Abstract in English:

Violacein is one of the very attractive biomolecules and a purple pigment known worldwide because of its pharmacological potential as an antibacterial, antifungal, antiviral, anticancer, antiulcerogenic, trypanocide, and immunomodulatory drug. It is mainly produced through biosynthesis using bacterial strains, recombinant strategies, and synthetic biology. There are also a few total organic synthesis proposals. Nevertheless, low yields, difficulties with bacterial cell growth inhibition, and laborious biosynthetic and total synthesis pathways have impaired the upscaling of violacein fabrication. Another major challenge is the purification strategy that still has not been solved despite efforts and improvements, a reason for the very high costs, impairing the violacein-wide applications even as a drug. The current review aims to address different aspects of violacein, such as its production, purification, biological activities, and toxicity, helping to enhance its viability for biotechnological applications.

Abstract in English:

The cosmetics industry is expanding, with growing demand for natural and green products, including “cosmetic thermal water”. Brazil, the fourth largest cosmetic market of the world, has seen increased availability of these products, which may contain ingredients such as natural extracts, moisturizers, and preservatives, which can be potential sources of contamination with carcinogenic N-nitrosamines. This study aimed to map cosmetic thermal waters in Brazil, assess their composition and risk of N-nitrosamines formation, and develop and validate an analytical method for detecting N-nitrosamines in these products. A bidimensional liquid chromatography coupled with tandem mass spectrometry method was developed and validated for the precise quantification of N-nitrosodiethanolamine, N-nitrosodimethylamine, N-nitrosomorpholine, and N-nitrosodiethylamine in cosmetic thermal waters. The method was effective for most of the commercial samples analyzed. For accurate detection in the case of samples with more complex matrices, an offline solid phase extraction preparation method was also developed, ensuring reliable quantification for a variety of formulations. No detectable levels of the four N-nitrosamines were found in the 12 samples evaluated. The findings demonstrated the effectiveness of the method for monitoring contamination with N-nitrosamines in cosmetic thermal waters and indicated the need for ongoing surveillance and detailed analysis of formulations to ensure product safety.

Abstract in English:

This study presents the first quantification of polycyclic aromatic hydrocarbons (PAHs) deposited on the personal protective equipment (PPE) of Brazilian firefighters during a controlled training exercise. Twelve participants took part in the simulation, and samples were collected before and after exposure using wipes from gloves, chest, sleeves, and shoulders. Eight PAHs were detected and quantified by gas chromatography-mass spectrometry analysis (GC-MS), including naphthalene and phenanthrene, which showed the highest prevalence. Contamination increased significantly after training, even for exposures shorter as 3 min, with concentrations ranging from 0.007 to 1.066 µg mL-1. A positive correlation between exposure time and PAH concentration was observed, with the highest levels found in the instructor exposed for 25 min. These findings corroborate international reports indicating that firefighting activities result in occupational exposure to PAHs and highlight the potential for contamination even under controlled conditions. Additionally, they underscore the relevance of monitoring and decontaminating PPE to prevent long-term exposure and cross-contamination.

Abstract in English:

Tableware is a domestic object that reflects everyday socio-cultural activities, making it a valuable subject for archaeometric studies. This study aims to chemically analyze crockery fragments from the 18th- and 19th-century colonial period using portable energy-dispersive X-ray fluorescence spectrometry (pEDXRF) and chemometric treatment for technological reconstruction and chemical similarity assessment. Analysis of the paste and glaze revealed that SiO2, Al2O3, and CdO are the main constituents. Due to a CaO content of less than 6%, the paste was classified as non-calcareous clay. The presence of PbO2 and CoO in the glaze composition identified the dishes as fine pearlware, artifacts produced from the 18th century onward. Principal Component Analysis (PCA) defined affinity clusters only for the glazes, while a more specific analysis using a ternary diagram revealed two distinct groups for both pastes and glazes, differentiated by the presence or absence of cadmium. This finding highlights an atypical and unique characteristic of the analyzed samples, particularly given the significant Cd content identified.

