Doutorado em Química
URI Permanente para esta coleção
Nível: início
Ano de início: 2014
Conceito atual na CAPES: 5
Ato normativo: Homologação da 85ª Reunião do CTC-ES, Parecer CNE/CES nº 163/2005.
Processo nº 23001.000081/2005-56 do Ministério da Educação.
Publicado no DOU 28/07/2005, seção 1, página 11)
Periodicidade de seleção: Anual
Área(s) de concentração: Química
Url do curso: https://quimica.vitoria.ufes.br/pt-br/pos-graduacao/PPGQ/detalhes-do-curso?id=956/a>
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Navegando Doutorado em Química por Autor "Cunha Neto, Álvaro"
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- ItemAlcaloides dos bulbos das espécies Griffinia gardneriana (Herb.) Ravenna e Habranthus itaobinus Ravenna (amaryllidaceae): perfil químico e propriedades citotóxicas e genotóxicas(Universidade Federal do Espírito Santo, 2018-08-23) Cole, Eduardo Roberto; Borges, Warley de Souza; Lacerda Junior, Valdemar; Endringer, Denise Coutinho; Santos, Reginaldo Bezerra dos; Kuster, Ricardo Machado; Cunha Neto, ÁlvaroThe Amaryllidaceae family is widely distributed throughout the world, being considered one of the 20 most important families among which they present alkaloids in their composition, exhibiting antiviral, antimalarial, anticancer and anticholinesterase activities, among others. This work aims to perform a chemical study on alkaloids of Griffinia gardneriana and Habranthus itaobinus bulbs, belonging to this family, to evaluate its cytotoxic and genotoxic properties and the role of caspase-3 as a molecular mediator of apoptosis induced by these compounds. Fractions enriched in alkaloids obtained from G. gardneriana and H. itaobinus bulbs were initially subjected to gas chromatography coupled to mass spectrometry (GC-MS) and then fractionated by different chromatographic techniques, such as molecular exclusion chromatography, column chromatography and preparative thin layer chromatography. The isolation and identification of the alkaloids was done by means of high performance liquid chromatography and mono- and bidimensional nuclear magnetic resonance, in addition to circular dichroism. Studies were carried out to evaluate the cytotoxicity of the enriched fractions by the MTT method using the OVCAR-3, J774 and L929 cell lines. In addition, the in vitro cytotoxicity and genotoxicity of the alkaloids isolated (through the MTT assay and micronucleus test) using tumoral (HepG2, MCF- 7, A549) and normal (L929, CHO-1-15) cell lines. In parallel, a study was developed to evaluate the correlation of the results obtained in the cytotoxicity assays by MTT and cytometry by image analysis. Molecular docking studies were performed to evaluate the free binding energies between the alkaloids isolated with the caspase-3 protein, described in the literature as the probable site of action of these compounds, also being calculated the theoretical inhibition constant, Ki. The GC-MS result of the enriched fractions evidenced the presence of only one alkaloid in G. gardneriana and five in H. itaobinus. Seven alkaloids of Amaryllidaceae, belonging to different type skeletons, all of them already well characterized in the literature, are some common ones to the two species (trisphaeridine and pretazettine), whereas others present only in G. gardneriana (lycorine and sanguinine) or in H. itaobinus (tazettine, 11- hydroxyvitattine and 2-a-7-dimethoxyhomolycorine). All enriched fractions showed cytotoxic action in the tested methods, but for the alkaloids isolated 11-hydroxyvitattine and 2-a-7-dimethoxyhomocolycorine were not cytotoxic, whereas tazettine, trisphaeridine and sanguinine presented activity only against the fibroblastic lineage. Lycorine and pretazettine were 10 to 30 times more cytotoxic than the other alkaloids, being active also for the cancerous lines, exhibiting time-dependent and concentration action, besides being genotoxic and able to promote the apoptosis via caspase-3. This result corroborates the data obtained in the docking studies in which these two compounds were among those with the highest binding affinity values.
