相转移催化法合成喜树碱糖苷及其对Topo I抑制活性

目的寻找高效低毒的喜树碱类抗肿瘤新药。方法采用相转移催化法合成了6个喜树碱糖苷衍生物(7～12)，经¹H NMR，IR和MS分析确证了化合物的结构。采用MTT法考察了所合成的喜树碱糖苷对肿瘤细胞抑制活性，采用分子生物学手段考察了所合成的喜树碱糖苷衍生物对Topo I的抑制活性。结果和结论相转移催化法大大提高了喜树碱糖苷的合成收率，喜树碱糖苷类化合物对肿瘤细胞的体外抑制活性较喜树碱母核显著降低，但仍保持很好的Topo I抑制活性。     

相转移催化法合成喜树碱糖苷及其对Topo Ⅰ抑制活性

目的寻找高效低毒的喜树碱类抗肿瘤新药.方法采用相转移催化法合成了6个喜树碱糖苷衍生物(7～12),经1H NMR,IR和MS分析确证了化合物的结构.采用MTT法考察了所合成的喜树碱糖苷对肿瘤细胞抑制活性,采用分子生物学手段考察了所合成的喜树碱糖苷衍生物对Topo Ⅰ的抑制活性.结果和结论相转移催化法大大提高了喜树碱糖苷的合成收率,喜树碱糖苷类化合物对肿瘤细胞的体外抑制活性较喜树碱母核显著降低,但仍保持很好的Topo Ⅰ抑制活性.     

10-羟基喜树碱衍生物的合成及体外抑制肿瘤活性

目的寻找高效低毒的喜树碱类抗肿瘤新药。方法合成7个喜树碱衍生物（3~9），经¹HNMR，IR，MS分析确证了所合成化合物的结构，经MTT法筛选了对宫颈癌Hela、肝癌BEL-7402、胃癌7901和大肠癌CCL-187瘤株的体外抑制肿瘤活性。结果7个化合物分别对前三种瘤株有效，其中化合物4对前三种瘤株均有较好的体外抑制肿瘤细胞活性，尤其对宫颈癌Hela细胞的抑制活性大于10-羟基喜树碱。结论该类化合物的抗癌活性值得进一步研究。     

新型6-芳基茚并异喹啉酮衍生物的合成及抗肿瘤活性研究

目的合成一系列新型结构6-芳基茚并异喹啉酮衍生物,并考察目标化合物对DNA拓扑异构酶Ⅰ（TopoⅠ）的抑制活性及其体外抗肿瘤活性。方法以茚和间氯苯甲酸为原料,分别合成高酞酸和4-甲氧基高酞酸;高酞酸通过脱水反应、与亚胺加成反应制得中间体6-芳基茚并异喹啉酮;该中间体与各种氨基取代的氯代物反应得到目标化合物。采用TopoGEN公司的Topoisomerase Ⅰ drug screning kit来测试目标化合物对TopoⅠ的抑制活性;选取人乳腺癌细胞（MCF-7）、非小细胞肺癌细胞（NIH-H460）和人神经胶质瘤细胞（U251）对目标化合物进行体外抗肿瘤活性筛选。结果与结论共合成了17个未见文献报道的新化合物,其结构均经MS（EI）、1H-NMR确证。体外活性筛选结果表明：目标化合物对TopoⅠ表现出良好的抑制作用,且对3种肿瘤细胞表现出较好的抗增殖活性。     

7-去氮腺苷衍生物的合成及生物活性研究

目的 合成7—位炔基修饰的7—去氮腺苷衍生物，并对这些化合物的抗肿瘤活性及对细胞周期的影响进行考察。方法 在Pd(PPh3)4和CuI的催化下，5—碘—7—去氮腺苷与炔烃反应合成目标化合物，用MTT法评价化合物的抗肿瘤活性，用流氏细胞术考察化合物对细胞周期的影响。结果与结论 合成了4种7—去氮腺苷衍生物，这些化合物对肿瘤细胞的生长具有中等强度的抑制活性，化合物3a可使HL—60和KB细胞周期阻断在Gl期并使HL—60细胞产生凋亡，但对KB细胞不产生凋亡。     

喜树碱-甾体新缀合物的设计合成及抗肿瘤活性

目的:设计合成喜树碱-甾体新缀合物,考察其抗肿瘤活性。方法:以喜树碱或者7-羟甲基喜树碱和一系列甾体酸为原料,采用EDCI-DMAP偶合法,合成喜树碱-甾体新缀合物;以喜树碱为阳性对照,采用MTT法进行初步的体外抗HepG2细胞活性筛选。结果:喜树碱-甾体新缀合物的结构通过1H-NMR,质谱和元素分析确认;化合物2a,3d对HepG2细胞的抑制活性明显高于喜树碱。结论:合成的喜树碱-甾体缀合物2a,3d有较好活性,值得进一步研究。     

