聚乙二醇化靶向环肽的固相合成及其对阿霉素的结构修饰研究

用环肽c[CNGRC](即半胱氨酸-天冬酰胺-甘氨酸-精氨酸-半胱氨酸,其中NGR序列对肿瘤细胞有靶向作用)对阿霉素进行修饰,并且在c[CNGRC]的N端引入聚乙二醇衍生物以提高其稳定性。碘单质作为氧化剂和半胱氨酸侧链保护基的脱保护试剂,在将两个半胱氨酸的侧链保护基脱除的同时将两个巯基氧化形成二硫键,而不影响其他保护基团,从而实现在树脂上对肽的环化,为多肽环化提供了一种高效便捷的方法。多肽合成、聚乙二醇修饰及环化反应均采用固相合成法并优化了反应条件。将所制备的甲基六聚乙二醇乙酸和己酸修饰的CNGRC环肽在EDC/HOBT/NMM作用下与阿霉素连接,合成了具靶向潜力的阿霉素衍生物。     

二茂铁类环肽的合成与分子识别研究

设计并合成了两个系列含二茂铁单元的1＋1型和2＋2型类环肽，用循环伏安法研究了1＋1型二茂铁类环肽与含氧负离子和卤素负离子的包合作用。结果表明，类环肽能很好地识别这些常见的负离子。^1H NMR研究发现，类环肽对负离子的识别作用主要是通过类环肽酰胺键中氢与客体负离子形成分子间氢键实现的。     

细胞穿透环肽

细胞穿透环肽能够穿透细胞膜,特异性地靶向细胞内靶标,并具有较好的体内稳定性,因而具备很好的成药性,并受到研究者越来越多的关注。目前,主要有两种方式获得细胞穿透环肽,即从天然产物中获得和对已有的环肽或线性肽进行化学修饰。本文主要对上述两方面进行简要综述,重点介绍两类细胞穿透环肽天然产物以及通过化学修饰方法得到细胞穿透环肽的策略,并探讨细胞穿透环肽的结构-活性关系及其细胞穿透机理。     

微波促进催产素和赖氨加压素环肽的固相合成

以Rink Amide-MBHA树脂为载体, 采用Fmoc/tBu正交保护固相合成策略, 运用微波照射促进, 先快速高效地合成得到载有催产素或赖氨加压素还原型多肽的树脂, 再将连接在树脂上的各还原型多肽分别在微波促进条件下和常温条件下环合形成二硫键制得环肽, 最后用Reagent K试剂将环肽从树脂上裂解下来得到目标多肽的粗品. 利用HPLC法测定不同固相环合条件下得到的多肽粗品纯度, 结果显示经微波促进固相环合得到的多肽粗品纯度明显高于常温条件下得到的多肽粗品纯度. 粗品最后经过反相制备高效液相系统纯化并冻干得到目标多肽纯品, 通过电喷雾质谱法测定了制得的还原型多肽及相应环肽的分子量, 验证了它们的结构.     

基于Chlamydocin骨架设计合成环肽类HDACi及其抗肿瘤活性

组蛋白去乙酰化酶(HDACs)通过催化各种底物蛋白包括组蛋白、转录因子、α-微管蛋白和核输入蛋白等的ε-赖氨酸残基乙酰化侧链的去乙酰化来影响细胞功能,抑制HDAC活性可以治疗表观遗传异常引起的癌症和其他慢性疾病.以HDAC抑制剂(HDACi) Chlamydocin为骨架设计合成一类新型抑制剂,将HDACi的结合区设计为二硫键结构、在环肽中苯丙氨酸的苯环不同位点引入甲基,合成4种不同序列的环肽类HDACi.考察HDACi体外抗肿瘤细胞(MCF-7,Hela和7721)活性,结果表明HDACi对三种肿瘤细胞系均显示良好的生长抑制作用,细胞形态都发生明显变化,其中对Hela细胞的毒性最高,IC50达到0.1 μmol/L.     

