Syu Kai-Yang, Lin Chih-Li, Huang Hsiu-Chen, Lin Jen-Kun
Graduate Institute of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, Taipei, Taiwan.
J Agric Food Chem. 2008 Sep 10;56(17):7637-43. doi: 10.1021/jf801795m. Epub 2008 Jul 25.
Dabsyl chloride (dimethylaminoazobenzene sulfonyl chloride), a useful chromophoric labeling reagent for amino acids and amines, was developed in this laboratory in 1975. Although several methods have been developed to determine various types of amino acids, a quick and easy method of determining theanine, GABA, and other amino acids has not been developed in one HPLC system. In this paper are analyzed the free amino acid contents of theanine and GABA in different teas (green tea, black tea, oolong tea, Pu-erh tea, and GABA tea) with a dabsylation and reverse phase high-performance liquid chromatography (HPLC) system coupled with a detector at 425 nm absorbance. Two reverse phase columns, Hypersil GOLD and Zorbax ODS, were used and gave different resolutions of dabsyl amino acids in the gradient elution program. The data suggest that the tea source or the steps of tea-making may contribute to the theanine contents variations. High theanine contents of high-mountain tea were observed in both green tea and oolong tea. Furthermore, the raw (natural fermented) Pu-erh tea contained more theanine than ripe (wet fermented) Pu-erh tea, and the GABA contents in normal teas were generally lower than that in GABA tea.
二甲基氨基偶氮苯磺酰氯（Dabsyl chloride）是一种用于氨基酸和胺类的有用发色标记试剂，于1975年在本实验室研发。尽管已经开发了几种方法来测定各种类型的氨基酸，但尚未在一个高效液相色谱（HPLC）系统中开发出一种快速简便的测定茶氨酸、γ-氨基丁酸（GABA）和其他氨基酸的方法。本文采用重氮基化和反相高效液相色谱（HPLC）系统，并结合425nm吸光度检测器，分析了不同茶叶（绿茶、红茶、乌龙茶、普洱茶和GABA茶）中茶氨酸和GABA的游离氨基酸含量。使用了两根反相柱，Hypersil GOLD和Zorbax ODS，在梯度洗脱程序中对重氮基化氨基酸给出了不同的分离度。数据表明，茶叶来源或制茶步骤可能导致茶氨酸含量的变化。在绿茶和乌龙茶中均观察到高山茶的茶氨酸含量较高。此外，生（自然发酵）普洱茶比熟（湿发酵）普洱茶含有更多的茶氨酸，普通茶叶中的GABA含量通常低于GABA茶中的含量。
