In Silico and Experimental Investigation of the Biological Potential of Some Recently Developed Carprofen Derivatives

The efficient regioselective bromination and iodination of the nonsteroidal anti-inflammatory drug (NSAID) carprofen were achieved by using bromine and iodine monochloride in glacial acetic acid. The novel halogenated carprofen derivatives were functionalized at the carboxylic group by esterification. The regioselectivity of the halogenation reaction was evidenced by NMR spectroscopy and confirmed by X-ray analysis. The compounds were screened for their in vitro antibacterial activity against planktonic cells and also for their anti-biofilm effect, using Gram-positive bacteria (Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212) and Gram-negative bacteria (Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853). The cytotoxic activity of the novel compounds was tested against HeLa cells. The pharmacokinetic and pharmacodynamic profiles of carprofen derivatives, as well as their toxicity, were established by in silico analyses.     

Pseudopolymorphic transitions of niclosamide monitored by Raman spectroscopy

Niclosamide suffers pseudopolymorphic transformations when exposed to different ambient conditions, which can lead to changes in its bioavailability. In this study, the kinetics of the pseudopolymorphic transitions of niclosamide crystals are characterized. FT‐Raman spectroscopy is used to quantify the anhydrate and hydrate forms of niclosamide crystals, mostly because of its high sensitivity to the strong intermolecular interactions present in these systems. The samples are exposed to well‐characterized relative humidity (RH) conditions during different periods of time and both water diffusion and polymorphic changes are monitored from the corresponding changes observed in the vibrational spectra. Both hydration and dehydration were found to be single‐step processes, with a half‐life time of ca. 142 and 63 h, respectively, at 24 °C. Copyright © 2008 John Wiley & Sons, Ltd.     

On the spectra of periodic waves for infinite-dimensional Hamiltonian systems

We consider the problem of determining the spectrum for the linearization of an infinite-dimensional Hamiltonian system about a spatially periodic traveling wave. By using a Bloch-wave decomposition, we recast the problem as determining the point spectra for a family of operators J_γL_γ, where J_γ is skew-symmetric with bounded inverse and L_γ is symmetric with compact inverse. Our main result relates the number of unstable eigenvalues of the operator J_γL_γ to the number of negative eigenvalues of the symmetric operator L_γ. The compactness of the resolvent operators allows us to greatly simplify the proofs, as compared to those where similar results are obtained for linearizations about localized waves. The theoretical results are general, and apply to a larger class of problems than those considered herein. The theory is applied to a study of the spectra associated with periodic and quasi-periodic solutions to the nonlinear Schrödinger equation, as well as periodic solutions to the generalized Korteweg-de Vries equation with power nonlinearity.     

Physicochemical and Antioxidant Properties of Riboflavin in Dextran70/HSA Systems

Physicochemical properties of Riboflavin (Vitamin B₂) (RF), in Dextran 70 (Dx70) (a biological relevant glucidic type macromolecule) and Human Serum Albumin (HSA) (a carrier/transport protein) based system, have been studied by absorption, fluorescence, circular dichroism and electrochemistry. No significant changes on the fluorescence of RF in Dx70/HSA systems with and without the influence of temperature (30–60 °C range) were observed. No changes on the intrinsic Tryptophan fluorescence in Dx70/RF/HSA system, have been evidenced. HSA secondary structure when RF binds in Dx70/RF/HSA systems, with a renaturation effect of Dx70, was found. In Dx70/RF/HSA system the major process which RF undergoes is the proton transfer, E_red = ?0.43 V. Using the chemiluminescence method, an improvement of the antioxidant activity of RF into the Dx70/RF/HSA system, was also found. RF concentration in Dx70/RF/HSA systems is important in RF oxidative damages when it reacts with target molecules and thus promotes their oxidation. The results have relevance in the oxidative stress process and in pharmaceutical formulations containing RF.     

Temperature‐dependent,micro‐Raman spectroscopic study of barium titanate nanoparticles

A comparative, temperature‐dependent (80–500 K at 5 K intervals), micro‐Raman spectroscopic study of 300 and 50 nm diameter ceramic BaTiO₃ nanoparticles was carried out with the purpose of elucidating the nanoparticle size effect on the temperature dependence of the polar and non‐polar phonons. A method for calibrating Raman intensities, along with an iterative spectral fitting algorithm, is proposed for concurrent Raman band position and intensity analysis, increasing the analytical abilities of single temperature point Raman spectroscopy. The 300 nm particles exhibit all three phase transitions, whereas the 50 nm particles do not show evidence of these phase transitions in the same temperature range. The Curie temperature appears to be a phonon converging point, irrespective of the phonon symmetry. An attempt was made to qualitatively relate the temperature‐dependent Raman spectra to complimentary non‐spectroscopic methods, such as heat capacity and X‐ray diffraction studies. The study proves that the temperature‐dependent behavior of the polar phonon, 265 cm⁻¹, can be utilized as a sensitive phase transition probe. Copyright © 2014 John Wiley & Sons, Ltd.     

