Navegando por Autor "Oliveira, Guilherme Roberto de"
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- ItemAtividade antibacteriana e quantificação de cloridrato de polihexametileno biguanida (P.H.M.B) em tecidos musculares e vísceras de frangos(Antônio Henrique Garcia, 1997-06) Mesquita, Albenones José de; Lage, Moacir Evandro; Oliveira, Guilherme Roberto de; Prado, Cristiano SalesTriais were carried 0111 in order to check 0111 the viability of polyhexamethylene bignanide hydrochloride in the control of pathogenic and degenerating bacteria in can:ass of chicken, as well as a spectrophotometric monitoring of the residual content of this polymer in the carcasses and víscera of chicken quenched with biguanid. The sanitizing power of this substance was high, although the previo11s analysis point out to the inefficacy of the residual monitoring method, due to the action of interferings.
- ItemGenotoxicity and cytotoxicity evaluation of the neolignan analogue 2-(4-nitrophenoxy)-1phenylethanone and its protective effect against DNA damage(2015-11) Hanusch, Alex Lucas; Oliveira, Guilherme Roberto de; Sabóia-Morais, Simone Maria Teixeira de; Machado, Rafael Cosme; Anjos, Murilo Machado dos; Lee, Chen ChenNeolignans are secondary metabolites found in various groups of Angiosperms. They belong to a class of natural compounds with great diversity of chemical structures and pharmacological activities. These compounds are formed by linking two phenylpropanoid units. Several compounds that have ability to prevent genetic damage have been isolated from plants, and can be used to prevent or delay the development of tumor cells. Genetic toxicology evaluation is widely used in risk assessment of new drugs in preclinical screening tests. In this study, we evaluated the genotoxicity and cytotoxicity of the neolignan analogue 2-(4- nitrophenoxy)-1-phenylethanone (4NF) and its protective effect against DNA damage using the mouse bone marrow micronucleus test and the comet assay in mouse peripheral blood. Our results showed that this neolignan analogue had no genotoxic activity and was able to reduce induced damage both in mouse bone marrow and peripheral blood. Although the neolignan analogue 4NF was cytotoxic, it reduced cyclophosphamide-induced cytotoxicity. In conclusion, it showed no genotoxic action, but exhibited cytotoxic, antigenotoxic, and anticytotoxic activities.
- ItemInsights into chalcone analogues with potential as antioxidant additives in diesel–biodiesel blends(2022) Borges, Igor Dalarmelino; Faria, Eduardo Coelho da Mata; Custodio, Jean Marcos Ferreira; Duarte, Vitor Santos; Fernandes, Fernanda de Sousa; Alonso, Christian Gonçalves; Silva, Valter Henrique Carvalho; Oliveira, Guilherme Roberto de; Napolitano, Hamilton BarbosaBiodiesel production is one of the promising strategies to reduce diesel consumption and an important contribution to climate change. However, biodiesel stability remains a challenging problem in biofuel use in the global energy matrix. In this context, organic additives have been investigated to minimize these problems and reduce harmful emissions to comply with fuel requirement standards. In this study, we discuss a comprehensive structural description, a behavior of B15 [85% volume of diesel and 15% volume of biodiesel (B100)] stability in the presence of antioxidants (chalcone analogues), and a theoretical calculation to pave the way for clarifying and expanding the potential of title compounds as an antioxidant additive for diesel–biodiesel blends. Finally, a systematic description of the oxidation stability was undertaken using a specialized machine learning computational pySIRC platform.
- ItemInsights on sustainable fuels: a new benzimidazole derivative with potential as a diesel-biodiesel blend additive(2023) Duarte, Vitor Santos; Naves, Raquel Ferreira; Bortoluzzi, Adailton João; Faria, Eduardo Coelho da Mata; Magalhães, Aline da Silva; Mori, Vânia; Alonso, Christian Gonçalves; Oliveira, Guilherme Roberto de; Napolitano, Hamilton BarbosaBiodiesel is an important fuel in the energy industry with recurrent durability and stability problems. The use of molecular-based technologies to preserve the physicochemical properties of diesel-biodiesel blend is a promising path on additive studies. To minimize oxidative stability problems and get insights into the additive structural features, we evaluated a new benzimidazole derivative as a potential additive for diesel-biodiesel blends. In the study, an extensive structural description and supramolecular topological analysis, besides theoretical calculations to understand specific physicochemical properties related to oxidative stability when added to biofuel, were carried out. Also, the synthesis of the title compound in the presence of graphite oxide shows a sustainable synthetic route, and the supramolecular arrangement has only C–H···O and C–H···π interactions that are related to antibacterial and antioxidant activity. The new benzimidazole derivative structure has two alkoxy groups in the para position of the aromatic ring acting as electron-donating substituents – desirable conformations for antioxidant activity. The energy of 640.99 kJ/mol in the Frontier Molecular Orbitals indicates high kinetic stability and the oxidative stability in the diesel-biodiesel blend (B20) was 26.3 h (better than commercial additives). The obtained results indicate the potential of benzimidazole derivative as a diesel-biodiesel blend additive.
