Eclética Química

Natural larvicides from the Amazon: a promising alternative in the face of resistance to synthetic insecticides

2026-05-16T06:34:39-03:00

The global rise of arboviral diseases, combined with increasing resistance of mosquito vectors to synthetic insecticides, highlights the urgent need for alternative control strategies. In this context, natural compounds derived from plants have gained attention as sustainable tools for vector management. The Amazon, due to its exceptional biodiversity, represents an important source of bioactive substances with larvicidal potential. Several studies have shown that essential oils extracted from Amazonian plants exhibit high toxicity against mosquito larvae at low lethal concentrations, such as those reported for Siparuna guianensis and Trattinnickia burserifolia. In addition to their potency, these compounds demonstrate environmental selectivity, presenting low toxicity to non-target aquatic organisms and reducing the risk of resistance development due to their complex chemical composition. Although volatility and environmental degradation may limit their persistence, advances in nanobiotechnology, including nano emulsions and inclusion complexes, have improved their stability and applicability. Thus, Amazonian essential oils represent promising candidates for sustainable mosquito control within integrated pest management programs.

Phytochemical analysis and antimicrobial and antifungal potential of extracts and fractions of Poincianella bracteosa

2026-02-08T06:09:12-03:00

The Caatinga is a Brazilian biome with great plant diversity and significant economic and pharmacological potential. It is a valuable source of medicinal resources, with many species used in folk medicine. The study on Poincianella bracteosa highlighted its medicinal properties, such as anti-inflammatory and antimicrobial action. The antimicrobial activities of crude extracts and fractions obtained from different plant parts were evaluated against pathogenic microorganisms. The extracts were obtained through exhaustive percolation with a 70% hydroethanolic solution and fractionated using solvents of lower polarity, resulting in hexane, dichloromethane, and ethyl acetate fractions. The fractions showed greater effectiveness than the crude extracts, with the dichloromethane fraction from the root exhibiting the highest inhibitory activity, with a minimum inhibitory concentration of 0.03 mg/mL against Enterococcus faecalis, Staphylococcus aureus, and Pseudomonas aeruginosa. These results indicate the antibacterial potential of Poincianella bracteosa.

Biochemical analysis of anti-pathogenic bacteria activity of bioactive components from Sclerocarya birrea stem bark via experimental and in-silico approaches

2026-03-03T06:13:32-03:00

In this study, two compounds derived from the bioactive components of Sclerocarya birrea (S. birrea), a plant native to Nigeria, were examined for their biochemical composition, antibacterial effectiveness, and molecular structure. Pyrogallol (94.72 and 46.77%) and hydroxyquinol, which was exclusively identified in the hexane extract, were the main bioactive components extracted from the study plant S. birrea (52.71%). A polyphenolic chemical known as pyrogallol has been shown to have extensive antibacterial activity. The ethanol and hexane bark extracts from S. birrea demonstrated significant antibacterial potential against the entire panel of bacteria tested in this study, indicating that the plant's extracts have a wide range of activity compared to the bacteria of interest most frequently responsible for urinary tract infections. Due to the high phenolic concentration in the plant's bark extract, the antiradical results also showed that S. birrea had a very significant antioxidant capacity. It was found from the molecular docking that pyrogallol could inhibit 80% of the studied receptors.

Synthesis and characterization of SiO2 from Madura Strait sediment with leaching acid treatment

2026-05-11T06:33:30-03:00

Silicon dioxide (SiO₂) was successfully synthesized from Madura Strait sediment. The production process involved a wet digestion step using a strong acid to decompose the sample. Subsequent calcination and purification with strong acid effectively removed impurities, yielding a white sedimentary material. The synthesized SiO₂ was characterized using X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). After impurity removal, the silicon content in the raw sediment increased from 33.5% to 83.3%. XRD analysis confirmed the successful formation of amorphous SiO₂ particles. FTIR spectra indicated the presence of Si–O–Si and Si–OH functional groups, representing silanol and siloxane structures. SEM analysis revealed that the SiO₂ particles formed aggregates with an irregular arrangement, where individual particles appeared loosely associated.

Physical cross-linking of starch hydrogel by short cycles of cooling and heating in the presence of glycerol for potential use as dermal dressing

2026-05-13T06:34:15-03:00

This study focused on developing films from physically cross-linked starch hydrogel with glycerol, utilizing short cooling and heating cycles to enhance cross-linking via the freeze-thaw process. Characterization revealed that 30% glycerol promoted physical cross-linking, further intensified by the thermal cycles, leading to increased film density (AG-R1, AG-R2, and AG-R4). The films demonstrated favorable physicochemical properties for reparative dressings, including easy handling, flexibility, high swelling capacity, water vapor permeability, and low solubility. Notably, the AG-R2 film exhibited the most significant changes, showing increased density and reduced thickness. This indicates a distinct morphology compared to the other films, suggesting an entanglement that restricts solvent molecules (water) incorporation during testing.

