Products of gamma-tocopherol reaction with NO2 and their formation in rat insulinoma (RINm5F) cells
| Autor: | Lawrence J. Mordan, Kavitha K. Narala, Robert V. Cooney, Patricia J. Harwood, Adrian A. Franke, Per Olof Berggren, Anna Karin Sundström |
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| Rok vydání: | 1995 |
| Předmět: |
Magnetic Resonance Spectroscopy
Time Factors Kinetics Photochemistry Nitric Oxide Biochemistry Medicinal chemistry Mass Spectrometry Cell Line chemistry.chemical_compound Physiology (medical) Nitration Tumor Cells Cultured Animals Vitamin E Neoplastic transformation Reactivity (chemistry) Tocopherol Nitrite Biotransformation Chromatography High Pressure Liquid Molecular Structure food and beverages Tautomer Rats Pancreatic Neoplasms chemistry Yield (chemistry) lipids (amino acids peptides and proteins) Insulinoma Oxidation-Reduction |
| Zdroj: | Free radical biologymedicine. 19(3) |
| ISSN: | 0891-5849 |
| Popis: | gamma-Tocopherol, commonly found in seed oils, is the major tocopherol in the U.S. diet, is superior to alpha-tocopherol in preventing neoplastic transformation, and demonstrates unique reactivity toward NO2. This article describes the products of reaction between gamma-tocopherol and low concentrations of gaseous nitrogen dioxide (NO2), as well as their endogenous formation in NO-producing RINm5F cells. gamma-Tocopherol in hexane reacts with NO2 to yield two products identified as 2,7,8-trimethyl-2(4,8,12-trimethyltridecyl)-5,6-chromaquinone++ +, "tocored," and 2,7,8 trimethyl-2(4,8,12-trimethyltridecyl) 5-nitro, 6-chromanol, "tocoyellow." Physical data for these two compounds and reaction characteristics are described. The formation of tocored is consistent with a proposed mechanism of gamma-tocopherol-mediated reduction of NO2 to NO involving initial reaction by NO2 at the C-5 position to form an intermediate nitrite ester tocopheryl radical, which then reacts internally to release NO and form 5,6 epoxy gamma-tocopherol. Tautomerization and further oxidation of the latter intermediate by NO2 yields tocored as the main product observed. The reaction of gamma-tocopherol with NO2 to form NO occurs independently of light, whereas alpha-tocopherol requires light to generate NO from NO2. gamma-Tocopherol and aminoguanidine, an NO synthase inhibitor, were superior to alpha-tocopherol in preventing RINm5F cell toxicity induced by Interleukin-1 beta (IL-1 beta). Both tocored and tocoyellow were observed to form in RINm5F cells loaded with gamma-tocopherol and producing NO constitutively, although a consistent increase in these products as a result of induced NO synthesis was not observed. |
| Databáze: | OpenAIRE |
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