马蔺子低聚茋类化合物调节胰岛素抵抗脂肪细胞脂代谢的机制研究

Metabolic syndrome such as obesity and type 2 diabetes are the base of cardiovascular diseases, malignant tumors, cognitive dysfunction and other chronic diseases, which seriously affect the life quality of patients. It is well known that insulin resistance (IR) is the core of glucose and lipid metabolism disorder. Lipid toxicity caused by high concentrations of free fatty acids are tightly associated with IR. Resveratrol and oligostilbenes which polymerizated from resveratrol as skeletal structures, are plant phytolysides synthesized under stress conditions. Resveratrol been deeply studied in the regulation of glucose and lipid metabolism, which was related with the activation of SIRT1 and AMPK gene. And, it has been clarified that the regulation of resveratrol is closely related to mitochondrial structure and function. Oligostilbenes are also have been found posess similar activity in recent studies. We have previously found nine of oligostilbenes from I. lacteal. Studies on the IR 3T3-L1 adipocytes have showed that oligostilbenes from I. lacteal exhibited various activities in glucose and lipid metabolism which showing a certain structure-activity relationship. Then, based on the existed research reports and our studies on the oligosilicate compounds, we intend to evaluate the bioactivity and structure-activity relationship of the oligostilbenes from I. lacteal. What’s more, the deep mechanisms will be explored through the "SIRT1-AMPK-mitochondrial biogenesis" pathway. The high fat IR C57/BL6 mice will be tested to verify the effects for the better effective compounds in vivo. We aim to find out the leading compounds with excellent effect on IR or the therapy of metabolic syndrome. This work will provide theoretical and experimental support for the found of potential compounds with important clinical values.

肥胖、Ⅱ型糖尿病等糖脂代谢紊乱是心脑血管疾病、恶性肿瘤等慢性疾病的共同病理基础。胰岛素抵抗（IR）是糖脂代谢紊乱的核心环节，高浓度游离脂肪酸所致脂毒性与IR相关。白藜芦醇及以其为骨架的低聚茋类化合物是植物在逆境条件下合成的植保素。已发现白藜芦醇能通过活化SIRT1-AMPK信号通路调控线粒体结构功能稳态改善糖脂代谢。我们前期从马蔺子中分离得到9个低聚茋类化合物并发现其明显抑制体外构建的IR脂肪细胞的脂质合成，且呈一定的构效关系。本项目拟进一步利用3T3-L1细胞分化的IR脂肪细胞，考察已有低聚茋类化合物对脂质输运、合成和代谢的影响，并从“SIRT1-AMPK-线粒体生物发生”的调节环路探讨其作用机制；进一步利用高脂喂养C57/BL6小鼠的IR模型进行有效化合物的体内验证。旨在阐明低聚茋类化合物脂代谢调控的构效关系和分子机制，为寻找到活性优异的该类化合物提供理论依据和实验支持。

肥胖、T2DM、非酒精性脂肪肝及高血脂等代谢性疾病中都伴随着严重的脂代谢紊乱，即脂肪生成增加、FFA过多蓄积、脂肪酸β氧化减弱及甘油三酯在细胞中过多积聚等从而引起细胞或者组织病变、炎症及死亡等。而现在临床上使用的用于治疗或者改善脂代谢方面的药物都存在着一定的毒副作用（剂量依赖性）。因此，寻找低毒性、治疗效果显著或者具有保肝作用的改善脂代谢紊乱的天然活性物质，将会对这些代谢性疾病的治疗与防治起到积极的作用。研究发现马蔺具有多种药理活性作用，如抗氧化、放射增敏、抗肿瘤、增强免疫力和抗生育等作用，而很少报道有关调节脂代谢及改善线粒体功能等方面的研究内容。本研究以马蔺子为原料，首先采用碱提酸沉法获得低聚茋类提取物，同时在动物和细胞水平上评价低聚茋类提取物改善脂代谢紊乱的作用。实验结果表明马蔺子低聚茋类提取物通过激活AMPK/FAS/HSL信号通路，降低脂质合成，促进脂质水解。同时低聚茋类提取物也能通过抑制转录因子PPARγ和C/EBPβ的表达而降低3T3-L1细胞中甘油三酯的合成和脂滴的积累。利用HPLC及半制备型HPLC等技术从马蔺子低聚茋类提取物中分离得到6个低聚茋类单体化合物，在细胞水平上对分离得到的单体化合物调节脂代谢作用及其机制进行了初步研究。其实验结果表明VitisinA-13b-O-glucoside、Vitisin A、Hopeaphenol和ε-viniferin通过下调PPARγ、FABP4、C/EBPα、ACC和FAS表达而抑制3T3-L1和C2C12细胞的成脂转分化。Vitisin D和Isohopeaphenol通过上调PPARγ、FABP4、C/EBPα、ACC和FAS表达，增加胞内脂滴的积累而促进3T3-L1和C2C12细胞的成脂转分化。