SIBI! EM BREVE O RIUFPA ESTARÁ LIBERADO! AGUARDEM!

Artigos Científicos - ICEN

URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/2557

Navegar

Agora exibindo 1 - 20 de 30

Acesso aberto (Open Access)
Análise de aproximações das concepções presentes em questões associadas ao ensino de química aplicadas no novo ENEM com as concepções do enfoque CTS
(Universidade Federal do Pará, 2019-06) SOUZA, Jorge Raimundo da Trindade; BRITO, Licurgo Peixoto de
The National High School Examination (Enem) comprehends the evaluation of skills and competences fundamental to the exercise of citizenship, one of the objectives of the Science, Technology and Society (STS) approach. This qualitative research, which also adopts quantitative standards, has the objective of analyzing STS concepts in the issues associated to the chemistry teaching of this exam, in the period between 2009 to 2015 (new Enem), and the factors that influence these relations. For this, it was necessary to analyze the content and the structure of the questions associated to the teaching of Chemistry, examining if and how occurred the approximation of these questions with the principles of the STS educational perspective, and what conditions determine the mediation of this relation of proximity. As an instrument for analyzing the questions, the Discursive Textual Analysis (ATD) was used. Among the 156 analyzed questions, which are pertinent to the teaching of Chemistry, 46.1% did not present an approximation with the principles of the STS approach; 32.1% showed an apparent relationship with these assumptions and 21.8% were associated with the principles of the STS approach. The results showed that the questions of the new Enem presented proximity, at different levels, to the theoretical principles of the STS approach.
Acesso aberto (Open Access)
Theoretical study of plasmonically induced transparency effect in arrays of graphene-based double disk resonators
(Sociedade Brasileira de Micro-ondas e Optoeletrônica, 2019-03) PORTELA, Gianni Masaki Tanaka; DMITRIEV, Victor Alexandrovich; OLIVEIRA, Cristiano Braga de; CASTRO, Wagner Ormanes Palheta
In this paper, we consider coupled disk-shaped resonators separated by a thin dielectric substrate that can be used as frequency-tunable filters or as electromagnetic switches in the terahertz frequency band. The two disks are electromagnetically coupled and resonate with dipole plasmonic modes. By using a Temporal Coupled-Mode Theory based approach, we show how to analytically calculate the frequency response of such structures.The analytical results are in good agreement with those obtained from computational simulations based on the finite element method.
Acesso aberto (Open Access)
Sedimentary transport influences on diagenetic processes at the Amazon continental shelf, Brazil
(SCIENCEDOMAIN International, 2019) APRILE, Fábio Marques; SIQUEIRA, Gilmar Wanzeller; DARWICH, Assad José; IRION, Georg Friedrich
This research aimed to correlate the sedimentary transport with the diagenetic processes in the coastal zone and Amazon Continental Shelf (ACS). Physical and physical-chemical parameters, trace element contents (Cr, Pb, Ni, Zn and Hg), and O2, CO2 and iron flux were determined in sediment and pore water. Sedimentary incubation (96 hours) and algorithms were applied to determine the variation of the activity coefficient (ΔI) and ionic strength (Fi) of the predominant chemical species, and to estimate the net production and mineralization of the organic matter (ΔCO2T) in the system. There are not many studies applying incubation tests to identify the diagenetic processes, especially in fluvial-marines sediments. The results showed a strong zonation associated to the transport and deposition processes, influenced mainly by the grain-size and texture of sediment and fluvial streams. The distribution of trace elements followed the trend of the sedimentary pattern, with higher levels of metals in the deposits of clay minerals and organic matter. A factor of weight (Fw), calculated to establish the degree of importance of each parameter under the distribution and mobility of trace elements, suggests that the mobility of Cr, Ni and Zn is controlled by depth, clay and organic compounds contents, and concentration of dissolved oxygen.The vertical flow of O2 and CO2 and the Fe2+/Fe3+ ratio in the pore water suggest a predominance of organic matter oxidation in the sedimentary layer between 0.0 and 0.2 m, with partially anaerobic mineralization of the sediments below 0.4 m. Increases in trace element concentrations were observed in iron reduction zones, indicating processes of desorption of oxides and hydroxides of Fe and mineralization of organic matter. The extrapolation of the results of the incubation test to the studied system allowed to establish three hypotheses related to the diagenetic processes: 1) the flow of marine currents may be allowing the aerobic oxidation in the sandy sediments, with the nitrification route more accentuated than the ammonification route; 2) in the region of the coastal zone and inner continental shelf the routes of oxidation and reduction may be alternating according to the physical-chemical factors and seasonality; 3) in the coastal zone and inner shelf the net mineralization rate exceeded the net production rate of the organic matter (ΔCO2T >0).
