Artigos Científicos - FAQUI/ICEN
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Item Acesso aberto (Open Access) Phytotoxic potential of the geopropolis extracts of the jandaira stingless bee (Melipona Subnitida) in weeds(Universidade Federal do Pará, 2017-12) PEREIRA, Daniel Santiago; HOLANDA NETO, João Paulo de; OLIVEIRA, Mozaniel Santana de; PEREIRA, Natanael Santiago; MARACAJÁ, Patrício Borges; SOUZA FILHO, Antonio Pedro da SilvaThe objective of the present research is to characterize the phytotoxic activity of geopropolis from the Jandaira bee (Melipona subnitida Ducke) in the state of Ceará in Northeast Brazil and to analyze its effects. Extracts were prepared in 80% v/v grain alcohol at 0.25, 0.5, 0.75, and 1.0%. Their effects were determined on seed germination, radicle elongation, and hypocotyl growth of the pasture weeds malícia (Mimosa pudica) and mata-pasto (Senna obtusifolia). Extract phytotoxicity varied as functions of plant species, application dosage, and plant organ. M. pudica was more sensitive to the inhibitory effects of geopropolis than S. obtusifolia. There was a phytotoxic effect of 50% (PE50) for S. obtusifolia in terms of seed germination and in rootlet development near the maximum applied concentrations. M. pudica had PE50 and PE90 at the minimum concentration (0.25%) and near the maximum (1.00%), respectively. Thus, geopropolis extracts from the Jandaira bee (M. subnitida) are potentially phytotoxic to certain plant species.Item Acesso aberto (Open Access) Triterpenoides, fenólicos e efeito fitotóxico das folhas de Eugenia flavescens DC (Myrtaceae)(Universidade Federal do Pará, 2017-04) CANTANHEDE FILHO, Antonio José; SANTOS, Lourivaldo da Silva; GUILHON, Giselle Maria Skelding Pinheiro; ZOGHBI, Maria das Graças Bichara; PORT'S, Pollyane da SilvaItem Acesso aberto (Open Access) Annularins I and J: New Metabolites Isolated from Endophytic Fungus Exserohilum rostratum(Universidade Federal do Pará, 2016-08) PINHEIRO, Eduardo Antonio Abreu; BORGES, Fábio Cardoso; PINA, Jeferson Rodrigo Souza; FERREIRA, Leila do Remédio Santos; CORDEIRO, Jorgeffson da Silva; CARVALHO, Josiwander Miranda; FEITOSA, André de Oliveira; CAMPOS, Francinete Ramos; BARISON, Andersson; SOUZA, Afonso Duarte Leão de; MARINHO, Patrícia Santana Barbosa; MARINHO, Andrey Moacir do RosárioThe paper describes the isolation of ergosterol peroxide, monocerin, annularin I and annularin J compounds of Exserohilum rostratum biomass extracts. Compounds were isolated by silica gel column chromatography in polarity gradient and the structures were determined by nuclear magnetic resonance (NMR) and mass spectrometry (MS) methods. Monocerin, annularin I and annularin J compounds were tested against Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis bacteria and showed moderate activity. Annularin I and annularin J compounds are new natural products.Item Acesso aberto (Open Access) Estudos farmacognósticos, fitoquímicos, atividade antiplasmódica e toxicidade em Artemia salina de extrato etanólico de folhas de Montrichardia linifera (Arruda) Schott, Araceae(Universidade Federal do Pará, 2009-12) COSTA, Eliene dos Santos da Silva; DOLABELA, Maria Fâni; PÓVOA, Marinete Marins; OLIVEIRA, Davi de Jesus; MÜLLER, Adolfo HenriqueItem Acesso aberto (Open Access) Impacts of urban life on water quality and fish larvae communities in two creeks of the Brazilian Amazon(2016-03) SOUZA, Claíde Lorena Reis de; COSTA, Vanessa Bandeira da; PEREIRA, Simone de Fátima Pinheiro; SILVA, Debora Cristina Melo da; SARPEDONTI, ValérieThis study investigated the impact of anthropogenic activities in Belém City, Brazilian Amazon, by comparing water quality and fish larvae communities in two creeks that flow into the Guamá River. One creek crossed a poor and crowded suburb of Belém while the other was located in an island section that was declared an Environmental Protected Area in 1997. Two sampling points were set in each creek and monitored over eight hours once every three months over a one-year period. Strong variations of water quality were registered