- ItemDeterminação de propriedade físico-químicas de biodiesel e blendas por RMN de baixo campo e calibração multivariada(Universidade Federal do Espírito Santo, 2018-11-06) Constantino, André Fazolo; Lacerda Junior, Valdemar; Consalter, Daniel Martelozo; Santos, Reginaldo Bezerra dos; Cunha Neto, Álvaro; Barbosa, Lúcio LeonelBecause the methods specified by regulatory agencies for the determination of the physicochemical properties of biodiesel can be laborious and expensive, the development of alternative methodologies represents a major breakthrough. Thus, low-field nuclear magnetic resonance (NMR) is an advantageous option because it is nondestructive and reduces the cost and time consumption. In this study, the partial least squares (PLS) regression method was used to create models that correlated the decay curves of the Carr–Purcell–Meiboom–Gill (CPMG) signal, Continuous Wave Free Precession (CWFPx-x) orCarr–Purcell Continuous Wave Free Precession (CP-CWFPx-x), obtained fromlow-field NMR equipments(2.2 MHz and 15.0 MHz for 1H), with the kinematic viscosity, specific mass,refractive index and iodine value of biodiesel and their blends. Seventeen oilseeds diversified between edible and non-edible oils were utilized to synthesizethe biodiesel and producebinary blends.Separately, multivariate calibration models were created only with pure biodiesel and blends withcastor bean because these samples showed different tendencies from the others. The best values of root mean square error of prediction (RMSEP) for the kinematic viscosity, specific mass and refractive index were equal to 0.1 mm2/s, 1.9 kg/m3, 0.002 and 15.5 g I2/100 g of sample,respectively, for samples of biodiesel and blends without castor bean and 0.3mm2/s, 1.3kg/m3,0.0003 and 1.9 g I2/100 g of samplefor samples of biodiesel and blends with castor bean. The results reveal that the developed models are very satisfactory to predict the quality parameters of biodiesel and blendswith fairly good efficacy, withthe models created withCPMG andCP-CWFPx-xdata being stood out to those constructedwith CWFPx-xdata. The physicochemical properties were also correlated with the decay curves of seed and oil samples, with the aim of predicting the quality of biodiesel from the analysis of its raw materials. However,the resultswere not very promising, sincethe correlations betweenmeasured physicochemical properties by American Society for Testing and Materials (ASTM) methods and its predicted values from the constructed PLS models resulted in very low coefficients of determination (R2)
- ItemEspectrometria de massas ambiente e tandem na quantificação de drogas de abuso(Universidade Federal do Espírito Santo, 2018-09-10) Santos, Heloa; Romão, Wanderson; Cunha Neto, Álvaro; Borges, Warley de Souza; Vaz, Boniek Gontijo; França, Hildegardo SeibertMass spectrometry (MS) is a powerful tool because has high resolution and specificity for molecules chemical characterization. Initially, paper chromatography was developed using Dragendorff reagent and paper spray ionization mass spectrometry (PS-MS) for quantification. Then, polymers with electrical conductivity (PC) were studied because they are promising in high voltage applied in PS-MS and charging drops formation. Furthermore, PC-coated paper surface can be determinant for analyzes of various analytes, such as: avermectins, bupropion and its metabolites, anesthetics, anxiolytics, hormones, meloxicam, adulterants and drugs of abuse. The emergence of new psychoactive substances (NPS) is worldwide and alarming. Considering this growing market for NPS synthesis, the last part of this study presents a simple direct analysis in real time (DART) method. In Chapter 2, The method presented linearity greater than 0.98 and LODs of 6.51 ?g/mL, 13.53 ?g/mL and 0.35 mg/mL for Cocaína, levamisole and Lidocaína, respectively. Ten samples were quantified by PS(+)-MS and there was not statistically significant difference between PS(+)-MS and gas chromatography with flame ionization detector (GC-FID) at a significance level of 5 %. In Chapter 3, Polypyrrole (PPy), Polyaniline (PAni) or both polymers [Poly (Py-co-Ani)] were synthetized on paper by in situ polymerization. All the analytes were tested by PS (+)-FT-ICR and, in most cases, coated papers showed a higher absolute intensity signal compared to conventional chromatographic paper. The [Poly (Py-co-Ani)] paper showed better results and the linearity of the response was evaluated in