基于肠道功能菌组的苦丁茶皂苷降血脂效应成分及作用机制研究

Occurrence and development of hyperlipidemia is causally associated with dysbacteriosis of intestinal microflora. Previous researches suggested that triterpenoid saponins from Ilex Kudingcha had strong cholesterol-lowering activity, but its therapeutic material basis and mechanism of action still need further investigation. Based on the theory of intestinal microbiome, a hypothesis was proposed: when hypercholesteremic rats orally administrated with the saponins, they will be transformed into secondary glycosides and aglycones by gut microbiota and transported to blood; and the secondary products will enhance the level of intestinal functional bacteria, restore intestinal dysbacteriosis, and therefore exert hypolipidemic activities. In the study, the differences of gut microbiota between normal and hypercholesteremic rats will be characterized rapidly by the method of ultra-high-throughput sequencing and metagenomic technologies, and the reparable effect on the gut microbiota in hypercholesteremic rats orally administrated with the saponins will be investigated, and the relevant microflora will be also identified. Then the metabolites will be separated directionally according to the results of bacterial incubation and biotransformation in vivo. Finally, the effect of repairing of intestinal bacterial structure by the metabolites will be confirmed by metagenomic technologies. Thus, the therapeutic material basis and mechanism of the saponins will be delineated. The present study will provide a new idea for researching anti-hyperlipidemia agents from TCMs, which support the reference for clarifying the material basis and mechanism of action for TCMs, acting through multi-components, multi-target and multi-channel pattern.

肠道菌群结构失调与高脂血症的发生发展存在内在的因果关系。前期研究表明，苦丁茶皂苷具有良好的降血脂效果，但仍需深入研究其药效物质基础和作用机制。本课题以肠道菌群为切入点，提出假说：苦丁茶皂苷口服后，被高脂血症大鼠肠道菌群代谢为次生苷或苷元吸收入血，并提高菌群中功能菌组的含量水平，恢复失调菌群结构谱，从而发挥治疗高脂血症的作用。采用高通量测序技术,结合元基因组学快速表征正常与高血脂症大鼠肠道菌群的结构谱差异，筛选鉴定与之相关的肠道功能菌组，并探讨苦丁茶皂苷对失调肠道菌群的恢复作用；基于体外功能菌组孵育和体内菌群转化，靶向分离苦丁茶皂苷的菌群代谢产物；最后进一步应用元基因组学验证上述代谢产物对功能菌组的修复作用，从而阐明苦丁茶皂苷降血脂的药效物质基础与作用机制。课题的完成，将为从中药中寻找降脂药物提供一种研究思路，也为中药“多成分、多靶点、多途径”作用的物质基础和作用机理的阐明提供借鉴。

肠道菌群结构失调与高血脂症的发生发展存在内在的因果关系。前期研究表明，苦丁茶皂苷具有良好的降血脂效果，但仍需深入研究其药效物质基础和作用机制。本课题以肠道菌群为切入点，提出假说：苦丁茶皂苷口服后，被高血脂症大鼠肠道菌群代谢为次生苷或苷元吸收入血，并提高菌群中功能菌组的含量水平，恢复失调菌群结构谱，从而发挥治疗高血脂症的作用。课题组首先对苦丁茶冬青的化学成分以及药理作用进行了详细的文献调研；应用多种柱色谱技术，制备了苦丁茶皂苷药效部位；构建了基于UPLC-MS快速分析和表征苦丁茶皂苷组成特征的分析方法；建立了高血脂症大鼠模型；比较了正常大鼠、高血脂症大鼠模型组和苦丁茶皂苷给药组大鼠肠道菌群结构谱差异；探讨了基于体内外肠道菌群的苦丁茶皂苷主要成分苦丁茶皂苷D的代谢转化情况及其降脂减肥机制；苦丁茶皂苷在高血脂症大鼠体内的代谢转化情况。研究发现，高血脂症大鼠肠道菌群结构谱异于正常大鼠；苦丁茶皂苷对于该失调肠道菌群具有修复调整作用，主要表现为肠道菌群多样性增加，有益菌数量升高；经正常大鼠肠道菌群转化后，苦丁茶皂苷D主要以次生苷及极微量苷元吸收入血，并可通过激活AMPK通路产生降脂减肥作用；苦丁茶皂苷在高血脂症大鼠体内以次生苷及极微量苷元吸收入血，产生降血脂的作用。上述研究结果表明，苦丁茶皂苷主要以次生苷及极微量的苷元吸收入血，通过修复高血脂症大鼠失调肠道菌群，降低大鼠体内炎性因子和提高短链脂肪酸水平，从而产生降血脂的作用。课题的完成，将为中药成分的代谢转化研究提供一种思路，也为中药“多成分、多靶点、多途径”作用的物质基础和作用机理的阐明提供借鉴。