http://http://dspace.unitus.it:80 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. 2013-05-22T15:42:54Z http://hdl.handle.net/2067/1796 Title: Oxidative Functionalisation of Lignin by Layer-by-Layer Immobilised Laccases and Laccase Microcapsules Authors: Crestini, Claudia; Perazzini, Raffaella; Saladino, Raffaele Abstract: Laccase was either supported onto alumina particles or physically entrapped inside microcapsules. In both cases, the enzyme was protected by coating with oppositely charged polyelectrolytes by means of the layer-by-layer technique. The activities of these laccase particles and microcapsules were studied on softwood milled wood and kraft residual lignins, in the presence and absence of different mediators. Quantitative 31P NMR was used to determine the structural modifications induced in the lignin structures. Compared to the native enzyme, the laccase particles and microcapsules were found to be more reactive, showing higher conversions. Irrespective of the experimental conditions, the oxidation efficiency was enhanced by the presence of 1-hydroxybenzotriazole or violuric acid as the oxidation mediator. Differently immobilised laccases showed distinct reaction selectivities in the oxidative pattern of lignin. Description: L'articolo è disponibile sul sito dell'editore: http://www.sciencedirect.com 2009-12-31T23:00:00Z http://hdl.handle.net/2067/1790 Title: A novel and efficient oxidative functionalization of lignin by layer-by-layer immobilised Horseradish peroxidase Authors: Perazzini, Raffaella; Saladino, Raffaele; Guazzaroni, Melissa; Crestini, Claudia Abstract: Horseradish peroxidase (HRP) was chemically immobilised onto alumina particles and coated by polyelectrolytes layers, using the layer-by-layer technique. The reactivity of the immobilised enzyme was studied in the oxidative functionalisation of softwood milled wood and residual kraft lignins and found higher than the free enzyme. In order to investigate the chemical modifications in the lignin structure, quantitative 31P NMR was used. The immobilised HRP showed a higher reactivity with respect to the native enzyme yielding extensive depolymerisation of lignin. Description: L'articolo è disponibile sul sito dell'editore: http://www.sciencedirect.com 2010-12-31T23:00:00Z http://hdl.handle.net/2067/1798 Title: Current advances in anti-influenza therapy Authors: Saladino, Raffaele; Barontini, Maurizio; Crucianelli, Marcello; Nencioni, Lucia; Sgarbanti, Rossella; Palamara, Anna Teresa Abstract: Every year, influenza epidemics cause numerous deaths and millions of hospitalizations, but the most frightening effects are seen when new strains of the virus emerge from different species (e.g. the swine-origin influenza A/H1N1 virus), causing world-wide outbreaks of infection. Several antiviral compounds have been developed against influenza virus to interfere with specific events in the replication cycle. Among them, the inhibitors of viral uncoating (amantadine), nucleoside inhibitors (ribavirin), viral transcription and neuraminidase inhibitors (zanamivir and oseltamivir) are reported as examples of traditional virus-based antiviral strategies. However, for most of them the efficacy is often limited by toxicity and the almost inevitable selection of drug-resistant viral mutants. Thus, the discovery of novel anti-influenza drugs that target general cell signaling pathways essential for viral replication, irrespective to the specific origin of the virus, would decrease the emergence of drug resistance and increase the effectiveness towards different strains of influenza virus. In this context, virus-activated intracellular cascades, finely regulated by small changes in the intracellular redox state, can contribute to inhibit influenza virus replication and pathogenesis of virus-induced disease. This novel therapeutic approach involves advanced cell-based antiviral strategies. In this review current advances in the anti-influenza therapy for both traditional virus-based antiviral strategies as well as for alternative cell-based antiviral strategies are described focusing on the last 10 years. Anti-influenza compounds are classified on the basis of their chemical structure with a special attention to describe their synthetic pathways and the corresponding structure activity relationships. 2009-12-31T23:00:00Z http://hdl.handle.net/2067/1823 Title: Borate minerals and RNA stability Authors: Cossetti, Cristina; Crestini, Claudia; Saladino, Raffaele; Di Mauro, Ernesto Abstract: The abiotic origin of genetic polymers faces two major problems: a prebiotically plausible polymn. mechanism and the maintenance of their polymd. state outside a cellular environment. The stabilizing action of borate on ribose having been reported, the authors have explored the possibility that borate minerals stabilize RNA. Borate itself does not stabilize RNA. The anal. of a large panel of minerals tested in various phys.