Orbitrap (r2> 0.9851). The [Poly (Py-co-Ani)] paper was subjected to the reuse test and, compared to the traditional chromatographic paper, its results are promising for qualitative and quantitative PS-MS analysis. In Chapter 4, preliminary screening with DART-MS accelerates the detection process for 25 compounds among the most prominent classes of NPS, including synthetic cannabinoids and cathinone derivatives. Methanolic extracts were studied by DART(+)-MS/MS and it was efficient for rapid screening and detection of NPS in oral fluid and the herbal material (Turnera diffusa). LC-MS was able to generate MS/MS spectra with adequate linearity and sensitivity. The method was fully validated in the range of 0.01 to 100 ppb. Preliminary result of proposed off-line SPE protocol showed acceptable recoveries for the majority of drugs. Quality control samples were used during the method validation process, and all analytes showed RSD below 20 %
- ItemEspectrometria de massas de alta resolução acoplada a espectrometria mobilidade iônica para análise de matrizes complexas(Universidade Federal do Espírito Santo, 2018-08-16) Tose, Lilian Valadares; Romão, Wanderson; Cunha Neto, Álvaro; Kuster, Ricardo Machado; Aquije, Gloria Maria de Farias Viégas; Lima, Francisco Alberto FernandezMass spectrometry (MS) is a technique able to ionize simple molecules until complex structures, performing efficiently and dynamically with a wide application using high sensitivity and speed of analysis. Although MS hasconsiderable interest in the scientific society, the application of new technologies in the field of complex matrix analysis still is little explored.Inanalyzes of crude oil, paraffin and condensed aromatic standards, the atmospheric solids analysis probe mass spectrometry (ASAP-MS) is a powerful ionization sourceforcharacterization of samples in original form. Initially, two methodologies were used to determine the chemical composition of the samples: (1) using a temperature gradient ranging from 150 to 600 °C at a heating rate of 150 °C.min-1(parafina) or 50 °C.min-1; (2) with a constant temperaturearound350 °C. ASAP(+)-MS ionized crude oil and paraffin, showing a typical petroleum profile in the range of m/z200 -1400 for both samples. This performancecould relateASAP sourceto detection of compounds of high molecular weight (> 1000 Da). In addition, the AC standardswere identifiedin two ionicforms: radicals, [M]+•and protonated cations, [M+H]+, with minimal fragmentation. Therefore, ASAP was efficient for accessing the chemical composition of polar and non-polar compounds.Analysis of the Cannabis sativaL. plant, were doing by ultra-high performance liquid chromatography coupled to travelingwave ionic mass spectrometry (UPLC-TWIMS MS) using electrospray ionization source in both modes, ESI (±). Hashish, marijuana, and parts of the plant Cannabis sativaL. (flower and leaf) were analyzed. Isomeric compounds were identified inacomplex mixture of cannabinoids, mainly ?9-THC, cannabidiol (CBN-C5and Mw= 310 Da), ?9-tetrahydrocannabinolic acid A and B (?9-THCA-C5A/B and Mw= 358 Da) and their isomers. Analizes by ESI-TWIMSMS were identified three isomers, m/z315/313, 311, and 357, while a high selectivity was observedin UPLC-ESI-TOF MS data, identifying more thanfour isomeric compounds in the single ion acquisition mode (SIM).In other study, we evaluated the use of a high resolution mobility analyzer coupled to ultra high resolution mass spectrometry for molecular characterization of dissolved organic matter. The main goal wastovalidate the reproducibility of trapped ion mobility spectrometry (TIMS), the range of applicability and possible challenges during routine analysis.TIMS coupledto TOF MS and FT-ICR MS showed similar 18performance and high reproducibility. For the analysis of complex mixtures, both platforms were able to aquiriedthe main characteristics. However, the increase ofchemical complexity at nominal mass level (m/z> 300-350), only TIMS-FT-ICR MS was able to solve the compositional tendencies of lower Mass spectrometry (MS) is a technique able to ionize simple molecules until complex structures, performing efficiently and dynamically with a wide application using high sensitivity and speed of analysis. Although MS hasconsiderable interest in the scientific society, the application of new technologies in the field of complex matrix analysis still is little explored.Inanalyzes of crude oil, paraffin and condensed aromatic