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71.
Cheng-Ting Zi Liu Yang Fa-Wu Dong Qing-Hua Kong Zhong-Tao Ding Jun Zhou 《Natural product research》2020,34(16):2301-2309
Abstract Two new compounds (9 and 10) having a camptothecin (CPT) analog conjugated to the 4β-azido-4-deoxypodophyllotixin analog by untilizing the copper-catalyzed azide-alkyne cycloadditon (CuAAC) reaction, and were evaluated for their cytotoxicity against a panel of five human cancer cell lines (HL-60, SMMC-7721, A-549, MCF-7 and SW480) using the MTT (3-(4,5-dimethyl-thiahiazo-2-yl)-2,5-diphenyltetrazolium bromide) assay. Two novel conjugates shown weak cytotoxicity, compound 10 showed highly potent against HL-60 cell line tested, with IC50 value 17.69?±?0.19?μM. This compound suggested its potential as anticancer agents for further development. 相似文献
72.
73.
高立体选择性地合成β-甘露糖苷和β-氨基甘露糖苷是糖化学家所面临的富有挑战性的问题。本文综述了合成β-甘露糖苷和β-氨基甘露糖苷的方法,侧重讨论各种方法在构建β-糖苷键时所具有的优势及其应用。 相似文献
74.
白卡奴鸽动脉粥样硬化模型微量元素谱的计算机多元分析 总被引:1,自引:0,他引:1
用ICP-AES测定了白卡奴鸽动脉粥样硬化模型和对照组的器官和组织中19种元素含量,通过因子分析,取得一系列因子得分图,结果表明,动脉粥样硬化和对照组样品点分布在不同区域,且可分辨。 相似文献
75.
76.
We have performed Langevin dynamics and Poisson-Nernst-Planck calculations to simulate detection of proteins by genetically engineered alpha-hemolysin channels. In the recent stochastic sensing experiments, one end of a flexible polymer chain is permanently anchored inside the protein channel at a specified location, and the other end undergoes complexation with an analyte. Our simulations, using coarse-grained modeling, reproduce all essential qualitative results of the electrophysiology measurements of stochastic sensing. In addition, the underlying macromolecular mechanisms behind stochastic sensing are revealed in vivid details. The entropic fluctuations of the conformations of the tethered polymer chain dictate crucially the unique signatures of the ionic current trace of the channel and provide design rules for successful stochastic sensing. The origin of strong fluctuations in the ionic current of the channel is found to arise from the obstruction of the entrance at the beta-barrel of the channel by the fluctuating segments of the tether. Silencing of the pore is due to the suppression of conformational fluctuations of the chain, and the permanent blockade of ionic current is due to the threading of the tether through the channel. The onset of silencing and permanent blockade of the channel current cannot necessarily be attributed to the capture of analytes. In order for detection events to be timed accurately, the length and anchoring location of the tether must be tuned appropriately. 相似文献
77.
Xiao-Xiang Li Jun-Wen Wang Yu-Jing Guo Ling-Hong Kong Jing-Hao Pan 《Journal of inclusion phenomena and macrocyclic chemistry》2007,58(3-4):307-315
In phosphate buffer solution of pH5.4, the interaction of meso-tetrakis(2-thienyl)porphyrin(H2TTP) and Cu-meso-tetrakis(2-thienyl)porphyrin(Cu-TTP) with α-cyclodextrin(α-CD), β-CD, γ-CD, heptakis(2,3,6-tri-O-methyl)-β-CD(TM-β-CD)
has been studied by means of UV-vis, fluorescence and 1HNMR spectroscopy, respectively. The H2TTP and Cu-TTP can form 1:2 inclusion complexes with TM-β-CD and 1:1 inclusion complexes with the other three cyclodextrins.
In this paper, the inclusion constants (K) of H2TTP and Cu-TTP for the formation of the inclusion complexes have been estimated from the changes of absorbance and fluorescence
intensity in phosphate buffer solution. The inclusive capabilities of different kinds of cyclodextrins are compared. The result
shows that the inclusion ability of α-CD with H2TTP and Cu-TTP is the strongest among the three native CDs. The inclusion ability of modified β-CD with H2TTP and Cu-TTP is stronger, compared to the native β-CD, which indicates that the capacity matching plays a crucial role in
the inclusion procedure except for the hydrophobic effect. In addition 1HNMR spectra supports the inclusion conformation of the TM-β-CD-Cu-TTP inclusion complex, indicating the interaction mechanism
of inclusion processes. 相似文献
78.
79.
实验光谱学和理论计算都发现,“重原子”能隔离分子中的某些振动能景,如SiH_4中Si—H振动泛频的“局域模”.Roger 等在研究F 原子与M(CH_2CH=CH_2)_4(M=Sn,Ge)的反应中,发现了Sn,Ge 对过剩能量转移到其它部分有强烈的阻碍作用(在中间态的寿命时间内).最近,在研究O(~1D)+M(CH_3)_4生成OH(v)反应中,观测到类似的现象.M=C 时,Lutz 用激光诱导荧光方法检测OH 的振动分布,振动是冷的,v=1与v=0的布居比为0.05, 相似文献
80.
Hu Yang Weisi Yin Xuxin Kong Min Xu Yefeng Yao Qun Chen Rongshi Cheng 《Colloid and polymer science》2006,284(8):935-940
The compact single-chain (SC) particulates of Poly(N-isopropylacrylamide) (PNIPAM), which have been formed above its lower critical solution temperature in an aqueous solution containing the surfactant of sodium n-dodecyl sulfate (SDS), were recovered from the solution by freeze-drying. Under scanning electron microscopy, the compact particulate appears as a spherical or elliptical particulate individually dispersed in SDS, which acts as a solid solvent to prevent agglomeration. The conformation of the compact SC particulates of PNIPAM dispersed in SDS had been studied by the solid-state high-resolution 13C NMR spectroscopy. The 13C spin-lattice relaxation time T
1 of the SC sample was determined in comparison with that of the original one. It was found that the T
1 of the methyl carbon in the isopropyl group of the SC sample was about 45% higher than that in the original multichain sample, which revealed the differences in the motion of the methyl group in the different condensed states and illuminated the characteristic conformation of the compact SC globular particulates of PNIPAM. 相似文献