二硫键桥联双二茂铁芳胺的合成及电化学性质研究

以p、m-二茂铁苯胺和p-乙酰硫基苯甲醛反应,合成了两个含p-乙酰硫苯基的二茂铁席夫碱化合物,硼氢化钠还原碳氮双键的同时对乙酰硫基脱保护,得到了两个二硫键桥联双二茂铁芳胺化合物。用熔点,红外光谱,核磁共振氢谱和高分辨质谱对相关化合物进行了结构表征。电化学循环伏安研究表明,p、m-二茂铁苯胺所形成的席夫碱及其还原脱保护产物的循环伏安性质略有差异,其中仲氨基和二茂铁处于对位的二硫键桥联双二茂铁芳胺容易失去电子。电化学研究表明,通过二硫键的均裂和Au-S键可将含刚性芳香环的二茂铁分子通过自组装的方法修饰在金电极表面,可作为潜在的生物化学传感器。     

环肽纳米管的应用研究

环肽分子通过主链骨架中C=O和N—H形成分子间网络氢键,以β-片层反平行方式堆积可形成中空管状结构。通过控制环肽的结构和尺寸,或修饰具有不同功能的基团,可获得多种结构和性能的肽纳米管。本文综述了环肽分子自组装成纳米管的应用研究成果。首先介绍了带合适疏水性侧链的环肽纳米管在模拟生物跨膜离子通道方面的实验和理论研究进展,重点论及环肽纳米管的结构、极性和侧链的疏水性等对离子通道传输行为的影响以及分子动力学(MD)模拟研究水通道的进展。进而介绍了环肽纳米管用作生物传感器模板,与功能性(如电性、光学性和磁性)纳米材料合成制备生物传感器的实验研究成果,接着介绍了环肽纳米管作为药物或药物载体潜在的应用前景,特别是在某些抗菌和抗感染药物开发设计中的应用以及环肽在不同极性环境中自组装过程微观机制的MD模拟研究,最后介绍了环肽纳米管作为模板,制备磁性、电性纳米材料方面的实验和理论研究进展。     

骨架环肽的化学合成研究进展

骨架环肽是线性肽的C端和N端通过酰胺键进行首尾环合而形成的环状分子.研究者从细菌、真菌、植物和动物中发现了大量的骨架环肽.这种首尾环合的结构,使得骨架环肽具有很好的酶稳定性、热稳定性和化学稳定性,部分骨架环肽具有细胞膜通透性.骨架环肽分子异常的稳定性和高效的生物活性,使得其成为目前药物领域的研究热点.为了更深入地研究它们的结构和功能,骨架环肽的制备成为一个重要问题.概述了化学合成骨架环肽的一些方法,包括:(1)固相环合策略;(2)液相环合策略;(3)分子内自然化学连接策略,并对这些方法的特点和效率进行了讨论比较.     

化学裂解结合生物质谱对多肽二硫键的定位

二硫键是一种与多肽及蛋白质结构和功能密切相关的化学键. 当多肽中存在多个半胱氨酸时, 形成的二硫键可能会存在多种配对方式. 快速且精准地定位多肽中多对二硫键对研究多肽的结构与功能间的关系十分重要. 本文开发了一种基于化学裂解和生物质谱的新方法, 对利那洛肽中3对二硫键进行了精准定位. 通过解析裂解后特异肽段的二级质谱图, 确定利那洛肽中3对二硫键的配对方式分别为Cys1-Cys6, Cys2-Cys10和Cys5-Cys13. 该方法为二硫键的定位研究提供了新思路.     

放线菌素D新类似物的设计、合成与体外抗肿瘤活性

为了提高临床抗肿瘤药物放线菌素D(AMD)的抗肿瘤效果和治疗指数,在AMD构效关系研究基础上,设计全合成了包括9个新类似物在内的两类共13个AMD类似物.保持环肽2位D-Val不变,环肽5位分别用Sar,D-Me-Leu和Me-Ile等氨基酸替换以改变侧链基团长度,合成了类似物8b～8e;以环肽2位D-Phe替换的低毒性类似物[D-Phe2]2AMD为基础,在环肽5位进行氨基酸替换,改变侧链基团长度和空间指向,并引入芳香族氨基酸等,合成了类似物8f～8m.优化了类似物的合成中的反应条件,提高了五肽环化产率,避免了消旋产物的生成.所有类似物经[α]D,1HNMR和高分辨质谱表征后,采用MTT法进行了体外抗肿瘤活性筛选,结果表明,保留环肽2位D-Val及延长5位氨基酸侧链基团能显著提高类似物的抗肿瘤活性,而2位D-Phe替换后类似物的抗肿瘤活性普遍下降.     

