Estudo químico de uma amostra de própolis verde de Passa Quatro, Minas Gerais, Brasil

The phytochemical investigation of a sample of propolis from Passa Quatro-Minas Gerais State, Brazil, where nine constituents were isolated: a mixture of α- and β-amyrin, lupeol, a mixture of flavonols ramnocitrin and eupalitin, acacetin, 3-prenyl-4-hydroxycinnamic acid, 3,5-diprenyl-4-hydroxycinnamic acid the new compound, the (E)-3-[4-(3-phenylpropanoiloxy)]-3,5-diprenil-cinnamic acid. The structures of the isolated compounds were characterized by 1D- and 2D-NMR experiments, MS and IR spectrometry, and comparison with data described in the literature.

Desenvolvimento de métodos de análise por CLAE-UV para os antimicrobianos tetraciclina, sulfametoxazol e trimetoprima utilizando materiais à base de sílica como sistemas de pré-concentração

This paper evaluates the adsorption capacity of zirconocene-based silica materials in the pre-concentration of antimicrobians (tetracycline, sulfamethoxazole and trimethoprim) in aqueous medium. These materials were prepared by grafting the zirconocene onto silicas pre-treated at different temperatures. The retention capacity of these materials was evaluated by off line SPE and HPLC-UV and the proposed methodology was validated in ultrapure, tap and river water. The recovery for tetracycline was 72% (in the solid phase A) and, for sulfamethoxazole and trimethoprim was 68 and 95% in the commercial C18, respectively. The target antimicrobians were not detected in the Arroio Dilúvio (Porto Alegre - RS).

Alvejamento químico de caulins Brasileiros: efeito do potencial eletroquímico da polpa e do ajuste do pH

Samples of Kaolin from different regions in Brazil were characterized by XRD, SEM and chemical analysis. A chemical bleaching study with pH adjustment was accomplished with the fractions below 37 μm, after classification by screening. The main objective was to evaluate the conditions of chemical bleaching that most increase the brightness of these kaolin's samples. Increases between 2.63 and 2.98% in the brightness (ISO) were observed after the chemical bleaching. We could say that the reduction of Fe3+ to Fe2+ during the chemical bleaching promoted an increase in the brightness, based on the Pourbaix Diagrams.

Variación del grado de avance de reacción en sistemas cerrados en equilibrio químico que modifican la temperatura a volumen constante

In this paper it is presented a thermodynamic analysis that aims to find the mathematical expression of the variation of extent of reaction with the infinitesimal variation in the temperature at constant volume of a chemical equilibrium mixture. The goal of this paper is to establish an alternative approach to avoid both the Le Chatelier's principle and the problems that emerge when trying to apply its qualitative statements. This attempt is based on the laws of thermodynamics.

Acompanhamento químico da vermicompostagem de lodo de esgoto doméstico

This research aims to monitor the humification process of domestic sewage sludge resulted from the vermicomposting, evaluating, also, the possibility of using the final product (vermicompost) in agricultural soils. The monitored chemical variables during the 90 days of vermicomposting were: humidity rate, organic matter content, nitrogen and phosphorus content, pathogenic organisms concentration, total organic carbon, acidity, CEC, C/N ratio, CEC/TOC ratio, and humic and fulvic acids content. The change in these variables during the vermicomposting process showed that this technique is effective for use in the maturation of the residue.

Identificação de alguns constituintes químicos de Indigofera hirsuta Linn. (Fabaceae) por CLAE-IES-EM (TOF) e avaliação da atividade antirradicalar

A rapid analytical approach, suitable to characterize the compounds present in the aqueous and methanol extracts prepared from the aerial parts of Indigofera hirsute, was developed. The method based on high-performance liquid chromatography coupled to mass spectrometry, electrospray positive ionization and detection by time of flight (HPLC-ESI-MS-TOF) identified, tryptophan, uracil, rutin, kaempferol-3-O-β-D-glucopyranoside, gallic acid and methyl gallate. The antiradical activity of this extract was evaluated using DPPH assay, with gallic acid as antiradical pattern. The study revealed the antiradical activity of methyl galatte (EC50 = 5 ± 0.3 µg mL-1) galic acid (EC50 = 5 ± 0.2 µg mL-1) and rutin (EC50 = 21.6 ± 0.6 µg m L-1), isolated from methanol extract (EC50 = 67.7 ± 0.9 µg mL-1), which showed strong antiradical activity.

Validação de método e determinação espectrométrica dos flavonoides das folhas e do vinhoto da cana-de-açúcar e comparação com método CLAE-UV

This paper reports on a modification of the procedures originally described in the French Pharmacopoeia for the UV-visible spectrometric analysis of flavonoids, and proposes a validation of the method and its application in the determination of total flavonoids from sugarcane (Saccharum officinarum) leaves and vinasse. An analysis of precision and accuracy revealed a low relative standard deviation (< 5.0%) and a good recovery percentages (99.79 and 98.34%). A comparison of the spectrometric results against those obtained by high performance liquid chromatography (HPLC-UV) demonstrated complete compatibility between the modified French Pharmacopoeia (spectrometric) and HPLC-UV methods

Quantificação sérica de vitamina C por CLAE-UV e estudo de estabilidade

Vitamin C, an exogenous antioxidant, is essential to human health. In this study, a method was validated to serum vitamin C quantification by HPLC-UV. Its stability with and without the use of tris [2-carboxy-ethyl] phosphine hydrochloride (TCEP), at -20 and -80 °C, in serum and supernatant were also evaluated. Analysis showed r² > 0.99, precision CV% < 15% and % bias < 15%, being linear, precise and accurate. The stability test revealed that using TCEP in serum storage at -20 and -80 °C or in supernatant at -80 °C the vitamin C levels remain stable for 30 and 12 days, respectively.

