136 resultados para glycoside


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This study describes the chemical and physical-chemical profile of plant drug and ethanolic extract obtained from fruits of Solanum lycocarpum A. St.-Hill. (Solanaceae). The physical and chemical analysis involved the granulometry determination, non-compacted apparent density, loss on drying in oven and in infrared scale, pH, ash values and extractive values. The results determined the physical-chemical characteristics of the drug plant. It was also carried out the microbiological control of the plant drug. The preliminary phytochemical screening featured the presence of tannins, flavonoids and saponins in the plant drug and alkaloids and steroids in the ethanolic exctract. The solamargine and solasonine glycoalkaloids were identified through TLC and GC/ MS. The levels of total phenols and tannins were quantified in the extract (8.90% and 6,85% respectively). Such studies contribute to the chemical identification and quality control of S. lycocarpum fruits. © 2010 Phcog.net.

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Many Chrysobalanaceae species, in special Licania and Parinari, are widely used in folk medicine to treat several diseases. This review describes some aspects of their ethnopharmacology potential, biological activities and the secondary metabolites reported so far for Chrysobalanaceae. The chemical constituents of this family include triterpenoids, diterpenoids, steroids and phenylpropanoids like flavonoids as well as chromones derivatives. © 2012 Springer Science+Business Media Dordrecht.

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Metagenomics has been widely employed for discovery of new enzymes and pathways to conversion of lignocellulosic biomass to fuels and chemicals. In this context, the present study reports the isolation, recombinant expression, biochemical and structural characterization of a novel endoxylanase family GH10 (SCXyl) identified from sugarcane soil metagenome. The recombinant SCXyl was highly active against xylan from beechwood and showed optimal enzyme activity at pH 6,0 and 45°C. The crystal structure was solved at 2.75 Å resolution, revealing the classical (β/α)8-barrel fold with a conserved active-site pocket and an inherent flexibility of the Trp281-Arg291 loop that can adopt distinct conformational states depending on substrate binding. The capillary electrophoresis analysis of degradation products evidenced that the enzyme displays unusual capacity to degrade small xylooligosaccharides, such as xylotriose, which is consistent to the hydrophobic contacts at the +1 subsite and low-binding energies of subsites that are distant from the site of hydrolysis. The main reaction products from xylan polymers and phosphoric acid-pretreated sugarcane bagasse (PASB) were xylooligosaccharides, but, after a longer incubation time, xylobiose and xylose were also formed. Moreover, the use of SCXyl as pre-treatment step of PASB, prior to the addition of commercial cellulolytic cocktail, significantly enhanced the saccharification process. All these characteristics demonstrate the advantageous application of this enzyme in several biotechnological processes in food and feed industry and also in the enzymatic pretreatment of biomass for feedstock and ethanol production. © 2013 Alvarez et al.

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Multifunctional enzyme engineering can improve enzyme cocktails for emerging biofuel technology. Molecular dynamics through structure-based models (SB) is an effective tool for assessing the tridimensional arrangement of chimeric enzymes as well as for inferring the functional practicability before experimental validation. This study describes the computational design of a bifunctional xylanase-lichenase chimera (XylLich) using the xynA and bglS genes from Bacillus subtilis. In silico analysis of the average solvent accessible surface area (SAS) and the root mean square fluctuation (RMSF) predicted a fully functional chimera, with minor fluctuations and variations along the polypeptide chains. Afterwards, the chimeric enzyme was built by fusing the xynA and bglS genes. XylLich was evaluated through small-angle X-ray scattering (SAXS) experiments, resulting in scattering curves with a very accurate fit to the theoretical protein model. The chimera preserved the biochemical characteristics of the parental enzymes, with the exception of a slight variation in the temperature of operation and the catalytic efficiency (k cat/Km). The absence of substantial shifts in the catalytic mode of operation was also verified. Furthermore, the production of chimeric enzymes could be more profitable than producing a single enzyme separately, based on comparing the recombinant protein production yield and the hydrolytic activity achieved for XylLich with that of the parental enzymes. © 2013 Elsevier B.V. All rights reserved.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Pós-graduação em Agronomia (Energia na Agricultura) - FCA

