RESUMO
Pentose dehydration and direct transformation of xylan into furfural were performed in a water-cyclopentyl methyl ether (CPME) biphasic system under microwave irradiation. Heated up between 170 and 190 °C in the presence of Nafion NR50 and NaCl, d-xylose, l-arabinose and xylan gave furfural with maximum yields of 80%, 42% and 55%, respectively. The influence of temperature and reaction time on the reaction kinetics was discussed. This study was also completed by the survey of different reactant ratios, such as organic layer-water or catalyst-inorganic salt ratios. The exchange between proton and cation induced by an excess of NaCl was monitored, and a synergetic effect between the remaining protons and the released HCl was also discovered.
Assuntos
Furaldeído/síntese química , Xilanos/química , Xilose/química , Catálise , Polímeros de Fluorcarboneto/química , Furaldeído/química , Temperatura Alta , Micro-Ondas , Estrutura Molecular , Cloreto de Sódio/química , Água/químicaRESUMO
Cationic nucleoside lipids (CNLs) derived from 5-nitroindole and 4-nitroimidazole bases were prepared from d-ribose by using a straightforward chemical synthesis. TEM experiments indicate that these amphiphilic molecules self-assemble to form supramolecular organizations in aqueous solutions. Electrophoresis and standard ethidium bromide (EB) fluorescence displacement assay shows that CNLs are able to bind siRNA. We demonstrated that both the nature of the universal bases and the stereochemistry of the anomeric position (alpha, beta) have an impact on the CNLs-siRNA complex formation. Correlations among chemical structure, stereochemistry, siRNA knockdown effect, and binding affinities for all the compounds were shown and analyzed with a simple molecular modeling study. The best binding affinities for siRNA were found for the beta anomer of the 5-nitroindole CNL which exhibits protein knockdown activity similar to the standard siPORT NeoFX positive control. It is noteworthy that no significant cytotoxicity at the tested concentration was observed for the novel CNLs.
Assuntos
Lipídeos/química , Nucleosídeos/química , RNA Interferente Pequeno/genética , Ribose/química , Transfecção/métodos , Sítios de Ligação , Cátions/química , Eletroforese , Etídio/química , Etídio/metabolismo , Indóis/química , Microscopia Eletrônica de Transmissão , Modelos Moleculares , Nitroimidazóis/química , RNA Interferente Pequeno/química , Espectrometria de FluorescênciaRESUMO
Cationic nucleoside lipids based on a 3-nitropyrrole universal base were prepared from D-ribose using a straightforward chemical synthesis. Several studies including DLS, TEM, and ethidium bromide (EthBr) assay demonstrated that these amphiphilic molecules form supramolecular organizations of nanometer size in aqueous solutions and are able to bind nucleic acids. siRNA knockdown experiments were performed with these nucleolipids, and we observed protein knockdown activity similar to the siPORT NeoFX positive control. No significant cytotoxicity was found.