Navegando por Autor "Barbosa, Luiz Cláudio de Almeida"
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Item Chemical variation in the essential oil of Hyptis suaveolens (L.) Poit., under cultivation condition(Química Nova, 2006-07-25) Barbosa, Luiz Cláudio de Almeida; Martins, Felipe Terra; Santos, Marcelo Henrique dos; Polo, MarceloThis study was performed to establish the correlation between the growth conditions and essential oil composition of Hyptis suaveolens from Alfenas (MG), Brazil. The plants were grown in a greenhouse, four treatments were used and they were harvested at two different periods of time (60 and 135-day-old plants). The essential oil composition was determined by GC-MS analysis. The terpenes spathulenol, globulol, dehydroabietol, a-cadinol and b-phellandrene were the major constituents found in the essential oil. Oxygenated sesquiterpenes represented the main group of constituents in most of the treatments. The major changes in the essential oil composition were found in 135-day-old plants grown under NPK deficiency. We also identified three groups of volatile components that have not been previously described in H suaveolens.Item A comparative study on the crystal structure of bicycle analogues to the natural phytotoxin helminthosporins(Journal of Molecular Structure, 2016-02-05) Barbosa, Luiz Cláudio de Almeida; Teixeira, Robson Ricardo; Nogueira, Leonardo Brandão; Maltha, Celia Regina Alvares; Doriguetto, Antônio Carlos; Martins, Felipe TerraHerein we described structural insights of a series of analogues to helminthosporin phytotoxins. The key reaction used to prepare the compounds corresponded to the [3 + 4] cycloaddition between the oxyallyl cation generated from 2,4-dibromopentan-3-one and different furans. Their structures were confirmed upon IR, NMR and X-ray diffraction analyses. While bicycles 7, 8 and 9 crystallize in the centrosymmetric monoclinic space group P21/c, compound 10 was solved in the noncentrosymmetric orthorhombic space group P212121. The solid materials obtained were shown to be racemic crystals (7, 8, 9) or racemic conglomerate (10). In all compounds, there is formation of a bicycle featured by fused tetrahydropyranone and 2,5-dihydrofuran rings. They adopt chair and envelope conformations, respectively. Crystal packing of all compounds is stabilized through C–H•••O contacts. Conformational aspects as well as similarities and differences among the crystal structures of the synthesized analogues are discussed.Item Composição e fungitoxicidade do óleo essencial de capim citronela em função da adubação orgânica(Pesquisa Agropecuária Brasileira, 2012-10-23) Barbosa, Luiz Cláudio de Almeida; Veloso, Ronice Alves; Castro, Henrique Guilhon de; Cardoso, Dione Pereira; Santos, Gil Rodrigues dos; Silva, Kamilla Pires daO objetivo deste trabalho foi avaliar a influência da adubação orgânica sobre o teor e a composição do óleo essencial de capim citronela (Cymbopogon nardus), bem como a fungitoxicidade desse óleo ao crescimento micelial dos fungos Didymella bryoniae, Colletotrichum gloeosporioides e Amphobotrys ricini. A extração do óleo essencial foi realizada por hidrodestilação, a partir de plantas cultivadas em quatro doses de adubação orgânica (0, 3, 6 e 9 kg de esterco bovino curtido por cova), e a identificação dos constituintes químicos foi conduzida por cromatografia gasosa/espectrometria de massas. Para avaliar a inibição do crescimento micelial, o experimento foi instalado no delineamento inteiramente casualizado, em arranjo fatorial. Foram testadas sete alíquotas do óleo essencial (0, 5, 10, 15, 20, 25 e 30 µL), em cinco épocas de avaliação, com quatro repetições. O teor de óleo essencial do capim citronela não foi afetado pela adubação orgânica, e o óleo essencial do capim citronela apresentou 24 compostos químicos, entre estes monoterpenos e sesquiterpenos, com maior concentração dos compostos citronelal, β-citronelol, geraniol e elemol. O óleo essencial do capim citronela apresenta maior