【作者】 王军飞；

【导师】 李英霞；

【作者基本信息】 中国海洋大学 ， 药物化学， 2011， 博士

【摘要】 恶性肿瘤是严重威胁人类生命和生活质量的主要疾病。近几十年来,人们相继发现了许多高细胞毒类化疗药物在临床上作为一线用药应用于多种癌症的治疗。然而,长期的化疗给药导致的多药耐药限制了对癌症病人的成功治疗。多药耐药主要归因于P-糖蛋白(P-gp)在肿瘤细胞中过表达,P-gp外排泵能够显著降低细胞内化疗药物的浓度。例如明星分子紫杉醇(泰素)和多西紫杉醇(多西他赛)尽管具有广谱显著的抗肿瘤作用,然而对P-糖蛋白(P-gp)过表达的多药耐药肿瘤几乎没有抑制活性,主要归因于其均为P-gp良好的底物。因此,紫杉醇的研发趋势转向于:发展具有更好的药理学性质并提高对各种肿瘤的治疗指数,尤其是针对多药耐药肿瘤的新一代紫杉烷类抗肿瘤药。传统中药被认为是抗肿瘤药物新的来源,它们可以作为临床化疗的辅助用药来增强化疗效果并降低化疗过程中的毒副作用。黄芩素是一种生物活性黄酮类化合物,它在中国和其它历史悠久的国家被广泛用来治疗各种疾病。虽然黄芩素抗肿瘤活性比其它的高细胞毒类化疗药相比要低,然而它是一种很好的P-gp的抑制剂,且对正常组织毒副作用极低。因此,大量的研究转向于开发具有更好的抗肿瘤活性的黄芩素衍生物。一、大规模高效地制备合成原料药LarotaxelLarotaxel (XRP9881)是一种骨架结构新颖的紫杉烷类衍生物,临床前研究其对紫杉烷耐药的乳腺癌肿瘤具有具有很好的抑制活性,目前已结束Ⅲ期临床研究。除此之外,由于Larotaxel可以降低与P-糖蛋白的结合,因而其可以顺利的穿越血脑屏障(BBB)。本论文以去乙酰巴卡亭Ⅲ和其它廉价易得的试剂为起始原料制备合成Larotaxel,发展了一条高效实用的制备工艺应用于其大规模的制备。我们将外消旋的β-内酰胺侧链合成工艺进行优化改进并应用于大规模制备合成Larotaxel的C-13位侧链,并发现外消旋β-内酰胺侧链C-3位的硅醚保护基对其与母核对接反应的非对映选择性有重要影响。研究发现叔丁基二甲基硅基(TBS)保护基比三异丙基硅基(TIPS)及叔丁基二苯基硅基(TBDPS)具有更好的立体选择性。该合成工艺共包含了11步反应,其中8步反应无需进一步纯化,大大缩短了投料周期。中试放大试验表明该制备工艺成本较低,收率较高且操作易控等特点。二、抗多药耐药肿瘤的新一代紫杉烷类似物的设计及合成研究本论文以拉洛他赛(Larotaxel, XRP9881)为先导化合物,对其C2,C10及C3′位点进行系统的结构修饰,共设计合成了23个新一代紫杉烷类似物,并测试了对人口腔鳞癌肿瘤细胞株KB,人乳腺癌肿瘤细胞株MCF-7以及其相关的P-糖蛋白过表达的多药耐药肿瘤细胞株KB/VCR、MCF-7/ADR的抑制活性,且对其初步的构效关系研究进行了总结。研究结果发现合成的许多紫杉烷类似物与Larotaxel(XRP9881)和Cabazitaxel (XRP6258)相比均有相对较低的耐药因子。本论文也设计合成了多个氟取代紫杉烷类似物,其中二氟取代类似物对多药耐药肿瘤细胞具有更好的抑制活性。化合物LTX-104、LTX-106、LTX-118对两株多药耐药肿瘤细胞株的抑制活性显著强于Larotaxel及Cabazitaxel,尤其是针对MCF-7/ADR的抑制活性与紫杉醇相比提高了约4个数量级,比多西他赛提高了约2个数量级。三、基于黄芩素A环修饰的抗肿瘤衍生物的设计及合成研究本文共设计合成了系列基于黄芩素A环修饰的衍生物,并测试了其对KB、KB/VCR、MCF-7及MCF-7/ADR四株肿瘤细胞株的抑制活性。研究结果发现:对黄芩素5-OH进行结构修饰对其细胞毒活性影响不大;对6-OH进行适当的酰基化可同时增强对两株敏感和两株多药耐药细胞株的抑制活性,若同时对7-OH进行结构修饰对其抑制影响较大,然而对6-OH进行烷基化修饰大多会导致活性的显著降低或丧失。对7-OH进行合适的烷基化取代修饰可增强其抗肿瘤活性。其中,化合物HQS-5、HQS-17、HQS-24对所选的四种肿瘤细胞株的抑制活性强于黄芩素,尤其是对两株耐药株KB/VCR及MCF-7/ADR具有比黄芩素更强的抑制活性。另外,该活性化合物对敏感和耐药细胞株的细胞毒活性无差异,因而它们不是P-糖蛋白的作用底物。通过对黄芩素A环进行的初步的构效关系研究,有助于我们设计活性更好的黄芩素活性分子作为临床化疗的辅助用药。更多还原

