丹参根中水苏糖积累与采后干燥过程中丹酚酸B形成相关性及其转化通路和调控机制

This application is the continuous and further research aspect of the former NSF subject. Previously, we have discovered that salvianolic acid B (SaB) of Salvia miotiorrhiza is the post-harvest drying precess; and further, we have found abundant stachynose but no accumulation of the similar salvianolic acids precursors in fresh roots of this plant. A preliminary invesgation has revealed that the degeration of stachynose and the increase of SaB showed significant positive correlation during the process of drying. We hypothesis that the mechanism of SaB formation in the drying process might be the result of remobilization and transformation of stachynose in fresh roots of this plant during dehydration stress.The aims of the present research are to uncover the solid evidences for this hypothesis. Firstly, we will detect the activities of a dozen of key enzymes and the expressions of their related genes in the metabolic pathway from stachynose to SaB during the drying process. Secondly, we are going to obtained fresh Danshen with different levels of stachynose through cultivation and analysis its relationship with contents of SaB after drying. And thirdly, we will investigate the relationship between stachyose levels in fresh roots and SaB contents in their correspond drying products during the cultivation seasons in the same location and during the harvest time from different locations. The expected results should further support our speculation that postharvest fresh plant materials, especially roots like Danshen, were still physiologically active organs and would exhibit a series of anti-dehydration mechanisms including production of related secondary metabolites at the early stage of dehydration. These results were of great value for promoting and stabilizing the quality of Danshen, and were also helpful for guiding similar investigations on other TCMs.

本项目是将结题现有基金项目的延续和深入。申请者先前发现丹酚酸B(SaB)并不是丹参根采收前积累的，而是在采后干燥过程产生的；在此基础上又从新鲜丹参中首次发现了大量水苏糖，但没有发现有预先积累的相关咖啡酸前体成分；研究初步显示干燥时该糖降解与SaB形成呈负相关。推测干燥过程中SaB的形成可能是由水苏糖转化而来。本项目拟首先从代谢途径的几个重要环节，寻找关键基因表达、酶活力及代谢流变化三方面证据，阐明干燥时从水苏糖至SaB的转化关系、通路和干燥失水调控机制；其次，通过温室栽培获得不同水苏糖积累水平的新鲜丹参；以及第三，采集同产地不同生长季节和收获期不同产地新鲜丹参，对这些新鲜以及统一方法干燥后样品中的水苏糖和SaB含量进行分析和比较，进一步阐明采收前水苏糖积累与干燥后SaB含量的关系。研究结果有可能揭示干燥过程影响丹参等宿根类药材质量的重要生物学机制，并可能成为中药质量控制研究的重要成果。

丹酚酸B是丹参药材的主要水溶性活性成分，中国药典规定其含量不得低于3.0%。前一个国家自然基金资助项目（No.30973883）已证实该成分在新鲜丹参药材中基本不含，而是在采后干燥过程中产生的，并且发现新鲜丹参根中含有大量水苏糖。本项目的主要目的，在于探讨丹酚酸B的采后形成机制，是否由根中储存的水苏糖转化而来。本研究从代谢组学和基因转录组学等系统研究，证实采后干燥过程中丹酚酸B的形成，并不是由水苏糖转化而来的。丹参生长过程中形成的丹酚酸类成分，以酯键的形式结合于木质部上，在干燥过程中失水解离出丹酚酸B，并进而进一步降解形成迷迭香酸和丹参素等小分子成分。该发现对于优质丹参药材的生产，研究丹酚酸B及其制剂的制备工艺和质量控制研究，具有重要指导意义，对于其它优质中药材的生产，也具有重要理论意义和应用价值。