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1Author    Wolfgang Lohmann, Rainer LangeRequires cookie*
 Title    On the Possible Involvement of Ascorbic Acid and Copper Proteins in Leukemia. III. ESR Investigations on the Interaction between Ascorbic Acid and Some Transition Metal Ions  
 Abstract    The interaction between lyophilized samples of ascorbic acid and Cu2+, Fe3+ or M n2+ has been investigated by means of ESR spectroscopy. All of the three transition metal ions form complexes with vitamin C, but only in the case of C u2+ and Fe3+ the interaction results in a reduction of the metal ions. C u2+ and ascorbic acid seem to form 2 : 1 complexes with an equilibrium constant of about K = 1 x 107 mol-1. None of these metal ion complexes exhibits, however, the ESR spectrum obtained with leukemic blood. 
  Reference    Z. Naturforsch. 34c, 546—549 (1979); received March 21/May 4 1979 
  Published    1979 
  Keywords    Leukemia, ESR, Ascorbic Acid, Transition Metal Ions 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-0546.pdf 
 Identifier    ZNC-1979-34c-0546 
 Volume    34 
2Author    Wolfgang Lohmann, Jörg Schreiber, Walter Greulich, LeukemiaRequires cookie*
 Title    On the Possible Involvement of Ascorbic Acid and Copper Proteins in  
 Abstract    The interaction between lyophilized samples of ascorbic acid and some copper proteins (ceru-loplasmin, cytochrome-c-oxidase, ascorbate-oxidase) has been investigated by means of ESR spec­ troscopy. The spectra obtained are identical to the one obtained with leukemic blood. The conse­ quences of this for the molecular events occuring in cancer are discussed. The model proposed can explain the experimental findings reported thus far (such as change in spin concentration with the development of cancer, the presence of a high concentration of antioxidants etc.) as well as recon-sile the two existing and seemingly contradictory hypothesis. Possible implications for lipid per­ oxidation and for the respiratory process are discussed. 
  Reference    Z. Naturforsch. 34c, 550—554 (1979); received March 21/May 4 1979 
  Published    1979 
  Keywords    Leukemia, ESR, Ascorbic Acid, Copper Proteins, Lipid Peroxidation 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-0550.pdf 
 Identifier    ZNC-1979-34c-0550 
 Volume    34 
3Author    Wolfgang Lohmann, KlausG. Bensch, Jörg Schreiber, Elisabeth Müller, Konrad Schwemmle, Herbert Feustel, Rolf-Dieter FillerRequires cookie*
 Title    Paramagnetic Changes in Pulmonary Tumors  
 Abstract    Electron spin resonance studies on healthy and tum erous hum an lung samples have been con­ ducted in order to determ ine possible differences in free radical concentration and shape o f the spectra between the different sections o f the lung. It could be shown that in healthy lung tissue the signal caused by the sem idehydroascorbate (SDA) radical is not prom inent because o f the prevailing high partial oxygen pressure. On form ation o f a tumor, the spin concentration increases, possibly due to the higher metabolic rate; here, the SDA peak is also more pronounced which indicates alterations in the interaction between cell constituents and ascorbic acid. W ithin the tum or, the spin concentration is considerably reduced which is probably caused by a still higher concentration o f ascorbic acid. A ddition o f ascorbic acid to the different lung specimens enhanced the just described effect while oxidizing substances, such as H 2Oa, reversed it. 
