31 resultados para Natural compound


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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Brazil has many species of spiders belonging to Araneidae family however, very little is known about the composition, chemical structure and mechanisms of action of the main venom components of these spiders. The main objective of this work was to isolate and to perform the chemical characterization of a novel beta-carboline toxin from the venom of the spider Parawixia bistriata, a typical species of the Brazilian 'cerrado'. The toxin was purified by RP-HPLC and structurally elucidated by using a combination of different spectroscopic techniques (UV, ESI-MS/MS and H-1 NMR), which permitted the assignment of the molecular structure of a novel spider venom toxin, identified as 1-4-guanidinobutoxy-6-hydroxy-1,2,3,4-tetrahydro-beta-carboline, and referred to here as PwTx-II. This compound is toxic to insects (LD50 = 12 +/- 3 eta g/mg honeybee), neurotoxic, convulsive and lethal to rats (LD50 = 9.75 mg/kg of male Wistar rat). (c) 2005 Elsevier Ltd. All rights reserved.

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Pós-graduação em Ciências Odontológicas - FOAR

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Three naturally occurring isocoumarins (paepalantine, paepalantine 9-O-beta-D-glucopyranoside and paepalantine 90-beta-D-allopyranosyl(1 -> 6) glucopyranoside) and two semi-synthetic analogues, 9,10-acylated compound and 9-OH-10-methylated compound,. structurally similar to paepalantine, were evaluated for antimicrobial activity using a spectrophotometric microdilution technique. The paepalantine was active against S. aureus, S. epidermidis, and E faecalis. while the other four compounds proved ineffective against all microorganisms tested at concentrations of 500 mu g/ml. Variations in phenolic substitution at OH-9 and/or OH-10 in the paepalantine molecule resulted in compounds without antimicrobial activity. A combination of structural features, two phenolic groups as cathecolic system, forms an oxygenated system arrangement that may reflect the potentially antimicrobial properties of paepalantine. (c) 2004 Elsevier GmbH. All rights reserved.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Five new piperidine alkaloids were designed from natural (-)-3-O-acetyl-spectaline and (-)-spectaline that were obtained from the flowers of Senna spectabilis (sin. Cassia spectabilis, Leguminosae). Two semi-synthetic analogues (7 and 9) inhibited rat brain acetylcholinesterase, showing IC50 of 7.32 and 15.1 mu M, and were 21 and 9.5 times less potent against rat brain butyrylcholinesterase, respectively. Compound 9 (1 mg/kg, ip) was fully efficacious in reverting scopolamine-induced amnesia in mice. The two active compounds (7 and 9) did not show overt toxic effects at the doses tested in vivo. (c) 2005 Elsevier Ltd. All rights reserved.

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Sunflower oil (SO) and high-oleic sunflower oil (HOSO) were used to prepare fried potatoes by either discontinuous or continuous laboratory frying. Fried potatoes that had been fried in oils of differing quality were stored at 60 degrees C for up to 30 d and evaluated for polar compounds, polymers, peroxide value, oil stability index, and alpha-tocopherol content. Results obtained through the various methods applied were consistent and indicated that the length of the induction period could not be explained only on the basis of the degree of unsaturation or polar compound levels in fried potatoes before storage. alpha-Tocopherol content also had a significant influence as potatoes fried in HOSO, with 16% polar compounds and only 10 mg/kg alpha-tocopherol at the starting point of storage, were oxidized more rapidly than potatoes fried in SO with a comparatively higher degradation level, 19% polar compounds, and 100 mg/kg alpha-tocopherol.