Characterization and compatibility of dry extract from Annona muricata L. and pharmaceutical excipients

Journal of Thermal Analysis and Calorimetry - The aim of this study was to characterize and evaluate the compatibility of the dry extract (DE) of leaves of Annona muricata L. with pharmaceutical...     

The effect of ammonium sulfate on the solubility of amino acids in water at (298.15 and 323.15) K

Using the analytical gravimetric method the solubility of glycine, dl-alanine, l-isoleucine, l-threonine, and l-serine in aqueous systems of (NH₄)₂SO₄, at (298.15 and 323.15) K, were measured for salt concentrations ranging up to 2.0 molal.In the electrolyte molality range studied the experimental observations showed that ammonium sulfate is a salting-in agent for most of the amino acids studied. Furthermore, the change of the relative solubility with electrolyte concentration shows a maximum, which makes the representation of the data by a simple empirical correlation such as the Setschenow equation difficult. For the development and evaluation of a robust thermodynamic framework that makes it possible to more profoundly understand aqueous amino acid solutions with ammonium sulfate additional experimental information is needed.     

Water solubility of drug-like molecules with the cubic-plus-association equation of state

Although of extreme importance for evaluating the effective therapeutic action, aqueous solubility data involving drug-like molecules are scarce. Thermodynamic models can be used to estimate these solubilities, and different models, namely activity coefficient models, have been applied for that purpose. Still, these frequently cannot describe with accuracy broad temperature and pressure ranges, various solvent compositions or multifunctional molecules.     

Solute partitioning in polymer–salt ATPS: The Collander equation

The partition coefficients for several solutes (five nitrophenylated-monosaccharides and four proteins) were experimentally determined, at 23 °C, in three different tie-lines of two polymer–salt aqueous two-phase systems (ATPS): UCON-K₂HPO₄ and UCON-NaH₂PO₄. These partition coefficients together with others obtained from the literature for five dinitrophenylated-amino acids were used to investigate the suitability of the Collander equation to correlate partition coefficients in polymer–salt ATPS. This equation was first proposed to describe the linear correlation between partition coefficients of solutes in different water–organic solvent systems. More recently, it was proved that partition coefficients for several biomolecules in polymer–polymer ATPS can also be correlated with this equation. In this work, several correlations were tested: partition coefficients obtained for different tie-lines within the same system and also partition coefficients obtained from different systems. In both cases, a linear relation was observed, despite a less satisfactory correlation was found when different ATPS were compared. Overall, it was demonstrated that the Collander equation can be used to satisfactorily correlate solute partitioning in the studied polymer–salt ATPS.     

Concentration-compactness principle for an inequality by D. Adams

This paper brings a generalization of the Lions concentration–compactness principle to the Sobolev space \(W_0^{m,p}(\Omega )\) when \(mp=n\) and \(\Omega \subset \mathbb {R}^n \, (n \ge 2)\) is a smooth domain with finite \(n\) -measure. Moreover, our result sharpens an inequality by D. Adams improving its best exponent. The proof is established using the decreasing rearrangement and comparison principle due to Talenti combined with the maximum principle. It is also shown how this concentration–compactness principle yields the existence of critical points of mountain-pass type for an energy functional associated with a class of polyharmonic problems.     

Vapour pressures and osmotic coefficients of binary mixtures of 1-ethyl-3-methylimidazolium ethylsulfate and 1-ethyl-3-methylpyridinium ethylsulfate with alcohols at T = 323.15 K

Osmotic coefficients of binary mixtures containing alcohols (ethanol, 1-propanol, and 2-propanol) and the ionic liquids 1-ethyl-3-methylimidazolium ethylsulfate and 1-ethyl-3-methylpyridinium ethylsulfate were determined at T = 323.15 K. Vapour pressure and activity coefficients of the studied systems were calculated from experimental data. The extended Pitzer model modified by Archer, and the modified NRTL model (MNRTL) were used to correlate the experimental data, obtaining standard deviations lower than 0.012 and 0.031, respectively. The mean molal activity coefficients and the excess Gibbs free energy of the studied binary mixtures were calculated from the parameters obtained with the extended Pitzer model of Archer.     

Profiling changes triggered during maturation of dendritic cells: a lipidomic approach

Lipids are important in several biological processes because they act as signalling and regulating molecules, or, locally, as membrane components that modulate protein function. This paper reports the pattern of lipid composition of dendritic cells (DCs), a cell type of critical importance in inflammatory and immune responses. After activation by antigens, DCs undergo drastic phenotypical and functional transformations, in a process known as maturation. To better characterize this process, changes of lipid profile were evaluated by use of a lipidomic approach. As an experimental model of DCs, we used a foetal skin-derived dendritic cell line (FSDC) induced to mature by treatment with lipopolysaccharide (LPS). The results showed that LPS treatment increased ceramide (Cer) and phosphatidylcholine (PC) levels and reduced sphingomyelin (SM) and phosphatidylinositol (PI) content. Mass spectrometric analysis of a total lipid extract and of each class of lipids revealed that maturation promoted clear changes in ceramide profile. Quantitative analysis enabled identification of an increase in the total ceramide content and enhanced Cer at m/z 646.6, identified as Cer(d18:1/24:1), and at m/z 648.6, identified as Cer(d18:1/24:0). The pattern of change of these lipids give an extremely rich source of data for evaluating modulation of specific lipid species triggered during DC maturation.     

Structural and Mössbauer investigation on barium titanate–cobalt ferrite composites

Perovskite and spinels oxides have received renewed attention due to the possibility of combining both structures in di-phase composites to obtain multifunctional materials. In this work, barium titanate (perovskite)-cobalt ferrite (spinel) composite powders with different microstructures were obtained from thermal treatment of amorphous precursors at 500–1100 °C. The precursors were prepared by combining coprecipitation and sol–gel routes. Lyophilization of ferrite prior to mixing was used as a strategy to control interphase reaction. Mössbauer spectroscopy showed that the dispersion of coprecipitated ferrite in a viscous BaTiO₃ precursor gel resulted in superparamagnetic behavior and reduction of the local magnetic field of site [B].