Screening of the antileishmanial and antiplasmodial potential of synthetic 2-arylquinoline analogs.

In this study, six analogs of 2-arylquinoline were synthesized and evaluated for their in vitro and in vivo antiplasmodial and leishmanicidal activity. At a later stage, hemolytic activity and druggability were tested in vitro and in silico, respectively, observing as a result: firstly, compounds showed half-maximal effective concentration (EC50) values between 3.6 and 19.3 µM. Likewise, a treatment using the compounds 4a-f caused improvement in most of the treated hamsters and cured some of them. Regarding the antiplasmodial activity, the compounds showed moderate to high activity, although they did not show hemolytic activity. Furthermore, 4e and 4f compounds were not able to control P. berghei infection when administered to animal models. Molecular dynamic simulations, molecular docking and ligand binding affinity indicate good characteristics of the studied compounds, which are expected to be active. And lastly, the compounds are absorbable at the hematoencephalic barrier but not in the gastrointestinal tract. In summary, ADMET properties suggest that these molecules may be used as a safe treatment against Leishmania.

Removal of highly concentrated methylene blue dye by cellulose nanofiber biocomposites.

The contamination of water by dyes in high concentrations is a worldwide concern, and it has prompted the development of efficient, economical, and environmentally friendly materials and technologies for water purification. The hydration and adsorption capacity for methylene blue (MB) in biocomposites (BCs) based on cellulose nanofiber (CNF) (0 to 2 wt%) were studied. BCs were synthesized through a simple and straightforward route and characterized by spectroscopy, microscopic techniques and thermogravimetric analysis, among others. Hydration studies showed that BCs prepared with 2 wt% of CNF can absorb large volumes of water, approximately 2274 % in the case of poly 2-acrylamide-2-methyl-1-propanesulfonic acid (PAMPS)-CNF and 2408 % in poly sodium 4-styrene sulfonate (PSSNa)-CNF. These BCs showed outstanding adsorption capacity for highly concentrated MB solutions (4536 mg g-1 PAMPS-CNF and 11,930 mg g-1 PSSNa-CNF). It was confirmed that the adsorption mechanism is through electrostatic interactions. Finally, BCs showed high MB adsorption efficiency after several sorption-desorption cycles and on a simulated textile effluent. Furthermore, the theoretical results showed a preferential interaction between MB and the semiflexible polymer chains at the lowest energy setting. The development and study of a new adsorbent material with high MB removal performance that is easy to prepare, economical and reusable for potential use in water purification treatments was successfully achieved.

Removal of Dyes by Polymer-Enhanced Ultrafiltration: An Overview.

The current problem of contamination caused by colored industrial effluents has led to the development of different techniques to remove these species from water. One of them, polymer-enhanced ultrafiltration (PEUF), has been systematically studied in this mini review, in which research works from 1971 to date were found and analyzed. Dye retention rates of up to 99% were obtained in several cases. In addition, a brief discussion of different parameters, such as pH, interfering salts, type of polymer, dye concentration, and membrane type, and their influence in dye removal is presented. It was concluded from the above that these factors can be adapted depending on the pollutant to be remediated, in order to optimize the process. Finally, theoretical approaches have been used to understand the intermolecular interactions, and development of the studied technique. In this revision, it is possible to observe that molecular docking, molecular dynamics simulations, density functional theory calculations, and hybrid neural-genetic algorithms based on an evolutionary approach are the most usual approximations used for this purpose. Herein, there is a detailed discussion about what was carried out in order to contribute to the research development of this important science field.

A theoretical chemistry-based strategy for the rational design of new luminescent lanthanide complexes: an approach from a multireference SOC-NEVPT2 method.

Theoretical methods of the SOC-NEVPT2 type combined with a molecular fragmentation scheme have been proven to be a powerful tool that allows explaining the luminescence sensitization mechanism in Ln(III) coordination compounds through the antenna effect. In this work, we have used this strategy to predict luminescence in a family of compounds of the Eu(R-phen)(BTA)3 type where R-phen = 5-methyl-1,10-phenanthroline (Me-phen), 5-nitro-1,10-71 phenanthroline (Nitro-phen), 4,5-diazafluoren-9-one (One-phen), or 5,6-epoxy-5,6-dihydro-1,10-72 phenanthroline (Epoxy-phen); and BTA = fluorinated ß-diketone. Possible sensitization pathways were elucidated from the energy difference between the ligand-centered triplet (3T) states and the emissive excited states of the Eu(III) fragments (Latva rules). Calculations show that the most probable mechanism occurs through the triplet state of the BTA which should be enriched by several parallel energy transfer pathways from R-phen substituents. The complexes were synthesized and structurally characterized by X-ray crystallography and various other physicochemical and spectroscopic methods to realize their optical properties and energy transfer pathways from dual antennae. Experimental results were in good agreement with the theoretical predictions, which reinforces the predictive power of the used theoretical methodology.