Acesso aberto (Open Access)
Hydrogeological Characteristic and the Vulnerability Degree of the Aquifers from Municipality of Abaetetuba, Pará - Brazil
(Universidade Federal do Pará, 2019-03) LEITE, Andreza Cristina Morais; SIQUEIRA, Gilmar Wanzeller; DARWICH, Assad José; APRILE, Fábio Marques
This study evaluated the quality of groundwater in the municipality of Abaetetuba (PA, Brazil 1°43'46'' S e 48°52'27'' W) based on the hydrogeological characterization and degree of vulnerability of the aquifer system. The municipality of Abaetetuba is practically all supplied by groundwater both by deep tubular wells and shallow pit wells (Amazonian wells), which present potential risk of contamination. Water and soils samples from 20 wells sampled between 2012 and 2016 were used. Physicochemical and microbiological analyzes served as a data base for mapping (GIS). Three hydrogeological domains were identified within the study area: Barreiras Group (predominant), Post-Barrier Sediments and Recent Sediments. Almost all of the samples presented microbiological levels above the MPV defined by the Brazilian legislation for water intended for human consumption. The DRASTIC and GOD vulnerability indexes presented values between 75 and 119 and 0.15 and 0.32 respectively, suggesting areas of 'low' to 'moderately-high' vulnerability. Local sources of pollution by coliforms have been identified due to lack of basic sanitation. Evidence of diffuse sources derived from vehicle washing and lubrication also have been identified. Although the Barreiras Group had deep semi-confined aquifers, a 'state of alert' was suggested for the areas that indicated the presence of fecal coliforms and with a high population density. Isovalues and vulnerability maps suggest areas that require further monitoring. A positive correlation between the DRASTIC Index and TDS in well water was established. The intense exploitation of groundwater especially in areas of great population density may be causing contamination of aquifers.
Acesso aberto (Open Access)
Densidade crítica no modelo de percolação em rede de Bethe não-homogênea
(Sociedade Brasileira de Matemática Aplicada e Computacional, 2015-08) TAVARES, Héliton Ribeiro; SOUZA, Raimundo Nonato Carneiro de; TAVARES, Maria Regina Madruga; FARIAS, Valcir Joao da Cunha
In this work we deal with an inhomogeneous Bethe lattice percolation model where the probability of an edge in level n is open changes according as n. This model can be appropriate to the case where the media changes its density in a systematic way, such as the proliferation of insects that depends on the temperature and humidity, which fluctuates between day and night. We consider the case where the density p(·) follows a function of the distance l(.) from the origin, given by a sinusoid function p(·) = p + (1 - p)|sin(l(.))|. For this model we present results of Monte-Carlo simulation showing the behavior of the probability of percolation with a second-order phase transition, but we present too a formal proof that the density is non trivial, with the mathematical expression to compute the percolation threshold.
