埃坡霉素高产菌株的选育及发酵培养基的优化

以埃坡霉素产生菌粘细菌纤维堆囊菌为出发菌株,经亚硝基胍诱变处理后,在含有前体丙酸盐的平板中筛选抗性突变株,得到一株高产突变株N-19,埃坡霉素产量为18.5 mg/L,比出发菌株提高了69.7.通过优化发酵培养基的碳、氮源组成,埃坡霉素产量达36.1 mg/L,此时埃坡霉素B和埃坡霉素A的比值为0.4:在摇瓶发酵过程中补加前体丙酸盐,埃坡霉素B和埃坡霉素A的比值增至2.1.     

埃坡霉素衍生物在乳癌治疗中的临床应用进展

<正>埃坡霉素(epothilone)与紫杉类一样,都是作用于细胞微管的药物。埃坡霉素家族包括16个成员,由大环内酯构成,1992年由Holf和Reichenbach从粘杆菌的发酵肉汤中分离出来。Bollag等首先报道了埃坡霉素潜在的抗肿瘤作用。埃坡霉素A和B具有相     

埃博霉素的生物合成

埃博霉素是由黏细菌纤维堆囊菌产生的次级代谢产物。与紫杉醇相似,它们可以抑制微管解聚,使细胞有丝分裂终止在G2-M期。在P-糖蛋白表达型的多药耐药性肿瘤细胞系中维持很大的毒性,而且比紫杉醇有更好的水溶性。全合成埃博霉素虽然可以实现,但是与发酵方法相比尚无经济可行性。现就埃博霉素生物合成基因簇的克隆和异源表达,以及对Red／ET重组技术在埃博霉素生物合成中的应用进行了详细阐述。     

埃坡霉素高产菌株的选育

采用紫外-亚硝酸盐复合诱变法对纤维堆囊菌(Sorangium cellulosum)ATCC 15384进行诱变,结合红霉素抗性筛选,筛得一株遗传稳定的埃坡霉素高产菌株纤维堆囊菌UNl6H127,埃坡霉素A(Epo A)和埃坡霉素B(Epo B)的产量为289.9和25.14μg/L,总产量(EpoA+Epo B,315.04μg/L)是出发菌株的23.8倍.     

埃坡霉素抗肿瘤作用及药动学研究

埃坡霉素是一类新型抗微管蛋白解聚类化合物,在体内外均有强大广谱的抗肿瘤活性,且对紫杉醇耐药的肿瘤有效。本文综述多种埃坡霉素类药物近年来的抗肿瘤作用及药动学研究进展。     

新型抗肿瘤药物埃坡霉素的研究

综述了近年来大环内酯类抗肿瘤药埃坡霉素的研究进展。简要介绍了其作用机制、药理活性和临床疗效，重点对埃坡霉素的构效关系以及若干种全合成策略，如大环内酯化合成、烯烃转化／stiue偶合等方法进行了分析和介绍。     

雷帕霉素及其衍生物开发现状、作用机制及生物合成研究进展

目的 介绍了近年来雷帕霉素及其衍生物的开发现状、作用机制与生物合成途径,探讨了通过前体定向生物合成与诱变生物合成的方式,获得雷帕霉素衍生物的研究进展,展望了雷帕霉素及衍生物的研究前景.方法 分析、归纳、总结近年来发表的相关文献.结果与结论 雷帕霉素及其衍生物是新型强效的免疫抑制剂与抗肿瘤药物,具有抗真菌、抗增殖及潜在延长哺乳动物寿命周期等作用.采用前体定向生物合成、诱变生物合成与组合生物合成的方式,可快速获得其具药理活性的衍生物.基于生物合成途径,采用系统生物学相关手段可获高产工程化菌种应用于工业化生产.     

埃坡霉素B对A549人肺腺癌细胞的体内外抗肿瘤药效学研究

目的:观察埃坡霉素B在体内外对A549人肺腺癌细胞生长的抑制作用。方法:用MTT法观察埃坡霉素B体外作用72h对A549人肺腺癌细胞增殖的抑制作用;用A549人肺腺癌裸鼠移植瘤模型评价埃坡霉素B在1.0、0.5、0.25mg/kg剂量下,给药2~3次后的体内抗肿瘤活性。结果:实验结果显示,埃坡霉素B在体外对人肺腺癌细胞A549抑制作用的IC50为(0.53±0.11)nmol/L,实际检测的最大抑制率为68.6%。体内实验表明受试物对A549人肺腺癌裸鼠移植瘤具有较强的抑制作用,并呈现出良好的剂量依赖性。给予1.0、0.5、0.25mg/kg受试物,第一次实验,其对A549裸鼠移植瘤的抑制率分别为78.6%、58.8%和48.3%;第二次实验,其对A549裸鼠移植瘤的抑制率分别为84.2%、76%和68.2%。阳性药物紫杉醇15mg/kg多次给药的抑瘤率分别为56.0%和85.7%。结论:埃坡霉素B在体内外对A549人肺腺癌具有较强的抑制作用。     