喜树碱结构修饰与构效关系研究进展

喜树碱是从喜树提取物中分离出的能够抗细胞增殖的天然生物碱。由于其溶解性低、稳定性差和显著的不良反应限制了其临床应用,所以在过去的十余年里合成了许多喜树碱衍生物。通过引入极性基团、靶向剂或药效团拼合、前药等在喹啉环、5位和20位进行结构修饰,其中大多数与喜树碱相比显示出更强的效力,对不同的肿瘤细胞具有活性,其中许多对多药耐药肿瘤细胞具有活性。综述了近年来47个新的喜树碱衍生物的合成方法和生物活性,并总结了构效关系,发现在喹啉环和内酯环的羟基上修饰通常可以增强体外抗肿瘤活性,药物递送系统、计算机高通量筛选等新技术的应用为改善喜树碱的溶解性、稳定性,寻找活性较好的先导化合物拓展了新思路。     

α-硫辛酸衍生物的合成及其抗癌活性研究

目的设计合成α-硫辛酸衍生物,并测定其体外对肿瘤细胞的抑制活性。方法首先,以邻硝基氟苯为起始原料,经亲电取代和氧化反应合成抗肿瘤药替拉扎明,同时以色氨酸为起始物合成L-色氨酸甲酯盐酸盐;然后将替拉扎明和色氨酸甲酯盐酸盐分别与外消旋的或光学纯的硫辛酸进行酰胺缩合制得目标化合物。采用MTT法考察目标化合物对肿瘤细胞株ES-2、K562、PC-3、MDA-MB-231和A549的体外抑瘤活性。结果与结论合成了4个未见文献报道的新硫辛酸衍生物,其结构经1H-NMR、MS谱确证。目标化合物对实验的肿瘤细胞均具有一定的抑制活性,其中,化合物Ⅱ的活性最好,其IC50值在10μmol·L-1以内。     

去氢骆驼蓬碱衍生物的合成和抗肿瘤活性研究

目的合成去氢骆驼蓬碱衍生物并研究其抗肿瘤活性。方法以去氢骆驼蓬碱为原料,在NaH催化下先用卤代烷烃对9位氮原子进行烷基化,然后用溴化苄将2位氮原子进行季铵化,得到一系列去氢骆驼蓬碱衍生物,用MTT法考察其对肿瘤细胞的抑制作用。结果合成了6个新的去氢骆驼蓬碱衍生物,结构经1H-NMR、MS和红外光谱确证。与去氢骆驼蓬碱相比,所合成的化合物均有明显的抗肿瘤活性。结论初步药理实验结果表明去氢骆驼蓬碱9-苯丙基取代能够明显提高抗肿瘤效果。     

咔啉类衍生物的合成及抗肿瘤活性研究

目的合成咔啉类衍生物并研究其抗肿瘤活性。方法以α-咔啉、β-咔啉以及1,2,3,4-四氢-β-咔啉-3-羧酸为原料,经过多步反应分别得到6-取代α-咔啉类、6-取代β-咔啉类以及3-取代β-咔啉类衍生物,用MTT法考察目标化合物对肿瘤细胞的抑制作用。结果合成了15个新的咔啉类衍生物,结构经过1H NMR和ESI-M S确证。结论 MTT法测试所得的目标化合物对2种受试细胞株均具有一定的抗肿瘤活性,部分化合物显示出与阳性对照紫杉醇相当或更佳的肿瘤细胞抑制活性。     

Design,synthesis, and docking study of new quinoline derivatives as antitumor agents

New quinolines substituted with various heterocycles and chalcone moieties were synthesized and evaluated as antitumor agents. All the synthesized compounds were in vitro screened against 60 human cancer cell lines. Compound 13 showed the highest cytotoxicity toward 58 cell lines, exhibiting distinct growth inhibition values (GI₅₀) against the majority of them, including SR, HL‐60 (TB) strains (leukemia), and MDA‐MB‐435 strains (melanoma), with GI₅₀ values of 0.232, 0.260, and 0.300 µM, respectively. It exhibited great selectivity toward cancer cell lines, with less toxic effect against normal cells represented by skin fibroblast (BJ) and breast epithelial cell lines (MCF‐10F). The enzyme inhibitory activity of compound 13 was evaluated against topoisomerase 1 (Topo 1), epidermal growth factor receptor and vascular endothelial growth factor receptor 2, where it displayed worthy Topo 1 inhibition activity with an IC₅₀ value of 0.278 µM compared with camptothecin as a reference drug (IC₅₀ 0.224 µM). Docking studies were performed to investigate the recognition profile of compound 13 with the Topo 1 enzyme binding site.     

