中药成分五味子甲素及其金属离子复合物与血清白蛋白相互作用的研究

在模拟人体生理条件下,采用紫外光谱法、荧光光谱法和同步荧光光谱法研究五味子甲素及其金属离子复合物与血清白蛋白(SA)的结合作用。结果表明:五味子甲素与金属离子形成1∶1复合物;五味子甲素对SA的荧光猝灭机制为静态猝灭和非辐射能量转移;五味子甲素与牛血清白蛋白(BSA)和人血清白蛋白(HSA)的结合常数K、结合位点数n、结合距离r分别为3.58×104L·mol-1和6.42×103L·mol-1、0.944和0.993、2.18nm和1.63nm,其作用力以氢键和范德华力为主。同步荧光光谱法的结果表明:结合位点靠近色氨酸,并使色氨酸的疏水性减弱。共存金属离子对五味子甲素与SA的相互作用有一定的影响。     

化学发光法同时测定色氨酸和半胱氨酸的研究

基于色氨酸和半胱氨酸对Ru(pheo)32 -Ce(Ⅳ)体系化学发光的增强作用及其发光动力学性质的显著差别,提出了一种化学发光法同时测定这两种氨基酸的新方法.在优化的实验条件下,该方法测定色氨酸和半胱氨酸的线性范围分别为0.05～2.0 μg/mL和0.05～3.0 μg/mL,检出限分别为0.03 μg/mL和0.02 μg/mL.将其应用于合成样品中两种氨基酸的同时测定.结合文献提出了可能的化学发光反应机理.     

甲基苯丙胺与血清白蛋白相互作用的光谱表征

采用荧光光谱和分子对接模拟研究了甲基苯丙胺与牛血清白蛋白(BSA)之间的相互作用,发现甲基苯丙胺对BSA的荧光有明显的猝灭作用.采用分子对接的方法模拟了甲基苯丙胺与BSA的分子动力学过程.结果显示,甲基苯丙胺可能与BSA中具有内源荧光特性的色氨酸和苯丙氨酸通过静电引力发生相互作用.利用荧光光谱进一步研究了甲基苯丙胺与氨基酸的相互作用.发现甲基苯丙胺对两种氨基酸的荧光都产生了明显的猝灭作用.研究结果表明,由于静电引力的作用,甲基苯丙胺与BSA发生了结合,结合位点是BSA中的色氨酸和苯丙氨酸.     

离子液体-微乳液协同增敏荧光猝灭法测定L-色氨酸的研究

L-色氨酸是重要的氨基酸,是人体和动物生命活动中必需的氨基酸之一~([1,2]).研究以离子液体/TritonX-100-M作为共同的介质,协同增敏荧光光谱法分析L-色氨酸的新方法.在离子液体/TritonX-100-M介质中,探针体系苯基荧光酮-Se(Ⅳ)与L-色氨酸形成络合物,改变原有体系荧光强度,其荧光猝灭程度与L-色氨酸的量存在线性关系,据此建立了分析L-色氨酸方法.     

氨基酸-磷酸非共价复合物离子的电喷雾电离质谱研究

分子间的非共价相互作用对于理解分子复合物的结构和性质有着非常重要的意义。而电喷雾电离质谱(ESI-MS)是团簇化学研究的一种重要工具,广泛用于重要生物分子复合物的形成和性质研究,包括氨基酸、多肽和核糖等。该文将一定化学剂量比的磷酸分别与L型精氨酸和L型色氨酸混合,通过电喷雾电离的方法,利用傅立叶变换离子回旋共振质谱仪对精氨酸-磷酸以及色氨酸-磷酸的非共价复合物离子进行了研究。结果显示,精氨酸和色氨酸均可与磷酸分子产生种类丰富、价态为+1和+2的复合物离子。而对不同体系的生成离子分布进行分析,则显示出不同体系间的差别。     

荧光光谱法研究亚甲蓝与三种芳香族氨基酸的相互作用

本文运用荧光光谱法研究亚甲蓝(MB)分别与色氨酸(Trp)、酪氨酸(Tyr)和苯丙氨酸(Phe)三种芳香族氨基酸的相互作用。在pH 7.4 Tris-HCl缓冲溶液中,MB引起上述三种氨基酸明显的荧光猝灭现象,最大荧光猝灭波长分别位于346、303和282nm。其荧光猝灭值(F0-F)在一定范围内与MB成正比,用于测定MB具有高灵敏度。通过Stern-Volmer作图及温度的影响,表明MB与三种芳香族氨基酸之间以摩尔比1∶1形成基态复合物,均产生显著的静态猝灭,相互作用力较强,其中MB主要通过疏水作用与Trp结合,与Tyr和Phe之间的结合过程以静电作用力为主。     