standards, the atmospheric solids analysis probe mass spectrometry (ASAP-MS) is a powerful ionization sourceforcharacterization of samples in original form. Initially, two methodologies were used to determine the chemical composition of the samples: (1) using a temperature gradient ranging from 150 to 600 °C at a heating rate of 150 °C.min-1(parafina) or 50 °C.min-1; (2) with a constant temperaturearound350 °C. ASAP(+)-MS ionized crude oil and paraffin, showing a typical petroleum profile in the range of m/z200 -1400 for both samples. This performancecould relateASAP sourceto detection of compounds of high molecular weight (> 1000 Da). In addition, the AC standardswere identifiedin two ionicforms: radicals, [M]+•and protonated cations, [M+H]+, with minimal fragmentation. Therefore, ASAP was efficient for accessing the chemical composition of polar and non-polar compounds.Analysis of the Cannabis sativaL. plant, were doing by ultra-high performance liquid chromatography coupled to travelingwave ionic mass spectrometry (UPLC-TWIMS MS) using electrospray ionization source in both modes, ESI (±). Hashish, marijuana, and parts of the plant Cannabis sativaL. (flower and leaf) were analyzed. Isomeric compounds were identified inacomplex mixture of cannabinoids, mainly ?9-THC, cannabidiol (CBN-C5and Mw= 310 Da), ?9-tetrahydrocannabinolic acid A and B (?9-THCA-C5A/B and Mw= 358 Da) and their isomers. Analizes by ESI-TWIMSMS were identified three isomers, m/z315/313, 311, and 357, while a high selectivity was observedin UPLC-ESI-TOF MS data, identifying more thanfour isomeric compounds in the single ion acquisition mode (SIM).In other study, we evaluated the use of a high resolution mobility analyzer coupled to ultra high resolution mass spectrometry for molecular characterization of dissolved organic matter. The main goal wastovalidate the reproducibility of trapped ion mobility spectrometry (TIMS), the range of applicability and possible challenges during routine analysis.TIMS coupledto TOF MS and FT-ICR MS showed similar 18performance and high reproducibility. For the analysis of complex mixtures, both platforms were able to aquiriedthe main characteristics. However, the increase ofchemical complexity at nominal mass level (m/z> 300-350), only TIMS-FT-ICR MS was able to solve the compositional tendencies of lower aMass spectrometry (MS) is a technique able to ionize simple molecules until complex structures, performing efficiently and dynamically with a wide application using high sensitivity and speed of analysis. Although MS hasconsiderable interest in the scientific society, the application of new technologies in the field of complex matrix analysis still is little explored.Inanalyzes of crude oil, paraffin and condensed aromatic standards, the atmospheric solids analysis probe mass spectrometry (ASAP-MS) is a powerful ionization sourceforcharacterization of samples in original form. Initially, two methodologies were used to determine the chemical composition of the samples: (1) using a temperature gradient ranging from 150 to 600 °C at a heating rate of 150 °C.min-1(parafina) or 50 °C.min-1; (2) with a constant temperaturearound350 °C. ASAP(+)-MS ionized crude oil and paraffin, showing a typical petroleum profile in the range of m/z200 -1400 for both samples. This performancecould relateASAP sourceto detection of compounds of high molecular weight (> 1000 Da). In addition, the AC standardswere identifiedin two ionicforms: radicals, [M]+•and protonated cations, [M+H]+, with minimal fragmentation. Therefore, ASAP was efficient for accessing the chemical composition of polar and non-polar compounds.Analysis of the Cannabis sativaL. plant, were doing by ultra-high performance liquid chromatography coupled to travelingwave ionic mass spectrometry (UPLC-TWIMS MS) using electrospray ionization source in both modes, ESI (±). Hashish, marijuana, and parts of the plant Cannabis sativaL. (flower and leaf) were analyzed. Isomeric compounds were identified inacomplex mixture of cannabinoids, mainly ?9-THC, cannabidiol (CBN-C5and Mw= 310 Da), ?9-tetrahydrocannabinolic acid A and B (?9-THCA-C5A/B and Mw= 358 Da) and their isomers. Analizes by ESI-TWIMSMS were identified three isomers, m/z315/313, 311, and 357, while a high selectivity was observedin UPLC-ESI-TOF MS data, identifying more thanfour isomeric compounds in the single ion acquisition mode (SIM).In other study, we evaluated the use of a high resolution mobility analyzer coupled to ultra high resolution mass spectrometry for molecular characterization of dissolved organic matter. The main goal wastovalidate the reproducibility of trapped ion mobility spectrometry (TIMS), the range of applicability and possible challenges during routine analysis.TIMS coupledto TOF MS and FT-ICR MS showed similar 18performance and high reproducibility. For the analysis of complex mixtures, both platforms were able to aquiriedthe main characteristics. However, the increase ofchemical complexity at nominal mass level (m/z> 300-350), only TIMS-FT-ICR MS was able to solve the compositional tendencies of lower abundance
