982 resultados para beta-D-fructofuranosidase
Resumo:
Invasive candidiasis is associated with high mortality rates (35% to 60%), similar to the range reported for septic shock. The most common types include candidemia, frequently observed in immunocompromised patients, and noncandidemic systemic candidiasis, which constitutes the majority of cases in critically ill patients. However, they are difficult to prove and a definite diagnosis usually occurs late in the course of the disease, thus contributing to their bad prognosis. Early empirical treatment improves the prognosis and currently relies on the positive predictive value (PPV) of risk-assessment strategies (colonization index, Candida score, predictive rules) based on combinations of risk factors, but it may have also largely contributed to the overuse of antifungal agents in critically ill patients. In this context, non- culture-based diagnostic methods, including specific and nonspecific biomarkers, may significantly improve the diagnosis of invasive candidiasis. Candida DNA and mannan antigen/antimannan antibodies are of limited interest for the diagnosis of invasive candidiasis as they fail to identify noncandidemic systemic candidiasis, despite early positivity in candidemic patients. The utility of 1,3-beta-D-glucan (b-D-glucan), a panfungal cell wall antigen, has been demonstrated for the diagnosis of fungal infections in immunocompromised patients. Preliminary data suggest that it is also detectable early in critically ill patients developing noncandidemic systemic candidiasis. To take advantage of the high negative predictive value of risk-assessment strategies and the early increase in specific fungal biomarkers in high-risk patients, we propose a practical 2-step approach to improve the selection of patients susceptible to benefit from empirical antifungal treatment.
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This paper describes the chemical constituents isolated from roots of Pyrostegia venusta. From ethanol extract of the roots allantoin, beta-sitosterol, 3b-O-beta-D-glupyranosylsitosterol and hesperedin were isolated. The structures of these natural products were identified on the basis of spectral data, including 2D NMR of the peracetyl derivative of hesperidin.
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Herein we describe the isolation of homarine and piridiniumbetaine B from the sponge Aaptos sp. Although homarine has a common occurrence among animals, piridiniumbetaine B was only recently isolated from the marine sponge Agelas dispar. The isolation of piridiniumbetaine B from two taxonomically distant marine sponges corroborate previous assumptions that such betaines should be regarded rather as primary metabolites. We have also isolated (9-[5'-(methylthio)-beta-D-xylofuranosyl]adenine (xylosyl-MTA) from the mantle of a nudibranch identified as Doris aff. verrucosa. The occurrence of xylosyl-MTA in the mantle of this animal strongly suggests that it is the same nudibranch species described for the Mediterranean sea. We have been unable to detect any other compound in the mantle extract of D. aff. verrucosa other than xylosil-MTA and sterols. GC-MS analysis of the sterol fraction from the nudibranch and its prey, the sponge Hymeniacidon aff. heliophila, revealed the occurrence of the ubiquitous sterols, cholesterol, brassicasterol, cholestanol, 24-methylcholesterol and 24-ethylcholesterol, as the only common metabolites, therefore precluding any assumption concerning the sequestration of secondary metabolites by the nudibranch from H. aff. heliophila.
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Phytochemical investigation of the flowers of Wedelia paludosa afforded two diterpenes, ent-kaur-16-en-19-oic acid and ent-kaur-9(11),16-dien-19-oic acid, three acylated triterpenes, 3beta-O-hexa-decanoylolean-12-en-28-oic acid, 3beta-O-pentadecanoylolean-12-en-28-oic acid and 3beta-O-tetradecanoylolean-12-en-28-oic acid, and three steroids, stigmasterol, 3beta-O-beta-D-glycopyranosyl sitosterol and 3beta-O-beta-D-glycopyrano-sylstigmasterol. The substances were identified by their spectral data.
Resumo:
An experiment showing the readily available disaccharide (sucrose) as reagent for experiments in undergraduate chemistry laboratory is described. The preparation of 2,3:4,5-di-O-isopropylidene-beta-D-fructopyranose from sucrose is very simple, uses low cost materials, requires two periods of 4 hours and is useful for classroom support in undergraduate courses.
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From the hexane extract of barks of Tapirira guianensis were isolated and identified beta-sitosterol, 3beta-O-beta-D-glucopyranosyl-sitosterol, sitostenone and stigmast-4-en-6beta-ol-3-one. Besides these compounds six alkyl ferulates were obtained including a new one with an unusual odd alkyl chain, nonadecyl coumarate. All structures were determined by spectral data.
Resumo:
From the leaves of Bauhinia forficata kaempferol and four flavonoid glycosides, 3,7-di-O-alpha-L-rhamnopyranosylkaempferol, 3,7-di-O-alpha-L-rhamnopyranosylquercetin, 3-O-[alpha-L-rhamnopyranosyl-(1->6)-beta-D-glucopyranosyl]-7-O-alpha-L-rhamnopyranosylkaempferol and 3-O-[alpha-L-rhamnopyranosyl-(1->6)-beta-D-glucopyranosyl]-7-O-alpha-L-rhamnopyranosylquercetin were obtained. From the flowers only the flavonoid 7-O-alpha-L-rhamnopyranosylkaempferol was isolated. The structures were established by chemical and spectroscopic methods.
