Eficiência simbiótica de isolados de rizóbio noduladores de feijão-fava (Phaseolus lunatus L.)

Em leguminosas tropicais, a cuidadosa seleção de estirpes de rizóbio, entre outros fatores, é fundamental para a eficiência da fixação biológica de N2 (FBN). Essa seleção deve ser feita para as leguminosas de interesse social e econômico, entre elas o feijão-fava (Phaseolus lunatus L.). O objetivo deste trabalho foi avaliar a eficiência simbiótica de rizóbios nativos de duas regiões do Piauí produtoras de feijão-fava. Foram avaliados 17 isolados e duas estirpes de referência (CIAT 899 e NGR 234), em casa de vegetação, utilizando-se vasos de Leonard autoclavados, no delineamento experimental inteiramente ao acaso, com três repetições. O genótipo de feijão-fava utilizado foi o UFPI-468. A inoculação foi feita por ocasião do plantio. A coleta foi realizada aos 34 dias após o plantio, sendo avaliadas as seguintes características: matéria seca da parte aérea (MSPA), da raiz (MSR) e dos nódulos (MSN); relação MSPA/MSR; N acumulado (Nac) na MSPA e a eficiência da fixação de N2. Foi observada diferença significativa entre os isolados em todas as características, exceto em MSR. Em geral, os isolados ISO-18, ISO-23, ISO-24, ISO-25, ISO-30, ISO-32, ISO-35, ISO-36, ISO-43 e ISO-45 apresentaram os melhores índices de MSPA, MSR, MSPA/MSR, Nac e eficiência da fixação de N2, em relação aos isolados ISO-2, ISO-9, ISO-16, ISO-40 e testemunha absoluta. As características avaliadas foram suficientes para discriminar e selecionar isolados eficientes na nodulação em feijão-fava, contribuindo para a efetividade da FBN. Os melhores isolados apresentaram bom desempenho no fornecimento de N às plantas, podendo ser recomendados para testes de eficiência agronômica.

Antioxidant compoundsand total antioxidant activity in fruits of acerola from cv. Flor Branca, Florida Sweet and BRS 366

Information on antioxidant properties at different ontological stages may help producers and food technologists to identify which cultivar and/or maturity stage are most adequate for their need, therefore this work aimed to study the changes in the antioxidant metabolism during acerola development. Fruit from cv. Flor Branca, BRS366 and Florida Sweet were harvested at different stages: immature green colored (I), physiologically mature with green color and maximum size (II), breaker (III) and full red ripe (IV). After harvest, fruits were selected, divided into four replications with 500 g each and evaluated regarding their titratable acidity, pH, soluble solids, total soluble sugar, vitamin C, polyphenol, anthocyanin, yellow flavonoid, total antioxidant activity and antioxidant enzyme activity. Anthocyanin and flavonoid were determined through LC-DAD-ESI/MS and all analysis followed a completely randomized factorial 3 x 4 design. Fruits of 'Florida Sweet' presented significantly higher soluble solids (9.46ºBrix). Vitamin C content decreased during ripening, but ripe 'BRS 366' fruits showed the greatest values (1363 mg.100 g-1) and highest TAA with 42.36 µM TEAC.g-1FW. Cyanidin 3-rhamnoside (520.76 mg.100 g-1 DM) and quercetin 3-rhamnoside (33.72 mg.100 g-1 DM) were the most abundant anthocyanin and yellow flavonoids found mainly in 'Flor Branca' fruit of acerola, whose antioxidant enzymes activities were also higher. Ripe 'Florida Sweet' fruit presents a great potential for fresh consumption, meanwhile physiologically mature 'BRS 366' fruit seems the best option for the bioactive compounds processing industry. As 'Flor Branca' fruit of acerola kept the highest activity levels, it could be an indicative of greater potential for postharvest conservation.

Análise quiral por espectrometria de massas através da utilização do método cinético

Novel and quantitative mass spectrometry methods for rapid and accurate enantiomeric excess determination are presented. These methodologies use electrospray ionization (ESI) and mass spectrometry (MS) to detect and analyze, via collision-induced dissociation (CID), mass-selected transition metal complexes that promote enantio especific interactions. The data from CID are conveniently treated by the kinetic method, a sensitive linear free energy method of treating mass spectrometric results. Four different variations of this methodology are described: single ratio method (S R), quotient ratio method (Q R), fixed ligand method (S Rfixed), and quotient ratio method with fixed ligand (Q Rfixed). These individual methods are compared and their main features discussed in detail.

