Evaluation of Chromium and Manganese levels in sports supplements using graphite furnace atomic absorption spectrometry / Avaliação do teor de Cromo e Manganês em suplementos esportivos por meio de espectrometria de absorção atômica em forno de grafite

ABSTRACT Objective In this paper, we studied three different types of ordinary sports supplements containing whey protein: whey protein-based ones, hypercaloric ones, and protein bars. Methods A sample preparation procedure was studied employing microwave-assisted wet digestion in order to determine the Chromium and Manganese levels by graphite furnace atomic absorption spectrometry. Results The developed methods have presented good accuracy (recoveries in the range of 90% to 109%) and precision (Relative standard deviation <8%). Although an adequate detectability was obtained (50ng g-1 for Manganese and 65ng g-1 for Chromium), the sample preparation method was also adequate to inductively coupled plasma mass spectrometry analysis. The method was applied to 26 commercial samples, in which the Chromium concentrations were in the range between 0.22 and 1.0μg g-1 and the Manganese concentrations varied from 2.0 to 37μg g-1. Conclusion The results obtained by atomic absorption for both analytes were in agreement with those obtained by mass spectrometry. In addition, some samples presented concentrations of Chromium above the recommended daily intake and, as a result, we used the X-ray powder diffraction technique as an analytical tool to evaluate the oxidation state of Chromium in such samples.

RESUMO Objetivo Neste trabalho, foram estudados diferentes tipos de suplementos esportivos contendo proteína de soro de leite, conhecidos como: whey protein, hipercalóricos e barras de proteína. Métodos Um procedimento de preparo de amostras foi estudado com o emprego de digestão úmida assistida por micro-ondas, a fim de determinar os teores de cromo e manganês por espectrometria de absorção atômica em forno de grafite. Resultados Os métodos adotados apresentaram boa exatidão (recuperações na faixa de 90 a 109%) e precisão (Desvio padrão relativo <8%). Embora tenha sido obtida uma capacidade de detecção adequada de 50ng g-1 para o manganês e de 65ng g-1 para o cromo, o método de preparo da amostra também se revelou adequado para a utilização em análises por espectrometria de massas com plasma indutivamente acoplado. O método foi aplicado a 26 amostras comerciais, cujas concentrações de cromo variaram entre 0,22 e 1,0μg g-1, e de manganês entre 2,0 e 37μg g-1. Conclusão Os resultados obtidos por absorção atômica, para ambos os analitos, mostraram-se de acordo com aqueles obtidos por espectrometria de massas. Além disso, algumas amostras apresentaram concentrações de cromo acima da recomendação de consumo diário e, como resultado, a técnica de difração de raios-X em pó foi utilizada como ferramenta analítica para avaliar o estado de oxidação do cromo em tais amostras.

Pro-apoptotic activity of ruthenium 1-methylimidazole complex on non-small cell lung cancer.

Herein, novel ruthenium(II) complexes containing 1-methylimidazole as a ligand were obtained with the following formulas: [RuCl(1Meim)(dppb)(bpy)]Cl (1), [RuCl(1Meim)(dppb)(4,4'-DMbpy)]Cl (2), [RuCl(1Meim)(dppb)(5,5'-DMbpy)]Cl (3) and [RuCl(1Meim)(dppb)(phen)]Cl (4) where, 1Meim = 1-methylimidazole, dppb = 1,4-Bis(diphenylphosphino)butane, bpy = 2,2'-bipyridine, 4,4'-DMbpy = 4,4'-dimethyl-2,2'-bipyridine, 5,5'-DMbpy = 5,5'-dimethyl-2,2'-bipyridine and phen = 1,10-phenanthroline. Additionally, crystal structures containing the cations of (1) and (3) were obtained when the counter ion was exchanged, leading to the formation of [RuCl(1Meim)(dppb)(bpy)]PF6 (5) and [RuCl(1Meim)(dppb)(5,5'-DMbpy)]PF6 methanol solvate (6) where PF6 = hexafluorophosphate, showing one 1-methylimidazole molecule coordinated through the imidazole nitrogen, as expected. The complexes were characterized by elemental analysis, molar conductivity, infrared and UV-Vis spectroscopy, 1H, 13C{1H} and 31P{1H} NMR, mass spectrometry and cyclic voltammetry. The interactions of complexes 1-4 with DNA and human serum albumin (HSA) were evaluated, and the cytotoxicity profiles of compounds 1-4 were determined using four different tumor cell lines derived from human cancers (melanoma: HT-144, colon: HCT-8, breast: MDA-MB-231 and lung: A549). A higher cytotoxic activity was observed for compound (3) against non-small cell lung cancer (A549). Complex (3) inhibited the clonogenic capacity and cell cycle progression of A549 cells and induced apoptosis involving mitochondrial pathway activation. Therefore, the data obtained in the present study support further investigations concerning molecular targets of complex (3) in non-small cell lung cancer.