Development of an on-column enrichment technique based on C18-functionalized magnetic silica nanoparticles for the determination of lidocaine in rat plasma by high performance liquid chromatography

In this study, a novel on-column enrichment technique filled with C(18)-functionalized magnetic silica nanoparticles was successfully developed for the determination of lidocaine in rat plasma by high performance liquid chromatography (HPLC). The synthesized Fe(3)O(4)@SiO(2)-C(18) nanoparticles were locally packed into the capillary by the application of magnets. Lidocaine in the sample solutions pumped into the capillary tube could be easily adsorbed by Fe(3)O(4)@SiO(2)-C(18) through hydrophobic interaction by the interior C(18) groups, and eluted by acetonitrile solution. Different extraction conditions were investigated. Method validations including linear range, quantification limit, detection limit, precision, accuracy and recovery were also studied. The results showed that the proposed method based on on-column enrichment by Fe(3)O(4)@SiO(2)-C(18) was a novel, little solvent and efficient approach for the determination of lidocaine in the complex plasma samples.     

小分子配体诱导合成N,N-二苄基二硫代氨基甲酸镉(II)配合物及晶体结构

4,4'-联吡啶与二苄基二硫代氨基甲酸镉配合物[Cd(DBTC)₂]₂ (1)反应得到加合物[Cd(DBTC)₂(4,4'-bipy)] (2) (DBTC＝N,N-二苄基二硫代氨基甲酸), 通过晶体结构分析及红外光谱等研究其结构与性质. 结果表明: 引入小分子配体会破坏[Cd(DBTC)₂]₂ (1)的二聚结构, 加入吡啶则得到单核的吡啶加合物[Cd(DBTC)₂py] (3), 而引入4,4'-联吡啶后其结构变为新型的一维链状结构的配位聚合物2, 这种结构在二硫代氨基甲酸金属配合物中少见报道. 也比较了不同配体如吡啶及4,4'-联吡啶对Cd(II)及Zn(II)配合物结构的影响.     

Fluoride-ion acceptor properties of WSF4: synthesis, characterization, and computational study of the WSF5(-) and W2S2F9(-) anions and 19F NMR spectroscopic characterization of the W2OSF9(-) anion

The new [N(CH(3))(4)][WSF(5)] salt was synthesized by two preparative methods: (a) by reaction of WSF(4) with [N(CH(3))(4)][F] in CH(3)CN and (b) directly from WF(6) using the new sulfide-transfer reagent [N(CH(3))(4)][SSi(CH(3))(3)]. The [N(CH(3))(4)][WSF(5)] salt was characterized by Raman, IR, and (19)F NMR spectroscopy and [N(CH(3))(4)][WSF(5)]·CH(3)CN by X-ray crystallography. The reaction of WSF(4) with half an aliquot of [N(CH(3))(4)][F] yielded [N(CH(3))(4)][W(2)S(2)F(9)], which was characterized by Raman and (19)F NMR spectroscopy and by X-ray crystallography. The WSF(5)(-) and W(2)S(2)F(9)(-) anions were studied by density functional theory calculations. The novel [W(2)OSF(9)](-) anion was observed by (19)F NMR spectroscopy in a CH(3)CN solution of WOF(4) and WSF(5)(-), as well as CH(3)CN solutions of WSF(4) and WOF(5)(-).     

钌(II)多吡啶配合物的合成、荧光性质及与脱氧核糖核酸DNA的 作用机制研究

设计合成含多个配位中心的多吡啶配体ODCIP (3,4-二氯基苯并咪唑并[4,5-f][1,10]邻菲咯啉)及其钌(II)多吡啶配合物[Ru(bpy)2ODCIP]2＋. 运用元素分析、红外光谱、核磁谱和质谱对配体及配合物进行结构表征. 利用紫外吸收光谱、荧光光谱和粘度法研究了[Ru(bpy)2ODCIP]2＋与DNA(脱氧核糖核酸)的作用机制、与Co2＋配位后与DNA的作用机制及其荧光变化情况. 结果表明[Ru(bpy)2ODCIP]2＋与DNA通过部分插入模式作用, [Ru(bpy)2ODCIP]2＋与Co2＋配位形成的双核配合物[Ru(bpy)2(ODCIP)Co]4＋也能与DNA插入结合. 进一步利用稳态荧光发射光谱、荧光淬灭实验等方法研究了单核配合物[Ru(bpy)2ODCIP]2＋和双核配合物[Ru(bpy)2(ODCIP)Co]4＋的荧光性质.     

