The luminescent Chalcones. Its potential use as a luminescent and antitumoral agents / Chalconas luminiscentes. Su uso potencial como agentes luminiscentes y antitumorales

Background: Hepatocellular carcinoma (HCC) is one of the most diagnosed cancers worldwide. Chemoprevention of HCC can be achieved using natural or synthetic compounds that reverse, suppress, detect, or prevent cancer progression. Objectives: In this study, both the antiproliferative effects and luminescent properties of 2'-hydroxychalcones were evaluated. Methods: Cell viability was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay, spectroscopy assays, and density functional theory (DFT) calculations were used to determine the luminescent properties of 2 ́-hydroxychalcones. Results: Cytotoxic effects of 2 ́-hydroxychalcones were observed over the HepG2 and EA.hy926 cells. Since the chalcone moiety could be used as a fluorescent probe, these compounds may be helpful in cancer diagnosis and tumor localization. They may enable tumor observation and regression through the fluorescence during treatment; therefore, the compounds are a potential candidate as novel anticancer agents acting on human hepatomas. Conclusions: This report describes the chalcones' use as a specific luminescent biomarker in tumor cells. We also report the cellular uptake of 2'-hydroxychalcones, their cellular distribution, and the mechanisms that may be responsible for their cytotoxic effects

ANTECEDENTES: El carcinoma hepatocelular (CHC) es uno de los cánceres más diagnosticados en todo el mundo. La quimio prevención del CHC se puede lograr utilizando compuestos naturales o sintéticos que reviertan, supriman, detecten o prevengan la progresión del cáncer. OBJETIVOS: En este estudio, se investigó tanto los efectos antiproliferativos como las propiedades luminiscentes de las 2'-hidroxicalconas. MÉTODOS: La viabilidad celular se evaluó usando el ensayo colorimétrico (MTT), los ensayos de espectroscopia y los cálculos DFT se usaron para determinar las propiedades luminiscentes de las 2 ́-hidroxichalconas. RESULTADOS: Se observaron efectos citotóxicos sobre las líneas celulares del tipo HepG2 y EA.hy926. Dado que la estructura de la 2 ́-hidroxichalcona puede ser usada como sonda fluorescente, estos compuestos pueden ser útiles en el diagnóstico del cáncer y la localización del tumor, ya que pueden permitir la observación a través de la fluorescencia y la regresión del tumor durante el tratamiento, por lo que son candidatas potenciales como nuevos agentes anticancerígenos que podrían actuar sobre hepatomas humanos. CONCLUSIONES: Este trabajo describe el uso de las 2 ́-hidroxichalconas como un biomarcador luminiscente específico para células tumorales. También informamos la captación celular de 2>-hidroxicalconas, su distribución celular y los mecanismos que pueden ser responsables de sus efectos citotóxicos

Cluster of Hexamolybdenum [Mo6Cl14]2- for Sensing Nitroaromatic Compounds.

This contribution describes a novel method for the detection of trace amounts of trinitrotoluene (TNT) using a cluster of hexamolybdenum with general formula [Mo6Cl14]2-. The molybdenum cluster was characterized by UV-visible, FT-IR, and fluorescence techniques, and the synthesis was efficient and reproducible. The evaluation of the molybdenum cluster by TNT detection was perfomed by fluoresecent measurements, and the results were interpreted by the Stern-Volmer equation, obtaining K SV values of 2.9 × 105 and 1.6 × 104 M-1 in different concentration ranges. Further, the results suggest that at TNT concentrations higher than 4 × 10-5 mM (0.01 mg L-1) it is possible to measure the quenching of the cluster fluorescence. The DFT calculations indicate that the contribution of the TNT in the active lowest unoccupied molecular orbitals that are involved in the higher intensity transitions in the complex cluster-TNT are significant. This situation differs from all the luminescent [M6X8L6]2- clusters (M = Mo; X = facial bridging ligand, and L = labile axial ligands), where most of the closely spaced excited states are located in the {M6X8} q+ core. Thus, the TNT switches off the cluster luminescence. The approach using a [Mo6Cl14]2--based fluorescence sensor has the potential to be a sensing technology for the detection of nitroaromatic explosives.

Imogolite Synthetized in Presence of As(III) Induces Low Cell Toxicity and Hemolysis, in Vitro, Potential Stabilization of Arsenite Present in Aqueous Systems.

