João B. Pereira Junior

Clinical Oxidative Stress during Leprosy Multidrug Therapy: Impact of Dapsone Oxidation

This study aims to assess the oxidative stress in leprosy patients under multidrug therapy (MDT; dapsone, clofazimine and rifampicin), evaluating the nitric oxide (NO) concentration, catalase (CAT) and superoxide dismutase (SOD) activities, glutathione (GSH) levels, total antioxidant capacity, lipid peroxidation, and methemoglobin formation. For this, we analyzed 23 leprosy patients and 20 healthy individuals from the Amazon region, Brazil, aged between 20 and 45 years. Blood sampling enabled the evaluation of leprosy patients prior to starting multidrug therapy (called MDT 0) and until the third month of multidrug therapy (MDT 3). With regard to dapsone (DDS) plasma levels, we showed that there was no statistical difference in drug plasma levels between multibacillary (0.518±0.029 µg/mL) and paucibacillary (0.662±0.123 µg/mL) patients. The methemoglobin levels and numbers of Heinz bodies were significantly enhanced after the third MDT-supervised dose, but this treatment did not significantly change the lipid peroxidation and NO levels in these leprosy patients. In addition, CAT activity was significantly reduced in MDT-treated leprosy patients, while GSH content was increased in these patients. However, SOD and Trolox equivalent antioxidant capacity levels were similar in patients with and without treatment. These data suggest that MDT can reduce the activity of some antioxidant enzyme and influence ROS accumulation, which may induce hematological changes, such as methemoglobinemia in patients with leprosy. We also explored some redox mechanisms associated with DDS and its main oxidative metabolite DDS-NHOH and we explored the possible binding of DDS to the active site of CYP2C19 with the aid of molecular modeling software.

An antioxidant mechanism of morphine and related derivatives

A structural and computational study of the morphine mechanism as an antioxidant or oxidant compound is performed by density functional theory (DFT) calculations. The geometry was obtained using the B3LYP/6-31G(d,p) method. The antioxidant property of morphine is related to the highest occupied molecular orbital (HOMO) energy, ionization potential (IP), stabilization energy (ΔΕiso), bond dissociation energy (BDE), and spin density distribution for the electron abstraction at the amine position, which is more favored than other positions for morphine. The decrease in the HOMO and IP values, together with the increase in the ΔΕiso values, is related to amine groups, ether and alkyl moieties, benzene rings, hydroxyls, and double bonds. The hydrogen abstraction in the phenol position is more favored than the other positions in morphine. The prevalent spin contribution for these groups is important for the highest stability free radical and other resonance structures. Morphine is more powerful antioxidant than its de-methylated or hydroxylated derivatives.

Studying the distribution of Selenium in buffalo and cow's milk whey

In this study, size exclusion chromatography (SEC) coupled with an online ultraviolet detection (UV) and graphite furnace atomic absorption spectrometry (GF AAS) and matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) were used to study the association of selenium with macromolecules and compounds present in buffalo and cows milk whey. SEC-UV profiles obtained from buffalo and cows milk whey samples indicate the presence of high molecular weight (HMW) and low molecular weight (LMW) species in both samples studied. The combined information obtained with SEC-UV, GF AAS and MALDI-TOF-MS for fractions < 10 kDa confirmed the association of selenium with LMW species

Mineral Composition of Amazonian Fruits by Flame Atomic Absorption Spectrometry Using Multivariate Analysis

This study aimed to evaluate the mineral composition in native and non-native Amazonian fruits using flame atomic absorption spectrometry (FAAS) and multivariate methods, such as principal component analysis (PCA) and hierarchical cluster analysis (HCA), in order to conduct a more thorough evaluation of the original data. The accuracy was checked by certified reference material analysis (Poplar leaves) and spike experiments. The results of the analysis were in agreement with the certified values, with analytical recoveries for all analytes in an acceptable range from 82 to 113%, and relative standard deviations (RSD) were in the range of 0.2–18%. Furthermore, PCA explained 68% of the total variance, while HCA confirmed the correlations found in the PCA, allowing for the evaluation of the degree of similarity between the fruits studied. These results will be used to better understand the distribution of inorganic constituents within these Amazonian fruits.