Acesso aberto (Open Access)
Characterization of the Fruit Pulp of Camu-Camu (Myrciaria dubia) of Seven Different Genotypes and Their Rankings Using Statistical Methods PCA and HCA
(Universidade Federal do Pará, 2016-10) FREITAS, Camila Auad Beltrao de ; SILVA, Antonio dos Santos; ALVES, Claudio Nahum; NASCIMENTO, Walnice Maria Oliveira do; LOPES, Alessandra Santos; LIMA, Marcelo de Oliveira; MÜLLER, Regina Celi Sarkis
Due to the economic potential of camu-camu, considering its high concentration of vitamin C, the aim of this work was to evaluate the quality and genetic variability seven accessions of camu-camu conserved in genebank (BAG) of Embrapa Amazônia Oriental, in the state of Pará, Amazon region, Brazil. The fruits of camucamuzeiro were analyzed for physicochemical characterization (standard methodologies) and mineral composition. The data were subjected to multivariate statistical analysis, using the techniques of cluster analysis and principal component analysis. The formation of different groups for each genotype, which shows the genetic variability and the dissimilarity of the genotypes in the species data, may be used to guide the selection of promising genotypes to enrich the programs of genetic improvement of the camucamuzeiro. Ascorbic acid showed levels above 1000 mg 100 g-1, however, genotypes 4, 1 and 2 show the highest potential and the most promising nutritional capacity, but genotype 4 showed good characteristics for the moisture, acidity, carbohydrates, Cu and Zn and differs totally from others about the total soluble solids (TSS) and flavon-3-ol, features that make it the most promising genotype. It was possible to separate the seven different genotypes using multivariate analysis (hierarchical cluster analysis-HCA and principal component analysis-PCA).
Acesso aberto (Open Access)
A New Prenylisoflavone from the Antifungal Extract of Leaves of Vatairea guianensis Aubl.
(Universidade Federal do Pará, 2017-06) SOUZA, Ronilson Freitas de; SILVA, Geilson Alcantara da; ARRUDA, Alberto Cardoso; SILVA, Milton Nascimento da; SANTOS, Alberdan Silva; GRISÓLIA, Daniella Paternostro de Araújo; SILVA, Moisés Batista da; ARRUDA, Mara Silvia Pinheiro
A new compound, 5,7,3'-trihydroxy-4'-methoxy-8-prenylisoflavone, was isolated from the leaves of Vatairea guianensis Aubl. (Fabaceae), together with two known isoflavones lupiwighteone and 5,7,4'-trihydroxy-3'-methoxy-8-prenylisoflavone. All isolated compounds were characterized based on infrared (IR), UV, 1H and 13C nuclear magnetic resonance (NMR), including 2D NMR analyses and high resolution mass spectrometry. The ethanolic extract from V. guianensis leaves displayed activity against Candida dubliniensis, C. albicans and C. krusei. However, the EtOAc fraction from that extract exhibited more significant activity than the ethanolic extract, showing antifungal activity for all fungi species investigated. The major compound 5,7,3'-trihydroxy-4'-methoxy-8-prenylisoflavone isolated from that EtOAc fraction was also active against C. parapsilosis and C. dubliniensis.
Acesso aberto (Open Access)
Influência da exploração florestal de impacto reduzido sobre as fases de desenvolvimento de uma floresta de terra firme, pará, brasil
(Universidade Federal do Pará, 2013-12) FRANCEZ, Luciana Maria de Barros; CARVALHO, João Olegário Pereira de; BATISTA, Fábio de Jesus; JARDIM, Fernando Cristóvam da Silva; RAMOS, Edson Marcos Leal Soares
The influence of reduced impact logging were evaluated on the growth phases of a terra firme forest in the Paragominas region, state of Pará, that was logged considering two intensities of timber harvesting. Data were collected in 36 permanent sample plots (0.25ha) randomly distributed among treatments (T1 – Logged forest, harvesting the stem of commercial trees; T2 – Logged forest, harvesting the stem and coarse woody debris) and control (T0 unlogged forest). Three growth phases of the forest were considered: mature (DBH > 40cm); building forest (10cm < DBH < 40cm); and gaps (occurrence of a canopy gap and a few or no tree with DBH > 10cm). The homogeneity of variances of sub-plots between treatments, growth phases and years was tested by the Bonferroni test, according to the statistics of Bartlett and Levene. An analysis of variance was applied on the number of sub-plots by phases, years and treatments at a 0.005 significance level. The Tukey test was applied for analyzing the interaction between the phases and years. Before logging the percentage of growth phases were: 57.0% building forest, 38.9% mature forest and 4.1% canopy gaps. Logging reduced the areas of mature forest and building forest, increasing the number of canopy gaps, but this increase had no statistical difference. One year after logging the area of mature forest (38.4%) and building forest (53.1%) increased while the areas of gaps (8.4%) decreased. Three years after logging the percentage of mature forest (37.1%), building forest (57.9%) and gaps (5.0%) were similar to those found before logging. The forest growth phases were not influenced by logging, over the study period. The study forest showed that it is able to grow, closing the canopy gaps, even in a short period of time.
