Volume 95, Issue 7

Lipids in the Ready-to-use Therapeutic Food (RUTF) comprise various types of triglycerides such as palmitic, oleic and linoleic acids. Dynamic studies of the dielectric properties such as impedance, permittivity and loss tangent of the triglycerides at different temperatures ranging from 25 to −30 °C and frequencies from 10 −2 Hz to 5 × 10 6 Hz were performed by electrochemical impedance spectroscopy (EIS). The outcomes of EIS were associated together with the analysis of Fourier-transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC) in order to analyse the dielectric signals obtained. As expected, FTIR results suggest the presence of saturated and unsaturated triglycerides of the palmitic, oleic and linoleic acids. Besides, there are absorbance bands of functional groups that reflect the presence of proteins. The dielectric relaxation and dielectric constant were evaluated from the impedance and permittivity spectra, respectively. The results imply the RUTF possesses long-range motion of dipoles against lower temperatures. The phase transitions observed in RUTF as indicated by the DSC cooling curve (crystallization), lead to the shifting of dielectric properties in impedance and permittivity.

The effect of titanium dioxide (TiO 2 ) on the thermal properties, morphology, intermolecular interactions, and dielectric response of poly(ethylene oxide)/poly(methyl acrylate) (PEO/PMA) polymer electrolytes was studied. These properties were elucidated based on the empirical point of view through systematic sample characterization using differential scanning calorimetry (DSC), polarized optical microscopy (POM), Fourier-transform infrared (FTIR) spectroscopy and impedance spectroscopy (IS). Without TiO 2 , lithium perchlorate preferably dissolves in the PEO phase rather than in the PMA phase. When TiO 2 is added into PEO/PMA/salt systems, TiO 2 shows weak interactions either with PEO or PMA phase. The addition of TiO 2 changes the morphology of PEO/PMA systems with or without salt from a homogeneous mixture to a heterogeneous mixture displayed by the presence of two T g s and through the morphological study. The conductivity of both PEO/PMA with and without salt systems remains constant upon the addition of TiO 2 . Hence, the presented data here have shown that TiO 2 provides only a minor effect on the properties of PEO/PMA with and without salt systems. Indirectly, it shows by adding TiO 2 under this experimental study may not bring a significant contribution to the improvement of polymer electrolytes.

Aminopeptidases selectively hydrolyze an aminoacid residue from the amino terminus of proteins and peptides resulting in their activation or inactivation. These enzymes are mainly metallo and belong, among other, to the M1 family of peptidases. One of its members, membrane glutamyl aminopeptidase (APA, EC 3.4.11.7) participates in many physiological processes, such as peptide metabolism related with blood pressure control, and last step of protein degradation. Furthermore, the up regulation of APA has been implicated in the pathogenesis of various human disorders like cancers, hypertension and glomerulosclerosis. APA is thus a target for the development of inhibitors with potential biomedical applications. We review the most important structural and functional characteristics of mammalian APA, focusing on the most recent data. Additionally, we integrate the roles of APA in physio- and pathophysio-logical processes of biomedical relevance with the development of specific APA inhibitors.

We determined the most preferred site for the electrophilic aromatic substitution (S E Ar) reactions of thiophene 1 and thieno[2,3- b ]thiophene 2 using the N -chlorosuccinimide electrophile in the gas phase and in acetic acid. The B3LYP/6-311G(d), B3LYP-D3/6-311G(d) and M06-2X/6-311G(d) methods were employed to investigate the S E Ar reaction mechanisms. We found that, compared to the β-carbon atom, the α-carbon atom in both 1 and 2 is preferred for electrophilic attack both kinetically and thermodynamically.

Bufadienolides are steroids that inhibit the Na + /K + ATPase pump. Recent studies show that members of the bufadienolide family also inhibit the activity of aminopeptidase N (APN). APN is upregulated in different pathologies, including cancer and is a current target for drug development. Bufadienolides are cytotoxic in tumor cells, but there is no enough evidences that inhibition of APN activity contributes to their effect. In the present contribution we investigated the effect of another member of the bufadienolide family, bufotalin, on porcine APN (pAPN) activity. Bufotalin inhibited pAPN activity with K i values in the submicromolar range and an uncompetitive inhibition mechanism; it also inhibited porcine aminopeptidase A (pAPA) activity, but with a classical reversible competitive inhibition mechanism. In addition, we determined the effect of bufotalin on the viability/metabolism of APN+ A549, H292, MeWo and CT26 cancer cells. Bufotalin was cytotoxic in a dose dependent manner; the highest cytotoxicity was detected in A549 cells, the cells with the highest APN activity. Thus, tumor cell line sensitivity to the cytotoxic effect of bufotalin correlates with cell surface APN activity.

Successful synthesis of several dibutyl-, diphenyl- and triphenyltin(IV) carboxylate compounds and evaluation of their activity as anticancer against leukemia cancer cell, L-1210 was reported. The compounds were synthesized by reacting dibutyltin(IV) oxide (DBTO) ( 1 ), diphenyltin(IV) oxide (DPTO) ( 4 ) and triphenyltin(IV) hydroxide (TPTOH) ( 7 ) with respective carboxylic acids, and subsequently characterized using NMR, FTIR, and UV–Vis spectroscopies, microelemental analyzer, and melting point apparatus. The compounds were then tested as anticancer, revealing that derivatives of triphenyltin(IV) (compounds 8 dan 9 ) exhibit the IC 50 value of 3.7 and 2.9 μg/mL, respectively, which are much higher activity than those of dibutyltin(IV) and diphenyltin(IV) derivatives.

Ethaline, the 1:2 molar ratio mixture of ethylene glycol (EG) and choline chloride (ChCl), is generally regarded as a typical type III deep eutectic solvent (DES). However, careful differential scanning calorimetry (DSC) of EG + ChCl mixtures surprisingly revealed that the liquidus lines of the phase diagram apparently follow the predictions for an ideal binary non-electrolyte mixture. Applying broad-band dielectric relaxation spectroscopy to room-temperature solutions of ChCl, and of the related salts choline iodide and chlorocholine chloride, in EG up to saturation, we explored the possible reasons for this conundrum. It appears that in these solutions free ions are rather scarce. Instead, contact ion pairs and larger aggregates predominate.

Ionic liquids are among the most studied systems in recent years, and this field is still growing considerably, focusing not only on fundamental research but also on the development of ionic liquids for specific applications. In this paper, the similarities and differences between conventional, “classical” electrolytes and common surfactants and ionic liquids, as well as the surface-active ionic liquids, are discussed to highlight their importance and point out their weaknesses. A brief review of the literature data shows that ionic liquids behave like “classical” electrolytes in solutions and can be described by existing models within the range of their validity. Models that describe concentrated electrolyte solutions well are still lacking, and here ionic liquids, which are less constrained by solubility than ordinary electrolytes, can serve as model systems. The micellization of surface-active ionic liquids in aqueous solutions can be described in the same way as for conventional surfactants, but surface-active ionic liquids offer more opportunities to study specific ion and isomer effects.