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Journals and Conferences
The relative rate constants for the decay of ascorbate free radical in aqueous solutions in the presence of heavy metal ions, hydrogen peroxide and sulphite were measured the ESR-spectroscopy. The oxidation of ascorbic acid showed a strong pH dependence, reaching a maximum rate at pH 9.6. It was shown that the ascorbic acid radical decay generally follows… (More)
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 system may involve hydrogen peroxide and peroxide radicals. We report there that the mutagenic effect may also partially reside in as yet unknown secondary products. The observed… (More)
The reaction mixture and several products arising from the reaction of butylated hydroxyanisole (BHA) and nitrite in anaerobic aqueous acidic solution were separated and tested in the Salmonella mutagenicity test. Among the nine products separable by thin-layer chromatography, 1-hydroxyl-2-tert-butyl-4-methoxy-6-nitrobenzene (BHA-NO2),… (More)
We examined t-butylhydroquinone (t-BHQ) and t-butylquinone (t-BuQ), two of the major microsomal metabolites of the synthetic antioxidant butylated hydroxyanisole (BHA), for their ability to react with the xenobiotic arylamines aniline and N-methylaniline. A number of substances were isolated by thin-layer chromatography. The main products were… (More)
It is shown that the reaction between vitamin K3 and sodium sulphite under physiological conditions leads to the formation of free radical intermediates.
The influence of added carbohydrate on the decay kinetics of the ascorbic acid free radical generated in deaerated aqueous solutions by the action of potassium ferricyanide on ascorbic acid has been studied. Addition of carbohydrate (less than or equal to 0.5M) generally leads to a small decrease in radical decay rate. In our system this probably arises… (More)
The participation of semiquinone free radicals during the reaction of ascorbic acid with acidified sodium nitrite has been demonstrated by ESR spectroscopy unambiguously for the first time. Scavenging of the nitrosating agent, reflected by the observed free radical concentration, unexpectedly occurs with scarcely varying efficiency over the pH range 0.1–4.5.
The rate of free radical formation in aqueous solutions of ascorbic acid in the presence of chelating agents was measured by the ESR-stopped-flow method. Addition of ethylenediamine tetraacetate and trimetaphosphoric acid to the ascorbic acid-oxygen system results in only a minimal change in the rate of ascorbate free radical formation compared to that in… (More)