Inhibitory effects on HIV-1 protease of tri-p-coumaroylspermidine from Artemisia caruifolia and related amides.

From a methanol extract of Artemisia caruifolia, which showed a moderate inhibitory activity on HIV-1 protease in a preliminary screening, N1,N5,N10-tri-p-coumaroylspermidine and three dicaffeoylquinic acids were isolated. The former compound was found to appreciably inhibit HIV-1 protease. Of related amides which were chemically synthesized, N1,N5,N10,N14-tetra-p-coumaroylspermine and N1,N4,N7,N10,N13-penta-p-coumaroylte-traethylenepentamine inhibited HIV-1 protease more potently than N1,N5,N10-tri-p-coumaroylspermidine.     

渤海稠油及其组分中杂原子化合物的负离子电喷雾-高分辨质谱分析

采用沉淀法和色谱分离法将渤海某油田稠油分离成沥青质、胶质、剩余分3个组分。采用负离子电喷雾技术(ESI)结合高分辨傅立叶变换离子回旋共振质谱仪(FT-ICR MS)研究了该稠油及各组分的分子组成。结果表明,剩余分中有较少的极性杂原子化合物能被负离子ESI电离,如N_1,N_1O_1,O_1和O_2类,其等效双键数(DBE)较小。胶质和原油中极性化合物有相同的杂原子类型,包括N_1,N_1O_1,N_1O_2,N_2,N_2O_2S_1,O_1,O_2,其中胶质和原油中N_1,O_1,O_2类化合物的DBE-碳数分布图相似。沥青质中富集高缩合度且多杂原子的酸性化合物,如含杂原子N_,S的氧化程度高的化合物(N_2O_1,N_1O_3,S_1O_3)及O_3类化合物,这些物质具有较高的界面活性,易吸附在界面上促进界面张力降低和增强界面膜强度,从而有利于乳状液稳定存在。N_1O_1,N_1O_2,N_1O_3类化合物,N_2O_1类化合物可能分别是N_1化合物,N_2化合物的氧化降解产物;随着氧化降解程度增加,降解产物的极性明显增强。     

高分辨质谱解析委内瑞拉奥里常渣减黏反应杂原子化合物组成变化

运用电喷雾-傅里叶变换离子回旋共振质谱仪(ESI-FT-ICR MS),研究委内瑞拉奥里常渣减黏裂化反应前后杂原子组成及分布.常渣中O2类化合物的相对丰度最大,减黏裂化反应使O2、O1、N1O2、S1、O1S1、O2S1类化合物减少,甚至消失,而N1、N2、N2O1、N2S1、N3、N3O1、N1S2类化合物增多,减黏...     

End-growth/evaporation living polymerization kinetics revisited

End-growth/evaporation kinetics in living polymer systems with "association-ready" free unimers (no initiator) is considered theoretically. The study is focused on the systems with long chains (typical aggregation number N ? 1) at long times. A closed system of continuous equations is derived and is applied to study the kinetics of the chain length distribution (CLD) following a jump of a parameter (T-jump) inducing a change of the equilibrium mean chain length from N(0) to N. The continuous approach is asymptotically exact for t ? t(1), where t(1) is the dimer dissociation time. It yields a number of essentially new analytical results concerning the CLD kinetics in some representative regimes. In particular, we obtained the asymptotically exact CLD response (for N ? 1) to a weak T-jump (ε = N(0)∕N - 1 ? 1). For arbitrary T-jumps we found that the longest relaxation time t(max?) = 1∕γ is always quadratic in N (γ is the relaxation rate of the slowest normal mode). More precisely t(max?)∝4N(2) for N(0) < 2N and t(max?)∝NN(0)∕(1 - N∕N(0)) for N(0) > 2N. The mean chain length N(n) is shown to change significantly during the intermediate slow relaxation stage t(1) ? t ? t(max?). We predict that N(n)(t)-N(n)(0)∝√t in the intermediate regime for weak (or moderate) T-jumps. For a deep T-quench inducing strong increase of the equilibrium N(n) (N ? N(0) ? 1), the mean chain length follows a similar law, N(n)(t)∝√t, while an opposite T-jump (inducing chain shortening, N(0) ? N ? 1) leads to a power-law decrease of N(n): N(n)(t)∝t(-1∕3). It is also shown that a living polymer system gets strongly polydisperse in the latter regime, the maximum polydispersity index r = N(w)∕N(n) being r? ≈ 0.77N(0)∕N ? 1. The concentration of free unimers relaxes mainly during the fast process with the characteristic time t(f) ～ t(1)N(0)∕N(2). A nonexponential CLD dominated by short chains develops as a result of the fast stage in the case of N(0) = 1 and N ? 1. The obtained analytical results are supported, in part, by comparison with numerical results found both previously and in the present paper.     

