Ferrari-Iliou R, D'Arcy-Lameta A, Iliou J P, Thi A T, Monteiro de Paula F, Da Silva J V, Mazliak P
Laboratoire d'Ecologie Générale et Appliquée, Université Paris 7, France.
Biochim Biophys Acta. 1993 Feb 10;1166(1):48-54. doi: 10.1016/0005-2760(93)90282-e.
In vitro lipid peroxidation, induced by reactive oxygen species photochemically generated, was carried out on purified alpha-linolenic acid (18:3(n - 3)) and on bean leaf total lipophilic extracts. The photosensitizer used was meso-tetraphenylporphine. The time-course of the reaction was evaluated by ultraviolet (UV) spectra analysis. The 18:3(n - 3) photoperoxidation kinetics comprised three steps: monohydroperoxidation, characterized by the appearance of conjugated diene patterns; dihydroperoxidation characterized by the appearance of conjugated triene patterns, oxidative cleavage of the mono- and dihydroperoxides, characterized by the disappearance of conjugated patterns. In contrast, for hydrated plant total lipophilic extract photoperoxidation, conjugated pattern appearance was slow and the maximum plateau was not obtained. In order to explain plant extract behaviour, we tested the effects of beta-carotene and quercetin (important components of the chloroplast membrane) on the time-course of 18:3(n - 3) photoperoxidation. The first step was inhibited by beta-carotene implying that type II photoperoxidation involving singlet oxygen (1O2) was predominant. Whilst the two last steps were inhibited by quercetin implying that type I photoperoxidation involving free radicals, prevailed. Since 18:3(n - 3) foliar content decreased under water deficit, we tested the behaviour of total lipophilic extracts from droughted plant leaves in presence of reactive oxygen species. In the case of droughted plants, the maximum of conjugated diene patterns was attained later than for hydrated plants, suggesting that drought affects the resistance capability of total lipophilic extracts from bean leaves to lipid photoperoxidation.
通过光化学产生的活性氧诱导体外脂质过氧化反应，该反应在纯化的α-亚麻酸（18:3(n - 3)）和豆叶总亲脂性提取物上进行。所用的光敏剂是中-四苯基卟啉。通过紫外光谱分析评估反应的时间进程。18:3(n - 3)的光过氧化动力学包括三个步骤：单氢过氧化，其特征是共轭二烯模式的出现；双氢过氧化，其特征是共轭三烯模式的出现；单氢过氧化物和双氢过氧化物的氧化裂解，其特征是共轭模式的消失。相比之下，对于水合植物总亲脂性提取物的光过氧化，共轭模式的出现较慢且未达到最大平台期。为了解释植物提取物的行为，我们测试了β-胡萝卜素和槲皮素（叶绿体膜的重要成分）对18:3(n - 3)光过氧化时间进程的影响。第一步被β-胡萝卜素抑制，这意味着涉及单线态氧（1O2）的II型光过氧化占主导。而最后两步被槲皮素抑制，这意味着涉及自由基的I型光过氧化占主导。由于水分亏缺下18:3(n - 3)的叶片含量会降低，我们测试了干旱植物叶片总亲脂性提取物在活性氧存在下的行为。在干旱植物的情况下，共轭二烯模式的最大值比水合植物出现得晚，这表明干旱会影响豆叶总亲脂性提取物对脂质光过氧化的抵抗能力。
