蓝桉叶中DNA拓扑异构酶Ⅰ催化型抑制剂的发现及抗肿瘤活性研究

The discovery of antitumor drug with new mechanism of action or new structure is important to overcome drug resistance. DNA topoisomerase Ⅰ(Top1) is a validated target for antitumor agent, several inhibitors have been approved for clinical treatment of tumor. These inhibitors belong to Top1 poison, which can stabilize Top1-DNA covalent cleavage complex (Top1cc). In clinical practice, the Top1 poison led to serious drug resistance. Unlike Top1 poison, the Top1 catalytic inhibitors can prevent the formation of the Top1cc by blocking the nucleophilic attack of the scissile strand. The Top1 catalytic inhibitors are a kind of Top1 specific inhibitors with new mechanism of action. In a previous study, use bioassay–guided isolation of Top1 inhibitors from an active fraction of the leaves of Eucalyptus globules Labill, isolation and identification of new structure of meroterpenoids. Form the cytotoxicity test, the result show meroterpenoids notable anticancer activity. Further studies revealed that meroterpenoids are a class of Top1 catalytic inhibitors. It shows constituents from the leaves of Eucalyptus globules Labill, with novel structure and new mechanism of action. In this project, we design: 1) to obtain more novel structures, higher activity leading compounds from other active fraction of the leaves of Eucalyptus globules Labill; 2) to study the Top1 inhibitory activity and the inhibition mechanism for leading compound; 3) to discuss the relationship with Top1 inhibitory activity and anticancer activity. This study will set up a basis for the discovery of the new mechanism of action and new structure of potential plant source of antitumor agent.

发现新作用机制或新结构的药物是克服肿瘤耐药的重要手段。DNA拓扑异构酶Ⅰ（Top1）是可信的抗肿瘤治疗靶点，已有多个抑制剂应用于临床。这些抑制剂可稳定Top1-DNA共价复合物（Top1cc），属于Top1毒剂，但在临床使用中产生了严重的耐药性。Top1催化型抑制剂作用于Top1cc形成的上游阶段，是一类新作用机制的抑制剂。前期研究中，我们以Top1抑制活性为导向从蓝桉叶的一个活性馏分中，分离获得了一类具有新颖结构的杂萜类化合物。系统研究证实，它们是一类Top1催化型抑制剂，并表现出显著的抗肿瘤活性。这表明，蓝桉叶中含有新结构、新作用机制的抗肿瘤活性分子。基于此，我们计划系统研究蓝桉叶的其它活性馏分，以期发现更多新结构的高活性Top1催化型抑制剂；深入研究其Top1抑制活性及作用机制；探讨其Top1抑制活性与抗肿瘤活性之间的关联性，为发现天然来源的新机制、新结构的抗肿瘤药物奠定基础。

发现新作用机制或新结构的药物是克服肿瘤耐药的重要手段。DNA拓扑异构酶Ⅰ (Top1) 是可信的抗肿瘤治疗靶点，已有多个抑制剂应用于临床。这些抑制剂可稳定Top1-DNA共价复合物 (Top1cc)，属于Top1毒剂，但在临床使用中产生了严重的耐药性。Top1催化型抑制剂作用于Top1cc形成的上游阶段，是一类新作用机制的抑制剂。本项目以Top1抑制活性为导向从蓝桉中分离、纯化并鉴定了20个间苯三酚杂萜类化合物，其中有10个化合物为新化合物，命名为eucalypglobulusals A-J (1-10)。通过Top1抑制活性和细胞毒实验，验证单体化合物的活性。结合化合物结构式新颖性分析确定以化合物1和13为代表进行深入的作用机制研究。通过化合物与Top1的作用模式研究。确定这类化合物为Top1催化型抑制剂，具有显著的抗肿瘤活性。本项目丰富了桃金娘科植物中间苯三酚杂萜类化合物的结构类型。阐明了间苯三酚杂萜类化合物的Top1抑制活性及其作用机制。为发现天然来源的新机制、新结构的抗肿瘤药物奠定基础。.综上，经过三年的努力，已完成课题的预定目标，共发表SCI论文7篇。

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