State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou, Gansu 730000, China.
Org Biomol Chem. 2010 Mar 7;8(5):1058-63. doi: 10.1039/b922673g. Epub 2010 Jan 4.
alpha-Pyridoin (1, 1,2-di(2-pyridyl)-1,2-ethenediol) is a unique enediol antioxidant. To explore the detailed antioxidant mechanism of alpha-pyridoin, we synthesized alpha-pyridoin and its 5,5'- or 6,6'-bis-substituted derivatives (2-7) and compared their capacities to scavenge galvinoxyl radical (GO*) and protect human red blood cells (RBCs) from oxidative haemolysis. It was found that the compounds (5 and 6) with a methyl or methoxy group at the 5-position exhibit significantly higher GO*-scavenging and anti-haemolysis activities than other derivatives and vitamin C. Kinetic analysis of the GO*-scavenging reaction and the effect of added base on the reaction rate revealed that in ethyl acetate, the reaction occurs primarily by the direct hydrogen atom transfer (HAT mechanism). However, in ethanol that supports ionization, the kinetics of the process is mostly governed by sequential proton loss electron transfer (SPLET mechanism).
α-吡啶并（1,1,2-二（2-吡啶基）-1,2-乙二醇）是一种独特的烯二醇抗氧化剂。为了探索α-吡啶并的详细抗氧化机制，我们合成了α-吡啶并及其 5,5′-或 6,6′-双取代衍生物（2-7），并比较了它们清除半醌自由基（GO*）和保护人红细胞（RBC）免受氧化溶血的能力。结果发现，在 5 位具有甲基或甲氧基的化合物（5 和 6）对 GO的清除和抗溶血活性明显高于其他衍生物和维生素 C。对 GO清除反应的动力学分析以及添加碱基对反应速率的影响表明，在乙酸乙酯中，反应主要通过直接氢原子转移（HAT 机制）发生。然而，在支持电离的乙醇中，该过程的动力学主要受顺序质子损失电子转移（SPLET 机制）控制。
