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S -nitrosothiols have many biological activities and may act as nitric oxide (NO) carriers and donors, prolonging NO half-life in vivo. In spite of their great potential as therapeutic agents, most S -nitrosothiols are too unstable to isolate. We have shown that the S -nitroso adduct of N -acetylcysteine (SNAC) can be synthesized directly in aqueous and polyethylene glycol (PEG) 400 matrix by using a reactive gaseous (NO/O2 ) mixture. Spectral monitoring of the S–N bond cleavage showed that SNAC, synthesized by this method, is relatively stable in nonbuf-fered aqueous solution at 25°C in the dark and that its stability is greatly increased in PEG matrix, resulting in a 28-fold decrease in its initial rate of thermal decomposition. Irradiation with UV light (λ= 333 nm) accelerated the rate of decomposition of SNAC to NO in both matrices, indicating that SNAC may find use for the photogeneration of NO. The quantum yield for SNAC decomposition decreased from 0.65 ± 0.15 in aqueous solution to 0.047 ± 0.005 in PEG 400 matrix. This increased stability in PEG matrix was assigned to a cage effect promoted by the PEG microenvironment that increases the rate of geminated radical pair recombination in the homolytic S–N bond cleavage process. This effect allowed for the storage of SNAC in PEG at −20°C in the dark for more than 10 weeks with negligible decomposition. Such stabilization may represent a viable option for the synthesis, storage and handling of S -nitrosothiol solutions for biomedical applications. 相似文献
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Giorgini E Conti C Ferraris P Sabbatini S Tosi G Rubini C Vaccari L Gioacchini G Carnevali O 《Analytical and bioanalytical chemistry》2010,398(7-8):3063-3072
The aim of this study was to verify the effects of probiotic Lactobacillus rhamnosus on zebrafish oocyte maturation using FPA (focal plane array) FTIR imaging together with specific biochemical assays (SDS-PAGE, real-time PCR and enzymatic assay). Oocyte growth is prevalently due to a vitellogenic process which consists of the hepatic synthesis of vitellogenin and its selective uptake during maturation. The administration of L. rhamnosus IMC 501 for 10 days induced chemical changes to oocyte composition, promoting the maturation process. Some interesting biochemical features, linked to protein secondary structure (amide I band) and to phospholipidic and glucidic patterns, were detailed by vibrational analysis. The spectroscopic results were supported by the early increase of the lysosomal enzyme involved in the final oocyte maturation, the cathepsin L. This enzyme increases during follicle maturation, with the highest levels in class IV oocytes. In treated females, class III oocytes showed higher cathepsin L gene expression and enzymatic activity, with levels comparable to class IV oocytes isolated from controls; this can be related to the proteolytic cleavage of the higher molecular mass yolk protein components, as evidenced by SDS-PAGE. 相似文献
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Tosi G Conti C Giorgini E Ferraris P Garavaglia MG Sabbatini S Staibano S Rubini C 《The Analyst》2010,135(12):3213-3219
Fourier transform infrared (FTIR) microspectroscopy has been employed to investigate benign (ordinary dermal and Reed nevi), dysplastic and malignant (invasive melanoma) skin lesions through the analysis of spectral changes of melanocytes as well as in the evaluation of the presence of melanin. Hierarchical cluster analysis and principal component analysis led to a satisfactory separation of malignant from dysplastic and normal melanocytes. Also, on enlarging the clustering with spectra from Reed and dermal nevi, the multivariate analysis segregated well the spectral data into discrete clusters, allowing the obtaining of reliable average spectra for analysis at the molecular level of the main groups or components responsible for the biological and biochemical changes. The most significant spectral characteristics appear to be related to differences in secondary protein structures, in nucleic acid conformation, in intra- and intermolecular bonding. In all cases, supervised and unsupervised spectral analyses resulted in satisfactory agreement with histopathological findings. 相似文献
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Gabriele Bocelli Andrea Cantoni Elisabetta Giorgini Giorgio Tosi 《Journal of chemical crystallography》1990,20(5):419-423
A series of complexes between 1-oxide quinolines and 7,7,8,8-tetracyanoquinodimethane has been synthesized and one of them has been analyzed by x-ray diffraction methods. Crystals of the title compound are monoclinic (C15H11NO·C12H4N4), space groupP21/n,a=44.525(4),b=7.326(2),c=6.531(2) Å,=90.23(3)°. The structure was solved by direct methods and refined by block-matrix least-squares to giveR=0.047 for 1865 reflections above 2(I). Molecular dimensions, interplanar distances, empirical method and IR spectra suggest a -* interaction with very low charge-transfer in the complex. 相似文献
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Sanchez-sanz M; Blyth MG 《The Quarterly Journal of Mechanics and Applied Mathematics》2007,60(2):125-138