all year long and at all tides in Belém's mainland creek, along with, among other things, a very high number of thermotolerant coliforms. Few larvae were found. The water was considered unsuitable for human use and activities as well as for aquatic life. The island creek presented early signs of bacterial and nutrient contaminations during the rainy season, probably partly related to non-point source pollution. In both creeks, larvae communities were almost exclusively composed of clupeiforms. All larval development stages were encountered. Higher densities and proportion of newly hatched larvae were registered during the dry season and associated with the presence of nitrate. The results of the study show that adequate sewage and drainage systems must be developed in the city and suggest that it would be useful to conduct an integrated ambient monitoring study in Combú Creek.Item Acesso aberto (Open Access) Dados espectroscópicos de diterpenos labdânicos: uma análise teórica via RMN e DFT(2015-06) SOUZA, Fabrine Silva de; SILVA, Silvana de Oliveira; FARIA, Lênio José Guerreiro de; ALVES, Claudio Nahum; MÜLLER, Adolfo Henrique; GUILHON, Giselle Maria Skelding Pinheiro; BRASIL, Davi do Socorro BarrosLabdane diterpenes exhibit important bioactivities such as cardiovascular effects in rats as well as effects in the treatment of autoimmune diseases and Alzheimer syndrome. Recently, the labdane diterpenes ent-13-epi-manoil oxide, ribenone and ribenol were isolated from Croton palanostigma. The computational method DFT/B3LYP/cc-pVDZ was used to optimize the structures of these diterpenes and to calculate infrared data. Chemical shifts (δH and δC) of the minimum energy structures (local minimum) were calculated and compared with the experimental data. Comparison of the NMR data by simple linear regression (SLR) showed satisfactory statistical results with a correlation coefficient (R2) and predictive ability (Q2) of over 98%. The predicted NMR data were used to confirm the δH values that have not been published.Item Acesso aberto (Open Access) Influência do método de preparação de eletrocatalisadores PtRu/C sobre a atividade catalítica frente à reação de oxidação de etanol em meio ácido(2013) GOMES, Walber dos Santos; SILVA, Uriel Lean Valente; SOUZA, José Pio Iúdice deIn this work the influence of variations in the borohydrate reduction method on the properties of PtRu/C electrocatalysts was investigated. The electrocatalysts were prepared using 1:1 ; 2:1; 5:1; 50:1 and 250:1 molar ratios of NaBH4 to metals. The reduction was also performed by dripping or by fast addition of the solution. The results showed that PtRu nanoparticles obtained by fast addition had the smallest crystallite sizes. It was also noted that the catalytic activity increased as the borohydrate:metal molar ratio increased. The PtRu/C electrocatalyst (50:1) obtained by fast addition presented the best catalytic activity for ethanol electro-oxidation.Item Acesso aberto (Open Access) Desenvolvimento de conjunto membrana-eletrodos para célula a combustível de metanol direto passiva(2010) FERREIRA, Eli Carlos Lisboa; QUADROS, Fabrício Monteiro; SOUZA, José Pio Iúdice de; TANAKA, Auro AtsushiDirect methanol fuel cells (DMFCs) without external pumps or other ancillary devices for fuel and oxidant supply are known as passive DMFCs and are potential candidates to replace lithium-ion batteries in powering portable electronic devices. This paper presents the results obtained from a membrane electrode assembly (MEA) specifically designed for passive DMFCs. Appropriated electrocatalysts were prepared and the effect of their loadings was investigated. Two types of gas diffusion layers (GDL) were also tested. The influence of the methanol concentration was analyzed in each case. The best MEA performance presented a maximum power density of 11.94 mW cm-2.Item Acesso aberto (Open Access) Estudo da qualidade da gasolina tipo A e sua composição química empregando análise de componentes principais(2014) CARVALHO, Fabio Israel Martins; DANTAS FILHO, Heronides AdoniasThe