Tanaka Takashi, Mine Chie, Watarumi Sayaka, Fujioka Toshihiro, Mihashi Kunihide, Zhang Ying-Jun, Kouno Isao
Department of Molecular Medicinal Sciences, Graduate School of Biomedical Sciences, Nagasaki University, Bunkyo Machi 1-14, Nagasaki 852-8521, Japan.
J Nat Prod. 2002 Nov;65(11):1582-7. doi: 10.1021/np020245k.
Production and accumulation of catechin dimer quinones during tea fermentation were chemically confirmed for the first time by trapping as phenazine derivatives. Direct treatment of the fermented tea leaves with o-phenylenediamine yielded five phenazine derivatives (8-12) of o-quinones of an epigallocatechin dimer and its galloyl esters (13-16), in which two flavan units were linked at the B-rings through a C-C bond. Atrop isomerism of the biphenyl bonds was shown to be the R configuration, suggesting that the o-quinone dimers were generated by stereoselective coupling of monomeric quinones. The total concentration of the phenazine derivatives in the o-phenylenediamine-treated tea leaves was higher than that of theaflavins. In contrast, phenazine derivatives of monomeric quinones of epigallocatechin were not isolated. When the fermented tea leaves were heated, the quinone dimers were converted to theasinensins, which are constituents of black tea, suggesting that theasinensins are generated by reduction of the quinone dimers during the heating and drying steps in black tea manufacturing.
通过捕获生成吩嗪衍生物，首次从化学角度证实了茶发酵过程中儿茶素二聚醌的产生和积累。用邻苯二胺直接处理发酵茶叶，得到了表没食子儿茶素二聚体及其没食子酰酯（13 - 16）的邻醌的五种吩嗪衍生物（8 - 12），其中两个黄烷单元通过碳 - 碳键在B环处相连。联苯键的阻转异构显示为R构型，这表明邻醌二聚体是由单体醌的立体选择性偶联产生的。邻苯二胺处理过的茶叶中吩嗪衍生物的总浓度高于茶黄素。相比之下，表没食子儿茶素单体醌的吩嗪衍生物未被分离出来。当发酵茶叶被加热时，醌二聚体转化为茶红素，茶红素是红茶的成分，这表明茶红素是在红茶制造的加热和干燥步骤中由醌二聚体还原产生的。
