Programa de Pós-Graduação em Química - PPGQ/ICEN

URI Permanente desta comunidadehttps://repositorio.ufpa.br/handle/2011/4046

O Programa de Pós-Graduação em Química (PPGQ) do Instituto de Ciências Exatas e Naturais (ICEN) da Universidade Federal do Pará (UFPA). Oferece oportunidade para a formação de Mestres e Doutores nas áreas de Química Orgânica, Físico-Química, Inorgânica e Analítica.

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    Estudo computacional de arilpiperidina e arilpiperazina como inibidores de tirosinase: aplicações cosméticas e terapêuticas
    (Universidade Federal do Pará, 2025-04-08) BENTES, Beatriz Alves; SILVA, José Rogério de Araújo; SILVA, Jerônimo Lameira; http://lattes.cnpq.br/7711489635465954
    Tyrosinases (TYR) catalyze the oxidation of phenols and catechols, playing a crucial role in melanogenesis, which regulates melanin production and provides protection against UV radiation. However, pigmentation-related disorders drive the search for effective TYR inhibitors. Compounds such as hydroquinone, arbutin, and kojic acid have limitations, highlighting the need for new inhibitors. In this study, arylpiperidine- and arylpiperazine-based compounds demonstrated potent inhibitory activity against TYR. Computational analysis included molecular docking, molecular dynamics (MD) simulations, and binding free energy calculations using the Linear Interaction Energy (LIE) method, revealing a strong correlation with experimental affinity data. To enhance the understanding of structure-activity relationships (SAR), Free Energy Perturbation (FEP) transformations were performed for selected ligand pairs. Additionally, Density Functional Theory (DFT) calculations were applied to inhibitors L04 and L19, enabling the determination of electronic descriptors and frontier molecular orbitals. The inhibitors interact with TYR mainly through electrostatic interactions with the copper ion and van der Waals forces with critical residues such as Phe197, Pro201, Val218, Asn205, and Arg209. These findings are promising for both cosmetic and therapeutic applications, enabling the development of skin-lightening agents to treat melasma and sunspots, as well as potential treatments for hyperpigmentation-related diseases and melanomas. The development of more selective inhibitors with lower toxicity may expand the clinical and cosmetic use of these compounds, offering safer and more effective alternatives for melanin production modulation.
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    Influência do ph do banho e da densidade de corrente no comportamento capacitivo de eletrodos de mno2 obtidos por eletrodeposição anódica
    (Universidade Federal do Pará, 2025-01-30) RENTE, Arthur de Farias Silva; NOCE, Rodrigo Della; http://lattes.cnpq.br/3734170057844016
    MnO₂ electrodes are obtained by anodic electrodeposition on stainless steel substrate at room temperature from a 0.1 M manganese sulfate bath, under different current densities, ranging from 200 µA·cm⁻² to 5 mA·cm⁻² (galvanostatic mode), and pH values from 2 to 6. The material morphology is analyzed by scanning electron microscopy, revealing compact, homogeneous, and two-dimensional film deposition, with the presence of microcracks that provide active sites for the incorporation of sodium sulfate (Na₂SO₄) electrolyte ions, enhancing the material's specific capacitance. At low current densities, such as 200 and 500 µA·cm⁻², the formed film is homogeneous, while increasing the current density to 2 mA·cm⁻² results in cracks on the material's surface. Morphological changes are also identified as a function of pH: near neutrality (pH 6), cracks become evident, whereas in more acidic pH levels, such as 2 and 3, the structure remains uniform. At pH 4, an irregular structure is observed. The structure of the formed films, analyzed by by X-ray diffraction, reveals the presence of the alpha (α) phase under all studied conditions, regardless of the applied current density and bath pH. Electrochemical characterization of the films, carried out using cyclic voltammetry and charge-discharge curves (chronopotentiometry), indicates a working potential window of 1.1 V and specific capacitance values ranging from 13 to 371.8 F·g⁻¹, depending on the applied current density and bath pH. The highest specific capacitance value is obtained at a current density of 2 mA·cm⁻² and pH 4.
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