Aníbal de Freitas Santos Júnior

Determinação de Mn, Cu e Zn em matrizes salinas após separação e pré-concentração usando Amberlite XAD-7 impregnada com Vermelho de Alizarina S

The aim of this work was to explore the possibility of the application of a non-ionic resin obtained by impregnation of Alizarin Red S (VAS) in Amberlite XAD-7 for manganese, copper and zinc separation and preconcentration in saline matrices. For these system, the metals were quantitatively retained, in the pH range 8.5-10.0, by using 0.50 g of solid phase, stirring time of five minutes and a total mass up to 200 mg of each cation. The sorbed elements were subsequently eluted and a fifty-fold, ten-fold and ten-fold preconcentration factor for to Zn, Cu and Mn were obtained, respectively.

Multielement Determination of Macro and Micro Contents in Medicinal Plants and Phytomedicines from Brazil by ICP OES

In this study, the elemental composition of nine medicinal plants and phytomedicines was evaluated by using axial view inductively coupled plasma optical emission spectrometry (ICP OES) after three digestion procedures: dry ashing (DA) and two wet digestions with a mineral acid (HNO3/H2O2) mixture on a conventional hot plate (CD), besides microwave digestion (MW). Accuracy was assessed from spinach leaves (CRM 1570a) and recovery values were in the range of 82 to 113.8%. Precisions, such as relative standard deviation (RSD), below 10% were reached. The MW procedure was preferred for its accuracy (recovery values of 94 to 102%), reduced contamination, increase in the efficiency of the decomposition process, lower residual acidity and reduced time required for digestion. The concentrations of analytes in the samples (minimum-maximum in μg g-1) were: Ca (100.71-462.20), Co (0.54-0.85), Cu (0.32-7.82), Fe (2.74-18.03), Mg (18.40-521.28), Mn (0.17-55.14), Ni (0.56-1.25) and Zn (2.96-20.92). The levels of Al, Ba, Cd, Cr, Mo, Pb, Se and V in all investigated samples were found to be below the limit of detection of ICP OES. The multielement analysis by ICP OES showed that the method is simple, fast and reliable for the multielement determination in medicinal plants and phytomedicines.

Analytical Strategies for Determination and Environmental Impact Assessment of Inorganic Antimony Species in Natural Waters Using Hydride Generation Atomic Fluorescence Spectrometry (HG AFS)

This study proposes an optimized procedure for the determination of inorganic antimony species in natural waters using hydride generation atomic fluorescence spectrometry (HG AFS) and continuous flow system. The variables of the hydride generation system, such as pre-reduction time, hydrochloric acid concentration and sodium tetrahydroborate concentration, were evaluated using full factorial design at two levels and Doehlert design. After optimized experimental conditions, the method allowed the determination of antimony with limits of detection and quantification of 9 and 30 ng L, respectively. The precision (RSD) of the method was < 5% and the accuracy was confirmed by the analysis of certified reference material (SLRS-4, River water for trace metals). The method was successfully applied for inorganic antimony speciation in water samples collected in Salvador City, Bahia State, Brazil. In mineral water, total Sb concentrations ranged from 0.26 to 0.30 μg L, whereas the concentrations of Sb were below 0.03 μg L. On the other hand, in natural surface waters, the quantifiable concentration of total Sb and Sb ranged from 0.41 to 1.23 μg L and 0.23 to 1.04 μg L, respectively. The highest average concentrations of Sb were obtained in regions with the largest urban influence, ratifying the anthropogenic impact in water bodies.

Multielementar/centesimal composition and determination of bioactive phenolics in dried fruits and capsules containing Goji berries (Lycium barbarum L.)

