Navegando por Assunto "Compostos orgânicos"

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Análise da atividade larvicida de hidrazidas contendo anéis do 1,2,4-oxadiazol e estudo das alterações morfo-histológicas em larvas de Aedes aegypti L. (Diptera, Culicidae)
(2018-08-15) Nascimento, Jéssica da Silva; Oliveira, Lourinalda Luiza Dantas da Silva Selva de; Navarro, Daniela Maria do Amaral Ferraz; http://lattes.cnpq.br/6866049887225410; http://lattes.cnpq.br/7013867423178814
The control of Aedes aegypti is now a major public health challenge because it’s responsible for important arboviruses such as: Dengue, Chikungunya, Zika and Urban Yellow Fever. In this work, we propose a study of the structure-activity relationship of 15 hydrazides against A. aegypti larvae, aiming to identify structural characteristics responsible for the larvicidal activity of the compounds. Fourth instar larvae were submitted to the compounds for 48 hours at different concentrations and then the LC50 was determined. Of the studied compounds, 9 presented considerable potential in the control of A. aegypti (LC50 <100ppm). The compound identied as HCBA presented greater larvicidal activity when compared to the others (LC50 = 20.63ppm) and aroused interest in understanding its mechanism of action. Larvae in the 4th instar were submitted to HCBA (20.63ppm), where they remained for 24 hours. The larvae that reached sublethal state were collected, xed in formoline, included in resin, sectioned, the blades stained by toluidine blue and analyzed by light microscopy. The morphohistological changes of the larvae submitted to the treatment were: high vacuolization in the cytoplasm and disorganization of the epithelium. These results demonstrate that the P-Cloro (HCBA) compound may be effective in controlling A. aegypti for promoting changes at the mesenteric level.
Análise das compreensões de alunos após o desenvolvimento de uma intervenção didática com a temática biogás no ensino de compostos orgânicos
(2019-12-18) Santos, Daysnan Nicolly Arcanjo dos; Firme, Ruth do Nascimento; http://lattes.cnpq.br/7234636790850019; http://lattes.cnpq.br/8660965015640257
Contextualization in science education, and more specifically in chemistry education, has been considered as a way to enable students to find meanings for the content addressed in the classroom. In this perspective, one of the possibilities of contextualization is based on the Freirean Thematic Approach (ATF). Given several possible themes for teaching chemistry from the ATF, we highlight the theme of Biofuels, more specifically Biogas, due to its numerous environmental and economic benefits. Therefore, in this research we aimed to analyze students' understandings after the development of a didactic intervention with the theme Biogas in the teaching of organic compounds. The qualitative research was carried out in a reference school in the high school of the public school system in the north of Recife. Twenty-eight students from the third grade of high school participated, but only thirteen students participated in the study data collection, and was conducted from the following steps: 1) elaboration of the didactic intervention; 2) application of the didactic intervention; and 3) data analysis. Based on the analyzes performed, we can say that the students' understanding: 1) were positive regarding the experimental activity Biogas Production and pointed out relevant aspects that constitute the process of a biodigester, such as the use of organic matter for biogas production. ; 2) related to organic compounds involved in biogas production, such as methane production and combustion with carbon dioxide production; 3) involved relationships between biogas and socioeconomic aspects, such as the cost-benefit of biogas production for sustainability and economic issues, especially for rural areas. However, from the understanding of the identified students, it can be said that the didactic intervention does not seem to have guaranteed students' understanding of other aspects related to organic compounds, such as nomenclature of organic compounds involved in the functioning of the biodigester for biogas. In this direction, aiming at a new research agenda, we propose that the didactic intervention elaborated, developed and analyzed in this research be rethought in order to subsidize the students in the understanding of other chemical contents related to the organic compounds involved in the biogas theme.