efeito de inibição a Amphobotrys ricini, em comparação aos fungos Didymella bryoniae e Colletotrichum gloeosporioides.Item Determinação de constituintes químicos em madeira de eucalipto por Pi-CG/EM e calibração multivariada: comparação entre redes neurais artificiais e máquinas de vetor suporte(Química Nova, 2011) Nunes, Cleiton Antônio; Lima, Claudio Ferreira; Barbosa, Luiz Cláudio de Almeida; Colodette, Jorge Luiz; Fidêncio, Paulo HenriqueMultivariate models were developed using Artificial Neural Network (ANN) and Least Square - Support Vector Machines (LS-SVM) for estimating lignin siringyl/guaiacyl ratio and the contents of cellulose, hemicelluloses and lignin in eucalyptus wood by pyrolysis associated to gaseous chromatography and mass spectrometry (Py-GC/MS). The results obtained by two calibration methods were in agreement with those of reference methods. However a comparison indicated that the LS-SVM model presented better predictive capacity for the cellulose and lignin contents, while the ANN model presented was more adequate for estimating the hemicelluloses content and lignin siringyl/guaiacyl ratio.Item Discrimination between workers of Acromyrmex subterraneus molestans from monogynous and polygynous colonies(Brazilian Archives of Biology and Technology, 2006-03) Souza, Danival José de; Lucia, Terezinha Maria Castro Della; Barbosa, Luiz Cláudio de AlmeidaBehavioral assays were conducted with individuals from monogynous and polygynous colonies of Acromyrmex subterraneus molestans to evaluate the discriminatory ability of ant workers. These bioassays showed that this subspecies could not discriminate among non-nestmates or nestmate workers. However, nestmates of these same colonies did discriminate among workers of another subspecies Ac. subterraneus subterraneus. When discrimation occurred there were no differences in the response of workers from either monogynous or polygynous colonies. Similarities or differences in the chemical profile of both subspecies explained the absence or occurence of aggressiveness among workers. The chemical profile of colonies of the same subspecies was very similar among them, although distinct among subspecies. The number of queens did not influence the cuticular chemical composition of the workers or their behavior.Item Diversidade genética entre acessos de mentrasto avaliada por características botânico-agronômicas, moleculares e fitoquímicas(Revista Ceres, 2004-03) Silva, Derly José Henriques da; Castro, Henrique Guilhon de; Oliveira, Luiz Orlando de; Ferreira, Francisco Affonso; Sakiyama, Ney Sussumu; Barbosa, Luiz Cláudio de Almeida; Ribeiro Júnior, José IvoObjetivou-se avaliar a divergência genética entre cinco acessos de mentrasto por métodos multivariados, utilizando-se características botânico-agronômicas, moleculares (marcadores RAPD) e fitoquímicas (teor e composição do óleo essencial). A análise de agrupamento por meio do método de Tocher, das características botânico-agronômicas, moleculares e fitoquímicas, formou dois grupos. Na análise da divergência genética por marcadores moleculares, 14 primers deram origem a 26 bandas polimórficas. A biomassa fresca e & biomassa seca foram as características botânico- agronômicas que mais contribuíram para a diversidade genética. As características fitoquímicas que mais contribuíram para a diversidade genética foram os compostos precoceno I e precoceno ll. Verificou-se coeficiente de correlação significativo entre biomassa seca e precoceno I. Foram constatados coeficientes de correlação não-significativos entre as características botânico-agronômicas, moleculares e fitoquímicas, com base nas distâncias dos acessos.Item Efeito da temperatura do ar de secagem sobre a qualidade do óleo essencial de Mikania glomerata(Effect of drying air temperature on the quality of essential oil from Mikania glomerata, 2013-12-31) Rocha, Ronicely Pereira; Melo, Evandro de Castro; Barbosa, Luiz Cláudio de Almeida; Radunz, Lauri LourençoThis study aimed to evaluate the influence