基于DNA纳米花的细胞自噬基因沉默用于增敏抗肿瘤化疗

自噬是真核细胞降解蛋白质的重要途径之一,在细胞的更新代谢中起重要作用.肿瘤细胞借助高水平的细胞自噬能够阻断细胞凋亡途径,降低化疗药物的抗肿瘤效果.本文通过设计编码有核酸适配体序列(Aptamer)和DNA酶序列(DNAzyme)的多功能DNA纳米花,利用DNA序列可负载化疗药物阿霉素(Dox)的特性,实现了对肿瘤细胞特异靶向的药物递送,并高效沉默肿瘤细胞的自噬相关基因ATG5,达到增敏抗肿瘤化疗的效果.通过RT-PCR实验验证合成的DNA纳米花可以有效剪切肿瘤细胞中自噬相关基因ATG5的mRNA;并通过DNA纳米花的细胞毒性和细胞凋亡实验研究了其对肿瘤细胞系MCF-7的靶向治疗作用,结果显示该多功能DNA纳米花在增敏抗肿瘤化疗方面具有明显优势.     

快速线扫描拉曼成像技术在研究CaSki细胞凋亡过程中的应用

应用快速线扫描拉曼成像技术研究了在抗肿瘤药物顺铂诱导下宫颈癌Ca Ski细胞凋亡过程中细胞色素c、蛋白质和脂质等的时空变化规律.结果表明,细胞色素c与蛋白质的相对拉曼峰强可以反映细胞凋亡程度.与常用的表征细胞活性的噻唑蓝(MTT)实验的统计方法相比,利用拉曼成像技术可以更灵敏地观察到细胞凋亡早期生物活性分子的变化,从而在单细胞水平检测细胞凋亡过程,为解析药物与细胞的作用机制提供分子水平信息.     

用于输送siRNA的聚乙烯亚胺-聚乙二醇二丙烯酸酯纳米凝胶

阐述了一种新的用于输送小干扰核糖核酸(siRNA)的聚乙烯亚胺-聚乙二醇二丙烯酸酯纳米凝胶的合成及其表征.在反相微乳液体系中,聚乙烯亚胺(PEI)和聚乙二醇二丙烯酸酯(PEG-DA)通过麦克尔加成交联得到纳米凝胶.1H-NMR和FTIR的结果充分证明纳米凝胶的化学结构,而动态光散射则表明纳米凝胶的颗粒粒径均匀,约为180 nm,zeta电位为37.9 mV.同时,MTT结果表明纳米凝胶在高达1 mg/mL的浓度下对MCF-7细胞也基本没有毒性.凝胶阻滞实验证明纳米凝胶在体外可以通过静电相互作用稳定结合siRNA.转染实验结果表明纳米凝胶与GFP siRNA的复合物能降低MCF-7 KMRV细胞(一种能稳定表达GFP蛋白的MCF-7细胞系)GFP蛋白的表达.以上结果证明这种生物相容性的纳米凝胶可以结合并输送siRNA进入细胞,沉默相关基因的表达.     

阳离子化荧光金纳米簇的合成及siRNA递送研究

基于Small interfering RNA(siRNA)的RNA干扰(RNA interference, RNAi)策略已经成为生物医学研究的常规手段,而通常采用的基于聚阳离子或阳离子磷脂的siRNA递送系统递送效率低、细胞毒性高,而且缺少示踪功能,严重制约了siRNA药物临床转化。为克服传统siRNA递送载体的不足,本研究发展了一种新型siRNA荧光纳米递送系统。首先利用牛血清白蛋白为模板,通过生物矿化策略合成具有近红外荧光发射的金纳米簇(Gold nanocluster, GN),利用乙二胺(Ethylenediamine, EDA)或N,N-二甲基乙二胺(N,N’-Dimethylethylenediamine, DMA)对GN进行共价修饰,得到阳离子化金纳米簇(Cationic gold nanocluster, CGN),同时实现siRNA高效递送和荧光示踪。然后,以表达绿色荧光蛋白(Green fluorescence protein, GFP)的肺癌A549细胞(A549-GFP)为细胞模型,验证了CGN可实现siRNA高效递送,并沉默A549-GFP细胞的GFP表达...     

去氢枞酸异丙醇胺衍生物的合成及其细胞毒性评价

为了寻找高效的抗肿瘤活性化合物,设计合成了一系列去氢枞酸异丙醇胺类化合物,利用IR、NMR和MS对其结构进行表征。采用噻唑蓝(MTT)法评价了目标化合物对四种不同肿瘤细胞T24(人膀胱移行癌细胞)、HepG2(人肝癌细胞)、SK-OV-3(人卵巢癌细胞)、A549(人肺癌细胞)和LO2(人正常肝细胞)的抗增殖活性。结果表明,部分化合物对肿瘤细胞的抑制作用优于阳性对照顺铂。其中,化合物3d对四种细胞株表现出最好的抗增殖效果,IC₅₀值分为8.10±0.28,8.65±0.10,13.21±0.35和8.24±0.42 μmol.L_-1^{。初步机理研究表明},化合物3d使A549细胞周期阻滞在G1/G0期,并诱导A549细胞凋亡,且呈浓度依赖性。     

聚乙烯胺类修饰萘酰亚胺衍生物的合成、DNA键合行为和活性研究

合成了二乙烯三胺、三乙烯四胺和四乙烯五胺等低分子量聚乙烯胺类修饰的萘酰亚胺衍生物.通过UV-Vis谱、荧光光谱、圆二色谱和热变性试验研究了合成化合物与小牛胸腺DNA的键合行为,同时通过四甲基偶氮唑蓝(MTT)染色法研究了化合物对Bel-7402(人肝癌细胞)、HL-60(白血病细胞)、A549(人肺癌细胞)和Hela(人宫颈癌细胞)等细胞株的体外抗肿瘤活性,化合物NI1对A549细胞显示良好的抑制活性,优于阳性对照顺铂.     

