Mate (MT) is a popular South American beverage that has been used as a traditional medicine for centuries, spurring recent interest in its nutraceutical properties. MT is prepared as an infusion of leaves from the Yerba Mate (llex paraguriensis) tree. MT has been reported to have antioxidant properties in vitro and in vivo, but these have not been fully characterized in terms of effects against specific radicals. Accordingly, we examined the antioxidant effects of an MT infusion against hydroxyl and superoxide radicals in both chemical and cell culture assays. MT infusions were prepared at 3.10 g/L in boiling water and diluted to experimental dilutions from this stock. Electron spin resonance (ESR) experiments indicated that MT scavenged hydroxyl radicals (produced via the Fenton reaction) and superoxide radicals (produced via the xanthine/xanthine oxidase enzymatic reaction) at all concentrations tested (P < 0.05). Further controls indicated that superoxide radical scavenging was not due to xanthine oxidase inhibition. MT scavenged hydroxyl radicals and decreased cellular oxygen consumption in a dose-dependent manner in Cr(VI)-stimulated RAW 264.7 cells, based on ESR and oxygraph measurements (P < 0.05). Similarly, MT also inhibited hydroxyl-radical-induced lipid peroxidation and DNA damage in a dose-dependent manner in RAW 264.7 cells, based on malondialdehyde and Comet assay data (P < 0.05). This study indicates that MT possesses potent antioxidant effects against hydroxyl and superoxide radicals in both chemical and cell culture systems, as well as DNA-protective properties. These data further clarify the reported antioxidant effects of Yerba Mate infusions.

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En el presente trabajo son analizados 31 libros de educación secundaria correspondientes al Ciclo Básico Uruguay, en relación al abordaje de la enseñanza del tema agua en estos textos. Se estudian los textos de las siguientes asignaturas: Ciencia Físicas (química y física), Biología, geografía, Química y Física. El estudio se realiza por metodología cuantitativa de acuerdo a D´Ancona (1998), contando las veces que aparece la palabra agua, las disciplinas que se relacionan en el texto y las actividades propuestas siempre referidas al tema. Los textos analizados son los recomendados oficialmente y que figuran en los programas actuales de enseñanza. De los resultados obtenidos se verifica la heterogeneidad de los textos, que no permiten la elaboración de subgrupos para su análisis, sea por disciplinas o nivel educativo. Se evidencia un mayor porcentaje de la motivación extrínseca en las tareas y actividades de los libros y al estudiar la relación entre disciplinas las uniones entre física, química, biología y geografía son recurrentes.