Combining edible coatings technology and nanoencapsulation for food application: A brief review with an emphasis on nanoliposomes.

The use of bioactive compounds within the biopolymer-based Edible Coatings (EC) matrices has certain limitations for their application at the food industry level. Encapsulation has been considered as a strategy that enables protecting and improving the physical and chemical characteristics of the compounds; as a result, it extends the shelf life of coated foods. This review discusses recent progress in combining edible coatings with nanoencapsulation technology. We also described and discussed various works, in which nanoliposomes are used as encapsulation systems to prepare, and subsequently apply the edible coatings in plant products and meat products. The use of nanoliposomes for the encapsulation of phenolic compounds and essential oils provides an improvement in the antioxidant and antimicrobial properties of coatings by extending the shelf life of food matrices. However, when liposomes are stored for a long period of time, they may present some degree of instability manifested by an increase in size, polydispersity index, and zeta potential. This is reflected in an aggregation, fusion, and rupture of the vesicles. This investigation can help researchers and industries to select an appropriate and efficient biopolymer to form EC containing nanoencapsulated active compounds. This work also addresses the use of nanoliposomes to create EC extending markedly the shelf life of fruit, reducing the weight loss, and deterioration due to the action of microorganisms.

Structural Characterization, DFT Calculation, NCI, Scan-Rate Analysis and Antifungal Activity against Botrytis cinerea of (E)-2-{[(2-Aminopyridin-2-yl)imino]-methyl}-4,6-di-tert-butylphenol (Pyridine Schiff Base).

Botrytis cinerea is a ubiquitous necrotrophic filamentous fungal phytopathogen that lacks host specificity and can affect more than 1000 different plant species. In this work, we explored L1 [(E)-2-{[(2-aminopyridin-2-yl)imino]-methyl}-4,6-di-tert-butylphenol], a pyridine Schiff base harboring an intramolecular bond (IHB), regarding their antifungal activity against Botrytis cinerea. Moreover, we present a full characterization of the L1 by NMR and powder diffraction, as well as UV-vis, in the presence of previously untested different organic solvents. Complementary time-dependent density functional theory (TD-DFT) calculations were performed, and the noncovalent interaction (NCI) index was determined. Moreover, we obtained a scan-rate study on cyclic voltammetry of L1. Finally, we tested the antifungal activity of L1 against two strains of Botrytis cinerea (B05.10, a standard laboratory strain; and A1, a wild type strains isolated from Chilean blueberries). We found that L1 acts as an efficient antifungal agent against Botrytis cinerea at 26 °C, even better than the commercial antifungal agent fenhexamid. Although the antifungal activity was also observed at 4 °C, the effect was less pronounced. These results show the high versatility of this kind of pyridine Schiff bases in biological applications.

Effect of lyophilization on the physicochemical and rheological properties of food grade liposomes that encapsulate rutin.

The potential use of liposomes as carriers for food active ingredients can be limited by their physical and chemical instabilities in aqueous dispersions, especially for long-term storage. Lyophilization, a process commonly used in the food industry, can also be applied to stabilize and preserve liposomes and to extend their shelf-life. In this work, liposomes with potential use for designing functional foods were prepared with soy phospholipids and rutin. Homogenization and ultrasound were used for particle size reduction. Liposomal stability was evaluated by Dynamic Light Scattering, microscopy and rheological properties. Spherical and unilamellar liposomes were obtained in this work. Zeta potential (ξ = values were around -40 mV), which indicates a great suspension stability even for more than 30 days of storage. Rutin exerted a protective effect by both preventing damage to the liposome bilayer and maintaining the spherical structure after 56 days of storage. Lyophilization caused an increase in the size of the vesicles, reaching sizes around 419 nm and aggregation of vesicles with probably structural damage after 21 storage days. However, it helped to keep the rutin encapsulated (81.9%) for longer time, when compared to refrigerated liposomes. Rheological measurements showed, in general, that the power law model fitted most of the experimental results and dynamic rheological tests showed a sol-gel phase transition between 35 and 45 °C. Lyophilization caused a significant change in all evaluated rheological parameters. For the in vitro release tests, the liposomal bilayer acted as a barrier for the rutin release to the food simulating medium; therefore, the release rate of the antioxidant from the rutin encapsulated liposome was slow compared to the free rutin release rate.

