Navegando por Autor "Freitas, Rossimiriam Pereira de"
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Item Adsorption of Cu(II), Cd(II), and Pb(II) from aqueous single metal solutions by mercerized cellulose and mercerized sugarcane bagasse chemically modified with EDTA dianhydride (EDTAD).(2009) Karnitz Júnior, Osvaldo; Gurgel, Leandro Vinícius Alves; Freitas, Rossimiriam Pereira de; Gil, Laurent FrédéricThis work describes the preparation of new chelating materials derived from cellulose and sugarcane bagasse for adsorption of Cu2+, Cd2+, and Pb2+ ions from aqueous solutions. The first part involved the mercerization treatment of cellulose and sugarcane bagasse with NaOH 5 mol/L. Non- and mercerized cellulose and sugarcane bagasse were then reacted with ethylenediaminetetraacetic dianhydride (EDTAD) in order to prepare different chelating materials. These materials were characterized by mass percent gain, X-ray diffraction, FTIR, and elemental analysis. The second part consisted of evaluating the adsorption capacity of these modified materials for Cu2+, Cd2+, and Pb2+ ions from aqueous single metal solutions, whose concentration was determined by atomic absorption spectroscopy. These materials showed maximum adsorption capacities for Cu2+, Cd2+, and Pb2+ ions ranging from 38.8 to 92.6 mg/g, 87.7 to 149.0 mg/g, and 192.0 to 333.0 mg/g, respectively. The modified mercerized materials showed larger maximum adsorption capacities than modified non-mercerized materials.Item Adsorption of Cu(II), Cd(II), and Pb(II) from aqueous single metal solutions by sugarcane bagasse and mercerized sugarcane bagasse chemically modified with succinic anhydride.(2008) Gurgel, Leandro Vinícius Alves; Freitas, Rossimiriam Pereira de; Gil, Laurent FrédéricThis work describes the preparation of new chelating material from mercerized sugarcane bagasse. The first part treats the chemical modification of non-mercerized sugarcane bagasse (SCB) and twice-mercerized sugarcane bagasse (MMSCB) with succinic anhydride. Mass percent gains (mpg) and degrees of succinylation (DS) of succinylated non- and twice-mercerized sugarcane bagasse 1 (SCB 1 and MMSCB 1) were calculated. MMSCB 1 exhibited an increase in mpg and DS of 49.2% and 0.9 mmol/g in relation to SCB 1. SCB 2 and MMSCB 2 were obtained by treatment of MMSCB 1 and SCB 1 with bicarbonate solution to release the carboxylate functions and characterized by FTIR. The second part evaluates and compares the adsorption capacity of SCB 2 and MMSCB 2 for Cu2+, Cd2+ and Pb2+ ions in an aqueous single metal solution. Adsorption isotherms were developed using Langmuir model. MMSCB 2 exhibited an increase in Qmax for Cd2+ (43.6 mg/g) and Pb2+ (83.3 mg/g) in relation to SCB 2.Item Application of a new bifunctionalized chitosan derivative with zwitterionic characteristics for the adsorption of Cu2+, Co2+, Ni2+, and oxyanions of Cr6+ from aqueous solutions : kinetic and equilibrium aspects.(2016) Almeida, Francine Tatiane Rezende de; Ferreira, Bruno Christiano Silva; Moreira, Ana Luísa da Silva Lage; Freitas, Rossimiriam Pereira de; Gil, Laurent Frédéric; Gurgel, Leandro Vinícius AlvesThis study describes the synthesis of a new chitosan derivative (C2) with zwitterionic characteristics and its use for the removal of cationic species Cu2+, Co2+, and Ni2+ and anionic species of Cr6+ in a single aqueous solution. The new adsorbent was synthesized by quaternization of the amine group of chitosan and esterification of hydroxyl groups with EDTA dianhydride. These combined reactions gave both cationic and anionic characteristics to C2 with the release of quaternary ammonium groups and carboxylic groups. The capacity of C2 to adsorb Cu2+, Co2+, Ni2+, and oxyanions of Cr6+ was evaluated in a batch process with different contact times, pH values, and initial concentrations. Adsorption isotherms were best fitted to the Langmuir and Sips models. The maximum adsorption capacities (Qmax) of C2 for adsorption of Cu2+, Co2+, Ni2+, and Cr6+ were 0.698, 1.125, 0.725, and 1.910 mmol/g, respectively. The DadsG_ values were in the range from _20 to _28 kJ/mol. These values suggest a mixed mechanism controlling adsorption. Desorption studies using an aqueous solution consisting of 0.1 mol/L HNO3 were carried out. The reusability of the recovered C2 adsorbent after desorption was also evaluated.Item Application of a new carboxylate-functionalized sugarcane bagasse for adsorptive removal of crystal violet from aqueous solution : kinetic, equilibrium and thermodynamic studies.