辣椒刺盘孢新颖免疫抑制活性次生代谢产物研究

Some very important immunosuppressive drugs have been discovered from the secondary metabolites of endophytic fungi. In our previous works, we have isolated the immunosuppressive active fungi, Colletotrichum capsici, from endophytic fungi of Siegesbeckia pubescens Makino. One of the novel compounds from C. capsici displayed the immunosuppressive activity by decreasing the CD86 and MHC-Ⅱthrough the PD-1/PD-L1 pathway. HPLC analysis shows that the Colletotrichum capsici extracts are rich in secondary metabolites. So, the extracts will be phytochemically investigated in this program. Moreover, the inhibitors of the histone deacetylase (HDAC) have been introduced as effective tools for inducing transcription of silent biosynthetic gene clusters to obtain a variety of secondary metabolites. So, our objective of this project is to optimize the culture condition for obtain more kinds of immunosuppressive compounds. The structure of compounds, which isolated from the extracts by active tracking, will be determined through comprehensive spectroscopic methods. In addition, after activity evaluation of compounds, the immunosuppressive activity of some chosen compounds will be evaluated on the DC cell phenotype molecular. So, the underlying tolerogenic mechanism of the immunosuppressive activity compounds might be found.

药用植物内生真菌为特境微生物，其次生代谢产物已成为新颖活性先导化合物的重要来源。本课题组前期通过豨莶草内生真菌的分离筛选，得到了具有免疫抑制活性的内生真菌辣椒刺盘孢，分离自其发酵提取物的新颖吲哚吡嗪环骨架化合物1可经PD-1/PD-L1通路抑制小鼠树突状细胞（DC）细胞表面CD86、MHC-Ⅱ表达而发挥免疫抑制效应。辣椒刺盘孢发酵产物HPLC分析表明其次生代谢产物种类非常丰富。本项目首先拟对发酵产物中活性成分进行进一步分离；其次利用真菌易培养和组蛋白去乙酰化酶抑制剂（如软木肟酸和尼克酰胺等）干预可增加真菌沉默基因的转录而产生新代谢产物的特点，优化培养条件以产生更多活性成分，对组蛋白去乙酰化酶抑制剂干预下发酵产物活性成分进行分离。对分离自以上两种发酵产物的所有化合物进行结构鉴定和免疫抑制活性评价，选取活性最优化合物研究对DC细胞表型和PD-L1依赖的DC细胞表型的影响并探讨作用机制。

植物内生真菌为活性的天然产物的重要来源。从内生真菌次生代谢产物中寻找了具有免疫抑制活性的化合物具有重要的研究意义。本项目对豨莶草内生真菌辣椒刺盘孢不同发酵条件下的化学成分进行了研究，通过MS，HR-MS，NMR，X-Ray等方式确定了31个化合物的节后，其中4个为新化合物。通过活性筛选得到了3个具有免疫抑制活性的化合物，化合物13可诱导原代脾细胞凋亡、抑制LPS 和ConA 诱导的淋巴细胞增殖、抑制LPS 诱导的小鼠脾细胞炎性因子分泌。此外还发现化合物Citrinal B 有显著的11β-HSD1 抑制活性。部分研究结果已发表论文7 篇，其中SCI 论文5 篇。该项目丰富了辣椒刺盘孢的化学成分及活性研究。