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Search Results: 1 - 10 of 325370 matches for " Alberdan S.; "
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Levels of As, Cd, Pb and Hg found in the hair from people living in Altamira, Pará, Brazil: environmental implications in the Belo Monte area
Carvalho, Antonio S. C.;Santos, Alberdan S.;Pereira, Simone F. P.;Alves, Cláudio N.;
Journal of the Brazilian Chemical Society , 2009, DOI: 10.1590/S0103-50532009000600022
Abstract: human hair was used as a bioindicator to evaluate the levels of as, cd, pb and hg in the resident population of the "volta grande" area of the xingu river, in the north of brazil. the concentrations of as and cd are in agreement with the values found in the literature, however, the pb and hg concentration is very different, which can suggest an inter-regional variation. moreover, the high values found for these elements in the residents of the canteiro island can be attributed to environmental exposure of this population in an area with environmental impact from activities of gold mining. the application of these methods showed that the concentrations of the metals studied in this work can correctly classify two different localities in the altamira district. the results reflect the impact of these elements on the health of the inhabitants of this auriferous area.
Preparation and assessment cytotoxic and hemolytic activities of Complexes from “Chelating Kojic–Lipid Conjugate”
Ant?nio S. C. Carvalho,Raquel C. Montenegro,Alberdan S. Santos
Orbital : the Electronic Journal of Chemistry , 2012,
Abstract: Complex bis (2-Oleicoyloxymethyl-5-hydroxy-gamma-pyrone) copper (II) and tris (2-Oleicoyloxymethyl-5-hydroxy-gamma-pyrone) iron (III) were prepared in ethanol using the structure "chelator conjugate kojic -lipid". This ester was obtained from kojic acid by improving their lipophilicity of obtaining metalobioactives with application in Medicinal Bioinorganic Chemistry. Through the technique ATR/FTIR, the values of the infrared kojic acid has been updated and it was possible to characterize the complex 1567m, 1511w (Cu (II)←[O=C]2), and 1540m, 1519m (Fe(III)←[O=C]3. These compounds no showed cytotoxic potential against B16 (melanoma) and ACP02 (gastric adenocarcinoma) (IC50> 5 μg mL-1) and low hemolytic activity (EC50> 250 μg mL-1).The preparation of these new molecules by structural modification techniques and these interesting biological results confirm the continuity of this studies related to these coordination complexes to glimpse the possibility of obtaining other derivatives/ analogues with significant biological potential of this metallo-bioactive.
Biotransformation of sucrose into 5-hydroxy-2-hydroxymethyl-γ-pirone by Aspergillus flavus
Ferreira, Nelson R.;Sarquis, Maria Inez M.;Alves, Cláudio N.;Santos, Alberdan S.;
Anais da Academia Brasileira de Ciências , 2010, DOI: 10.1590/S0001-37652010000300004
Abstract: the sucrose hydrolysis and the preference of consumption of glucose instead of fructose were investigated for the production of 5-hydroxy-2-hydroxymethyl-γ-pyrone (hhmp) in the presence of aspergillus flavus ioc 3974 cultivated in liquid czapeck medium. standardized 0.5g of pellets were transferred as inoculum into twelve conical flasks of 250 ml containing 100 ml of medium with different sucrose concentration, which was kept at 120 rpm and 28"c for 16 days without ph adjustment. aliquots of 500μl of the broth culture were withdrawn at 24 h intervals and analyzed. the major yield of hhmp was 26g l-1 in 120g l-1 of sucrose. at these conditions, a. flavus produced an invertase capable of hydrolyzing 65% of total sucrose concentration in 24h, and an isomerase capable of converting fructose into glucose. in this work, it focused the preference for glucose and, then, of fructose by a. flavus and the strategy used to produce hhmp.