Abstract in English:

A supercapacitor is an energy storage device that has a much higher capacitance than conventional capacitors. It operates through electrical double layer mechanisms and electrochemical pseudocapacitance, allowing it to store and release energy quickly. For this task, graphene is an ideal candidate to perform this purpose. In this article, through multifactorial experimental planning, graphite was exfoliated in a ball mill over a period of 2, 4, 8, 12 h of milling. The samples were structurally analyzed by X-ray diffraction, showing the evolution of the crystalline phases present in the material, demonstrating that crystallinity increased 62 times with milling time. Raman spectroscopy analyses confirm the exfoliation of graphite and formation of graphene under the best conditions obtained in multifactorial planning. The electrochemical analysis showed the relation between the structural modification of the material through the milling process and its electrochemical behavior, indicating that the graphene obtained from the graphite milling reaches a specific capacitance of 274.75 F g-1, capacitance 53 times greater than that presented by the manually ground material (5.2 F g-1). This result indicates that high-energy ball milling can be an efficient synthetic route for the application of multilayer graphene as a supercapacitor.

Abstract in English:

In the present work, synthesis, characterization, and biological assays of seven N-acylhydrazones derivatives of isoniazid and their corresponding silver(I) complexes are described. The compounds were characterized by elemental analysis, infrared (IR) and 1H, 13C and 1H-15N nuclear magnetic resonance (NMR) spectroscopic measurements, and molar conductivity over 48 h assays. Density functional theory (DFT) studies also were employed in order to structural elucidation of the seven silver(I) complexes. All the synthesized silver complexes have shown minimum inhibitory concentration (MIC90) values against Mycobacterium tuberculosis - MtbH37Rv (ATCC 27294) lower than 7.421 mg L-1. The AgIZBEN complex showed the most promising anti-tuberculosis action, with MIC90 of 0.956 mg L-1 and selectivity index (SI) = 29.3 while the AgIZpAN showed SI higher than 460 and MIC90 of 1.077 mg L-1. The free acylhydrazones derivatives also showed SI higher than 20.

Abstract in English:

Our chemical studies on Renealmia petasites led to the isolation of (+)-hirsutanonol, a diarylheptanoid that presents several inconsistencies in the literature regarding its absolute configuration (AC). In this paper, a detailed investigation of optical rotation (OR) and electronic circular dichroism (ECD) chiroptical properties supported by quantum chemical calculations was carried out to unequivocally determine its AC. In addition, our analysis indicated the source of conflicting AC results for hirsutanonol and its derivatives came from the direct comparison of experimental OR and ECD data obtained for structurally related molecules with different chromophoric systems. As an alternative, ECD spectroscopy combined with density functional theory (DFT) calculations is proposed as a more reliable and sensitive technique for the stereochemical investigation of diarylheptanoids.

Abstract in English:

Sewage sludge serves as a promising raw material for producing activated biochar (BC), offering both environmental and economic benefits. This work aimed to optimize the synthesis of biochar (BC) from cosmetic industry sludge using response surface methodology (RSM) with central composite rotational design (CCRD) and to assess its effectiveness in removing the antibiotic enrofloxacin (ENR) from synthetic effluents. The input variables considered were (i) residence time in the reactor and (ii) impregnation ratio (NaOH/biomass). The response for optimization was the iodine number. The sludge underwent pyrolysis at 550 °C under a nitrogen atmosphere. The optimized biochar (OBC) had a macroporous structure with a specific surface area of 46.1 m2 g-1 and a calorific value of 4146 kcal kg-1. The bio-oil contained nitrogenous compounds and alcohols. The effectiveness of the OBC in adsorbing ENR in aqueous systems was assessed. Kinetic assays showed an equilibrium time of 90 min, with the pseudo second order model best fitting the experimental data. The Langmuir isotherm model best described the adsorption (qmax = 15.83 mg g-1). The material is competitive with commercial adsorbents. This work underscores the potential of industrial sludges as a sustainable source for BC, contributing to pollution reduction and promoting circular economy practices.