type A gasoline samples were analyzed by gas chromatography with flame ionization detector (GC-FID) which allowed quantifying and classifying of the various compounds into different classes of hydrocarbons. Several physicochemical parameters were evaluated according to the official methods in order to compare the results obtained against the limits established by the Agência Nacional de Petróleo, Gás Natural e Biocombustíveis (ANP, 2011). Additionally, principal component analysis (PCA) was applied to discriminate the samples studied, which revealed the separation of four groups according to their chemical composition determined in samples collected from the eight fuel distributors in the State of Pará.Item Acesso aberto (Open Access) Aleloquímico produzido pela gramínea forrageira Brachiaria humidicola(2005-03) SOUZA FILHO, Antonio Pedro da Silva; PEREIRA, Angela Albertina Gaspar; BAYMA, Joaquim de CarvalhoThe traditional methods of weed control in cultivated pasture do not meet society's present and future needs of protecting natural resources and life quality. An alternative to this problem could be the use of secondary metabolites produced by plants. These products present few risks to the environment and meet society interests. Therefore, this research was carried out to isolate, identify and characterize the allelopathic activity of chemical compounds produced by the forage grass Brachiaria humidicola. The allelopathic effects of the extracts, fractions and compound were tested on seed germination and root elongation of the weeds Mimosa pudica, Senna obtusifolia and Senna occidentalis. Germination bioassays were developed under 25 ºC and a photoperiod of 12 hours. For root elongation, the bioassay conditions were 25 ºC and photoperiod of 24 hours. Hydromethanolic extract was used as a source for isolating and identifying p-coumaric acid. The allelopathic effects were positively related to p-coumaric acid concentration, weed species and the evaluated parameter. Comparatively, S. occidentalis and M. pudica showed the greatest sensitivity to the allelopathic effects. For S. obtusifolia no allelopathic effects promoted by p-coumaric acid on seed germination or on root elongation could be detected under the concentration of 1.0 and 8.0 mg L-1. Root elongation was more sensitive to p-coumaric acid allelophatic effects than seed germination.Item Acesso aberto (Open Access) Atividade alelopática de substâncias químicas isoladas da Acacia mangium e suas variações em função do PH(2010) LUZ, Sylmara de Melo; SOUZA FILHO, Antonio Pedro da Silva; GUILHON, Giselle Maria Skelding Pinheiro; VILHENA, Karyme do Socorro de SouzaThe aim of this study was to isolate, identify and characterize the allelopathic activity of the substances produced by Acacia mangium and to determine the variations of this activity according to the pH variation of the solution. The allelopathic activity was evaluated in germination bioassays (at 25 oC and under 12-12 h light-dark cycle) and radicle and hypocotyl development (at 25 oC and under 24-24 h light-dark cycle) of the weed species malicia (Mimosa pudica) and mata-pasto (Senna obtusifolia). The influence of the pH (3.0 and 9.0) of the solution in the allelopathic activity of the substances on seed germination of the same species was evaluated. The triterpenoids Lupenone (3 oxolup-20(29)-ene) and Lupeol (3β-hydroxylup-20(29)-ene), obtained from fallen leaves of the donor plant, separately and in pair, showed low allelopathic effects on seed germination and hypocotyl growth, especially on the former, with effects showing values lower than 2%. The effects on radicle growth were higher than the other two, reaching values above 40%, especially inhibition promoted by the substance Lupenone. Separately, each substance showed higher effects than those observed when tested in pair, indicating the existence of antagonism. The pH of the solution influenced the allelopathic activity of the substances; for Lupenone, the effects were more intense at acidic pH, while for Lupeol, best results were observed under