(2015) Ferreira, Bruno Christiano Silva; Teodoro, Filipe Simões; Mageste, Aparecida Barbosa; Gil, Laurent Frédéric; Freitas, Rossimiriam Pereira de; Gurgel, Leandro Vinícius AlvesA new carboxylate-functionalized sugarcane bagasse (SMA) was prepared via a solvent-free procedure involving esterification of sugarcane bagasse with Meldrum’s acid. The optimized conditions provided SMA with a percent weight gain of 86.0% and 4.69±0.20 mmol/g of carboxylic acid groups. SMA was characterized by FTIR, TGA, elemental analysis and SEM. Kinetic experiments showed that the amount of crystal violet adsorbed increased with increasing temperature and equilibrium was reached at 12 h. Adsorption kinetics followed a pseudo-second-order model. The Arrhenius and Eyring models were used to obtain the activation energy and changes in free energy, enthalpy, and entropy of activation for the adsorption process. The calculated activation energy (14.14 kJ/mol) suggested physical adsorption of CV onto SMA. The equilibrium data were well fitted to the Langmuir and Sips isotherms. Maximum adsorption capacity was 692.1 mg/g at 45 ◦C. Thermodynamic parameters such as changes in free energy, enthalpy and entropy were also determined.Item Chimeric protein−protein interface inhibitors allow efficient inhibition of type III secretion machinery and pseudomonas aeruginosa virulence.(2019) Ngo, Tuan Dung; Ple, Sophie; Thomas, Aline; Barette, Caroline; Fortuné, Antoine; Bouzidi, Younès; Fauvarque, Marie-Odile; Freitas, Rossimiriam Pereira de; Hilário, Flaviane Francisco; Attree, Ina; Wong, Yung-Sing; Faudry, EricPseudomonas aeruginosa (P. aeruginosa) is an opportunistic pathogen naturally resistant to many common antibiotics and acquires new resistance traits at an alarming pace. Targeting the bacterial virulence factors by an antivirulence strategy, therefore, represents a promising alternative approach besides antibiotic therapy. The Type III secretion system (T3SS) of P. aeruginosa is one of its main virulence factors. It consists of more than 20 proteins building a complex syringe-like machinery enabling the injection of toxin into host cells. Previous works showed that disrupting interactions between components of this machinery efficiently lowers the bacterial virulence. Using automated target-based screening of commercial and in-house libraries of small molecules, we identified compounds inhibiting the protein–protein interaction between PscE and PscG, the two cognate chaperones of the needle subunit PscF of P. aeruginosa T3SS. Two hits were selected and assembled using Split/Mix/Click chemistry to build larger hybrid analogues. Their efficacy and toxicity were evaluated using phenotypic analysis including automated microscopy and image analysis. Two nontoxic hybrid leads specifically inhibited the T3SS and reduced the ex vivo cytotoxicity of bacteria and their virulence in Galleria mellonella.Item Crossing of the cystic barriers of Toxoplasma gondii by the fluorescent coumarin tetra-cyclopeptide.(2021) Dard, Céline; Leforestier, Baptiste; Hilário, Flaviane Francisco; Traoré, Mohamed Dit Mady; Lespinasse, Marie-Ange; Pérès, Basile; Molina, Marie-Carmen; Freitas, Rossimiriam Pereira de; Milet, Anne; Maubon, Danièle; Wong, Yung-SingFR235222 is a natural tetra-cyclopeptide with a strong inhibition effect on histone deacety- lases, effective on mammalian cells as well as on intracellular apicomplexan parasites, such as Toxo- plasma gondii, in the tachyzoite and bradyzoite stages. This molecule is characterized by two parts: the zinc-binding group, responsible for the binding to the histone deacetylase, and the cyclic tetrapeptide