大粒车前子多糖高粘性特征内在分子机制研究

Seeds of Plantago asiatica L. has dual usages, both as medicine and food. It is approved to be as food by the Ministry of Health of China. Modern research shows that the polysaccharide from seeds of Plantago family could improve gastrointestinal function, including increasing stool weigh, water content and pH value, increasing short chain fatty acid production in the intestine, etc. The health benefits of the polysaccharide are considered to be related to its high viscosity, but the molecular mechanism of its high viscosity is still unknown, which would affect the study of its bioactivities on gut function and relative product development. The structure of the polysaccharide from seeds of Plantago asiatica L. from Ji'an, Jiangxi province, has been characterized by our group, and latest research showed that the polysaccharide's viscosity decreased significantly when calcium ion (Ca2+) or ferulic acid was removed from the polysaccharide. This project is aimed at studying the effect of Ca2+ and ferulic acid on physicochemical and conformation properties of polysaccharide from seeds of Plantago asiatica L.. We try to explore the structural relationship among the polysaccharide, Ca2+ and ferulic acid, and the effects of Ca2+ and ferulic acid on the polysaccharide's conformation in water solution, to identify the molecular mechanism of the polysaccharide's high viscosity. This research would provide the theoretical evidence for the application of polysaccharide from seeds of Plantago asiatica L.. At the same time, it would also develop the methodology of the study on the relationship among highly viscous polysaccharide, metal ion and ferulic acid.

大粒车前子是我国古代最早广泛使用的正品药材之一。现代研究证明车前子多糖可以显著改善肠道功能，如提高粪便重量和含水量、降低粪便pH值、促进结肠分泌短链脂肪酸等，这些活性和车前子多糖高粘度性质有关，但是目前车前子多糖高粘性特征的内在分子机制尚不明确，这将会极大影响车前子多糖有关肠道功能活性的深入研究和后续产品开发。本项目组已解析了江西吉安产大粒车前子多糖一级精细结构，并且发现脱除车前子多糖中的Ca2+、阿魏酸后，可显著降低其表观粘度。本课题拟在前期研究基础上，深入研究Ca2+和阿魏酸对大粒车前子多糖理化性质、溶液构象的影响，进一步从车前子多糖、Ca2+和阿魏酸三者结构关系、溶液构象相互影响等角度阐明大粒车前子多糖高粘性特征的内在分子机制。研究结果不仅可为大粒车前子多糖的构效关系研究和产品开发提供理论依据，也可为其它高粘性多糖和金属离子、阿魏酸类成分相互作用关系研究提供重要的方法学参考。

车前子多糖可以显著改善肠道功能，如提高粪便重量和含水量、降低粪便pH值、促进结肠分泌短链脂肪酸等，这些活性和车前子多糖高粘度性质有关，但是目前车前子多糖高粘性特征的内在分子机制尚不明确。本项目在前期研究基础上，利用化学分析方法结合仪器分析手段，深入研究并阐明车前子多糖拥有较高粘性特征的内在分子机制：Ca、阿魏酸、糖醛酸以及其高相对分子质量特征是大粒车前子多糖具有高粘性特征的关键因素。车前子多糖中的Ca应以二价离子形式存在（Ca2+）， Ca2+主要与连接在多糖链上的GlcA、阿魏酸相互作用，从而使得多糖链之间相互交联在一起，这种相互作用有助于车前子多糖具有较高的粘度、成胶性能以及线性链状形态。而脱除了Ca2+、阿魏酸的大粒车前子多糖，即使拥有高达100万以上相对分子质量，其粘度显著降低，但多糖链仍保留一定线性链特征（SEM形态），呈现半柔顺链的构象特征。研究结果不仅可为大粒车前子多糖的构效关系研究和产品开发提供理论依据，也可为其它高粘性多糖和金属离子、阿魏酸类成分相互作用关系研究提供重要的方法学参考。通过全体成员的努力，本项目取得了良好预期研究成果，发表了8篇学术论文，圆满完成了研究目标和任务。