- ItemModulating effect of a hydroxychalcone and a novel coumarin–chalcone hybrid against mitomycin-induced genotoxicity in somatic cells of Drosophila melanogaster(2022) Véras, Jefferson Hollanda; Vale, Camila Regina do; Lima, Débora Cristina da Silva; Anjos, Murilo Machado dos; Valeze, Aline Bernardes; Moraes Filho, Aroldo Vieira de; Silva, Carolina Ribeiro e; Oliveira, Guilherme Roberto de; Noda Pérez, Caridad; Lee, Chen ChenChalcones are aromatic compounds found in plants or obtained by synthetic methods. These compounds and their derivatives have been proven to be responsible for a variety of pharmacological properties, including anti-inflammatory and anticancer activities. A second interesting class of compound are coumarins which comprises a large class of molecules derived from phenolic compounds found mainly in plants, exhibiting multiple biological activities such as antioxidant and anti-tumoral properties. Due to the relevance of these compounds, this study aimed to investigate the genotoxic/antigenotoxic effects of the chalcone (E)-1-(2-hydroxyphenyl)-3-(4-methylphenyl)-prop-2-en-1-one (2HMC) and the coumarin–chalcone hybrid [7-methoxy-3-(E)-3-(3,4,5-trimethoxyphenyl)acryloyl-2H-cromen-2-one] (4-MET) using the somatic mutation and recombination test (SMART) in Drosophila melanogaster. To assess the mutagenic and recombinogenic activities, larvae derived from standard and high bioactivation crosses were treated with different concentrations of 2HMC (10, 50, 100 and 400 µg/mL) or 4-MET (5, 50, 100 and 400 µg/mL) for 48 h. Dimethylsulfoxide (DMSO, 0.5%) was the negative control group. The anti-recombinogenic and antimutagenic activities were assessed using larvae from both crosses co-treated with the same concentrations of 2HMC or 4-MET and mitomycin C (MMC, 0.05 mM). SMART revealed no mutagenic or recombinogenic effects since no significant increase of any category of mutant spots was observed (p > 0.05). However, both compounds reduced the frequency of all spots induced by MMC showing antimutagenic and anti-recombinogenic activities in D. melanogaster cells from both crosses. We suggest that the antimutagenic and anti-recombinogenic activities observed in our study may have been a result of the antioxidant activity of 2HMC and 4-MET.
- ItemNb2O5 supported catalysts for cross-coupling reactions(2020) Souza, Guilherme Botelho Meireles de; Ribeiro, Thiago Soares Silva; Mourão, Lucas Clementino; Pereira, Mariana Bisinotto; Leles, Maria Inês Goncalves; Liao, Luciano Morais; Oliveira, Guilherme Roberto de; Alonso, Christian GonçalvesPalladium and nickel supported on Nb2O5 were synthesized via wet impregnation method and tested for the Suzuki-Miyaura reaction. The catalysts were characterized by X-ray fluorescence, textural analysis, scanning and transmission electron microscopy, thermogravimetry/differential thermal analysis and X-ray diffraction. Palladium catalyst resulted in high isolated yields (91%). Satisfactory yields (48%) were achieved employing the nickel catalyst. Hot filtration experiments were performed to evaluate the reaction heterogeneity. The catalysts were submitted to consecutive reactions runs to assess recyclability. Deactivation was attributed to catalyst loss by filtration between cycles, minor leaching of the active phase and poisoning by inorganic species.
- ItemA new halogen-chalcone with potential for application in biofuels(2020) Faria, Eduardo Coelho da Mata; Duarte, Vitor Santos; Silva, Aline Magalhães da; Fernandes, Fernanda de Sousa; Oliveira, Guilherme Roberto de; Napolitano, Hamilton BarbosaFossil fuels, which represent an important villain for the terrestrial ecosystem, are non-renewable sources of energy, which prompt many discussions about how long petroleum will remain available for use. As an alternative, new energy sources have been explored, including biofuels, such as biodiesel and ethanol. However, their use can raise some problems, such as lower storage stability associated with poor oxidation stability and lower energy availability, which affect consumption, emissions, and energy efficiency. In this context, a comprehensive study with structural description, theoretical calculations, and calorific power test was performed for a new halogen chalcone 4-(4-chlorophenyl)-1-[4-(2-oxo-2-phenylethoxy)phenyl]butan-2-one to understand its supramolecular arrangement and physicochemical properties. The structural description was carried out by X-ray diffraction with the contribution of Hirshfeld surfaces. The theoretical calculations were carried out using density functional theory with the contribution of calorific power determined by a calorimetric pump. All observed results characterize the new chalcone as a potential additive for biofuels.