雷帕霉素生物合成基因簇的研究进展

雷帕霉素有效的免疫抑制作用备受关注,尤其是雷帕霉素产生菌吸水链霉菌的雷帕霉素生物合成基因簇的测定,雷帕霉素的生物合成途径得到全面系统的研究.本文从雷帕霉素基因簇出发,重点综述雷帕霉素生物合成代谢的研究进展.     

埃博霉素B、D及其衍生物的研究进展

埃博霉素是以微管为靶点的大环内酯类药物.已经或正在开发的几种埃博霉素类药物有:埃博霉素B内酰胺衍生物、埃博霉素D、埃博霉素B、埃博霉素F、埃博霉素A,其中埃博霉素D内酰胺衍生物极有可能成为高效候选抗肿瘤新药.本文从结构特点和作用机制出发,重点综述埃博霉素B、D及其衍生物的研发进展.     

Epothilones: a novel class of non-taxane microtubule-stabilizing agents

The epothilones are a novel class of non-taxane microtubule-stabilizing agents obtained from the fermentation of the cellulose degrading myxobacteria, Sorangium cellulosum. Preclinical studies have shown that the epothilones are more potent than the taxanes and active in some taxane-resistant models. Similar to paclitaxel and other taxanes, the epothilones block cells in mitosis, resulting in cell death. The chief components of the fermentation process are epothilones A and B, with epothilones C and D found in smaller amounts. Trace amounts of other epothilones have also been detected. Pre-clinical studies have shown that epothilone B is the most active form, exhibiting significantly higher antitumor activity than paclitaxel and docetaxel. Several phase I and phase II clinical trials are ongoing with epothilone B and BMS 247550, an epothilone B analog. Preliminary reports indicate these agents are active against human cancers in heavily pre-treated patients. The epothilones appear to be well tolerated, with a side effect profile that is similar to that reported with the taxanes. This article will review some basic aspects of epothilone chemistry and biology, and pre-clinical and preliminary clinical experience with epothilone B and its analog, BMS 247550.     

Novel drugs targeting microtubules: the role of epothilones

Among the drugs targeting microtubule functions by interfering with tubulin subunits, epothilones represent a class of anticancer agents which recently entered clinical development. Although epothilones share mechanisms of action similar to taxanes, they have non-overlapping mechanisms of resistance; in particular, while overexpression of class III β-tubulin plays a major role in taxane resistance, epothilones display their highest efficacy in class III β-tubulin overexpressing malignancies. Three compounds belonging to this family (patupilone, ixabepilone and sagopilone), have been actively investigated in clinical trials, and some of them are at an advanced stage of development. This review provides a comprehensive analysis of the available literature on epothilones, focusing on their clinical development and potential as an additional weapon in the arsenal against tumors.     

Studies on the biosynthesis of epothilones: the PKS and Epothilone C/D monooxygenase

Nonproducer mutants support the assumption that epothilones A and B are synthesized by the same polyketide synthase (PKS). The endproducts of the PKS, epothilones C and D, compete for the active site of a constitutively synthesized monooxygenase which is regulated by product inhibition. The postulated C-13 hydroxy-epothilones as direct precursors of epothilones C and D were not detected.     

Epothilones in the treatment of cancer

Epothilones are cytotoxic macrolides with a similar mechanism of action to paclitaxel but with the potential advantage of activity in taxane-resistant settings in preclinical models. The epothilones ixabepilone, patupilone, BMS-310705, KOS-862 and ZK-EPO are in early clinical trials for cancer treatment. Phase I studies have shown that dose-limiting toxicities of epothilones are generally neurotoxicity and neutropoenia although initial studies with patupilone indicated that diarrhoea was dose limiting. Neuropathy induced by ixabepilone may be schedule dependent. Over 20 Phase II studies of epothilones in cancer treatment have been reported, and significant activity in taxane-sensitive tumour types (such as breast, lung and prostate cancers) has been noted. Response rates in taxane-refractory metastatic breast cancer are relatively modest, but ixabepilone and patupilone have shown promising efficacy in hormone-refractory metastatic prostate cancer and in taxane-refractory ovarian cancer.     