- ItemEstudo da ionização de hidrocarbonetos do petróleo por APCI(+)FT-ICR MS.(Universidade Federal do Espírito Santo, 2018-08-28) Souza, Lindamara Maria de; Romão, Wanderson; Cunha Neto, Álvaro; Kuster, Ricardo Machado; Fleming, Felipe Pereira; Cardoso, Felipe Mauro RenaAnalyzing paraffins/fractions of saturates, is a difficult task because they are apolar compounds, characterizing a challenge to the mass spectrometry. However, Atmospheric Pressure Chemical Ionization (APCI) source has provided higher applicability. In order to understand and apply APCI(+) MS to analyze paraffins with the best performance and correlate the MS results with other techniques, this work was divided into three sections: i) associate the results of paraffin analysis by analytical techniques to the Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) results. In addition, studying the ionization of paraffins in the presence of polyaromatic. ii) Comparing the ionization efficiency of saturated hydrocarbons (HCs), polyaromatic hydrocarbons (PAHs), and fractions of n-paraffins, as a function of different types of nebulizing gases (synthetic air, nitrogen (N2) and helium (He)) at the APCI source; iii) Study the interaction of petroleum paraffin deposition inhibitors by establishing a correlation between rheology and oil-finger cold tests with gas chromatography results and mass spectrometry of the saturated fraction of the same oils. These studies showed good agreement between APCI(+)FT-ICR MS and High-Temperature Gas Chromatography (HTGC) data through the distribution of carbon numbers plots for paraffin samples. Mwvalues could be compared to Nuclear Magnetic Resonance spectroscopy (RMN) results. Comprehensive Two-dimensional Gas Chromatography (GCxGC) and APCI(+)FT-ICR MS indicated the presence of cyclic paraffin in saturated fractions obtained from the SAP (Saturate, Aromatic and Polar) method. It was noted that PAHs at concentrations greater than or equal to 25 ppm suppressed the ionization of paraffins, but at low concentrations of PAHs (up to 15 ppm) it is possible to ionize paraffins. The evaluation of different ion gas source (nebulizer gas) showed, surprisingly, that the synthetic air presented an excellent signal-to-noise ratio and a lower matrix suppression. For the samples of n-paraffin, synthetic air and He presented similar ionization performance by hydride abstraction ([M-H]+). However, He showed lower mass errors and lower number of molecules with heteroatoms when HCS and PAH standards were analyzed. The correlation between cold-finger and rheology results with MS showed that inhibitors that caused viscosity reduction and deposit mass acted on oils with similar paraffin fractions for the composition of cyclic HCs
- ItemEstudo teórico-experimental por RMN para elucidação estrutural de derivados do Cardanol, Homolicorinas e Cicloheptenonas.(Universidade Federal do Espírito Santo, 2018-08-27) Barbosa, Layla Rosario; Lacerda Júnior, Valdemar; Cunha Neto, Álvaro; Gonçalves, Arlan da Silva; Queiroz Júnior, Luiz Henrique Keng; Morais, Pedro Alves Bezerra
- ItemQualidade química de suco de uva comercial, perfil químico de bananas e açaí juçara e atividade quimiopreventiva de câncer de extratos de bananas(Universidade Federal do Espírito Santo, 2019-06-27) Oliveira, Bruno Gomes de; Endringer, Denise Coutinho; Romão, Wanderson; Costa, Helber Barcellos da; Filgueiras, Paulo Roberto; Cunha Neto, Álvaro; Ventura, José AiresFourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT ICR-MS) allied to electrospray ionization (ESI) is a powerful tool for chemical analysis. In this work, a methodology was developed for the identification and quantification of grape juice with apple juiceadulteration. Anunivariate and two multivariate calibration models (PLS and MRL) were developed. The three models