Desenvolvimento e validação de método analítico por CLAE para a quantificação simultânea de dipropionato de betametasona e fosfato sódico de betametasona em suspensão injetável

A reversed-phase HPLC method was developed and validated to separate and simultaneously quantify the association of betamethasone sodium phosphate (BP) and betamethasone dipropionate (BD) in injectable suspensions. Chromatographic conditions were ternary gradient elution at 1.6 mL/min on a C18 column with 254 nm. The linearity of the method was established in the range 120 to 280 mg/mL BD, and 48 to 112 mg/mL BP. The RSD of intermediate precision of the method was <1% and recoveries were 99-101% for both drugs. The method proved selective, linear, precise, accurate and robust for quantifying BP and BD in commercial injectable suspensions.

Desenvolvimento e validação de método analítico para a determinação de sulfassalazina em suspensão oral: comparação do método espectrofotométrico e de cromatografia líquida de alta eficiência (CLAE)

Sulfasalazine is a prodrug used in the treatment of the Chron's disease and rheumatoid arthritis. Two analytical methods for analysis of sulfasalazine in oral suspension were validated using Spectrophotometric and HPLC. There is not any pharmacopoeic method to assay sulfasalazine in oral suspension. The methods are insurance and fast execution for the quality control. Both, suspension and tablets 500 mg (Azulfin®) had been analyzed by methods using UV/VIS and HPLC and the results were satisfactory.

Estudo químico de Sinningia allagophylla guiado por testes de atividade antiproliferativa

Activity guided fractionation of Sinningia allagophylla (Mart.) Wiehler ethanolic extract yielded a new benzochromene 8-methoxylapachenol, besides seven known compounds: lapachenol, sitosteryl oleate, sitosteryl linoleate, stigmasteryl oleate, stigmasteryl linoleate, dunniol and tectoquinone. Extract, fractions, and compounds lapachenol, 8-methoxylapachenol, and dunniol were tested in vitro against human cancer cell lines U251 (glioma, CNS), MCF-7 (breast), NCI-ADR/RES (drug-resistant ovarian), 786-0 (kidney), NCI-H460 (lung, no small cells), PC-3 (prostate), OVCAR-3 (ovarian), HT-29 (colon), K562 (leukemia) and against VERO, a normal cell line. The most active compound was dunniol, which inhibited the growth of U251, MCF-7, NCI-ADR/RES, OVCAR-3 and K562 cell lines.

Desenvolvimento e validação de um método analítico por CLAE para quantificação de ácido ursólico em dispersões sólidas

Ursolic acid is a natural molecule that presents several pharmacological properties. In this work, an analytical method by RP-HPLC has been developed and validated for quantification of this drug in the solid dispersions, using PEG 6000 and Poloxamer 407 as polymers. The method was specific, linear in the range of 1.0-50.0 µg mL-1 (r<0.99), precise (CV < 5% for both inter- and intra-assays), accurate (maximum deviation of ± 13%), and robust to the parameters evaluated. This method has proved to be simple and useful for ursolic acid determination in solid dispersions, enabling its determination in pharmaceutical dosage form.

Bioactive triterpenes and phenolics of leaves of Eugenia brasiliensis

A chemical investigation of Eugenia brasiliensis Lam. (Myrtaceae) leaves led to the isolation of α-amyrin and β-amyrin (in a mixture), betulin, 29-hydroxy-oleanolic acid, quercetin, catechin and gallocatechin. Herein, the identification of 29-hydroxy-oleanolic acid is reported for the first time in the Myrtaceae family. Moreover, in this study, the extract, fractions and six of the seven compounds were monitored for toxicity toward Artemia salina, antibacterial and acetylcholinesterase inhibitory activity. The crude ethanol extract of the leaves and fractions were found be active on A. salina toxicity bioassay.

Comparação do perfil químico entre cachaças de um mesmo vinho destiladas em alambiques e em colunas

Six wines were distilled in two different distillation apparatus (alembic and column) producing 24 distillates (6 for each alembic fraction - head, heart and tail; 6 column distillates). The chemical composition of distillates from the same wine was determined using chromatographic techniques. Analytical data were subjected to Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) allowing discrimination of four clusters according to chemical profiles. Both distillation processes influenced the sugarcane spirits chemical quality since two types of distillates with different quantitative chemical profiles were produced after the elimination of fermentation step influence.

Os nanomateriais e a descoberta de novos mundos na bancada do químico

In recent years there has been great progress in the field of nanotechnology largely driven by research into nanomaterials. Chemistry appears in this context for its relevant role in the synthesis and surface modification of nanomaterials. This review article discusses fundamental concepts related to the synthesis and properties of inorganic nanoparticles with diverse properties. Aspects related to unique size dependent optical and magnetic properties are discussed and the chemistry involved in the preparation of nanomaterials reviewed. Fundamental aspects of the chemical modification of nanoparticles envisaging potential applications for these materials are also addressed.