四齿四棱草根部的两个新二萜化合物

通过硅胶柱层析从我国特有属植物四齿四棱草(Schnabelia tetradonta)根部乙醇提取物中分离纯化出2个新的17(15→16)-移-20-降松香烷型二萜化合物,分别命名为四棱草内酯A和B.经波谱分析,将它们的结构确定为17(15→16)-移-20-降松香烷-12,16-环氧-7,17-二羟基-5(10),6,8,12,15-五烯-11,14-二酮-18(1)-内酯(1)和17(15→16)-移-20-降松香烷-12,16-环氧-7-羟基-5(10),6,8,12,15-五烯-11,14-二酮-18(1)-内酯(2).具有这种分子骨架的二萜化合物为首次报道.     

四棱草环肽C和D的ESIMS-MS分析

利用低能量碰撞诱导解离(CID)技术对四棱草环肽C和四棱草环肽D的电喷雾电离串联质谱(ESIMS-MS)进行了研究.ESIMS可以确定环肽的分子量,根据多级质谱中逐次失去氨基酸残基的碎片离子可以确定环肽中氨基酸残基的连接顺序.氨基酸残基主要从酰氨键C端断裂失去,有时亦会从N端断裂失去氨基酸残基.     

低对称性硫代烃基四氮杂卟啉的合成、表征及电化学性质研究

合成了硫代烃基四氮杂卟啉2,3,7,8,12,13-六(甲硫基)-17,18-一(二噻英)四氮杂卟啉[H₂Pz(dtn)(mt)₆]及其过渡金属配合物MPz(dtn)(mt)₆,由元素分析、质谱、¹HNMR、UV-Vis和IR光谱对其组成和结构进行了表征,通过循环伏安测试结果讨论了H₂Pz(dtn)(mt)₆的电化学性质,证明H₂Pz(dtn)(mt)₆的还原过程为单电子连续传输过程,属于CE机理.研究了H₂Pz(dtn)(mt)₆对正极材料MnO₂在锂离子电池中的修饰作用.结果表明,H₂Pz(dtn)(mt)₆对改善锂离子电池的初始充放电容量和循环次数都有明显的增加.     

四棱草中两个新的齐墩果烷型三萜

从中国特有四棱草属药用植物四棱草中分离得到两个新的齐墩果烷型三萜,命名为2β,3β,24-三羟基-13(18)-齐墩果烯(1)和3β-羟基-13(18)-烯-24-齐墩果酸(2),其结构通过HR-ESIMS,1D和2D NMR等光谱技术确定.     

草酸-草酰胺混合桥联Mn(Ⅱ)-Cu(Ⅱ) 一维配合物的合成、晶体结构与磁性

合成了1个草酸-草酰胺混合桥联的双异金属配合物[Cu(L)(H₂O)Mn(C₂O₄)]·4H₂O(H₂L为1,4,8,11-四氮杂环十四烷-2,3-二酮). 配合物由[Cu(Ⅱ)L(H₂O)], Mn(Ⅱ), 草酸根和晶格水分子构成. Mn(Ⅱ)通过草酸根的交替桥联作用形成弯折的中性一维链状骨架[Mn(C₂O₄)]_n, 而Mn(Ⅱ)剩余的2个配位点则由[CuL]上的2个草酰胺氧原子占据, 形成了草酸-草酰胺混合桥联一维双金属配合物. 而Cu(Ⅱ)为五配位, 轴向上由1个水分子占据. 磁性研究表明, 配合物中Cu(Ⅱ)-Mn(Ⅱ)间通过草酰胺传递反铁磁相互作用, 而Mn(Ⅱ)-Mn(Ⅱ)间亦通过草酸根离子存在反铁磁耦合. 通过MAGPACK软件对变温磁化率进行拟合, 得到J_Cu-Mn=-13.1 cm^-1, J_Mn-Mn=-0.87 cm^-1, g=2.01.     

