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141.
Silva OF Silber JJ de Rossi RH Correa NM Fernandez MA 《The journal of physical chemistry. B》2007,111(36):10703-10712
The formation of reverse micelles (RMs) of sodium 1,4-bis(2-ethylhexyl)sulfosuccinate (AOT) in n-heptane including two different beta-cyclodextrin (beta-CD) derivatives (hydroxypropyl-beta-CD, hp-beta-CD, and decenyl succinyl-beta-CD, Mod-beta-CD) is reported. Both cyclodextrins can be incorporated into AOT RMs in different zones within the aggregate, while beta-CD cannot. Using UV-vis and induced circular dichroism (ICD) spectroscopy and different achiral molecular probes (some azo dyes, p-nitroaniline and ferrocene), it was possible to determine that Mod-beta-CD is located with its cavity at the oil side of the AOT RM interface, while for hp-beta-CD the cavity is inside the RM water pool. Among the molecular probes used, methyl orange (MO) was the only one which gave the ICD signal when dissolved in the AOT RMs with hp-beta-CD, so a detailed study of MO behavior in homogeneous media was also performed to compare with the microheterogeneous media. The solvatochromic behavior of the dye depends not only on the polarity of the media but also on other specific solvent properties. A Kamlet-Taft analysis shows that the MO absorption spectrum shifts to longer wavelength with an increase in the solvent polarity-polarizability (pi*) and the hydrogen donor ability (alpha) of the medium. MO appears to be almost 3 times more sensitive to the pi* parameter than to the alpha parameter. In addition, from the MO absorption spectral changes with the hp-beta-CD concentration, the association equilibrium constants in pure water (K11W) and inside the RMs (K11RM) were computed. The results show that K11W is almost 10 times larger than the value inside the RMs. The latter can be explained considering that MO resides anchored to the RM interface through hydrogen bond interaction with the hydration bound water. This study shows for the first time that the cyclodextrin chiral cavity is available for a guest in an organic medium such as the RMs; therefore, we have created a potentially powerful nanoreactor with two different confined regions in the same aggregate: the polar core of the RMs and the chiral hydrophobic cavity of cyclodextrin. 相似文献
142.
Agibert SA Moreira MB Ratusznei SM Rodrigues JA Zaiat M Foresti E 《Applied biochemistry and biotechnology》2007,136(2):193-206
The effect of temperature on the performance of an anaerobic sequencing biofilm batch reactor (ASBBR) with liquid-phase recirculation
was assessed. Assays were performed using a recirculation velocity of 0.20 cm/s, 8-h cycles, and an average treated synthetic
wastewater volume of 2 L/cycle with a concentration of 500 mg of Chemical Oxygen Demand (COD)/L. Operation temperatures were
15, 20, 25, 30, and 35°C. At 25, 30, and 35°C, organic matter removal efficiencies for filtered samples ranged from 81 to
83%. At lower temperatures, namely 15 and 20°C, removal efficiency decreased significantly to 61 and 65%, respectively. A
first-order model could be fitted to the experimental concentration profile values. The first-order kinetic parameter value
of this model varied from 0.46 to 0.81 h1 considering the lowest and highest temperature studied. Moreover, analysis of the removal profile values allowed fitting
of an Arrhenius-type equation with an activation energy of 5715 cal/mol. 相似文献
143.
Milen G. Bogdanov Mariana D. Palamareva Blagovesta T. Gocheva Darina B. Dimitrova 《Journal of heterocyclic chemistry》2007,44(3):673-677
The reaction between homophthalic anhydride and cyclohexanone was examined both in the presence of DMAP or BF3·Et2O complex as a catalyst. The latter yielded (±)‐1‐oxo‐1H‐spiro[benzo[c]pyran‐3(4H), 1′‐cyclohexane]‐4‐carboxylic acid ( 3 ) in a higher yield (82 %). A series of new (±)‐4‐(N,N‐disubstituted‐1‐carbamoyl)‐1H‐spiro[benzo[c]pyran‐3(4H),1′‐cyclohexane]‐1‐ones ( 5a‐h ) were synthesized from the parent acid 3 by a two‐step reaction. Differentiating microbial screening was performed for most of the synthesized compounds against twelve microorganisms belonging to different taxonomic groups. The spiro acid 3 was active against all bacterial strains with MIC ≥ 20 μg/ml against B. subtillis and P. vulgaris. E. coli was the most sensitive strain to the antibacterial effect of the tested compounds. 相似文献
144.
