http://repositorio.ufc.br/handle/riufc/301 Wed, 10 Jun 2026 12:43:12 GMT 2026-06-10T12:43:12Z http://repositorio.ufc.br/handle/riufc/86436 Título: Estratégia de sensoriamento de íons permanganato a partir de um nanocompósito de Pontos Quânticos de Carbono Autor(es): Lima, Ana Stephani Silva de Abstract: Potassium permanganate (KMnO4) is a chemical compound widely used in fish farming and aquaculture activities due to its antibacterial potential. Because it lacks specific regulations, its indiscriminate use can cause harmful effects on the present species. The objective of this study was to develop a sensing platform based on Carbon Quantum Dots for the monitoring and detection of permanganate ions in aquatic matrices aimed at fish farming activities. For the synthesis of these nanoparticles, the solvothermal method was used, with citric acid and ethylenediamine as precursors and ethanol as solvent. Furthermore, the CQDs were also characterized by spectroscopic and structural techniques to identify the functional groups present on their surface, and by microscopic techniques, in which sizes of 1.5 nm were identified. The CQDs exhibited a quantum yield of 19.3% and absorption bands at 240 and 350 nm, moreover, the maximum fluorescence emission behavior at 450 nm was shown to be independent of different excitation wavelengths. Subsequently, experimental condition studies, such as the effect of concentration, pH, and interferents, were carried out to improve and establish the optimal parameters for sensing. Calibration curves with MnO4 ⁻ allowed the determination of the Limit of Detection (LOD) and Limit of Quantification (LOQ) for the sensor, which were 1.0 mg L⁻¹ and 3.05 mg L⁻¹, respectively. In addition, assays with a real sample from a water reservoir located in the city of General Sampaio, Ceará, were performed with additions of KMnO4 standard, obtaining recovery results within the 95–105% error range. Finally, a polymeric support for the sensor was prepared based on CQDs and polyvinyl alcohol, and monitoring tests for the MnO4 ⁻ ion proved efficient based on fluorescence quenching effects, indicating the feasibility of using the sensor in the field in aquatic matrices such as tilapia and other fish species breeding ponds. Tipo: Dissertação Thu, 01 Jan 2026 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/86436 2026-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/86226 Título: Desenho racional e síntese de análogos do fármaco propafenona Autor(es): Aguiar, Francisco Erlando dos Santos Abstract: Propafenone is an antiarrhythmic drug used in the treatment of supraventricular and ventricular arrhythmias. It acts primarily as a sodium channel blocker and, to a lesser extent, as a β-AR antagonist. One issue with sodium channel-targeting antiarrhythmic drugs currently in clinical use is the adverse effects related to cardiac and extracardiac toxicity. Therefore, the development of low-toxicity antiarrhythmic drugs is necessary. One of the main strategies to reduce the toxicity of a given drug is the synthesis of analogs. In this context, the present study proposed the design and synthesis of propafenone analogs. The design of the analogs was guided by SAR analysis and in silico approaches, including the prediction of ADMET properties using the ADMETlab server and molecular docking simulations with the AutoDock Vina program, having as targets the proteins sodium channel Nav1.5, β1-AR, and β2-AR. From SAR analysis, four propafenone analogs were proposed, containing an amino group at position 5 of ring A and saturated nitrogen heterocycles replacing the propylamino group. Pharmacokinetic and toxicological predictions indicated that the analogs have good oral bioavailability and low hepatotoxicity. Molecular docking simulations indicated that analogs rac-6c and rac-6d interact strongly with the targets sodium channel Nav1.5, and β1-AR, with analog rac-6d also interacting strongly with the β2-AR target. Based on these findings, analog rac-6c was selected for synthesis. The commercial substrate 1-(2-hydroxyphenyl)-3-phenylpropan-1-one was initially nitrated at position 5 of ring A. Then, the phenolic group was alkylated with epichlorohydrin, and the epoxide ring was opened in the presence of HCl. Subsequently, the nitro group was selectively reduced using Fe0 nanoparticles. Finally, the key intermediate was aminated with piperidine, yielding the analog rac-6c with an overall yield of 48%. Tipo: Dissertação Mon, 01 Jan 2024 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/86226 2024-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/86115 Título: Estudo químico e biológico de Cordia trichotoma (Vell) Arrab. ex Steud Autor(es): Lopes, Francisca Roziane Severino Abstract: This work describes the phytochemical reinvestigation of Cordia trichotoma (Vell.) Arrab. ex Steud, belonging to the Boraginaceae family. Studies report pharmacological and/or biological activities, such as bactericidal, antifungal, larvicidal against Aedes aegypti and anti-inflammatory, for some species