Abstract in English:

The mixed-valence polyoxovanadate (MV-POV) (NBu4)5[I@VIV10VV8O42] (V18), where NBu4+ = tetra-n-butylammonium, was synthesized, forming dark green films with good adherence to glass and poly(vinyl chloride), PVC, directly from the supernatant of the reaction. V18 solid was characterized by elemental analysis, spectroscopic techniques, thermal analysis and scanning electron microscopy (SEM). V18 showed an irreversible phase transition from microcrystalline to amorphous at 66 °C. Flexible, translucid, green films, named PVC+V18, were prepared from a solution of PVC and V18 (1 wt.%, cyclohexanone) through solvent-casting and spin coating methods. Spectroscopic analysis indicated that V18 retained its polynuclear structure within PVC. The glass transition temperature (Tg) of PVC decreased from 82.6 to 30.3 °C after V18 incorporation, revealing a plasticizing effect. Energy dispersive spectroscopy (EDS) mapping and atomic force microscopy (AFM) analysis showed homogeneous films with low roughness (mean roughness (Ra) = 0.288 nm). The direct and indirect optical energy gaps of PVC reduce from 5.20 to 4.73 eV and from 4.38 to 3.45 eV, respectively. Molecular docking simulations revealed a strong interaction, of 112.6 kcal mol-1, between the polymeric chain and V18, primarily mediated by C-H···O hydrogen bonds. Thermal studies of PVC+V18 films showed an irreversible color change from green to black (30 h at 100 °C; 20 min at 170 °C).

Abstract in English:

Ab initio predictions of hydrogen adsorption isotherms in covalent organic frameworks-10 (COF-10) were performed based on the calculation of Gibbs free energy changes. First, structures of adsorption products corresponding to seven possible adsorption sites were optimized. Hydrogen tends to be adsorbed along the pore surface rather than between the two neighboring layers of COF-10. Second, thermodynamic data of adsorption processes were calculated. The calculated adsorption enthalpy reproduces the experimental result well (around -4 kJ mol-1). Two schemes have been adopted to calculate adsorption entropies and the corresponding Gibbs free energies of adsorption, and exhibiting big differences between the results of the two schemes. At last, adsorption isotherms have been plotted based on adsorption equilibrium constants. The scheme adopting frustrated translation with an average relative error of 10.50% is much better than the traditional scheme treating all the six degrees of freedom of hydrogen as vibrational modes with an average relative error of -90.24%.

Abstract in English:

In this work, Raman spectroscopy was employed to identify compounds present in different ripening stages of various exocarp varieties of peppers from the Solanaceae family, pink peppercorns (Anacardiceae), and black and white peppercorns (Piperaceae). In situ analysis of Solanaceae peppers revealed the characteristic bands of phenolic compounds, carotenoids, fatty acids, and alkaloids such as capsaicin. In the malagueta peppers, habanero, “biquinho”, and red karneval, a shift of the ν(C=C) stretching bands of carotenoids to lower wavenumbers and an increase in the band intensity were observed during ripening. In pink peppercorns, analyses of the peel and seeds at different ripening stages did not show significant changes. However, bands attributed to anthocyanins, such as pelargonidin, were observed, suggesting that these flavonoids are responsible for the color of the peel. Analyses of black and white peppercorns revealed characteristic bands mainly attributed to piperine. The assignment of Raman bands was proposed through comparison with literature data and spectra obtained by the Density Functional Theory (DFT) method. The sum of the theoretical spectra was used to simulate the spectral profile and the contribution of each substance in the experimental spectra.

Abstract in English:

Cross-linked polymer microgels were synthesized via precipitation polymerization, and the influence of intermolecular interactions between methacrylic acid (monomer) and donepezil (anticholinergic drug) on microgel properties were investigated. Ion pair formation, confirmed by proton nuclear magnetic resonance spectroscopy (1H NMR) and nuclear Overhauser effect (NOE) studies, enabled molecular imprinting using donepezil as a template. The microgels were characterized for their adsorption capacity, swelling behavior, mucin binding, and drug release kinetics. Imaging by atomic force microscopy (AFM) and field emission gun scanning electron microscopy (FEG-SEM) revealed dry particles ca. 120-200 nm in size, which swelled to ca. 1 µm in aqueous media. Swelling increased with pH and ionic strength, and the microgels exhibited high adsorption capacity (ca. 200 mg g-1). Donepezil adsorption followed the Sips model, indicating heterogeneous binding sites. Molecular imprinting in oil-based formulations modulated drug release via Higuchi kinetics, attributed to enhanced interactions within the hydrophobic vehicle. These findings demonstrate the potential of drug-polymer interactions in designing tunable drug delivery systems for clinically relevant doses. Donepezil base and drug-free microgels exhibited lower cytotoxicity than microgels with adsorbed donepezil in human lung fibroblast (MRC-5) cells, possibly due to the swelling and agglomeration of these polymer particles. Additional studies, including histological analysis of mucosal tissues at potential application sites, should be conducted in animal models to confirm whether microgels exhibit increased cytotoxicity.

