Stable isotope-labeling studies on the oxidative coupling of caffeic acid via o-quinone
Stable isotope-labeling studies on the oxidative coupling of caffeic acid via o-quinone
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DOI：
10.1271/bbb.65.2613
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发表时间：
2001-12-01
影响因子：
1.6
通讯作者：
Nabeta, K
中科院分区：
文献类型：
--
作者：
Tazaki, H;Taguchi, D;Nabeta, K
邻苯二酚二聚成邻醌是邻苯二酚二聚反应的关键步骤。通过NaIO 4氧化3，4-二羟基肉桂酸（咖啡酸）的NMR分析揭示了在形成呋喃型木脂素4，8-外-双（3，4-二羟基苯基）-3，7-二氧杂双环[3.3.0]辛烷-2，6-二酮之前形成3-（3 '，4'-二氧代-1 '，5'-环己二烯基）丙烯酸（邻醌）。咖啡酸的电解和酶促氧化也产生邻醌。通过NMR和HPLC分析定量咖啡酸中邻醌的产率。一个稳定的同位素标记的木脂素的形成的研究直接证明了随机自由基耦合的半醌自由基形成的咖啡酸和邻醌。
The formation of ortho-quinone from ortho-diphenol is a key step in its dimerization. An NMR analysis of the oxidation of 3,4-dihydroxycinnamic acid (caffeic acid) by NaIO4 revealed the formation of 3-(3',4'-dioxo-1',5'-cyclohexadienyl) propenoic acid (o-quinone) prior to the formation of furofuran-type lignan 4,8-exo-bis (3,4-dihydroxyphenyl)-3,7-dioxabicyclo[3.3.0]octane-2,6-dione. Both electrolytic and enzymatic oxidation of caffeic acid also generated o-quinone. The yields of o-quinone from caffeic acid were quantified by NMR and HPLC analyses. A stable isotope-labeling study of the formation of lignans directly proved the random radical coupling of semiquinone radicals formed from a set of caffeic acid and o-quinone.