Comparative study of the cathodic cleavage of N-tosyl- and N-nosyl-protected amino acids

The electrochemical behaviour of alanine and phenylalanine protected by the toluenesulphonyl (tosyl) and nitrobenzesulphonyl (nosyl) groups was examined in dimethyl formamide. The N-tosyl-protected amino acids are reduced in one cathodic step (-2.4 V/SCE) leading to cleavage of the SN bond after a two-electron transfer process. The N-nosyl-protected amino acids are reduced in three cathodic steps. Cyclic voltammetry and controlled potential electrolysis of N-nosyl amino acids have been used to probe the mechanism of these reductions in an aprotic medium and lead to cleavage of the SN bond in good yields ( > 60%) at -1.10 V/SCE. The comparative study of these compounds is used to comment on the applicability of the electrochemical method of removing protecting groups from amino acids. © 1993.

l-amino acid oxidase from Bothrops marajoensis causes nephrotoxicity in isolated perfused kidney and cytotoxicity in MDCK renal cells

Renal alterations caused by Bothrops venom and its compounds are studied to understand these effects and provide the best treatment. Previously, we studied the renal effect of the whole venom of Bothrops marajoensis and its phospholipase A2 (PLA2), but these effects could not to be attributed to PLA2. To continue the study, we report in this short communication the effects of l-amino acid oxidase from B. marajoensis venom (LAAOBm) on renal function parameter alterations observed in the same model of isolated perfused kidney, as well as the cytotoxic effect on renal cells. LAAOBm caused a decrease in PP, RVR, UF, GFR, %TNa(+) and %TCl(-), very similar to the effects of whole venom using the same model. We also demonstrated its cytotoxicity in MDCK cells with IC50 of 2.5 μg/mL and late apoptotic involvement demonstrated by flow cytometry assays. In conclusion, we suggested that LAAOBm is a nephrotoxic compound of B. marajoensis venom.

Silsesquioxane organofunctionalized with 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole: preparation and subsequent reaction with silver and potassium hexacyanoferrate(III) for detection of l-cysteine

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

On partial derivative-Neumann's problem in generalized functions framework

In this paper, we show that the equation delta u/delta (z) over bar + Gu = f, where the elements involved are in generalized functions context, has a local solution in the generalized functions context.

Development and validation of first derivative spectrophotometric method for quantification of darunavir in tablets

Aims: Darunavir is widely used in HIV/AIDS therapy. It is a HIV protease inhibitor that has excellent efficacy against the virus. The aim of this study is to develop and validate an analytical method fast and free of interferences for determination of darunavir ethanolate as raw material and tablet dosage form. Methodology: As the formulation excipients show high interference in darunavir determination by a direct UV absorption measurement a derivative spectrophotometry was applied. A selective, easy and fast method was achieved employing simple and cheap instrumentation by using first-order derivative spectrophotometry. Results: The first-derivation of spectrum of the drug measured between 200 and 400 nm allowed identification of the analyte and showed absence of placebo interference. The assay was based on the absorbance at 276nm. The linear concentration range was established from 11 to 21 μg/mL. The intra-day and inter-day precision expressed as RSD was 0.06% and 3.75% respectively with mean recovery of 99.84%. Conclusion: The proposed analytical method is able to quantify darunavir as raw material and tablets and can be used routinely by any laboratory applying a spectrophotometer with a derivative accessory. The great difference of the method proposed here is that it proves to be free of placebo interferences as well as simple, fast and low cost.

Development and validation of dissolution test for fluconazole capsules by HPLC and derivative UV spectrophotometry

The purpose of this study is to develop and validate a dissolution test for fluconazole, an antifungal used for the treatment of superficial, cutaneous, and cutaneomucous infections caused by Candida species, in capsules dosage form. Techniques by HPLC and UV first derivative spectrophotometry (UV-FDS) were selected for quantitative evaluation. In the development of release profile, several conditions were evaluated. Dissolution test parameters were considered appropriate when a most discriminative release profile for fluconazole capsules was yielded. Dissolution test conditions for fluconazole capsules were 900 mL of HCl 0.1 M, 37 ± 0.5 °C using baskets with 50 rpm for 30 min of test. The developed HPLC and UV-FDS methods for the antifungal evaluation were selective and met requirements for an appropriate and validated method, according to ICH and USP requirements. Both methods can be useful in the registration process of new drugs or their renewal. For routine analysis application cost, simplicity, equipment, solvents, speed, and application to large or small workloads should be observed.

