岗松混源萜类化合物的TNF-α抑制构效关系及作用机制研究

Baeckea frutescens (Myrtaceae) has long been used as a folk herbal medicine in south China for treating enteritis and diarrhea. Preliminary phytochemical investigation of the petroleum ether extract of the aerial parts of B. frutescens resulted in the isolation and identification of series of novel meroterpenoids with potent TNF-α inhibitory activity in vitro. They were found as the natural TNF-α inhibitors derived from meroterpenoids for the first time. TNF-α was the new target for treating inflammatory bowel disease. The inhibition of TNF-α could block TNF-α-mediated NF-κB inflammatory signaling pathways. Furthermore, the HPLC/DAD-Q/TOF-MS analysis of the petroleum ether extract indicated that the title plant still contains unknown bioactive meroterpenoids. The objective of this study is to further investigate the bioactive monoterpene-based meroterpenoids, under the guidance of the established analytic method, and evaluate for their TNF-α inhibitory activities. Then, diversity-oriented synthesis and structural modification of bioactive meroterpenoids with various privileged skeletons will be performed based on biomimetic synthesis and combinatorial chemistry strategy. This thesis mainly focuses on the studies of the structure-activity relationships and the mechanism of meroterpenoids as TNF-α inhibitors. This research will provide basis for the development of new anti-inflammatory bowel disease agents with high efficiency and low toxicity based on TNF-α inhibition.

桃金娘科药用植物岗松（Baeckea frutescens）为我国岭南民间地区治疗肠炎腹泻的常用中药。本课题前期研究发现从岗松枝叶石油醚萃取部位分离得到的新颖结构混源萜类特征性成分体外具有显著的TNF-α抑制作用，为首次发现的天然混源萜类TNF-α抑制剂。TNF-α抑制为炎症性肠病治疗的的新型靶点，将阻断TNF-α介导的NF-κB等炎症信号通路。通过HPLC/DAD-Q/TOF-MS分析，发现该部位还含有较大量未被分离得到的新颖混源萜活性成分。本项目拟在前期研究工作基础上，进一步对岗松枝叶中TNF-α抑制活性较强的间苯三酚杂单萜类混源萜进行靶向分离、鉴定，评价该类化合物的TNF-α抑制活性，基于仿生策略和组合化学对不同优势骨架类型的活性混源萜进行多样性合成和结构改造，深入开展TNF-α抑制构效关系与作用机制研究，为新型基于TNF-α抑制的高效、低毒治疗炎症性肠病药物的研究开发奠定基础。

桃金娘科岗松属药用植物岗松Baeckea frutescens L.为我国岭南民间地区常用清热解毒中药，临床适用于治疗跌打瘀肿、黄疸型肝炎、肠炎腹泻、风湿关节痛、虫蛇咬伤等炎症感染性疾病，疗效确切，但其抗感染药效物质尚不明确。本项目对岗松枝叶混源萜类特征性成分进行系统的化学结构与抗感染功能评价研究。采用色谱及波谱技术 (NMR, HR-ESI-MS, 单晶X-ray, 量子化学ECD计算)，从岗松枝叶中分离鉴定12个混源萜类化合物。基于生源合成途径推导，以廉价易得的间苯三酚为起始原料，首次通过DIBAL-H催化环外羰基选择性还原、迈克尔加成、TEMP/Ag2O联合催化的氧化[4+2]环合及水相Diels-Alder点击化学反应等以较高收率完成了岗松tasmanone来源的系列天然混源萜baefrutones A-D, baeckenon B, frutescones A, D-F的仿生全合成研究。采用LPS诱导RAW264.7细胞释放NO炎症模型，考察岗松混源萜的体外抗炎活性 (IC50)，发现了2个高活性抗炎小分子先导化合物frutescone O (BFs-10)和BFs-12 (IC50: 0.36, 0.13 µM)。化合物BFs-10 (给药浓度：0.2, 0.4, 0.8 μM) 能够剂量依赖性地显著抑制促炎细胞因子IL-1β, IL-6, TNF-α的mRNA转录水平，并下调IκBα, ERK, JNK, p38 MAPK蛋白磷酸化水平。进一步通过尿酸钠诱导小鼠痛风性关节炎模型，对活性化合物BFs-12进行体内药效学评价，结果表明，BFs-12能够显著抑制巨噬细胞凋亡和IL-1β炎症因子分泌，并能够通过减轻线粒体损伤介导的氧化应激反应，干扰pro-Caspase 1和ASC的结合，及抑制 MAPK/NF-κB 信号通路阻断 NLRP3 的激活，减轻脚垫注射尿酸钠所致痛风性关节炎模型小鼠踝关节肿胀，对临床类风湿性及痛风性关节炎具有潜在的治疗价值。同时，本项目对桃金娘科药用植物番石榴进行PTP1B酶抑制活性成分研究，分离鉴定13个混源萜类化合物，其中新化合物10个psiguadiols A~J (PG-1~10)，初步揭示了番石榴降糖药效物质，为基于PTP1B酶抑制的小分子先导化合物的发现及新型降糖药物的研究开发提供科学依据。.