Determinação de resíduos de cloranfenicol em amostras de leite e mel industrializados utilizando a técnica de espectrometria de massas em "tandem" (CLAE-EM/EM)

The present work shows a method for the determination of chloramphenicol (CAP) antibiotic in milk, powder milk and honey. The solid phase extraction and liquid-liquid extraction were applied as a clean-up and pre-concentration strategies followed by LC-ESI/MS/MS analysis. The recovery was studied for different fortification levels from 0.05 to 1.00 µg L-1 in milk, showing values between 91 101% and RSD bellow 8.0%, while honey was spiked with a concentration of 0.20 µg kg-1 yelding a mean recovery of 83% and RSD of 6.5%. The quantification transition 321>152 showed a LOD of 0.52 ng kg-1 and LOQ of 1.85 ng kg-1.

Aplicação da química quântica computacional no estudo de processos químicos envolvidos em espectrometria de massas

The field of application of mass spectrometry (MS) has increased considerably due to the development of ionization techniques. Other factors that have stimulated the use of MS are the tandem mass spectrometry (MS/MS) and sequential mass spectrometry (MSn) techniques. However, the interpretation of the MS/MS and MSn data may lead to speculative conclusions. Thus, various quantum chemical methods have been applied for obtaining high quality thermochemical data in gas phase. In this review, we show some applications of computational quantum chemistry to understand the formation and fragmentation of gaseous ions of organic compounds in a MS analysis.

Composição química e atividade biológica de extrato oleoso de própolis: uma alternativa ao extrato etanólico

Propolis is mostly used as hydroalcoholic extract. Recently there has been a growing number of patents dealing with new solvents for preparing propolis extracts. This study aimed to prepare edible oil propolis extracts and compare their chemical composition and biological activity with ethanolic propolis extracts. ESI-MS and spectrophotometric methods were used for qualitative and quantitative analyses, respectively. Antibacterial activity was evaluated by diffusion in agar. Cytotoxicity was tested by MTT assay using tumor cell lines. The oil is able to extract bioactive compounds from propolis. Further studies are needed to improve extraction efficiency and to characterize the active components.

Nióbia sintética modificada como catalisador na oxidação de corante orgânico: utilização de H2O2 e O2 atmosférico como oxidantes

In this work synthetic niobia was used to promote the oxidation of methylene blue dye in aqueous medium. The niobia was characterized by N2 adsorption/desorption, XRD and TG measurements. The presence of reactive species on the niobia surface strongly increased the oxidation rate of the methylene blue dye. The reaction mechanism was studied by ESI-MS suggesting that the oxidation of the organic dye involve oxidizing species generated mainly after previous treatment with H2O2. It can be observed that the catalyst is a good material in the activation of gas (atmospheric oxygen) or liquid (hydrogen peroxide) oxidant agent with a total discoloration of the dye solution after only 1 h of reaction.

Síntese e caracterização de nanopartículas de óxido de ferro suportadas em matriz carbonácea: remoção do corante orgânico azul de metileno em água

In this work were prepared composites of iron oxide and carbonaceous materials in two different weight proportions (Carbon/Fe 1/1 and 1/2). The physico-chemical properties of the composites were determined by temperature programmed reduction (TPR), adsorption/dessorption of N2, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and pulse titration H2. The XRD and XPS analysis showed a cubic iron oxide phase, identified as maghemite, formed over the carbon surface. The particle size of maghemite showed to be within 10-30 nm. Carbon/Fe 1/2 was the most active in MB removal kinetics and ESI-MS studies showed that MB removal by both composites leads to oxidized intermediates.

Utilization of Sn/Nb2O5 composite for the removal of methylene blue

In this work, the oxidation of methylene blue textile dye in the presence of hydrogen peroxide, using niobium oxide impregnated with different proportions of tin (1, 5 and 10% in mass) as catalyst was studied. The materials were characterized by TPR, XPS, XRD and FTIR. The oxidation tests monitored by ESI-MS showed that the composite containing the higher amount of tin was the most efficient in the removal of the dye. The XRD, XPS, and TPR data presented evidence of the formation of the tin-niobium oxide composite containing Sn0 and supported SnO2.