Study of the Complex Stiffness of a Vibratory Mechanical System with Shape Memory Alloy Coil Spring Actuator
Samuell A. Holanda,Antonio A. Silva,Carlos J. de Araújo,Alberdan S. de Aquino
Shock and Vibration , 2014, DOI: 10.1155/2014/162781
Abstract: The vibration control is an important area in the dynamic of structures that seeks to reduce the amplitude of structural responses in certain critical frequency ranges. Currently, the scientific development leads to the application of some actuators and sensors technologically superior comparing to the same features available on the market. For developing these advanced sensors and actuators, smart materials that can change their mechanical properties when subjected to certain thermomechanical loads can be employed. In this context, Shape memory alloys (SMAs) may be used for developing dynamic vibration dampers which are capable of acting on the system providing proper tuning of the excitation frequency and the natural frequency. This paper aims to analyze the behavior of the stiffness and damping of a SMA helical coil spring actuator coupled to a mechanical system of one degree of freedom (1 DOF) subjected to an unbalanced excitement force and a temperature control system. By analyzing the effect of these parameters on the structural response and considering the concept of complex stiffness, it can be possible to predict the system's behavior within certain acceptable ranges of vibration, already in the design phase. 1. Introduction In the current stage of scientific and technological development, design of structures becomes increasingly complete and comprehensive to meet the diverse performance requirements. Among these requirements, we highlight the need for increasingly lighter and resilient structures, dynamic behavior to ensure stability and accuracy, and attenuation of vibrations to ensure the structural integrity and better comfort [1]. Structural systems are constantly susceptible to excitations that can lead to mechanical vibrations. These vibrations are in most cases undesirable, because they can endanger the structural integrity of the system itself and, in some cases, the safety of users. Recently, shape memory alloys (SMA) appear as potentially viable actuators for vibration control. The shape memory effect, superelasticity, and changes of mechanical properties with temperature allow the application of these smart materials in various fields of engineering [2]. However, the behavior of SMA is nonlinear, which makes its modeling and numerical simulation more complex, since the changes of parameters such as temperature and excitation frequency should be considered. This behavior requires further study to determine the intrinsic characteristics of SMA such as complex stiffness, which considers the energy dissipation per cycle and the
Avalia??o de minerais em plantas medicinais amaz?nicas
Martins, Alexsandro Sozar;Alves, Cláudio Nahum;Lameira, Osmar A.;Santos, Alberdan S.;Müller, Regina Celi Sarkis;
Revista Brasileira de Farmacognosia , 2009, DOI: 10.1590/S0102-695X2009000400020
Abstract: the amazonian brazilian offers an appreciable potential of plants with therapeutic properties, although most are little known. in this way, with the objective of verifying the potentiality nutritional of medicinal herbs, a work was developed to determine the concentration of ca, mg, fe, cu and zn in the leaves and in the teas of these species: piper callosum ruiz & pav., piperaceae, mikania lindleyana dc., asteraceae e arrabidaea chica (humb. & bonpl.) b. verl., bignoniaceae. after the plants samples have been processed, they were submitted to digestion and soon afterwards the metals were analyzed in an spectrophotometer of atomic absorption. the results showed the follow yields: for the tea of arrabidaea chica ca were detected (6955 to 20058 mg/l), mg (2390 to 3094 mg/l) and fe (40 to 61 mg/l). for the tea of mikania lindleyana besides the presence of high values of ca (17722 to 22336 mg/l), mg (4531 to 9370 mg/l) and fe (20 to 87 mg/l) they were found from 7 to 16 mg/l of cu and 9 to 41 mg/l of zn. the tea of the piper callosum presented 2036 to 4344 mg/l of ca, 618 to 4023 mg/l of mg and 39 to 60 mg/l of fe. being compared the results of the minerals with the values recommended by the health world organization, is possible that the present metals in the teas of the plants could contribute in the complementation of the people's alimentary diets that use these medicinal plants.
A Novel Function for Kojic Acid, a Secondary Metabolite from Aspergillus Fungi, as Antileishmanial Agent
Ana Paula D. Rodrigues, Luis Henrique S. Farias, Antonio Sérgio C. Carvalho, Alberdan S. Santos, José Luiz M. do Nascimento, Edilene O. Silva
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0091259
Abstract: Kojic acid (KA) is a fungal metabolite used as a topical treatment skin-whitening cosmetic agent for melasma in humans; however its potential as an anti-leishmanial agent is unknown. Chemotherapy is one of the most effective treatments for Leishmaniasis. However, the drugs available are expensive, invasive, require long-term treatment and have severe side effects. Thus, the development of new effective leishmanicidal agents is a necessity. In this study we investigated the anti-leishmanial effect of KA on L. amazonensis, following in vitro and in vivo infections. KA (50 μg/mL) was found to decrease the growth by 62% (IC50 34 μg/mL) and 79% (IC50 27.84 μg/mL) of promastigotes and amastigotes in vitro, respectively. Ultrastructural analysis of KA-treated amastigotes showed the presence of vesicles bodies into the flagellar pocket, and an intense intracellular vacuolization and swelling of the mitochondrion. During the in vitro interaction of parasites and the host cell, KA reverses the superoxide anions (O2-) inhibitory mechanism promoted by parasite. In addition, 4 weeks after KA-topical formulation treatment of infected animals, a healing process was observed with a high production of collagen fibers and a decrease in parasite burden. Thus, these results demonstrated the great potential of KA as an anti-leishmanial compound.
