Tunneling in Green Tea:  Understanding the Antioxidant Activity of Catechol-Containing Compounds. A Variational Transition-State Theory Study

Ismael Tejero,† Núria González-García,† Àngels González-Lafont,*†‡ and José M. Lluch†‡
Departament de Qumica and Institut de Biotecnologia i de Biomedicina, Universitat Autnoma de Barcelona, 08193 Bellaterra (Barcelona), Spain
J. Am. Chem. Soc., 2007, 129 (18), pp 5846–5854
DOI: 10.1021/ja063766t
Publication Date (Web): April 12, 2007
Copyright © 2007 American Chemical Society
†

 Departament de Química.

,
*

In papers with more than one author, the asterisk indicates the name of the author to whom inquiries about the paper should be addressed.

,
‡

 Institut de Biotecnologia i de Biomedicina.

, angels@klingon.uab.es

Abstract

Abstract Image

The catechol functionality present in the catechins is responsible for the protective effects exerted by green tea against a wide range of human diseases. High-level electronic structure calculations and canonical variational transition-state theory including multidimensional tunneling corrections have allowed us to understand the key factors of the antioxidant effectiveness of the catechol group. This catechol group forms two hydrogen bonds with the two oxygen atoms of the lipid peroxyl radical, leading to a very compact reactant complex. This fact produces an extremely narrow adiabatic potential-energy profile corresponding to the hydrogen abstraction by the peroxyl radical, which makes it possible for a huge tunneling contribution to take place. So, quantum-mechanical tunneling highly increases the corresponding rate constant value, in such a way that catechins become able to trap the lipid peroxyl radicals in a dominant competition with the very damaging free-radical chain-lipid peroxidation reaction.

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History

  • Published In Issue May 09, 2007
  • Received May 30, 2006

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