moiety, which plays a crucial role in cell permeability. Recently, we have shown that the cyclic tetrapeptide coupled with a fluorescent diethyl-amino-coumarin was able to maintain properties of cellular penetration on human cells. Here, we show that this property can be extended to the crossing of the Toxoplasma gondii cystic cell wall and the cell membrane of the parasite in its bradyzoite form, while maintaining a high efficacy as a histone deacetylase inhibitor. The investigation by molecular modeling allows a better understanding of the penetration mechanism.Item Modeling mono- and multi-component adsorption of cobalt(II), copper(II), and nickel(II) metal ions from aqueous solution onto a new carboxylated sugarcane bagasse. Part I: Batch adsorption study.(2015) Ramos, Stela Nhandeyara do Carmo; Xavier, Amália Luísa Pedrosa; Teodoro, Filipe Simões; Carvalho, Megg Madonyk Cota Elias; Gonçalves, Fernanda Jorge; Gil, Laurent Frédéric; Freitas, Rossimiriam Pereira de; Gurgel, Leandro Vinícius AlvesA new carboxylated-functionalized sugarcane bagasse (STA) was prepared through the esterification of sugarcane bagasse with trimellitic anhydride. The optimized synthesis conditions yield STA with a percent weight gain of 73.9% and the number of carboxylic acid groups accounted for 3.78 mmol/g. STA was characterized by FTIR, elemental analysis, TGA, PZC, and SEM. Adsorption kinetics followed a pseudosecond- order model. The adsorption rate constant showed the following order: k2,Ni 2+ > k2,Cu 2+ > k2,Co 2+. Four mono- and multi-component isotherm models were used to model the adsorption systems. Monocomponent experimental data were fitted to Langmuir and Sips models; whereas, multicomponent data were fitted to modified extended Langmuir and P-factor models. The maximum adsorption capacities (Qmax,mono) obtained from the Langmuir model were 1.140, 1.197, and 1.563 mmol/g for Co2+, Cu2+, and Ni2+, respectively. The competitive studies demonstrated that the multicomponent adsorption capacity (Qmax,multi) was smaller than Qmax,mono, as a result of the interaction between the metal ions. Desorption studies showed that all metal ions could be fully desorbed from STA.Item Obtenção de um novo derivado carboxilado de celulose microcristalina : uma síntese fácil e sem solvente.(2017) Ferreira, Bruno Christiano Silva; Gil, Laurent Frédéric; Gurgel, Leandro Vinícius Alves; Freitas, Rossimiriam Pereira deO presente trabalho descreve a preparação de um novo derivado carboxilado de celulose microcristalina, usando como agente de esterificação o ácido de Meldrum (2,2-dimetil-1,3-dioxano-4,6-diona), sem utilização de solvente. O método produziu um novo material com alto grau de funcionalização. Condições otimizadas de síntese produziram celulose microcristalina modificada com ácido de Meldrum (MCCM) com um ganho de massa de 79,9 % e 4.21 mmol/g de funções carboxílicas introduzidas após 4 horas de reação usando uma proporção de celulose microcristalina (MCC) para ácido de Meldrum (MA) de 1:6. MCCM foi caracterizada com sucesso usando FTIR, Difração de Raio-X (DRX), análise termogravimétrica (TG) e Microscopia Eletrônica de Varredura (MEV).Item Síntese de um derivado bifuncionalizado inédito de quitosana para a remoção dos íons metálicos Cu2+ e CrO4 2- em solução aquosa.(2018) Moreira, Ana Luísa da Silva Lage; Novack, Kátia Monteiro; Gil, Laurent Frédéric; Gurgel, Leandro Vinícius Alves; Novack, Kátia Monteiro; Freitas, Rossimiriam Pereira de; Mageste, Aparecida Barbosa; Gil, Laurent Frédéric; Gurgel, Leandro Vinícius AlvesA contaminação da água tem atraído preocupação internacional nos últimos anos. Essa contaminação acontece por diferentes poluentes e nesse grupo de poluentes se encontram os metais pesados presentes em concentrações tóxicas nos sistemas aquosos. Por isso é importante procurar formas de tratar esses corpos d’água contaminados, e dentre as opções, se encontra o uso de biossorventes como a quitosana, biopolímero de fácil acesso e que pode ser modificada para aumentar sua capacidade de adsorção. Nesse projeto a quitosana foi usada na