Abstract in English:

This paper presents the anxiolytic potential of the major constituents of cashew nut shell liquid (CNSL), anacardic acid (AA), cardanol (CDN), and cardol (CD), and CNSL-derived silver nanoparticles (AgAA and AgCD) compared to diazepam (DZP) in zebrafish (Danio rerio) and in silico by docking on the GABAergic system. CD and CDN were extracted and purified using silica gel column chromatography, and AA was extracted by acid-base reaction. Silver nanoparticles were synthesized through microwave-assisted reduction of silver nitrate with CNSL constituents. UV-Vis spectroscopy presented surface plasmon resonance extinction peaks at 423 (AgAA) and 414 nm (AgCD). Transmission electron microscopy revealed spherical nanoparticles within liposomes of AA and CD. All tested drugs had no toxicity below 40 ppm. CDN (40 ppm) decreased locomotion by 76.98%, approaching DZP (90.67%). AA, CDN, CD, and AgAA surpassed the anxiolytic effect of DZP in the light/dark test, while AgCD was ineffective. Flumazenil reversed the anxiolytic effect of all compounds, confirming GABAergic mediation. Molecular docking revealed that di-unsaturated CD had the highest GABAA affinity, and di-unsaturated AA mimics the hydrophobic profile of DZP. Results confirmed the anxiolytic potential of CNSL, and the synthesis of CNSL-capped AgNPs gives water-soluble anxiolytic drugs with a controlled-release mechanism.

Abstract in English:

Melipona seminigra geopropolis is a significant income source for many people in Amazonia due to its medicinal and nutritional properties. This study describes the chemical composition of geopropolis from local producers across five different locations in Manaus and Iranduba in the State of Amazonas, Brazil. Using chemical analysis techniques such as nuclear magnetic resonance, mass spectrometry (ion-trap analyzer), and liquid chromatography coupled to high resolution mass spectrometry (time-of-flight analyzer), the presence of organic acids, flavonoids, and benzophenones was annotated. Chemometric analysis, including principal component analysis (PCA) and hierarchical cluster analysis (HCA) of the mass spectrometry data, revealed a relationship between the chemical composition of the samples and the geographical sources. The antioxidant activity measured using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical assay showed values ranging from 57.01 to 142.10 µg mL-1, while total phenolic content ranged from 248.85 to 367.01 µg mL-1. These findings provided new insights into a product that has not been extensively studied.

Abstract in English:

Phytochelatins (PCs) are thiol-rich peptides essential for detoxifying toxic metals such as arsenic (As) and selenium (Se) which compete for sulfhydryl groups involved in detoxification within plant cells. This study employed paper-spray mass spectrometry (PS-MS) to detect glutathione (GSH), free phytochelatins (PC2 and PC3), and their metal complexes (As-PC3 and Se-PC2) in golden flaxseed roots. Plants were exposed to arsenate (0 and 50 μmol L-1) and selenite (5 and 25 μmol L-1). Root tissues were cryogenically ground and extracted with formic acid. Inductively coupled plasma mass spectrometry (ICP-MS) quantified total As and Se, while PS-MS allowed direct detection of thiol-containing compounds and their complexes. Fragmentation patterns confirmed the presence of GSH, reduced PC2, reduced PC3, Se-PC2, and As-PC3. Selenium exposure enhanced GSH biosynthesis, whereas arsenic induced phytochelatins production, suggesting a response to metalloid stress. The results highlight the key role of free PCs and their metal-bound forms in detoxification and demonstrate the utility of PS-MS and tandem MS in profiling metal-thiol complexes in plant tissues. The findings provide new insights into metal detoxification pathways and contribute to a deeper understanding of plant tolerance mechanisms in contaminated environments.