Synthesis and bioevaluation of diphyllin glycosides as novel anticancer agents

A series of diphyllin glycosides were synthesized from diphyllin by phase transfer catalysis glycosylation, deprotection, and etherification, and the structures were established by (1) H NMR, (13) C NMR, and HRMS. These glycosides were evaluated for their in vitro cytotoxicity against HCT-116, A549, and A549T cancer cell lines by MTT assay, and most of them were cytotoxic at submicromolar concentrations. They were also effective against the paclitaxel-resistant cell line A549T. The kDNA decatenation assay indicated that most of these compounds inhibited topoisomerase IIα-mediated kDNA decatenation. In addition, the in vitro tubulin polymerization study showed that compounds 5 and 6 had antimicrotubule activity with a paclitaxel-like mode of action. Taken together, these results suggest that these diphyllin glycosides act on both TopoII and tubulin.     

Synthesis and biological evaluation of novel A-ring modified hexacyclic camptothecin analogues

Eleven A-ring modified hexacyclic analogues of camptothecin (CPT) containing a 1,4-oxazine ring were synthesized from 10-hydroxycamptothecin (11a) and 7-ethyl-10-hydroxycamptothecin (3) (SN-38) in four to five steps and were subjected to the biological tests such as cytotoxicity, topoisomerase I (Topo I) inhibitory activity, acetylcholinesterase (AChE) inhibition, and stability in human plasma. Four compounds 15a, 15b, 16a, and 16c were about 2-fold more potent than topotecan and as potent as CPT toward human cancer cell lines A549, H128, WiDr, MKN45, SK-OV-3, and SK-BR-3 in vitro, even though the most active compound 15b was slightly less potent than SN-38. The potency of Topo I inhibition of these compounds showed relatively good correlation with their cytotoxicity. Most of the compounds exhibited AChE inhibitory activity weaker (9 +/- 2 to 20 +/- 3%) than CPT (23 +/- 5%) or topotecan (20 +/- 4%) and similar to SN-38 (13 +/- 2%), indicating that they might have little effect on causing early diarrhea. The stability of lactone forms of these compounds in human plasma seemed to be much higher than that of CPT and similar to that of topotecan but lower than that of SN-38. Among the new hexacyclic CPT analogues, compound 15b showed higher antitumor activity against human tumor xenograft, WiDr, in nude mice compared to that of SN-38. The most promising compound 15b has been selected for further development.     

Transport mechanism-based drug molecular design: novel camptothecin analogues to circumvent ABCG2-associated drug resistance of human tumor cells

Acquired and intrinsic drug resistance in cancer is the major obstacle to long-term, sustained patient response to chemotherapy. Irinotecan (CPT-11) is a widely-used potent antitumor drug that inhibits mammalian DNA topoisomerase I (Topo I). However, overexpression of ABCG2 (BCRP/MXR/ABCP) reportedly confers cancer cells resistance to SN-38, the active form of CPT-11. To circumvent the ABCG2-associated drug resistance, we have synthesized and characterized a total of fourteen new camptothecin (CPT) analogues with respect to both the inhibition of Topo I and the substrate specificity of ABCG2. While the lactone E ring is a prerequisite for anticancer activity, modifications of the A or B rings do not significantly affect Topo I inhibition activity. In this context, we have synthesized new CPT analogues with different substitutions at positions 10 or 11 of the A ring. All of the tested CPT analogues strongly inhibited the Topo I activity in a cell-free system. Accordingly, we have examined ATP-dependent transport of those CPT analogues by using plasma membrane vesicles prepared from ABCG2-overexpressing cells. Based on the substrate specificity of ABCG2 thus evaluated, it is strongly suggested that CPT analogues with a hydroxyl group at position 10 or 11 of the A ring are good substrates for ABCG2 and therefore effectively extruded from cancer cells. Thus, hydrogen bond formation is considered to be involved in substrate recognition and/or transport processes of ABCG2. The present study provides a practical approach to discover new CPT-based drugs for the chemotherapy of drug-resistant human cancer.     

Synthesis and antitumor characterization of pyrazolic analogues of the marine pyrroloquinoline alkaloids: wakayin and tsitsikammamines

A series of aza analogues of the marine alkaloids wakayin and tsitsikammamines A and B have been synthesized. The strategy used was based on [3 + 2] cycloaddition reactions involving 3-ethylamine-indole-4,7-dione and different diazo reagents. All the compounds were evaluated in vitro for antiproliferative activity against five distinct cancer cell lines and for their inhibitory effect on topoisomerase isoenzymes I and II. Some of the compounds inhibited the topoisomerase I and/or II catalyzed relaxation of supercoiled DNA at a concentration comparable to the drugs camptothecin and etoposide. Only a few of them exhibited cytotoxic activity with IC50 values in the micromolar range.     