Mariana Sardo Ana M. Amado Paulo J. A. Ribeiro‐Claro 《Journal of Raman spectroscopy : JRS》2009,40(12):1956-1965
The importance of hydrogen‐bond formation in the molecular packing arrangements of two anhydrous forms of nitrofurantoin is investigated, combining computational methods and spectroscopic data. The overall results indicate, as expected, that the vibrational modes related to the CO, N H and C H groups are strongly affected by intermolecular hydrogen‐bond formation. Moreover, the importance of weak C‐H···O interactions in conferring additional stability to molecular associations in biological systems is evidenced in this study. The complete assignment of the Raman and infrared spectra of both polymorphs is accomplished by means of a computationally based methodology, which accounts for the effects of intermolecular interactions in the crystal. The vibrational shifts due to crystal packing interactions are evaluated from DFT calculations for a set of suitable molecular pairs, using the B3LYP/6‐31G* approach. This methodology provides an answer to the current demand for a reliable and complete assignment of the vibrational spectra of pharmaceutically active compounds such as nitrofurantoin. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
145.
Marjorie C. L. C. Freire Gabriela D. Noske Natlia V. Bitencourt Paulo R. S. Sanches Norival A. Santos-Filho Victor O. Gawriljuk Eduardo P. de Souza Victor H. R. Nogueira Mariana O. de Godoy Aline M. Nakamura Rafaela S. Fernandes Andre S. Godoy Maria A. Juliano Bianca M. Peres Cecília G. Barbosa Carolina B. Moraes Lucio H. G. Freitas-Junior Eduardo M. Cilli Rafael V. C. Guido Glaucius Oliva 《Molecules (Basel, Switzerland)》2021,26(16)
The COVID-19 outbreak has rapidly spread on a global scale, affecting the economy and public health systems throughout the world. In recent years, peptide-based therapeutics have been widely studied and developed to treat infectious diseases, including viral infections. Herein, the antiviral effects of the lysine linked dimer des-Cys11, Lys12,Lys13-(pBthTX-I)2K ((pBthTX-I)2K)) and derivatives against SARS-CoV-2 are reported. The lead peptide (pBthTX-I)2K and derivatives showed attractive inhibitory activities against SARS-CoV-2 (EC50 = 28–65 µM) and mostly low cytotoxic effect (CC50 > 100 µM). To shed light on the mechanism of action underlying the peptides’ antiviral activity, the Main Protease (Mpro) and Papain-Like protease (PLpro) inhibitory activities of the peptides were assessed. The synthetic peptides showed PLpro inhibition potencies (IC50s = 1.0–3.5 µM) and binding affinities (Kd = 0.9–7 µM) at the low micromolar range but poor inhibitory activity against Mpro (IC50 > 10 µM). The modeled binding mode of a representative peptide of the series indicated that the compound blocked the entry of the PLpro substrate toward the protease catalytic cleft. Our findings indicated that non-toxic dimeric peptides derived from the Bothropstoxin-I have attractive cellular and enzymatic inhibitory activities, thereby suggesting that they are promising prototypes for the discovery and development of new drugs against SARS-CoV-2 infection. 相似文献
146.