A first-derivative spectrophotometric method for the determination of ciprofloxacin hydrochloride in ophthalmic solution

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Oxidation of amino acids by chlorpromazine cation radical and co-catalysis by chlorpromazine

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

Sílica mesoporosa como suporte sólido para o ancoramento da molécula 4-amino-3-hidrazino-5-mercapto-1,2,4-triazole e aplicação na adsorção de Cu(II), Cd(II), Ni(II), Pb(II) e Co(II) em amostras aquosas

Pós-graduação em Química - IQ

Adsorção de metais em solução aquosa pelos processos de batelada e coluna de leito fixo utilizando silsesquioxano funcionalizado com 5-amino-1,3,4-tiadiazol-2-tiol

Pós-graduação em Ciência dos Materiais - FEIS

Isolamento e caracterização de ciclotídeos da espécie Noisettia orchidiflora (Rudge) Ging.

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estudo peptídico e determinação do perfil de metabólitos de venenos de escorpiões da família buthidae: Tityus serrulatus, Tityus bahiensis e Tityus obscurus

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Comparison Between Micro- and Macrosurgical Techniques for the Treatment of Localized Gingival Recessions Using Coronally Positioned Flaps and Enamel Matrix Derivative

Background: The aim of this study is to compare the macro- and microsurgery techniques for root coverage using a coronally positioned flap (CPF) associated with enamel matrix derivative (EMD). Methods: Thirty patients were selected for the treatment of localized gingival recessions (GRs) using CPF associated to EMD. Fifteen patients were randomly assigned to the test group (TG), and 15 patients were randomly assigned to the control group (CG). The microsurgical approach was performed in the TG, and the conventional macrosurgical technique was performed in the CG. The clinical parameters evaluated before surgery and after 6 months were GR, probing depth, relative clinical attachment level, width of keratinized tissue (WKT), and thickness of keratinized tissue (TKT). The discomfort evaluation was performed 1 week postoperative. Results: There were no statistically significant differences between groups for all parameters at baseline. At 6 months, there was no statistically significant difference between the techniques in achieving root coverage. The percentage of root coverage was 92% and 83% for TG and CG, respectively. After 6 months, there was a statistically significant increase of WKT and TKT in TG only. Both procedures were well tolerated by all patients. Conclusions: The macro- and microsurgery techniques provided a statistically significant reduction in GR height. After 6 months, there was no statistically significant difference between the techniques regarding root coverage, and the microsurgical technique demonstrated a statistically significant increase in WKT and TKT. J Periodontol 2010;81:1572-1579.

Percolated non-Newtonian flow for silicone obtained from exfoliated bioinorganic layered double hydroxide intercalated with amino acid

A simple and scalable procedure was used to obtain thin, stable, homogeneous, and easy-to-handle films composed of silicone derived from dimethicones containing dispersed hydrotalcite-type materials previously organo-modified with amino acids. The absence of the typical X-ray pattern of the bioinorganic LDH filler suggested an exfoliation process that was further indirectly evidenced by a drastic change in the rheological behavior, which turned from a quasi-Newtonian behavior for the silicone free of LDH filler to an extensive developed gel-like structure for the nanocomposite derivatives. Visualized by the shear-thinning exponent of the complex viscosity in the low-frequency range, the percolation threshold was evident for filler loading as low as <5 w/W%, suggesting the presence of a largely developed interface between the filler and the polymer. The increase of more than one order of magnitude in viscosity was explained by the rather strong attrition phenomenon between the tethered amino acid anions and the silicone chains. UVB radiation absorption profiles make such bioinorganic polymer nanocomposites potentially applicable in skin protection. Thermo-gravimetric analysis revealed significant improvement in the thermal stability, especially in the final step of the polymer combustion, thus underlining the role of the hybrid material as a thermal retardant agent. (C) 2011 Elsevier B.V. All rights reserved.

Physiological effects of glyphosate over amino acid profile in conventional and transgenic soybean (Glycine max)

This paper compares the responses of conventional and transgenic soybean to glyphosate application in terms of the contents of 17 detectable soluble amino acids in leaves, analyzed by HPLC and fluorescence detection. Glutamate, histidine, asparagine, arginine + alanine, glycine + threonine and isoleucine increased in conventional soybean leaves when compared to transgenic soybean leaves, whereas for other amino acids, no significant differences were recorded. Univariate analysis allowed us to make an approximate differentiation between conventional and transgenic lines, observing the changes of some variables by glyphosate application. In addition, by means of the multivariate analysis, using principal components analysis (PCA), cluster analysis (CA) and linear discriminant analysis (LDA) it was possible to identify and discriminate different groups based on the soybean genetic origin. (C) 2011 Elsevier Inc. All rights reserved.