Understanding the acid-base properties of adenosine: the intrinsic basicities of N1, N3 and N7

Adenosine (Ado) can accept three protons, at N1, N3, and N7, to give H(3) (Ado)(3+) , and thus has three macro acidity constants. Unfortunately, these constants do not reflect the real basicity of the N sites due to internal repulsions, for example, between (N1)H(+) and (N7)H(+). However, these macroconstants are still needed for the evaluations and the first two are taken from our own earlier work, that is, pK(H)(H(3))((Ado)) = -4.02 and pK(H)(H(2))((Ado)) = -1.53; the third one was re-measured as pK(H)(H)((Ado)) = 3.64 ± 0.02 (25 °C; I=0.5 M, NaNO(3)), because it is the main basis for evaluating the intrinsic basicities of N7 and N3. Previously, contradicting results had been published for the micro acidity constant of the (N7)H(+) site; this constant has now been determined in an unequivocal manner, and that of the (N3)H(+) site was obtained for the first time. The micro acidity constants, which describe the release of a proton from an (N)H(+) site under conditions for which the other nitrogen atoms are free and do not carry a proton, decrease in the order pk(N7-N1)(N7(Ado)N1·H)) = 3.63 ± 0.02 > pk(N7-N1)(H·N7(Ado)N1) = 2.15 ± 0.15 > pk(N3-N1,N7)(H·N3(Ado)N1,N7) =1.5 ± 0.3, reflecting the decreasing basicity of the various nitrogen atoms, that is, N1>N7>N3. Application of the above-mentioned microconstants allows one to calculate the percentages (formation degrees) of the tautomers formed for monoprotonated adenosine, H(Ado)(+) , in aqueous solution; the results are 96.1, 3.2, and 0.7% for N7(Ado)N1·H(+), (+)H·N7(Ado)N1, and (+)H·N3(Ado)N1,N7, respectively. These results are in excellent agreement with theoretical DFT calculations. Evidently, H(Ado)(+) exists to the largest part as N7(Ado)N1·H(+) having the proton located at N1; the two other tautomers are minority species, but they still form. These results are not only meaningful for adenosine itself, but are also of relevance for nucleic acids and adenine nucleotides, as they help to understand their metal ion-binding properties; these aspects are briefly discussed.     

The use of a diammonium salt in the synthesis of organic carbonates from epoxides and CO2: promoting effect of support

Russian Chemical Bulletin - Onium salt, N1, N1, N1, N5, N5, N5-hexaethylpentane-1,5-diammonium dibromide, was used as a catalyst for the addition of CO2 to epoxides. An influence of insoluble...     

Synthesis and insecticidal evaluation of N‐tert‐butyl‐N′‐thio[O‐(1‐methylthioethylimino)‐N″‐methylcarbamate]‐N,N′‐diacylhydrazines

A series of novel N‐tert‐butyl‐N′‐thio[O‐(1‐methylthioethylimino)‐N″‐methylcarbamate]‐N,N′‐diacylhydrazines were synthesized by the reaction of chlorosulfenyl[O‐(1‐methylthioethylimino)‐N‐methylcarbamate] with N‐tert‐butyl‐N,N′‐diacylhydrazine in the presence of sodium hydride. The reaction of sulfur dichloride with O‐(1‐methylthioethylimino)‐N‐methylcarbamate (Methomyl) in the presence of pyridine to yield chlorosulfenyl[O‐(1‐methylthioethylimino)‐N‐methylcarbamate] was reported for the first time. X‐ray single crystal diffraction of N‐tert‐butyl‐N′‐thio[O‐(1‐methylthioethylimino)‐N″‐methylcarbamate]‐N,N′‐dibenzoylhydrazine demonstrated that the parent compounds N‐tert‐butyl‐N,N′‐dibenzoylhydrazine and O‐(1‐methylthioethylimino)‐N‐methylcarbamate were combined by N S N band to give the product. Their larvicidal activities against Oriental armyworm and Aphis laburni were evaluated. All of them exhibited excellent larvicidal activities against Oriental armyworm, with some of them showing higher larvicidal activities than the parent diacylhydrazines. Toxicity assays indicated that the products show knockdown activity for O‐(1‐methylthioethylimino)‐N‐methylcarbamate at higher concentration and insect growth regulators' activities of diacylhydrazines at lower concentrations. At the same time, the products possess insecticidal activities against the aphids. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:631–636, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20360     