An improved biosensor for acetaldehyde determination using a bienzymatic strategy at poly(neutral red) modified carbon film electrodes

Improved biosensors for acetaldehyde determination have been developed using a bienzymatic strategy, based on a mediator-modified carbon film electrode and co-immobilisation of NADH oxidase and aldehyde dehydrogenase. Modification of the carbon film electrode with poly(neutral red) mediator resulted in a sensitive, low-cost and reliable NADH detector. Immobilisation of the enzymes was performed using encapsulation in a sol-gel matrix or cross-linking with glutaraldehyde. The bienzymatic biosensors were characterized by studying the influence of pH, applied potential and co-factors. The sol-gel and glutaraldehyde biosensors showed a linear response up to 60 μM and 100 μM, respectively, with detection limits of 2.6 μM and 3.3 μM and sensitivities were 1.7 μA mM⁻¹ and 5.6 μA mM⁻¹. The optimised biosensors showed good stability and good selectivity and have been tested for application for the determination of acetaldehyde in natural samples such as wine.     

Enzymatic hydrolysis optimization to ethanol production by simultaneous saccharification and fermentation

There is tremendous interest in using agro-industrial wastes, such as cellulignin, as starting materials for the production of fuels and chemicals. Cellulignin are the solids, which result from the acid hydrolysis of the sugarcane bagasse. The objective of this work was to optimize the enzymatic hydrolysis of the cellulose fraction of cellulignin, and to study its fermentation to ethanol using Saccharomyces cerevisiae. Cellulose conversion was optimized using response surface methods with pH, enzyme loading, solid percentage, and temperature as factor variables. The optimum conditions that maximized the conversion of cellulose to glucose, calculated from the initial dried weight of pretreated cellulignin, (43 degrees C, 2%, and 24.4 FPU/g of pretreated cellulignin) such as the glucose concentration (47 degrees C, 10%, and 25.6 FPU/g of pretreated cellulignin) were found. The desirability function was used to find conditions that optimize both, conversion to glucose and glucose concentration (47 degrees C, 10%, and 25.9 FPU/g of pretreated cellulignin). The resulting enzymatic hydrolyzate was fermented yielding a final ethanol concentration of 30.0 g/L, in only 10 h, and reaching a volumetric productivity of 3.0 g/L x h, which is close to the values obtained in the conventional ethanol fermentation of sugar cane juice (5.0-8.0 g/L x h) in Brazil.     

Osmium assay in fixatives and stained rat tissues by means of acid and <Emphasis Type="Italic">o,o</Emphasis>′-dihydroxo substituted monoazo dyes and some flavonoids

New simple, rapid and accurate spectrophotometric techniques for osmium assays in fixatives and stained tissues have been elaborated using acid (Tropaeolin O, Tropaeolin OOO-I, Tropaeolin OOO-II, Orange G), o,o′-dihydroxo substituted azo dyes (Eriochrome Blue Black R, Acid Chrome Dark-Blue, Eriochrome Black T) and flavonoids (morin, quercetin, luteolin). Methods are based on sensitive osmium(IV) reactions with reagents and the formation of stable coloured compounds. Tolerance ratios of main matrix components of histological specimens during Os(IV) spectrophotometric determination with reagents has been established. Results of osmium determination in fixatives and fixed tissues, obtained by means of different reagents, appeared to be sufficiently similar, although effects of matrix components differ. The accuracy of spectrophotometric osmium assay in fixatives with azo dyes has been confirmed with voltammetric investigations. Results obtained from osmium uptake by rat gum tissues are valuable for clinical testing of dental drugs, indicating the influence of drug treatment on the gums.      

Energy release rate approximation for small surface-breaking cracks using the topological derivative

The topological derivative provides the variation of a response functional when an infinitesimal hole of a particular shape is introduced at a point of the domain. In this fracture mechanics work we use the topological derivative to approximate the energy release rate field associated with a small crack at any boundary location and at any orientation. Our proposed method offers significant computational advantages over current finite element based methods since it requires a single analysis, whereas the others require a distinct analysis for each crack location-orientation combination. Moreover, the proposed method evaluates the topological derivative in the non-cracked domain which eliminates the need for tailored meshes in the crack region.