MCLA为化学发光探针测定氧化低密度脂蛋白中维生素C诱导的单线态氧产生

以一种海萤荧光素类似物MCLA〔2 methyl 6 (p methoxyphenyl) 3,7 dihydroimidazo [1,2 a]pyrazin 3 one〕作为高灵敏且有选择性的化学发光探针 ,用化学发光的方法直接观测到了少量Cu2 氧化的低密度脂蛋白 (Ox LDL)中维生素C诱导的单线态氧 (1O2 )的产生。实验中通过叠氮化钠 (NaN3 )对MCLA介导的化学发光的猝灭作用进一步证实了上述体系中1O2的形成。根据实验观察的结果 ,分析了这一体系中1O2 形成的可能途径 ,认为首先是维生素C将Cu2 转变为还原态 ,而自身失去一个电子转变为维生素C自由基 ,从而刺激了过氧自由基和烷氧自由基的形成 ,过氧自由基的双分子反应很可能就是体系内1O2 产生的反应机制

Detection of Vitamin C-induced Singlet Oxygen Formation in Oxidized LDL Using MCLA as A Chemiluminescence Probe

In this study, it was observed that addition of vitamin C (vit C) to oxidized low-density lipoprotein (Ox-LDL) by cupric ions (Cu 2 ) could result in the formation of singlet oxygen ( 1O 2). In experiments, 1O 2 was detected by chemiluminescence method using a Cypridina luciferin analog, 2-methyl-6-(p-methoxyphenyl)-3, 7-dihydroimidazo [1, 2-a] pyrazin-3-one (MCLA), as a selective and sensitive chemiluminescence probe. Additional experimental evidence for the formation of 1O 2 came from the quenching effect of sodium azide (NaN 3) on vit C-induced chemiluminescence in the reaction mixture of LDL-Cu 2 -MCLA. Analysis based on the experimental results demonstrated the plausible reaction mechanism is that vit C first converts Cu 2 to its reduced state and vit C becomes vit C radical itself, thereby stimulating the formation of peroxyl and alkoxyl radicals, and bimolecular reaction of peroxyl radicals results in 1O 2 production in the systems studied.