Avaliação in vitro de derivados 1,2-alcanodiamina frente ao Mycobacterium tuberculosis sensível e multidroga resistente
(2019-07-09) Laet, João Paulo de Lucena; Pimentel, Lílian Maria Lapa Montenegro; Burgos, Fábia Regina Nascimento Fernando; http://lattes.cnpq.br/3776642205741967; http://lattes.cnpq.br/6066865382706623; http://lattes.cnpq.br/3972432719752724
Mycobacterium tuberculosis (Mtb) is the causative agent of tuberculosis (TB), an infectious-contagious disease, considered one of the deadliest in the world. TB remains a major global public health problem and so far, there has been no effective way to eradicate it. A major change in TB trajectory occurred with the introduction of the first anti-TB drugs and consequently the emergence of resistance forms to antimycobacteria, resistant multidrug tuberculosis (MDR-TB) and extensively resistant tuberculosis (XDR-TB). From this, the need arises for new drugs to be proposed in the treatment of this disease. The present study aims to evaluate diamine derivatives, related to ethambutol, against sensitive Mtb and MDR. Ten compounds derived from the class 1,2-alkanediamine were synthesized and characterized structurally by the pharmaceutical chemistry laboratories of the University of Salamanca and provided through international cooperation. For the biological tests, the standard reference strain H37Rv (ATCC 27294) was classified as a strain sensitive to all drugs used to treat TB and a clinical isolate of a patient affected by pulmonary tuberculosis with a MDR profile, provided by the Health Laboratory Public of Pernambuco. Minimum Inhibitory Concentration (MIC) determined the evaluation of compound activity in 96-well plates by the colorimetric microdilution method. For cytotoxicity (CC50) the MTT test (3- (4,5-dimethylthiazol-2-yl) -2,5-diphenyltetrazolium bromide) was used with the J774A.1 cell line. The selectivity index (IS) was calculated by the ratio of MIC and CC50. The ten compounds tested had a MIC ranging from 4.0 to> 64.0 μM for strain H37Rv and MDR. With respect to CC50, the compounds had a concentration range ranging from 3.9 to 32.8 μM. Compound D15 exerted the best activity against the reference strain (H37Rv) and MDR strain (MDR 1576), however in the cytotoxicity test the compound that presented the best result was D10. Regarding the selectivity index, compounds A4 and A5 were the ones that obtained the best results even though they were below the ideal index. The compounds evaluated in this study showed moderate activity against Mtb and support the continuity of the study of 1,2-alkanediamine derivatives.
Estudo teórico do equilíbrio tautomérico e conformacional de B-dicetonas
(2021-07-21) Silva Filho, Alex Sandro Nascimento da; Batista, Hélcio José; http://lattes.cnpq.br/1234630357325796; http://lattes.cnpq.br/5012359684272037
Beta-diketones are a class of organic compounds characterized through the presence of two carbonyls separated by a carbon unit. Historically, the study of their structures provided the first experimental data on the phenomenon called keto-enol tautomerism, in addition to the particular equilibrium between different enol forms being a source of data for the study of low-energy barrier proton transfer processes. In these works, in general, thermodynamic analyzes are based on nuclear magnetic resonance (NMR) spectroscopy and the evaluation of the constants of keto-enol and enol-enol equilibria are performed from theoretical studies using computational chemistry tools, analyzing minimum structures of each equilibrium. Few theoretical works on beta-diketone systems estimate the energy barriers of tautomerism and its relationship with the substituent and the polarity of the medium, and these few do so using methods of high computational cost with large basis sets, and very often without a study of vibrational and electronic absorption spectroscopies. With the motivation to contribute in this research area, a theoretical study of the conformational, keto-enol and enol-enol equilibria for the following series of B-diketones was carried out in this work: acetylacetone (Acac), benzoylacetone (Bzac), dibenzoylacetone (Dbm), trifluordibenzoylacetone (Btfa), trifluoroacetylacetone (Tfac) and Haxafluoroacetylacetate (Hfac), where low cost computational methods were employed, namely the semi-empirical AM1 method, the density functional theory method with the B3lyp functional and the ab initio Hartree-Fock (HF) method, the last two using the 6-31G basis. The results according to the used methods showed agreement with experimental data from the literature in respect to the ketone tautomers having greater conformational rotational freedom on the ketone ring against to the enolic tautomers. In respect to the keto-enol equilibrium, the influence of the substituent groups on energy barriers is observed, in the case of the studied compounds, the phenyl group (Ph) reducing the barrier height, and the trifluoromethyl group (CF3) increasing it. It is also noted that the transition states (TS) of the keto-enol equilibrium behave according to Hammond's postulate, having their energy destabilized when it has a structure similar to the keto form, which has greater energy than the enol, and stabilized energy, when it resembles the enol tautomer, in general more stable. In the enol-enol equilibrium, the barrier has the same behavior as in the keto-enol case, being influenced by the substituents. Using theoretical vibrational analysis, Gibbs barrier estimation, structural prediction, population analysis of molecular orbitals and prediction of ultraviolet absorption spectra, it was verified that the transition state presents a structure stable enough to provide the establishment of an ultrafast equilibrium between the reagent and product minima. The beta-diketones that have phenyl groups allow to characterize this equilibrium more consistently. To the hydrogen centralization is ascribed a larger ionic or covalent character, a greater TS barrier being found when covalent and smaller when ionic. The Ph substituting group reinforces the ionic character, while the CH3 and CF3 groups the covalent character.
