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HLA epitope analysis emerged as a strategy to determine alloimmune risk in solid organ transplantation. However, it requires not only knowledge on HLA amino acids sequences, but also on HLA three-dimensional structures. Unfortunately, the number of structures available is still unsatisfactory. This work reports the modelling of 106 heterotrimeric (alpha chain + β2M + peptide) HLA class I molecules. The models were generated by homology modelling using Modeller, refined using GalaxyRefine server, heterodimerized with Swiss-PDB Viewer and, finally, assessed as to their structural quality through Dali server. The final structures were made available through a free online database, pHLA3D ( www.phla3d.com.br ), developed in Ruby language using the Ruby on Rails web framework. Structural parameters were similar between refined molecules and their templates. The new database may improve HLA epitope analysis and better guide risk assessment in solid organ transplantation setting.

We performed a biological evaluation of antileishmanial activity, in silico ADME-Tox profile, and molecular docking of riparins A-F. The antileishmanial activity was evaluated in Leishmania major promastigotes, whereas the cytotoxic activity was tested on murine macrophages. Computational parameters were predicted by in silico analysis. Molecular docking was performed with 18 L. major molecular targets. Riparins, especially RipC and RipE, showed cytotoxic activity in vitro toward L. major promastigotes and a high selectivity index. Riparins showed small differences in their physicochemical properties, such as polarity and aqueous solubility. LogP was an important parameter for the differences in the antileishmanial activity between the molecules. In molecular docking, the ligands displayed Ki 1 μM for LmNMT and LmLEI. Significant molecular interactions were observed with residues from the active site and adjacent regions of such enzymes. Thus, riparins have the potential for application in antileishmanial therapy.

This study performed a physicochemical characterization of the inclusion complex generated between Riparin A and β-cyclodextrin (Rip A/β-CD) and compared the cytotoxic potential of the incorporated Rip A upon Artemia salina larvae. Samples were analyzed by phase solubility diagram, dissolution profile, differential scanning calorimetry, X-ray diffraction, infrared spectroscopy, proton nuclear magnetic resonance, scanning electron microscopy and artemicidal action. Riparin A/β-cyclodextrin complexes presented increased water solubility, AL type solubility diagram and Kst constant of 373 L/mol. Thermal analysis demonstrated reduction of the melt peak of complexed Rip A at 116.2 °C. Infrared spectroscopy confirmed generation of inclusion complexes, 1H NMR pointed out the interaction with H-3 of β-CD cavities, alterations in the crystalline natures of Rip A when incorporated within β-CD were observed and inclusion complexes presented higher cytotoxic on A. salina nauplii, with CL50 value of 117.2 (84.9–161.8) μg/mL. So, Rip A was incorporated into β-CDs with high efficiency and water solubility of Rip A was improved. Such solubility was corroborated by cytotoxic evaluation and these outcomes support the improvement of biological properties for complexes between Riparin A/β-cyclodextrin.

Ruthenium complexes are being considered as novel chemotherapeutic alternatives for cancer treatment. In our study, we assessed the antitumoral activities of novel ruthenium complexes coupled to the amino acids proline (RuPro) and threonine (RuThr) in prostate tumor cell lines (DU145) and breast (MCF7), and normal cell lines of the lung fibroblast (GM07492A). Our results revealed that the EC50 of the complexes for DU145 and MCF7 was two times lower than that GM07492A. Moreover, RuPro and RuThr were not able to induce significant genomic instability, cell cycle arrest or cell death in GM07492A, but could induce DNA damage, arrest in G2/M and apoptosis in DU145 and MCF7. Furthermore, BAX, TP53 and ATM were found to be upregulated in DU145 and MCF7 treated with RuPro and RuThr, in which, a higher ASCT2 gene expression was also observed. Using molecular docking, RuPro and RuThr interact with ASCT2, suggesting that this transporter might have a pivotal role in the execution of their activities. Hence, our results with RuPro and RuThr are capable of selectively inducing genetic damage, cell cycle arrest and apoptosis in DU145 and MCF7. We suggest that the selective action of the RuPro and RuThr complexes is related to the higher expression of ASCT2 in the tumor cells.

The interaction between pyrenetetrasulphonate (PTS) and methyl viologen (MV 2+ ) leads to a 1:1 charge transfer complex (CTC) in the concentration range below mmol L −1 of the ligands. Quantum mechanical calculations show the 1:1 complex having the planar moiety of PTS and the charges of the sulfonate groups stabilized by the twisted rings of the positively charged MV 2+ species. The peculiar nature of PTS includes high fluorescence quantum yield (~1), clear specular UV–vis spectra and fluorescence emission images, as well similar S 2 ←S 0 and S 3 ←S 0 transitions as those of S 1 ←S 0, all of them exhibiting well resolved vibrational structure. MV 2+ has well known electron-accepting properties that favor the complexation. These features were studied as a function of salt concentration and temperature dependences allowing a detailed comprehension of static and dynamic association processes. Quantum mechanical calculations show the 1:1 stabilization of PTS/MV 2+ . In addition the effect of urea on the CTC equilibrium is presented, as expected the additive acts towards the non-complexed species (solvated free ions). The fluorescence quenching of MV 2+ over PTS highlights is one of the applications of this effect for giant vesicles characterization.

In this work, MCM-41 were synthesized hydrothermally and functionalized with calcium and strontium salts by direct method, using the Si/M = 50 molar ratio, in order to elucidate the way as the alkaline earth is incorporated on MCM-41 molecular sieve. The materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, nitrogen adsorption–desorption and theoretical calculations by DFT method. Experimental results and computer simulations showed that the alkaline earths were incorporated on MCM-41 through a complex structure, which negatively influences on basic sites formation.

The reduction of trans- [Ru(NO)(NH 3 ) 4 (P(OEt) 3 )] 3+ ion was investigated in aqueous medium. Due to the phosphite ligand trans -effect and trans -influence, this complex selectively releases NO or HNO after one or two electrons reduction centered at the nitrosonium ligand (NO + ). These reactions were carried out through electrochemical reduction and using Eu 2+ and zinc amalgam, and the products were identified using electrochemical and spectroscopic techniques. Only the reduction of the nitrosonium ligand to nitric oxide is observed when europium is used as reductant. When the reaction is carried out with Zn(Hg), nitric oxide formation was not observed and N 2 O, an indirect marker of HNO, is detected in solution.

In this Letter, we present the investigation of the potential energy surface for the ONO–NO 2 molecule and the asymmetric dimerization of NO 2 by using the DFT/B3LYP methodology. The torsion energy of the ONO–NO 2 isomer is 1.7 kcal mol −1 . The asymmetric dimerization of NO 2 is barrierless with an energy well of 19.8 kcal mol −1 . By using the polarizable continuum model, the NO 2 asymmetric dimerization in aqueous phase may be slightly spontaneous. From this study, we suggest that this reaction is likely to occur in aqueous phase of polluted environments.