linear relationship between the cholesterol concentration and the response current could be observed in the concentration range of 50–300 mg/dl with a sensitivity of approximately 0.22 μA/mg·dl−1, which is considerably higher compared to previously reported CNT bioprobe. In addition, good specificity toward glucose, uric acid acetaminophen and ascorbic acid have been obtained. Moreover, sensors have satisfactory stability, repeatability and life time. Therefore, the electropolymerized CNT bioprobe is promising for cholesterol detection in normal cholesterol concentration in human blood.

  5. Induction of antioxidant enzyme activity and lipid peroxidation level in ion-beam-bombarded rice seeds

    Science.gov (United States)

    Semsang, Nuananong; Yu, LiangDeng

    2013-07-01

    Low-energy ion beam bombardment has been used to mutate a wide variety of plant species. To explore the indirect effects of low-energy ion beam on biological damage due to the free radical production in plant cells, the increase in antioxidant enzyme activities and lipid peroxidation level was investigated in ion-bombarded rice seeds. Local rice seeds were bombarded with nitrogen or argon ion beams at energies of 29-60 keV and ion fluences of 1 × 1016 ions cm-2. The activities of the antioxidant enzymes; superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), glutathione reductase (GR), glutathione S-transferase (GST) and lipid peroxidation level were assayed in the germinated rice seeds after ion bombardment. The results showed most of the enzyme activities and lipid peroxidation levels in both the argon and nitrogen bombarded samples were higher than those in the natural control. N-ion bombardment could induce higher levels of antioxidant enzyme activities in the rice samples than the Ar-ion bombardment. Additional effects due to the vacuum condition were found to affect activities of some antioxidant enzymes and lipid peroxidation level. This study demonstrates that ion beam bombardment and vacuum condition could induce the antioxidant enzyme activity and lipid peroxidation level which might be due to free radical production in the bombarded rice seeds.

  6. Synthesizing Modular Invariants for Synchronous Code

    Directory of Open Access Journals (Sweden)

    Pierre-Loic Garoche

    2014-12-01

    Full Text Available In this paper, we explore different techniques to synthesize modular invariants for synchronous code encoded as Horn clauses. Modular invariants are a set of formulas that characterizes the validity of predicates. They are very useful for different aspects of analysis, synthesis, testing and program transformation. We describe two techniques to generate modular invariants for code written in the synchronous dataflow language Lustre. The first technique directly encodes the synchronous code in a modular fashion. While in the second technique, we synthesize modular invariants starting from a monolithic invariant. Both techniques, take advantage of analysis techniques based on property-directed reachability. We also describe a technique to minimize the synthesized invariants.

  7. Properties of Er{sub 2}O{sub 3} nanoparticles synthesized by a modified co-precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Castaneda C, J.; Maranon R, V. F.; Perez Ladron de G, H.; Rodriguez R, R. A.; Chiu Z, R. [Universidad de Guadalajara, Centro Universitario de los Lagos, Av. Enrique Diaz de Leon s/n, Lagos de Moreno 47460, Jalisco (Mexico); Meneses N, M. A., E-mail: jcc050769@yahoo.com.mx [Centro de Investigaciones en Optica, A. C., Apdo. Postal 1-948, Leon, Guanajuato (Mexico)

    2015-07-01

    Er{sub 2}O{sub 3} nanoparticles were synthesized by co-precipitation with the addition of ascorbate as stabilizing agent. The nanoparticles had spherical shapes with a mean diameter of 32 nm and were allocated in clusters, as determined by X-ray diffraction, atomic force microscopy and optical microscopy. Characteristic green and red emissions from Er{sup 3+} were recorded by pumping the nanoparticles at 525 nm, 805 nm and 975 nm. However, the luminescence spectra show an enhancement of red emission for Nir pump wavelengths. We proposed this behavior was due to phonon-assisted depopulation mechanisms and energy transfer processes related to the different excitation schemes. (Author)

  8. Evaluation of gamma irradiation effects on carotenoids, ascorbic acid and sugar contents of buriti fruit (Mauritia flexuosa L.)