Novel gold(I) complexes with 5-phenyl-1,3,4-oxadiazole-2-thione and phosphine as potential anticancer and antileishmanial agents.

The current anticancer and antileishmanial drug arsenal presents several limitations concerning their specificity, efficacy, costs and the emergence of drug-resistant cells lines, which encourages the urgent need to search for new alternatives. Inspired by the fact that gold(I)-based compounds are promising antitumoral and antileishmanial drug candidates, we synthesized novel gold(I) complexes containing phosphine and 5-phenyl-1,3,4-oxadiazole-2-thione and evaluated their anticancer and antileishmanial activities. Synthesis was performed by reacting 5-phenyl-1,3,4-oxadiazole-2-thione derivatives with chloro(triphenylphosphine)gold(I) and chloro(triethylphosphine)gold(I). The novel compounds were characterized by infrared, Raman, 1H, 13C nuclear magnetic resonance, high-resolution mass spectra, and x-ray crystallography. The coordination of the ligands to gold(I) occurred through the exocyclic sulfur atom. All gold(I) complexes were active at low micromolar or nanomolar range with IC50 values ranging from <0.10 to 1.66 µM against cancer cell lines and from 0.9 to 4.2 µM for Leishmania infantum intracellular amastigotes. Compound (6-A) was very selective against murine melanoma B16F10, colon cancer CT26.WT cell lines and L. infantum intracellular amastigotes. Compound (7-B) presented the highest anticancer activity against both cancer cell lines while the promising antileishmanial lead was compound (6-A). Tiethylphosphine gold(I) complexes were more active than the conterparts triphenylphosphine derivatives for both anticancer and antileishmanial activities. Triethylphosphine gold(I) derivatives presented antimony cross-resistance in L. guyanensis demonstrating their potential to be used as chemical tools to better understand mechanisms of drug resistance and action. These findings revealed the anticancer and antileishmanial potential of gold(I) oxadiazole phosphine derivatives.

Novel antitumor adamantane-azole gold(I) complexes as potential inhibitors of thioredoxin reductase.

Gold complexes that could act as antitumor agents have attracted great attention. Heterocyclic compounds and their metal complexes display a broad spectrum of pharmacological properties. The present study reports the preparation and characterization of four novel gold(I) complexes containing tertiary phosphine and new ligands 5-adamantyl-1,3-thiazolidine-2-thione, 3-methyladamantane-1,3,4-oxadiazole-2-thione. Spectroscopic data suggest that gold is coordinated to the exocyclic sulfur atom in all cases, as confirmed by X-ray crystallographic data obtained for complex (1) and supported by quantum-mechanical calculations. The cytotoxicity of the compounds has been evaluated in comparison to cisplatin and auranofin in three different tumor cell lines, colon cancer (CT26WT), metastatic skin melanoma (B16F10), mammary adenocarcinoma (4T1) and kidney normal cell (BHK-21). The gold complexes were more active than their respective free ligands and able to inhibit the thioredoxin reductase (TrxR) enzyme, even in the presence of albumin. Molecular modeling studies were carried out to understand the interaction between the compounds and the TrxR enzyme, considered as a potential target for new compounds in cancer treatment. The docking results show that the adamantane ring is essential to stabilize the ligand-enzyme complex prior the formation of covalent bond with gold center. The structure of the new gold compounds was established on the basis of spectroscopic data, DFT calculations and X-ray diffraction. TrxR inhibition was evaluated and the results correlated with the assays in tumor cells, suggesting the TrxR as possible target for these compounds.

cis-Dichloridobis-(5,5'-dimethyl-2,2'-bipyridine)-manganese(II) 2.5-hydrate.

The metal site in the title compound [MnCl(2)(C(12)H(12)N(2))(2)]·2.5H(2)O has a distorted octa-hedral geometry, coordinated by four N atoms of two 5,5'-dimethyl-2,2'-dipyridine ligands and two Cl atoms. Two and a half water molecules of hydration per complex unit are observed in the crystal structure. The compounds extend along the c axis with O-H⋯Cl, O-H⋯O, C-H⋯Cl and C-H⋯O hydrogen bonds and π-π inter-actions [centroid-centroid distance = 3.70 (2) Å] contributing substanti-ally to the crystal packing. The Mn and one of the water O atoms, the latter being half-occupied, are located on special positions, in this case a rotation axis of order 2.