双季铵盐化合物的结构表征与抗菌性能测试

将N,N-二甲基乙醇胺、N-甲基二乙醇胺分别接枝到1,3-二溴丙烷的两端进行季铵化反应,得到N1,N3-二羟乙基-N1,N1,N3,N3-四甲基-1,3-丙二胺二溴盐(QAS-1)和N1,N1,N3,N3-四羟乙基-N1,N3-二甲基-1,3-丙二胺二溴盐(QAS-2)。采用傅立叶变换红外光谱(FTIR)、核磁共振(NMR)和元素分析确证了其结构,以抑菌圈法和试管二倍稀释法评价了两者对5种菌株的抗菌活性。结果显示,它们对所选菌株均具有一定的抗菌活性,其中对白色念珠菌的最小抑菌浓度(MIC)分别为100 mg·L~(-1)和50 mg·L~(-1)。扫描电子显微镜(SEM)和透射电子显微镜(TEM)显示,QAS-1对金黄色葡萄球菌的抗菌作用机理可能为,带正电荷的季铵盐吸附在细菌表面,破坏细胞膜,导致细胞质外流从而杀灭细菌。细胞毒性显示QAS-1对人正常肝细胞(LO2)和人永生化表皮细胞(HaCat)的IC_(50)值分别为110.34 mg·L~(-1)和92.68 mg·L~(-1),细胞毒性显著低于阳性药。该研究说明该类季铵盐在抗菌领域具有潜在的应用价值。     

Binding interaction analysis of the active site and its inhibitors for neuraminidase (N1 subtype) of human influenza virus by the integration of molecular docking, FMO calculation and 3D-QSAR CoMFA modeling

Recently, the worldwide spread of A/H5N1 avian influenza with high virulence has highlighted the potential threat of human influenza pandemic. Tamiflu and Relenza are currently the only two anti-influenza drugs targeting the neuraminidase (NA) enzyme of human influenza virus. Reports of the emergence of drug resistance further make the development of new potent anti-influenza inhibitors a priority. The X-ray crystallographic study of A/H5N1 avian influenza NA subtypes (Russell, R. J. Nature 2006, 443, 45-49) has demonstrated that there exist two genetically distinct groups, group-1 (N1, N4, N5 and N8) and group-2 (N2, N3, N6, N7 and N9), whose conformations are substantially different. The detailed comparison of their active sites has established, heretofore, the most accurate and solid molecular basis of structure and mechanism for the development of new anti-influenza drugs. In the present study, a three-dimensional structure of N1 subtype of human influenza type A virus (N1hA) has been generated by homology modeling using the X-ray crystallographic structure of N1 subtype of avian influenza virus (N1aA) as the template. Binding interaction analysis between the active site and its inhibitors has been performed by combining ab initio fragment molecular orbital (FMO) calculations and three-dimensional quantitative structure-activity relationship with comparative molecular field analysis (3D-QSAR CoMFA) modeling. Integrated with docking-based 3D-QSAR CoMFA modeling, molecular surface property (electrostatic and steric) mapping and FMO pair interaction analysis, a set of new receptor-ligand binding models and bioaffinity predictive models for rational design and virtual screening of more potent inhibitors of N1hA are established. In addition, the flexibility of the loop-150 of N1hA and N1aA has been examined by a series of molecular dynamics simulations.     

Relative Contributions of Diabatic and Adiabatic Channels to Photoisomerization and Photocyclization of Diarylethylenes

Relative contributions of diabatic and adiabatic channels to photoisomerization and photocyclization processes were measured for stilbene, 1-phenyl-2-(2-naphthyl)ethylene (Ph-2N), 1,2-di-(1-naphthyl)ethylene (1N-1N), 1-(1-naphthyl)-2-(2-naphthyl)ethylene (1N-2N), and 1,2-di-(2-naphthyl)ethylene (2N-2N) by the steady-state spectrophotometric method in solutions at room temperature. The effects of solvent nature and atmospheric oxygen on the quantum yields of these processes in 1N-1N and 2N-2N were studied.     