    International Nuclear Information System (INIS)

    Lima, Antonio Luis dos Santos; Lima, Keila dos Santos Cople; Silva, Jaqueline Michele; Coelho, Maysa Joppert; Godoy, Ronoel Luiz de Oliveira; Pacheco, Sidney

    2009-01-01

    Buriti (Mauritia flexuosa L.), a typical fruit from the Northeast and Center-West Amazon of Brazil, is used in many regional dishes. It is considered an excellent source of carotenoids that are A vitamin precursors, showing a majority of beta-carotene. It also presents ascorbic acid and sugar contents. Many studies have indicated that the lack of A vitamin is the main cause of night blindness and xerophthalmia. Also, ascorbic acid deficiency may cause scorbutic disease. The use of food irradiation is growing and represents an economic benefit to agriculture through the reduction of post-harvesting losses while maintaining food nutritional quality. In this study, buriti in natura was treated with gamma irradiation with doses of 0.5 kGy and 1.0 kGy. The objective was to evaluate the irradiation effects on total carotenoids, ascorbic acid and sugars concentrations of buriti. The fruit was evaluated through the total carotenoids analysis, by spectrophotometry, and the carotenoids (alpha and beta-carotene and lutein), ascorbic acid and sugars were determined by high performance liquid chromatography (HPLC). The results showed that buriti is an excellent source of total carotenoids (44600 μg/100 g). The irradiation of buriti with the dose of 0.5 kGy did not significantly change carotenoids and sugars contents. However, there was a reduction of ascorbic acid concentration with an increase of the dose, which may have been caused by irradiation or by intrinsic and extrinsic factors that alter ascorbic acid stability in food, converting ascorbic to dehydroascorbic acid, while keeping the C vitamin active form. (author)

  9. Effect of temperature variations during cooking and storage on ascorbic acid contents of vegetables: a comparative study

    International Nuclear Information System (INIS)

    Zaman, W.U.; Akram, M.; Rehman, R.

    2013-01-01

    Summary: Vegetables are generally boiled for cooking or stored in refrigerators. This results in loss of their nutritional values. Ascorbic acid is one of the important nutrients for human health. In this study, Ascorbic acid (vitamin-C) content of various vegetables of Pakistan was determined, and effect of boiling and freezing were compared with natural Ascorbic acid contents by HPLC. The maximum concentration of Ascorbic acid was found in green chilli: i.e. 105 mg /100 g in fresh state; while in boiled and frozen state its concentration is comparatively less: i.e. 85 and 92 mg/100 g respectively. The other vegetables like: cabbage, to mato, turnip, potato, spinach, onion, garlic, green pea, green beans and cauliflower contained greater amount of Ascorbic acid in their fresh state i.e. 30, 20, 25.3, 20, 30, 24.3, 31, 28.5, 30, 42 mg/100 g as compared to frozen (23.4, 13, 23.6, 15, 23.4, 14.1,25, 26.5, 27.0, and 39 mg/100g respectively) and boiled state (11.6, 9.3, 22.5, 10.0, 20.3, 13.1, 23, 25.2 and 35 mg /100g respectively). The minimum amount of Ascorbic acid was found in boiled state of carrot and lettuce: i.e. 4.0 mg/100 g. These results showed that freezing or boiling of vegetables causes significant lo ss of available Ascorbic acid contents, especially boiling. (author)

  10. Optimization of condition for conjugation of enrofloxacin to enzymes in chemiluminescence enzyme immunoassay

    Science.gov (United States)

    Yu, Songcheng; Yu, Fei; Zhang, Hongquan; Qu, Lingbo; Wu, Yongjun

    2014-06-01

    In this study, in order to find out a proper method for conjugation of enrofloxacin to label enzymes, two methods were compared and carbodiimide condensation was proved to be better. The results showed that the binding ratio of enrofloxacin and alkaline phosphatase (ALP) was 8:1 and that of enrofloxacin and horseradish peroxidase (HRP) was 5:1. This indicated that conjugate synthesized by carbodiimide condensation was fit for chemiluminescence enzyme immunoassay (CLEIA). Furthermore, data revealed that dialysis time was an important parameter for conjugation and 6 days was best. Buffer to dilute conjugate had little effect on CLEIA. The storage condition for conjugates was also studied and it was shown that the conjugate was stable at 4 °C with no additive up to 30 days. These data were valuable for establishing CLEIA to quantify enrofloxacin.

  11. [Effect of UV-radiation on the level of ascorbic acid, SH-groups, and activity of glutathione reductase in the eye lens].

    Science.gov (United States)

    Byshneva, L N; Senchuk, V V

    2002-01-01

    The effect of UV radiation in vitro on the level of ascorbate, SH-groups and glutathione reductase activity in the soluble fraction of bovine eye lens was studied. UV-Irradiation increased NADPH-oxidoreductase activity, the level of ascorbate oxidation and decreased the content of SH-groups and activity of glutathione reductase. Significant activation of the NADPH-oxidoreductase activity in the presence of ascorbate and Cu2+ was observed after UV-irradiation. It is suggested that ascorbate may play an important role in the UV-induced lens pathology.

  12. Zinc affects differently growth, photosynthesis, antioxidant enzyme activities and phytochelatin synthase expression of four marine diatoms.