Acesso aberto (Open Access)
Phytosterols isolated from endophytic fungus Colletotrichum gloeosporioides (Melanconiaceae)
(Instituto Nacional de Pesquisas da Amazônia, 2016-03) CARVALHO, Josiwander Miranda; PAIXÃO, Luanna Karyna Olimpio da; DOLABELA, Maria Fâni; MARINHO, Patrícia Santana Barbosa; MARINHO, Andrey Moacir do Rosário
Endophytic fungi are fungi that colonize internal tissues of plants. There are few studies of compounds isolated from endophytic fungi of Amazon plants. Thus, the aim this study was the isolation and structural identification of sitosterol (1), stigmasterol (2), sitostenone (3), squalene (4), ergosterol (5) and ergosterol peroxide (6) from fungus Colletotrichum gloeosporioides isolated as endophytic from Virola michelli, a typical Amazon plant, used in folk medicine against skin infection. Compounds were isolated by chromatography column on silica and identified by 1 H and 13C NMR and MS. The presence of phytosterols in fungi is rare and this is the first report of the isolation of the phytosterols sitosterol, stigmasterol and sitostenone from the genus Colletotrichum.
Acesso aberto (Open Access)
Ecofisiologia de plantas jovens de mogno-africano submetidas a deficit hídrico e reidratação
(2013-01) ALBUQUERQUE, Marcos Paulo Ferreira de; MORAES, Fabrícia Kelly Cabral; SANTOS, Rodolfo Inacio Nunes; CASTRO, Gledson Luiz Salgado de; RAMOS, Edson Marcos Leal Soares; PINHEIRO, Hugo Alves
The objective of this work was to evaluate the capacity of young plants of African mahogany (Khaya ivorensis) to recover their water status and gas exchange after water deficit. Plants with approximately 315 days, irrigated (control) and non-irrigated, were evaluated after water was withheld for 14 days, and after one, three, and seven days of irrigation resumption (rehydration). On day 14, the predawn leaf water potential (Ψam) of stressed plants was reduced to -2.66 MPa. With water deficit, significant decreases were observed in predawn relative water content (32% reduction), in net assimilation rate of CO2 (90%), in stomatal conductance (95%), in transpiration (93%), and in intercellular to ambient ratio of CO2 concentration (37%). During rehydration, the water status of stressed plants was recovered after three days. Gas exchange was also recovered, but in a slower rate than water status. Under water deficit, proline concentration increased and total soluble carbohydrate concentration decreased. Young African mahogany plants are tolerant to moderate water deficit.
Acesso aberto (Open Access)
Ethanolysis optimisation of Jupati (Raphia taedigera Mart.) oil to biodiesel using response surface methodology
(2015-07) CONCEIÇÃO, Leyvison Rafael Vieira da; COSTA, Carlos Emmerson Ferreira da; ROCHA FILHO, Geraldo Narciso da; PEREIRA FILHO, Edenir Rodrigues; ZAMIAN, José Roberto
In this work, the transesterification of jupati (Raphia taedigera Mart.) oil using ethanol and acid catalyst was examined. The production of biodiesel was performed using a central composite design (CCD). A range of values for catalyst concentration (1 to 4.21%), temperature (70-80 °C), and the molar ratio of alcohol to oil (6:1-13.83:1) were tested, and ester content, viscosity, and yield were the response variables. The synthesis process was optimised using response surface methodology (RSM), resulting in the following optimal conditions for the production of jupati ethyl esters: a catalyst concentration of 3.85% at 80 °C and an alcohol-to-oil molar ratio of 10:1.