层状纳米光催化复合材料H0.8Fe0.8Ti1.2O4/TiO2的合成及性质

用固相合成法制备出K0.8Fe0.8Ti1.2O4,并用离子交换反应制备出H0.8Fe0.8Ti1.2O4;通过C3H7NH2层间膨胀,TiO2粒子的插入和紫外光分解等反应,合成出一种新的层状光催化纳米复合材料-H0.8Fe0.8Ti1.2O4/TiO2.X射线衍射和漫反射等表征结果表明 该样品的层间高度为0.47nm,禁带能隙为2.18和2.88eV.用(>400 nm的光照射30 min,0.4 g样品可使甲基橙溶液(20 mg/L)的降解率达到22.1%.而同样条件下标准TiO2(P-25)仅为6.2%,表明所研制的层状纳米复合材料具有较高的光催化活性.     

Synthesis,Structure, and Electrochemical Properties of Sterically Protected Molybdenum Trihydride Redox Pairs: A Paramagnetic “Stretched” Dihydrogen Complex?

Complexes [MoCp(#)(PMe(3))(2)H(3)] (Cp(#)=1,2,4-C(5)H(2)tBu(3), 2 a; C(5)HiPr(4), 2 b) have been synthesized from the corresponding compounds [MoCp(#)Cl(4)] (1 a, 1 b) and fully characterized, including by X-ray crystallography and by a neutron diffraction study for 2 a. Protonation of 2 a led to complex [Mo(1,2,4-C(5)H(2)tBu(3))(PMe(3))(2)H(4)](+) (3 a) in THF and to [Mo(1,2,4-C(5)H(2)tBu(3))(PMe(3))(2)(MeCN)H(2)](+) (4 a) in MeCN. Complex 4 b analogously derives from protonation of 2 b in MeCN, whereas the tetrahydride complex 3 b is unstable. One-electron oxidation of 2 a and 2 b by [FeCp(2)]PF(6) produces the EPR-active 17-electron complexes 2 a(+) and 2 b(+). The former is thermally more stable than the latter and could be crystallographically characterized as the PF(6) (-) salt by X-ray diffraction, providing evidence for the presence of a stretched dihydrogen ligand (H...H=1.36(6) angstroms). Controlled thermal decomposition of 2 a(+) yielded the product of H(2) elimination, the 15-electron monohydride complex [Mo(1,2,4-C(5)H(2)tBu(3))(PMe(3))(2)H]PF(6) (5 a), which was characterized by X-ray crystallography and by EPR spectroscopy at liquid He temperature. The compound establishes an equilibrium with the solvent adduct in THF. An electrochemical study by cyclic voltammetry provides further evidence for a rapid H(2) elimination process from the 17-electron complexes. In contrast to the previously investigated [MoCp*(dppe)H(3)](+) system (dppe=1,2-bis(diphenylphosphino)ethane; Cp*=pentamethylcyclopentadienyl), the decomposition of 2 a(+) by H(2) substitution with a solvent molecule appears to follow a dissociative pathway in MeCN.     

Determination of chromium(III) in water by solid-phase microextraction with a polyimide-coated fiber and gas chromatography-flame photometric detection

A method for the determination of trace Cr(III) in aqueous solution by solid-phase microextraction (SPME) coupled with gas chromatography (GC)-flame photometric detection (FPD) was developed. Aqueous Cr(III) was first converted to the volatile chromium trifluoroacetylacetonate (Cr(tfa)3) by derivatization with 1,1,1-trifluoroacetylacetone (Htfa), followed by SPME extraction using a polyimide-coated silica fiber. The distribution constants (K) of derivatized cis- and trans-Cr(tfa)3 between the polyimide phase and aqueous phase were 2012 and 2214, respectively. The two Cr(tfa)3 isomers extracted can be efficiently separated by a DB-210 GC column within 9 min. Selective detection of Cr was performed by a FPD equipped with a 385-nm long-pass filter. Linearity (r> 0.99) over the concentration range 5-300 ng ml(-1) Cr was obtained and the limit of detection was 2 ng ml(-1) Cr. The relative standard deviation was 7% at 10 ng ml(-1) Cr (n = 5). Applicability of this method to water analysis was tested by analyzing the chromium content in a reference standard water sample and an industrial effluent.     

