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Síntese e avaliação da atividade antileishmania de derivados piridínico-imidazolínicos

2026-02-24T06:20:42Z

Title: Síntese e avaliação da atividade antileishmania de derivados piridínico-imidazolínicos Abstract: Neglected Tropical Diseases (NTDs) remain a major global public health challenge, particularly leishmaniasis, whose high incidence and toxicity of current therapies demand new therapeutic alternatives. In this study, nine hybrid compounds were designed, synthesized, and evaluated through aromatic nucleophilic substitution (SNAr) reactions between pyridinic nuclei and sulfur-containing heterocycles (benzimidazole, benzoxazole, and benzothiazole). Molecular hybridization and bioisosterism strategies were applied to obtain derivatives with enhanced antiparasitic potential and improved pharmacokinetic profiles. The compounds were characterized by NMR spectroscopy (1H and 13C) and assessed for leishmanicidal activity against intracellular amastigotes of Leishmania infantum and cytotoxicity on human macrophages (THP-1). Compound 5 exhibited the best biological performance (IC₅₀ = 1.17 μM; Selectivity Index > 50), indicating high potency and low toxicity. In silico SwissADME analysis confirmed favorable lipophilicity and oral bioavailability. Overall, the molecular hybridization between pyridinic and sulfur heterocyclic cores proved to be a promising strategy for the development of new antileishmanial agents.

Caracterização e avaliação do processo de adsorção como alternativa de tratamento para efluente gerado durante a gaseificação de resíduos sólidos

2026-01-14T06:19:15Z

Title: Caracterização e avaliação do processo de adsorção como alternativa de tratamento para efluente gerado durante a gaseificação de resíduos sólidos Abstract: The gasification of solid waste, although an efficient alternative for energy generation, produces liquid effluents with a high pollutant load, which require proper treatment to enable their disposal or reuse. In this context, the present study aimed to evaluate the adsorption process as a treatment alternative, with emphasis on the reuse of the effluent in the industrial process itself. For this purpose, two adsorbents were tested: commercial activated carbon and biochar produced from açaí seed. Initially, the effluent was characterized in terms of physicochemical parameters, showing high acidity (pH 3.7), outside the range permitted by CONAMA Resolution No. 430/2011, which establishes a pH between 5.0 and 9.0 for discharge into water bodies. In addition, the effluent presented a high organic load, measured as chemical oxygen demand – COD (6875 ± 321 mg O₂/L), high dissolved organic carbon – DOC (1620 ± 9 mg/L), significant presence of oils and greases (392 ± 83 mg/L), and intense true color (1399 ± 49 mg/L Pt/Co), all considerably high according to the same resolution, reinforcing the need for pretreatment prior to disposal or reuse. To verify the efficiency of the adsorption process, different operational conditions were evaluated: adsorbent concentration (0.5 to 5.0 g/L), contact time (5 to 80 minutes), and application in sequential cycles. Increasing the activated carbon concentration from 0.5 to 3.0 g/L improved the removal efficiency of color and COD, reaching a maximum of 51% and 10%, respectively, while higher concentrations (4.0 and 5.0 g/L) showed no significant gains. Regarding contact time, no expressive improvements were observed above 5 minutes, which was defined as the optimum time for combining efficiency and operational simplicity. In sequential adsorption tests, the fractionation of 3.0 g/L into three cycles of 1.0 g/L was evaluated. However, no relevant increase in removal was observed compared to the direct application of 3.0 g/L. It was also observed that açaí seed biochar presented better efficiency in the removal of true color and COD. Based on this study and considering the low removal of color and especially COD, future studies are suggested to evaluate the effect of pH as well as the use of other adsorbent materials.