Single-molecule-force spectroscopy study of the mechanism of interactions between TSP-1 and CD47

The 4N1K peptide,which is derived from the C-terminal domain of thrombospondin-1(TSP-1),is usually used as a functional mimic peptide for TSP-1.Knowledge about the interaction force of 4N1K/CD47 is important in explaining how TSP-1 affects the biological effect of CD47.Here we used a single-molecule force spectroscopy(SMFS)technique to explore the interaction of 4N1K/CD47 on both normal and oxidative human red blood cells(h RBCs)at single-molecule level.There was no interaction force between 4N1K and CD47 on normal h RBCs;however,we did find 4N1K-bound CD47 on oxidative h RBCs.We also detected interaction forces for 4N1K/CD47ex(extracellular domain of human CD47),and 4N1K/oxidative CD47ex.The interaction forces of 4N1K/CD47ex were almost consistent with those of 4N1K/oxidative CD47ex at the same loading rate.These results suggest that the conformational change of CD47 is critical for 4N1K-CD47 interaction on oxidative h RBCs.     

亚乙烯基嘌呤核苷衍生物的合成、荧光和生化性质的研究进展

综述了亚乙烯基核苷衍生物(1,N⁶-亚乙烯基腺苷, N²,3-亚乙烯基腺苷, 1,N²-亚乙烯基鸟苷, N²,3-亚乙烯基鸟苷, 1,N⁶-亚乙烯基脱氧腺苷, 1,N²-亚乙烯基-2'-脱氧鸟苷, N²,3-亚乙烯基-2'-脱氧鸟苷)的研究进展, 讨论了其荧光性质和生物活性的应用, 展望了新型荧光扩环核苷衍生物的合成及其在荧光探针和高效药物筛选方面的研究前景.     

Metallderivate von Molekülverbindungen. VI. Lithium- und (Tetrahydrofuran)lithium-cyantrimethylsilylamid — Synthese und Struktur

Metal Derivatives of Molecular Compounds. VI. Lithium and (Tetrahydrofuran)lithium Cyanotrimethylsilylamide — Syntheses and Structures At different temperatures N,N′-bis(trimethylsilyl)carbodiimide ( 1 ) and lithium methanide react either under addition or substitution. When compound 1 , however, is treated at ?40°C with an equimolar amount of (1,2-dimethoxyethane-O,O′)lithium phosphanide ( 2 ) in 1,2-dimethoxyethane, only exchange of one trimethylsilyl group versus lithium is observed and in addition to phosphane and tris(trimethylsilyl)phosphane a very pure lithium derivative insoluble in n-pentane can be isolated. The vibrational spectra prove the compound to be lithium cyanotrimethylsilylamide ( 3 ). Recrystallization from tetrahydrofuran (+40/+20°C) yields (tetrahydrofuran)lithium cyanotrimethylsilylamide ( 3 ′). As shown by an X-ray structure analysis {C2/c; a = 2 261.1(5); b = 1 106.4(2); c = 1 045.9(2) pm; β = 113.63(1)°; Z = 8 formula units}, compound 3 ′ is polymeric in the solid state. Coordinative Li? N2′ bonds allow a head-to-tail addition of two monomeric units each to give an eight-membered heterocycle with two linear N1? C2≡N2 fragments (N1? C2 126.1; C2≡N2 117.5; N1? Si 171.4; Li? N1 203.2; Li? N2′ 206.1 pm; C2? N1? Li 109.0; N1? Li? N2′ 115.9; N2≡C2? N1 177.2°). Forming planar four-membered Li? N2? Li? N2 rings (Li? N2″″ 198.3 pm; Li′? N2? Li″ 80.3; N2′? Li? N2″″ 99.5°) these heterocycles polymerize to slightly folded tapes.     

Terminal bis-acetylenes derived from 1,2-bis(1<Emphasis Type="Italic">H</Emphasis>-tetrazol-5-yl)ethane

The N(1)—N(1), N(2)—N(2), and N(1)—N(2) regioisomers of 1,2-bis[(prop-2-yn-1-yl)-1H-tetrazol-5-yl]ethane were first synthesized by alkylation of 1,2-bis(1H-tetrazol-5-yl)ethane with propargyl bromide. The peculiarities of the crystal structure of 1,2-bis[1-(prop-2-yn-1-yl)-1H-tetrazol-5-yl]ethane were evaluated by X-ray diffraction analysis. This compound is readily underwent Cu-catalyzed [3+2] cycloaddition with p-tolyl azide, p-nitrophenyl azide, and benzyl azide to give heterocyclic assembles bearing 1,2,3-triazole and tetrazole cycles. Catalyst-free [3+2] cycloadditions of 1,2-bis[1-(prop-2-yn-1-yl)-1H-tetrazol-5-yl]ethane and the mixtures of the N(1)—N(1), N(2)—N(2), N(1)—N(2) regioisomers with poly(glycidyl azide) oligomers resulted in 1,2,3-triazole cycles and crosslinking of the polymer chains.     