Acesso aberto (Open Access)
Characterization and distribution of pyrogenic carbon in a fraction of archaeological black earth from Caxiuanã
(2015-08) MORAES, Milena Carvalho de; LEMOS, Vanda Porpino; MORAES, Dorsan dos Santos; MORAES, Cláudio Nery Lamarão
This study aims to determine the atomic ratio of O/C in an archaeological black earth (ABE) profile of the Ilha de Terra site, a region of Caxiuanã in the Pará State, Brazil, to determine the types of pyrogenic carbon (PyC) particles and to infer the source of biomass and burning temperature necessary to produce the PyC. The O/C ratios were monitored using scanning electron microscopy combined with energy dispersive spectroscopy (SEM/EDS). The results indicated atomic ratios for clay, silt and fine sand fractions that were between those registered for the PyC particles types: condensed combustion (CC) (0.09, 0.1, 0.13), charcoal (0.32, 0.31, 0.34) and char (0.43, 0.45, 0.52). CC is the predominant type of particle found because of the high firing temperature (> 350 °C), which is consistent with the probable biomass sources of wood, cellulose and lignin.
Acesso aberto (Open Access)
Novel technique for locating an intruder in 3D environments by using a cooperative system of multistatic radars
(2011-12) ARAÚJO, Josivaldo de Souza; OLIVEIRA, Rodrigo Melo e Silva de; SOUZA SOBRINHO, Carlos Leônidas da Silva
The aim of this work is to present a new methodology, based on vector and geometrical techniques, for determining the position of an intruder in a residence (3D problem). Initially, modifications in the electromagnetic responses of the environment, caused by movements of the trespasser, are detected. It is worth mentioning that slight movements are detected by high frequency components of the used pulse. The differences between the signals (before and after any movement) are used to define a sphere and ellipsoids, which are used for estimating the position of the invader. In this work, multiple radars are used in a cooperative manner. The multiple estimates obtained are used to determine a mean position and its standard deviation, introducing the concept of sphere of estimates. The electromagnetic simulations were performed by using the FDTD method. Results were obtained for single and double floor residences.
Acesso aberto (Open Access)
O papel da incerteza no planejamento de sistemas de educação a distância
(2008-08) ELIASQUEVICI, Marianne Kogut; PRADO JÚNIOR, Arnaldo Corrêa
The task of planning a system of distance education (SDE) is a complex process due to the number of components involved, the different views and approaches as to their efficacy, the contending values, the interests at play, and the urgent decisions often needed. This work starts from the experience available in books and articles by the authors, and draws from part of the doctorate thesis of one of them, with the purpose of describing the importance of uncertainty analysis in programs of distance education, thereby contributing to reduce the probability of occurrence of undesirable and/or unexpected events in various situations characterized by complex environments. It describes the trajectory of uncertainty in the perspective of science, and presents a theoretical framework to give support to the problem of planning SDEs. It also mentions the ways in which uncertainties can enter decision processes and the setting up of SDEs, taking as its source a study carried out in the State of Pará. Strategies were devised with a view to improve the articulation of initiatives in the various areas involved, in order to maximize the participation of the different actors and to reinforce the role of distance education as a public policy for social inclusion. In its final considerations, the article emphasizes the applicability of this investigation to other situations. The work aims at contributing to define strategic guidelines for the implementation of SDEs.
Acesso aberto (Open Access)
Estudo do crescimento de nanofitas de céria dopada com gadolínio por sistema de aquecimento por micro-ondas
(2013-09) GONÇALVES, Rosana de Fátima; CASTRO, D. A.; SANTOS, Maria Rita de Cássia; FIGUEIREDO, Alberthmeiry Teixeira de; BARRADO, Cristiano Morita; LEITE, Edson Roberto; GODINHO JÚNIOR, Mario
Cerium oxide (ceria) has attracted attention because of its important applications such as solid oxide fuel cells, catalysts for automobile exhaust gas, catalysts to obtain hydrogen, UV blockers, biomaterials, etc.. Control methods for synthesis of ceria are of great importance to explain or predict these properties. Thus, the objective of this work was to study the growth of cerium oxide nanobelts in a microwave-assisted hydrothermal system, where in 8 min 330 nm nanobelts were obtained at 130 ºC and 3 atm. The results collaborate to the research on reformers for ethanol and/or solid oxide fuel cells anode.