- ItemRealidade do ensino de química no estado de Goiás: uma discussão a partir do desempenho dos alunos no processo seletivo 2011/1 da Universidade Estadual de Goiás(2012) Oliveira, Guilherme Roberto de; Ramos, Rogério Daniel Pereira; Hernández Fernández, HermíniaThis article discusses the main problems of chemistry teaching in public schools of the State of Goiás Through of core data selection from the State University of Goiás, a reflection about practice of chemistry teachers in high school becomes urgent. As reference for this study highlights the low yield in chemical tests on students enrolled in regular selection process 2010/1. Curriculum proposals from the MEC and SEDUC / GO underlie this study proposes methodological suggestions to teachers of chemistry so that they approach their students that what UEG charges on their college entrance exams.
- ItemSulfonated carbons from agro-industrial residues: simple and efficient catalysts for the Biginelli reaction(2022) Nascimento, Letícia Gomes do; Dias, Isabela Milhomem; Souza, Guilherme Botelho Meireles de; Mourão, Lucas Clementino; Liao, Luciano Morais; Viana, Julio Cezar Vieira; Liao, Luciano Morais; Oliveira, Guilherme Roberto de; Alonso, Christian GonçalvesThe Biginelli reaction is a one-pot acid-catalyzed cyclocondensation of an aromatic aldehyde, urea, and ethyl acetoacetate to synthesize dihydropyrimidinones (DHPMs). DHPMs are extremely important due to their wide-ranging pharmacological activities, and, for this reason, the Biginelli reaction has been at the forefront of investigations by various research groups. Here, we report the production of sulfonated carbons from agro-industrial wastes (rice husk and tomato bagasse) applied as an inexpensive and efficient heterogeneous catalyst for the synthesis of DHPMs. Catalysts were easily prepared by carbonization using sulfuric acid at 200 °C for 6 hours. The coal surface was characterized by N2 adsorption–desorption isotherms at −196 °C, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and textural analysis. Infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), and Raman analysis proved the sulphonation of catalysts. In addition, other complementary analyses were also carried out, such as elemental analysis of the contents of carbon, nitrogen, oxygen, and sulphur. Then, exploratory catalytic tests were carried out to define the optimal reaction conditions. For this purpose, the effects of different solvents, reaction temperatures, molar ratios of the reactants, and catalyst loads were investigated. The best results were achieved using the catalyst prepared from rice husk (CRH). A yield of 92% of DHPMs was achieved in a short reaction time under solvent-free conditions. Moreover, the catalyst was recovered and reused without a significant decrease in the yield. These findings show that the agro-industrial wastes can be explored to find novel and potential catalysts.
- ItemTreatment of hormones in wastewater from the pharmaceutical industry by continuous flow supercritical water technology(2021) Mourão, Lucas Clementino; Souza, Guilherme Botelho Meireles de; Dias, Isabela Milhomem; Andrade, Laiane Alves de; Souza, Paula Letícia de Melo; Cardozo Filho, Lúcio; Oliveira, Guilherme Roberto de; Oliveira, Sérgio Botelho de; Alonso, Christian GonçalvesHormones are bioactive, ubiquitous, and persistent organic molecules that demand effective treatment when released in the environment. However, most conventional treatments are inefficient or not suitable for large-scale applications. This study describes the use of supercritical water (SCW) technology in the degradation of hormones in wastewater from the pharmaceutical industry. Initially, the treatment was developed with synthetic wastewater (SW) containing hormone prepared from commercial desogestrel pills and, later, with real industrial wastewater (IW). All the experimental tests were conducted in a continuous flow reactor in the absence of catalysts. Both liquid and gas phases generated during the process were analyzed by instrumental techniques. The liquid phase was characterized by total organic carbon (TOC), chemical oxygen demand (COD), high-performance liquid chromatography (HPLC), and phytotoxicity assays. The gas phase was characterized by gas chromatography (GC). TOC reductions of SW and IW samples, both treated at 700 °C and feed flow rate of 10 mL min−1 were 87.2% and 88.4%, respectively. Phytotoxicity assays indicated a significant reduction in the toxicity of the IW treated at 700 °C. Thus, considering the gas production, especially hydrogen, and the high toxicity mitigation, the IW treatment via SCW is quite promising.