含杂环残基及非经典环化RGD相关肽的合成

以不同的非天然结构代替RGD (Arg-Gly-Asp, 精氨酰甘氨酰天冬氨酸)相关肽中的Arg残基, 共合成了11个改构的RGD相关肽. 其中1～8为杂环残基肽, 9及10为局部杂环肽, 11为主链环肽. 在合成方式上, 产物1～8由传统溶液法制备, 9～11经固相法制备. 全部产物均由MS分析证明结构. 通过本研究, 为探索新型环肽合成提供了有价值的实验基础.     

两个双四唑胺的铜配合物的合成、结构及荧光性质(英文)

用Demko-Sharpless方法自制的双四唑胺配体,再混以乙二胺和丙二胺螯合配体,合成了2个新颖的铜的配合物Cu(bta)(en)(H2O)(1)与Cu(bta)(1,3-pda)(H2O)(2)。X-射线单晶衍射表征了2个配合物的结构。2个配合物的水溶液都表现出了双四唑胺配体的特征吸收波长与荧光发射波长。     

基于2,5-双（四唑）对苯二甲酸的两种碱土金属配位聚合物的晶体结构和性质（英文）

基于2,5-双(四唑)对苯二甲酸配体采用水热法合成了两种新型配位聚合物：[Mg(dtztp)_0.5(DMF)(H₂O)₂]·H₂O(1)和[Ba(dtztp)_0.5(H₂O)₂](2)。采用单晶X射线衍射、元素分析、红外光谱和X射线粉末衍射对其结构进行表征。这两个配合物均属于三斜晶系、P-1空间群。采用差示扫描量热法(DSC)和热重分析法(TG)研究其热稳定性，1和2的分解温度分别为344℃和419℃,主体框架开始坍塌的温度分别为260℃和380℃。采用Kissinger和Ozawa方法计算了配合物热分解的动力学参数，得到了配合物1和2的机理方程。此外，利用上述结果对两种材料的热安全性进行了研究，得到了它们的自热分解温度、热着火和热爆炸临界温度。     

四氮杂-18-冠-6的锌/铜(Ⅱ)配合物的合成与结构

合成了1,10-二氧-4,7,13,16-四氮杂-18-C-6(以下用L代表)的硝酸锌和硝酸铜(Ⅱ)配合物.配合物Cu(L)(NO3)₂晶体属正交晶系,Pbca空间群,晶胞参数如下:a=1.5744(6)nm,b=1.2676(4)nm,c=1.8983(6)nm,V=3.789(2)nm³,Z=8,最终偏离因子R₁=0.0431,wR₂=0.0904.配合物Zn(L)(NO₃)₂晶体属正交晶系,Pnna空间群,晶胞参数a=1.61356(10)nm,b=1.32871(11)nm,c=0.86260(5)nm,V=1.8494(2)nm³,Z=4,最终偏离因子R₁=0.0718,wR₂=0.1950.冠醚环上的4个氮原子和2个氧原子都参与了配位,NO₃^-未参与配位,中心金属离子的配位数为6.红外光谱、¹H NMR和EPR谱等研究佐证了上述测定结果.Cu(L)(NO₃)₂循环伏安实验表明该配合物在-1.0～0V电压范围内,只发生Cu(Ⅱ)→Cu(Ⅰ)的还原反应,而在-1.6～0V电压范围内,发生Cu(Ⅰ)→Cu(0)的反应.     

1,2-双(四甲基环戊二烯基)四甲基二硅烷与六碳基钼的反应

1,2-双(四甲基环戊二烯基)四甲基二硅烷与正丁基锂作用生成(四甲基二硅撑)双(四甲基环戊二烯基负离子盐),后者随即与六碳基钼反应形成1,1'-(四甲基二硅撑)双(四甲基环戊二烯基铝负离子盐)-(Me₂SiSiMe₂)[Me₄CpMo(CO)₃-Li⁺]₂(I),I与冰醋酸作用,随即分别与CCl₄,NBS及I₂反应,生成相应的铝卤化合物(Me₂SiSiMe₂)[Me₄CpMo(CO)₃X]₂[X=Cl(1),Br(2),I(3)].I与CH₃I反应,在钼原子上发生烃基化,得到产物(Me₂SiSiMe₂)[Me₄CpMo(CO)₃Me]₂(4);I与单质I₂直接反应,生成脱硅桥产物Me₄Cp(CO)>₃I(5).经元素分析、IR及¹HNMR表征了化合物1-5的结构。     