  Reference    Z. Naturforsch. 36c, 5—8 (1981); received Septem ber 9/O ctober 20 1980 
  Published    1981 
  Keywords    ESR, Pulmonary Tumors, Ascorbic Acid, Spin Concentration 
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 TEI-XML for    default:Reihe_C/36/ZNC-1981-36c-0005.pdf 
 Identifier    ZNC-1981-36c-0005 
 Volume    36 
4Author    Wolfgang LohmRequires cookie*
 Title    Ascorbate Oxidase and Its Possible Involvement in Cancer  
 Abstract    The electron spin resonance (ESR) spectrum of erythrocytes of a healthy male volunteer exhibited 2 min after intravenous administration of 1 g of ascorbic acid a considerable increase in spin concentration and a new signal at about g = 2.005 which we previously had found to correlate to the semidehydroascorbate (SDA) radical and which is not identical with the O j radical. Moreover, the vitamin C concentration in erythrocytes and plasma was considerably higher than in comparable samples of other volunteers treated identically. In the latter cases, the ESR spectrum of the erythrocytes was not modified at all. These findings suggest that there must be a substance which reacts with ascorbic acid specifically. It can be assumed that the enzyme ascorbate oxidase plays this decisive role in the ascorbic acid metabolism. For this reason, different amounts of ascorbate oxidase have been added to healthy erythrocytes treated in vitro with ascorbic acid and to tissue samples of lung cancer. As expected, the vitamin C effect as expressed by the appearance of the SDA signal and the increase in spin concentration could be reversed. It is suggested, therefore, that in special types of cancer, such as acute lymphatic leukemia and lung cancer, the concentration of ascorbate oxidase or of an enzyme acting like it is, primarily, diminished, while in other types it might be enlarged. 
  Reference    Z. Naturforsch. 36c, 804—808 (1981); received February 9/March 211981 
  Published    1981 
  Keywords    Ascorbic Acid, ESR, Copper Proteins, Leukemia, Lung Cancer 
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 TEI-XML for    default:Reihe_C/36/ZNC-1981-36c-0804.pdf 
 Identifier    ZNC-1981-36c-0804 
 Volume    36 
5Author    Carl Fedtke, RobertH. Strang, Bayer Ag, Geschäftsbereich Pflanzenschutz, Biologische Anwendungstechnik, ForschungRequires cookie*
 Title    Synergistic Activity of the Herbicide Safener Dichlormid with Herbicides Affecting Photosynthesis  
 Abstract    Dichlormid, a safener for thiolcarbamate herbicides, was tank-mixed with several herbicidal inhibitors of photosystem II, or with the herbicide acifluorfen, and applied postemergence to Ipomoea hederacea plants. Dichlormid had no visible effects on the plants when applied alone, but interacted synergistically with the herbicides in the combination treatments. Dichlormid strongly decreased the ascorbic acid levels in the Ipom oea hederacea cotyledons. Ascorbate is known to protect plant tissue from photooxidative damage. The herbicides which interacted synergistically with dichlormid are believed to generate their phytotoxic action via the produc­ tion of excess singlet oxygen. It is suggested that the decreased ascorbate levels in the Ipomoea hederacea cotyledons after dichlormid treatment result in an impaired singlet oxygen scaveng­ ing system and consequently lead to increased plant damage in the presence of singlet oxygen generating herbicides. 
  Reference    Z. Naturforsch. 45c, 565—567 (1990); received October 13 1989 
  Published    1990 
  Keywords    Herbicide, Synergism, Safener, Oxygen Toxicity, Ascorbic Acid 
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 TEI-XML for    default:Reihe_C/45/ZNC-1990-45c-0565.pdf 
 Identifier    ZNC-1990-45c-0565 
 Volume    45 
6Author    A. Kira, W. Adano3, MitsuharuA. Zeta3, Shin-Ichi Itotani3, Ai Kanda3, Toshio Iwaki3, Tom Oaki Tairab, YasushiF. Ujiib, Yoshifumi Nishiurac, HaruhikoM. Urasec, Nobuo HonamRequires cookie*
 Title    Change of Ascorbic Acid Level after Grafting of Tomato Seedlings  
 Abstract    Grafting is an easy way to produce a new seedling, which can tolerate against various stresses. During the acclimation after grafting, however, the seedlings still suffer a severe water stress. It is well known that water stress produces active oxygen to oxidize ascorbic acid. The concentration of ascorbic acid in the leaves was analyzed by HPLC equipped with an electrochemical detector. The column used was SP-120-5-O D S-BP (DAISO, JAPAN) and elution was performed with 0.1 m phosphate buffer, pH 3.0. After grafting the seedlings were acclimated under a 6-hr light/dark regimen. The content of ascorbic acid increased gradually during 2 days compared with control. The ascorbate peroxidase showed about constant activity, so the increase of ascorbic acid may be due to its requirement to cure the grafting. 
