Selective oxidation of pyrogallol-type catechins with unripe fruit homogenate of Citrus unshiu and structural revision of oolongtheanins
Selective oxidation of pyrogallol-type catechins with unripe fruit homogenate of Citrus unshiu and structural revision of oolongtheanins
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DOI：
10.1016/j.tet.2015.03.016
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发表时间：
2015-04-29
期刊：
影响因子：
2.1
通讯作者：
Tanaka, Takashi
中科院分区：
文献类型：
--
作者：
Matsuo, Yosuke;Tadakuma, Fumiya;Tanaka, Takashi
在我们以前的化学研究的生产机制的红茶多酚，我们证明，日本梨果匀浆氧化绿色茶儿茶素轴承邻苯三酚型和儿茶酚型B-环，产生茶黄素和脱氢茶氨酸。相反，未成熟的水果匀浆的温州蜜柑选择性氧化邻苯三酚型儿茶素，只产生脱氢茶氨酸。两种匀浆的选择性的差异可能与较低的氧化还原电位的邻苯三酚型儿茶素。用C. unshiu匀浆得到两个新化合物，包括乌龙茶素前体和表没食子儿茶素4 '-O-芸香糖苷的乙醇加合物，以及茶素C、脱氢茶素E和去没食子酰基乌龙茶素。根据本研究中收集的光谱和计算数据，去没食子酰基乌龙茶素的结构应得到修正，并提出了乌龙茶素产生的机制。(C)2015爱思唯尔有限公司版权所有。
In our previous chemical study of the production mechanism of black tea polyphenols, we demonstrated that Japanese pear fruit homogenate oxidizes green tea catechins bearing pyrogallol-type and catechol-type B-rings to produce theaflavins and dehydrotheasinensins. In contrast, unripe fruit homogenate of Citrus unshiu selectively oxidizes pyrogallol-type catechins to yield only dehydrotheasinensins. The difference in the selectivity of the two homogenates is probably related to the lower redox potential of pyrogallol-type catechins. The oxidation of epigallocatechin with C. unshiu homogenate gave two new compounds, including an ethanol adduct of an oolongtheanin precursor and epigallocatechin 4'-O-rutinoside, together with theasinensin C, dehydrotheasinensin E, and desgalloyl oolongtheanin. The structure of desgalloyl oolongtheanin should be revised based on the spectroscopic and computational data collected in the current study, and a mechanism responsible for the production of oolongtheanins is also proposed. (C) 2015 Elsevier Ltd. All rights reserved.