of drying air temperature on the content of essential oil extracted from guaco. The drying tests were performed in an experimental fixed-bed dryer, which contains 4 perforated trays with upward air flow. Treatments consisted of five temperatures for the drying air (ambient air and air heated to 40, 55, 70 and 85oC), with three repetition, using 850 g of fresh guaco leaves. Guaco leaves were dried until reaching a final moisture content of approximately 10% w.b. The drying air velocity was 0.5 m s -1 . Essential oil extraction was performed by hydrodestilation, using Clevenger equipment. Results of the essential oil content showed that the drying air temperatures from 55 to 85oC did not statistically influence the essential oil content. The chromatographic profile of the essential oil presented changes as a function of the drying treatment when compared with the in natura plant (control).Item Essential oil in the taxonomy of Ocimum selloi Benth(Journal of the Brazilian Chemical Society, 1996-08-12) Martins, Ernane Ronie; Casali, Vicente Wagner Dias; Barbosa, Luiz Cláudio de Almeida; Carazza, FernandoChemical composition analysis of the essential oil from the leaves and flowers of two accessions of Ocimum selloi Benth, cultivated at the Federal University of Viçosa was carried out. For accession A the major component was identified as estragole and represented 94,95% and 92,54% of the oil from the leaves and flowers respectively. For accession B, the oil from the leaves and flowers was constituted by 65,49% and 66,18% of methyleugenol, respectively. For both accessions several minor constituents were also identified. The phenotypic and chemical differences observed between these two accessions suggest the existence of two chemicaly distinct varieties for Ocimum selloi Benth.Item Harvest time on the content and chemical composition of essential oil from leaves of guava(Ciência Rural, 2016-10) Silva, Elizabeth Aparecida Josefi da; Silva, Vanessa Paula da; Alves, Cassia Cristina Fernandes; Alves, José Milton; Souchie, Edson Luiz; Barbosa, Luiz Cláudio de AlmeidaThe essential oil plants contents can be affected by several factors. For example, in certain plants, collection time has been observed to affect the content and chemical composition of the essential oil obtained from the plant. The objective of this study was to evaluate the effect of collection time on the content and chemical composition of the essential oil from guava ( Psidium guajava L.) leaves. Leaves were collected at different times of the day and the content and chemical composition of their essential oil was determined. Collection time did not qualitatively affect the chemical composition of the essential oil. However, concentration of certain substances in the oil, such as α-humulene and trans-caryophyllene, did significantly vary at different collection times. The main constituents of the essential oil of Psidium guajava are limonene (2.2-4.4%), trans-caryophyllene (18.1-17.1%), α-humulene (26.3-20.4%), aromadendrene (7.6-12.2%), α-selinene (7.3-11.3%), caryophyllene oxide (3.7-3.3%), humulene epoxide II (4.1-1.9%), and selin-11-en-4α-ol (7.2-11.1%). Leaves collected at 7:00 AM had higher essential oil production, with a content of 0.38% (d.b.), whereas leaves collected at 7:00 PM had lower essential oil production, 0.24% (d.b.). Chemical analysis showed that sesquiterpene compounds represented the highest concentration (62.0%), and monoterpenoids and monoterpenes represented the lowest concentrations (1.1 and 2.2%, respectively). Chemical classes that underwent major changes with respect to collection time were monoterpenes, sesquiterpenes, and sesquiterpenoids (2.2-4.4%, 63.8-61.7%, and 15.9-13.2%, respectively).Item Influence of drying air temperature on the chemical composition of the essential oil of melaleuca(Engenharia na Agricultura, 2011-10-25) Lemos, Diana Rodrigues Herinque; Melo, Evandro de Castro; Rocha, Ronicely Pereira; Barbosa, Luiz Cláudio de Almeida; Pinheiro, Antonio