presented results with good precision and accuracy. Eleven samples of commercial whole grape juice were tested. Of these eleven samples, two of them presented apple juice content of approximately 24% m/m and the other nine juices investigated they either did not contain apple juice or had a content below the limit of quantification.In addition, using the ESI(-) FT ICR-MS, it was possible to study the glycidic and phenolic profile of bananas of the Pacovan, Ambrosia, Vitória, Japira, Prata Comum and Tropical varieties at four maturation stages. It was possible to observe the increase of the carbohydrate content in the fruits, during maturation. The Prata (Japira, Vitória, PrataComum and Pacovan) bananas had a monosaccharide content higher than the disaccharide content. Conversely, Gros Michel (Ambrosia) and Maçã(Tropical) had a higher disaccharide content than the monosaccharide content. The polyphenolic profile of these samples indicated a predominance of flavonoids and cinnamic acids, of which 20 polyphenols were detected, for example: epicatechin, hexoside ferulic acid, caffeic acid derivative, gallic acid derivative, proanthocyanidin and quercetin deoxyhexosehexoside.The cancer chemopreventive potential associated with quinone reductase induction,inhibition of the nitric oxideproduction, NF-kB and aromatase were also analyzed.Pacovan cultivar, maturation stage 2, showed high inhibition of NF-kB whereas Japira cultivar, at maturation stages 2, 4 and 7 and Ambrosia, stage 4, showed aromatase inhibition higher than 50%. All samples except Pacovan at maturity stage 7, Tropical at maturation stage 7, showed inhibition of iNOS greater than 80%.The polyphenolic profile of seven genotypes ofjuçara was also investigated in this work. Polyphenols were classified into three phytochemical classes: flavonoids, phenolic acids and anthocyanins, with the most abundant flavonoid class.Among the identified compounds are dihydrokaempferol, protocatecuic hexoside acid, syringe hexoside acid, orientin and malvidin-glycoside.
- Item"Utilização da RMN associada a métodos quimiométricos na caracterização de petróleos e derivados"(Universidade Federal do Espírito Santo, 2016-12-19) Oliveira, Emanuele Catarina da Silva; Cunha Neto, Álvaro; Lacerda Junior, Valdemar; Filgueiras, Paulo Roberto; Menezes, Sonia Maria Cabral de; Chinelatto Júnior, Luiz SilvinoPetroleum products are in general highly complex andconsiderable effort is needed to characterize their chemical and physical properties. Frequently the results of several analyses are urgent and this is compromised by the way the analyses are carried out. Thus, NMR (Nuclear Magnetic Resonance) associated with chemometrics methods have been generating alternative methods to characterize and evaluate physical and chemical properties of petroleum and its derivatives with high precision, reliability and promptitude. Considering its applicability, this work proposes the use of NMR as spectroscopic method and from the integration areas of 1H and 13C NMR’s spectra associated to the chemometric calibration tools (Partial Least Square Method,PLS, and Multiple Linear Regression, MLR) it were determined the following properties in petroleum samples: API gravity, Maximum Pour Point (°C), Cinematic Viscosity (mm2/s at 50°C) and SARA-saturated, aromatic, resins and asphaltenes (%m/m),in order to evaluate the obtained models’ performance. This evaluation was obtained through determination and analyses of the coefficient of determination (R2)of several calculated errors for the calibration and prediction sets. The models were still exposed to statistical tests and their figures of merit calculated. The chemical properties with direct influence on the spectral profile, such as, API gravity, kinematic viscosity and saturated and aromatic contents in SARA models, had generated more robust models and with better predictive capacity, when compared to the models selected for the prediction of the remaining properties, maximum pour point, resins and asphaltenes. A standard recognition tool (partial least squares method with discriminant analysis, PLS-DA) was used to classify petroleum samples into light, medium or heavy oils according to API gravity. In this work, PCA (Principal Component Analysis) models were also constructed aiming the exploratory analysis of a set of spectra of oil derivative samples in order to determine acidity of the original oil considering the structural parameters of the fractions..