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Reactividad del anión radical superóxido con nitrones cíclicos: papel de los enlaces H intramoleculares y efectos

Frederick A Villamena¹, Shijing Xia, John K Merle

¹Department of Pharmacology, Center for Biomedical EPR Spectroscopy and Imaging, The Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA. frederick.villamena@osumc.edu

Journal of the American Chemical Society

|June 15, 2007

Resumen

Los investigadores desarrollaron nuevas trampas de espín para detectar radicales libres biológicos utilizando espectroscopia de resonancia paramagnética electrónica (EPR). Métodos computacionales y experimentales identificaron grupos funcionales ideales para la detección mejorada de aniones radicales de superóxido in vivo.

Área de la Ciencia:

Química Química es la química.
La bioquímica es la bioquímica.
La espectroscopia es una técnica de espectroscopia.

Sus antecedentes:

Las actuales trampas de espín de nitrón cíclico tienen limitaciones para la detección de radicales libres biológicos a través de la espectroscopia de resonancia paramagnética de electrones (EPR).
Diseñar trampas de espín efectivas es un desafío debido a la falta de enfoques sistemáticos.
El anión radical superóxido (O2*-) es un radical libre biológico clave implicado en varios procesos fisiológicos y patológicos.

Objetivo del estudio:

Investigar computacional y experimentalmente la reactividad de trampas de espín funcionalizadas con el anión radical superóxido (O2*-).
Para racionalizar el efecto de la sustitución de grupos funcionales en el rendimiento de la trampa de giro.
Identificar mejores estrategias de captura de espín para mejorar la detección in vivo de los radicales superóxido.

Principales métodos:

Los cálculos de la teoría funcional de densidad (DFT, por sus siglas en inglés) se realizaron en los niveles PCM/B3LYP/6-31+G(d,p)//B3LYP/6-31G(d) y PCM/mPW1K/6-31+G(d,p).
La cinética de flujo detenido y la espectroscopia EPR se utilizaron para determinar experimentalmente las constantes de velocidad.
Los modelos computacionales fueron validados contra datos experimentales.

Principales resultados:

Las energías libres calculadas y las constantes de velocidad para las reacciones de nitrón-O2*- se correlacionaron bien con los hallazgos experimentales.
La sustitución del grupo funcional en la posición C-5 de los N-óxidos de pirrolina tiene un impacto significativo en la reactividad de la trampa de giro.
Se aclaró la naturaleza nucleofílica de la adición de O2* y el papel del enlace de hidrógeno intramolecular.

Conclusiones:

Las amidas o ésteres sustituidos por N-monoalquilos son grupos funcionales ideales para mejorar las propiedades de captura de espín.
Este estudio proporciona una estrategia de diseño racional para nuevas trampas de espín.
Los hallazgos allanan el camino para una mejor detección in vivo de los radicales superóxido en su lugar de formación.

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