Efficient nano-preparation, characterization, and biological evaluation of two Schiff base-derived complexes

2026-04-07T06:24:53-03:00

This study aims to prepare a new Schiff base, 2-[(E)-[2-(2,4-dinitrophenyl)hydrazinylidene]methyl]-1H-pyrrole (NPHP), derived from 2,4-dinitrophenyl hydrazine and 1H-pyrrole-2-carbaldehyde with ratio 1:1. Additionally, two new complexes of this Schiff base were synthesized with transition metal ions, Ni(II) and Cu(II), with ligand to metal ratio 2:1. The complexes were characterized using molar conductivity, FT-IR, UV-Vis, ¹HNMR, ¹³CNMR, XRD, and transmission electron microscopy. Physicochemical properties and spectral results indicate that the conductivity showed an electrolytic nature for these complexes, and the ligand acts as a bidentate chelating agent with octahedral geometry, as supported by FT-IR and UV-Vis analysis. The azomethine (CH=N) nitrogen and pyrrole nitrogen atoms were identified as the coordination sites. Pathogenic bacterial studies for the ligand and its new complexes, Ni(II) and Cu(II), were conducted against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. Based on chelation theory, the metal complexes exhibited higher biological activity than the free ligand, while the complex of Ni(II) was more effective than the complex of Cu(II). Notably, the Schiff base (NPHP) showed no activity against Escherichia coli.

Overview of emerging research of fungi isolated from the Brazilian environment for the biosynthesis of metal nanoparticles

2025-04-03T11:18:13-03:00

Brazil’s rich biological legacy makes it a prime location for studying novel microbes due to its favorable characteristics, which support a wide range of biotechnological applications, including the synthesis of metallic nanoparticles. The number of published studies utilizing fungi from Brazilian habitats for producing metallic nanoparticles has not yet kept pace with this vast microbial richness, making it an underrepresented issue. This review aims to highlight the technological potential of fungus isolated from Brazilian habitats as a biocatalytic source to produce different metallic nanoparticles. A succinct bibliometric diagnosis based on the works in this review is also provided.

Synthesis of chitosan/AC/Fe3O4 nanocomposite and its structural, magnetic, and heavy metal adsorption characteristics

2026-03-04T06:13:34-03:00

The chitosan/activated carbon (AC)/Fe₃O₄ nanocomposite has been successfully synthesized. The nanocomposite was then characterized to investigate its structural, magnetic, and heavy metal Cr(III) adsorption characteristics using XRD, SEM, FTIR, VSM, and ICP-OES. The chitosan/AC/Fe₃O₄ nanocomposite performed a single phase with a cubic inverse spinel structure with a lattice parameter and crystallite size of 8.38 ± 0.01 Å and 5.04 ± 0.09 nm, respectively. The SEM image showed that the morphology of chitosan/AC/Fe₃O₄ tended to be spherical with an average particle size of 51.4 ± 0.4 nm. The FTIR spectrum showed that the chitosan/AC/Fe₃O₄ nanocomposite exhibited the presence of a β-1,4-glycosidic bond at 858 cm^–1 originating from chitosan. The C=C functional group and Fe-O bonds appeared at 1606 and 439–642 cm^–1, indicating the presence of AC and Fe₃O₄. The chitosan/AC/Fe₃O₄ nanocomposite had superparamagnetic properties with a saturation magnetization value of 36.27 ± 0.05 emu/g. Furthermore, the chitosan/AC/Fe₃O₄ nanocomposite had a capacity and efficiency for Cr(III) adsorption of 13.95 mg/g and 27.88% at a contact time of 240 min, respectively.

Effect of fermentation on the organosulfur compound profile and antibacterial activity of black garlic (Allium sativum) extract

2026-03-18T06:20:16-03:00

Black garlic is a derivative product of garlic that offers even more health benefits. During fermentation, various chemical reactions alter the chemical composition of garlic. In this study, the organosulfur compound profile of black garlic was analysed using GC-MS and LC-MS, and its antibacterial activity was also tested. In the initial stage, garlic was fermented at a constant temperature of 60 °C for 24 days. The GC-MS analysis revealed four organosulfur compounds. Meanwhile, the LC-MS analysis detected 16 distinct organosulfur compounds and their quantities at each fermentation stage. One organosulfur compound was consistently detected in LC-MS analysis across all fermentation stages. Antibacterial activity was tested using the paper disc diffusion method against S. aureus and E. coli bacteria. The research findings showed that the most effective black garlic in killing bacteria was fermented for 18 days. This was evident from the largest and most stable diameter of inhibition zones.

X-ray fluorescence and digital imaging: inspiring students with chemistry and creative technology

2026-03-24T06:21:18-03:00

This study explores innovative ways to enhance chemistry education by leveraging smartphone applications and advanced techniques like digital imaging and X-Ray Fluorescence (XRF) spectroscopy. Students analyze coins of varying colors to link visible differences to their chemical compositions. Images are captured, analyzed, and converted into ten-color scale matrices, enabling students to explore color variations beyond the naked eye's perception. XRF spectroscopy, a non-destructive and rapid method, identifies elemental composition, ensuring safe and practical analysis. The activity emphasizes critical skills such as data organization, modern analysis methods, and elemental identification, which are essential in today’s digital age. Designed for senior students, it fosters curiosity about chemistry by demonstrating its everyday relevance. Students learn how Digital Imaging (DI) and chemometric techniques reveal chemical distinctions, with XRF showcasing how specific elements drive color diversity. This hands-on, creative approach highlights the role of technology in education, inspiring deeper engagement and appreciation for chemistry.