LelisThis study was done to evaluate the influence of drying air temperature on the chemical composition of the essential oil of Melaleuca alternifólia Cheel. Three samples were taken at random from each treatment which were analyzed still fresh, determining the moisture content and chemical composition of the essential oil.The plants were chopped and placed in a fixed-bed dryer and dried with air temperature of 40, 50, 60, 70 and 80 °C. The identification of compounds was done using gas chromatography coupled to mass spectrometry. The major components of essential oil of melaleuca subjected to drying air temperatures of 40, 50, 60, 70 and 80 ° C were within the ISO Standard 4730, which classifies plant as medicinal or not.There was an increase in the levels of terpinen-4-ol and α-terpineol and decrease of α-pinene compared to the control.Item Influência do processo de secagem sobre os principais componentes químicos do óleo essencial de tomilho(Revista Ceres, 2012-07-16) Rocha, Ronicely Pereira da; Melo, Evandro de Castro; Barbosa, Luiz Cláudio de Almeida; Corbín, José Bon; Berbet, Pedro AmorimObjetivou-se, com este trabalho, avaliar o efeito da temperatura do ar de secagem sobre a qualidade do óleo essencial de folhas de tomilho. Foram empregadas diferentes temperaturas de secagem (30, 40, 50, 60, 70 ºC), em um secador com resistências elétricas. Os componentes químicos do óleo essencial, depois de realizada a secagem, foram comparados com os valores obtidos na planta in natura (testemunha). Para a extração do óleo essencial, foi empregado o método de extração com CO2 supercrítico. A identificação dos componentes químicos do óleo essencial foi realizada por cromatografia gasosa, acoplada ao espectrofotômetro de massas (CG-EM) e, para a quantificação desses componentes, empregou-se o cromatógrafo a gás, acoplado ao detector por ionização de chamas (CG-DIC). Em função dos resultados obtidos, recomenda-se ar, à temperatura de 60 ºC, para a secagem das folhas de tomilho.Item Isolamento e avaliação da atividade nematicida de constituintes químicos de Mucuna cinerea contra Meloidogyne incognita e Heterodera glycine(Química Nova, 2003-05) Demuner, Antonio Jacinto; Barbosa, Luiz Cláudio de Almeida; Nascimento, Jeferson Chagas do; Vieira, Jessy James; Santos, Maria Amelia dosPhytochemical investigation of the aerial parts and roots of Mucuna cinerea led to the isolation of a mixture of fatty acids, triacylglicerols, b-sitosterol, stigmasterol, stigmasterol glucoside, daucosterol, asperglaucide (4) and the isoflavonoids prunetin (1), genistein (2), medicarpin (3), daidzein (5), 7-O-a-glycopiranosyl daidzein (6). An in vitro bioassay was carried out with compounds 1-4, at the concentration of 50 and 5 mg mL-1 against the phytonematodes M. incognita and H. glycines. Although the four compounds showed some nematocidal property, the most active was (1), causing 70% mortality of M. incognita at the concentration of 50 mg mL-1.Item Metodologia de extração e determinaçao do teor de extrativos em madeiras de eucalipto(Revista Árvore, 2006-09-03) Barbosa, Luiz Cláudio de Almeida; Silvério, Flaviano Oliveira; Gomide, José Lívio; Reis, Fernando Pinheiro; Piló-Veloso, DorilaNeste trabalho foi avaliado o teor de extrativos em madeiras de eucalipto, por meio de extrações com acetona, mistura de tolueno:etanol (2:1), clorofórmio e diclorometano. As maiores porcentagens de extrativos totais foram obtidas ao utilizar acetona como solvente. Os extratos obtidos em acetona e tolueno:etanol foram ressuspendidos em diclorometano, para avaliação do teor de extrativos lipofílicos. As porcentagens desses extrativos foram semelhantes às obtidas com diclorometano ou clorofórmio, em extrações diretas. Os extratos foram analisados por espectroscopia no infravermelho, para identificação dos principais grupos funcionais dos constituintes extraídos.Item A pentacyclic triterpene from Maytenus imbricata: structure elucidation by X-ray crystallography(Structural Chemistry, 2006-02) Pimenta