Micofumigação contra fungos associados à doenças pós-colheita no morango
(2021) Cunha, Wallingson Moura da; Gomes, André Angelo Medeiros; http://lattes.cnpq.br/2862163921055255; http://lattes.cnpq.br/9709360130790415
O papel dos compostos auxino-similares extraídos de hidrocarvões de resíduos de milho na germinação de sementes-teste de Lactuca sativa
(2022-12-14) Lima, Edson Thiago Gomes de; Nunes, Ramom Rachide; http://lattes.cnpq.br/6182302726895126; http://lattes.cnpq.br/1474841030315836
Neste trabalho estudou-se a atividade auxino-similar de hidrocarvões líquidos e sólidos obtido a partir de resíduos de milho, preparados por carbonização hidrotérmica (HTC). Os bioensaios foram realizados testando concentrações do hidrocarvão líquido na faixa de 0,0557-5570,0 mg de carbono L-1 ; e hidrocarvão sólido na faixa de 0,026-2600,0 mg de carbono L-1 . A matéria orgânica dissolvida (DOM) foi extraída para realização de testes utilizando hidrocarvão sólido. Os bioensaios foram realizados com sementes de Lactuca sativa. Os métodos instrumentais MEV, ATR-FTIR e Py-GC/MS foram usados para avaliar o efeito da HTC na produção/composição de hidrocarvão. O hidrocarvão líquido apresentou intensa bioatividade, inibindo completamente a germinação das sementes-teste em concentrações acima de 696 mg C L-1 . O hidrocarvão líquido foi consideravelmente mais bioativo que a DOM, mesmo apresentando efeito auxino-similar nos testes de germinação. A análise MEV mostrou como a HTC transformou a superfície da matériaprima, abrindo poros e sulcos nos hidrocarvões. O ATR-FTIR também mostrou que a HTC mudou a composição química dos resíduos de milho, reduzindo os grupos hidroxila e enriquecendo o material com grupos funcionais aromáticos. O Py-GC/MS permitiu a identificação das moléculas envolvidas nos efeitos do tipo AIA: ácidos carboxílicos (lineares e aromáticos) e aminoácidos. A concentração de mais moléculas bioativas, ao invés de sua simples presença na fração do hidrocarvão, determinou o efeito bioestimulante, além de uma boa regressão linear entre a atividade auxino-similar e a concentração de moléculas ativas estimulantes.
Rendimento produtivo do rabanete cultivado sob diferentes lâminas de irrigação e qualidades de adubação
(2019) Sá, Carlos André de Souza; Nascimento, Antônio Henrique Cardoso do; http://lattes.cnpq.br/5216997634308364; http://lattes.cnpq.br/3285445362250128
Water stress along the radish crop cycle may interfere with its development, causing changes in morphology, interfering with the biochemical reactions of the plant. The objective of this work was to evaluate the productive yield of radish (Raphanus sativus L.) cultivated under different irrigation depths and fertilization qualities, from September to December 2019, in the Serra Talhada Academic Unit - UFRPE/UAST. The design adopted was in a factorial scheme (5 x 3) x 4 consisting of five irrigation depths (50, 75, 100, 125 and 150% of The ETc), three sources of fertilization (two organic sources and one mineral source as control treatment) and four replications, in randomized blocks with arrangement of subdivided plots. Campaigns were carried out to obtain biometric and biomass data. Of the biometric parameters, the following parameters were analyzed: shoot height, number of leaves, plant weight, commercial diameter, root system length and root weight. Biomass was performed to determine the efficiency of water use. The irrigation depth of 113.2% of the ETc provided higher production of the commercial part of the radish. It was found that the efficiency of water use is maximized with the use of smaller irrigation depths. It is feasible to partially or fully replace mineral fertilization with organic fertilization for the production of radish.