preparação de um novo material bifuncionalizado. Essas modificações foram realizadas com o intuito de produzir um material capaz de remover cátions e oxiânions de metais pesados. Para essa modificação reagiu-se a quitosana com 2-piridinacarboxialdeído de modo a obter uma função capaz de quelar cátions metálicos em valores de pH básicos e em valores de pH ácidos atrair oxiânions por atração eletrostática. Introduziu-se também funções carboxilato através de reação com dianidrido de EDTA possibilitando adsorver cátions metálicos quando o material se encontra desprotonado, gerando o adsorvente Q4. Para a reação com dianidrido de EDTA foi realizado um planejamento estatístico 2³, com repetição do ponto central a fim de encontrar a melhor condição reacional dentre os parâmetros avaliados. As variáveis analisadas foram tempo reacional, equivalente em massa de dianidrido de EDTA e temperatura e a resposta de interesse foi massa final obtida. O material adsorvente inédito bifuncionalizado Q4 foi caracterizado por FTIR, TGA, 13C RMN, análise elementar e MEV e foi também avaliado quanto à sua capacidade de adsorção em função do pH, do tempo de contato (cinética) e da concentração inicial dos metais (isoterma). As capacidades máximas de adsorção (Qmax) de Q4 para Cu2+ e Cr6+ foram de 2,33mmol/g e 3,66mmol/g, respectivamente. A capacidade de readsorção do adsorvente Q4 regenerado também foi avaliada (2,20 mmol/g para Cu2+ e 1,54 mmol/g para Cr6+).Item Synthesis of an uncharged tetra-cyclopeptide acting as a transmembrane carrier : enhanced cellular and nuclear uptake.(2017) Hilário, Flaviane Francisco; Traoré, Mohamed Dit Mady; Zwick, Vincent; Berry, Laurence; Pires, Claudia A. Simões; Cuendet, Muriel; Fantozzi, Nicolas; Freitas, Rossimiriam Pereira de; Maynadier, Marjorie; Wein, Sharon; Vial, Henri; Wong, Yung-SingA small uncharged cyclopeptide scaffold inspired by a natural product and designed to undergo postfunctionalizations was used as a new transmembrane vector. A bioactive and fluorescent triazole aminocoumarin was bound to this carrier to facilitate its moving across cell and subcellular membranes, and this led to an increase in its cell toxicity.Item Synthesis, cytotoxic activity, and mode of action of new Santacruzamate A analogs.(2018) Andrade, Silmara Nunes; Evangelista, Fernanda Cristina Gontijo; Seckler, Diego Eduardo Lima; Marques, Deisielly Ribeiro; Freitas, Tulio Resende; Nunes, Renata Rachide; Oliveira, Júlia Teixeira de; Ribeiro, Rosy Iara Maciel de Azambuja; Santos, Helio Batista dos; Thomé, Ralph Gruppi; Taranto, Alex Gutterres; Santos, Fabio Vieira dos; Viana, Gustavo Henrique Ribeiro; Freitas, Rossimiriam Pereira de; Humberto, Jorge Luiz; Sabino, Adriano de PaulaBreast and ovarian cancer are the most common cancers in women. Available cancer treatments, in general, have limited efficacy and frequent, undesirable side effects. Recently, scientists have focused on searching for new epigenetic modulators such as inhibitors of DNA methyltransferases and histone deacetylases (HDACs), with novel properties and selectivity. We report the synthesis of seven new analogs of Santacruzamate A. Molecular modeling showed that compounds 3–9 presented the best binding energies (kcal/mol) against HDAC4 compared to that of crystallographic ligand. The compounds were evaluated against MCF-7 and MDA-MB-231 (breast cancer), TOV-21G (ovarian adenocarcinoma), and WI-26VA4 (non-tumor lung fibroblasts) cells. Compound 5, the most potent and selective of the series, exhibited remarkably enhanced anticancer potency, with IC50 values for the tumor cells of 24.3–44.93 μM, compared with that of etoposide (12–18.57 μM) and doxorubicin (2.1–4.37 μM). Further investigation showed that compound 5 could promote DNA damage, increase the activity of caspases-3 and -9, and upregulate mRNA levels of p21, TP53, and BAK, suggesting apoptotic cell death of the tumor cells via the intrinsic pathway. This study demonstrated that synthetic analogs of santacruzamate A with zinc-linked groups are effective for improving both HDAC inhibition and antitumor activity.