-chem. conditions shows that in general no protection is exerted on the RNA backbone, with the interesting exception of ludwigite (Mg2Fe3+BO5). Stability is a fundamental property of nucleic polymers and borate is an abundant component of the planet, hence the prebiotic interest of this anal. Description: L'articolo è disponibile sul sito dell'editore: http://www.mdpi.com 2009-12-31T23:00:00Z http://hdl.handle.net/2067/1347 Title: A selective de-O-methylation of guaiacyl lignans to corresponding catechol derivatives by 2-iodoxybenzoic acid (IBX). The role of the catechol moiety on the toxicity of lignans Authors: Bernini, Roberta; Barontini, Maurizio; Mosesso, Pasquale; Pepe, Gaetano; Willfoer, Stefan M.; Sjoeholm, Rainer E.; Eklund, Patrick C.; Saladino, Raffaele Abstract: We report here the first selective de-O-methylation of a large panel of guaiacyl lignans to the corresponding catechol derivatives by using IBX as primary oxidant under green conditions (dimethyl carbonate–H2O solvent) through an in situ reduction procedure. The influence of the catechol moiety on the cytotoxicity and genotoxicity of new lignan derivatives has been investigated. The results obtained indicated that the presence of the catechol moiety sharply enhances the clastogenic potential (e.g. induction of chromosomal aberrations), the cytotoxicity and the modulation of cell cycle progression with respect to the parent compounds. Thus, despite the in vitro antioxidant activity usually described for catechol derivatives, our results show for the first time the generation of a clastogenic potential, highly indicative of a long-term genetic and cancer risk Description: L'articolo è disponibile sul sito dell'editore: http://www.rsc.org 2008-12-31T23:00:00Z http://hdl.handle.net/2067/1795 Title: An efficient and selective epoxidation of olefins with novel methyltrioxorhenium/(fluorous ponytailed) 2,2′-bipyridine catalysts Authors: Saladino, Raffaele; Ginnasi, Maria Cristina; Collalto, Daniela; Bernini, Roberta; Crestini, Claudia Abstract: Novel complexes between methyltrioxorhenium (MTO) and bis(fluorous- ponytailed) 2,2′bipyridines (bpy-Fn) were synthesized and used for the oxidation of alkenes with hydrogen peroxide under fluorous catalysis. High conversions and yields of the corresponding epoxides were obtained. Description: L'articolo è disponibile sul sito dell'editore: http://www.onlinelibrary.wiley.com 2009-12-31T23:00:00Z http://hdl.handle.net/2067/1797 Title: Oxidative strategies in lignin chemistry: A new environmental friendly approach for the functionalisation of lignin and lignocellulosic fibers Authors: Crestini, Claudia; Crucianelli, Marcello; Orlandi, Marco; Saladino, Raffaele Abstract: Novel processing methods and product concepts are required to extend the role of lignin for future biomass and biofuel applications in emerging platforms such as the biorefinery. The possible strategies of lignin valorisation are focused into two main directions, namely the selective functionalisation of the lignin polymer or in its oxidative depolymerization to get polyfunctional monomeric compounds. Here we report a panel of biocatalysis, organometallic catalysis, biomimetic catalysis and plasma oxidation processes developed by our research group for the activation of the environmental friendly oxidants oxygen and hydrogen peroxide in the oxidative functionalisation of lignin and lignin model compounds. Description: L'articolo è disponibile sul sito dell'editore: http://www.sciencedirect.com 2009-12-31T23:00:00Z http://hdl.handle.net/2067/1820 Title: Role of clays in the prebiotic synthesis of sugar derivatives from formamide Authors: Saladino, Raffaele; Neri, Veronica; Crestini, Claudia Abstract: We describe here the role of montmorillonite KSF in the prebiotic synthesis of amino sugar derivatives starting from a mixture of formamide and formaldehyde as simple chemical precursors. Since amino sugars are key intermediates in the synthesis of complex nucleic acid derivatives, this procedure opens a novel pathway for the formation of nucleosides under plausible primordial conditions Description: L'articolo é disponibile sul sito dell'editore: http://www.informaworld.com 2009-12-31T23:00:00Z http://hdl.handle.net/2067/1821 Title: The role of the formamide/zirconia system in the synthesis of nucleobases and biogenic carboxylic acid derivatives Authors: Saladino, Raffaele; Neri, Veronica; Crestini, Claudia; Costanzo, Giovanna; Graciotti, Michele; Di Mauro, Ernesto Abstract: We describe the one-pot synthesis of a large variety of nucleic acid bases and related compounds from formamide in the presence of zirconium minerals as catalysts. The major products observed are: purine, 2-hydroxy pyrimidine, 5-hydroxy pyrimidine, isocytosine, adenine, urea, and carbodiimide. The synthesis of low molecular weight amides and carboxylic acid derivatives (intermediates of extant metabolism) was also observed: glyoxylamide, glycolic-, lactic-, succinic-, oxalic-, fumaric-, and maleic acids. As the major problem in the origin of informational polymers is the instability of their precursors, we also investigated the effects of zirconia minerals on the stability of ribooligonucleotides in formamide and in water. The relevance of these findings with respect to the origin of informational polymers and primordial metabolism is discussed. Description: L'articolo é disponibile sul sito dell'editore: http://www.springerlink.com 2009-12-31T23:00:00Z http://hdl.handle.net/2067/1822 Title: Chitin and Chitosan anchored methyltrioxorhenium: an innovative approach for selective heterogeneous catalytic epoxidations of olefins Authors: Di Giuseppe, Andrea; Crucianelli, Marcello; Passacantando, Maurizio; Nisi, Stefano; Saladino, Raffaele Abstract: Novel complexes between methyltrioxorhenium (MTO) and natural polysaccharides like chitin and chitosan, or modified chitosan-bearing N-substituted acyl or alkyl pyridine moieties, were synthesized and used for the oxidation of alkenes, including acid-sensitive styrene derivatives, with urea hydrogen peroxide adduct (UHP) as primary oxidant. High conversions and yields of the corresponding epoxides were obtained. Silica-chitosan hybrid composites with increased surface area and mechanical properties were also prepared and used as MTO supports. A correlation on the role played by the different MTO-coordinating ligand sites of supports, on the experimental outcome of olefin catalytic oxidations, is discussed. Description: L'articolo è disponibile sul sito dell'editore: http://www.sciencedirect.com 2010-12-31T23:00:00Z