黄酮类化合物与α-羟乙基过氧自由基反应的脉冲辐解研究  

Reactions between Flavonoids and α-Hydroxyl Ethyl Peroxyl Radicals:a Pulse Radiolysis Study

作　　者：张福根[1] 周瀚洋[1] 彭静[1] 吴季兰[1] 

机构地区：[1]北京大学化学与分子工程学院应用化学系,北京100871

出　　处：《物理化学学报》2013年第1期199-204,共6页Acta Physico-Chimica Sinica

基　　金：北京师范大学射线束技术与材料改性教育部重点实验室资助~~

摘　　要：由于脂质过氧化反应(LPO)是导致人体疾病(如肝炎、肝硬化、动脉硬化、脑溢血等)的主要原因,而黄酮类化合物是一类很强的过氧化反应抑制剂,因此有必要研究其化学结构与过氧化反应的关系及其抗氧化机理.本文选择α-羟乙基过氧自由基为脂质过氧自由基的模拟物,采用脉冲辐解方法研究了乙醇溶液中4种典型的黄酮类化合物(槲皮素、芦丁、儿茶素以及黄岑甙)与α-羟乙基过氧自由基的反应动力学,测得其反应活性顺序为:芦丁>槲皮素>黄岑甙>儿茶素.同时以黄酮体和邻苯二酚为黄酮类化合物不同结构特征的模型化合物,用脉冲辐解法测得二者与α-羟乙基过氧自由基的反应速率常数分别为(1.7±0.1)×106和(2.9±0.1)×105mol-1·dm3·s-1.实验结果表明,在黄酮类化合物与α-羟乙基过氧自由基的反应中,A环C5位的羟基,C环C2=C3或B-C环的大π键和B环邻二羟基共存时清除α-羟乙基过氧自由基活性最好,而且C环C2=C3或B-C环大π键的清除活性好于B环邻二羟基,同时C环是否含有C3-醣甙结构对清除作用没有明显影响.因此我们推测在黄酮类化合物抑制脂质过氧化反应过程中,起主要作用的是C环C2=C3或B-C环的大π键与脂质过氧自由基的双键加成反应.Lipid peroxidation （LPO） plays an important role in many pathological processes （such as hepatitis, hepatic sclerosis, atherosclerosis, cerebral hemorrhage and so on）, and flavonoids are considered to be effective LPO-inhibitors. Thus we investigated the relationship between the chemical structure of flavonoids and the LPO activity and the antioxidant mechanism of flavonoids. In this work, e-hydroxyl ethyl peroxyl radicals were produced from radiolysis of aerated ethanol to model lipid peroxyl radicals. By detecting the decay of e-hydroxyl ethyl peroxyl radicals in the presence of different concentrations of flavonoids using pulse radiolysis, the reaction rate constants of e-hydroxyl ethyl peroxyl radicals with quercetin, rutin, catechin, and baicalin are determined for the first time. The antioxidant activity of these flavonoids decreases in the order： rutin〉quercetin〉baicalin〉catechin. Flavone and pyrocatechol were used as model compounds for the different components in flavonoids and their reaction rate constants towards a-hydroxyl ethyl peroxyl radicals were （1.7±0.1）× 10^6 and （2.9±0.1）× 10^2 mo1-1, dm3- s-1, respectively. The effect of chemical structure on the scavenging activity towards e-hydroxyl ethyl peroxyl radicals was investigated. The coexistence of the C,-hydroxyl group in the A ring with the C2=C3 in the C ring or the conjugated double bond of the B-C ring and the catechol group in the B ring provides the best antioxidant activity. In addition, the C2=C3 in the C ring or the conjugated double bond of the B-C ring is more effective than the catechol group in the B ring, while the C3-rutinose in the C ring has no obvious effect. Therefore, we conclude that the addition reaction between double bonds with peroxyl radicals plays an important role in the antioxidant activity of flavonoids in LPO.

关 键 词：黄酮类化合物 抗脂质过氧化 脉冲辐解 动力学 化学结构 

分 类 号：O621.25[理学—有机化学]