Flavonoid Oxidation by the Radical Generator AIBN: A Unified Mechanism for Quercetin Radical Scavenging
作者:Venkat Krishnamachari、Lanfang H. Levine、Paul W. Paré
DOI:10.1021/jf020045e
日期:2002.7.1
nucleophiles revealed that two of the products, namely the substituted benzofuranone (2) and the depside (4), are generated from a common carbocation intermediate. Indirect evidence for the operation of a cyclic concerted mechanism in the formation of the dimeric product (3) is provided. The identification of these products supports the model that the principal site of scavenging reactive oxygen species (ROS)
槲皮素(五羟基黄酮)与过氧自由基发生剂2,2'-偶氮二异丁腈(AIBN)反应生成的四种氧化的类黄酮衍生物通过色谱法分离,并通过NMR和MS分析鉴定。化合物包括2-(3,4-二羟基苯甲酰基)-2,4,6-三羟基-3(2H)-苯并呋喃酮(2); 1,3,11a-三羟基-9-(3,5,7-三羟基-4H-1-苯并吡喃-4-基-2-基)-5a-(3,4-二羟基苯基)-5,6,11-六氢-5,6,11-三氧萘并蒽-12-一(3); 2-(3,4-二羟基苯甲酰氧基)-4,6-二羟基苯甲酸(4); 和3,4-二羟基苯基乙醛酸甲酯(5)。在不同氢离子浓度和外部亲核试剂下的产物比率表明,两种产物,即取代的苯并呋喃酮(2)和深度(4),是从一种常见的碳正离子中间体生成的。提供了在二聚产物(3)的形成中循环协同机制起作用的间接证据。这些产物的鉴定支持以下模型:槲皮素中清除活性氧(ROS)的主要位点是B环中的邻二羟基取代基以及C环烯烃键。