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711.
In this study, a RP-HPLC method for the analysis of polyacetylenes and polyenes in Echinacea pallida roots and phytopharmaceuticals was developed. The reference compounds used for quantification were isolated from the plant material and their structures were determined on the basis of the analysis of UV, IR, NMR and MS data. The complete structure elucidation of three compounds, namely 8-hydroxy-tetradec-(9E)-ene-11,13-diyn-2-one (1), tetradec-(8Z)-ene-11,13-diyn-2-one (6) and pentadec-(8Z)-en-2-one (9) is described. In the analysis of the n-hexane extracts of E. pallida roots, the comparison between conventional and monolithic columns showed that the elution order in both cases is identical and the selectivity is equivalent. However, the retention times achieved by the monolithic column are shorter, resulting in a faster separation (20 min). Therefore, the analyses were carried out on a Chromolith Performance RP-18e (100 mm x 4.6 mm i.d.), with a gradient mobile phase composed by H(2)O and ACN at the flow rate of 2 mL/min. The column was thermostatted at 20 degrees C. The photodiode array detector monitored the eluent at 210 nm. The validation procedure confirmed that this technique affords reliable analysis of these components and is appropriate for the quality control of complex matrices, such as E. pallida roots and phytopharmaceuticals. 相似文献
712.
Di Giambattista L Pozzi D Grimaldi P Gaudenzi S Morrone S Castellano AC 《Analytical and bioanalytical chemistry》2011,399(8):2771-2778
Fourier transform infrared spectroscopy in attenuated total reflection can be used to discriminate the necrotic from the apoptotic
cell death in a tumoral T cell line irradiated by a UV source able to induce both apoptosis and necrosis. Using Jurkat cells
as the model system, significant spectral differences in the irradiated cells vs. time were observed in the lipid–proteins
ratio absorbance band at 1,397 cm−1 and in lactic acid IR band at 1,122 cm−1; these spectral features are inversely correlated with the percentage of apoptotic cells assessed by flow cytometry. From
the analysis of second derivatives in the IR spectral region between 1,800 and 900 cm−1, we have detected two significant spectral changes: the first centered at 1,621 cm−1 by analyzing the components of the amide I band and the second centered at 1,069 cm−1 due to C–O stretching vibration of the DNA backbone sensitive to the dehydrated state of DNA; these identified differences
in the intracellular biomolecules have been allowed to monitor the necrotic process. The variations in the spectral data set
have been identified by the Kruskal–Wallis test and confirmed by the hierarchical cluster analysis. 相似文献
713.
Gemma S Colombo L Forloni G Savini L Fracasso C Caccia S Salmona M Brindisi M Joshi BP Tripaldi P Giorgi G Taglialatela-Scafati O Novellino E Fiorini I Campiani G Butini S 《Organic & biomolecular chemistry》2011,9(14):5137-5148
Here we describe the identification and preliminary characterization of a new class of pyrrolo(imidazo)quinoxaline hydrazones as florescent probes for Aβ(1-42) fibrils. All the newly developed compounds were able to bind amyloid fibrils formed in vitro and some of them displayed an increase of their fluorescence upon binding. When tested on brain tissue preparations presenting Aβ deposits, the described hydrazones selectively stained amyloid structures and did not display aspecific binding. The hydrazones did not show antifibrillogenic activity and electron microscopy analysis revealed that they do not interfere with fibrils structure. The described pyrrolo(imidazo)quinoxalines could be useful for studying amyloid structures in vitro. Moreover, their experimentally proven ability to cross the blood-brain barrier in mouse opens the possibility of developing these compounds as potential amyloid imaging agents for in vivo applications. 相似文献
714.
De Giglio E Trapani A Cafagna D Sabbatini L Cometa S 《Analytical and bioanalytical chemistry》2011,400(7):1997-2002
The formulation and characterization of dopamine (DA)-loaded chitosan nanoparticles (CSNPs) are described as preliminary steps
for the development of potential DA carrier systems intended for Parkinson’s disease treatment. For this purpose, CSNPs were
firstly produced and, afterwards, they were incubated in a DA aqueous solution to promote neurotransmitter loading. The characterization
of the resulting nanoparticles started with Fourier transform infrared spectroscopy analysis to ascertain the presence of
DA in the nanocarrier, whereas X-ray photoelectron spectroscopy analysis provided evidence of the localization of DA on the
nanoparticle surface. A quartz crystal microbalance with dissipation monitoring (QCM-D) was then exploited to investigate
both swelling of CSNPs and interaction of DA with CSNPs. In particular, the QCM-D revealed that this interaction is fast and
so this allows a stable nanostructured system to be obtained. 相似文献
715.
G. Cavallaro D. I. Donato G. Lazzara S. Milioto 《Journal of Thermal Analysis and Calorimetry》2011,104(2):451-457
Waterlogged archaeological woods Pinus pinaster and Fagus sylvatica L. were analyzed by using TG technique. Degradation processes ascribable to the holocellulose decay were evidenced at nearly
the same temperature for sound and archaeological samples. The residual matters at 600 and 900 °C of the sound woods are much
lower than those of archaeological waterlogged woods in agreement with the presence of inorganic materials encapsulated during
the burial into the marine environment. It was proposed a new protocol to rapidly calculate the maximum water content parameter,
which is related to the wood degradation state. TG experiments at variable heating rates were performed to obtain kinetic
parameters for the degradation process. The Flynn–Wall–Ozawa and Friedman approaches allowed us to calculate the activation
energy, which is significantly different for the sound and the archaeological woods. 相似文献
716.
