Hsieh Sheng-Kuo, Lo Yuan-Hao, Wu Chia-Chang, Chung Tse-Yu, Tzen Jason T C
Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung, Taiwan.
Wunshan Branch, Tea Research and Extension Station, New Taipei City, Taiwan.
J Food Drug Anal. 2015 Dec;23(4):660-670. doi: 10.1016/j.jfda.2015.04.005. Epub 2015 May 28.
Teaghrelins are unique acylated flavonoid tetraglycosides found in Chin-shin oolong tea, and have been demonstrated to be promising oral ghrelin analogues. The biosynthetic pathway of teaghrelins from quercetin-3-O-rutinoside (rutin) or kaempferol-3-O-rutinoside (nicotiflorin) was proposed to comprise three enzymatic steps according to the identification of putative intermediates in Chin-shin oolong tea. In addition to the two known teaghrelins in Chin-shin oolong tea, four teaghrelin-like compounds with different attachments of glycosides were identified in various oolong teas. Molecular modeling and docking were used to evaluate theoretically whether the putative biosynthetic intermediates of teaghrelins and the four teaghrelin-like compounds could be potential candidates of ghrelin analogues. The results showed that the attachment of a coumaroyl group was crucial for these tea compounds to bind to the ghrelin receptor. However, the additional attachment of a rhamnosyl glycoside to the flavonoid backbone of teaghrelin-like compounds at C-7 significantly reduced their binding affinity with the ghrelin receptor.
茶瑞林是在金萱乌龙茶中发现的独特的酰化黄酮四糖苷，并且已被证明是有前景的口服胃饥饿素类似物。根据在金萱乌龙茶中对假定中间体的鉴定，推测茶瑞林从槲皮素-3-O-芸香糖苷（芦丁）或山奈酚-3-O-芸香糖苷（异鼠李素）的生物合成途径包括三个酶促步骤。除了金萱乌龙茶中已知的两种茶瑞林外，在各种乌龙茶中还鉴定出了四种糖苷连接方式不同的茶瑞林样化合物。利用分子建模和对接从理论上评估茶瑞林的假定生物合成中间体和四种茶瑞林样化合物是否可能是胃饥饿素类似物的潜在候选物。结果表明，香豆酰基的连接对于这些茶化合物与胃饥饿素受体结合至关重要。然而，在茶瑞林样化合物的类黄酮主链C-7位额外连接一个鼠李糖基糖苷会显著降低它们与胃饥饿素受体的结合亲和力。