Classical and Quantum Mechanical Calculations of the Stacking Interaction of NdIII Complexes with Regular and Mismatched DNA Sequences.

The design of organometallic complexes used as selective intercalators to bind and react at DNA mismatch sites has concentrated efforts in the last few years. In this context, lanthanides have received attention to be employed as active optical centers due to their spectroscopic properties. Despite the fact that there are several experimental data about synthesis and DNA binding of these compounds, theoretical analyses describing their interaction with DNA are scarce. To understand the binding to regular and mismatched DNA sequences as well as to determine the effect of the intercalation on the spectroscopic properties of the complexes, a complete theoretical study going from classical to relativistic quantum mechanics calculations has been performed on some lanthanide complexes with phenanthroline derivatives synthesized and characterized herein, viz. [Nd(NO3)3(H2O)(dppz-R)] with R = H, NO2-, CN- and their [Nd(NO3)3(H2O)(dpq)] analogue, which was computationally modeled. The results were in correct agreement with the available experimental data showing that dppz complexes have higher binding affinities to DNA than dpq one and supporting the idea that these complexes are not selective to mismatch sites in the sampled time scale. Finally, the spectroscopic analysis evidence an intercalative binding mode and made possible the elucidation of the emission mechanism of these systems. This approach is proposed as a benchmark study to extend this methodology on similar systems and constitutes the first theoretical insight in the interaction between DNA and lanthanide complexes.

Theoretical Method for an Accurate Elucidation of Energy Transfer Pathways in Europium(III) Complexes with Dipyridophenazine (dppz) Ligand: One More Step in the Study of the Molecular Antenna Effect.

A theoretical protocol to study the sensitization and emission mechanism in lanthanide compounds on the basis of multireference CASSCF/PT2 calculations is proposed and applied to [Eu(NO3)3(dppz-CN)] and [Eu(NO3)3(dppz-NO2)] compounds synthesized and characterized herein. The method consists of a fragmentation scheme where both the ligand and the lanthanide fragments were calculated separately but at the same level of theory, using ab initio wave-function-based methods which are adequate for the treatment of quasi-degenerate states. This is based on the fact that the absorption is ligand-localized and the emission is europium-centered. This characteristic allowed us to describe the most probable energy transfer pathways that take place in the complexes, which involved an ISC between the S1 to T1 ligand states, energy transfer to 5D2 in the lanthanide fragment, and further 5D0 → 7FJ emission. For both compounds, the triplet and 5D2 states were determined at the CASPT2 level to be around ∼26000 and ∼22400 cm-1, respectively. This difference is in the optimal range for the energy transfer process. Finally, the emissive state 5D0 was found at ∼18000 cm-1 and the emission bands in the range 550-700 nm, in quite good agreement with the experimental results.

The role of the [CpM(CO)2](-) chromophore in the optical properties of the [Cp2ThMCp(CO)2](+) complexes, where M = Fe, Ru and Os. A theoretical view.

The chemical bond between actinide and the transition metal unsupported by bridging ligands is not well characterized. In this paper we study the electronic properties, bonding nature and optical spectra in a family of [Cp2ThMCp(CO)2](+) complexes where M = Fe, Ru, Os, based on the relativistic two component density functional theory calculations. The Morokuma-Ziegler energy decomposition analysis shows an important ionic contribution in the Th-M interaction with around 25% of covalent character. Clearly, charge transfer occurs on Th-M bond formation, however the orbital term most likely represents a strong charge rearrangement in the fragments due to the interaction. Finally the spin-orbit-ZORA calculation shows the possible NIR emission induced by the [FeCp(CO)2](-) chromophore accomplishing the antenna effect that justifies the sensitization of the actinide complexes.