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Transferencia extremadamente rápida de átomos de hidrógeno entre los nitróxidos y los radicales HOO y su implicación
Andrea Baschieri1, Luca Valgimigli1, Simone Gabbanini2
1Department of Chemistry "G. Ciamician" , University of Bologna , Via S. Giacomo 11 , 40126 Bologna , Italy.
Journal of the American Chemical Society
|July 20, 2018
Resumen
Un nuevo sistema antioxidante que utiliza TEMPO (radical 2,2,6,6-tetrametilpiperidina-1-oxilo) detiene rápidamente el daño oxidativo mediante la conversión eficiente de los radicales. Este sistema TEMPO ofrece una protección superior en comparación con los antioxidantes naturales como el alfa-tocoferol.
Área de la Ciencia:
- Química
- La bioquímica
- Investigación de los antioxidantes
Sus antecedentes:
- El estrés oxidativo daña las moléculas biológicas a través de reacciones en cadena radicales.
- Los antioxidantes liposolubles como el alfa-tocoferol son cruciales para la protección, pero pueden ser menos efectivos en ciertos entornos.
- Comprender los nuevos mecanismos antioxidantes es clave para desarrollar mejores estrategias de protección.
Objetivo del estudio:
- Introducir y caracterizar un nuevo sistema de coantioxidantes basado en TEMPO.
- Investigar la eficacia de TEMPO en el apagado de las especies reactivas de oxígeno en sistemas modelo biológicamente relevantes.
- Comparar la eficacia antioxidante del sistema TEMPO con los antioxidantes conocidos.
Principales métodos:
- Se utilizaron sistemas modelo biológicamente relevantes para estudiar la actividad antioxidante.
- Las constantes de velocidad medidas para las reacciones clave que implican TEMPO, TEMPOH y radicales hidroperoxilo (HOO·).
- Se compararon los datos cinéticos con los del alfa-tocoferol.
Principales resultados:
- El sistema TEMPO convierte rápidamente los radicales alquilperóxilo portadores de cadenas en HOO·.
- TEMPO apaga eficazmente el HOO, bloqueando las reacciones en cadena oxidativas.
- Las constantes de velocidad para las reacciones mediadas por TEMPO (1.1 × 10^9 M^-1 s^-1 y 5.0 × 10^7 M^-1 s^-1) exceden significativamente las del alfa-tocoferol (1.6 × 10^6 M^-1 s^-1).
Conclusiones:
- La pareja TEMPO/TEMPOH establece un ciclo catalítico reductivo eficiente, protegiendo las moléculas orgánicas en entornos lipofílicos.
- Este sistema proporciona una nueva comprensión de la eficacia antioxidante de TEMPO en sistemas no acuosos.
- TEMPO muestra potencial como agente quimioprotector contra el daño de los radicales.
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