  Reference    Z. Naturforsch. 54c, 830—8 (1999); receivced December 20 1998/February 3 1999 
  Published    1999 
  Keywords    Ascorbate Peroxidase, Ascorbic Acid, Glutathione, Grafting, Water Stress 
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 TEI-XML for    default:Reihe_C/54/ZNC-1999-54c-0830.pdf 
 Identifier    ZNC-1999-54c-0830 
 Volume    54 
7Author    Wolfgang LohmannRequires cookie*
 Title    On a Possible Mechanism of Action of Interferon  
 Abstract    The effect o f interferon on the ESR spectra o f erythrocytes treated with ascorbic acid has been investigated. This model system has been chosen since it represents identically the spectra obtained in cases with acute lymphatic leukemia. The data obtained show that small interferon concentrations increase, while larger concentrations decrease the effect produced by ascorbic acid resulting, finally, in the original erythrocyte ESR spectrum. Atomic absorption studies reveal the presence of copper which might be part of the active principle. 
  Reference    Z. Naturforsch. 36c, 323—325 (1981); received November 18 1980 
  Published    1981 
  Keywords    Interferon, Cancer, Ascorbic Acid, Spin Concentration, Electron Spin Resonance Spectrum 
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 TEI-XML for    default:Reihe_C/36/ZNC-1981-36c-0323.pdf 
 Identifier    ZNC-1981-36c-0323 
 Volume    36 
8Author    WernerH. Kalus, WilliamG. FilbyRequires cookie*
 Title    Is there an Equilibrium between A scorbic and Dehydroascorbic Acids?  
 Abstract    The previously reported interaction between ascorbate monoanion and dehydroascorbic acid yielding semidehy-droascorbic acid has been shown to be therm odynam ically unfeasible and non-existent. N o evidence for radical for­ mation in the reinvestigation o f the reaction using ESR spectroscopy under careful exclusion o f air could be found. Our results show that the detection o f the free radical in earlier studies resulted from the reaction of ascorbate with traces of oxygen and/o r metals. 
  Reference    Z. Naturforsch. 36c, 1088—1090 (1981); received May 19 1981 
  Published    1981 
  Keywords    Ascorbic Acid, Dehydroascorbic Acid, Redox Potential, Free Radical, ESR 
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 TEI-XML for    default:Reihe_C/36/ZNC-1981-36c-1088_n.pdf 
 Identifier    ZNC-1981-36c-1088_n 
 Volume    36 
9Author    W. Erner, H. K. Alusa, W. Illiam, G. Filby, RuthM. ÜnznerRequires cookie*
 Title    Chemical Aspects of the Mutagenic Activity of the Ascorbic Acid Autoxidation System  
 Abstract    It has been proposed that the mutagenic activity associated with the ascorbic acid autoxidation system may involve hydrogen peroxide and peroxide radicals. We report here that the mutagenic effect may also partially reside in as yet unknown secondary products. The observed mutagenicity of 2,3-diketogulonic acid, one o f the main oxidation products, reflects its ability to form hydrogen peroxide. 
  Reference    Z. Naturforsch. 37c, 40—45 (1982); received September 16 1981 
  Published    1982 
  Keywords    Ascorbic Acid, Autoxidation, Hydrogen Peroxide, Mutagenic Effect, Oxidation Products 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-0040.pdf 
 Identifier    ZNC-1982-37c-0040 
 Volume    37 
10Author    Krzysztof Lichszteld, Zygmunt Machoy, Anna StępińskaRequires cookie*
 Title    Chemiluminescence in the Coupled Oxidation of Lecithin and Ascorbate  
 Abstract    Chem ilum inescence (CL) that appears during oxidation o f lecithin and ascorbate has been studied. A simple system consisting only o f purified lecithin, which has one double bond, and ascorbate as a physiological reductant with a low redox potential, was used. The CL spectrum o f lecithin contain a strong band lying in the near infrared, and three bands at 20 900 cm -1, 17 700 cm -1 and 15 800 cm -1, being characteristic o f singlet m olecular oxygen (1O a). The effect o f * 0 2 quenchers on both autooxidation processes has also been investigated. The obtained results indicate that the main emitter is the *0 2. An addition o f ascorbate to the system lecithin plus buffer causes a decrease o f CL intensity. That is a result o f stronger quenching properties o f ascorbate and not due to efficiency o f the generation o f *0 2 . 
