982 resultados para SECONDARY METABOLITES


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The spread of sociocultural focuses and critical literacy studies, which offer an holistic perspective on communicative skills, has reached our country at a time when the commonest environment for writing is the internet, and information technologies have transformed writing with new channels, genres, forms of preparation and languages. Thanks to these changes, educational programmes now include new concepts of literacy related to knowledge and the use of digital environments. This paper explores the impact of introducing these new communicative environments to teaching written expression at secondary level and puts forward some ideas to link learning how to write to present communicative contexts and established practices. Without forgetting the achievements of recent decades, we need to bring about a series of changes to bring new learned writing practices to class and leave behind others we had championed as necessary when the goal was to move beyond exclusively linguistic or grammatical approaches

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Mathematics has formed part of all our daily lives since the most remote origins of our civilization, although on too many occasions schools have done little for this functional view of mathematics reclaiming the formal role of this discipline in detriment of its more practical and applied element. From this perspective the curriculum organized by competence arises due to the need to fill this vacuum and allow our students to function better in the constant elements of real situations which they are going to have to resolve throughout their lives. The specifying of this general view of mathematic competence in the numeric competence should allow all our students to progressively acquire numeric sense, that is, that they have the capacity to apply good quantitative ideas in real situations

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In the article we resume four experiments of an interdisciplinary nature carried out in four different secondary education centres. The nexus of the union of these didactic proposals is that of looking at values in sport and the critical capacity of the students from distinct perspectives: violence, mass media, politics and gender and the treatment of body in our society

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A culture of P. brasilianum, isolated from soil collected at the Serra do Cipó National Park, in Minas Gerais State (Brazil), was grown for 25 days on a dextrose-peptone-salts medium. The corresponding ethylacetate extract was column chromatographed and four compounds were isolated: austin, dehydroaustin, D-mannitol and penicillic acid. This is, in the best of our knowledge, the first time that the meroterpenes austin and dehydroaustin have been isolated from this species. Activity of the extract and isolated compounds was tested against six bacteria and for acetylcholinesterase inhibition. Penicillic acid showed high activity in both tests.

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An efficient synthesis of the marine metabolite 3-bromoverongiaquinol (1) and the first total synthesis of 5-monobromocavernicolin (2), both isolated from the marine sponge Aplysina cavernicola, have been described based on the 1,2 addition of the lithium enolate of N,O-bistrimethylsilylacetamide (BSA, 4) to 1,4-benzoquinone (3). Bromination and purification of the crude product on silica gel chromatography provided 3-bromoverongiaquinol (1) in 50% overall yield. Under alkaline conditions, the crude product of the bromination reaction was converted to 5-monobromocavernicolin (2) in 20% yield which was also obtained in 13% yield (25% yield based on recovered starting material) from 3-bromoverongiaquinol (1).

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Sensitive and selective spectrophotometric and spectrofluorimetric methods have been developed for determination of some drugs such as Pramipexole, Nebivolol, Carvedilol, and Eletriptan, which commonly contain secondary amino group. The subject methods were developed via derivatization of the secondary amino groups with 7-Chloro-4-Nitrobenzofurazon in borate buffer where a yellow colored reaction product was obtained and measured spectrophotometrically or spectrofluorimetrically. Concentration ranges were found as 2.0 to 250 μg mL-1 and 0.1 to 3.0 μg mL-1, for spectrophotometric and spectrofluorimetric study, respectively. The described methods can be easily applied by the quality control laboratories in routine analyses of these drugs in pharmaceutical preparations.

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The alkaloid glandicoline B (1) and six other compounds: ergosterol (2), brassicasterol (3), ergosterol peroxide (4), cerevisterol (5), mannitol (6) and 1-O-α-D-glucopyranoside (7) were isolated from Penicillium sp. strain PBR.2.2.2, a fungus from Mauritia flexuosa roots. The structures of the isolated metabolites were established by spectral analysis. MeOH extract of the fungal mycelium at 500 µg mL-1 exhibited antimicrobial activity against Staphylococcus aureus and the compound 1 at 100 µg mL-1 was active against S. aureus, Micrococcus luteus and Escherichia coli. The relationship between the bioactive properties of the fungus PBR.2.2.2 and those achieved for glandicoline B, as well the potential of this substance as bactericide is discussed.

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Primary, secondary and tertiary alcohols can be easily distinguished due to their reactivity towards tribromoisocyanuric acid (TBCA). The test is performed by adding TBCA to the alcohol in a test tube heated in a boiling water bath. Orange color develops in the tube containing the primary alcohol, light yellow is observed in the tube containing the secondary alcohol while the tertiary alcohol results in a colorless mixture.

