藤三七中一个新黄烷醇和抗HIV活性成分

利用各种色谱(硅胶和凝胶)方法,从藤三七[Boussingaultia gracilis Miers var.pseudobaselloides Bailey]的70%(体积分数)的乙醇提取物中分离得到2个黄烷醇类化合物(1,2)和4个黄酮类化合物(3～6).采用UV,IR,MS 和1D,2D NMR方法,分别鉴定出如下化合物: 7-羟基-5-甲氧基-8-甲基-6-甲酰基-3,4-黄烷二醇,命名为藤三七醇A(1);4,7-二羟基-5-甲氧基-8-甲基-6-甲酰基黄烷(2);7-O-methylunonal(3);5,7-二羟基-6,8-二甲基-2-苯基-4H-1-苯并吡喃-4-酮(4);Desmosflavone(5)和Demethoxymatteucinol(6).其中化合物1是一个新的黄烷二醇化合物,化合物2～6为首次从该植物中分离得到.抗HIV-1活性筛选结果表明: 化合物1,2,5,6对HIV-1诱导合胞体的形成具有一定的抑制作用,其半数有效浓度(EC50)分别为45.09,48.73,55.47 和 82.75 μmol/L,治疗指数(TI)分别为1.41,1.20,7.15 和》8.51.

Dibenzocyclooctadiene Lignans from Schisandra wilsoniana and Their Anti-HIV-1 Activities

Twelve new dibenzocyclooctadiene lignans, marlignans A-L (1-12), together with 16 known compounds, were isolated from the leaves and stems of Schisandra wilsoniana. The structures of 1-12 were elucidated by spectroscopic methods including 1D- and 2D-NMR techniques. Compounds 1-12 were evaluated for their anti-HIV activities, of which compounds 3, 6, 8, and 12 showed modest activities with therapeutic index values of 13.2, 15.6, 17.6, and 16.4, respectively.

Anti-HIV-1 Activity of Lignans from the Fruits of Schisandra rubriflora

This study investigated the 70% aqueous acetone extract of the fruits of Schisandra rubriflora which led to the isolation of eight lignans, including a new isolate, rubrisandrin C (1), and seven known lignans (2-8). The structure of 1 was established by extensive 1D and 2D NMR spectroscopy and its absolute stereochemistry was determined by CD spectrum. Compounds 1-5 and 7-8 were evaluated for their anti-HIV-1 activity that showed inhibitory activity on HIV-1(IIIB) induced syncytium formation with EC50 values in the range of 2.26 similar to 20.4 mu g/mL. Compounds 1 and 7 exerted their obvious protection of HIV-1(IIIB) inducted MT-4 host cells lytic effects with a selectivity index of 15.4 and 24.6, respectively.

Anti-HIV Actions of 7- and 10-Substituted Camptothecins (vol 15, pg 138, 2010)

The authors thank the anonymous reviewer for helpful comments on the early version of the manuscript. This work was financially supported by the earmarked fund for Modern Agro-industry Technology Research System, the Science Fund for Young Scholars in Sichuan Province (Grant No: ZQ 026-017), and the National 863 Project of China (No. 2008AA101001).

Neurochemical changes in brain induced by chronic morphine treatment: NMR studies in thalamus and somatosensory cortex of rats

To investigate the effects of chronic morphine treatment and its cessation on thalamus and the somatosensory cortex, an ex vivo high resolution (500 MHz) H-1 nuclear magnetic resonance spectroscopy (NMRS), in the present study, was applied to detect multi

Metabolic changes in rat prefrontal cortex and hippocampus induced by chronic morphine treatment studied ex vivo by high resolution H-1 NMR spectroscopy

Ex vivo H-1 NMR spectroscopy was used to measure changes in the concentrations of cerebral metabolites in the prefrontal cortex (PFC) and hippocampus of rats subjected to repeated morphine treatment known to cause tolerance/dependence. The results show th

Structure-function relationship of three neurotoxins from the venom of Naja kaouthia: a comparison between the NMR-derived structure of NT2 with its homologues, NT1 and NT3

Three homologous short-chain neurotoxins, named NT1, NT2 and NT3, were purified from the venom of Naja kaouthia. NT1 has an identical amino acid sequence to cobrotoxin from Naja naja atra [Biochemistry 32 (1993) 2131]. NT3 shares the same sequence with cobrotoxin b [J. Biochem. (Tokyo) 122 (1997) 1252], whereas NT2 is a novel 6 1 -residue neurotoxin. Tests of their physiological functions indicate that NT1 shows a greater inhibition of muscle contraction induced by electrical stimulation of the nerve than do NT2 and NT3. Homonuclear proton two-dimensional NMR methods were utilized to study the solution tertiary structure of NT2. A homology model-building method was employed to predict the structure of NT3. Comparison of the structures of these three toxins shows that the surface conformation of NT1 facilitates the substituted base residues, Arg28, Arg30, and Arg36, to occupy the favorable spatial location in the central region of loop 11, and the cation groups of all three arginines face out of the molecular surface of NT1 This may contribute greatly to the higher binding of NT1 with AchR compared to NT2 and NT3. (C) 2002 Elsevier Science B,V. All rights reserved.