The elemental/centesimal composition of dried fruits and capsules containing Goji berries (Lycium barbarum L.) was evaluated by ICP OES after two digestion procedures. Furthermore, phenolic acid compounds and flavonoids were quantified by HPLC-UV-DAD. Precision, accuracy, LOD and LOQ were evaluated. The samples showed similar contents of proteins, lipids and carbohydrates. The metal contents in the samples were found at different levels (minimum-maximum, in mg kg-1), as follows: Ca (181.1-200.2); Cu (1.703-2.145); Fe (7.420-7.852); K (81.78-83.59); Mg (92.58-95.12); Mn (1.630-2.570); Na (587.9-590.7); P (3.124-3.360); Se (2.812-3.345); V (0.055-0.062) and Zn (2.325-2.610). Al, As, Ba Cd, Co, Ni, P, Pb, Sb, Sn and Sr showed values below the LOD. Accuracy was assessed by analysis of tomato leaves (NIST 1573a). Eight bioactive phenolic compounds (caffeic, chlorogenic, ellagic, ferulic, gallic, p-coumaric, syringic and vanillic acids) and two flavonoids [(+)-catequin and rutin] were determined, in levels of 55.5-83.700 and 172.3-2982.4 mg kg-1, respectively.

Virtual Screening for the Selection of New Candidates to Trypanosoma cruzi Farnesyl Pyrophosphate Synthase Inhibitors

Chagas disease is a tropical parasitic disease that is caused by Trypanosoma cruzi and causes 12,000 deaths per year, mainly in Latin America. The available drugs for treating have severe limitations, including poor efficacy and high toxicity. One way to overcome these limitations is targeting priority molecules with computational tools to direct in vitro assays against validated targets. Farnesyl pyrophosphate synthase (E.C. 2.5.1.10) is an enzyme that participates in the initial stage of sterol biosynthesis, and its inhibition causes damage to membrane integrity, leading to parasite death. With the aim to identify potential inhibitors against this target from T. cruzi, hierarchical virtual screening approaches were performed through a combination of ligand-based pharmacophore models and molecular docking. First, pharmacophore model filtering resulted in 15,154 molecules that had the minimum structural requirements for inhibition (QFIT > 0). These molecules were subsequently submitted to molecular docking routine, which resulted in 11,762 molecules (Grid Score between –232.74 to –0.96 kcal mol). The top 30 ranked molecules in these approaches were grouped in self-organizing maps. These analyses showed four promising compounds from natural products that mimic the major interactions present in the substrate/ inhibitor, which indicates that these molecules can be assayed by in vitro experiments.

Effects of furosemide administration on the concentration of essential and toxic elements in Wistar rats by inductively coupled plasma optical emission spectrometry

Furosemide can interfere with the metabolism of chemical elements, changing their levels in several tissues, thus causing imbalance. In this study, inductively coupled plasma optical emission spectrometry (ICP OES) was used for multi-element analysis (Cd, Cu, Fe, Mg, Pb, Se and Zn) after microwave-assisted digestion, to evaluate the effect of furosemide (loop diuretic) on the composition of these essential and toxic elements in biological samples (liver, kidney, heart, lung and serum) of Wistar rats. Male and female Wistar rats (n = 40, 180-350 g) were randomly divided into 2 groups (n = 20/group). The results were expressed as μg/g dry weight. The mean tissue concentrations (minimum-maximum in μg/g) of Cu, Fe, Mg and Zn in the biological samples ranged between 5.2 and 1023.5. The levels of Cd, Pb and Se were below the detection limit of the ICP OES. Accuracy was assessed by microwave-assisted digestion and recovery values of 83-116% were obtained. Liver had significantly higher trace element concentrations in most of the analyzed samples. Mg showed a significant reduction (for males and females) in its levels in the heart. In both genders, there was similarity in the Cu concentration reduction (around 16%) for all tissues. The highest iron losses were found for serum (52% and 12%) for male and female rats, respectively. Reductions in Zn occurred between 0.3 and 18.0%, mainly for kidneys and heart, respectively. This study demonstrated that furosemide altered the concentration of some elements in rats.