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A bioassay-guided fractionation of culture filtrates of the fungus Alternaria euphorbiicola, a pathogen of the weed Euphorbia heterophylla, led to the isolation of anhydromevalonolactone (1), tyrosol (2), (R)-( - )-mevalonolactone (3), and cycloglycylproline (4). When tested on the punctured leaves of the host plant, these compounds produced bleached lesions with dark brown margins at concentrations as low as 80 µM. When tested on the leaves of other relevant weeds, only cycloglycylproline showed selective activity against E. heterophylla. This is the first report on the isolation of phytotoxins from A. euphorbiicola and on the phytotoxicity of anhydromevalonolactone, (R)-( - )-mevalonolactone, and cycloglycylproline.

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Certain sweet sorghums (Sorghum bicolor) inhibit the secondary sporulation of Claviceps africana, which occurs on exuded ergot honeydew when the parasite is supplied with excess sucrose, which is then transformed to unique free oligosaccharides fructosyl - mannitol and difructosyl - mannitol with spore germination inhibiting properties. Five accessions (BRA-035726-SUGAR DRIP, BRA-035696-THEIS, BRA-036013-MN-4578, BRA-035947-MN-4418 and CMSXS-633) of sweet sorghum were selected among 50 evaluated. These five accessions failed to support secondary sporulation on the "honeydew" exuded from infected florets. There was a higher concentration (%w/v) of the free oligosaccharides on the honeydew of these accessions when compared to a hybrid male-sterile grain sorghum. Therefore, a possible strategy would be seek to incorporate a sweet character into "A" lines for hybrid seed production in order to restrict secondary disease spread.

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The chemical indexes, suggested by Gottlieb et al., have not been used before regarding evolutionary tendency of species in the Swartzia genus. However, the importance of this work encouraged for an analysis of the Swartzia genus using the metabolites isolated from nine species. The analysis, based on calculated chemical indexes, provided an evolutionary tendency for these plants, which correlates with the classification based on morphological analysis.

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The use of enantiopure intermediates for drug synthesis is a trend in pharmaceutical industry. Different physiological effects are associated with the enantiomers of chiral molecules. Thus, the safety profile of a drug based on an enantiopure active pharmaceutical ingredient is more reliable. Biocatalysis is an important tool to access enantiopure molecules. In biocatalysis, the advantage of selectivity (chemo-, regio- and stereoselectivity) is combined with the benefits of a green synthesis strategy. Chemoenzymatic syntheses of drug molecules, obtained by combining biocatalysis with modern chemical synthesis steps usually consists of fewer reaction steps, reduced waste production and improved overall synthetic efficiency both in yields and enantio- and/or diastereoselectivities compared with classical chemical synthesis. The experimental work together with the literature review clearly indicates that lipase catalysis is highly applicable in the synthesis of enantiopure intermediates of drug molecules as the basis to infer the correct stereochemistry. By lipase catalysis, enantiopure secondary alcohols used as intermediates in the synthesis of Dorzolamide, an antiglaucoma drug, were obtained. Enantiopure _-hydroxy nitriles as potential intermediates for the synthesis of antidepressant drugs with 1-aryl-3- methylaminopropan-1-ol structure were also obtained with lipases. Kinetic resolution of racemates was the main biocatalytic approach applied. Candida Antarctica lipase B, Burkholderia cepacia lipase and Thermomyces lanuginosus lipase were applied for the acylation of alcohols and the alcoholysis of their esters in organic solvents, such as in diisopropyl ether and tert-butyl methyl ether. Candida Antarctica lipase B was used under solvent free conditions for the acylation of ethyl 3-hydroxybutanoate.

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Microorganisms for biological control are capable of producing active compounds that inhibit the development of phytopathogens, constituting a promising tool toob tain active principles that could replace synthetic pesticides. This study evaluatedtheability of severalpotentialbiocontrol microorganismsto produce active extracellular metabolites. In vitro antagonistic capability of 50 bacterial isolates from rhizospheric soils of "criolla" potato (Solanum phureja) was tested through dual culture in this plant with different plant pathogenic fungi and bacteria. Isolates that showed significantly higher antagonistic activity were fermented in liquid media and crude extracts from the supernatants had their biological activities assessed by optical density techniques. Inhibitory effecton tested pathogens was observed for concentrations between 0.5% and 1% of crude extracts. There was a correlation between the antimicrobial activity of extracts and the use of nutrient-rich media in bacteria fermentation. Using a bioguided method, a peptidic compound, active against Fusarium oxysporum, was obtained from the 7ANT04 strain (Pyrobaculum sp.). Analysis by nuclear magnetic resonance and liquid chromatography coupled to mass detector evidenced an 11-amino acid compound. Bioinformatic software using raw mass data confirmed the presence of a cyclic peptide conformed by 11 mostly non-standard amino acids.