ESTABILIDADE TERMICA DO PARACETAMOL EM SOLUCAO: CROMATOGRAFIA EM CAMADA DELGADA (CCD) - ESPECTROFOTOMETRIA ULTRAVIOLETA

The interference practised by the products in degradation of paracetemol when there is the application of spectrophotometry UV is the main obstruction to the execution of studies of thermic stability. The application of chromatography in slender layer to the isolation of paracetamol, besides being the excessively hard to apply was satisfactory to the desired proposal. The type and extension of degradation suffered by paracetamol in solution suggest the convenient inclusion, in the formulations, of one system antioxidant. This practice makes possible the blockage of the oxidation of p-aminophenol, produced by the hydrolytic degradation of paracetamol; this fact propitiated the diminution of the number of products of degradation in the medicine, making the use more secure. On the other hand, considering especially the methodological necessities of the present work, the presence of one antioxidant system facilitated the separation of paracetamol through the Thin Layer Chromatography and consequently optimized its quantification by Spectrophotometry UV during the study of thermic stability. The formulation proposed revealed excellent stability.

Thermal decomposition of acetylsalicylic acid (aspirin)

The thermal decomposition of aspirin in air and dry air flux was investigated. Thermogravimetry-derivative thermogravimetry (TG-DTG), differential scanning calorimetry (DSC), nuclear magnetic resonance (NMR), infrared absorption spectra and thin layer chromatography have been used to study the thermal decomposition of this compound. The results permit the identification of some compounds revealed in the first step of the TG-DTA curves, and also suggest the thermal decomposition mechanism.

Isolation of ergosterol peroxide and its reversion to ergosterol in the pathogenic fungus Sporothrix schenckii

Ergosterol peroxide, a presumed product of the H2O2-dependent enzymatic oxidation of ergosterol, has been isolated from yeast from yeast forms of the pathogenic fungus Sporothrix schenckii. The substance, which may have a role in fungal virulence, has been characterized mainly using spectroscopic methods (1H and 13C nuclear magnetic resonance and high resolution mass spectra). The purified compound showed a molecular formula of C28H44O3, displaying characteristic features of epidioxy sterols and was reverted to ergosterol when submitted to S. schenckii enzymatic extract.

Incidence of patulin in fruits and fruit juices marketed in Campinas, Brazil

One hundred and eleven samples of processed fruit juices (apple, grape, pineapple, papaya, guava, banana and mango) and 38 samples of sound fruits (apple, papaya, mango, pear and peach) produced and marketed in Brazil, were analysed for patulin by HPLC. Only one out of 30 samples of apple juice was found positive at 17 μg/l. Patulin was not detected in the other foodstuffs. It was found in 14 samples of spoiled fruit samples of apple (150-267 μg/kg), pear (134-245 μg/kg) and peach (92-174 μg/kg). Confirmation of the identity of patulin was based on the UV spectrum obtained by the HPLC diode array detector, compared with that of standard patulin, TLC developed by several solvent systems and sprayed with 3-methyl-2-benzothiazolinone hydrazone, and by acetylation with acetic anhydride.

A new cytotoxic naphthopyrone dimer from Paepalanthus bromelioides

A new naphthopyrone dimer was isolated from the capitula of Paepalanthus bromelioides by chromatographic procedures. Its structure was deduced from spectrometric data. On colorimetric assay for cytotoxicity the new dimer showed IC50 of 55.9 μM. (C) 2000 Elsevier Science B.V.

Cromatografia em contra-corrente de gotejamento na separação de substâncias fenólicas de Neuropogon aurantiaco-ater

This work reports the separation of phenolic compounds present in the metabolic extract of the lichen Neuropogon aurantiaco-ater (Usniaceae). The crude extract was fractionated by droplet counter-current chromatography using a solvent mixture of high polarity (chloroform:methanol:water at 43:37:20, in ascending mode). The separation resulted in the isolation of usnic and protocetratic acid, which were identified by TLC, HPLC, and NMR tests.