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The present communication reports the isolation and identification of four triterpenoid saponins from the chloroform extract of the leaves of Tocoyena brasiliensis: 3-O-beta-D-quinovopyranosyl quinovic acid, 3-O-beta-D-quinovopyranosyl cincholic acid, 3-O-beta-D-glucopyranosyl quinovic acid and the 28-O-beta-D-glucopyranosyl ester derivative of quinovic acid as binary mixtures, respectively. From the ethanol extract a flavonoid identified as ramnazin-3-O-rutinoside was obtained. The structures of these compounds were assigned by data analysis of 1D and 2D NMR spectrometry and comparison with data recorded in the literature for these compounds.
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Phytochemical investigation of the hexane, ethyl acetate and methanolic extracts of roots and leaf stalks of Euterpe precatoria Mart. ("açaí"), afforded stigmast-4-en-6beta-ol-3-one (3); p-hydroxy benzoic acid (4); 3beta-O-D-glucopyranosyl-sitosterol (5); beta-sitosterol palmitate (6); mixtures of beta-sitosterol and stigmasterol (1 and 2), alpha-, beta-amirin and lupeol (7, 8 and 9), friedelin-3-one and 28-hydroxy-friedelin-3-one (10 and 11) and alpha-, beta-D-glucose (12, 13). Except for 1, 2 and 4, the other isolated constituents are described in the genus for the first time. Compounds 3 and 5 gave good results in the brine shrimp bioassay, which detects compounds with potential uses as antitumor agents, pesticides, etc..
Resumo:
This article gives an overview of exopolysaccharides produced by fungi. The structural characterization of beta-D-(1->3) and beta-D-(1->3, 1->6)- glucans is discussed focusing on different chemical and physical procedures. The industrial applications are also considered mainly from the point of view of human health.
Resumo:
Sitosterol, stigmasterol, betulinic acid, lupeol, 3-O-beta-D-glucopiranosylsitosterol, 3-O-alpha-L-rhamnopiranosylchromone, 5,7-dihydroxy-4'-methoxyisoflavone, 3',5,7-trihydroxy-4'-methoxyisoflavone and a mixture of two rel-2R,3S-3-O-alpha-L-rhamnopiranosilflavanonols were isolated from the roots of Andira fraxinifolia. Their structures were established by spectral data analysis.
Resumo:
The phytochemical investigation of Sida galheirensis led to the isolation of 5,4'-dihydroxy-3,7,3´-trimethoxyflavone, 17³-ethoxyphaeoforbide, a rare natural product, 6,7-dimethoxycoumarin, ortho-hydroxybenzoic acid, sitosterol-3-O-beta-D-glucopyranoside, stigmasterol-3-O-beta-D-glucopyranoside, 5,7,4'-trihydroxyflavone, 5,7,3',4'-tetrahydroxyflavone, kaempferol-3-O-beta-D-(6"-E-p-coumaroyl) glucopyranoside and luteolin 7-O-beta-D-glucopyranoside. Their structures were assigned based on spectroscopic analyses, including two-dimensional NMR techniques. Antioxidant activities of hexane, CHCl3, EtOAc, BuOH and EtOH extracts of Sida galheirensis were measured using the 1,2-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging assay. This is also the first work reporting the chemical investigation of Sida galheirensis.
Resumo:
Chemical studies of green leaves of A. tetraphyllum afforded beta-sitosterol, a mixture containing the ethyl esters of long chain carboxylic acids, 30-normethyl-lupan-20-one, hopan-22-ol, phytol, phyten-3(20)-1,2-diol, quercetin and quercetin-3-O-beta-D-glucoside. The structures of the compounds were elucidated by spectroscopic and GC analysis. The allelopathic potentials of the crude ethanolic extract and fractions were evaluated against Lactuca sativa (letuce) and Allium cepa (onion) seeds.
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Phytochemical investigation of the bark of Cenostigma macrophyllum (Leguminosae-Caesapinioideae) resulted in the isolation and identification of valoneic acid dilactone, ellagic acid, lupeol, alkyl ferulate, four free sterols (cholesterol, campesterol, stigmasterol and sitosterol), a mixture of sitosteryl ester derivatives of fatty acids, sitosterol-3-O-beta-D-glucopyranoside, stigmasterol-3-O-beta-D-glucopyranoside and saturated and unsaturated fatty acids. The structures of the isolated compounds were identified by ¹H and 13C NMR spectral analysis and comparison with literature data. The mixtures of 3-beta-hydroxysterols and fatty acids were analysed by GC/MS.
Resumo:
Phytochemical analysis of the kino of Eucalyptus citriodora led to the isolation of 1-O,2-O-digaloil-6-O-trans -p-cumaroil-beta-D-glucopyranoside, 1-O-trans-p-cumaroil-6-O -cinamoil-beta-D-glucopyranoside, alpha and beta 6-O-trans-p-cumaroil-D-glucopyranoside, 7-methylaromadendrin-4'-O-6''- trans-p-cumaroil-beta-D-glucopyranoside, aromadendrin, aromadendrin-7-methyl-ether, naringenin, sakuranetin, kaempferol-7-methyl-ether and galic acid. Structural elucidation of the isolated compounds was established on the basis of spectral data, particularly by the use of 1D NMR and several 2D shift correlated NMR pulse sequences (¹H,¹H-COSY, HMQC, HMBC).