茶叶中经A环亲核加成形成的新型儿茶素的分离、结构鉴定、生成机制和神经细胞保护活性及其机制研究

儿茶素是决定茶叶品质和健康功效的最重要成分，相关研究一直是茶叶化学研究的重点。以往茶叶儿茶素的研究主要集中于基于反应活泼的B环进行的，如氧化聚合而形成的茶黄素、B环裂解形成的降解产物。近年来研究发现了因儿茶素A环的6、8位富含电子可与咖啡酸等酚酸或茶氨酸等亲核加成形成了新型儿茶素。我们最新研究发现紫鹃茶鲜叶及其绿茶成品中均存在以上成分。因此，本项目应用我们自主建立的大型茶叶化合物数据库，对这些新型儿茶素的NMR波谱规律进行总结；以组份的LC-HRMS和NMR图谱信息为导向，定向快速地从茶叶中发现这些新型儿茶素，研究其结构、可能的生成机制以及对神经细胞的保护作用及可能的作用机制。同时研究它们在绿茶加工过程的变化及其化学机制。从而深入理解茶树中重要次生代谢产物儿茶素、茶氨酸及酚酸之间的相互作用和相关机制及绿茶加工品质形成的物质基础，进一步促进茶叶综合利用特别是其在食品、医药等领域的应用及开发。

Catechins are the most important components contributing to the quality and health benefits of tea. Therefore, catechins have been the focus of tea chemistry. There are many kinds of catechins in tea, among which phenypropanoid substituted catechins and flavoalkaloids are seldom studied. Our latest study found the presence of the above two types of components in Zijuan sundry green tea. So,this project is proposed to isolate and identify novel catechins from Ziuan green tea based on the use of the large-scale tea compound database (TMDB) established by the applicant as well as the most advanced chromatography and NMR technologies. Guided by the summary of the LCMS and NMR principle rules of the two kinds of catechins in tea, the target compounds can be quickly followed by HPLC-HRMS and NMR tested on the mixture (crude extracts and fractions of the tea). Then the novel catechins were further isolated by advanced liquid chromatography and identified by LC ESI-HR-MS and NMR spectra. The structure of the two kinds of components together with their possible biosynthetic pathway will be explored as well as the mechanisms for their protective effects from injury of nerve cell induced by H2O2.