线粒体靶向的两种五环三萜衍生物的合成与选择性抗肿瘤活性研究

发布时间：2018-05-20 23:46

本文选题：抗肿瘤 + 线粒体靶向　；参考：《山东大学》2017年硕士论文

【摘要】：白桦醇(Betulin,BN)和白桦酸(Betulinic acid,BA)是植物中常见的两种五环三萜,具有广泛的药理活性,特别是抗肿瘤活性。目前有研究对这两种化合物的结构进行了改造,增加了它们的抗肿瘤活性。但是水溶性差、生物利用度低,选择性差等依然是其应用于临床需要解决的问题。对肿瘤细胞的深入研究表明,程序性凋亡系统发生障碍是其可以无限复制而逃避自然凋亡的主要原因,而线粒体在细胞的凋亡中发挥着重要的作用。与正常细胞相比,肿瘤细胞线粒体的结构和功能都发生了不同程度的变化,其中之一就是线粒体膜电位明显高于正常细胞,利用这一特点可将化疗药特异性靶向至肿瘤细胞的线粒体,调节其功能,从而选择性诱导肿瘤细胞的凋亡。常用的靶向方法是采用电子移位亲脂性阳离子(Delocalized Lipophilic Cations,DLCs)作为线粒体靶向载体,如三苯基膦盐(TPP+)。目前已有多种抗肿瘤化合物与TPP+连接后大幅提高了其抗肿瘤活性或改善了肿瘤的抗药性。本文以BN和BA为原料,设计并合成了六个TPP+衍生物,以期将这两种三萜化合物靶向至线粒体,提高其抗肿瘤活性和选择性。抗肿瘤活性与作用机制研究显示所有连接有TPP+的化合物与母药相比抗肿瘤活性均有了大幅度的提高,而且选择性有一定改善。其中Mito-BA-1和Mito-BN-1的活性最好。进一步实验结果表明,Mito-BN-1在K562细胞线粒体中的累积约是母药BN的三倍,证明其具有了线粒体靶向作用。研究表明Mito-BA-1和Mito-BN-1的抗肿瘤机制包括增加细胞内ROS的产出,降低线粒体膜电位,促进凋亡蛋白Cytochrome c自线粒体向细胞质的释放,以及Caspase家族蛋白的活化,最终诱发肿瘤细胞的凋亡。此外,Mito-BN-1在K562细胞的斑马鱼移植瘤模型中有抑制癌细胞的增殖与迁移的作用,有效作用浓度低至BN的1/20。本研究所用合成步骤简单,所需要的试剂相对廉价,易于放大生产,而细胞与动物体内实验证实了所设计线粒体靶向衍生物的有效性,为五环三萜类化合物的抗肿瘤应用提供了思路。
[Abstract]:Bai Hua (BN) and Bai Hua (Betulinic acid) are two common triterpenoids in plants, which have a wide range of pharmacological activities, especially antitumor activities. Current studies have modified the structures of these two compounds to increase their anti-tumor activity. However, poor water solubility, low bioavailability and poor selectivity are still the problems to be solved in clinical application. The further study of tumor cells shows that the main reason why the programmed apoptosis system is blocked is that it can replicate infinitely and escape from natural apoptosis. Mitochondria play an important role in the apoptosis of tumor cells. Compared with normal cells, the structure and function of mitochondria in tumor cells changed in varying degrees, one of which was that the membrane potential of mitochondria was significantly higher than that of normal cells. Using this characteristic, the chemotherapeutic drugs can be specifically targeted to the mitochondria of tumor cells and regulate their function, thus selectively inducing apoptosis of tumor cells. The commonly used targeting method is to use electron translocation lipophilic cationic Lipophilic cations (DLCs) as mitochondrial targeting carriers, such as triphenylphosphine salt (TPS). At present, many antitumor compounds have been linked with TPP to improve their antitumor activity or drug resistance. In this paper, six TPP derivatives were designed and synthesized from BN and BA in order to target the two triterpenoids to mitochondria and improve their antitumor activity and selectivity. The study of antitumor activity and action mechanism showed that all the compounds with TPP were significantly improved in antitumor activity compared with the mother drug and the selectivity was improved to a certain extent. Among them, Mito-BA-1 and Mito-BN-1 have the best activity. The further results showed that the accumulation of Mito-BN-1 in mitochondria of K562 cells was about three times as much as that of BN, which proved that Mito-BN-1 had mitochondrial targeting effect. The antitumor mechanisms of Mito-BA-1 and Mito-BN-1 include increasing the production of ROS, decreasing mitochondrial membrane potential, promoting the release of apoptotic protein Cytochrome c from mitochondria to cytoplasm, and activating Caspase family proteins, which can induce apoptosis of tumor cells. In addition, Mito-BN-1 can inhibit the proliferation and migration of cancer cells in the transplanted tumor model of zebrafish in K562 cells. The effective concentration of Mito-BN-1 is as low as 1 / 20 of BN. The synthetic steps used in this study are simple, the reagents needed are relatively cheap and easy to be amplified in production. Experiments in vivo with cells and animals have proved the effectiveness of the designed mitochondrial targeting derivatives. It provides an idea for antitumor application of pentacyclic triterpenoids.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R914;R96

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