Ativação de macrófagos por produtos naturais obtidos da Achillea millefolium L. (Asteraceae)

Plants are a valuable source of natural products for the maintenance of human health. The purpose of this paper was the study of immunologic activity of yarrow (Achillea millefolium L.), a largely used plant in popular medicine that has many different properties such as: antiinflammatory, astringent, antiseptic and antispasmodic. Macrophages stimulation was evaluated by the determination of H2O2, NO and TNF-α in supernatants of peritoneal macrophages cultures of mice in the presence of the yarrow leaves extract. The thin layer chromatography of extract was also analyzed, showing rutin. All concentrations showed a moderate release of H2O2 and the concentrations of 6, 8 and 10mg/mL had a higher release of NO. The TNF-a was produced in all concentrations, but the best result was obtained at 4mg/mL. Analyzing the results, it is suggested that the yarrow ethanolic extract can modulate the macrophages activation.

Adsorption of silanes bearing nitrogenated Lewis bases on SiO 2/Si (100) model surfaces

The present paper describes the one-pot procedure for the formation of self-assembled thin films of two silanes on the model oxidized silicon wafer, SiO2/Si. SiO2/Si is a model system for other surfaces, such as glass, quartz, aerosol, and silica gel. MALDI-TOF MS with and without a matrix, XPS, and AFM have confirmed the formation of self-assembled thin films of both 3-imidazolylpropyltrimethoxysilane (3-IPTS) and 4-(N- propyltriethoxysilane-imino)pyridine (4-PTSIP) on the SiO2/Si surface after 30 min. Longer adsorption times lead to the deposition of nonreacted 3-IPTS precursors and the formation of agglomerates on the 3-IPTS monolayer. The formation of 4-PTSIP self-assembled layers on SiO2/Si is also demonstrated. The present results for the flat SiO2/Si surface can lead to a better understanding of the formation of a stationary phase for affinity chromatography as well as transition-metal-supported catalysts on silica and their relationship with surface roughness and ordering. The 3-IPTS and 4-PTSIP modified SiO2/Si wafers can also be envisaged as possible built-on-silicon thin-layer chromatography (TLC) extraction devices for metal determination or N-heterocycle analytes, such as histidine and histamine, with on-spot MALDI-TOF MS detection. © 2005 Elsevier Inc. All rights reserved.

Bioprospecção de atividade antioxidante e antimicrobiana da casca de Stryphnodendron adstringens (Mart.) Coville (Leguminosae-Mimosoidae)

The aim of this work was to evaluate the class of secondary metabolites responsible for the antioxidant and antimicrobial activities of bark extracts of Stryphnodendron adstringens (Mart.) Coville (Leguminosae-Mimosoidae), a plant widely used in folk medicine in Brazil. Extracts of the bark were prepared with 50% ethanol, 70% ethanol, acetone:water (7:3, v/v) and chloroform. Antioxidant activity was prospected by spraying thin-layer chromatographs of the extracts with 2,2-diphenyl-1-picryl-hydrazyl (DPPH) and measuring the DPPH radical scavenging capacity by spectrophotometry. Antibacterial activity was revealed by the agar diffusion method and bioautography. TLC spots assigned to tannins in the polar extracts showed antioxidant activity by DPPH radical scavenging and the chloroform extract showed the least scavenging activity. Antimicrobial activity was indicated by the bacterial growth inhibition haloes around polar extracts and bioautography showed activity in the TLC spots assigned to tannins. It was concluded that polar extracts of the bark of S. adstringens possessed antioxidant and antimicrobial activities which were due to secondary metabolite derived from the tannin class, which are the main constituent of these bark extracts, according to the literature.