Two New Cyclic Peptides from Psammosilene tunicoides

PsammosilenetunicoidesW.C.WuetC.YWu,amonotypegenusplantbelongingtoCaryophyllaceae,isafamousmedicinalherbinYunnanprovince.Itisusedasanodyneandhaemastaticagent1.Studiesonitssaponinshavebeenreported2-4.Asapartofourinvestigationonthenewbioactivecyclopeptidesfromhigherplants'-",thechromatographicpurificationoftheacetone-solublefractionofthedriedrootsofthetitleplant(25Kg)ledtotheisolationoftwonewcyclicoctapeptides,psammosileninsA(10mg)andB(6mg).Thispaperdealswiththeelucidationoftheirstructures.…     

Two new cyclopeptides from stellaria yunnanensis

In the previous papers, we reported the isolation and structural elucidation of three new cyclopeptides, namely stellarin A, B and C, from the fresh roots of stellaria yunnanensis Franch. In a continued study on this plant, other two new cyclopeptides named stellarin D(1) and E(2) were obtained and their structures were established to be cyclo (Gly-Tyr-Leu-Phe-Pro-Ile-Pro)(1), cyclo(Gly-Ile-Pro-Tyr-Ile-Ala-Ala)(2), respectively.     

Longicalycinin A, a new cytotoxic cyclic peptide from Dianthus superbus var. longicalycinus (MAXIM.) WILL

A new cyclic peptide, longicalycinin A (1), and six known compounds, vaccaroside A, dianoside A, dianoside G, 3-(4-hydroxy-3-methoxy-phenyl)propionic acid methyl ester, p-hydroxybenzoic acid, and p-hydroxybenzaldehyde were isolated from the MeOH extract of Dianthus superbus var. longicalycinus. The amino acid sequences of 1 was elucidated as cyclo(Gly(1)-Phe(2)-Tyr(3)-Pro(4)-Phe(5)-) on the basis of ESI tandem mass fragmentation analysis, chemical evidence, and extensive 2D NMR methods. Furthermore, compound 1 showed cytotoxicity to Hep G2 cancer cell line.     

A New Cyclic Peptide from Schnabelia tetradonta

A new cyclic octapeptide (schnabepeptide B) was isolated from the aerial part of Schnabelia tetradonta (Sun) C. Y. Wu et C. Chert (Lamiaceae). Its structure was elucidated as cyclo-(NH-Trp-Gly1-Leu1-Gly2-Pro1-Pro2-Leu2-Pr03-CO) on the basis of extensive 2D NMR and MS spectra.     

Stellarins F and G, two new cyclopeptides from Stellaria yunnanensis

In the previous papers,we reported the structural elucidation of stellarins A-E,fivenew cyclopeptides from the fresh roots of Stellaria yunnanensis Franch.Further chemical study on this plant led to the isolation of two other new cyclopeptides named stellarins F(l) and G(2).By a combination of 2D-NMR,enzymatic degradation and FABMS,their structures were established to be cyclo(Gly-Ala-Gly-Ser-Pro-Trp-Phe-Pro) and cyclo(Gly-Ala-Tyr-Leu-Ala),respectively.     

Two New Cyclopeptides from Arenaria oreophila (Caryophyllaceae)

Two new cyclopeptides, named arenariphilin A ( 1 ) and arenariphilin B ( 2 ), were isolated from the whole plants of Arenaria oreophila. Their structures were determined as cyclo‐(Thr‐Gly) ( 1 ) and cyclo‐(Ser₁‐Gly ‐Ser₂‐Ile ‐Phe₁‐Phe₂) ( 2 ) on the basis of spectral data, especially by 2D‐NMR.     

