Tannins and related compounds. XV. A new class of dimeric flavan-3-ol gallates, theasinensins A and B, and proanthocyanidin gallates from green tea leaf (1)
Tannins and related compounds. XV. A new class of dimeric flavan-3-ol gallates, theasinensins A and B, and proanthocyanidin gallates from green tea leaf (1)
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DOI：
10.1248/cpb.31.3906
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发表时间：
1983-11
影响因子：
1.7
通讯作者：
G. Nonaka;Osamu Kawahara;I. Nishioka
中科院分区：
文献类型：
--
作者：
G. Nonaka;Osamu Kawahara;I. Nishioka
沿着与四种二聚原花色素没食子酸酯，即原飞燕草素B-2 3 '-O-没食子酸酯（IV）和原花青素B-2 3，3'-二-O-没食子酸酯（V），B-2 3 '-O-没食子酸酯（VI）和B-4 3'-O-没食子酸酯（VII），（VIII和IX），其中两个黄烷单元在B环处连接，命名为茶氨酸A和B，已经从新鲜的绿色茶叶中分离，并且它们的结构已经基于光谱学证据结合单宁酶的酶促水解而确定。还分离了三种新的单体酰化黄烷-3-醇，它们的结构类似地被表征为（-）-表没食子儿茶素3-O-对香豆酸酯（I）、（-）-表没食子儿茶素3，3 ′-二-O-没食子酸酯（II）和（-）-表没食子儿茶素3，4 ′-二-O-没食子酸酯（III）。此外，证实了已知的（-）-表儿茶素3-O-没食子酸酯（X）、（-）-表没食子儿茶素3-O-没食子酸酯（XI）、（+）-儿茶素（XII）、（-）-表儿茶素（XIII）、（-）-表没食子儿茶素（XIV）和（-）-表儿茶素3-O-（3-O-甲基）-没食子酸酯（XV）在绿色茶叶中的存在。
Along with four dimeric proanthocyanidin gallates, viz. prodelphinidin B-2 3'-O-gallate (IV) and procyanidins B-2 3, 3'-di-O-gallate (V), B-2 3'-O-gallate (VI) and B-4 3'-O-gallate (VII), two novel dimeric flavan-3-ol gallates (VIII and IX) named theasinensins A and B, in which two flavan units are linked at the B-ring, have been isolated from fresh green tea leaves, and their structures have been established on the basis of spectroscopic evidence in conjunction with enzymatic hydrolyses with tannase. Three new monomeric acylated flavan-3-ols have also been isolated, and their structures were similarly characterized as (-)-epigallocatechin 3-O-p-coumaroate (I), (-)-epigallocatechin 3, 3'-di-O-gallate (II) and (-)-epigallocatechin 3, 4'-di-O-gallate (III). In addition, the occurrence of the known (-)-epicatechin 3-O-gallate (X), (-)-epigallocatechin 3-O-gallate (XI), (+)-catechin (XII), (-)-epicatechin (XIII), (-)-epigallocatechin (XIV) and (-)-epicatechin 3-O-(3-O-methyl)-gallate (XV) in green tea leaves was confirmed.