Imogolite is a nanotubular aluminosilicate that has low toxicity in biological systems and due to its morphological and surface properties has a growing interest in environmental applications and biomedical areas. Its synthesis is highly sensitive to the presence of other ions, being able to inhibit or retard the process of imogolite formation, which could change the cytotoxic response of this substrate, something scarcely reported in the literature. In this context, the presence of arsenite during the synthesis of imogolite caused significant changes in the dimensions and surface behavior of these nanotubes. Cell viability was evaluated on EA.hy926 and HepG2 cells by (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide) assay at 24 h. Meanwhile, the potential effects on human red blood cells, namely, hemolysis and morphological changes, were determined at 0 and 24 h. The range of % As tested of the nanotube showed cell toxicity similar to the control condition. Similarly, the As-based nanotubes induced hemolysis similar to controls and slight morphological changes of red blood cells at 0 and 24 h of exposition. These results indicate that As-based imogolite-like nanotubes are not toxic nor hemolytic and can be potentially used in processes like water purification.

Relativistic effects on the aromaticity of the halogenated benzenes: C6X6, X = H, F, Cl, Br, I, At.

In this study we report about the relativistic effects on the aromaticity of the six hexahalogenated compounds (C6H6, C6F6, C6Cl6, C6Br6, C6I6 and C6At6), via a magnetically induced current density method. All-electron density functional theory (DFT) calculations were carried out using the four-component Dirac-Coulomb (DC) Hamiltonian, including scalar and spin-orbit (SO) relativistic effects. Fully relativistic values of the magnetically induced ring currents were obtained by numerical integration over the current flow. These values were compared to the spin-free (SO interaction switched off) and non-relativistic values, in order to assess the corresponding contributions to aromaticity. It was found that in C6I6 and C6At6 there is a strong SO influence, in line with the expected relativistic effects of the heavy elements, iodine and astatine.

A Theoretical Study of the Binding of [Re6Se8(OH)2(H2O)4] Rhenium Clusters to DNA Purine Base Guanine.

Hexanuclear rhenium complexes are promising candidates for use as antitumor drugs. However, to date, there has been no investigation into the nature of their binding to DNA. In this study, density functional theory (DFT) was used to examine the binding of [Re6Se8(OH)2(H2O)4] to the DNA purine base guanine. The geometrical structures of cluster-guanine adducts in water were modeled at the zero order regular approximation (ZORA)-PW91 level. Calculating the bond energies allowed us to compare the cis and trans forms of the cluster, and a possible manners of interaction between [Re6Se8(OH)2(H2O)3] clusters and DNA was obtained and explained.

Probing the aromaticity of the [(H(t)Ac)3(µ2-H)6], [(H(t)Th)3(µ2-H)6],(+), and [(H(t)Pa)3(µ2-H)6] clusters.

In this study we report about the aromaticity of the prototypical [(H(t)Ac)(3)(µ(2)-H)(6)], [(H(t)Th)(3)(µ(2)-H)(6)](+), and [(H(t)Pa)(3)(µ(2)-H)(6)] clusters via two magnetic criteria: nucleus-independent chemical shifts (NICS) and the magnetically induced current density. All-electron density functional theory calculations were carried out using the two-component zeroth-order regular approach and the four-component Dirac-Coulomb Hamiltonian, including scalar and spin-orbit relativistic effects. Four-component current density maps and the integration of induced ring-current susceptibilities clearly show that the clusters [(H(t)Ac)(3)(µ(2)-H)(6)] and [(H(t)Th)(3)(µ(2)-H)(6)](+) are non-aromatic whereas [(H(t)Pa)(3)(µ(2)-H)(6)] is anti-aromatic. However, for the thorium cluster we find a discrepancy between the current density plots and the classification through the NICS index. Our results also demonstrate the increasing influence of f orbitals, on bonding and magnetic properties, with increasing atomic number in these clusters. We think that the enhanced electron mobility in [(H(t)Pa)(3)(µ(2)-H)(6)] is due the significant 5f character of its valence shell. Also the participation of f orbitals in bonding is the reason why the protactinium cluster has the shortest bond lengths of the three clusters. This study provides another example showing that the magnetically induced current density approach can give more reliable results than the NICS index.

Spin-orbit effects on the aromaticity of the Re3X9(2-) (X = Cl, Br) cluster ions.

In our recent article (Chem. Phys. Lett. 2008, 467, 94-96), we reported the aromaticity via NICS calculations of the neutral Re(3)Cl(9) and Re(3)Br(9) clusters. Spin-orbit effects decrease their aromaticity due to the fact that the 5d(3/2) spinors are mostly occupied and are more contracted than the scalar 5d orbitals. Here, we report that the title anions are also aromatic but, oppositely, spin-orbit effects increase the clusters' aromaticity due to the fact that the 5d(5/2) spinors are now being populated and are more expanded than the scalar 5d orbital. All the clusters discussed here have larger induced diatropic ring currents than benzene.