Ora in mostra 1 - 10 di 3908
  • Pubblicazione
    Synthesis and Biological Activity of Potent HIV-1 Protease Inhibitors Based on Phe-Pro Dihydroxyethylene Isosteres
    ( 2012) ; ;
    BUDAL, SARA
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    CAMPANER, PIETRO
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    DINON, FRANCESCA
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    ;
    R. Argirova
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    P. Genova
    ;
    V. Atanassov
    ;
    A. Hinkov
    Peptidomimetic inhibitors of HIV-1 PR are still a key resource in the fight against AIDS. Here we describe the synthesis and biological activity of HIV-1 PR inhibitors based on four novel dihydroxyethylene isosteres of the Phe-Pro and Pro- Pro dipeptides. The isosteres, containing four stereogenic centers, were synthesized in high yield and excellent stereoselectivity via the cyclization of epoxy amines derived from α-amino acids. The inhibitors were assembled by coupling the isosteres with suitable flanking groups and were screened against recombinant HIV PR showing activities in the subnanomolar to micromolar range. Two Phe-Pro-based inhibitors active at the nanomolar level were further investigated: both inhibitors combine the ability to suppress HIV-1 replication in infected MT-2 cells with low cytotoxicity against the same cells, thereby displaying a high therapeutic index. These results demonstrate the potential of the new Phe-Pro dihydroxyethylene isostere as a core unit of powerful HIV-1 PR inhibitors.
    WOS© Citazioni 10Scopus© Citazioni 9
  • Pubblicazione
    Molecular-frame photoelectron angular distribution imaging studies of OCS S1s photoionization
    ( 2012)
    Bomme C.
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    Guillemin R.
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    Marin T.
    ;
    Journel L.
    ;
    Marchenko T.
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    Trcera N.
    ;
    Kushawaha R. K.
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    Piancastelli M. N.
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    Simon M.
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    ;
    DECLEVA, PIETRO
    Molecular-frame photoelectron angular distributions (MFPADs) in carbonyl sulfide at selected photon energies above the sulfur 1s ionization threshold have been measured using a recently developed vector-correlation experimental setup and theoretically calculated using the time-dependent DFT method. For this linear molecule, the selection of the fragmentation channel CO+ + S+ is an effective method to fix the molecular frame. The experimental results are found in good agreement with the calculated MFPADs.
    Scopus© Citazioni 10WOS© Citazioni 10
  • Pubblicazione
    Recoil frame photoelectron angular distributions in core O 1s ionization of H2CO
    ( 2012) ;
    DECLEVA, PIETRO
    ;
    Adachi J.
    ;
    Miyauchi N.
    ;
    Yamazaki M.
    ;
    Yagishita A.
    WOS© Citazioni 4Scopus© Citazioni 4
  • Pubblicazione
    Degradation of Silver-Polysaccharide Nanocomposite in Solution and as Coating on Fiber-Reinforced Composites by Lysozyme and Hydrogen Peroxide
    ( 2012)
    Nganga S.
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    TRAVAN, Andrea
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    ; ;
    PAOLETTI, SERGIO
    ;
    Vallittu P. K.
    Within this study we analyzed the degradation resistance of Chitlac both in solution and as a coating film in aqueous media upon exposure to the enzymatic attack of lysozyme or to the oxidant effect of H2O2. Possible coating degradation in such conditions was evaluated by measuring the amount of both polysaccharide and silver released in solution.