Topoisomerase I-mediated antiproliferative activity of enantiomerically pure fluorinated homocamptothecins

Homocamptothecin (hCPT) is an E-ring modified camptothecin (CPT) analogue bearing a methylene spacer between the alcohol and carboxyl functions of the CPT lactone. Combining pronounced inhibitory activity of topoisomerase I (Topo I) with enhanced plasma stability, hCPT constitutes an attractive template for the elaboration of new anticancer agents. Fluorinated hCPT analogues, prepared in enantiomerically pure form, were assayed by their stimulation of Topo I-mediated DNA cleavage. Translation into cytotoxicity against tumor cells was evaluated on HT29 human colon adenocarcinoma and on the multidrug resistant lung and bladder tumor cell lines, A549 and T24r. Good correlation is observed between the ability of the drugs to stimulate Topo I-mediated DNA cleavage and the respective 50% inhibitory concentrations (IC(50) values) of the HT29, A549, and T24r cell growth. Fluorine substitution in the A-ring of hCPT was found to have a pronounced influence on biological activity, providing several compounds which are up to 100-fold more potent than CPT in terms of IC(50). Among these, 10,11-difluoro-hCPT has been selected for further development.     

Inhibition of eukaryotic DNA topoisomerase I and II activities by indoloquinolinedione derivatives.

With the aim of obtaining new inhibitors of topoisomerases, we have evaluated various heterocyclic quinone derivatives for their ability to induce topoisomerase I (Topo I)- or Topo II-associated DNA breaks, using P388 cell nuclear extract. Several compounds belonging to the indolo[3,2-c]quinoline-1,4-dione series have been shown to possess DNA-cleavage activity. Further analysis using purified Topo I and II preparations has indicated that the members of the series stimulate cleavable complex formation of both Topo I and II. 3-Methoxy-11H-pyrido[3',4':4,5]pyrrolo[3,2-c] quinoline-1,4-dione (AzalQD), one of the most active members of the series, stimulates cleavable complex formation and inhibits the catalytic activities of both eukaryotic Topo I and II, with, however, less potency than camptothecin and etoposide. Topo I cleavage site patterns for AzalQD and camptothecin were found to be nearly identical, with, however, some differences in cleavage site intensities. Use of filter binding assays also indicates that AzalQD is at least 10 times more potent against Topo I than against Topo II. Structure-activity relationships of indoloquinolinedione derivatives have been established and have shown that Topo I and II inhibitions are strongly linked, with a dose-selective preference towards Topo I. AzalQD does not display detectable DNA-unwinding properties. AzalQD induces a preferential cytotoxicity for the yeast strain JN2-134 bearing the human top1 gene under the control fo the GAL1 promoter, indicating that Topo I inhibition is responsible for the yeast cytotoxicity. These data indicate that AzalQD and its structural analogs represent a new distinct class of eukaryotic Topo I and II inhibitors.     

Antitumor triptycene bisquinones: a novel synthetic class of dual inhibitors of DNA topoisomerase I and II activities

Synthetic triptycene analogs (TT code number) mimic the antitumor effects of daunorubicin in the nanomolar range in vitro, but have the advantage of blocking nucleoside transport and retaining their efficacy in multidrug-resistant (MDR) tumor cells. Since TT bisquinones induce poly(ADP-ribose) polymerase-1 cleavage at 6 h and internucleosomal DNA fragmentation at 24 h, which are, respectively, early and late markers of apoptosis, these lead antitumor drugs were tested for their ability to trigger the DNA topoisomerase (Topo) inhibitions responsible for the initial and massive high-molecular-weight cleavage of DNA required for tumor cells to commit apoptosis. Interestingly, antitumor TTs have the unusual ability to inhibit, in a concentration-dependent manner, the relaxation of supercoiled plasmid DNA catalyzed by both purified human Topo I and II enzymes. However, if there is a relationship between the ability of TT analogs to inhibit Topo activities and their quinone functionality and cytotoxicity, it is far from perfect, suggesting that other molecular targets may be involved in the mechanism of action of these antitumor drugs. Moreover, one of the most cytotoxic TT bisquinone, 6-bromo-7-methoxy- or 7-bromo-6-methoxy-2-N-methylamino-1 H,4 H,5 H,8H-9,10-dihydro-9,10-[1',2']benzenoanthracene-1,4,5,8-tetraone (TT24), inhibits Topo II activity more effectively than amsacrine (m-AMSA) and matches the Topo I inhibitory effect of camptothecin (CPT). The dual inhibitory activity of TT24 is substantiated by the findings that TT24 mimics the action of m-AMSA in the Topo II assay, where the Topo I inhibitor CPT is ineffective, and also mimics the action of CPT in the Topo I assay, where the Topo II inhibitor etoposide is ineffective. Because of their ability to target nucleoside transport and topoisomerase activities, synthetic TT bisquinones might represent a novel class of bifunctional drugs valuable to develop new means of polychemotherapy and circumvent MDR.