alkaline conditions, showing that this is an important factor to be considered in field works.Item Acesso aberto (Open Access) Biologically active polyketides produced by Penicillium janthinellum isolated as an endophytic fungus from fruits of Melia azedarach(2005-04) MARINHO, Andrey Moacir do Rosário; RODRIGUES FILHO, Edson; MOITINHO, Maria da Luz Ribeiro; SANTOS, Lourivaldo da SilvaPenicillium janthinellum, isolated as an endophytic fungus from fruits of Melia azedarach, was cultivated over 20 days on ground and autoclaved white corn, where the known polyketides citrinin, emodin, 1,6,8-trihydroxy-3-hydroxymethylanthraquinone, and a new modified anthraquinone, named janthinone, were produced and isolated by classical chromatographic procedures and identified by MS and 1D and 2D NMR spectroscopic data. The antibacterial properties of these polyketides were investigated. Citrinin inhibited 100% of Leishmania growth after 48h at a concentration of 40 μg mL-1.Item Acesso aberto (Open Access) Identification and antioxidant activity of several flavonoids of Inga edulis leaves(2007) SOUZA, Jesus Nazareno Silva de; SILVA, Evaldo Martins da; SILVA, Milton Nascimento da; ARRUDA, Mara Silvia Pinheiro; LARONDELLE, Yvan; ROGEZ, Hervé Louis GhislainA methanol-water extract of Inga edulis leaves was fractionated to identify the polyphenolic compounds. The identified compounds were gallic acid, catechin, epicatechin, myricetin-3-rhamnopyranoside, quercetin-3-glucopyranoside and quercetin-3-rhamnopyranoside. The antioxidant activity of the extract and of pure polyphenols was measured by the ORAC assay and compared with the Total Phenolic (TP) content. The dry crude extract presented very high values for ORAC (11.16 mmol TE per g) and TP (496.5 mg GAE per g). The identified compounds were responsible for 9.53 % and 12.10 % of the ORAC value and TP content of the Inga edulis leaf extract, respectively.Item Acesso aberto (Open Access) Determination and fractionation of barium in Brazil nuts(2009) GONÇALVES, Alexandra Mary; DANTAS, Kelly das Graças Fernandes; RAMOS, Luiz Antônio; CAVALHEIRO, Éder Tadeu Gomes; NÓBREGA, Joaquim de AraújoSeveral sample preparation strategies were employed for determination and fractionation of barium in Brazil nuts using measurements by graphite furnace atomic absorption spectrometry (GF AAS) and inductively coupled plasma optical emission spectrometry with axial view (ICP OES). This food is widely consumed because of its nutritional value and good taste. The chemical analysis of Brazil nuts is not trivial due to their complex matrix. The fractionation of barium in Brazil nuts was studied owing to the toxicity of this element and the strong correlation between chemical form and absorption. Total concentrations of barium varied from 860 to 2084 mg kg-1. Sequential extractions were performed based on solubility in different media and also according to lipids, proteins and low molecular weight fractions (LMW). The greatest contents of barium were determined in the LMW and in the water insoluble fractions with concentrations in the range 778 to 1606 and 551 to 1520 mg kg-1, respectively. Based on these results it can be inferred that Ba is not absorbed when Brazil nuts are ingested. Considering both the contents of barium and sulfur in different fractions and stoichiometric calculations it was also possible to assume that barium occurs mainly in the BaSO4 form. The presence of this chemical form was also confirmed by thermogravimetric measurements.Item Acesso aberto (Open Access) Application of carbon composite adsorbents prepared from coffee waste and clay for the removal of reactive dyes from aqueous solutions(2015-05) SANTOS, Davis Castro dos; ADEBAYO, Matthew Ayorinde; LIMA, Éder Cláudio; PEREIRA, Simone de Fátima Pinheiro; CATALUÑA VESES, Renato; SAUCIER, Caroline; THUE, Pascal Silas; MACHADO, Fernando MachadoA novel carbon composite was prepared from a mixture of coffee waste and clay with inorganic:organic ratio of 1.3 (CC-1.3). The mixture was pyrolysed at 700 °C. Considering the application of this