桑叶经霜品质变化机理相关研究

“Mulberry leaves after frost” are commonly used in traditional Chinese medicine to evacuate wind-heat, clear away lung-heat and moisten dryness. Those mulberry leaves have superior quality compared to the leaves before frost. But the effects of the frost on the functional components in mulberry leaves and its scientific connotation of medical characterization are not clearly now. Based on previous research, we suggest: That functional components in mulberry leaves change dynamically after the frost, is mainly due to the effects of ambient temperature changes around the frost on the expression and activities of the metabolic enzymes in biosynthesis of mulberry leaves. So the effective compositions of mulberry leaves change, and that appropriate ratios of various functional components after the frost are the basis for the efficacy. Based on this hypothesis, in this project we will study the dynamic change rule of functional components in mulberry leaves with the plant metabonomics technology. We will evaluate the functions of mulberry leaves in evacuating wind-heat, clearing away lung-heat and moistening dryness with a rabbit fever model, and a guinea pig cough model induced by electric stimulation. We will analyze the correlation between dynamic changes of functional substance groups and biological effects of mulberry leaves with an artificial neural network model. With the studies on plant biosynthetic pathways and metabonomics technology, we wish to explain the transformation mechanism of chemical components in mulberry leaves around the frost, and to support the scientific evidence for harvesting the mulberry leaves after frost.

“霜桑叶”品质上乘、药性俱佳为中医临床疏散风热、清肺润燥常用中药。但经霜过程对桑叶功效物质的影响及其药性表征的科学内涵亟待阐明。本项目在前期大量研究工作基础上提出：桑叶经霜前后功效物质组发生动态变化，主要是由于经霜前后环境温度变化影响桑叶生物合成途径中代谢酶的活性与表达，从而使桑叶功效成分表征发生变化，而经霜后适宜的功效成分组合是霜桑叶的药效物质基础。基于该假说本项目应用植物代谢组学等技术，研究桑叶功效物质组的动态变化规律；应用家兔致热源非热限性发热模型、豚鼠电刺激引咳模型，评价经霜前后桑叶疏散风热、清肺润燥的功效；应用人工神经网络等数学模型，分析桑叶功效物质组动态变化与其生物效应之间的相关性；运用生物学技术结合植物生源途径和代谢组学研究桑叶经霜前后化学组分转化的机制，最终阐明桑叶经霜过程对其功效物质组影响的科学内涵，为桑叶经霜采收的合理性提供科学依据。

“霜桑叶”品质上乘、药性俱佳为中医临床疏散风热、清肺润燥常用中药。但经霜过程对桑叶功效物质的影响及其药性表征的科学内涵亟待阐明。本项目在前期大量研究工作基础上提出：桑叶经霜前后功效物质组发生动态变化，主要是由于经霜前后环境温度变化影响桑叶生物合成途径中代谢酶的活性与表达，从而使桑叶功效成分表征发生变化，而经霜后适宜的功效成分组合是霜桑叶的药效物质基础。基于该假说本项目应用植物代谢组学等技术，研究桑叶功效物质组的动态变化规律，发现经霜后黄酮、酚酸类成分升高，生物碱类成分降低；应用现代药理模型，评价经霜前后桑叶清肺润燥的功效，结果为经霜后桑叶清肺润燥的功效优于未经霜桑叶；应用分子对接技术分析了桑叶功效物质组与其生物效应之间的相关性；运用生物学技术结合植物生源途径和代谢组学研究了经霜对桑叶黄酮、酚酸类成分合成途径中关键酶基因PAL、4CL、CHS、UFGT、HCT和C3'H表达水平的影响，结果表明霜降节气后在11月达到较高值，与黄酮酚酸成分含量呈正相关、气温呈负相关，提示低温可能诱导这些酶基因的表达水平，有利于黄酮酚酸类物质的积累；并对黄酮酚酸类成分生合成途径中关键酶基因MaUFGT、MaHCT和MaC3'H基因进行了克隆、表达和功能验证；采用人工模拟气候，研究了温度对桑叶黄酮酚酸合成途径中关键酶基因表达和成分积累的影响，研究证实低温可诱导桑叶黄酮、绿原酸合成途径中关键酶基因PAL、UFGT、4CL、CHS及C3'H的表达，有利于黄酮类及绿原酸成分的积累。本结果为阐明桑叶经霜过程对其功效物质影响和桑叶经霜采收的合理性提供科学依据。.本项目发表论文18篇，其中 SCI 收录9篇，已接收SCI文章1篇；培养硕士研究生 3名，博士生2名。