http://repositorio.ufc.br/handle/riufc/226 2026-06-12T04:20:04Z http://repositorio.ufc.br/handle/riufc/86711 Título: Estudo racional de triterpenos do tipo lanostano como potenciais inibidores da proteína MYC: avaliação in silico Autor(es): Oliveira, José Augusto Carneiro de Abstract: The MYC protein is one of the most investigated molecular targets for anticancer therapy. The structural characteristics of this intrinsically disordered protein have made inhibitor development a challenge. Lanostane-type triterpenes, such as pisosterol, are secondary metabolites constantly investigated for their anticancer activities. In this study, the anti-MYC potential of 821 lanostane-type triterpenes was investigated using ensemble docking, structural property prediction, pharmacokinetic parameters, molecular dynamics, and free energy calculation using the MM-GBSA method. As a result, the ligands (I-VIII) known as ganoderic acid E (I), ganoderlactone D (II), ganoderic acid Y (III), ganoderic acid Df (IV), lucidenic acid F (V), ganoderic acid XL4 (VI), mariessiic acid A (VII), and phellinol E (VIII) exhibited properties within the filters used. These eight ligands interacted with the molecular target, presenting interaction energies between -8.3 and -8.6 kcal.mol-1. In molecular dynamics, the RMSD, RMSF, radius of gyration, and hydrogen bonding plots revealed that ligands I, IV, VI, and VII interacted satisfactorily with the protein during the simulations, contributing to its conformational and energetic stabilization. The MYC-I and MYC-VII complexes presented free energies of -41.96 kcal.mol-1 and -44.98 kcal.mol-1, respectively. These results demonstrate that lanostane-type triterpenes were able to interact with MYC, forming stable complexes, suggesting that these molecules have the potential to inhibit the target Tipo: Tese 2026-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/86472 Título: Nanopartículas à base de quitosana e polietilenoglicol para encapsulamento do 5-fluorouracil Autor(es): Paiva Junior, José Ribamar Abstract: Cancer is becoming a serious threat to public health. Among non-communicable diseases, it is the most prevalent worldwide. Conventional cancer treatments include chemotherapy, radiotherapy, and, in more severe cases, surgery. Among the chemotherapeutic agents used, 5-fluorouracil is widely used in various types of cancer (colon, stomach, and others). However, it presents some problems, including a very short half-life, low bioavailability, and multiple side effects, including liver and kidney damage. Nanoencapsulation is an alternative to overcome these challenges. Nanoparticles (NPs) have excellent characteristics for controlled drug release applications. They can be prepared using a variety of techniques, with ionotropic gelation being one of the most widely used. This combines oppositely charged polymers, with one of them acting as a cross-linking agent. Chitosan (CH) is a naturally occurring, positively charged polysaccharide extensively used in drug delivery systems. Tripolyphosphate (TPP) can be used as a crosslinking agent to produce nanoparticles. Polyethylene glycol is a synthetic polymer that provides longer intravenous circulation time, better diffusion of NPs in tissue, and prevents interactions with other blood components, increasing the bioavailability of the encapsulated material. In this study, eight nanoparticle systems were developed: four without 5-FU and four with 5-FU. The systems showed encapsulation efficiencies ranging from 9% to 28% and carrying capacities of 8.4% to 12.2%. The FTIR spectra of the systems displayed all the characteristic bands of the starting materials. The diameter of the nanoparticles without 5-FU ranged from 146 nm to 303 nm, and with 5-FU, it ranged from 187 nm to 396 nm. The release presented burst release, releasing approximately 55% within 48 hours of the assay, with release kinetics consistent with the diffusion mechanism model. Scanning electron microscopy revealed that the nanoparticles had a spherical morphology. The PEG-containing systems did not exhibit significant interaction with the protein, suggesting a possible longer circulation time for intravenous administration. Cell viability, however, showed that encapsulated 5-FU was more effective against the HCT-116 cell line, with the systems CH/TPP/PEG14505-FU and CH/TPP/PEG3350/5-FU being the most effective in the evaluations performed. The system CH/TPP/PEG1450/5-FU also demonstrated the emergence of encapsulated 5-FU against the MDA-MB-231 cell line, demonstrating great potential for anticancer applications. Tipo: Tese 2025-01-01T00:00:00Z 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 2026-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/86240 Título: Hidrogéis via base de Schiff a partir de ciclodextrina e polissacarídeos modificados: veículos para curcumina Autor(es): Oliveira, Matheus Xavier de Abstract: Curcumin (CUR) is a polyphenol with anti-inflammatory, antioxidant, and antimicrobial properties; however, its application is limited due to its low solubility and stability under physiological conditions. To overcome these limitations, CUR was initially encapsulated in 2-hydroxypropyl-β-cyclodextrin (HP-β-CD), forming 1:1 inclusion complexes with a high complexation constant (4.65 × 10³ at 25 °C). The use of ultrasound for 10 min (HP-CD/Cur10) increased solubility (from 0.42 to 156 µg mL−1) and stability (half-life from 281 to 2139 min), while also providing antibacterial activity against S. aureus MRSA, greater bioaccessibility, and biocompatibility. In the second stage, HP-CD/Cur10 was incorporated into a hydrogel composed of succinylated chitosan and oxidized cashew gum (GEL-50B), resulting in the GEL-Cur4 formulation, which showed a high curcumin content (440 µg mL−1), mechanical and thermal stability, as well as injectability, self-healing, and adhesiveness. CUR release demonstrated pH responsiveness, increasing intestinal bioaccessibility from 0.20 to 13.5% and enhancing antibacterial activity against K. pneumoniae (85% vs. 59% in the control). In an in vivo wound model, GEL-Cur4 accelerated healing (71% vs. 41% in the control) and positively modulated markers of inflammation and oxidative stress. Therefore, the novel system developed represents a promising multifunctional matrix for wound healing and oral curcumin delivery. Tipo: Tese 2025-01-01T00:00:00Z