ATP与氨基酸弱相互作用的质谱与理论计算研究

利用电喷雾质谱、荧光、核磁和理论计算研究了ATP与19种氨基酸的弱相互作用.在质谱中发现除甘氨酸(Gly)、丙氨酸(Ala)、缬氨酸(Val)外,其它氨基酸均可观测到与ATP因弱相互作用形成的复合物离子.利用不同质谱锥孔电压下复合物稳定性的不同,分析了侧链基团对ATP与19种氨基酸弱相互作用的影响.并利用荧光光谱和核磁共振波谱法研究了芳香性氨基酸与ATP的弱相互作用.结果表明,氨基酸与ATP的弱相互作用强弱顺序为:色氨酸(Trp)＞苯丙氨酸(Phe)＞具有R‖C-NH2的氨基酸＞具有-RCOOH、-R-NH2的氨基酸＞具有-RSH、-ROH的氨基酸＞R为长链的氨基酸＞R为短链的氨基酸.不同官能团的氨基酸与ATP的弱相互作用的模拟计算也证实了此结论,并发现氨基酸的主侧链基团与ATP分子基团间的多个分子间因氢键作用使复合物能稳定存在.这一结果将为预测蛋白与ATP结合位点及研究ATP的识别机理提供依据.     

二阶导数紫外吸收光谱测定复合氨基酸注射液中的色氨酸和苯丙氨酸的含量

复合氨基酸注射液是含有11种氨基酸及甘露醇的复方制剂。文献曾报导用二阶导数光谱测定蛋白质及天然物中的色氨酸;徐绪温等使用双波长分光光度计,用导数光谱法测定了复合氨基酸注射液中色氨酸,本文提出用二阶导数光谱直接测定色氨酸和苯丙氨酸含量的方法。实验方法 (一)仪器与试剂所用仪器为岛津UV-240型自记式紫外分光光度计OP1-1附件。氨基酸标准物均为广州侨光制药厂提供的日本进口试剂,按药典检定合格;甘露醇,分析纯。复合氨基酸注射液由广州侨光制药厂提供,为内含11种氨基酸及甘露醇的无菌水溶液,     

瓜环对氨基酸的分子识别研究

使用¹H NMR和UV-Vis光谱法研究了七、八元瓜环对九种天然氨基酸盐酸盐的分子识别作用. 结果表明, 瓜环对芳香侧基取代的L-酪氨酸、L-色氨酸、L-苯丙氨酸均能进行有效识别, 而侧链上不带芳香基团的氨基酸, 如L-组氨酸、L-谷氨酸、L-蛋氨酸、L-缬氨酸、L-白氨酸、L-丙氨酸, 与这些瓜环的作用相对较弱. 对于七元瓜环, 主客体间都以1∶1化学计量比形成包结物, 并得到它们相互作用的稳定常数; 八元瓜环与L-酪氨酸及L-色氨酸也以1∶1形成包结物, 而与L-苯丙氨酸以1∶2形成包结物. L-酪氨酸、L-色氨酸和L-苯丙氨酸荧光性质研究表明, 七、八元瓜环既可成为这些氨基酸荧光性质的增敏试剂, 也可成为它们荧光淬灭试剂, 这与氨基酸的结构有关.     

硫酸锌与α-氨基酸的相化学及其新相的合成和表征

α 氨基酸锌作为添加剂在药物、食品和化妆品等方面都有广阔的应用前景[1,2 ] 。有关氨基酸锌的合成方法前文[3] 已述及。而用相平衡方法研究锌盐与氨基酸的配合行为的相化学[4] ,对新型配合物 ,特别是固液异成分化合物的合成有指导意义。本文对ＺｎＳＯ4与人体必需而非自生的Ｌ 亮氨酸 (Ｌ Ｌｅｕ)、Ｌ 色氨酸 (Ｌ Ｔｒｙ)、Ｌ 苏氨酸 (Ｌ Ｔｈｒ)和Ｌ 缬氨酸 (Ｌ Ｖａｌ)在水中的等温溶度性质进行了研究 ,构制了其相图 ,讨论了未形成化合物的原因。合成了未见报道的Ｚｎ(Ｌｅｕ)ＳＯ4·0 .5Ｈ2 Ｏ ,Ｚｎ(Ｖａｌ)ＳＯ4·Ｈ2 Ｏ和固态配合物…     

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.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

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.     

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.     

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.     

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.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.