Jr., Alécio Antonio; Silva, Sílvia Ribeiro de Souza e; Silva, Grácia Divina de Fátima; Barbosa, Luiz Cláudio de Almeida; Ellena, Javier; Doriguetto, Antonio CarlosA pentacyclic triterpene, 3β,30-dihydroxy-lup-20(29)-ene, was isolated from the powder extract of Maytenus imbricata. The structure and stereochemistry of the compound were established by spectroscopic techniques and unambiguously determined by single crystal X-ray crystallography. The crystal structure shows one molecule in the asymmetric unit. The crystal packing is stabilized by O–H···O intermolecular hydrogen bonds, which give rise to infinite helical chains along the c unit cell axis. The intra-molecular geometry was analyzed using MOGUL, a knowledge base of molecular geometry derived from the Cambridge Structural Database (CSD).Item Phytogrowth-Inhibitory lactones derivatives of Glaucolide B(De Gruyter, 2014-06-02) Barbosa, Luiz Cláudio de Almeida; Costa, Adilson V.; Piló-Veloso, Dorila; Lopes, Joao Luiz C.; Hernandez-Terrones, Manuel G.; King-Diaz, Beatriz; Lotina-Hennsen, BlasThe sesquiterpene lactone glaucolide B (1), isolated from Vernonia fruticulosa (Asteraceae), was transformed into six lactones (2-7). The structures of the products were elucidated by spectroscopic analysis. A series of solutions of compounds 1-7, at 200 μᴍ, were tested on the germination and on the root and shoot growth of the dicotyledons Physalis ixocarpa and Trifolium alexandrinum and of the monocotyledons Lolium multiflorum and Amaranthus hypochondriacus. Lactone 5 exhibited clear selectivity towards dicotyledonous species at 200 μᴍ, with an average inhibition of 90% on the germination of P. ixocarpa. Lactones 1, 3 and 4 had a greater effect on root length of monocotyledonous species, inhibiting around 70% at 200 μᴍ in L. multiflorum. It seems that the diol function is required in lactones 4-6 to increase the activity, the polarity in the molecule might be required to reach its target.Item Phytotoxic effectes of metabolites from Alternaria euphorbiicola against its host plant Euphorbia heterophylla(Química Nova, 2013-05-24) Varejão, Eduardo Vinícius Vieira; Demuner, Antônio Jacinto; Barbosa, Luiz Cláudio de Almeida; Barreto, Robert WeingartA bioassay-guided fractionation of culture filtrates of the fungus Alternaria euphorbiicola, a pathogen of the weed Euphorbia heterophylla, led to the isolation of anhydromevalonolactone (1), tyrosol (2), (R)-( - )-mevalonolactone (3), and cycloglycylproline (4). When tested on the punctured leaves of the host plant, these compounds produced bleached lesions with dark brown margins at concentrations as low as 80 µM. When tested on the leaves of other relevant weeds, only cycloglycylproline showed selective activity against E. heterophylla. This is the first report on the isolation of phytotoxins from A. euphorbiicola and on the phytotoxicity of anhydromevalonolactone, (R)-( - )-mevalonolactone, and cycloglycylproline.Item Preparation and phytotoxicity of sorgoleone analogues(Química Nova, 2001-11) Barbosa, Luiz Cláudio de Almeida; Ferreira, Maria Lúcia; Demuner, Antonio Jacinto; Silva, Antonio Alberto da; Pereira, Rita de Cássia3,5-Dimethoxybenzylic alcohol was converted into the 2-acetoxy-5-methoxy-3-(pent-1-yl)-1,4-benzoquinone (12), in seven steps, with an overall yield of 14.6%. The natural quinone sorgoleone (1) was isolated from Sorghum bicolor and converted into the corresponding quinone (13) having a saturated side chain. The selective effects of these compounds (1, 12 and 13), at the dose of 5.6 mg of a.i./ g of substrate, on the growth of Cucumis sativus, Lactuca sativa, Desmodium tortuosum, Hyptis suaveolens and Euphorbia heterophylla were evaluated. All three compounds caused some inhibition on the root growth of the test plants (0.0-69.19%) with the aerial parts less affected. The results showed that the triene unit of the sorgoleone side chain is not essential for the phytotoxicity and also the synthetic quinone was as active as the natural product.Item Síntese de novos herbicidas derivados do 1, 2a, 4a, 5- tetrametil- 8- oxabiciclo[ 3. 