Activity of epothilones

Epothilones represent a novel class of anticancer drugs which inhibit the cell cycle and strongly influence cell division. The biological activity of epothilones is associated with their capacity to bind to the protein tubulin of microtubules and to disturb the dynamic equilibrium between microtubule assembling and disassembling. Consequently, in dividing cells, it leads to mitotic arrest and to apoptotic cell death. A number of epothilones demonstrate a potent inhibitory effect on cell proliferation in human tumor cell lines, as well as antitumor activity in experimental animals bearing human tumor xenografts. This review will focus on the recent preclinical studies of the in vitro and in vivo activities of four epothilones, EPO-906, BMS-247550, KOS-862 and BMS-310705. Several epothilones are undergoing clinical evaluation and are promising candidates for advanced cancer therapy.     

Studies on the biosynthesis of epothilones: the biosynthetic origin of the carbon skeleton

The biosynthetic origin of the epothilone skeleton was studied by the incorporation of 13C and radioactively labeled precursors by Sorangium cellulosum So ce90. The carbon atoms are derived from acetate, propionate, the methyl group of S-adenosyl-methionine, and cysteine which also introduces the sulfur and nitrogen atoms. Epothilone biosynthesis starts with the formation of the thiazole part from acetate and cysteine. The incorporation of acetate or propionate units results in the formation of epothilones A and B, respectively. To introduce the epoxide function of epothilones A and B molecular oxygen is used.     

Discovery and development of the epothilones : a novel class of antineoplastic drugs

The epothilones are a novel class of antineoplastic agents possessing antitubulin activity. The compounds were originally identified as secondary metabolites produced by the soil-dwelling myxobacterium Sorangium cellulosum. Two major compounds, epothilone A and epothilone B, were purified from the S. cellulosum strain So ce90 and their structures were identified as 16-member macrolides. Initial screening with these compounds revealed a very narrow and selective antifungal activity against the zygomycete, Mucor hiemalis. In addition, strong cytotoxic activity against eukaryotic cells, mouse L929 fibroblasts and human T-24 bladder carcinoma cells was observed. Subsequent studies revealed that epothilones induce tubulin polymerization and enhance microtubule stability. Epothilone-induced stabilisation of microtubules was shown to cause arrest at the G2/M transition of the cell cycle and apoptosis. The compounds are active against cancer cells that have developed resistance to taxanes as a result of acquisition of beta-tubulin overexpression or mutations and against multidrug-resistant cells that overexpress P-glycoprotein or multidrug resistance-associated protein. Thus, epothilones represent a new class of antimicrotubule agents with low susceptibility to key tumour resistance mechanisms.More recently, a range of synthetic and semisynthetic epothilone analogues have been produced to further improve the adverse effect profile (or therapeutic window) and to maximize pharmacokinetic and antitumour properties. Various epothilone analogues have demonstrated activity against many tumour types in preclinical studies and several compounds have been and still are being evaluated in clinical trials. This article reviews the identification and early molecular characterization of the epothilones, which has provided insight into the mode of action of these novel antitumour agents in vivo.     

Synthesis of isotopically labeled epothilones

The epothilones, including epothilones B and D, are macrocyclic lactones, which have potent cytotoxicities and promote the polymerization of tubulin to mictotubules by binding to and stabilizing the tubulin polymer. They have a very similar mechanism of action to paclitaxel (Taxol®). The determination of the microtubule‐binding conformation of the epothilones is an important piece of information in designing improved analogs for possible clinical use, and internuclear distance information that will assist the determination of this conformation can be obtained by rotational echo double resonance (REDOR) NMR studies of microtubule‐bound epothilones with appropriate stable isotope labels. Analogs of epothilone B and epothilone D with [²H₃] and [¹⁹F] labels were prepared from an advanced precursor for potential use in REDOR NMR studies to determine internuclear distances in tubulin‐bound ligand. Copyright © 2013 John Wiley & Sons, Ltd.     

纤维堆囊菌Soce90菌株发酵合成新型抗癌物质epothilones的营养控制

Ｅｐｏｔｈｉｌｏｎｅｓ是从粘细菌纤维堆囊菌（Ｓｏｒａｎｇｉｕｍｃｅｌｕｌｏｓｕｍ）中新分离的一类具有抗肿瘤活性的次级代谢产物。本文研究了影响纤维堆囊菌Ｓｏｃｅ９０菌株合成ｅｐｏｔｈｉｌｏｎｅｓ的条件。结果表明：菌体的生长状态对产物的合成有影响，指数期接种物、低氮高碳培养条件、某些盐离子、氨基酸和乙酸盐对ｅｐｏｔｈｉｌｏｎｅｓ的合成有益。以此获得较为稳定ｅｐｏｔｈｉｌｏｎｓ产量的条件因素