Oxidation of Zn(Cys)4 zinc finger peptides by O2 and H2O2: products, mechanism and kinetics

The reactivity of a series of Zn(Cys)(4) zinc finger model peptides towards H(2)O(2) and O(2) has been investigated. The oxidation products were identified by HPLC and ESI-MS analysis. At pH<7.5, the zinc complexes and the free peptides are oxidised to bis-disulfide-containing peptides. Above pH 7.5, the oxidation of the zinc complexes by H(2)O(2) also yields sulfinate- and sulfonate-containing overoxidised peptides. At pH 7.0, monitoring of the reactions between the zinc complexes and H(2)O(2) by HPLC revealed the sequential formation of two disulfides. Several techniques for the determination of the rate constant for the first oxidation step corresponding to the attack of H(2)O(2) by the Zn(Cys)(4) site have been compared. This rate constant can be reliably determined by monitoring the oxidation by HPLC, fluorescence, circular dichroism or absorption spectroscopy in the presence of excess ethyleneglycol bis(2-aminoethyl ether)tetraacetic acid. In contrast, monitoring of the release of zinc with 4-(2-pyridylazo)resorcinol or of the thiol content with 5,5'-dithiobis(2-nitrobenzoate) did not yield reliable values of this rate constant for the case in which the formation of the second disulfide is slower than the formation of the first. The kinetic measurements clearly evidence a protective effect of zinc on the oxidation of the cysteines by both H(2)O(2) and O(2), which points to the fact that zinc binding diminishes the nucleophilicity of the thiolates. In addition, the reaction between the zinc finger and H(2)O(2) is too slow to consider zinc fingers as potential sensors for H(2)O(2) in cells.     

Strong intramolecular secondary si.N bonds in trifluorosilylhydrazines

The simple silylhydrazines F(3)SiN(Me)NMe(2) (1), F(2)Si(N(Me)NMe(2))(2) (2), and F(3)SiN(SiMe(3))NMe(2) (3) have been prepared by reaction of SiF(4) with LiN(Me)NMe(2) and LiN(SiMe(3))NMe(2), while F(3)SiN(SnMe(3))NMe(2) (4) was prepared from SiF(4) and (Me(3)Sn)(2)NNMe(2) (5). The compounds were characterized by gas-phase IR and multinuclear NMR spectroscopy ((1)H, (13)C, (14/15)N, (19)F, (29)Si, (119)Sn), as well as by mass spectrometry. The crystal structures of compounds 1-5 were determined by X-ray crystallography. The structures of free molecules 1 and 3 were determined by gas-phase electron diffraction. The structures of 1, 2, and 4 were also determined by ab initio calculations at the MP2/6-311+G** level of theory. These structural studies constitute the first experimental proof for the presence of strong Si.N beta-donor-acceptor bonds between the SiF(3) and geminal NMe(2) groups in silylhydrazines. The strength of these non-classical Si.N interactions is strongly dependent on the nature of the substituent at the alpha-nitrogen atom of the SiNN unit, and has the order 3>4>1. The valence angles at these extremely deformed alpha-nitrogen atoms, and the Si.N distances are (crystal/gas): 1 104.2(1)/106.5(4) degrees, 2.438(1)/2.510(6) A; 3 83.6(1)/84.9(4) degrees, 2.102(1)/2.135(9) A; 4 89.6(1) degrees, 2.204(2) A.     

盐酸奈法唑酮的合成

盐酸奈法唑酮是一类新型抗抑郁药.先用间氯苯胺与二乙醇胺环化合成1-(3-氯苯基)哌嗪,再与1-溴-3-氯丙烷反应制得1-(3-氯丙基)-4-(3-氯苯基)哌嗪盐酸盐,最后与5-乙基-4-(2-苯氧乙基)-1,2,4-三唑-3-酮反应得到盐酸奈法唑酮.产物结构经IR,MS,1H NMR及13C NMR确证.