Acesso aberto (Open Access)
Improvement of friable callus production of Boerhaavia paniculata Rich and the investigation of its lipid profile by GC/MS
(2014-09) SOUZA, Joanne Moraes de Melo; BERKOV, Strahill; SANTOS, Alberdan Silva
In this study, a protocol to induce high amount of friable callus of Boerhaavia paniculata RICH and a lipidomics technique were applied to investigate the profile of lipids to relate to those present in the roots of this plant that presented anti-inflammatory activity in the crude hexane extract. The callus culture was induced from seeds in solidified Murashige and Skoog medium containing different amounts of glucose and different concentrations of 2,4-Dichlorophenoxyacetic acid. The explants were kept in a germination chamber at 30±2°C with a photoperiod of 16 h under light intensity of 27 µmol m–2 s–1 for 4 weeks. The best results for friable callus formation and development of the biomass were obtained in the treatment containing 2.26 µM 2.4-D and glucose (1.5 %; w/v). Lipidomics techniques were applied in hexane fraction showing higher concentrations of the steroids β-sitosterol (3.53 mg/100 g dc–dry cells), and fatty acids, especially 2-hydroxy-tetracosanoic acid (0.34 mg/100 g dc), eicosanoic acid (86.25 mg/100 g dc), stearic acid (420.83 mg/100 g dc), tetradecanoic acid (10.74 mg/100 g dc) and linoleic acid (100.61 mg/100 g dc). The lipid profile of callus versus that found in the roots of wild plant is described in this work.
Acesso aberto (Open Access)
New isoflavones from the leaves of Vatairea guianensis Aublé
(2013-11) SOUZA, Ronilson Freitas de; MARINHO, Victor Hugo de Souza; SILVA, Geilson Alcantara da; COSTA JUNIOR, Livio Martins; SILVA, Joyce Kelly do Rosário da; BASTOS, Gilmara de Nazareth Tavares; ARRUDA, Alberto Cardoso; SILVA, Milton Nascimento da; ARRUDA, Mara Silvia Pinheiro
Four isoflavones were isolated from Vatairea guianensis Aublé leaves and identified as 5,3'-dihydroxy-4'-methoxy-2",2"-dimethylpyrano-(5",6":8,7)-isoflavone ( 1: ), 5,7-dihydroxy-3',4'-methylenedioxy-8-prenyl-isoflavone ( 2: ), 5,3'-dihydroxy-4'-methoxy-7-O-β-glucopyranoside-8-prenyl-isoflavone ( 3: ) and derrone ( 4: ) together with five triterpenes identified in mixture, lupeol, α-amyrin, β-amyrin, germanicol and betulinic acid. Substances 1: 3: are novel natural products, although 1: and 2: have been cited as synthetic products. However, all these compounds are first reported from this species. Their chemical structures were elucidated based on their 1D and 2D nuclear magnetic resonance (NMR) data and high resolution mass spectrometry. The ethanol extract from the leaves and 1: 3: were evaluated for their potential in scavenging DPPH• (2,2-diphenyl-1-picrylhydrazylradical) and the results showed that the extract presented high activity (IC50 = 6.2 ± 0.4 µg mL-1), while the isolated compounds showed low antioxidant power (IC50 ≥ 29.5 ± 2.5 µg mL-1) when compared to Trolox (IC50 = 4.5 ± 0.4 µg mL-1).
Acesso aberto (Open Access)
Estudo da utilização do extrato aquoso de barbatimão (Stryphnodendron barbatimão, M.) no ensino de química
(1999) PINHEIRO, Marta Helena Tavares; LIMA, Waterloo Napoleão de
In the present work, the pH dependent colour change of the crude vegetal extracts is suggested in teaching chemical or acid-base equilibria, visual indicators and some aspects of spectrophotometric concepts its applications. The extraction methodology proposed is inexpensive and easy to perform in secondary schools and in general chemistry or instrumental undergraduate courses.
