BUSCADOR RECOLECTA

[EN] Nitroso-compounds are potentially mutagenic and carcinogenic compounds due to their ability to alkylate DNA bases. One of the most common sources of human exposure to nitroso-compounds is their formation in the acidic environment of the stomach by the reaction between electron-rich molecules present in the lumen and sodium nitrite ingested in the diet. To date, the formation of nitroso-compounds by the reaction of nitrite with food components has been investigated in depth, but little attention has been paid to substances secreted in the stomach, such as dopamine or serotonin, whose reaction products with nitrite have proven mutagenic properties. In this article we present a kinetic study with UV-visible spectroscopy of the nitrosation reactions of both molecules, as well as of L-tyrosine, the amino-acid precursor of dopamine. As a result, we have determined their reaction mechanisms, which show that in all of them the favoured reaction product is a stable nitroso-compound and that the molecule whose product is the most mutagenic, serotonin, undergoes two consecutive nitrosation reactions. These findings suggest that more research is needed to understand how this reaction alters the function of these neurotransmitters as well as the potential toxic effects they may have once nitrosated., a) Ministerio de Economía y Competitividad and the European Regional Development Fund. b) Universidad de Salamanca. M.G.J. had got a PhD. grant of the Ministerio de Economía y Competitividad J.A.V. had got a PhD. grant of the Junta de Castilla y León for a PhD. grant., Carpeta 1. Tirosine: 1. Extinction coefficient , 2. Extinction coefficient nitrosotirosine, 3. Reaction orders, 4. Influence Ionic ,Strength, 5. Influence Temperature, 6. Influence pH, 7. KIE. Carpeta 2. Dopamine: 1. Extinction coefficient, 2. Selfoxidation dopamine, 3. Extinction coefficient nitrosodopamine, 4. Catalysis by chloride ions, 5. Reaction orders, 6. Influence Ionic Strength, 7. Influence Temperature, 8. KIE. Carpeta 3. Serotonin: 1. Extinction coefficient, 2. Extinction coefficient nitrosated serotonin, 3. Influence Ionic Strength, 4. Reaction orders, 5. Influence pH, 6. Influence Temperature, 7. KIE