adsorbent for removal of anionic dyes, the CC-1.3 was treated with a 6 mol L-1 HCl for 24 h to obtain ACC-1.3. Fourier transform infrared (FTIR), N2 adsorption/desorption curves, scanning electron microscope (SEM) and powder X-ray diffractometry (XRD) were used for characterisation of CC-1.3 and ACC-1.3 carbon adsorbents. The adsorbents were effectively utilised for removal of reactive blue 19 (RB-19) and reactive violet 5 (RV-5) textile dyes from aqueous solutions. The maximum amounts of RB-19 dye adsorbed at 25 °C are 63.59 (CC-1.3) and 110.6 mg g-1 (ACC-1.3), and 54.34 (CC-1.3) and 94.32 mg g-1 (ACC-1.3) for RV-5 dye. Four simulated dye-house effluents were used to test the application of the adsorbents for treatment of effluents.Item Acesso aberto (Open Access) Square-wave voltammetric determination of rutin in pharmaceutical formulations using a carbon composite electrode modified with copper (II) phosphate immobilized in polyester resin(2012-12) FREITAS, Kellen Heloizy Garcia; FATIBELLO FILHO, Orlando; MATTOS, Ivanildo Luiz deA carbon composite electrode modified with copper (II) phosphate immobilized in a polyester resin (Cu3(PO4)2-Poly) for the determination of rutin in pharmaceutical samples by square-wave voltammetry is described herein. The modified electrode allows the determination of rutin at a potential (0.20 V vs. Ag/AgCl (3.0 mol L--1 KCl)) lower than that observed at an unmodified electrode. The peak current was found to be linear to the rutin concentration in the range from 9.9 × 10-8 to 2.5 × 10-6 mol L-1, with a detection limit of 1.2×10-8 mol L-1. The response of the electrode was stable, with no variation in baseline levels within several hours of continuous operation. The surface morphology of the modified electrode was characterized by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) system. The results obtained are precise and accurate. In addition, these results are in agreement with those obtained by the chromatographic method at a 95% confidence level.Item Acesso aberto (Open Access) Distribuição de mercúrio total em sedimentos da plataforma continental Amazônica: Brasil(Instituto Nacional de Pesquisas da Amazônia, 2012-06) SIQUEIRA, Gilmar Wanzeller; APRILE, Fábio MarquesThis study was developed at the Amazon Continental Shelf aims to determine the levels of total mercury in the sediment bottom, and them to contribute as environmental matrix for the general plan of coastal monitoring in the North Region of the Brazil. Twenty sampling sites between May and June from 1999 to 2002, 2005 and 2007 were analyzed. The results indicate there is not evidence of anthropic activities associated to the contamination by mercury in the region. The levels of total mercury founded range between 0.047 and 0.166 mg kg-1 with average of 0.085±0,026 mg kg-1. The results are inside of the background interval determined to not contaminated or not polluted Amazon Rivers, which the interval ranges from 0.05 to 0.28 mg kg-1. The mercury concentrations in the sediment bottom, especially in the mud sediment, had shown a narrow dependence with both the clay levels (fine material) and organic matter, corroborating important geochemical mechanisms in Hg dynamics. The largest adsorption of the mercury can be associated to the increase of the oxides and hydroxides compounds of iron, aluminum, manganese and others primary and secondary minerals from the rocks of the Amazon drainage basin.Item Acesso aberto (Open Access) Diagnóstico da qualidade da água do rio Parauapebas (Pará - Brasil)(Instituto Nacional de Pesquisas da Amazônia, 2012-09) SIQUEIRA, Gilmar Wanzeller; APRILE, Fábio Marques; MIGUÉIS, Antonio Miguel BorreganaThe objective of this research was to develop a diagnostic of the water quality of the Parauapebas River (Pará, Brazil), in the dry periods of 2004, 2007 and 2009. In 20 sampling sites in Parauapebas River, around of the Parauapebas City, physical (transparency, water temperature and total solid residues), chemical (dissolved oxygen, pH, turbidity, alkalinity, hardness, acidity, chloride, Biochemical