2. 1] oct- 6- en- 3- ona(Química Nova, 2004-03) Barbosa, Luiz Cláudio de Almeida; Maltha, Célia Regina Álvares; Demuner, Antônio Jacinto; Filomeno, Claudinei Andrade; Silva, Antônio Alberto daIn this paper we report the synthesis of biologically active compounds through a [3+4] cycloaddition reaction to produce the main frame structure, followed by several conventional transformations. The 1,2a,4a,5-tetramethyl-8-oxabicyclo[3.2.1]oct-6-en-3-one (11) obtained from a [3+4] cycloaddition reaction was converted into 1,2a,4a,5-tetramethyl-6,7-exo-isopropylidenedioxi-8 -oxabicyclo[3.2.1]octan-3-one (13) in 46% yield. This was further converted into the alcohols 1,2a,4a,5-tetramethyl-6,7-exo-isopropylidenedioxi-8-oxabicyclo[3.2.1]octan-3 a-ol (14), 1,2a,4a,5-tetramethyl-6,7-exo-isopropylidenedioxi-8 -oxabicyclo[3.2.1]octan-3b-ol (15), 1,2a,4a,5-tetramethyl-3-butyl-6,7-exo-isopropylidenedioxi-8-oxabicyclo[3.2.1]octan-3 a-ol (17), 1,2a,4a,5-tetramethyl-3-hexyl-6,7-exo-isopropylidenedioxi-8-oxabicyclo[3.2.1]octan-3 a-ol (18) and 1,2a,4a,5-tetramethyl-3-decyl-6,7-exo-isopropylidenedioxi-8-oxabicyclo[3.2.1]octan-3 a-ol (19). Dehydration of 17, 18 and 19 with thionyl chloride in pyridine resulted in the alkenes 20, 21 and 22 in ca. 82% - 89% yields from starting alcohols. The herbicidal activity of the compounds synthesized was evaluated at a concentration of 100 µg g-1. The most active compound was 21 causing 42,7% inhibition against Cucumis sativus L.Item Síntese e avaliação da atividade fitotóxica de lactonas derivadas do 2, 4- dimetil- 8- oxabiciclo[ 3. 2. 1]- oct- 6- en- 3- ona(Química Nova, 2002-04) Barbosa, Luiz Cláudio de Almeida; Maltha, Célia Regina Álvares; Borges, Eduardo Euclides LimaThe alkene 2,4-dimethyl-8-oxabicyclo[3.2.1]-oct-6-en-3-one (3) was converted to 1,3,10-trimethyl-8-oxabicyclo[5.3.0]-dec-3-ene-2,9-dione (7) and 1,3-dimethyl-8-oxabicyclo[5.3.0]-dec-3-ene-2,9-dione (8) with a 55% overall yield in both cases. Lactones (7) and (8) were converted in two steps to 1,3,4-trimethyl-13-methylene-6-oxatricyclo[8.3.0.0 3,7]-trideca-2,5,12-trione (12) (63%) and 1,3-dimethyl-13-methylene-6-oxatricycle[8.3.0.0 3,7]-trideca-2,5,12-trione (13) (45% from 8). The effect of lactones (7), (8), (12), (13) and the intermediates (5) and (6), at the concentration of 250 mg mL-1, on the growth of Cucumis sativus L. and Sorghum bicolor L. was evaluated. The best results were observed for lactone (13) that caused 100% inhibition on the root growth of C. sativus and lactone (12) that inhibited 90% of the root growth for S. bicolor.Item Síntese e avaliação da atividade fitotóxica de novos análogos oxigenados do ácido helmintospórico(Química Nova, 2003-09) Barbosa, Luiz Cláudio de Almeida; Demuner, Antônio Jacinto; Maltha, Célia Regina Álvares; Silva, Patrícia Silvana da; Silva, Antônio Alberto daSeveral compounds related to helminthosporic acid (3) were synthesized via the [3+4] cycloaddition. The reaction of 3-hydroxymethyl-2-methylfuran (12) with 1,1,3,3-tetrabromo-4-methylpentan-2-one (13) resulted in 7-hydroxymethyl-4a-isopropyl-1a-methyl-8-oxabicyclo[3.2.1]oct-6-en-3-one (8) (37%) and 7-hydroxymethyl-2a-isopropyl-1a-methyl-8-oxabicyclo[3.2.1]oct-6-en-3-one (14) (12%), which were converted into 7-formyl-4a-isopropyl-1a-methyl-8-oxabicyclo[3.2.1]oct-6-en-3-one (16) (32% from 8) and 7-formyl-2a-isopropyl-1a-methyl-8-oxabicyclo[3.2.1]oct-6-en-3-one (18) (40% from 14), respectively. Reduction of (8) resulted in 7-hydroxymethyl-4a-isopropyl-1a-methyl-8-oxabicyclo[3.2.1]oct-6 -en-3a-ol (11) (63% from 8) and 7-hydroxymethyl-4a-isopropyl-1a-methyl-8-oxabicyclo[3.2.1]oct-6-en-3 b-ol (15) (30% from 8). The 4a-isopropyl-1a-methyl-3-oxo-8-oxabicyclo[3.2.1]oct-6-en-7-oic acid (19) was obtained by oxidation of (16) (78%). The results of biological tests are described in details. The best result was observed for compound (15) that caused 76% inhibition on the root growth of D. tortuosum.