  Reference    Z. Naturforsch. 40c, 223—226 (1985); received Septem ber 13 1984 
  Published    1985 
  Keywords    Lipid Peroxidation, Singlet Oxygen, Chem ilum inescence, Lecithin, Ascorbic Acid 
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 TEI-XML for    default:Reihe_C/40/ZNC-1985-40c-0223.pdf 
 Identifier    ZNC-1985-40c-0223 
 Volume    40 
11Author    Rudolf MatuschRequires cookie*
 Title    Reduktone und Reduktonate, I Das Redoxpaar Dehydroascorbinsäure-Ascorbinsäure und ihre Anionen Reductones and Reductonates, I The Redox Pair Dehydroascorbic Acid-Ascorbic Acid and Anions  
 Abstract    On the basis of NMR spectroscopy (X H and 1 3 C) it can be shown that in water, dimethyl-sulfoxide and p-dioxane only the tautomer 1 of L-ascorbic acid is found in a measurable amount. Upon formation of the mono-anion l a deprotonation occurs on the hydroxyl group attached to C-3; in addition the hydroxyl group on C-2 is deprotonated in case of the di-anion lb . Both anions do not open the lactone ring. After oxidation with iodine in aqueous solution only the dimer of dehydroascorbic acid is detected. This is hydrolized with a half-life of three hours to the monomeric dehydro ascorbic acid dihydrate 7. In dimethylsulfoxide the oxidation rate is decreased, and therefore the formation of the monomeric non-hydratized dehydroascorbic acid 10 can be monitored. This undergoes ringclosure relatively fast to give the half-ketal 13, the reaction of which via 14 leads to the optical active dimeric dehydroascorbic acid 6 . The L-ascorbic acid acetonide 15 is oxidised by iodine to 16 which undergoes racemization via the enol 17 to give 18. This forms an equilibrium with compound 19. 
  Reference    (Z. Naturforsch. 32b, 562—568 [1977]; eingegangen am 17. Dezember 1976) 
  Published    1977 
  Keywords    Ascorbic Acid, Dehydroascorbic Acid, Dimeric Dehydroascorbic Acid, Dehydroascorbic Acid-dihydrate, Dehydroascorbic Acid-acetonide 
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 TEI-XML for    default:Reihe_B/32/ZNB-1977-32b-0562.pdf 
 Identifier    ZNB-1977-32b-0562 
 Volume    32 
12Author    E. Rre, P.A M W IlliamRequires cookie*
 Title    Interaction of the Vanadyl(IV) Cation with L-Ascorbic Acid and Related Systems  
 Abstract    The interaction of V 0 2+ with L-ascorbic acid and dehydroascorbic acid was investigated by electronic spectroscopy in solution at different pH values. In the case of ascorbic acid, two different solid complexes containing one or two m onodeprotonated ascorbate ligands could be isolated and characterized. With dehydroascorbic acid, interaction begins at pH = 4 but at higher pH values the ligand is hydrolysed irreversibly, generating 2,3-diketogulonic acid. A solid complex containing this ligand could be precipitated at pH = 7. Its spectroscopic behavior confirms the interaction of the cation with an enolised form of the acid. 
  Reference    Z. Naturforsch. 53b, 256—262 (1998); received O ctober 24 1997 
  Published    1998 
  Keywords    Vanadyl(IV), Ascorbic Acid, Oxidation Products, Solution Interactions, Solid Complexes 
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 TEI-XML for    default:Reihe_B/53/ZNB-1998-53b-0256.pdf 
 Identifier    ZNB-1998-53b-0256 
 Volume    53