Preparative separation and purification of sesquiterpenoids from tussilago farfara l. by high-speed counter-current chromatography

Preparative high-speed counter-current chromatography (HSCCC) was successfully applied for separation and purification of sesquiterpenoids from an extract of Tussilago farfara L. with a two-phase solvent system composed of n-hexane-ethyl acetate- methanol-water (1:0.5:1.1:0.3, v/v/v/v). The separation produced a total of 32 mg of tussilagone, 18 mg of 14-acetoxy-7β-(3'-ethyl cis-crotonoyloxy)-lα-(2'-methyl butyryloxy)-notonipetranone and 21 mg of 7β-(3'-ethyl cis-crotonoyloxy)-lα-(2'- methyl butyryloxy)-3,14-dehydro-Z-notonipetranone from 500 mg of the crude extract in one step separation with the purity of 99.5, 99.4 and 99.1%, respectively, as determined by HPLC. The structures of these compounds were identified by ESI-MS, ¹H-NMR and 13C-NMR.

A sensitive and robust lc-ms/ms method with monolithic column and electrospray ionization for the quantitation of efavirenz in human plasma: application to a bioequivalence study

An LC-MS/MS method has been developed for the determination of efavirenz (EFZ) in human plasma using hydrochlorothiazide as internal standard (I.S.). An ESI negative mode with multiple reaction-monitoring was used monitoring the transitions m/z 313.88→69.24 (EFZ) and 296.02→204.76 (I.S.). Samples were extracted using liquid-liquid extraction. The total run time was 2.0 min. The separation was achieved with HPLC-RP using a monolithic column. The assay was linear in the concentration range of 100 - 5000 ng mL-1. The mean recovery was 83%. Intra- and inter-day precision were < 9.5% and < 8.9%, respectively and accuracy was in the range ± 8.33%. The method was successfully applied to a bioequivalence study.

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.

Extraction and isolation of dictamnine, obacunone and fraxinellone from Dictamnus dasycarpus Turcz. by supercritical fluid extraction and high-speed counter-current chromatography

Supercritical fluid extraction was used to extract active compounds from the Chinese traditional medicinal D. dasycarpus under the pressure of 30 MPa and temperature of 45 ºC. Further separation and purification was established by high-speed counter-current chromatography (HSCCC) with a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (1:0.8:1.3:0.9, volume ratio). The separation yielded a total of 47 mg of dictamnine, 24 mg of obacunone and 83 mg of fraxinellone from 1.0 g of the crude extract in one step separation with the purity of 99.2, 98.4 and 99.0%, respectively, as determined by HPLC. The chemical structures of these compounds were identified by ESI-MS, IR, ¹H-NMR and 13C-NMR.

Flavonoids and a neolignan glucoside from Guarea macrophylla (Meliaceae)

This work describes the phytochemical study of the methanol extract obtained from leaves of Guarea macrophylla, leading to the isolation and identification of three flavonoid glycosides (quercetin 3-O-β-D-glucopyranoside, quercetin 3-O-b-D-galactopyranoside, kaempferol 7-O-β-D-glucopyranoside) and a neolignan glucoside, dehydrodiconiferyl alcohol-4-β-D-glucoside. All compounds were identified by a combination of spectroscopic methods (¹H, 1D, 2D NMR, 13C and UV), ESI-MS and comparison with the literature data. This is the first report of flavonoids in the genus Guarea and of a neolignan glucoside in the Meliaceae family.

Licanol, um novo flavanol, e outros constituintes de Licania macrophylla Benth

The phytochemical investigation of L. macrophylla Benth led to the isolation of a new flavanol named licanol: (-)-4'-O-methyl-epigallocatechin-3'-O-α-L-rhamnoside, along with nine known compounds, identified as: (-)-4'-O-methyl-epigallocatechin, pheophytin A, 13²-hydroxy-(13²-S)-pheophytin A, pheophytin B, sitosterol, stigmasterol, sitosterol-β-O-glucoside, betulinic alcohol and oleanolic acid. The structures were established based on IR, HR-ESI-MS, and NMR spectrometric data analysis with the aid of 2D techniques. The methanolic extracts of leaves and stem bark as well as the compounds licanol, 13²-hidroxi-(13²-S)-feofitina A, and betulinic alcohol demonstrated antimicrobial activity against several bacterial strains.