Cyclopeptides and Amides from Pseudostellaria heterophylla (Caryophyllaceae)

From the roots of Pseudostellaria heterophylla, three cyclopeptides and three amides were isolated, besides heterophyllin A and B. Their structures were determined as cyclo (Ala‐Gly‐Pro‐Val‐Tyr‐) (heterophyllin J; 1 ), cyclo (Ala‐Gly‐Pro‐Tyr‐Leu‐) (pseudostellarin A; 2 ), cyclo (Gly‐Gly‐Gly‐Pro‐Pro‐Phe‐Gly‐Ile‐) (pseudostellarin B; 3 ), methyl γ‐hydroxypyroglutamate ( 4 ), methyl pyroglutamate ( 5 ), and pyroglutamic acid ( 6 ) on the basis of spectral data, especially 2D‐NMR data. Among them, compounds 1 and 4 are new compounds.     

Intramolecular Transfer of Excitation Energy,Complexation with Metal Ions,and Interactions with Liposomes of Cyclo [tryptophyl-sarcosyl-sarcosyl-Nϵ-dansyllysyl-prolyl]

A cyclic pentapeptide containing an energy donor group and an energy acceptor group within the molecule, cyclo [Trp-Sar-Sar-Lys (DNS)-Pro], was synthesized. Its conformation, complexation with metal ions, intramolecular energy transfer, and interaction with liposomes were investigated. The precursor, cyclo [Trp-Sar-Sar Lys ( Z )-Pro], contained one cis-sarcosyl peptide bond and a β-turn in which the Pro-residue occupied the 3rd position. This cyclic pentapeptide formed a complex selectively with Ba²⁺ and its binding constant in 95% aqueous methanol solution was 2.0 × 10³ 1 · mol^?1. The intramolecular energy-transfer efficiency of cyclo [Trp-Sar-Sar-Lys (DNS)-Pro] was almost constant between ? 60° and 40° in ethanol, while it increased at temperatures lower than 34° in liposomes as a result of the pre-transition of the lipid assembly. On the other hand, the intramolecular energy transfer efficiency of cyclo [Trp-Sar-Sar-Lys (DNS)-Pro] decreased upon complexation with Ba²⁺.     

Gaseous bradykinin and its singly, doubly, and triply protonated forms: a first-principles study

The conformers of gaseous bradykinin, BK, (Arg(1)-Pro(2)-Pro(3)-Gly(4)-Phe(5)-Ser(6)-Pro(7)-Phe(8)-Arg(9)) and its protonated forms, [BK + H](+), [BK + 2H](2+), and [BK + 3H](3+), were examined theoretically using a combination of the Merck molecular force field, Hartree-Fock, and density functional theory. Neutral BK, [BK + H](+), and [BK + 2H](2+) exist in zwitterionic forms that are stabilized by internal solvation and have compact structures; [BK + 3H](3+) differs by the absence of a salt bridge and adopts an elongated form. The common structural feature in all four BK species is a beta-turn in the Ser(6)-Pro(7)-Phe(8)-Arg(9) sequence. The gas-phase basicity of [BK + H](+) estimated from the calculated protonation energy is in accord with published experimental basicity; population-weighted collision cross-sections of the three ionic forms are in agreement with experimental cross-sections in the literature.     

Synthesis of novel fatty-acyl gratisin derivatives

To find candidates with high antimicrobial and low hemolytic activities, many gratisin (GR) analogues have been designed and synthesized. In the present account, we synthesized novel derivatives of GR having both the polycationic and fatty acyl groups, cyclo{-Val(1)-Orn(2)-Leu(3)-D-Phe(4)-Pro(5)-D-Lys(6)(X)-Val(7)-Orn(8)-Leu(9)-D-Phe(10)-Pro(11)-D-Lys(12)-} {X=-CO(CH(2))(6)CH(3) (1), -Lys-CO(CH(2))(6)CH(3) (2), -(Lys)(2)-CO(CH(2))(6)CH(3) (3), and -(Lys)(3)-CO(CH(2))(6)CH(3) (4)}, and examined the biological activities. Among them, we found that 2-4 have differential ionic interaction against the prokaryotic membrane and eukaryotic membrane. In other words, the dissociation with high antimicrobial activity and low hemolytic activity is caused by the addition of D-Lys(6)-{(Lys)(n)-CO(CH(2))(6)CH(3)} residues at position 6 of [D-Lys(6,12)]-GR. Our findings should be helpful in finding drug candidates with high antimicrobial activity and low hemolytic activity that are capable of combating microbial resistance.