Dr. Matteo Amelia Stefania Impellizzeri Simone Monaco Dr. Ibrahim Yildiz Dr. Serena Silvi Prof. Françisco M. Raymo Prof. Alberto Credi 《Chemphyschem》2011,12(12):2280-2288
Two series of CdSe quantum dots (QDs) with different diameters are prepared, according to frequently used protocols of the same synthetic procedure. For each sample the photophysical properties and the potentials for the first reduction and oxidation processes in organic solution are determined. The band gap obtained from electrochemical experiments is compared with that determined from the absorption and luminescence spectra. While the optical band gap decreases upon increasing the nanocrystal diameter, as expected on the basis of quantum confinement, the redox potentials and the electrochemical band gap are not monotonously related to the QD size. For both series, the smallest and largest QDs are both easier to oxidize and reduce than mid‐sized QDs. In fact, the latter samples exhibit very broad voltammetric profiles, which suggests that the heterogeneous electron‐transfer processes from/to the electrode are kinetically hindered. Conversely, the electrochemical band gap for the smallest and largest particles of each series is somewhat smaller than the optical band gap. These results indicate that, while the optical band gap depends on the actual electron–hole recombination within the nanocrystal, and therefore follows the size dependence expected from the particle‐in‐a‐box model, the electrochemical processes of these QDs are strongly affected by other factors, such as the presence of surface defects. The investigations suggest that the influence of these defects on the potential values is more important for the smallest and largest QDs of each series, as confirmed by the respective luminescence bands and quantum yields. An interpretation for the size‐dependent evolution of the surface defects in these nanocrystals is proposed based on the mechanism of their formation and growth. 相似文献
717.
Daniela Coppola Stefano Bruno Luca Ronda Cristiano Viappiani Stefania Abbruzzetti Guido di Prisco Cinzia Verde Andrea Mozzarelli 《BMC biochemistry》2011,12(1):1-8
Background
The majority of peroxisomal matrix proteins destined for translocation into the peroxisomal lumen are recognised via a C-terminal Peroxisomal Target Signal type 1 by the cycling receptor Pex5p. The only structure to date of Pex5p in complex with a cargo protein is that of the C-terminal cargo-binding domain of the receptor with sterol carrier protein 2, a small, model peroxisomal protein. In this study, we have tested the contribution of a second, ancillary receptor-cargo binding site, which was found in addition to the characterised Peroxisomal Target Signal type 1.Results
To investigate the function of this secondary interface we have mutated two key residues from the ancillary binding site and analyzed the level of binding first by a yeast-two-hybrid assay, followed by quantitative measurement of the binding affinity and kinetics of purified protein components and finally, by in vivo measurements, to determine translocation capability. While a moderate but significant reduction of the interaction was found in binding assays, we were not able to measure any significant defects in vivo.Conclusions
Our data therefore suggest that at least in the case of sterol carrier protein 2 the contribution of the second binding site is not essential for peroxisomal import. At this stage, however, we cannot rule out that other cargo proteins may require this ancillary binding site. 相似文献718.
The Diels-Alder (DA) and hetero-Diels-Alder (HDA) reaction of N-(2,4-dicyano-1,5-dimethyl-3-phenylcyclopenta-2,4-dienyl)-2,2,2-trifluoroacetamide 1 can be conveniently used for the synthesis of biarylic and polycyclic compounds, depending on whether you use alkynes or alkenes as dienophiles. We observe a totally regioselectivity and endo-diastereoselectivity of the cycloaddition reactions. 相似文献
719.
Grazia M.L. ConsoliViviana Cafiso Stefania StefaniCorrada Geraci 《Tetrahedron letters》2011,52(44):5831-5834
The first example of multivalent conjugate in which four α-l-C-fucosyl units are clustered by means of a calix[4]arene platform was designed as a new potential Pseudomonas aeruginosa biofilm inhibitor. The anti-biofilm activity of the synthesized compound (6) against PAO1 strain was assayed and it was found to be dose-dependent. The presence of the fucose cluster improves the biofilm inhibitor efficiency as proven by the lower inhibitor activity of the analogous glycyl-calix[4]arene derivative (3) lacking in the fucose moieties. 相似文献
720.
In this study, we investigated the heterogeneity and the purity grade of three commercially available plasma‐derived clotting factor VIII (FVIII) concentrates, which highly differ with regard to purification strategies, relative concentrations of stabilizers (von Willebrand factor, with or without albumin) and virus inactivation strategies (solvent/detergent and/or heat/pasteurization treatments). Western blot analyses were used to evaluate product‐specific variations from Emoclot®, Alphanate® and Haemate® both in the presence and absence of reducing agents (dithiotreithol). All the plasma‐derived concentrates showed a strong heterogeneity, as they all included a significant amount of truncated forms of the full‐length (FL) clotting FVIII protein. The intact protein accounted for the 38% of the total FVIII proteins in Haemate® and 29 and 23% in Alphanate® and Emoclot®, respectively. Lower intact FVIII amounts in Emoclot might be mainly due to the low von Willebrand factor dosage and the absence of albumin. Upon addition of thrombin, both the FL and truncated forms of the FVIII protein were almost completely digested. Indeed, after thrombin activation, we could still observe a mixture of B‐domain truncated forms of the FL protein along with biologically active digested‐A1 forms. Batch‐to‐batch variation was tested with no evident changes appearing among different batches. Despite the variables in manufacturing processes, inter‐product comparisons yielded similar results for all the plasma‐derived FVIII considered in this study. However, we could individuate in Emoclot a band that was not digested by thrombin, which we could characterize as the 200 kDa FVIII heavy chain. This investigation prompts new concerns about the strong heterogeneity observed upon thrombin digestion of plasma‐derived FVIII, which might contribute to the development of inhibitory antibodies at an early stage of therapy, and to which extent these untoward phenomena could be avoided through direct intervention on routine manufacturing processes. 相似文献