【Abstract】 Cancer is a class of diseases which endanger human life and quality of life. For several decades, many high cytotoxic agents have been applied to the first-line treatments for a wide variety of cancers in cancer chemotherapy. However, multidrug resistance (MDR) limited the success of therapy in patients treated long-term with chemotherapeutic drugs. The drug resistance is mainly due to the overexpression of the P-glycoprotein (Pgp) which is known to cause subtherapeutic intracellular drug concentrations. For example, although the famous paclitaxel (Taxol) and docetaxel (Taxotere) possessed highly potent antitumor activity, it exhibited low or no cytotoxicities against some drug-resistant (P-gp+) cells due to it acted as a good substrate of P-gp protein. Therefore, the research and development trend of paclitaxel is to develop new taxane anticancer agents with improved activity against various classes of tumors, especially against drug-resistant human cancer.Traditional Chinese medicines have been recognized as a new source of anticancer drugs and new chemotherapy adjuvant to enhance the efficacy of chemotherapy and to reduce the side effects of cancer chemotherapies. Baicalein, as a bioactive flavonoid, is one of the most popular used to treat many diseases in China and in several oriental countries. Its anti-tumor effects were weaker than other high cytotoxic agents, but it acted as a good inhibitor of P-gp and showed low toxicity toward normal tissues. Therefore, much investigations have been focused on researching and developing baicalein derivatives with better anti-tumor activities. Study on the Efficient and Large-scale Preparation of LarotaxelLarotaxel (XRP-9881) is a novel taxane derivative with preclinical activity against taxane-resistant breast cancer and has been finished in phaseⅢnow. In addition, it can also penetrate the blood brain barrier (BBB) which may also be a consequence of its decreased recognition by the P-gp.In this paper, we have developed an efficient and practical method for the large-scale preparation of larotaxel from deacetylbaccatinⅢand other cheap and readily starting materials. We improved and applied the racemic "β-Lactam Synthon Method" to the large scaled synthesis of the C-13 side chain of larotaxel. It was found that the size of the silyl protecting groups at the 3-hydroxy moiety ofβ-lactams had an important influence on the diastereoselectivity of the resolution. The tert-butyldimethylsilyl protecting group provided optimum kinetic resolution in comparison with the the larger tri-isopropylsilyl and tert-butyldiphenylsilyl group in the reactions investigated. The synthesis technology contains a total of 11-step reaction, and 8-step reaction without further purification among them, which greatly reduced the production cycle. The new synthetic method was verified by amplifying and was indicated that the process is low-cost, high-yield and controllable and so on. Study on the Design and Synthesis of Novel Anti-MDR-tumour Taxoid AnaloguesIn this paper, 23 new generation taxoids with systematic and strategic modifications at the C2, C10, and C3′positions of larotaxel were designed, synthesized, and examined for their inhibitory activities against the growth of a human oral squamous epithelium cancer cell line KB, a human breast cancer cell line MCF-7 and their P-gp 170 protein overexpressing cell lines KB/VCR, MCF-7/ADR. Their preliminary structure-activity relationships have been concluded. As a result, many of these taxoids exhibited exhibited relatively low resistance factors than larotaxel (XRP9881) and cabazitaxel (XRP6258). Many fluorinecontaining taxoids were also designed and investigated. Among them, 3′-difluorovinyl-taxoids were found to exhibit exceptionally high potency against multidrug-resistant cancer cell lines. Compounds LTX-104、LTX-106、LTX-118 exhibited much higher activity than larotaxel and cabazitaxel against multidrug-resistant cancer cell lines KB/VCR and MCF-7/ADR. They also respectively possess about two to four orders of magnitude higher potency than paclitaxel and docetaxel against drug-resistant cancer cell line MCF-7/ADR.Study on the Design and Synthesis of A-ring Modified Anti-tumour Baicalein DerivativesA series of baicalein derivatives modified on the A–ring were synthesized and screened for their inhibitory activities against the growth of KB、MCF-7 and their P-gp 170 protein overexpressing cell lines KB/VCR, MCF-7/ADR. The results indicated that modifications on 5-hydroxyl group may be not very important for their anticancer activities. Acylations of 6-hydroxyl group exhibited similar or better activities against both drug-sensitive and drug-resistant cell lines, which depended on the substitutions of 7-hydroxyl group. However, alkylations of 6-hydroxyl group generally resulted in reduced or completely loss of activities. The appropriate alkylations of 7-hydroxyl position may be favorable for the bioactivities. Among them, compounds HQS-5、HQS-17、HQS-24 exhibited higher inhibitory activities than baicalein against all the four cell lines, especially against drug-resistant cancer cells. Furthermore, the growth inhibitory IC50 of the active compounds against both drug-sensitive and drug-sensitive cancer cells are about the same, indicating that these compounds are unlikely to be the substrates of P-gp 170 protein. The preliminary SAR of baicalein on the A–ring will be favor in designing better baicalein derivatives acted as a chemotherapy adjuvant to enhance the efficacy of cancer therapeutics.更多还原