具有Gemini表面活性ATRP引发剂的合成

以2-溴异丁酰溴、N,N-二甲基乙醇胺、1,6-二溴己烷为主要原料,通过两步反应合成了一种新型具有Gemini表面活性的ATRP引发剂——N1,N6-双[2-(2-溴异丁酰氧基)乙基]-N1,N1,N6,N6-四甲基己烷-1,6-二溴化铵,总收率70%,其结构经1H NMR,IR和元素分析表征。     

Dimerization of organic free radicals in solution. 1. Temperature dependent measurements

Dimerization enthalpies and equilibrium constants have been determined for the radical anion of 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), the radical cations of N,N,N',N'-tetramethyl-p-phenylenediamine, N,N-dimethyl-p-phenylenediamine, 2,3,5,6-tetramethyl-p-phenylenediamine, N,N,N',N'-tetraethyl-p-phenylenediamine, N,N-diethyl-p-phenylenediamine and N,N,N'-trimethyl-p-phenylenediamine. Neutral radicals investigated are 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and galvinoxyl. Solvent used was acetone, EtOH/Et2O-mixture (2:1 volume), propionitrile/butyronitrile-mixture (1:1 M) and dichloromethane. Measured dimerization enthalpies deltaHdim vary from -72.1 to -16.6 k/mol.     

活性氮与SO2和SOCl2的传能反应

在流动余辉装置上, 研究了活性氮与SO2和SOCl2之间的反应过程. 在280～500 nm, 观察到了SO2( A1A2,B1B1→X1A1 )和SO2(a3B1→X1A1)的发射光谱. 对比由Ar(3P0,2)与N2碰撞反应产生的纯N2(A3Σu+)与SO2、SOCl2之间反应的实验结果, 可以说明, N2(A3Σu+)在活性氮与SO2的反应中是主要的能量载体, 它与SO2的直接能量转移反应形成了激发态的SO2(A1A2, B1B1); 在活性氮与SOCl2的反应中观测到的激发态SO2(a3B1), 则可能主要是通过N(4S)与SOCl2反应生成的N2O(X1Σ+)和N2(A3Σu+)与SOCl2反应生成的SO(X3Σ－)之间的化学反应过程产生.     

Probing the vibrational spectroscopic properties and binding mechanism of anti-influenza agent Liquiritin using experimental and computational studies

Research on Chemical Intermediates - Liquiritin is an anti-viral agent of H1N1 and H3N2 influenza A virus which was reported to inhibit H1N1 and H3N2 NA enzyme with IC50 value of 82.3 and...     

多氮杂大环配体La~(3+)、Gd~(+3)络合物的合成

在NaOH存在下，N，N′，N″，N-四乙酸-1，4，7，10-四氮杂环十二烷、N，N′，N″，N-四乙酸-1，4，8，11-四氮杂环十四烷、N，N′，N″，N-四甲磷酸-1，4，7，10-四氮杂环十二烷和N，N′，N″，N-四甲磷酸-1，4，8，11-四氮杂环十四烷分别与LaCl3·7H2O或GdCl3·6H2O通过大环配体络合物直接合成法，得到八个络合物，产率为46．7％～90．7％。     

Synthese,Struktur und einige Reaktionen [N-(N′,N′,N″,N″-tetramethyl)-guanidinyl]-substituierter Phosphorylverbindungen

Synthesis, Structure, and some Reactions of N-(N′,N′,N″,N″-tetramethyl)guanidinyl-substituted Phosphoryl Compounds The tetramethylguanidinyl-substituted phosphoryl compounds 1 – 10 were prepared in the reaction of the appropriate chlorophosphoryl compounds with either N′,N′,N″,N″-tetramethylguanidine (HTMG) or N-trimethylsilyl-(N′,N′,N″,N″-tetramethyl)guanidine (TMSTMG). With methyl iodide 1 reacted with N-alkylation to give the ammonium salt 11. 1 reacted with BF₃ · Et₂O at both imino nitrogen atoms with formation of the bis-BF₃-adduct 12 . The X-ray structure determination of phenylphosphonic acid-bis(N′,N′,N″,N″-tetramethylguanidinide) 3 shows shortened PN-bonds and widened PNC-angles, consistent with the partial double bond character of the PN-bond.