新型抗肿瘤二萜生物碱长链脂肪酸酯衍生物的合成、构效关系及其抗肿瘤机制研究

As the characteristic components of ranunculaceae plants, diterpenoid alkaloids present extensive biological activities. But the clinical applications are restricted due to their obvious toxicity. However, the lipo-diterpenoid alkaloids show significantly lower toxicity, and more remarkable target to tumor. In our previous study, 28 aconitine-derivatives were synthesized, and their biological studies showed that the lipo-diterpenoid alkaloids could incarese their antitumor activities. Meanwhile, two lipo-diterpenoid alkaloids(25 and 26), possing significant antitumor activities in vitro, with IC50 value comparable to doxorubicin, have been isolated from Aconitum sinchiangense W. T. Wang. And they showed no obvious toxicity to human umbilical vein endothelial cells HUVEC. It is concluded that lipo-diterpenoid alkaloids maybe used for the tumor-therapy in the future. In this project, in order to discover better tumor inhibitor, we proposed the idea of diversity-oriented synthesis for a variety of lipo-diterpenoid alkaloids from the raw material, aconitine.In addition, their structure-activity relationships, pharmacophore, and action mechanism will be explored for providing a scientific basis for looking for new antitumor agents.

二萜生物碱的明显毒性制约了相应的临床应用。然而，当其与长链脂肪酸成酯后，毒性明显降低，并能增强其对肿瘤组织的靶向性，实现增效减毒。本课题组在前期工作中，以乌头碱为原料进行多样性导向合成，制备衍生物28个，发现当长链脂肪酸酰化后能明显提高乌头碱衍生物的体外抗肿瘤活性。同时，前期从新疆乌头中分离得到两个二萜生物碱长链脂肪酸酯（25-26）具有与阿霉素相当的显著体外抗肿瘤活性，并对正常细胞呈低毒性。可见二萜生物碱长链脂肪酸酯类似物具良好的抗肿瘤增效减毒趋势，有望开辟其在抗肿瘤方面的应用。本项目拟以易得的乌头碱为原料，基于官能团多样化的设计原则，采用经典的药物合成方法系统性地合成出数量多、结构特异、取代多样、结构简化的类似物，以寻找活性更高、毒性更小、结构更简单的先导化合物，解决该类化合物天然来源不足的问题，并探讨其抗肿瘤构效关系、药效核及作用机制,为寻找新型抗肿瘤先导化合物提供科学依据。

(1) 以乌头碱、中乌碱、黄草乌甲素、高乌甲素为原料，制备了70余个类似物，对其中五十余个长链脂肪酸酯衍生物进行了乳腺癌细胞MCF-7及ADR/MCF-7的增殖抑制活性研究，其中15个化合物显示出良好的细胞毒性作用，特别其良好的抗耐药活性让人惊喜。.(2) 构效研究表明：乌头碱型C19-二萜生物碱中3-OH，8-lipo，N-CH3或N-CH2CH3均为抗肿瘤细胞增值必要条件。.(3) 分子对接结果显示，先导化合物乌头碱亚油酸脂与拓扑异构酶II对接效果最佳且对topo IIα 对接效果良好，对topo IIβ 无明显对接作用。.(4) 初步药理机制研究表明，该类化合物主要作用于细胞有丝分裂S期，在IC50下对细胞细胞膜有一定的破坏，并不能诱导MCF-7细胞发生凋亡，而可能是通过细胞自噬及坏死途径导致细胞死亡；其表现出的对TOPO Ⅱα活性明显的抑制作用，而对TOPO Ⅰ活性无影响，说明乌头碱亚油酸酯是一种TOPO Ⅱα抑制剂。(5) 通过细胞毒性试验和急性毒性试验，显示乌头碱长链脂肪酸酯衍生物比乌头碱安全性大大提高。.(6) 本研究目前取得阶段性成果：发表SCI论文3篇，授权国际专利1项，申请中国发明专利2项，培养硕士研究生3名。