Bioactive flavone dimers from Ouratea multiflora (Ochnaceae)

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

Development, optimization and validation of gas chromatographic fingerprinting of Brazilian commercial gasoline for quality control

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Chemical study of leaves of Chrysophyllum marginatum (Hook. & Arn.) Radlk (Sapotaceae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Aristolactams and further constituents from Aristolochia chamissonis

Isolou-se do extrato etanólico de galhos de Aristolochia chamissonis espatulenol, sitosterol, sitosterol-beta-D-glicosídeo, colavelool, 13-epi-2-oxo-colavelool, trans-N-p-coumaroiltiramina, alantoína, ácido aristolóquico I e aristolactama AII. As estruturas da aristolactama AII e da piperolactama A são revisadas com base em análises espectrométricas e derivatizações químicas.

Constituintes químicos isolados dos caules de Michelia champaca L. (Magnoliaceae)

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

Tropical biodiversity: has it been a potential source of secondary metabolites useful for medicinal chemistry?

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

Inhibitory activity of compounds isolated from Polymnia sonchifolia on aflatoxin production by Aspergillus flavus

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

Genetic markers between Biomphalaria glabrata snails susceptible and resistant to Schistosoma mansoni infection

The analysis of the genetic variability related to susceptibility to Schistosoma mansoni infection in the vector of the genus Biomphalaria is important in terms of a better understanding of the epidemiology of schistosomiasis itself, the possible pathological implications of this interaction in vertebrate hosts, and the formulation of new strategies and approaches for disease control. In the present study, the genetic variability of B. glabrata strains found to be resistant or susceptible to S. mansoni infection was investigated using DNA amplification by random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR). The amplification products were analyzed on 8% polyacrylamide gel and stained with silver. We selected 10 primers, since they have previously been useful to detect polymorphism among B. glabrata and/or B. tenagophila. The results showed polymorphisms with 5 primers. Polymorphic bands observed only in the susceptible strain. The RAPD-PCR methodology represents an adequate approach for the analysis of genetic polymorphisms. The understanding of the genetic polymorphisms associated to resistance may contribute to the future identification of genomic sequences related to the resistance/susceptibility of Biomphalaria to the larval forms of S. mansoni and to the development of new strategies for the control of schistosomiasis.

Attitude stabilization of a rigid spacecraft in the geomagnetic field

An analytical method is proposed to study the attitude stability of a triaxial spacecraft moving in a circular Keplerian orbit in the geomagnetic field. The method is developed based on the electrodynamics effect of the influence of the Lorentz force acting on the charged spacecraft's surface. We assume that the rigid spacecraft is equipped with an electrostatic charged protective shield, having an intrinsic magnetic moment. The main elements of this shield are an electrostatic charged cylindrical screen surrounding the protected volume of the spacecraft. The rotational motion of the spacecraft about its centre of mass due to torques from gravitational force, as well Lorentz and magnetic forces is investigated. The equilibrium positions of the spacecraft in the orbital coordinate system are obtained. The necessary and sufficient conditions for the stability of the spacecraft's equilibrium positions are constructed using Lyapunov's direct method. The numerical results have shown that the Lorentz force has a significant influence on the stability of the equilibrium positions, which can affect the attitude stabilization of the spacecraft. (C) 2007 COSPAR. Published by Elsevier Ltd. All rights reserved.

Benzoate ion determination in beverages by using a potentiometric sensor immobilized in a graphite matrix

The characteristics, performance, and application of an electrode, namely. Pt\Hg\Hg-2(Bzt)(2)\graphite, where Bzt stands for benzoate ion. are described. This electrode responds to Bzt with sensitivity of 57.7 +/- 1.0 mV/decade over the range 5 x 10(-4)-1 x 10(-1) mol l(-1) at pH 6.0-8.0 with a detection limit of 1.6 x 10(-4) mol l(-1). The electrode shows easy construction, fast response rime (between 10-30 s), low-cost, acid excellent response stability (lifetime > 6 months, in continuous use), the proposed sensor displayed good selectivity for benzoate in the presence of several carboxylate and inorganic anions. It was used to determine benzoate in various beverages by means of the standard additions method. The results obtained by using this electrode compared very favorably with those given by the official AOAC spectrophotometric method and by a HPLC procedure as well. (C) 2001 Elsevier B.V. B.V. All rights reserved.

p-Aminobenzoate ion determination in pharmaceutical formulations by using a potentiometric sensor immobilized in a graphite matrix

The characteristics, performance, and application of an electrode, namely, Pt\Hg\Hg-2(PABzt)(2)\ graphite, where PABzt stands for p-aminobenzoate ion, are described. This electrode responds to PABzt with sensivity of (58.1 +/- 1.0) mV per decade over the range 1.0 x 10(-4) to 1.0 x 10(-1) mol l(-1) at pH 6.5-8.0 and a detection limit of 3.2 x 10(-5) mol l(-1). The electrode shows easy construction, fast response time (within 10-30 s), low-cost, and excellent response stability (lifetime greater than 6 months, in continuous use). The proposed sensor displayed good selectivity for p-aminobenzoate in the presence of several substances, especially, concerning carboxylate and inorganic anions. It was used to determine p-aminobenzoate in pharmaceutical formulations by means of the standard additions method. The results obtained by using this electrode compared very favorably with those given by an HPLC procedure. (C) 2004 Elsevier B.V. All rights reserved.

Iridoid and seco-iridoid glucosides from Chioccoca alba (Rubiaceae)

Phytochemical investigation of Chioccoca alba afforded three new iridoids, alboside I, alboside II and alboside III, and a new seco-iridoid alboside V. Alboside IV showed moderate activity towards the DNA repair-deficient mutant RS321 of Saccharomyces cerevisiae. The structural elucidation of the new compounds was performed by ES-MS and by 1D and 2D NMR spectroscopic methods. (C) 1999 Elsevier B.V. Ltd. All rights reserved.

Composition and antifungal activity of essential oils from Piper aduncum, Piper arboreum and Piper tuberculatum

The composition of essential oils from leaves, stems and fruits of Piper aduncum, P arboreum and P. tuberculatum was examined by means of GC-MS and alltifungal assay. There was a predominance of monoterpenes in P aduncum and P tuberculatum and of sesquiterpenes in P arboreum. P aduncum showed the richest essential oil composition, including linalool. The essential oils from fruits of P. aduncum and R tuberculatum showed the highest antifungal activity with the MIC of 10 mu g as determined against Cladosporium cladosponoides and C. sphaerospermum, respectively. This is the first report of the composition of essential oils from P. tuberculatum.

Tetrahydroisoquinoline alkaloids and 2-deoxyribonolactones from Aristolochia arcuata

2-Deoxyribonolactones and four tetrahydroisoquinoline alkaloids were isolated from the acetone extract of the leaves of Aristolochia arcuata Mast., together with pinitol, sequoyitol, glycerol, fructose, sucrose, eupomatenoid-7, salsolinol, and 6,7-dihydroxyl,1-dimethyl-1,2,3,4-tetrahydroisoquinoline. Their structures were determined on the basis of spectroscopic methods, mainly using H-1, C-13, N-15, and P-31 NMR. (C) 2003 Elsevier B.V. Ltd. All rights reserved.