Navegando por Autor "Barbosa, L. C. A."
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Item Antibacterial and antiproliferative activities of the fresh leaf essential oil of Psidium guajava L. (Myrtaceae)(Brazilian Journal of Biology, 2018) Silva, E. A. J.; Estevam, E. B. B.; Silva, T. S.; Nicolella, H. D.; Furtado, R. A.; Alves, C. C. F.; Souchie, E. L.; Martins, C. H. G.; Tavares, D. C.; Barbosa, L. C. A.; Miranda, M. L. D.This study evaluated the antibacterial and antiproliferative activities of the essential oil of Psidium guajava leaves (PG-EO), traditionally used in folk medicine. The essential oil was obtained from fresh leaves by hydrodistillation, using a modified Clevenger apparatus. The major PG-EO chemical constituents were identified by GC-MS and GC-FID as being β-caryophyllene (16.1%), α-humulene (11.9%), aromadendrene oxide (14.7%), δ-selinene (13.6%), and selin-11-en-4α-ol (12.5%). The antibacterial activity of the essential oil of P. guajava leaves was determined in terms of its minimum inhibitory concentrations (MIC) using the broth microdilution method in 96-well microplates. PG-EO had moderate activity against Streptococcus mutans (MIC = 200 µg/mL), S. mitis (MIC = 200 µg/mL), S. sanguinis (MIC = 400 µg/mL), S. sobrinus (MIC = 100 µg/mL), and S. salivarius (MIC = 200 µg/mL). The antiproliferative activity was evaluated against different tumor cell lines: breast adenocarcinoma (MCF-7), human cervical adenocarcinoma (HeLa), and human gliobastoma (M059J). A normal human cell line (GM07492A, lung fibroblasts) was included. The antiproliferative activity was evaluated using the XTT assay and the results were expressed as IC50. The essential oil showed significantly lower IC50 values against MCF-7 and M059J lines than that obtained for the normal line, showing selectivity. Our results suggest that the essential oil of Psidium guajava L. has promising biological activities and can be considered a new source of bioactive compounds.Item Essential oils from pequi fruits from the brazilian Cerrado ecosystem(Food Research International, 2013-11) Geőcze, K. C.; Barbosa, L. C. A.; Fidêncio, P. H.; Silvério, F. O.; Lima, C. F.; Barbosa, M. C. A.; Ismail, Fyaz M. D.The composition of the essential oils of pequi fruits gathered from the Brazilian Cerrado ecosystem in the states of Maranhão (MA), Minas Gerais (MG) and Tocantins (TO) was investigated. The oils were obtained by steam distillation, and each component was speciated using GC-MS. The oil content varied from 0.13% to 1.15%. Interestingly, the major substance found within samples from two of the states was ethyl hexanoate (MA, MG), whereas isopropyl hexanoate and isopentyl-2-methylbutanoate were specific for the samples from TO. Both principal components analysis (PCA) and hierarchical cluster analysis (HCA) were used for exploratory analysis of the oils, and, consequently, the pequi fruits were classified according to their place of origin. The PCA showed that 51.5% of the variance accumulated in the PC1 and PC3, and the group formation obtained using HCA confirmed that the oil composition is influenced by geographic and/or plant genetic factors. Such analyses could assist in the selection of more flavoursome and healthy variants of pequi.Item Influence of hydrogen bonds on the molecular structure and conformations of two (C30H48O2) pentacyclic triterpene isomers(Journal of Structural Chemistry, 2012-02) Barbosa, L. C. A.; Corrêa, R. S.; Silva, S. R. Souza e; Duarte, L. P.; Silva, G. D. F.; Ellena, J.; Doriguetto, A. C.The structural study of two (C30H48O2) pentacyclic triterpene (PCTT) isomers is presented. These terpenes, known as 30-hydroxy-lup-20(29)-en-3-one (1) and (11α)-11-hydroxy-lup-20(29)-en-3-one (2), were isolated from Maytenus imbricata Mart. Ex Reissek (Celastraceae). The molecular structure of 1 and 2 differs in the position of the hydroxyl group. Both compounds crystallize in non-centrosymmetric space groups with two molecules in the asymmetric unit. The crystal structure of 1 shows a triclinic P1 space group (a = 9.5518(1) Å, b = 9.7083(1) Å, c = 14.4696(2) Å, α = 93.832(1)°, β = 102.833(1)°, and γ = 103.307(1)°), while compound 2 crystallizes in a monoclinic P21 one (a = 13.4439(16) Å, b = 14.4463(14) Å, c = 13.5224(9) Å and β = 99.703(8)°). The two molecules independent by symmetry of 1 differ slightly due to the presence of static disorder in oxygen atoms. In addition, the intermolecular geometries of 1 and 2 were analysed, and in each isomer the crystal packing is stabilized by O-H…O intermolecular hydrogen bonds and van der Waals forces.Item Synthesis and TGA evaluation of novel triphosphate esters(Journal of Fire Sciences, 2007-05) Barbosa, L. C. A.; Kiran, Y. B.; Gunasekar, D.; Raju, C. Naga; Marney, D. C. O.; Reddy, C. Devendranath; Russell, L. J.Several new substituted organo tri/thiotriphosphate esters were synthesized by condensing cyclic oxaza/dioxaphosphorochloridates/thiochloridates with [K.sub.2]HP[O.sub.4] in the presence of tetrabutylammonium iodide. The functionality on the phosphate was systematically changed by synthesis, thus allowing evaluation and comparison of a range of phosphate esters with highly varied structural features. They were subjected to thermogravimetric analysis, derivative thermogravimetric analysis, and differential thermal analysis to assess their thermal stability and potential use as flame retardants. It has been found that their thermal degradations, being highly complex and dependent upon a number of molecular structural features, are difficult to rationalize on simple rules.Item Variação de caracteres morfológicos e fisiológicos de populações naturais de Pfaffia glomerata (Spreng.) Pedersen e correlação com a produção de β-ecdisona(Revista Brasileira de Plantas Medicinais, 2009) Barbosa, L. C. A.; Cruz, C. D.; Otoni, W. C.; Kamada, T.; Vieira, R. F.; Picoli, E. A. TNo presente estudo, objetivou-se avaliar a divergência genética de indivíduos de quatro populações de fáfia [Pfaffia glomerata (Spreng.) Pedersen] coletadas na região do rio Paraná por meio de estudos de caracteres morfológicos associados à produção de β-ecdisona. A divergência foi avaliada entre 64 indivíduos utilizando 14 caracteres morfológicos quantitativos, incluindo o teor de β-ecdisona. Os dados foram interpretados pelas médias dos caracteres, índice de dissimilaridade de Mahalanobis, agrupamento pelo método UPGMA e correlação simples de Pearson. Os resultados demonstraram maiores valores de divergência entre indivíduos pertencentes a diferentes populações e menores, entre indivíduos da mesma população. Os indivíduos pertencentes à população 1, coletados à margem do rio Ivaí, destacaram-se pelos altos valores de β-ecdisona, predominando o seguinte perfil: matéria seca da raiz abaixo da média geral (135,1 g planta-1); antese precoce em relação a média geral (135,8 dias); dias para ocorrer a senescência de 90% das folhas abaixo da média geral (201,4 dias); e intervalo entre antese e senescência acima da média (65,6 dias). Os caracteres avaliados demonstraram significativa variação entre os indivíduos, no entanto, não foi possível observar dados que evidenciam a correlação entre a produção de β-ecdisona e caracteres morfológicos avaliados no presente estudo.