Theaflavins, the orange–red pigments contained in black tea, have attracted attention as a result of their health-promoting effects. However, their synthetic preparation, in which the enzymatic oxidation of catechol-type catechin is followed by the quinone-induced oxidative dimerization of selectively combined catechol- and pyrogallol-type catechins, provides only a low yield. In the present study, we found that a 1-octanol/buffer biphasic system improved the yield of theaflavin 3-gallate in a tyrosinase-catalyzed synthetic reaction with (−)-epicatechin and (−)-epigallocatechin gallate. When the enzymatic reaction proceeded in a buffer solution, oxidized (−)-epigallocatechin gallate was preferentially used for self-dimerization. However, self-dimerization was suppressed in the octanol phase, allowing oxidized (−)-epigallocatechin gallate to participate in coupling with (−)-epicatechin quinone, leading to effective production of theaflavin 3-gallate. Furthermore, the preferential localization of theaflavin 3-gallate in the octanol phase prevented (−)-epicatechin-quinone-induced degradation.

中文翻译：

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1-辛醇/缓冲液双相系统中酪氨酸酶催化与（-）-表儿茶素和（-）-表没食子儿茶素没食子酸酯的高效合成合成茶黄素3-没食子酸酯

茶黄素是红茶中的橙红色色素，由于其促进健康的作用而引起了人们的关注。然而，他们的合成制备方法，其中邻苯二酚型儿茶素的酶促氧化，随后由苯醌诱导的选择性结合的邻苯二酚和邻苯三酚型儿茶素的氧化二聚化，仅提供了低产率。在本研究中，我们发现1-辛醇/缓冲液双相系统在酪氨酸酶催化的（-）-表儿茶素和（-）-表没食子儿茶素没食子酸酯的合成反应中提高了茶黄素3-没食子酸酯的收率。当酶反应在缓冲溶液中进行时，氧化的（-）-表没食子儿茶素没食子酸酯优先用于自二聚。但是，在辛醇相中自二聚被抑制，使氧化的（-）-表没食子儿茶素没食子酸酯参与与（-）-表儿茶素醌的偶合，导致茶黄素3-没食子酸酯的有效生产。此外，茶黄素3-没食子酸酯在辛醇相中的优先定位阻止了（-）-表儿茶素-醌诱导的降解。