RESUMEN
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 quantitatively evaluated and their structures assigned. BHA and t-BHQ yielded reaction products with anilines only in the presence of an oxidant such as iodate (KIO3). We used the Salmonella/microsome mutagenicity assay to test the new compounds for mutagenic activity. The reaction products gave no evidence of mutagenicity in the S. typhimurium strains TA98 and TA100, with or without metabolic activation. In some instances the substituted quinone products are less toxic than t-BuQ alone.
Asunto(s)
Antioxidantes/metabolismo , Antioxidantes/toxicidad , Hidroxianisol Butilado/metabolismo , Hidroxianisol Butilado/toxicidad , Compuestos de Anilina/química , Antioxidantes/química , Benzoquinonas/química , Hidroxianisol Butilado/química , Cromatografía en Capa Delgada , Hidroquinonas/química , Microsomas , Pruebas de Mutagenicidad , Salmonella typhimuriumRESUMEN
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), tert-butyl-substituted para-quinone (t-BuQ) and 3-tert-butyl-5-methoxy-1,2-benzoquinone (t-Bu-o-Q) are dominant. The last compound has not been previously reported in this system. Spot testing indicated at least one further compound of nitroso character and traces of tert-butylhydroquinone (t-BuHQ), which reacts with nitrite to yield t-BuQ. No evidence was found for the formation of the BHA dimer under our conditions. The substances gave no evidence of mutagenicity in the Salmonella typhimurium strains TA 98 and TA 100, either in the standard plate incorporation assay or in the procedure with preincubation with or without S9 mix. In some instances the substances were unstable in the test procedure.
Asunto(s)
Benzoquinonas , Hidroxianisol Butilado , Mutágenos/aislamiento & purificación , Nitritos , Hidroxianisol Butilado/aislamiento & purificación , Hidroxianisol Butilado/farmacología , Fenómenos Químicos , Química , Cromatografía en Capa Delgada , Hidroquinonas/aislamiento & purificación , Hidroquinonas/farmacología , Pruebas de Mutagenicidad , Quinonas/aislamiento & purificación , Quinonas/farmacologíaRESUMEN
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 from reduced reactant diffusion in solutions of increased viscosity rather than the preferential chelation previously suggested to explain inhibition in the copper (II) catalyzed oxidation. The ascorbic acid free radical shows negligible tendency to react with glucose, sorbitol or maltose. The decrease in its decay rate observed on addition of carbohydrate is probably caused by the increase in solvent viscosity.
Asunto(s)
Ácido Ascórbico , Carbohidratos/farmacología , Espectroscopía de Resonancia por Spin del Electrón , Ferricianuros/farmacología , Radicales Libres , Glucosa/farmacología , Cinética , Maltosa/farmacología , Oxidación-Reducción , Soluciones , Sorbitol/farmacología , AguaRESUMEN
42 to 75 pCi cesium-137 and 702 to 903 pCi strontium-90 per kg were found in samples of tobacco of German origin and from commercial cigarette. The presence of these radionuclides in tobacco is attributed to the fallout from nuclear explosions. Taking into consideration mean transfer rates of the radionuclides in the main stream smoke condensate and average consumption of cigarettes, whole body radiation doses for inhalation have been calculated to be in the range 10(-3) to 10(-4) mrem/year and per person. This means, they are in the same order of magnitude as radiation doses by inhalation of ambient air. They are smaller by a factor of 10(-4) than the radiation exposure due to ingestion of these radionuclides from the total diet.
Asunto(s)
Radioisótopos de Cesio/análisis , Nicotiana/análisis , Plantas Tóxicas , Radioisótopos de Estroncio/análisis , Alemania Occidental , Humanos , Guerra Nuclear , Dosis de Radiación , Ceniza Radiactiva/efectos adversos , FumarRESUMEN
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 absence of inhibitors. Evidence suggests that radical formation arises via secondary reactions involving products.
Asunto(s)
Ácido Ascórbico , Quelantes/farmacología , Ácido Edético/farmacología , Radicales Libres , Polifosfatos/farmacología , SolucionesRESUMEN
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 mutagenicity of 2,3-diketogulonic acid, one of the main oxidation products, reflects its ability to form hydrogen peroxide.
Asunto(s)
Ácido Ascórbico , Mutágenos , Mutación , Ácido Ascórbico/farmacología , Radicales Libres , Cinética , Pruebas de Mutagenicidad , Oxidación-Reducción , Salmonella typhimurium/efectos de los fármacosRESUMEN
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.
Asunto(s)
Ácido Ascórbico , Nitritos , Nitrosaminas , Anaerobiosis , Ácido Deshidroascórbico , Espectroscopía de Resonancia por Spin del Electrón , Radicales Libres , Oxidación-ReducciónRESUMEN
Apples of the two varieties, Boskoop and Brettacher, were exposed to 35S labeled sulphur dioxide. After storage at several conditions the distribution of 35S-activity among the three fractions, sulphite, sulphate and sulphonate was examined. The major portion of the radioactivity was found in the sulphate fraction. The activity decreased remarkably from the peel towards the core. Appreciable differences in distribution patterns were found between the two apples varieties.
Asunto(s)
Frutas/análisis , Dióxido de Azufre/metabolismo , Conservación de Alimentos , Plantas Comestibles/metabolismo , Especificidad de la Especie , Sulfatos/metabolismo , Sulfitos/metabolismo , Ácidos Sulfónicos/metabolismoRESUMEN
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 overall second order kinetics, being however first order in the presence of hydrogen peroxide. The protective effect of sulphur dioxide is proposed to have nutritional implications.