Htet Yamin, Tennyson Andrew G
Department of Chemistry , Clemson University , Clemson , SC 29634 , USA . Email:
Department of Materials Science and Engineering , Clemson University , Clemson , SC 29634 , USA.
Chem Sci. 2016 Jul 1;7(7):4052-4058. doi: 10.1039/c6sc00651e. Epub 2016 Mar 10.
Metalloenzymes that normally perform catalytic antioxidant or radical-degrading functions, as well as small-molecule complexes that mimic them, can also exert pro-oxidant or radical-forming effects depending on the identity of the terminal reductant. Because nitroxyl radicals function as redox active cocatalysts in the aerobic oxidation of alcohols, we hypothesized that catalytic radical reduction could be achieved the oxidation of biologically-relevant alcohols. Herein we report an organoruthenium complex () that catalyzed reduction of 2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonate) radical monoanion (ABTS˙) to ABTS in phosphate buffered saline (pH 7.4) using MeOH, EtOH, i-PrOH, serine, threonine, glucose, arabinose, methyl lactate or dimethyl malate as the terminal reductant. Replacing either the C-H or O-H groups of a -CHOH- moiety resulted in the loss of ABTS˙ reducing ability. Moreover, in conjunction with an alcohol terminal reductant, was able to inhibit the oxidation of ABTS by HO and horseradish peroxidase, even after multiple successive challenges with excess HO or ABTS˙. Collectively, these results demonstrate that inhibits the oxidative formation of and catalyzes the reduction of radicals in aqueous solution oxidation of biologically-relevant alcohols.
通常执行催化抗氧化或自由基降解功能的金属酶，以及模仿它们的小分子配合物，也可根据末端还原剂的特性发挥促氧化或自由基形成作用。由于硝酰自由基在醇的需氧氧化中作为氧化还原活性助催化剂发挥作用，我们推测通过生物相关醇的氧化可以实现催化自由基还原。在此，我们报告了一种有机钌配合物（），它在磷酸盐缓冲盐水（pH 7.4）中使用甲醇、乙醇、异丙醇、丝氨酸、苏氨酸、葡萄糖、阿拉伯糖、乳酸甲酯或苹果酸二甲酯作为末端还原剂，催化将2,2'-偶氮双（3-乙基苯并噻唑啉-6-磺酸盐）自由基单阴离子（ABTS˙）还原为ABTS。取代-CHOH-部分的C-H或O-H基团会导致ABTS˙还原能力丧失。此外，与醇末端还原剂结合，即使在多次连续用过量的HO或ABTS˙挑战后，也能够抑制HO和辣根过氧化物酶对ABTS的氧化。总体而言，这些结果表明，通过生物相关醇的氧化，抑制了水溶液中自由基的氧化形成并催化了自由基的还原。