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Este estudo visou identificar substâncias biologicamente ativas e o potencial alelopático de esteroides glicosilados, provenientes das sementes de Annona crassiflora. O isolamento dos esteroides glicosilados foi realizado com a separação dos constituintes químicos do extrato bruto de acetato de etila em coluna cromatográfica, sendo a completa elucidação estrutural por meio de espectroscopia de RMN 1H. Testes de germinação com as espécies Euphorbia heterophylla e Ipomoea grandifolia foram conduzidos em câmaras tipo BOD a 25ºC e fotoperíodo de 12 horas, monitorados durante 10 dias com avaliação diária, nas concentrações de 0, 20, 40, 80 e 100 mg L-1 dos materiais isolados. Utilizando as mesmas concentrações, os experimentos de desenvolvimento de radícula e hipocótilo foram mantidos em câmara de germinação a 25ºC e fotoperíodo de 24 horas, com avaliação no décimo dia. Após o extrato de acetato de etila ser submetido ao fracionamento, verificou-se a presença de sinais característicos de fitoesteróis no espectro do RMN 1H, resultando em uma mistura de estigmasterol glicosilado e sitosterol glicosilado. Os resultados indicam que as substâncias estigmasterol e sitosterol não proporcionaram inibição na germinação e no índice de velocidade de germinação (IVG) de E. heterophylla e I. grandifolia. Por outro lado, estigmasterol e sitosterol interferiram no desenvolvimento de radícula e hipocótilo de E. heterophylla.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Asclepias subulata Decne. is a shrub occurring in Sonora-Arizona desert (Mexico-USA). The ethnic groups, Seris and Pimas, use this plant for the treatment of sore eyes, gastrointestinal disorders and cancer. To isolate the compounds responsible for antiproliferative activity of the methanol extract of A. subulata. A bioguided fractionation of methanol extract of A. subulata was performed using MTT assay to measure the antiproliferative activity of different compounds on three human cancer cell lines (A549, LS 180 and PC-3), one murine cancer cell line (RAW 264.7) and one human normal cell line (ARPE-19). The methanol extract was partitioned with hexane, ethyl acetate and ethanol. The active fractions, ethanol and residual, were fractioned by silica-column chromatography and active sub-fractions were separated using HPLC. The chemical structures of isolated compounds were elucidated with different chemical and spectroscopic methods. A new cardenolide glycoside, 12, 16-dihydroxycalotropin, and three known, calotropin, corotoxigenin 3-O-glucopyranoside and desglucouzarin, were isolated of active sub-fractions. All isolated compounds showed a strong antiproliferative activity in human cancer cells. Calotropin was the more active with IC50 values of 0.0013, 0.06 and 0.41 µM on A549, LS 180 and PC-3 cell lines, respectively; while 12, 16-dihydroxycalotropin reached values of 2.48, 5.62 and 11.70 µM, on the same cells; corotoxigenin 3-O-glucopyranoside had IC50 of 2.64, 3.15 and 6.62 µM and desglucouzarin showed values of 0.90, 6.57 and 6.62, µM. Doxorubicin, positive control, showed IC50 values of 1.78, 6.99 and 3.18 µM, respectively. The isolated compounds had a weak effect on murine cancer cells and human normal cells, exhibiting selectivity to human cancer cells. In this study, we found that 12, 16-dihydroxicalotropin, calotropin, corotoxigenin 3-O-glucopyranoside and desglucouzarin are responsible of antiproliferative properties of A. subulata, and that these compounds are highly selective to human cancer cells. Further studies are needed in order to establish the action mechanisms of the isolated compounds.

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The aim of the present study was to investigate the effect of isofl avones supplementation of a fermented soy product on its sensory acceptance, physicochemical properties and probiotic cell viable count. Additionally we also investigated the ability of the mixed starter cultures (Enterococcus faecium CRL 183 and Lactobacillus helveticus 416) to modify the isofl avones profi le of soy product during the fermentation process. Three products were analysed: soy product fermented with E. faecium CRL 183 and L. helveticus 416, isofl avonessupplemented soy product (fermented with E. faecium CRL 183 and L. helveticus 416; 50mg/100g, Isofl avin®, Galena, Brazil) and unfermented soy product. A panel of judges evaluated the acceptability of the samples on a nine point structured hedonic scale. The chemical composition namely fat, protein, ash and total carbohydrate contents, pH, enumeration of viable Lactobacillus spp. and Enterococcus spp. and quantifi cation of isofl avones using HPLC were investigated. All determinations were conducted after 7 days storage at 10°C. The sensorial acceptance was reduced in the isofl avones-supplemented soy product, but this effect was not signifi cant compared to the sample without isofl avones addition. Chemical composition did not differ (p<0.05) among the samples. Cell viable counts were reduced and total fermentation time was longer in the isofl avonessupplemented soy product, suggesting that the isofl avone addition could inhibit the starter cultures. However, all the products may be considered probiotic since they exhibited lactic acid bacterial populations varying from 2.3 x 109 up to 1.22 x 1010 CFU/mL. Fermentation of soymilk did not change the isofl avones profi le. In conclusion, it was possible to obtain a fermented soy product containing a high isofl avones concentration, adequate sensory and chemical characteristics and lactic acid bacterial viability suffi ciently high to characterize the product as a probiotic. The mixed starter culture was not able to convert the glycoside isofl avones into aglycone or produce equol during the fermented soy product processing.