    WOS© Citazioni 8
  • Pubblicazione
    Density functional theory simulation of NEXAFS spectra of molecules adsorbed on surfaces: C2H4 on Si(100) case study
    ( 2012) ; ;
    DE FRANCESCO, RENATO
    ;
    ROMEO, MICHELE
    ;
    The carbon 1s X-ray absorption spectra of ethylene adsorbed on the Si (100) surface have been simulated using density functional theory (DFT) in conjunction with the transition-state (TS) method. Finite size cluster models are adopted to describe the spectra of two different interaction modes of C2H4 with the surface, the on-top and bridge adsorption geometries. The accurate modeling of the clusters is tackled by a preliminar optimization of the surface and of the molecules adsorbed on it performed by a periodic slab methodology in the frame of density functional theory (DFT). The suitable clusters for the spectra calculations have been cut out from the optimized periodic structures. Total spectra as well as angle resolved spectra have been simulated. The comparison between the total spectra of the adsorbate models and that of the free ethylene highlights the change of hybridization of the carbon atoms upon the adsorption. The polarized spectra simulated for the ethylene adsorbed in the on-top geometry reproduce correctly the main experimental features and their trend with the change of the polarization while a poor match with the experimental trend is obtained in the case of the bridge adsorption geometry. The results show that a careful analysis of the calculated polarized spectra can provide important information on specific details of the adsorbtion geometries. The methodology employed has proven to be able to describe the K-shell spectra of this kind of systems as well as affordable to be applied to larger adsorbed molecules.
    WOS© Citazioni 15Scopus© Citazioni 16
  • Pubblicazione
    Self-organization of mixtures of fluorocarbon and hydrocarbon amphiphilic thiolates on the surface of gold nanoparticles
    ( 2012) ;
    Gentilini C.
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    BIDOGGIA, SILVIA
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    Pace A.
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    Franchi P.
    ;
    Lucarini M.
    ;
    ; ;
    Self-assembled monolayers composed of mixture of thiolate molecules, featuring hydrocarbon or perfluorocarbon chains (H- and F-chains) terminating with a short poly(oxoethylene) (PEG) moiety is the most extreme example of surfactants immiscibility on gold nanoparticles (NPs) reported so far. The phase-segregation between H-chains and F-chains and the consequent, peculiar folding of PEG chains are responsible for the increased affinity of a selected radical probe for the fluorinated region, which increases as the size of the fluorinated domains decreases, independently of the shape of such domains. This feature has been revealed by ESR measurements and an in silico innovative multiscale molecular simulations approach in explicit water. Our results reveal an underlying mechanism of a transmission of the organization of the monolayer from the inner region close to the gold surface toward the external hydrophilic PEG region. Moreover, this study definitively proves that a mixed monolayer is a complex system with properties markedly different from those characterizing the parent homoligand monolayers.
    WOS© Citazioni 35
  • Pubblicazione
    H2 Production by Renewables Photoreforming on Pt–Au/TiO2 Catalysts Activated by Reduction
    ( 2012)
    Gallo A
    ;
    ;
    Marelli M.
    ;
    Minguzzi A.
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    GOMBAC, VALENTINA
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    Psaro R.
    ;
    ;
    Dal Santo V.
    Bimetallic Pt–Au nanoparticles supported on reduced anatase nanocrystals represent a new class of promising photocatalysts with high activity in hydrogen production by photoreforming of aqueous solution of renewable feedstock, such as ethanol and glycerol. The catalysts are easily obtained by metal impregnation of commercial TiO2, followed by a reductive treatment. Remarkably, deeper catalyst pre-reduction results in enhanced photoactivity. When ethanol is used as sacrificial agent, under both UV-A or simulated sunlight irradiation, H2 is the most abundant product in the gas stream whereas, in the case of glycerol, significant amounts of CO2 have also been detected, indicating a more efficient oxidation of the organic sacrificial agent. The presence of bimetallic Pt–Au nanoparticles and of Ti3+ sites/O2− vacancies in the bulk structure of titania are two key parameters to maximize light absorption and feedstock activation, finally resulting in good photocatalytic performances.
    WOS© Citazioni 93Scopus© Citazioni 100
  • Pubblicazione
    Factors that influence the antiproliferative activity of half sandwich RuII-[9]aneS3 coordination compounds: activation kinetics and interaction with guanine derivatives.