Acesso aberto (Open Access)
Flavonoids from the leaves of Deguelia utilis (Leguminosae): structural elucidation and neuroprotective properties
(2012-10) OLIVEIRA, Dalglish Gomes de; ALMEIDA, Cecília M. C. de; SILVA, Consuelo Yumiko Yoshioka e; ARRUDA, Mara Silvia Pinheiro; ARRUDA, Alberto Cardoso; LOPES, Dielly Catrina Favacho; YAMADA, Elizabeth Sumi; COSTA, Edmar Tavares da; MARTINS FILHO, Arnaldo Jorge; SILVA, Milton Nascimento da
Five new flavonoids, 5,3'-dihydroxy-4'-methoxy-2'',2''-dimethylchromene-(5'',6'':6,7)dihydroflavonol (1), 5,3'-dihydroxy-7,4'-dimethoxy-6,8-dimethylallyl-dihydroflavonol (2), 5,3'-dihydroxy-4'-methoxy-8-allyl-2'',2''-dimethylchromene-(5'',6'':6,7) flavanone (3), 5,3'-dihydroxy-7,4'-dimethoxy-6,8-dimethylallyl-flavanone (4), 3,5,3'-trihydroxy-7,4'-dimethoxy6,8-dimethylallyl-flavanol (5), together with the stilbenes 4-methoxylonchocarpene (6) and lonchocarpene (7) were isolated from the leaves of Deguelia utilis. Their chemical structures were established on the basis of NMR (nuclear magnetic resonance) spectral data and HRESITOF-MS (electrospray ionization-high resolution time-of-flight mass spectrometry). Also, in order to investigate potential cytoprotective effects of these flavonoids, we used a fraction eluted with hexane:EtOAc containing all seven flavonoids, in an in vitro model of neurodegeneration, using hippocampal primary cultures from neonatal (PND2-P3) rats exposed to rotenone, a mitochondrial complex I inhibitor. There was a significant reduction in cell viability (19.4 ± 1.6%) when the cultures were exposed to 30 nmol L-1 rotenone for 72 h. Concomitant exposure of the cultures to the FR3 (5 µg mL-1) and 30 nmol L-1 rotenone resulted in values of cell viability similar to control groups (99.6 ± 4.8%), strongly suggesting a cytoprotective effect for this flavonoid-rich fraction.
Acesso aberto (Open Access)
Efeito fungitóxico in vitro do óleo resina e do óleo essencial de copaíba (Copaifera multijuga Hayne)
(2009) DEUS, Ricardo Jorge Amorim de; CARVALHO, Antonio Sergio Costa; BANNA, Débora Ariane Dornelas da Silva; ARRUDA, Mara Silvia Pinheiro; ALVES, Claudio Nahum; SANTOS, Alberdan Silva
In vitro fungitoxic effect of the oil-resin and the essential oil of copaiba (Copaifera multijuga Hayne). Copaifera multijuga Hayne oil, crude and fractions, was evaluated for its in vitro fungitoxic activities against five species of filamentous fungi belonging to the genus Aspergillus and three yeast species of the genus Candida. Oil-resin and essential oil concentrations ranging from 0.008 mg mL-1 to 1.6 mg mL-1 were used in qualitative and quantitative analyses. Samples were placed onto 5mm-diameter paper disks and distributed on Saboraud culture medium in Petri dishes inoculated with conidia and incubated at 28ºC during 10 days. A solution with 1.6 mg mL-1 of miconazole nitrate was used as positive control. Qualitative results indicated that the oil-resin presented good fungistatic activity; however, one of the essential oil fractions was highly effective against Candida parapsilosis IOC-2882, Aspergillus flavus IOC-3874 and A. tamarii IOC- 187, with inhibition halos of 16.0±1.4 mm, 19.5±2.1 mm and 12.5±3.5 mm, respectively. The quantitative evaluation indicated that 0.3 mg mL-1 of the oil-resin inhibited Aspergillus flavus and Candida parapsilosis growth, whereas 0.08 mg mL-1 of the essential oil fraction reached this same activity.