Mechanism for the Enhanced Peroxidation of Linoleic Acid by a Titanium Dioxide/Hypochlorite System

Peter McPherson; Peter M. Boyle; Bryn T. Türemen

doi:10.1016/j.bbrc.2012.11.019

Mechanism for the Enhanced Peroxidation of Linoleic Acid by a Titanium Dioxide/Hypochlorite System

Peter McPherson, Peter M. Boyle, Bryn T. Türemen

Research output: Contribution to journal › Article › peer-review

Abstract

Nanosized titanium dioxide (TiO2) is a common component of sunscreen preparations and cosmetics as it reflects UV and visible light in accordance to Rayleigh’s law. However, in aqueous environments, TiO₂ is an efficient photocatalyst, producing superoxide (O₂) and hydroxyl (HO) radicals, which are highly damaging to biomolecules. We investigated the role of TiO₂ in promoting the peroxidation of linoleic acid (LA)alone and in the presence of hypochlorous acid (HOCl). TiO₂ significantly enhanced peroxidation of LA,which was further enhanced in the presence of HOCl. This latter finding involved the formation of singlet molecular oxygen in a Russell-type mechanism appearing to involve preformed lipid hydroperoxides (LOOH). In addition to lipid peroxidation, HOCl also mediated formation of 18:1 monochlorohydrins, which in the presence of TiO₂ appeared to decompose to kinetic products which supplemented peroxidation of linoleic acid. We present a theoretical mechanism which fits the available experimental data and may partially explain the dichotomy associated with HOCls role in lipid modification.

Original language	English
Pages (from-to)	78-83
Number of pages	6
Journal	Biochemical and Biophysical Research Communications
Volume	430
Issue number	1
Early online date	20 Nov 2012
DOIs	https://doi.org/10.1016/j.bbrc.2012.11.019
Publication status	Published (in print/issue) - 4 Jan 2013

Keywords

Lipid peroxidation
Free radicals
Singlet oxygen

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10.1016/j.bbrc.2012.11.019

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title = "Mechanism for the Enhanced Peroxidation of Linoleic Acid by a Titanium Dioxide/Hypochlorite System",

abstract = "Nanosized titanium dioxide (TiO2) is a common component of sunscreen preparations and cosmetics as it reflects UV and visible light in accordance to Rayleigh{\textquoteright}s law. However, in aqueous environments, TiO2 is an efficient photocatalyst, producing superoxide (O2) and hydroxyl (HO) radicals, which are highly damaging to biomolecules. We investigated the role of TiO2 in promoting the peroxidation of linoleic acid (LA)alone and in the presence of hypochlorous acid (HOCl). TiO2 significantly enhanced peroxidation of LA,which was further enhanced in the presence of HOCl. This latter finding involved the formation of singlet molecular oxygen in a Russell-type mechanism appearing to involve preformed lipid hydroperoxides (LOOH). In addition to lipid peroxidation, HOCl also mediated formation of 18:1 monochlorohydrins, which in the presence of TiO2 appeared to decompose to kinetic products which supplemented peroxidation of linoleic acid. We present a theoretical mechanism which fits the available experimental data and may partially explain the dichotomy associated with HOCls role in lipid modification.",

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T1 - Mechanism for the Enhanced Peroxidation of Linoleic Acid by a Titanium Dioxide/Hypochlorite System

AU - McPherson, Peter

AU - Boyle, Peter M.

AU - Türemen, Bryn T.

PY - 2013/1/4

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N2 - Nanosized titanium dioxide (TiO2) is a common component of sunscreen preparations and cosmetics as it reflects UV and visible light in accordance to Rayleigh’s law. However, in aqueous environments, TiO2 is an efficient photocatalyst, producing superoxide (O2) and hydroxyl (HO) radicals, which are highly damaging to biomolecules. We investigated the role of TiO2 in promoting the peroxidation of linoleic acid (LA)alone and in the presence of hypochlorous acid (HOCl). TiO2 significantly enhanced peroxidation of LA,which was further enhanced in the presence of HOCl. This latter finding involved the formation of singlet molecular oxygen in a Russell-type mechanism appearing to involve preformed lipid hydroperoxides (LOOH). In addition to lipid peroxidation, HOCl also mediated formation of 18:1 monochlorohydrins, which in the presence of TiO2 appeared to decompose to kinetic products which supplemented peroxidation of linoleic acid. We present a theoretical mechanism which fits the available experimental data and may partially explain the dichotomy associated with HOCls role in lipid modification.

AB - Nanosized titanium dioxide (TiO2) is a common component of sunscreen preparations and cosmetics as it reflects UV and visible light in accordance to Rayleigh’s law. However, in aqueous environments, TiO2 is an efficient photocatalyst, producing superoxide (O2) and hydroxyl (HO) radicals, which are highly damaging to biomolecules. We investigated the role of TiO2 in promoting the peroxidation of linoleic acid (LA)alone and in the presence of hypochlorous acid (HOCl). TiO2 significantly enhanced peroxidation of LA,which was further enhanced in the presence of HOCl. This latter finding involved the formation of singlet molecular oxygen in a Russell-type mechanism appearing to involve preformed lipid hydroperoxides (LOOH). In addition to lipid peroxidation, HOCl also mediated formation of 18:1 monochlorohydrins, which in the presence of TiO2 appeared to decompose to kinetic products which supplemented peroxidation of linoleic acid. We present a theoretical mechanism which fits the available experimental data and may partially explain the dichotomy associated with HOCls role in lipid modification.

KW - Lipid peroxidation

KW - Free radicals

KW - Singlet oxygen

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DO - 10.1016/j.bbrc.2012.11.019

M3 - Article

SN - 0006-291X

VL - 430

SP - 78

EP - 83

JO - Biochemical and Biophysical Research Communications

JF - Biochemical and Biophysical Research Communications

IS - 1

ER -

Mechanism for the Enhanced Peroxidation of Linoleic Acid by a Titanium Dioxide/Hypochlorite System

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Keywords

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