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991.
The secondary metabolites of different Ephedra plants are various. Therefore, the discrimination of different Ephedra plants is significant. An objective, easy-to-use, rapid and pollution-free approach is proposed for discriminating Ephedra plants of different species, habitats and picking times on the basis of diffuse reflectance Fourier transform near infrared spectroscopy (FT-NIRS) measurements and multivariate analysis. The Fourier transform near infrared diffuse reflectance spectra (NIRDRS) were acquired from 37 pulverized samples of Ephedra plants put in glass vials in the near infrared (NIR) region between 10 000 and 4000 cm−1, averaging 64 scans per spectrum at a resolution of 4 cm−1. After spectra processing and data pre-processing, spectral data were analyzed respectively with three multivariate analysis techniques: discriminant analysis (DA), self-organizing map (SOM) and back-propagation artificial neural network (BP-ANN). The proposed method could distinguish not only the Ephedra plants of three species and two habitats but also the plants picked at different times of day without special sample treatment and the use of chemical reagents. The performance indexes of the DA model were 84.2-91.9% and the prediction accuracies of both the SOM and the BP-ANN models reached 93.3-100.0%. 相似文献
992.
Three new caged prenylxanthones (xanthone=9H‐xanthen‐9‐one), named neobractatin ( 1 ), 3‐O‐methylneobractatin ( 2 ), and 3‐O‐methylbractatin ( 3 ), along with eight known compounds, were isolated from the twig of Garcinia bracteata. The structures of the new compounds were elucidated on the basis of 1D‐ and 2D‐NMR experiments, including HMBC, HSQC, 1H,1H‐COSY, and ROESY, as well as HR‐MS analysis. 相似文献
993.
Xiangli Liu Ping Fan Ming Chen Hossam Hefesha GerhardK.E. Scriba Detlef Gabel Alfred Fahr 《Helvetica chimica acta》2010,93(2):203-211
The objective of this study was to investigate drug–membrane interaction by immobilized liposome chromatography (ILC; expressed as lipophilicity index log Ks) and the comparison with lipophilicity indices obtained by liposome/H2O, octan‐1‐ol/H2O, and immobilized artificial membrane (IAM) systems. A set of structurally diverse monofunctional compounds and drugs (nonsteroidal anti‐inflammatory drugs and β‐blockers) were selected in this study. This set of solutes consists of basic or acidic functionalities which are positively or negatively charged at physiological pH 7.4. No correlation was found between log Ks from ILC and lipophilicity indices from any of the other membrane model systems for the whole set of compounds. For structurally related compounds, significant correlations could be established between log Ks from ILC and lipophilicity indices from IAM chromatography and octan‐1‐ol/H2O. However, ILC and liposome/H2O systems only yield parallel partitioning information for structurally related large molecules. For hydrophilic compounds, the balance between electrostatic and hydrophobic interactions dominating drug partitioning is different in these two systems. 相似文献
994.
A new 3d–4f heterometallic coordination framework, {[Eu(ox)(H2O)4] · [CuBr(2‐pzc)2] · 4H2O} ( 1 ) [ox = oxalate; 2‐pzc = pyrazine‐2‐carboxylate] was synthesized and characterized by elemental analysis, IR spectroscopy and thermal analysis, as well as single‐crystal X‐ray diffraction. Complex 1 represents one 3D supramolecular heterometallic coordination framework that is assembled from rare lanthanide‐ox anionic chains and CuBr(2‐pzc)2 cationic units through hydrogen bonds. 相似文献
995.
Yanyan Qiu Hai Fan Xu Liu Shiyun Ai Tiantian Tang Ruixia Han 《Mikrochimica acta》2010,171(3-4):363-369
A glassy carbon electrode was modified with dsDNA and a nanocomposite composed of multi-walled carbon nanotubes and chitosan (MWNT-chit). The electrode was applied to the electrochemical detection of DNA damage as induced by in situ generated bisphenol A (BPA) radicals through electro-oxidation. The modified electrode was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The results indicate that MWNT-chit nanocomposite represents a viable platform for the immobilization of DNA that effectively promotes electron transfer between DNA and the electrode. The mode of interaction between DNA and BPA was investigated by differential pulse voltammetry and UV-vis spectrophotometry, indicating that the dominant interaction is intercalation. In order to explore the mechanism of damage caused by BPA radicals, the electro-oxidation of BPA at the modified glass electrode was investigated. Based on the signal for guanine without any other external indicator, DNA damage was investigated through the electro-oxidation of BPA. 相似文献
996.
