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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    Obtenção de filmes finos de ligas de alta entropia à base de CoFeNi por eletrodeposição em meio aquoso
    (Universidade Federal do Pará, 2025-04-25) FREITAS, Gregório Felipe do Nascimento; NOCE, Rodrigo Della; http://lattes.cnpq.br/3734170057844016
    High-entropy alloys, also called multicomponent alloys, are alloys that have five or more elements whose composition is formed between 5% and 35% in terms of atomic composition of the elements. These alloys have gained prominence recently because they present very distinct and attractive properties in relation to conventional alloys composed of a single major element. In this context, the alloys have been produced by different physical and chemical methods. The present work addresses the subject of obtaining thin films of high-entropy alloys based on CoFeNi by the electrodeposition technique in aqueous medium, with additions of elements such as Mo, Mn, Sn and W. A simple and low-cost technique in relation to other methods proposed in the literature. By using the direct current (galvanostatic) method at room temperature and by varying the current density to obtain thin films in a range of 5 to 100 mA/cm2, the high entropy alloy CoFeNiMoW and the possibility of obtaining the CoFeNiMnSn alloy on a brass substrate (CuZn) are demonstrated. The electrodeposited films are characterized by Energy Dispersive Spectroscopy (EDS), Scanning Electron Microscopy (SEM), X-ray Diffractometry (XRD) and Mossbauer Spectroscopy techniques. EDS analyses reveal that the composition of the alloys is strongly influenced by the applied current density. In the high entropy alloy with five elements CoFeNiMoW formed from applied current density of 50 mA cm-2, the atomic proportion obtained is Co 30%, Fe 21%, Ni 19%, Mo 25%, W 5%. For the CoFeNiMnSn alloy, its composition formed by means of a current density equal to 50 mA cm-2 is Co 26.2%, Fe 33.8%, Ni 5.5%, Mn 1.8%, Sn 32.6%, thus evidencing the formation of alloys with five elements by the proposed method.
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