Oxygen Demand, Chemical Oxygen Demand, total phosphorus, total iron and total nitrogen), and biological parameters (thermotolerant coliforms) were measured. The results were used for the determination of Water Quality Index (WQI). As support to the interpretation of these parameters, a Principal Components Analysis (PCA), multiple regression and linear regression analyses and, a general survey of physical, biotical and social-economic of the region were performed. WQI for the Parauapebas River, in the monitored area, was 40.01, which classifies it in the category "Regular". The PCA and multiple regression analysis identified four parameters that have been employed in the WQI determination and that influenced significantly the variation of the Index: dissolved oxygen, BOD, total phosphorus and thermotolerant coliforms, which explained 75% of the variation of the results. The results indicate that the urban expansion, in especial in the directions N-NW and S-SW, has reached the areas surrounding the Riparian Forest, and affected partially the surface water quality of the Parauapebas River.Item Acesso aberto (Open Access) Determinação espectrofotométrica do arsênio em solo da cidade de Santana-AP usando o método do dietilditiocarbamato de prata (SDDC) modificado(Instituto Nacional de Pesquisas da Amazônia, 2009) PEREIRA, Simone de Fátima Pinheiro; OLIVEIRA, Geiso Rafael Fonseca; OLIVEIRA, Johny da Silva; SILVA, Juliane da Silva e; SOUSA JUNIOR, Pedro Moreira deSeveral tons of manganese residues containing arsenic, generated by a mining company, were used as streets landfill in Santana-Ap city. The possibility of exposure of people living in these villages has led to the study of quantification of total arsenic in the soil. After digestion, the levels of arsenic were quantified by molecular absorption spectrophotometry using a hydrides generation automatic system (HG-MAS), dicyclohexilamine/CHCl3 as silver diethyldithiocarbamate (SDDC) solvent and KBH4 as reducer. The method presented good results with sensitivity (ε) of 1.10 104 l.mol-1.cm-1, stability of 2.96 % and other advantages in relation to the official method. The method was applied to the soil standard samples with recoveries of the 98.82 % (n=10). The soil analysis showed that 94.74 % samples showed arsenic concentrations above the value published by CETESB for residential land (50 mg.kg-1) with the average value of 682.96 mg.kg-1, ranging of 48.08 mg.kg-1, at 1,713.00 mg.kg-1 shows that the soil arsenic contamination.Item Acesso aberto (Open Access) Spectrophotometric determination of arsenic in soil samples using 2-(5-bromo-2-pyridylazo)-5-di-ethylaminophenol (Br-PADAP)(2008) PEREIRA, Simone de Fátima Pinheiro; FERREIRA, Sérgio Luis Costa; OLIVEIRA, Geiso Rafael Fonseca; PALHETA, Dulcidéia da Conceição; BARROS, Bruno de Cássio Veloso deIn this paper, a new, simple and sensitive method for arsenic determination in soil is proposed. This is based on the reduction of silver (I) and iron (III) ions by arsine followed by a complexation reaction of iron (II) with the spectrophotometric reagent Br-PADAP 2-(5-bromo-2-pyridylazo)-5-di-ethylaminophenol. Arsenic determination with a Sandell's sensitivity of 3.1 10-4 cm-2, linear range from 0.1 µg ml-1 to 2.0 µg ml-1 (r560 = 0.9995), molar absorptivity of 2.45 105 l mol-1 cm-1 and a concentration detection limit of 1.4 ng ml-1 (3s) were obtained using a 10 ml sample volume. Selectivity was increased with the use of EDTA as a masking agent. The proposed method was applied for arsenic determination in the presence of several ions amounts in digested soil samples. The results revealed that antimony (III), mercury (II), germanium (IV), platinum (IV) interferes at all analyzed proportions. The interferences can be easily removed by the use of EDTA. Precision and accuracy obtained were satisfactory with a R.S.D. < 5 %. Recovery of arsenic in soil samples varied from 95.55 to 102.70 % with a mean of 99.63 %. These results demonstrated that the proposed method is applicable for arsenic analysis in different soil samples.