尺寸排阻色谱-电感耦合等离子体质谱联用技术研究牛血清白蛋白与顺铂的反应动力学

顺铂是广泛应用的抗肿瘤药物,生理盐水稀释后通过静脉注射到体内.研究顺铂和血浆蛋白间的相互作用对理解其药效十分重要.本实验利用尺寸排阻色谱-电感耦合等离子体质谱(SEC/ICP-MS)联用技术研究了顺铂和牛血清白蛋白(BSA)的反应速率常数.顺铂与BSA于37℃孵育3,6,9,17和24 h后,用SEC/ICPMS分析顺铂及顺铂-BSA复合物铂,从而计算出顺铂和BSA的反应速率常数为0.077 h-1.方法对于铂的检出限为0.19 ng/g.     

β-咔啉-苯并咪唑偶联物的合成及抗肿瘤活性研究（英文）

为进一步发现具有更好药理活性的新型β-咔啉类抗肿瘤药物,以L-色氨酸和不同种类的醛为原料设计并合成了一系列具有不同取代基的1,9-二取代-β-咔啉-苯并咪唑偶联物.采用噻唑蓝(MTT)法评估了目标化合物对肺癌(A549)、胃癌(BGC-823)、结肠癌(CT-26)、肝癌(Bel-7402)和乳腺癌(MCF-7)等五种肿瘤细胞株的体外抗肿瘤活性,讨论了β-咔啉环1位和9位取代基对抗肿瘤活性的影响.结果显示大多数目标化合物表现出广谱的抗肿瘤活性,获得了初步的构效关系.特别是化合物5s,在β-咔啉环9位具有苄基且苯并咪唑环上具有三氟甲基取代,对MCF-7细胞株具有最好的抗肿瘤活性,其IC₅₀值为(4.9±0.3)μmol/L,抗肿瘤活性明显优于阳性对照药顺铂.化合物5c和5q对测试的3株肿瘤细胞都表现出良好的活性且IC₅₀值小于10μmol/L;细胞划痕实验结果表明这两个化合物对A549细胞横向迁移能力有一定的抑制效果     

微流控芯片药物诱导细胞凋亡

发展了一种以微流控芯片为平台的药物诱导细胞凋亡的新方法.选择HeLa细胞为对象,通过浓度梯度芯片形成稳定的药物浓度梯度,诱导HeLa细胞凋亡,利用荧光能量共振转移（fluorescence resonance energy transfer,FRET）成像系统进行实时监测,分析细胞对不同浓度化合物的毒性反应.结果表明,细胞在顺铂诱导下发生明显的起泡和皱缩,FRET比率值逐渐降低,在药物浓度梯度作用下,芯片每个通道内细胞呈现不同程度的凋亡.该方法实现了药物浓度梯度诱导细胞凋亡的实时监测和定量分析,为抗肿瘤药物评价和高通量药物筛选提供了新的手段.     

新型苯并[b]氮杂?-查尔酮杂合物的设计、合成及抗肿瘤活性研究

为了寻找高效、低毒的抗肿瘤药物，基于分子杂交的策略，将苯并[b]氮杂?结构引入查尔酮母体结构中，设计了12个未见文献报道的苯并[b]氮杂?-查尔酮杂合物（7a~7l）。并以苯胺为原料，经N-烷基化、羰基化、水解、环化和Claisen-Schmidt缩合反应合成了7a~7l，其结构经¹HNMR, ¹³CNMR和HR-MS(ESI)表征。采用MTT法评估了目标化合物对人胃癌细胞（HGC-27）、人肝癌细胞（HepG2）、人非小细胞肺癌细胞（A549）和人正常胃粘膜上皮细胞（GES-1）的抗增殖活性，并进一步采用流式细胞术和蛋白印迹法实验在细胞和蛋白水平上探究了活性最优化合物的抗肿瘤机制。结果表明：目标化合物对HGC-27细胞表现出较高的抗增殖活性，其中化合物7d对HGC-27细胞的抗增殖活性最强(IC₅₀=0.78 μmol•L^-1)，优于阳性对照顺铂(IC₅₀=7.38 μmol•L^-1)，同时其对人正常细胞GES-1的毒性较低（IC₅₀=22.77 μmol•L^-1, SI=29.19），弱于阳性对照顺铂（IC₅₀=9.51 μmol•L^-1, SI=1.29）。抗肿瘤机制研究表明:化合物7d能够将癌细胞HGC-27的细胞周期阻滞在G2/M期，并通过增加促凋亡蛋白Bax和降低抗凋亡蛋白Bcl-2的表达来诱导HGC-27细胞的凋亡。      

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.