Bayesian inference for multidimensional NMR image reconstruction

Reconstruction of an image from a set of projections has been adapted to generate multidimensional nuclear magnetic resonance (NMR) spectra, which have discrete features that are relatively sparsely distributed in space. For this reason, a reliable reconstruction can be made from a small number of projections. This new concept is called Projection Reconstruction NMR (PR-NMR). In this paper, multidimensional NMR spectra are reconstructed by Reversible Jump Markov Chain Monte Carlo (RJMCMC). This statistical method generates samples under the assumption that each peak consists of a small number of parameters: position of peak centres, peak amplitude, and peak width. In order to find the number of peaks and shape, RJMCMC has several moves: birth, death, merge, split, and invariant updating. The reconstruction schemes are tested on a set of six projections derived from the three-dimensional 700 MHz HNCO spectrum of a protein HasA.

用NMR确定MCYST-LR环肽部分的结构

利用一维和二维核磁共振技术对从鱼塘水华样品中提取的一种毒素进行了研究 ,结合其它分析手段 ,确定了该毒素即为普通环七肽肝毒素Microcystin LR (MCYST LR) ,测定了该环七肽的环上氨基酸残基的连接方式和顺序 .

~(59)Co~(2+)对~1H与~(35)Cl的NMR影响

<正> 在前文的基础上,用~(59)CO~2+Cl_2·6H_2O加D_2O作为样品,在200MHz谱仪上观察~1H,在400MHz谱仪上观察~(35)Cl,研究强顺磁离子~(59)Co~2+(s=3/2,I=7/2)在外加直流磁场H_0作用下,它对~1H与~(35)Cl的NMR影响。因为强顺磁离子~(59)Co~(2+)的电子自旋(s=3/2)是围绕着核旋转的,因此可以统计平均计算,

Revealing lithium-silicide phase transformations in nano-structured silicon-based lithium ion batteries via in situ NMR spectroscopy.

Nano-structured silicon anodes are attractive alternatives to graphitic carbons in rechargeable Li-ion batteries, owing to their extremely high capacities. Despite their advantages, numerous issues remain to be addressed, the most basic being to understand the complex kinetics and thermodynamics that control the reactions and structural rearrangements. Elucidating this necessitates real-time in situ metrologies, which are highly challenging, if the whole electrode structure is studied at an atomistic level for multiple cycles under realistic cycling conditions. Here we report that Si nanowires grown on a conducting carbon-fibre support provide a robust model battery system that can be studied by (7)Li in situ NMR spectroscopy. The method allows the (de)alloying reactions of the amorphous silicides to be followed in the 2nd cycle and beyond. In combination with density-functional theory calculations, the results provide insight into the amorphous and amorphous-to-crystalline lithium-silicide transformations, particularly those at low voltages, which are highly relevant to practical cycling strategies.

Relationships among the contents of total phenolics, soluble carbohydrate, and free amino acids of 15 aquatic macrophytes

In order to examine how carbon and nitrogen status of a macrophyte may affect its total phenolics (TP) production, the contents of free amino acids (FAA), soluble carbohydrate (SC) and TP were examined in leaves of seven submersed, four floating-leaved, and four emergent macrophytes. The floating-leaved and emergent macrophytes had much higher contents of SC and TP than the submersed macrophytes. The contents of FAA were not significantly different among the submersed, floating-leaved, and emergent macrophytes. Correlations among the contents of FAA, SC, and TP indicated that the production of TP was more dependent on the SC content than on the FAA content.

Identification of a gene, ccr-1 (sll1242), required for chill-light tolerance and growth at 15 degrees C in Synechocystis sp PCC 6803

Synechocystis sp. PCC 6803 exposed to chill (5 degrees C)-light (100 mu mol photons m(-2) s(-1)) stress loses its ability to reinitiate growth. From a random insertion mutant library of Synechocystis sp. PCC 6803, a sll1242 mutant showing increased sensitivity to chill plus light was isolated. Mutant reconstruction and complementation with the wild-type gene confirmed the role of sll1242 in maintaining chill-light tolerance. At 15 degrees C, the autotrophic and mixotrophic growth of the mutant were both inhibited, paralleled by decreased photosynthetic activity. The expression of sll1242 was upregulated in Synechocystis sp. PCC 6803 after transfer from 30 to 15 degrees C at a photosynthetic photon flux density of 30 mu mol photons m(-2) S-1. sll1242, named ccr (cyanobacterial cold resistance gene)- 1, may be required for cold acclimation of cyanobacteria in light.