Stilbenes from Deguelia rufescens var. urucu (Ducke) A. M. G. Azevedo leaves: effects on seed germination and plant growth
Lobo, Lívia T.;Silva, Geilson A. da;Freitas, Manolo C. C. de;Souza Filho, Antonio Pedro S.;Silva, Milton N. da;Arruda, Alberto C.;Guilhon, Giselle M. S. P.;Santos, Lourivaldo S.;Santos, Alberdan S.;Arruda, Mara S. P.;
Journal of the Brazilian Chemical Society , 2010, DOI: 10.1590/S0103-50532010001000007
Abstract: the amazon biodiversity may provide plants whose chemical substances are capable of controlling weeds. in this study we report the isolation and identification of five stilbenes from the leaves of "timbó vermelho" (deguelia rufescens var. urucu): 4-methoxylonchocarpene (1); 3,5-dimethoxy-4′-hydroxy-3′-prenyl-trans-stilbene (2), lonchocarpene (3), 3,5-dimethoxy-4′-o-prenyl-trans-stilbene (4) and pterostilbene (5). compounds 2 and 4 are new natural products although 2 has been previously cited as synthesis product. potential allelopathic activity for 1, 2 and 4 was evaluated over seed germination and plant growth of mimosa pudica weed. the observed effects on seed germination did not vary significantly (p > 0.05) when the analysis of phytotoxicity was performed with the substances alone, the maximum inhibition did not exceed 20%. the most intense inhibitions on radicle and hypocotyl development were found for compound 4 (p < 0.05). when tested in pairs, showed antagonism for seed germination and synergism for radicle and hypocotyl development.
Antraquinonas e naftoquinonas do caule de um espécime de reflorestamento de Tectona grandi (Verbenaceae)
Moreira, Rafael Y.O.;Arruda, Mara S.P.;Arruda, Alberto C.;Santos, Lourivaldo S.;Müller, Adolfo H.;Guilhon, Giselle M.S.P.;Santos, Alberdan S.;Terezo, Evaristo;
Revista Brasileira de Farmacognosia , 2006, DOI: 10.1590/S0102-695X2006000300017
Abstract: the hexane extract of the bark of tectona grandis (verbenaceae) afforded two anthraquinones and two naphtoquinones. their caracterizations were obtained through nmr spectroscopic techniques. this is the first phytochemical study of the bark of tectona grandis reforestation specimen in brazil. the main interest in this work is proving the presence of tectoquinone in reforestation specimen.
Dihydroflavonols from the leaves of Derris urucu (Leguminosae): structural elucidation and DPPH radical-scavenging activity
L?bo, Lívia T.;Silva, Geilson A. da;Ferreira, Malisson;Silva, Milton N. da;Santos, Alberdan S.;Arruda, Alberto C.;Guilhon, Giselle M. S. P.;Santos, Lourivaldo S.;Borges, Rosivaldo dos Santos;Arruda, Mara Silvia P.;
Journal of the Brazilian Chemical Society , 2009, DOI: 10.1590/S0103-50532009000600013
Abstract: derris urucu is an amazonian plant with insecticide and ichthyotoxic properties. studies with this species show the presence of flavonoids, mainly rotenoids, as well as stilbenes. the ethanol extract of the leaves of derris urucu (leguminosae) afforded three new dihydroflavonols named urucuol a (1), b (2) and c (3), and the dihydroflavonol isotirumalin (4). their structures were elucidated by extensive analysis of 1d and 2d nmr, uv and ir spectra and ms data and comparison with literature data. the isolated compounds (1-4) were evaluated for dpph? radical scavenging activity and showed a relatively lower antioxidant ability compared to the commercial antioxidant trans-resveratrol.
Biotransformation of chalcones by the endophytic fungus Aspergillus flavus isolated from Paspalum maritimum trin
Corrêa, Marivaldo J. C;Nunes, Fátima M;Bitencourt, Heriberto R;Borges, Fábio C;Guilhon, Giselle M. S. P;Arruda, Mara S. P;Marinho, Andrey M. R;Santos, Alberdan S;Alves, Cláudio N;Brasil, Davi S. B;Santos, Lourivaldo S;
Journal of the Brazilian Chemical Society , 2011, DOI: 10.1590/S0103-50532011000700019
Abstract: the fungus aspergillus flavus isolated as endophytic of the plant paspalum maritimum trin. was evaluated for its potential application in biotransformation reactions. the compounds chalcone (1), 3,4,5-trimethoxychalcone (2) and 2,3,4,4'-tetramethoxychalcone (3) were biotransformed, respectively, in dihydrochalcone (4), 3,4,5-trimethoxydihydrochalcone (5) and 2,3,4,4'-tetramethoxydihydrochalcone (6). the structures were elucidated by spectroscopic methods including 1d and 2d nmr techniques, and ms analysis. the dihydrochalcones 5 and 6 are new compounds.
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