Síntese, caracterização e potencial atividade leismanicida do complexo [RuCl(BNT)(p-cym)]

2025-12-19T06:17:47Z

Title: Síntese, caracterização e potencial atividade leismanicida do complexo [RuCl(BNT)(p-cym)] Abstract: Ru(II)-based complexes have been investigated due to their chemical versatility and strong potential in pharmacological applications. In this work, the synthesis and spectroscopic characterization of the complex [RuCl(BNT)(ƞ⁶-p-cym)] were carried out, aiming at applications in in vitro studies for leishmanicidal activity. The complex [RuCl(BNT)(ƞ⁶-p-cym)] was synthesized from the precursor dimer [RuCl₂(ƞ⁶-p- cymene)]₂ and the ligand 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedionate (BNT). The geometry of the synthesized complex was suggested through spectroscopic techniques, such as infrared spectroscopy (ATR-FTIR), proton nuclear magnetic resonance (¹H NMR), mass spectrometry, ultraviolet-visible absorption spectroscopy (UV-Vis), and it was also subjected to antiparasitic activity assays. The ¹H NMR spectrum shows chemical shifts consistent with the expected values for the protons of the coordinated ligands. These signals appear deshielded compared to those of the free ligands due to the interaction with Ru(II), with special emphasis on the singlet of the β-diketonate at 6.4 ppm, which confirms its coordination to ruthenium(II). In addition, elemental analysis was performed to quantify the percentage of C and H, showing strong agreement between the experimental and theoretical values for the proposed structure. Mass spectrometry revealed an m/z value corresponding to the complex structure without the chloride ligand, as expected for this type of analysis. IR spectra were obtained for both the dimer and the complex, showing that, for the complex, the spectrum lacks the bridging Ru–Cl vibrational mode, evidencing its cleavage in the formation of the final complex. UV-Vis spectra also provided evidence of β-diketonate coordination. The compound exhibited activity against the promastigote form of L.(L.) amazonensis at the highest concentrations tested, while the precursor was inactive, indicating that the coordination of β-diketonates to [RuCl₂(ƞ⁶-p-cymene)]₂ represents an interesting strategy to generate compounds with leishmanicidal activity.

Novos derivados do azul de metileno como potenciais fotossensibilizadores para terapia fotodinâmica em câncer de mama triplo negativo.

2025-12-11T06:26:48Z

Title: Novos derivados do azul de metileno como potenciais fotossensibilizadores para terapia fotodinâmica em câncer de mama triplo negativo. Abstract: Triple-negative breast cancer is a highly aggressive subtype characterized by the absence of three receptors—estrogen (ER), progesterone (PR), and human epidermal growth factor receptor 2 (HER2)—which eliminates the possibility of conventional targeted therapies. In this context, Photodynamic Therapy (PDT) emerges as a promising alternative, provided that efficient photosensitizers (PS) are employed. This study evaluated the photophysical properties and biological activity of two novel methylene blue (MB) derivatives, AM-NMP, derivative in which one dimethylamino substituent is replaced by a naphthyl-methyl-piperazine group and AM-I (3-(dimethylamino)phenothiazin-5-ium chloride), against the triple-negative breast cancer cell line MDA-MB-231. Spectroscopic assays revealed that AM-NMP displayed a high molar absorptivity coefficient (ε ≈ 5.1 × 10⁴ L·mol⁻¹·cm⁻¹), whereas AM-I showed a significantly lower value (ε ≈ 1.0 × 10⁴ L·mol⁻¹·cm⁻¹), corresponding to nearly five-fold lower photon absorption efficiency. Both derivatives exhibited reduced fluorescence quantum yields (Φf) compared to MB (Φf = 0.04), with AM-NMP being about ten times lower (Φf = 0.0041) and AM-I about two times lower (Φf = 0.020). The singlet oxygen quantum yield (ΦΔ) was also low for both derivatives (≈ 0.021), in contrast with MB (0.52). Despite these limitations, both compounds showed good photostability up to 22 minutes of irradiation, ensuring adequate performance under the biological experimental conditions, which required only 12 minutes of light exposure. Cell viability assays demonstrated no dark cytotoxicity for any compound at the tested concentrations (0.1–10 µM) in MDA-MB-231 cells. Under red LED irradiation (λ = 633 nm, dose ≈ 5 J·cm⁻²), MB exhibited IC₅₀ ≈ 3.1 µM, AM-NMP ≈ 6.7 µM, while AM-I showed no phototoxicity (IC₅₀ > 10 µM). These results indicate that AM-NMP retains promising photoactivity (IC₅₀ < 10 µM), although less effective than MB, whereas AM-I proved inefficient for the proposed application. Overall, the structural modifications did not enhance PDT efficacy compared with methylene blue, but the findings provide important insights into structure–activity relationships and highlight future directions for optimization.