Avaliação da Concentração de Elementos-traço em Farinha de Mandioca ( Manihot esculenta Crantz) por Espectrometria de Emissão Óptica com Plasma Acoplado Indutivamente

As concentracoes de Ca, Cu, Fe, K, Mg, Mn, P e Zn em 10 amostras de farinha de mandioca comercialmente disponiveis ( Manihot esculenta Crantz, Euphorbiaceae) foram analisadas por espectrometria de emissao optica com plasma acoplado indutivamente (ICP OES). Os elementos foram encontrados em ordem decrescente de concentracao, como Ca > P > Mg > Fe > Cu > Zn > Mn. Com base na ingestao diaria recomendada para adultos, os valores mostraram que o consumo de 10 g de farinha de mandioca por dia proporciona 5,3% da ingestao diaria para Cu, 0,5-1,2% para Fe, 0,5% para Ca, 0,9-1,2% para Mg, 0,6 -0,8% para Mn, 0,6% para P, 0,2% para K e 0,2-0,3% para Zn. Os resultados indicam que a farinha de mandioca contem varios elementos essenciais e nao apresenta riscos a saude humana.As concentracoes de Ca, Cu, Fe, K, Mg, Mn, P e Zn em 10 amostras de farinha de mandioca comercialmente disponiveis ( Manihot esculenta Crantz, Euphorbiaceae) foram analisadas por espectrometria de emissao optica com plasma acoplado indutivamente (ICP OES). Os elementos foram encontrados em ordem decrescente de concentracao, como Ca > P > Mg > Fe > Cu > Zn > Mn. Com base na ingestao diaria recomendada para adultos, os valores mostraram que o consumo de 10 g de farinha de mandioca por dia proporciona 5,3% da ingestao diaria para Cu, 0,5-1,2% para Fe, 0,5% para Ca, 0,9-1,2% para Mg, 0,6 -0,8% para Mn, 0,6% para P, 0,2% para K e 0,2-0,3% para Zn. Os resultados indicam que a farinha de mandioca contem varios elementos essenciais e nao apresenta riscos a saude humana.

Study of the Distribution of Metals in Tissues of Fish from Amazon Region

The purpose of this study was to evaluate the levels of Al, Ca, Cu, Fe, Mg, Mn, Na, Pb and Zn in 15 samples of five fish species (Brachyplatystoma rousseauxii, Brachyplatystoma filamentosum, Cynoscion leiarchus, Brachyplatystoma vaillanti e Colossoma macropomum) obtained in municipal market of Belém (Pará State, Brazil). These samples were digested in a cavity microwave oven using a 3.5 mol L nitric acid solution and concentrated hydrogen peroxide. Total concentrations of the studied elements were determined by flame atomic absorption spectrometry (FAAS) and graphite furnace atomic absorption spectrometry (GF AAS). The contents of the elements in fish samples ranged from 90.12-2497.09 μg g for Al, 114.05-7100.10 μg g for Ca, 43.2-150.1 μg g for Cu, 22.26-4296.62 μg g for Fe, 514.03-7520.13 μg g for Mg, 20.05-20.08 μg g for Mn, 227.93-7315.56 μg g for Na, 0.54-11.81 μg g for Pb, and 7.46-129.74 μg g for Zn. Results show that higher levels of the elements studied were found in the liver and lower levels in the muscle of fish. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were applied to check correlations between mineral composition, length and mass of fish samples studied.

Biomonitoring of Metallic Elements in Freshwater Fish of Amazon

The monitoring of aquatic environments through bioindicators use has been the object of study in several recent works, mainly due to concern over the harmful effects of metallic element levels may cause to aquatic organisms, moreover, and to the risks related with the human consumption of contaminated food. It was measured o te ts of C , Fe a d Z i fish s us les a d gills of seve spe ies of the A azo egio , olle ted i Pi aí a s ive situated in Icoaraci district, Belém – Pará. For quantification of Cr it was used a graphite furnace atomic absorption spectrometry (GF AAS) and for quantification for Fe and Zn was used flame atomic absorption spectrometry (FAAS) e uip e t. The ethod s validation was developed through of the method of adding and recovery. The contents of Cr obtained were (< 0.19 – 4.93 μg g) in muscles, for gills (0.20 – 206.50 μg g), for Fe element in the muscle (< 8.00 – 27.00 μg g), in gills (< 8.00 – 2130.33 μg g), for Zn were obtained (8.93 – 42.39 μg g) and in gills (31.30 – 282.36 μg g). In the data analysis it was calculated the tolerable weekly ingestion index for the three mineral components; for that, it was applied Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA). The results obtained for Cr exceeded limits established by Brazilian Health Surveillance Agency (ANVISA) for human consumption both in muscles and gills. The Zn contents did not exceed values established for muscles and exceed for gills and for Fe the high concentrations were obtained in gills.