Chlorination Increases the Persistence of Semiquinone Free Radicals Derived from Polychlorinated Biphenyl Hydroquinones and Quinones
作者:Yang Song、Garry R. Buettner、Sean Parkin、Brett A. Wagner、Larry W. Robertson、Hans-Joachim Lehmler
DOI:10.1021/jo801397g
日期:2008.11.7
Polychlorinated biphenyls (PCBs) comprise a group of persistent organic pollutants that differ significantly in their physicochemical properties, their persistence, and their biological activities. They can be metabolized via hydroxylated and dihydroxylated metabolites to PCB quinone intermediates. We have recently demonstrated that both dihydroxy PCBs and PCB quinones can form semiquinone radicals
多氯联苯(PCB)包含一组持久性有机污染物,其物理化学性质,持久性和生物活性差异很大。它们可以通过羟基化和二羟基化代谢物代谢为PCB醌中间体。我们最近证明,二羟基PCB和PCB醌均可在体外形成半醌自由基(SQ(*-))。这些半醌自由基是反应性中间体,与较低氯代PCB同类物的毒性有关。在这里,我们描述了在氯化苯环上具有不同氯化度的选定PCB代谢物的合成,例如4,4'-二氯联苯-2,5-二醇,3,6,4'-三氯联苯-2, 5-二醇,3,4,6,-三氯联苯-2,5-二醇及其相应的醌。此外,制备了两种氯化的邻氢醌,6-氯联苯-3,4-二醇和6,4'-二氯联苯-3,4-二醇。如电子顺磁共振波谱(EPR别名ESR)所检测到的,这些PCB(氢)醌很容易与氧气反应或通过配分反应生成相应的半醌自由基。在(氢)醌(氧化)环上的氯原子数越多,在接近中性pH值时所得半醌自由基的稳态水平就越高。