杂色曲霉中新颖天然PPARγ激动剂的发现及其降糖作用的研究

PPARγ mainly expresses in adipose tissue and immune system and is closely related to the differentiation of adipose cell, body immunity and insulin resistance. It is the target molecule of thiazolidinedione, an insulin-sensitized hypoglycemic drug. therefore, PPARγ is regarded as the hot therapeutic target for studying and treating diabetic metabolic syndromes in recent years. In the previous study, asperversiamide I, a novel linearly prenylated indole alkaloid, was isolated from the endophytic Aspergillus versicolor F210 from Hypericum sampsonii Hance, and showed a significant PPARγ activation activity via computer Reverse Virtual Screening and evaluation of biological activity in vitro. The applicant proposes to adopt the methods of HPLC-DAD and LC-MS in real-time, quickly and accurately to discover more linearly prenylated indole alkaloids by amplifying the rice fermentation and applying OSMAC strategy to liquid culture of A. versicolor F210. Furthermore, methods of molecular biology, cell biology and molecular pharmacology will be implemented to find out the compound with the best PPARγ activation activity and the mechanism of hypoglycemic activity by activating PPARγ will be elucidated. The possibility of the best PPARγ activation activity as a lead compound and a patent drug will be further evaluated, and this project provides a scientific basis for the discovery of drugs for the treatment of diabetes.

PPARγ主要表达于脂肪组织及免疫系统，与脂肪细胞分化、机体免疫及胰岛素抵抗关系密切，是胰岛素增敏类降糖药噻唑烷二酮作用的靶分子，为近年来研究和治疗糖尿病代谢综合征的热门靶点。申请者前期在对元宝草内生菌杂色曲霉次生代谢产物的研究中，通过提取分离、结构鉴定、计算机虚拟筛选以及体外生物活性测试等方法和手段发现一个结构新颖且具有显著PPARγ激活活性的线型异戊烯基吲哚生物碱asperversiamide I。本项目拟对该菌大米固体放大培养和运用OSMAC策略液体培养，采用HPLC-DAD和LC-MS方法实时、快速、精准地发现更多同类物。并采用分子生物学、细胞生物学和分子药理学等方法寻找出PPARγ激活活性最优的化合物，阐明其通过激活PPARγ发挥降糖活性的作用机制，深入评价该化合物作为先导化合物和成药的可能性，为发现治疗糖尿病的药物提供科学依据。

天然产物是药物开发的重要源泉之一，微生物代谢的天然产物因具有新颖的结构及不可预期的显著活性而成为天然药物化学的研究热点。本项目前期从海洋来源和植物内生的杂色曲霉中均发现了系列线型异戊烯基吲哚生物碱新化合物，初步活性研究发现，asperversiamide I 显示出较好的PPARγ激动活性从而具有降糖活性潜力。本项目拟通过对植物内生菌杂色曲霉进行大米放大培养，充分挖掘该真菌中的异戊烯基吲哚生物碱类次级代谢产物，以期从中发现降糖先导小分子化合物。通过该项目的实施，我们从2种来源的杂色曲霉的发酵产物中分离、鉴定得到了以生物碱和倍半萜为主的多种类型化合物36个，其中新化合物18个。在深入的活性研究中发现，线型异戊烯基吲哚生物碱未表现出理想的降糖活性。作为活性补充，项目对所分离的大部分化合物进行了细胞毒等活性研究，部分生物碱、杂萜和倍半萜显示出了显著的活性，值得进一步的深入研究。综合以上研究结果，该项目的顺利实施丰富了杂色曲霉的活性代谢产物的种类及突出了新颖代谢产物的研究价值，对挖掘微生物中新颖活性天然产物具有积极的意义。