Quantum dot capped magnetite nanorings as high performance nanoprobe for multiphoton fluorescence and magnetic resonance imaging 总被引:1,自引:0,他引:1
Fan HM Olivo M Shuter B Yi JB Bhuvaneswari R Tan HR Xing GC Ng CT Liu L Lucky SS Bay BH Ding J 《Journal of the American Chemical Society》2010,132(42):14803-14811
In the present study, quantum dot (QD) capped magnetite nanorings (NRs) with a high luminescence and magnetic vortex core have been successfully developed as a new class of magnetic-fluorescent nanoprobe. Through electrostatic interaction, cationic polyethylenimine (PEI) capped QD have been firmly graft into negatively charged magnetite NRs modified with citric acid on the surface. The obtained biocompatible multicolor QD capped magnetite NRs exhibit a much stronger magnetic resonance (MR) T2* effect where the r2* relaxivity and r2*/r1 ratio are 4 times and 110 times respectively larger than those of a commercial superparamagnetic iron oxide. The multiphoton fluorescence imaging and cell uptake of QD capped magnetite NRs are also demonstrated using MGH bladder cancer cells. In particular, these QD capped magnetite NRs can escape from endosomes and be released into the cytoplasm. The obtained results from these exploratory experiments suggest that the cell-penetrating QD capped magnetite NRs could be an excellent dual-modality nanoprobe for intracellular imaging and therapeutic applications. This work has shown great potential of the magnetic vortex core based multifunctional nanoparticle as a high performance nanoprobe for biomedical applications. 相似文献
997.
A series of novel helicid derivatives containing 3,4-dihydropyrimidin-2(1H)-one and 3,4-dihydropyrimidine2(1H)-thione moiety (3a–3f and 4a–4f) were synthesized starting from helicid. The structure of the new compounds were characterized by 1H NMR, IR and HR-MS spectra. The sedative-hypnotic activities of the target compounds were evaluated using the test of spontaneous
locomotor activity in mice. All of the derivatives produced moderate to high activities; in particular, compound 4a presented the most potent sedative-hypnotic effect in comparison to the other derivatives, and derivatives 3a, 3c, 3d, 3e and 3f also showed potent activities. 相似文献
998.
Wei Wei Shuyue Fan Fengqing Wang Dongzhi Wei 《Applied biochemistry and biotechnology》2010,162(5):1446-1456
Using enrichment procedures, five strains that can utilize soybean phytosterols as the sole carbon source were isolated from
steroids-contaminated soil samples. Among the isolated strains, the strain NwIB-01 with the highest steroid degradation ability
was identified as Mycobacterium neoaurum by morphological, physiological, biochemical tests and 16S rRNA sequence analysis. Meanwhile, the key enzyme gene, which
was involved in steroid metabolism and encoding 395-amino acid 3-ketosteroid 9α-hydroxylase (KSH), was obtained from M. neoaurum NwIB-01 with the assistance of homology analysis and chromosome walking. To our best knowledge, this is the first report
to the gene of key enzyme KSH from M. neoaurum. Strain NwIB-01 exhibited powerful ability of cleaving the side chain specifically from soybean phytosterols to accumulate
4-androstene-3,17-dione (AD) and 1,4-androstadiene-3,17-dione (ADD). It was showed that when cultured in 15 g/l phytosterols,
the yield of ADD reached 4.23 g/l while accompanied by 1.76 g/l AD in 96-h-old culture (the molar yield of AD + ADD is 64.7%).
The strain NwIB-01 can be applied as excellent phytosterols-transformation strains in potential industrial applications. 相似文献
999.
Qiang Wang Guibiao Jin Xuerong Fan Xianfei Zhao Li Cui Ping Wang 《Applied biochemistry and biotechnology》2010,160(8):2486-2497
ε-Poly-l-lysine (ε-PL), a natural biomacromolecule having a broad spectrum of antibacterial activity, was grafted on the wool fiber
via the acyl transfer reaction catalyzed by microbial transglutaminase (mTGase) to develop a new strategy for antibacterial
functionalization of proteinous materials. The effects of the concentrations of ε-PLs and mTGases on the graft yields were
investigated. A coating of ε-PL that almost completely covered the scale profile on the wool surface was visualized by scanning
electron microscopy (SEM) and further demonstrated in terms of Allw?rden’s reaction characteristic of wool. Identifiable differences
in lysine content and color depth among the stained wool samples reveal the changes in the surface composition and polarity
caused by the incorporation of ε-PL onto the wool substrate, respectively. The ratio of bacteriostasis to Escherichia coli of the wool fabric grafting ε-PL reached 96.6 %, indicating an excellent antibacterial effect. The application of ε-PL and
corresponding mTGase-catalyzed grafting reaction would provide a worthwhile reference for antibacterial functionalization
of proteinous materials in various forms. 相似文献
1000.
A DNA fragment containing the entire coding sequence of nitrilase gene was amplified from Rhodococcus rhodochrous tg1-A6 with high nitrilase activity using PCR and sequenced. The open reading frame of the nitrilase gene contains 1,101 base
pairs, which encodes a putative polypeptide of 366 amino acid residues. The nitrilase gene was cloned into an expression vector
pET-28a and expressed in an Escherichia coli strain BL21(DE3). The enzymatic activity of nitrilase, which converts various nitriles to the corresponding carboxylic acids,
was detected to reach 24.5 U/ml at 9 h in the recombinant bacteria. 相似文献