Multi-faceted Reactivity of Alkyltellurophenols Towards Peroxyl Radicals: Catalytic Antioxidant Versus Thiol-Depletion Effect
Multi-faceted Reactivity of Alkyltellurophenols Towards Peroxyl Radicals: Catalytic Antioxidant Versus Thiol-Depletion Effect
复制标题
DOI：
10.1002/chem.201300451
复制
发表时间：
2013-06-01
影响因子：
4.3
通讯作者：
Engman, Lars
中科院分区：
文献类型：
--
作者：
Amorati, Riccardo;Valgimigli, Luca;Engman, Lars
羟基芳基烷基碲化物在有机溶液和水两相体系中均是有效的抗氧化剂。它们通过非常规机制与ROO反应。自由基的反应速率常数在303 K时高达107 M1 s ~（-1），优于一般的酚类化合物。反应通过氧原子转移到碲，然后氢原子转移到所得RO来进行。从酚OH的自由基。反应速率不反映环取代基的电子性质，并且由于反应发生在溶剂笼中，当OH和TeR基团具有邻位排列时，淬灭更有效。在硫醇的存在下，羟基芳基烷基碲化物作为催化抗氧化剂对氢过氧化物（模拟谷胱甘肽过氧化物酶）和过氧自由基。过氧自由基和氢过氧化物的高效率淬灭在正常细胞条件下可能是有利的，但当硫醇浓度低时是促氧化的（硫醇耗尽）。
Hydroxyaryl alkyl tellurides are effective antioxidants both in organic solution and aqueous biphasic systems. They react by an unconventional mechanism with ROO. radicals with rate constants as high as 107M1s1 at 303K, outperforming common phenols. The reactions proceed by oxygen atom transfer to tellurium followed by hydrogen atom transfer to the resulting RO. radical from the phenolic OH. The reaction rates do not reflect the electronic properties of the ring substituents and, because the reactions occur in a solvent cage, quenching is more efficient when the OH and TeR groups have an ortho arrangement. In the presence of thiols, hydroxyaryl alkyl tellurides act as catalytic antioxidants towards both hydroperoxides (mimicking the glutathione peroxidases) and peroxyl radicals. The high efficiency of the quenching of the peroxyl radicals and hydroperoxides could be advantageous under normal cellular conditions, but pro-oxidative (thiol depletion) when thiol concentrations are low.