In this work we perform an ab initio study of the electric field gradient (EFG) at the nucleus of Fe impurities in crystalline SnO. The Augmented Plane Waves plus Local Orbitals method is used to obtain the electronic structure of the doped system and the atomic relaxations introduced by the impurities in the SnO host in a fully self-consistent way. Most calculations are performed assuming that Fe ions replace the Sn atoms of the structure, in some cases including oxygen vacancies in order to discuss their role in the hyperfine interactions and in determining the local structure around Fe impurities. The case of interstitial Fe sites is also considered. Our predictions are compared with available Müssbauer spectroscopy results and also with theoretical and experimental results obtained for rutile SnO2 and TiO2. 相似文献
147.
Fifere Adrian Tania Budtova Elena Tarabukina Mariana Pinteala Spulber Mariana Cristian Peptu Valeria Harabagiu Bogdan C. Simionescu 《Journal of inclusion phenomena and macrocyclic chemistry》2009,64(1-2):83-94
Carboxyl modified γ-cyclodextrin (CDSA) with a substitution degree of about 9.5 was prepared by the esterification of γ-cyclodextrin (CD) with succinic anhydride in pyridine at 90 °C. The chemical composition and the structure of CDSA were characterized by FT-IR, MALDI-TOF, X-ray diffraction pattern, potentiometric titration and TGA. Modified and native γ-cyclodextrin associate with fullerene (C60) in DMF-toluene mixture resulting 1:1 CDSA:C60 and CD:C60 inclusion complexes. Aqueous solutions of native cyclodextrin, carboxyl-modified cyclodextrin and their inclusion complexes with C60 were used as microgel solvent (or swelling agent) for controlled release application. The release of solutions was induced by shear stress and demonstrated using rheo-optical set-up. 相似文献
148.
Manuel A.V. Ribeiro da Silva Ana I.M.C. Lobo Ferreira Joana I.T.A. Cabral Ana Filipa L.O.M. Santos Ana Rita G. Moreno Tiago L.P. Galvão Inês M. Rocha Paula M.V. Fernandes Sílvia Q. Salgueiro Vanessa A.F. de Moura Isabel M.S.C. Oliveira Paula C. Cotelo Mariana R.A. Ribeiro 《The Journal of chemical thermodynamics》2009,41(9):984-991
149.
André Romero da Silva Natalia Mayumi Inada Daniel Rettori Mariana Ozello Baratti Anibal Eugenio Vercesi Renato Atilio Jorge 《Journal of photochemistry and photobiology. B, Biology》2009,94(2):101-112
In(III)-meso-tetraphenylporphyrin (InTPP) was encapsulated into nanoparticles (smaller than 200 nm) of poly(d,l-lactide-co-glycolide) (PLGA) using the emulsification–evaporation technique. The photodynamic efficacy of InTPP-loaded nanoparticles and its cellular uptake was investigated with LNCaP prostate tumour cells, in comparison with the free InTPP. The effects of incubation time (1–3 h), drug concentration (1.8–7.7 μmol/L) and incident light dose (15–45 J/cm2) with both encapsulated and free InTPP were studied. The type of cell death induced by the photochemical process using both encapsulated and free InTPP was also investigated. Cell viability was reduced more significantly with increasing values of these effects for InTPP-loaded nanoparticles than with the free drug. The cellular death induced by both encapsulated and free InTPP was preponderantly apoptotic. Confocal laser scanning microscopy data showed that the InTPP-loaded nanoparticles, as well free InTPP, were localized in the cells, and always in the perinuclear region. Encapsulated InTPP was measured by the intensity of fluorescence intensity of cell extracts and was three times more internalized into the cells than was the free InTPP. Electron paramagnetic resonance experiments corroborated the participation of singlet oxygen in the photocytotoxic effect of nanoparticles loaded with InTPP. 相似文献
150.
Mariana Macías-Alonso Nuria Esturau-Escofet Marcos Flores-Álamo Martín A. Iglesias-Arteaga Rafael Moreno-Esparza 《Journal of chemical crystallography》2011,41(10):1476-1482