Spin trapping of polyunsaturated fatty acid-derived peroxyl radicals: Reassignment to alkoxyl radical adducts
Spin trapping of polyunsaturated fatty acid-derived peroxyl radicals: Reassignment to alkoxyl radical adducts
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DOI：
10.1016/s0891-5849(00)00456-1
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发表时间：
2001-01-15
影响因子：
7.4
通讯作者：
Mason, RP
中科院分区：
文献类型：
--
作者：
Dikalov, SI;Mason, RP
多不饱和脂肪酸（PUFA）过氧自由基在脂质氧化中起着至关重要的作用。采用自旋捕获技术的 ESR 光谱是自由基检测最直接的方法之一。 PUFA过氧自由基加合物的检测报道较多；然而，最近有报道称，在室温下尝试自旋捕获有机过氧自由基仅形成可检测量的烷氧基自由基加合物。因此，我们重新研究了亚油酸、花生四烯酸和亚麻酸衍生的 PUFA 过氧自由基的自旋捕获。慢流技术使我们能够在大豆脂氧合酶、PUFA 和自旋捕获 5,5-二甲基-1-吡咯啉 N-氧化物 (DMPO) 的混合物中获得 PUFA 衍生自由基加合物的高分辨率 ESR 光谱。然而，由于 PUFA 衍生的烷氧基加合物光谱的重叠，ESR 光谱的解释变得复杂。为了理解这些光谱，通过各种烷氧基自由基加合物对 PUFA 衍生的烷氧基加合物进行建模。我们首次合成了多种具有伯烷氧基和仲烷氧基的 DMPO 加合物。研究发现，许多先前被指定为 DMPO/过氧化自由基加合物的 ESR 光谱（基于它们与 DMPO/超氧化物自由基加合物的 ESR 光谱非常相似，并且它们对超氧化物歧化酶不敏感）实际上是烷氧基自由基加合物。我们已将 PUFA 烷基过氧自由基加合物重新分配为其相应的烷氧基自由基加合物。利用DMPO/烷氧基自由基加合物模型的超精细耦合常数，对DMPO/PUFA烷氧基自由基加合物进行计算机模拟。结果发现，捕获的、以氧为中心的 PUFA 衍生自由基是二级手性烷氧基自由基。手性碳原子的存在导致 DMPO/PUFA 烷氧基加合物的两种非对映异构体的形成。因此，尝试在室温下通过 DMPO 自旋捕获 PUFA 过氧化自由基，导致形成 PUFA 烷氧基自由基加合物。 (C) 2001 爱思唯尔科学公司。
Polyunsaturated fatty acid (PUFA) peroxyl radicals play a crucial role in lipid oxidation. ESR spectroscopy with the spin-trapping technique is one of the most direct methods for radical detection. There are many reports of the detection of PUFA peroxyl radical adducts; however, it has recently been reported that attempted spin trapping of organic peroxyl radicals at room temperature formed only alkoxyl radical adducts in detectable amounts. Therefore, we have reinvestigated spin trapping of the linoleic, arachidonic, and linolenic acid-derived PUFA peroxyl radicals. The slow-flow technique allowed us to obtain well-resolved ESR spectra of PUFA-derived radical adducts in a mixture of soybean lipoxygenase, PUFA, and the spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO). However, interpretation of the ESR spectra was complicated by the overlapping of the PUFA-derived alkoxyl radical adduct spectra. In order to understand these spectra, PUFA-derived alkoxyl radical adducts were modeled by various alkoxyl radical adducts. For the first time, we synthesized a wide range of DMPO adducts with primary and secondary alkoxyl radicals. It was found that many ESR spectra previously assigned as DMPO/peroxyl radical adducts based on their close similarity to the ESR spectrum of the DMPO/superoxide radical adduct, in conjunction with their insensitivity to superoxide dismutase, are indeed alkoxyl radical adducts. We have reassigned the PUFA alkylperoxyl radical adducts to their corresponding alkoxyl radical adducts. Using hyperfine coupling constants of model DMPO/alkoxyl radical adducts, the computer simulation of DMPO/PUFA alkoxyl radical adducts was performed. It was found that the trapped, oxygen-centered PUFA-derived radical is a secondary, chiral alkoxyl radical. The presence of a chiral carbon atom leads to the formation of two diastereomers of the DMPO/PUFA alkoxyl radical adduct. Therefore, attempted spin trapping of the PUFA peroxyl radical by DMPO at room temperature leads to the formation of the PUFA alkoxyl radical adduct. (C) 2001 Elsevier Science Inc.