    Science.gov (United States)

    Nguyen-Deroche, Thi Le Nhung; Caruso, Aurore; Le, Thi Trung; Bui, Trang Viet; Schoefs, Benoît; Tremblin, Gérard; Morant-Manceau, Annick

    2012-01-01

    Zinc-supplementation (20 μM) effects on growth, photosynthesis, antioxidant enzyme activities (superoxide dismutase, ascorbate peroxidase, catalase), and the expression of phytochelatin synthase gene were investigated in four marine diatoms (Amphora acutiuscula, Nitzschia palea, Amphora coffeaeformis and Entomoneis paludosa). Zn-supplementation reduced the maximum cell density. A linear relationship was found between the evolution of gross photosynthesis and total chlorophyll content. The Zn treatment decreased the electron transport rate except in A. coffeaeformis and in E. paludosa at high irradiance. A linear relationship was found between the efficiency of light to evolve oxygen and the size of the light-harvesting antenna. The external carbonic anhydrase activity was stimulated in Zn-supplemented E. paludosa but was not correlated with an increase of photosynthesis. The total activity of the antioxidant enzymes did not display any clear increase except in ascorbate peroxidase activity in N. palea. The phytochelatin synthase gene was identified in the four diatoms, but its expression was only revealed in N. palea, without a clear difference between control and Zn-supplemented cells. Among the four species, A. paludosa was the most sensitive and A. coffeaeformis, the most tolerant. A. acutiuscula seemed to be under metal starvation, whereas, to survive, only N. palea developed several stress responses.

  13. Zinc Affects Differently Growth, Photosynthesis, Antioxidant Enzyme Activities and Phytochelatin Synthase Expression of Four Marine Diatoms

    Directory of Open Access Journals (Sweden)

    Thi Le Nhung Nguyen-Deroche

    2012-01-01

    Full Text Available Zinc-supplementation (20 μM effects on growth, photosynthesis, antioxidant enzyme activities (superoxide dismutase, ascorbate peroxidase, catalase, and the expression of phytochelatin synthase gene were investigated in four marine diatoms (Amphora acutiuscula, Nitzschia palea, Amphora coffeaeformis and Entomoneis paludosa. Zn-supplementation reduced the maximum cell density. A linear relationship was found between the evolution of gross photosynthesis and total chlorophyll content. The Zn treatment decreased the electron transport rate except in A. coffeaeformis and in E. paludosa at high irradiance. A linear relationship was found between the efficiency of light to evolve oxygen and the size of the light-harvesting antenna. The external carbonic anhydrase activity was stimulated in Zn-supplemented E. paludosa but was not correlated with an increase of photosynthesis. The total activity of the antioxidant enzymes did not display any clear increase except in ascorbate peroxidase activity in N. palea. The phytochelatin synthase gene was identified in the four diatoms, but its expression was only revealed in N. palea, without a clear difference between control and Zn-supplemented cells. Among the four species, A. paludosa was the most sensitive and A. coffeaeformis, the most tolerant. A. acutiuscula seemed to be under metal starvation, whereas, to survive, only N. palea developed several stress responses.

  14. Against Drought Stress Effect of Antioxidant Enzymes of Boron

    Directory of Open Access Journals (Sweden)

    Mahmut Doğan

    2013-04-01

    Full Text Available In this study, soybean seeds (Glycine max. L., cv., “A3935 were grown under controlled conditions (25±2 C composed of different boron compounds. In the experiment, 5 groups were determined respectively as potassium tetraborate tetrahydrate (1 mg/1, ammonium tetraborate tetrahydrate (1 mg/1, sodium boron hydride (1 mg/1, lithium tetraborate tetrahydrate (100 mg/1, and sodium tetraborate decahydrate (100 mg/1. The doses used in this study were determined according to the results of a preliminary study. Soybean seeds were exposed to different amounts of drought stress based on time (control, 3, 6, 9, 12, 15, and 18 days. Activities of antioxidant enzymes superoxide dismutase (SOD: EC 1.15.1.1, glutathione reductase (GR: EC 1.6.4.2, ascorbate peroxidase (APX: EC 1.11.1.11 and catalase (CAT: EC 1.11.1.6 measured. According to the results stress+potassium tetraborate tetrahydrate environment has increased the amount of CAT, decreased the amount GR, APX and SOD. Potassium tetraborate 0.1 mg / l dose administration is the most appropriate critical value, and the most important indicator of drought CAT enzyme found to give the best results.

