蒙花苷的生物转化及活性代谢产物与其保肝功效的关联性

Chrysanthemum indicum L. is a traditional Chinese medicine possesses anti-inflammatory, antipyretic and antihepatitis activities. Modern pharmacology studies have demonstrated that its extract showed significant hepatic protective effect towards different liver injury caused by various reasons. Linarin, the main active constituent of Chrysanthemum indicum showed hepatic protective activity through its antioxidant, anti-inflammatory and anti-apoptosis properties. Our previous studies showed that the oral absolute bioavailability of linarin in rats was about 0.43%. After intragastrica administration of linarin, the cumulative amounts of the linarin excreted in rat urine and feces was 9.9%. That was to say, about 90% of the dose of linarin after administration were exist as uncertain structures. It is difficult to understand how linarin worked with these pharmacokinetic properties. The relevance of the metabolites and the hepatic protective effects of linarin is to be illuminated. We raised a hypothesis the hepatic protective activites of linarin was due to the combined results of linarin and its active metabolites and even the metabolites were the real substrates that worked. Thus, the aim of this study is to investigate the metabolism of linarin in detail to clarify the metabolic pathway and the possible metabolites. After the preparation of the metabolites, their hepatic protective activities will be investigated. The pharmacokinetics of linarin's metabolites will also be studied to explain the contradiction between the pharmacokinetic properties of linarin and its exact activities. This study will also provide a feasible research approach for other flavonoids with low bioavailability.

野菊花是清热解毒、泻火平肝的传统中药；药理学研究发现野菊花提取物对各种类型的肝损伤均表现出良好的保肝作用。蒙花苷作为其主要活性成分，可通过抗氧化、抑制炎症反应和细胞凋亡发挥保肝功效。申请人前期研究发现，蒙花苷生物利用度仅为0.43%；口服后从大鼠尿液和粪便中回收到的蒙花苷仅为给药剂量的9.9%；约90%的蒙花苷体内存在形式未知。蒙花苷在生物利用度极低的情况下保肝功效确切，这一现象难以理解；体内存在形式未知的那90%成分与保肝功效的关联性需要阐明。申请人在前期工作基础上提出“蒙花苷的保肝功效可能是蒙花苷及其代谢产物的综合作用结果，甚至代谢产物才是发挥药效的真正物质”的假说。本项目拟系统研究蒙花苷的生物转化，明确其体内存在形式；分离制备代谢产物并确定其保肝活性；结合活性代谢产物的体内药动学行为，解释蒙花苷生物利用度低与疗效确切之间的矛盾；为生物利用度低的中药黄酮类成分研究提供可参考的方法。

野菊花是清热解毒、泻火平肝的传统中药，蒙花苷作为其主要活性成分，具有明确的保肝功效。申请人前期研究发现，蒙花苷生物利用度仅为0.43%；约90%的蒙花苷体内存在形式未知。在此基础上，申请人提出“蒙花苷的保肝功效可能是蒙花苷及其代谢产物的综合作用结果，甚至代谢产物才是发挥药效的真正物质”的假说。针对该科学假说，本项目系统研究了蒙花苷的体内外生物转化，在大鼠灌胃给予蒙花苷后的生物样品以及肝微粒体和肠道菌群孵育体系中共鉴定出20个蒙花苷的代谢产物，包括17个保留了黄酮结构母核和3个开环裂解的代谢产物，明确了蒙花苷在大鼠体内的代谢途径主要为水解、去甲基化、葡萄糖醛酸结合、硫酸结合、木糖糖基化、甲基化和开环裂解代谢；对蒙花苷及其5个主要代谢产物刺槐素、芹菜素、间苯三酚、对羟基苯甲酸和对羟基苯甲醛进行了细胞水平和整体动物水平的保肝活性研究，发现蒙花苷及其代谢产物可通过抗炎、增强机体GSH系统、抑制自由基和脂质过氧化的产生等发挥保肝功效；药动学和肝组织分布研究结果表明，蒙花苷的主要活性代谢产物可吸收入血并分布到肝组织中，是蒙花苷保肝作用的物质基础。综上，本项目研究证明，蒙花苷的保肝功效是蒙花苷及其代谢产物的综合作用结果。