    ( 2012)
    Ana Rilak
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    Ioannis Bratsos
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    ZANGRANDO, ENNIO
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    Jakob Kljun
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    Iztok Turel
    ;
    Zivadin D. Bugarcic
    ;
    Half sandwich Ru(II) – [9]aneS3 complexes ([9]aneS3 = 1,4,7-trithiacyclononane) are being studied for their antiproliferative activity. We investigated here the activation kinetics of three such complexes, namely [Ru([9]aneS3)(en)Cl](PF6) (1), [Ru([9]aneS3)(bpy)Cl](PF 6 ) (2) and [Ru([9]aneS3)(pic)Cl] (3) (en = 1,2-diaminoethane, pic = picolinate), and their interaction with DNA model bases. The aim of the study was to assess how they are affected by the nature and charge of the chelating ligand. The model reactions of 1 – 3 with the guanine derivatives 9-methylguanine (9MeG), guanosine (Guo), and guanosine 5 ′ -monophosphate (5 ′ -GMP) were studied by NMR spectroscopy. All reactions lead, although with different rates and to different extents, to the formation of monofunctional adducts with the guanine derivatives N7-bonded to the Ru center. Two products, the complexes [Ru([9]aneS3)(en)(9MeG-N7)](PF 6 ) 2 (4) and [Ru([9]aneS3)(pic)(9MeG-N7)](PF 6 ) (10), were structurally characterized also by X-ray crystallography. The structure of 4 is stabilized by strong intramolecular H-bonding between an NH of en and the carbonyl O6 of 9MeG. The kinetics of aquation and anation of complexes 2 and 3, as well as the kinetics and the mechanism of the reaction of complexes 1 – 3 with the biologically more relevant 5 ′ -GMP ligand were studied by UV-Vis spectroscopy. The rate of the reaction of 1 – 3 with 5 ′ -GMP depends on the nature of the chelating ligand rather than on the charge of the complex, decreasing in the order 3 ≈ 2 > 1.
    Scopus© Citazioni 19WOS© Citazioni 19
  • Pubblicazione
    Enzymatic kinetic resolution of hydroxystearic acids: A combined experimental and molecular modelling investigation
    ( 2012)
    EBERT, CYNTHIA
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    ; ;
    FOSCATO, MARCO
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    ; ;
    PITACCO, GIULIANA
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    C. Boga
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    P. Caruana
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    G. Micheletti
    ;
    N. Calonghi
    ;
    L. Masotti
    Enantioenriched 7-, 8-, 9-, and 10-hydroxystearic acids (HSA) were obtained, for the first time, by kinetic resolution of their racemates with lipases CALB and PS, in the presence of vinyl acetate. Among them, the best results were obtained for 7-HSA and 9-HSA, whose enantiomeric excess was around 55%. The same resolutions carried out on the hydroxy esters completely failed. For the acid substrates neither the Kazlauskas’ rule nor the 3D-QSAR model could be applied, since both models are focused on the CALB alcohol-pocket evaluation and not on the acyl-pocket one. Therefore, a semiquantitative approach was used, whose results were in accordance with our findings, as far as the absolute configuration of the product is concerned.
    WOS© Citazioni 15Scopus© Citazioni 17
  • Pubblicazione
    Exceptional Activity for Methane Combustion over Modular Pd@CeO2 Subunits on Functionalized Al2O3
    ( 2012)
    CARGNELLO, MATTEO
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    Delgado Jaén J. J.
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    Hernández Garrido J. C.
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    Bakhmutsky K.
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    Calvino Gámez J. J.
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    Gorte R. J.
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    There is a critical need for improved methane-oxidation catalysts to both reduce emissions of methane, a greenhouse gas, and improve the performance of gas turbines. However, materials that are currently available either have low activity below 400°C or are unstable at higher temperatures. Here, we describe a supramolecular approach in which single units composed of a palladium (Pd) core and a ceria (CeO2) shell are preorganized in solution and then homogeneously deposited onto a modified hydrophobic alumina. Electron microscopy and other structural methods revealed that the Pd cores remained isolated even after heating the catalyst to 850°C. Enhanced metal-support interactions led to exceptionally high methane oxidation, with complete conversion below 400°C and outstanding thermal stability under demanding conditions.
    WOS© Citazioni 633Scopus© Citazioni 659