Unsteady, axisymmetric stagnation flow about a circular cylinderis examined when the far-field flow is a periodic function oftime with a fixed time average and an oscillatory part of prescribedamplitude and frequency. Solutions are computed for arbitraryvalues of the Reynolds number, quantifying the effects of surfacecurvature, and a frequency parameter based on the period ofthe far-field flow. It is found that solutions remain regularand periodic provided that the far-field amplitude lies belowa critical value. Above this value, solutions terminate in afinite-time singularity. The blow-up time is delayed by increasingthe curvature of the surface. These results are corroboratedby asymptotic predictions valid in the limits of small and largeamplitude and frequency. For large Reynolds number, the problemreduces to the two-dimensional stagnation-point flow againsta plane wall studied by previous authors. 相似文献
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Nicola Monti Stefano Zacchini Massimiliano Massi Alejandro Hochkoeppler Loris Giorgini Valentina Fiorini Alessandra Stefan Stefano Stagni 《应用有机金属化学》2020,34(9):e5806
Herein, we describe a new family of tris chelate homoleptic Ru (II) complexes, [Ru(N^N) 3 ] 2+ , where the role of the diimine-type ligands (N^N) was fulfilled by 2-pyridyl (PTZ) or 2-quinolyl tetrazole (QTZ) derivatives decorated with various alkyl substituents at the N-2 position of the tetrazole ring. The new Ru (II) complexes with general formula [Ru (PTZ-R) 3 ] 2+ and [Ru (QTZ-R) 3 ] 2+ , were obtained as mixtures of facial (fac) and meridional (mer) isomers, as suggested by NMR (1H, 13C) experiments, and confirmed in the case of mer-[Ru (QTZ-Me) 3 ] 2+ , by X-ray crystallography. The photophysical behavior of the tetrazole-based [Ru(N^N) 3 ] 2+ type species was investigated by UV–vis absorption spectroscopy, providing trends typical of polypyridyl Ru (II) complexes. The new homoleptic complexes fac/mer- [Ru (PTZ-R) 3 ] 2+ and fac/mer- [Ru (QTZ-R) 3 ] 2+ have been assessed for any eventual antimicrobial activity towards two different bacteria such as Gram-negative Escherichia coli and Gram-positive Deinococcus radiodurans. Whereas being inactive toward E. coli, the response of agar disks diffusion tests suggested that some of the new fac/mer Ru (II) complexes could inhibit the growth of D. radiodurans. This effect was further investigated by determining the growth kinetics in liquid medium of D. radiodurans exposed to the fac/mer- [Ru (PTZ-R) 3 ] 2+ and fac/mer- [Ru (QTZ-R) 3 ] 2+ complexes at different concentrations. The outcome of these experiments highlighted that the turn-on of the growth inhibitory effect took place as the linear hexyl chain was appended to the PTZ or QTZ scaffold, suggesting also how the inhibitory activity appeared more pronouncedly exerted by the facial isomers fac- [Ru (PTZ-Hex) 3 ] 2+ and fac- [Ru (QTZ-Hex) 3 ] 2+ (MIC = ca. 3.0 μg/ml) with respect to the corresponding meridional isomers (MIC = ca. 6.0 μg/ml). 相似文献
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Paolo Bruni Carla Conti Elisabetta Giorgini Giorgio Tosi Henning Hopf Jorg Hillmer 《Monatshefte für Chemie / Chemical Monthly》1992,123(1-2):73-80
Summary Molecular complexes of mono and disubstituted [2.2]paracyclophanehydrazones with organic acceptors have been studied by means of thermodynamic and spectroscopic properties. Furthermore, the enhancement of the donor strength, induced by the hydrazono group, is viewed in the light of substituent as well as transannular effects.
Molekulare Assoziation von [2.2]Paracyclophanarylhydrazonen mit organischen Akzeptoren, 8. Mitt.
Zusammenfassung Es wurden Molekülkomplexe von mono- und disubstituierten [2.2]Paracyclophanarylhydrazonen mit organischen Akzeptoren mittels thermodynamischer und spektroskopischer Methoden untersucht. Zusätzlich wird der Anstieg in der Donorstärke, der von der Hydrazonogruppe induziert wird, im Hinblick auf Substituenten- und auch transannulare Effekte diskutiert.相似文献
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Paolo Bruni Gabriele Bocelli Andrea Cantoni Elisabetta Giorgini Marco Iacussi Eziana Maurelli Giorgio Tosi 《Journal of chemical crystallography》1995,25(10):683-691
Complexes of azobisindoles with tetracyanoethylene and tetracyanoquinodimethane were studied by UV-Vis, FT-IR, Raman, NMR and X-ray spectroscopies. FT-IR and Raman spectra, as well as X-ray analysis, gave useful information on the participation of various sites to the association, through analysis of CN and N=N vibrational modes, while UV-Vis and NMR spectra were less helpful. The crystal structure of complexes 1-ethyl-2-phenyl-3-(1-ethyl-2-phenyl-3-azoindole)indole/TCNE,3a and 1,2-diphenyl-3-(1,2-diphenyl-3-azoindole)indole/TCNQ,5b are reported. In the two complexes, the distances between donor and acceptor planes range between 3.4 and 3.5 Å; in3a tetracyanoethylene faces the phenyl ring of the indole, while in5b the superposition of tetracyanoquinodimethane with the donor is negligible. Compound3a,P–1,a=9.504(2),b=9.513(3),c=8.941(2) Å, =97.81(4), =103.38(3), =84.14(2)°,Z=2,D
calc=2.55 g cm–3; compound5b,P–1,a=12.648(3),b=12.205(2),c=7.263(3) Å, =103.69(2), =91.23(3), =110.61(2)°,Z=2,D
calc=2.53 g cm–3. 相似文献