Determinação de fármacos diuréticos em associação por cromatografia em camada delgada e espectrofotometria

A rapid, sensitive and reliable thin-layer chromatography/spectrophotometry screening procedure was developed for quantitative determination of diuretics associated in pharmaceutical dosage forms. The chromatographic method employed microcrystalline cellulose and butanol : acetic acid : water (4:1:1) or amilic alcohol : ammonium hydroxide 25% (9:1) as mobile phases and detection by U.V. light. The drugs were extracted using a simple procedure and were quantified by U.V. spectrophotometry. Results varied from 97.5 to 102.5% and are similar to those obtained by conventional methods. This method of quantification of diuretics is promising for quality control of drugs.

Identificação de diterpenos clerodânicos em diferentes órgãos de Casearia sylvestris Swartz

Casearia sylvestris Swartz (Salicaceae) is a tree or shrub distributed widely in Brazil, where it is used in popular medicine. Several bioactive clerodane diterpenes typical of Casearia have been isolated from this species (e.g. casearins and casearvestrins). The main objective of this study was to identify clerodane diterpenes in various organs of C. sylvestris, using chromatographic and spectroscopic analytical techniques. The extracts of the different plant parts were analyzed by thin layer chromatography, high performance liquid chromatography with diode array detector and 1H nuclear magnetic resonance. In the chromatographic analysis, clerodane diterpenes isolated from C. sylvestris were used as standards, including rel-19Sacetóxi-18R- butanoilóxi-18,19- epóxi -6S -hidróxi -2R-(2-metilbutanoilóxi) -5S, 8R, 9R, 10S -cleroda-3,13(16),14-triene, isolated for the first time from the stems. Phytochemical profiles of the organs were produced, which indicated the presence of clerodane diterpenes in all parts of the plant, notably in the leaves. The results also suggest that the main clerodane diterpenes in the stems, flowers and roots had conjugated double-bond patterns that differed from those found in the leaves.

rastreamento histoquímico, fitoquímico e biológico de folhas de Plinia cauliflora (DC.) Kausel (Myrtaceae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Recent applications of analytical techniques for quantitative pharmaceutical analysis: A review

The intension of this paper was to review and discuss some of the current quantitative analytical procedures which are used for quality control of pharmaceutical products. The selected papers were organized according to the analytical technique employed. Several techniques like ultraviolet/visible spectrophotometry, fluorimetry, titrimetry, electroanalytical techniques, chromatographic methods (thin-layer chromatography, gas chromatography and high-performance liquid chromatography), capillary electrophoresis and vibrational spectroscopies are the main techniques that have been used for the quantitative analysis of pharmaceutical compounds. In conclusion, although simple techniques such as UV/VIS spectrophotometry and TLC are still extensively employed, HPLC is the most popular instrumental technique used for the analysis of pharmaceuticals. Besides, a review of recent works in the area of pharmaceutical analysis showed a trend in the application of techniques increasingly rapid such as ultra performance liquid chromatography and the use of sensitive and specific detectors as mass spectrometers.

Structural characterization of a new dextran with a low degree of branching produced by Leuconostoc mesenteroides FT045B dextransucrase

This paper offers the physical and chemical characterization of a new dextran produced by Leuconostoc mesenteroides FT045B. The chemical structure was determined by Fourier Transform Infrared spectroscopy and 1H Nuclear Magnetic Resonance spectroscopy. The dextran was hydrolyzed by endodextranase; the products were analyzed using thin layer chromatography and compared with those of commercial B-512F dextran. The number-average molecular weight and degree of polymerization of the FT045B dextran were determined by the measurement of the reducing value using the copper bicinchoninate method and the measurement of total carbohydrate using the phenol-sulfuric acid method. The data revealed that the structure of the dextran synthesized by FT045B dextran sucrase is composed of d-glucose residues, containing 97.9% α-(1,6) linkages in the main chains and 2.1% α-(1,3) branch linkages compared with the commercial B-512F dextran, which has 95% α-(1,6) linkages in the main chains and 5% α-(1,3) branch linkages. © 2012 Elsevier Ltd. All rights reserved.