On the Importance of Water Molecules in the Theoretical Study of Polyphenols Reactivity toward Superoxide Anion

Laure Lespade

doi:10.1155/2014/740205

Abstract

Numerous studies have shown the benefits of a diet rich in fruits and vegetables. These benefits are partly due to the radical scavenging properties of polyphenols contained in fruits and vegetables since polyphenols can fight against an excess of radicals which goes along inflammation in a certain number of diseases. This pathological state, called oxidative stress, results from the aerobic condition of human organism when OH radical, hydrogen peroxide, superoxide anion, or peroxynitrite is produced in excess. If hydrogen peroxide is easily handled by human defense against radicals, the other radicals can cause damage to biological constituents like lipids, cell membranes, and other biomolecules. This paper is devoted to the theoretical study of the interaction of superoxide anion (O2•-) with a very potent radical scavenger, 1,2,4,6,8-pentahydroxynaphthalene. The importance of hydration of superoxide radical for the reactivity is analyzed. Potential energy surfaces (PES) are calculated for different number of water molecules around the radical and it is shown that the transition barrier vanishes when complete hydration with six water molecules is explicitly handled. The nature of the reactivity is determined by using the natural bond orbital (NBO) analysis.

Highlights

The production of radicals in the body is a consequence of the aerobic metabolism of the organism [1]
It is a source of hydrogen peroxide, H2O2, which in presence of released iron could form hydroxyl radical via the Fenton mechanism: Fe2+ + H2O2 󳨀→ Fe3+ + OH∙ + OH−
This study has evidenced the importance of solvent water molecules in the reactivity of superoxide radical with polyphenols

Summary

Introduction

The production of radicals in the body is a consequence of the aerobic metabolism of the organism [1]. Superoxide anion is one of the most important and biologically relevant ROS radicals in living organisms. It is formed from one-electron reduction of oxygen. The lifetime of superoxide in biological systems is typically a few seconds It can react with another superoxide anion to give hydrogen peroxide or with nitric oxide to form a very potent oxidant, peroxynitrite. O2∙− is not a strong microbicidal [1], it is essential for bacterial killing It is a source of hydrogen peroxide, H2O2, which in presence of released iron could form hydroxyl radical via the Fenton mechanism: Fe2+ + H2O2 󳨀→ Fe3+ + OH∙ + OH−

Methods

Results

Conclusion