  15. Hfq stimulates the activity of the CCA-adding enzyme

    Directory of Open Access Journals (Sweden)

    Betat Heike

    2007-10-01

    Full Text Available Abstract Background The bacterial Sm-like protein Hfq is known as an important regulator involved in many reactions of RNA metabolism. A prominent function of Hfq is the stimulation of RNA polyadenylation catalyzed by E. coli poly(A polymerase I (PAP. As a member of the nucleotidyltransferase superfamily, this enzyme shares a high sequence similarity with an other representative of this family, the tRNA nucleotidyltransferase that synthesizes the 3'-terminal sequence C-C-A to all tRNAs (CCA-adding enzyme. Therefore, it was assumed that Hfq might not only influence the poly(A polymerase in its specific activity, but also other, similar enzymes like the CCA-adding enzyme. Results Based on the close evolutionary relation of these two nucleotidyltransferases, it was tested whether Hfq is a specific modulator acting exclusively on PAP or whether it also influences the activity of the CCA-adding enzyme. The obtained data indicate that the reaction catalyzed by this enzyme is substantially accelerated in the presence of Hfq. Furthermore, Hfq binds specifically to tRNA transcripts, which seems to be the prerequisite for the observed effect on CCA-addition. Conclusion The increase of the CCA-addition in the presence of Hfq suggests that this protein acts as a stimulating factor not only for PAP, but also for the CCA-adding enzyme. In both cases, Hfq interacts with RNA substrates, while a direct binding to the corresponding enzymes was not demonstrated up to now (although experimental data indicate a possible interaction of PAP and Hfq. So far, the basic principle of these stimulatory effects is not clear yet. In case of the CCA-adding enzyme, however, the presented data indicate that the complex between Hfq and tRNA substrate might enhance the product release from the enzyme.

  16. Enzyme Inhibitory and Molecular Docking Studies on Some Organic Molecules of Natural Occurrence

    International Nuclear Information System (INIS)

    Abbasi, M. A.; Hussain, G.; Rehman, A. U.; Shahwar, D.; Mohyuddin, A.; Ashraf, M.; Rahman, J.; Lodhi, M. A.; Khan, F. A.

    2016-01-01

    In the present study, in vitro enzyme inhibitory studies on cinchonidine (1), cinchonine (2), quinine (3), noscapine (narcotine, 4) and santonine (5) were carried out. The various enzymes included in the study were lipoxygenase, xanthine oxidase, acetyl cholinesterase, butyryl cholinesterase and protease. The results revealed that 2, 3, and 4 were moderate active against lipoxygenase and xanthine oxidase enzymes. The molecule 3 possessed weak activity against butyryl cholinesterase enzyme while remaining molecules were inactive against this enzyme. However, all these compounds were inactive against acetyl cholinestrase and protease enzymes. The synthesized compounds were computationally docked into the active site of lipoxygenase enzyme. The compounds 3 and 4 showed decent interactions, hence strengthening the observed results. (author)

  17. Syntheses of copper complexes of nicotinohydroxamic and ...

    African Journals Online (AJOL)

    Nicotinohydroxamic acid (NHA) and isonicotinohydroxamic acid (INHA) were synthesized, characterized by electronic and spectral studies,magnetic measurements and their pKa determined spectrophotometrically as 8.68 ± 0.02 in aqueous medium of 0.1mol dm-3 I=ionic strength. The composition of the complexes was ...

  18. SYNTHESES AND PROPERTIES OF SOME ORGANOSILANE POLYMERS

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xinghua; Robert West

    1984-01-01

    Some organosilane polymers with high molecular weights have been synthesized by cocondensation of organosilicon dihalide monomers with sodium metal in toluene. These polymers are both soluble in common solvents and meltable at lower temperatures, and can be molded, cast into films or drawn into fibers. Exposure of the solid polymers to ultraviolet light leads to degradation or crosslinking.

  19. Biological activities of synthesized silver nanoparticles

    Indian Academy of Sciences (India)

    The C. halicacabum leaf extract synthesized AgNPs efficiency were tested against different bacterial pathogens MTCC-426 Proteus vulgaris, MTCC-2453 Pseudomonas aeruginosa, MTCC-96 Staphylococcus aureus, MTCC-441 Bacillus subtilis andMTCC-735 Salmonella paratyphi, and fungal pathogens Alternaria solani ...

  20. Synthesizing chaotic maps with prescribed invariant densities

    International Nuclear Information System (INIS)

    Rogers, Alan; Shorten, Robert; Heffernan, Daniel M.

    2004-01-01

    The Inverse Frobenius-Perron Problem (IFPP) concerns the creation of discrete chaotic mappings with arbitrary invariant densities. In this Letter, we present a new and elegant solution to the IFPP, based on positive matrix theory. Our method allows chaotic maps with arbitrary piecewise-constant invariant densities, and with arbitrary mixing properties, to be synthesized