Kinetics of photoperoxidation of arachidonic acid: Molecular mechanisms and effects of antioxidants |
| |
Authors: | Jean-Pierre Iliou David Jourd'heuil Frédéric Robin Bernard Serkiz Pascale Guivarc'h Jean-Paul Volland Jean-Paul Vilaine |
| |
Affiliation: | (1) Institut de Recherches Servier, 11 rue des Moulineaux, 92150 Suresnes, France |
| |
Abstract: | The kinetics of photoperoxidation of 1−14C]arachidonic acid (20∶4n−6) at 1.32 mM was studied either with the unsaturated fatty acid alone or in the presence of 10μM
of antioxidants and/or inhibitors of eicosanoid metabolism. The photosensitizer used wasmeso-tetraphenylporphine. The time-course of the reactions was followed by ultraviolet spectral analysis, thiobarbituric acid
reactivity and high-performance liquid chromatographic analysis of aliquots sampled every 15 min during the 4 h of irradiation.
The kinetics of photoperoxidation of 20∶4n−6 can be divided into three main successive steps: (i) monohydroperoxidation, characterized
by the appearance of conjugated diene patterns and monohydroperoxidized 20∶4n−6; (ii) secondary oxidation characterized by
polyoxygenated products such as dihydroperoxidized 20∶4n−6 possessing conjugated triene patterns; and (iii) the disappearance
of conjugated patterns and the oxidative cleavage of the products of the two first steps into aldehydic molecules reacting
with thiobarbituric acid. During the first 90 min of irradiation, the mechanism of monohydroperoxidation (step one) is purely
or predominantly type II photoperoxidation involving only singlet oxygen. This step was inhibited by β-carotene and by BW755C
(3-amino-1-3-trifluoromethylphenyl]2-pyrazoline). In contrast, the reactions involved in the second and third steps were
predominantly type I photoperoxidation involving radical mechanisms. These latter steps were inhibited by β-carotene, BW755C,
vitamin E and probucol. Indomethacin and 5,8,11,14-eicosatetraynoic acid did not alter 20∶4n−6 photoperoxidation. Thisin vitro model of lipid photoperoxidation allows the screening of antioxidants in accordance with their singlet oxygen quenching and/or
free radical scavenging properties. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|