https://repositorio.ufu.br/handle/123456789/18812 Thu, 01 Oct 2026 22:06:07 GMT 2026-10-01T22:06:07Z https://repositorio.ufu.br/handle/123456789/50327 Title: Isolamento e identificação de alcaloides piperidínicos minoritários presentes nas flores de Senna spectabilis (Fabaceae) Abstract: Senna spectabilis belongs to the Fabaceae family and is popularly known as cassia. This species is widely used in urban landscaping and is considered an important source of specialized metabolites, particularly the major piperidine alkaloids (–)-cassine and (–)-spectaline. These compounds have attracted scientific interest due to their acetylcholinesterase inhibitory activity, an enzyme associated with Alzheimer’s disease. Previous studies have reported the occurrence of epimers of (–)-cassine and (–)-spectaline at C-6 of the piperidine ring, known as 6-iso-cassine and 6-iso-spectaline. The investigation of these diastereomers is relevant because changes in stereochemistry may result in different physicochemical properties and potentially affect their biological activities. Therefore, this study aimed to expand the knowledge of the piperidine alkaloids present in S. spectabilis, focusing on the isolation and identification of minor metabolites. Chromatographic techniques, including thin-layer chromatography (TLC), column chromatography (CC), high-performance liquid chromatography (HPLC), and gas chromatography with flame ionization detection (GC-FID), were employed for the separation of the compounds. The isolated metabolites were identified by mass spectrometry (MS) and 1H nuclear magnetic resonance spectroscopy (1H NMR). The results demonstrated that S. spectabilis is an important source of specialized metabolites, whose separation required the application of advanced analytical techniques, particularly HPLC-MS and GC-FID. The isolated diastereomers and homologues provide a basis for future studies aimed at determining the absolute stereochemistry of their stereogenic centers, as well as evaluating their biological activities and elucidating their mechanisms of action. Mon, 03 Aug 2026 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/50327 2026-08-03T00:00:00Z https://repositorio.ufu.br/handle/123456789/50087 Title: Redução eletrocatalítica de CO2 utilizando um novo complexo de Re(I) contendo o ligante (z)-n-metil-2-(6-oxo-1,10-fenantrolin-5 (6H)-ilideno) hidrazinacarbotiamida Abstract: Tricarbonyl rhenium(I) complexes, commonly represented as fac-[Re(CO)₃(NN)Cl], where NN denotes bipyridine-derived ligands, have been extensively investigated as homogeneous catalysts for CO₂ reduction. This study aimed to synthesize a new complex, fac-[Re(CO)₃(Phmt)Cl], where Phmt = (Z)-N-methyl-2-(6-oxo-1,10-phenanthrolin-5(6H)-ylidene)hydrazinecarbothioamide, and to investigate its electrochemical behavior as a potential electrocatalyst for CO₂ reduction. The synthesis of fac-[Re(CO)₃(Phmt)Cl] was carried out by first preparing the Phmt ligand under reflux in toluene, followed by reaction with the metal precursor [Re(CO)₅Cl] under reflux to afford the desired complex. The product was characterized by Fourier-transform infrared (FTIR) spectroscopy and ¹H nuclear magnetic resonance (¹H NMR) spectroscopy to confirm its molecular structure. The ¹H NMR spectrum displayed signals predominantly between 7 and 15 ppm, with the two most downfield resonances assigned to the amine hydrogen atoms, while the remaining signals corresponded to the aromatic protons. The FTIR spectrum provided further structural confirmation, exhibiting characteristic bands assigned to ν(N–H) (≈3268 cm⁻¹), ν(C≡O) (≈2027, 1900, and 1890 cm⁻¹), and ν(Re–N) (≈260 cm⁻¹), indicating the presence of amine groups, the facial geometry of the tricarbonyl complex, and metal–ligand coordination, respectively. The electrochemical properties were investigated by cyclic voltammetry (CV) in anhydrous dimethylformamide (DMF) under argon and CO₂ atmospheres. Under argon, the complex exhibited an irreversible oxidation peak corresponding to the Re(I)/Re(II) redox process. In the cathodic region, three irreversible reduction peaks were observed at −1.0, −1.6, and −2.1 V vs. Fc⁺/Fc, consistent with values reported for structurally related compounds. Under a CO₂ atmosphere, a significant catalytic current enhancement was observed (Ic/Ip = 2.41), with the first reduction peak shifting to −1.93 V vs. Fc⁺/Fc. These electrochemical results indicate that the synthesized complex is a promising candidate for the electrocatalytic reduction of CO₂ to CO. Wed, 29 Jul 2026 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/50087 2026-07-29T00:00:00Z https://repositorio.ufu.br/handle/123456789/49735 Title: Cremes hidratantes faciais anti-idade: uma revisão dos mecanismos de ação dos diferentes ativos disponíveis no mercado Abstract: Skin aging is a complex and inevitable biological process driven by intrinsic factors, such as genetics and metabolism, and extrinsic factors, with exposure to ultraviolet radiation (UV), pollution, and lifestyle standing out as the primary accelerators of extracellular matrix degradation. This study conducted a literature review on the process of cutaneous senescence and analyzed the efficacy of active ingredient classes, mechanisms of action, and formulations used to prevent and treat its signs. Skin physiology reveals that the depletion of structural components, such as collagen, elastin, and glycosaminoglycans, combined with the collapse of the calcium ion gradient, underlies the development of wrinkles and skin laxity. Analysis of the active ingredients demonstrated that the efficacy of these cosmeceuticals depends on crucial variables, such as active ingredient concentration, vehicle formulation, and chemical stability in the presence of oxidizing species. Anti-aging actives, including humectants, retinoids, alpha-hydroxy acids, peptides, and antioxidants, function through hydration, cell signaling, epidermal renewal, and free radical neutralization. However, many formulations require the combination of photoprotection and encapsulation technologies to maximize delivery and skin tolerability. Given the growing market driven by contemporary aesthetic pressures, the pursuit of anti-aging treatments should be grounded in a scientific understanding of their chemical mechanisms and conscious consumer choices, avoiding the unnecessary or inappropriate use of potent products while promoting skin health and consumer safety. Thu, 30 Jul 2026 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/49735 2026-07-30T00:00:00Z https://repositorio.ufu.br/handle/123456789/49430 Title: Suplementação esportiva sem cafeína: análise da composição química e da influência do efeito placebo sobre o desempenho físico Abstract: The consumption of pre-workout ergogenic aids has become established as a strategy for the acute optimization of physical performance. Traditionally, the effectiveness of these products is attributed to the presence of central nervous system stimulants. However, the indiscriminate use of these substances has been associated with significant toxicological risks, including epi- sodes of tachycardia and arrhythmias, especially among young individuals. Given this safety scenario, theexpansionofthemarketforstimulant-free(stim-free)formulationsraisesquestions regarding their actual effectiveness. The present study aimed to analyze the composition of these alternative formulations and investigate the influence of the psychobiological response on performance. The methodology consistedofanexploratoryliteraturereview. Itwasobservedthat, althoughtheinitialintention was to describe the chemical mechanisms of the placebo phenomenon, the current scientific literature prioritizes the analysis of clinical outcomes and experimental evidence. The results showed that the absence of stimulants is compensated by the action of cons- tituents such as creatine, beta-alanine, and L-citrulline, which are fundamental for energy resynthesis, vasodilation, and buffering of muscle acidosis. At the same time, experimental evi- denceindicatesthattheexpectationofefficacyiscapableofactivatingneurobiologicalpathways related to reward and pain modulation, thereby mimicking performance-enhancing effects. It is concluded that the efficacy of these formulations does not lie exclusively in pharmaco- logy, but in the combination of competent physiological substrates and applied sensory engine- ering strategies, validating the use of approaches that integrate metabolic and psychobiological processes. Tue, 17 Mar 2026 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/49430 2026-03-17T00:00:00Z