截叶铁扫帚抗溃疡性结肠炎活性成分及其作用机制研究

Ulcerative colitis (UC), as one category of inflammatory bowel disease, is a chronic inflammation disease of non-specific. In recent years, the incidence of UC is increasing rapidly in our country. UC is rated by the world health organization as one of the modern diseases, which is difficult to be cured. Balance between inflammatory cytokines and anti-inflammatory cytokines play an important role in the formation and development of UC. Therefore, only by inhibiting the activation of inflammatory cytokines, and further suppressing the occurrence and development of inflammation is the key to the treatment of UC. However, the defect of western medicine such as recur easily, toxical and side effects were seldom found in using Traditional Chinese medicine (TCM). TCM is an important source of anti-ulcerative colitis drug. In the previous research, we investigated a 70% EtOH extract of the aerial parts of Lespedeza cuneata, and identified 8 lignan glucosides. In in vitro bioassays, some lignan glucosides (1, 3, 4, 6, and 8) had a certain transcriptional activation effect on UC. As part of our continuing search for functional substances from L. cuneata, we are plan to further enrich, separate and identify these lignan compounds with guidance of bioactivities screening, and study their anti-ulcerative colitis ingredients’s mechanism via TLRs/NF-κB. In summary, we hope to provide useful information for the reasonable application of L. cuneata. This research may be beneficial to the development of independent intellectual property rights of anti-ulcerative colitis drug.

溃疡性结肠炎（UC）是一种常见的肠道慢性非特异性炎症性疾病，近年来发病率持续升高，被世界卫生组织列为现代难治病之一。炎症因子的表达平衡失调所致的免疫异常被视为是UC的重要发病机制，用药物抑制炎症相关因子活化，进而抑制炎症的发生及发展，是UC治疗的关键。目前治疗UC的药物普遍存在严重的不良反应，而中药疗效确切、毒副作用小，是UC药物的重要来源。前期，我们从截叶铁扫帚中分离得到的大部分木脂素类化合物显示具有一定的体外抗UC活性。本研究计划通过体外抗UC活性追踪，运用各种现代色谱分析分离技术，继续富集截叶铁扫帚中的抗UC活性成分，以期获得结构新颖的先导化合物，研究其对TLRs/NF-κB信号通路相关的多种炎症因子的表达影响，进一步阐明截叶铁扫帚抗溃疡性结肠炎的药效物质基础。本研究的顺利实施可为截叶铁扫帚的合理开发提供科学依据，为研发具有知识产权的UC新药奠定良好的前期基础。

本项目以中医药理论为指导，运用现代科学技术与方法，以抗溃疡性结肠炎活性为导向，对豆科胡枝子属植物截叶铁扫帚Lespedeza cuneata (Dum.Cour.) G.Don的化学成分及其活性进行了系统的研究。应用HPLC-MS/MS、HPLC及其他现代色谱技术从截叶铁扫帚植物中分离了95个化合物，其中木脂素类化合物25个、酚酸类化合物15个、萜类化合物16个、黄酮类化合物24个，其他化合物15个，并采用波谱和化学方法鉴定这些化合物的结构。在分离并鉴定的化合物中，21−30为新化合物，其他化合物大多为首次从该植物中分离得到。本项目选用先进的靶向xbp1双荧光素酶报告基因体外抗溃疡性结肠炎活性评价模型，对分离得到的主要化学成分进行抗溃疡性结肠炎活性筛选，共有16个木脂素类化合物显示对大鼠小肠隐窝上皮细胞(IEC-6)中xbp1基因的表达具有转录激活效应，具有一定的体外抗溃疡性结肠炎活性。综合前期活性筛选结果，采用三硝基苯磺酸诱导的小鼠溃疡性结肠炎模型，对其中一个活性显著、含量丰富的新化合物(−)-(8S,7′R,8′S)-isolariciresinol-9′-O-α-L-rhamnoside (3)进行了体内活性研究。研究发现，化合物3各剂量可以不同程度地减轻UC小鼠结肠组织损伤程度，降低UC小鼠结肠指数和脾脏指数，提高胸腺指数；显著降低小鼠结肠组织中TNF-α、IL-lβ和IL-6的水平，并抑制NF-κB/TLR4信号通路的传导。研究结果进一步确定截叶铁扫帚植物中木脂素类化合物是抗溃疡性结肠炎活性的主要有效成分，从分子和整体动物水平阐明了截叶铁扫帚抗溃疡性结肠炎的物质基础，为该植物的资源开发和合理应用提供系统的科学资料，为抗溃疡性结肠炎新药的研制奠定了基础。