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1.
Barbara La Ferla Luigi Lay Laura Poletti Giovanni Russo Luigi Panza 《Journal of carbohydrate chemistry》2013,32(3):331-343
ABSTRACT Three glycosyllactosides, contained in the neutral fraction of human milk oligosaccharides, were synthesised in a simple and straightforward manner through a sequence based on a chemo-enzymatic approach. Lipase catalysed regioselective 6'-O-acylation of benzyl β-lactoside, followed by the introduction of an isopropylidene group and acetylation afforded, depending on the reaction conditions, compounds 4a and 4b, which allow selective access to positions 3, 3' and 6'. Glycosylation with proper donors gave trisaccharides 6, 9 and 12. 相似文献
2.
Summary The ion-assisted regrowth of chemical-vapour deposited Si films onto (100) Si substrates is reported. The regrowth was induced
by a 600 keV Kr++ beam at doses in the range (2·1015÷6·1015)/cm2 and at a dose rate of 1·1012/cm2s. The target temperature was set at 450°C. During irradiations the crystal-amorphous interface velocity was measuredin situ by monitoring the reflectivity of a He-Ne laser light focused onto the sample surface. After irradiation some samples were
also analysed by Rutherford backscattering in combination with the channelling effect and by transmission electron microscopy.
The growth rate of deposited layers depends on the cleaning procedure performed prior to deposition,i.e on the total amount of oxygen present at the deposited layer/substrate interface. Moreover, twinned material is observed
in the recrystallized layers and its concentration is strongly dependent on substrate cleaning. These phenomena are explained
in terms of a decrease in the ion-assisted growth rate in the presence of high oxygen concentrations. The data are discussed
and compared with those obtained during pure thermal annealing.
To speed up publication, the authors of this paper has agreed to not receive the proofs for correction. 相似文献
3.
Barbara La Ferla Laura Russo Cristina Airoldi Francesco Nicotra 《Tetrahedron: Asymmetry》2009,20(6-8):744-745
A C-glycoside mimetic of l-galactose 1-diphosphate, a potential ligand of GDP-l-galactose hydrolase, an enzyme involved in the biosynthesis of vitamin C, has been designed, stereoselectively synthesised by C-allylation of tribenzylated l-fucose, by periodate-osmium tetroxide degradation of the double bond, by condensation of the obtained aldehydes with benzylacetate and by deprotection. The obtained mimetic was linked to a sepharose resin. 相似文献
4.
La Ferla B Airoldi C Zona C Orsato A Cardona F Merlo S Sironi E D'Orazio G Nicotra F 《Natural product reports》2011,28(3):630-648
Cancer is one of the major causes of death worldwide. As a consequence, many different therapeutic approaches, including the use of glycosides as anticancer agents, have been developed. Various glycosylated natural products exhibit high activity against a variety of microbes and human tumors. In this review we classify glycosides according to the nature of their aglycone (non-saccharidic) part. Among them, we describe anthracyclines, aureolic acids, enediyne antibiotics, macrolide and glycopeptides presenting different strengths and mechanisms of action against human cancers. In some cases, the glycosidic residue is crucial for their activity, such as in anthracycline, aureolic acid and enediyne antibiotics; in other cases, Nature has exploited glycosylation to improve solubility or pharmacokinetic properties, as in the glycopeptides. In this review we focus our attention on natural glycoconjugates with anticancer properties. The structure of several of the carbohydrate moieties found in these conjugates and their role are described. The structure–activity relationship of some of these compounds, together with the structural features of their interaction with the biological targets, are also reported. Taken together, all this information is useful for the design of new potential anti-tumor drugs. 相似文献
5.
Cipolla L La Ferla B Gregori M 《Combinatorial chemistry & high throughput screening》2006,9(8):571-582
Oligosaccharide processing enzymes such as glycosidases and glycosyltransferases are important classes of biocatalysts involved in synthesising specific oligosaccharide structures on proteins and lipids. These enzymes are known to be involved in a wide range of important biological processes, such as intestinal digestion, post-translational processing of glycoproteins, lysosomal catabolism of glycoconjugates and inter-cellular recognition events. Inhibition of these enzymes can disrupt biosynthesis of oligosaccharides, thus interfering in all of these processes. Hence, "glyco-enzyme" inhibitors might have enormous therapeutic potential in many diseases such as viral infection, cancer and diabetes. This very important prospect has led to increasing interest and demand for these compounds. Interference in oligosaccharide processing is the basis for the anti-influenza neuraminidase inhibitors that have recently been marketed and also for the potential use of glycosidase inhibitors against HIV, Gaucher's disease, hepatitis, and cancer. Since a rational design and synthesis of inhibitors are often extremely difficult due to the limited information regarding the structure of the active site, combinatorial approaches are particularly promising. This review will focus on synthetic efforts for the preparation of combinatorial libraries of glyco-enzyme inhibitors. 相似文献
6.
7.
Alternative, non-electrochemistry-based technologies for continuous glucose monitoring are needed for eventual use in diabetes mellitus. As part of a programme investigating fluorescent glucose sensors, we have developed fibre-optic biosensors using glucose/galactose binding protein (GBP) labelled with the environmentally sensitive fluorophore, Badan. GBP-Badan was attached via an oligohistidine-tag to the surface of Ni-nitrilotriacetic acid (NTA)-functionalized agarose or polystyrene beads. Fluorescence lifetime increased in response to glucose, observed by fluorescence lifetime imaging microscopy of the GBP-Badan-beads. Either GBP-Badan agarose or polystyrene beads were loaded into a porous chamber at the end of a multimode optical fibre. Fluorescence lifetime responses were recorded using pulsed laser excitation, high speed photodiode detection and time-correlated single-photon counting. The maximal response was at 100 mM glucose with an apparent K(d) of 13 mM (agarose) and 20 mM (polystyrene), and good working-day stability was demonstrated. We conclude that fluorescence lifetime fibre-optic glucose sensors based on GBP-Badan are suitable for development as clinical glucose monitors. 相似文献
8.
Calixarene–iminosugar derivatives bearing four 1-deoxynojirimycin units at the upper or lower rim of calix[4]arenes in a fixed cone conformation were synthesized by copper-catalyzed azide-alkyne cycloaddition (CuAAC) and their inhibitory activity was evaluated against five glycosidases. Modest but significant affinity enhancements of up to seven per 1-deoxynojirimycin unit over the monovalent iminosugar derivative were observed for the inhibition of Jack bean (Canavalia ensiformis) α-mannosidase. It was also demonstrated that the residual copper ions did not contribute to the inhibitory properties of the newly prepared calixarene-based multivalent iminosugars. 相似文献
9.
Barbara La Ferla 《Monatshefte für Chemie / Chemical Monthly》2002,133(4):351-368
Summary. Stereo- and regioselective acylation and deacylation of carbohydrates can be achieved using lipases as biocatalysts. These
enzymes are extremely versatile, quite stable in aqueous and organic solvents, easily available, and easy to handle. Recently,
they have become the object of site directed mutagenesis which suggests that they soon could be ‘built ad hoc’ for specific necessities.
Received September 11, 2001. Accepted November 19, 2001 相似文献
10.
Helio G. Bonacorso Adriana Ferla Cleber A. Cechinel Nilo Zanatta Marcos A. P. Martins 《Journal of heterocyclic chemistry》2008,45(2):483-487