of the genus Cordia. Thus, this study aimed to contribute to the phytochemical knowledge of C. trichotoma, through the isolation and structural characterization of the secondary metabolites of the species. The chemical investigation of the hexane (CTCH) and ethanolic extracts of the heartwood (CTCE) resulted in the isolation of a new sesquiterpene 8,11-epoxy-cadi-3-9-ene (CT6), together with seven sesquiterpenes already described in the literature, -cadinol (CT1); 1,,trihydroxyeudesmane (CT2); 1,,trihydroxyeudesmane (CT3); 1,,,tetrahydroxyeudesmane (CT4); 1,,-trihydroxyoppositane (CT5), 15-oxo--cadinol (CT7), and canangaterpene III (CT8). In addition, they include two phenylpropanoids, 3-(2',4',5'-trimethoxyphenyl)-propanoic acid (CT9) and methyl 3-(2',4',5'-trimethoxyphenyl)-propanoate (CT10). The sesquiterpenes CT4, CT7 and CT8 are being described for the first time in the genus Cordia. The structures of the isolated compounds were characterized through analysis of 1D (1H, 13C and DEPT) and 2D (COSY, HMQC and HMBC) NMR data and comparison with data described in the literature. The acetylcholinesterase inhibitory activity of CTCH, CTCE, hexane fraction of the liquid-liquid partition of ethanolic heartwood extract (CTCEH), dichloromethane fraction of the liquid-liquid partition of ethanolic heartwood extract (CTCED), the ethyl acetate fraction of the liquid-liquid partition of the ethanolic heartwood extract (CTCEA), together with the isolated compounds CT1, CT2, CT3, CT4, CT5 and CT6 were evaluated and among CTCH, CTCE, CTCEH, CTCED and CTCEA showed satisfactory results. The extracts in hexane and ethanol (CTCH and CTCE) were evaluated for cytotoxicity on the human tumor lines HCT 116 (colorectal carcinoma), NCI-H1299 (non-small cell lung cancer) and K562 (chronic myeloid leukemia) and larvicidal activity against Aedes aegypti, in both, only the hexane heartwood extract (CTCH) exhibited low cytotoxic potential in human tumor lines and strong potential as a natural larvicidal agent. Tipo: Dissertação Mon, 01 Jan 2024 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/86115 2024-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/85942 Título: Estudo experimental e teórico das propriedades estruturais e espectroscópicas de ferrocenos quirais e avaliação do potencial ansiolítico Autor(es): Silva, Yana Letícia de Castro e Abstract: Ferrocene compounds are an important class of organometallic complexes that display countless applications in the most varied fields. Among them, chiral ferrocenes stand out as valuable catalysts in asymmetric synthesis. This work describes the experimental and theoretical study of structural and spectroscopic properties of four planar chiral 1,2-disubstituted ferrocenes, including one ferrocenyl-alcohol (1) and three ferrocenyl-amines (2, 3, and 4). Additionally, in vivo biological assays were performed using zebrafish models to evaluate their anxiolytic potential. Vibrational and electronic characteristics were investigated through FT-IR, FT-Raman, and UV-Vis techniques. Electrochemical profiles were obtained through cyclic voltammetry analyses. Determination of absolute configurations was carried out by single crystal X-ray diffraction (XRD) analysis, and chiroptical properties of enantiopure compounds were investigated through electronic circular dichroism (ECD). Theoretical calculations involving Time-Dependent Density Functional Theory (TD-DFT) were performed to further investigate the spectroscopic and electronic characteristics of the compounds. The vibrational modes assignment was made in accordance with theoretical data, which presented similar profiles comparing to the experimental results. UV-Vis absorption spectra also corroborates with theoretical results, with maximum absorption bands around 207, 257 and 435 nm for all compounds. Electronic transitions were assigned and HOMO-LUMO energy gaps were estimated by TD-DFT calculations. Cyclic voltammograms exhibited a quasi-reversible redox process for all compounds and a second redox process for compounds 2 and 4. XRD analyses of the single crystals revealed the obtention of pure enantiomers (Rp)-1, (Rp)-2, (Sp)-3 and (Sp)-4. The results also showed that alcohol (Rp)-1 crystallizes in a tetragonal structure, while amines (Rp)-2, (Sp)-3 and (Sp)-4 crystallize in an orthorhombic structure. The ECD spectra exhibited similar behaviors with intense and opposite absorption profiles between derivatives with inverse configuration. Zebrafish assays revealed that all samples were non-toxic, did not induce anatomical changes in tested animals, and exhibited a likely sedative effect. Compounds 2, 4, and (Sp)-4 showed anxiolytic effect similar to Diazepam (reference benzodiazepine anxiolytic) at all tested doses, while (Rp)-2 exhibited similar effects only with a 4 mg/Kg dose. The tests also suggested that compounds 2, 4, and (Rp)-2 present neuromodulated anxiolytic effects via GABAA. Tipo: Dissertação Mon, 01 Jan 2024 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/85942 2024-01-01T00:00:00Z