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The presence of pharmaceuticals in wastewater resulting from human activities has driven researchers to explore effective treatment methods such as adsorption using activated carbon (AC). While AC shows promise as an adsorbent, further studies are essential to comprehend its entire interaction with pharmaceuticals. This article investigates the adsorption of potassium diclofenac (PD) onto AC using experimental and modeling approaches. Batch adsorption studies coupled with Fourier transform infrared spectroscopy (FTIR) were employed to clarify the adsorption mechanism of PD on AC. Various kinetic and isotherm adsorption models were applied to analyze the adsorbent-adsorbate interaction. The kinetics were best described by Avrami's fractional order (AFO) nonlinear model. Also, the intraparticle diffusion (IP) model reveals a three-stage adsorption process. The experimental equilibrium data fitted well with the three-parameter nonlinear Liu model, indicating a maximum adsorption capacity (Qmax) of 88.45 mg g-1 and suggesting monolayer or multilayer adsorption. Thermodynamic analysis showed favorable adsorption (ΔG° < 0), with an enthalpy change (ΔH° = -30.85 kJ mol-1) characteristic of physisorption involving hydrogen bonds and π-π interactions. The adsorption mechanism was attributed to forming a double layer (adsorbate-adsorbent and adsorbate-adsorbate).

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The current investigation encompasses the structural planning, synthesis, and evaluation of the urease inhibitory activity of a series of molecular hybrids of hydroxamic acids and Michael acceptors, delineated from the structure of cinnamic acids. The synthesized compounds exhibited potent urease inhibitory effects, with IC50 values ranging from 3.8 to 12.8 µM. Kinetic experiments unveiled that the majority of the synthesized hybrids display characteristics of mixed inhibitors. Generally, derivatives containing electron-withdrawing groups on the aromatic ring demonstrate heightened activity, indicating that the increased electrophilicity of the beta carbon in the Michael Acceptor moiety positively influences the antiureolytic properties of this compounds class. Biophysical and theoretical investigations further corroborated the findings obtained from kinetic assays. These studies suggest that the hydroxamic acid core interacts with the urease active site, while the Michael acceptor moiety binds to one or more allosteric sites adjacent to the active site.

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In this paper, we evaluated the drug-receptor interactions responsible for the antimicrobial activity of thymol, the major compound present in the essential oil (EO) of Lippia thymoides (L. thymoides) Mart. & Schauer (Verbenaceae). It was previously reported that this EO exhibits antimicrobial activity against Candida albicans (C. albicans), Staphylococcus aureus (S. aureus), and Escherichia coli (E. coli). Therefore, we used molecular docking, molecular dynamics simulations, and free energy calculations to investigate the interaction of thymol with pharmacological receptors of interest to combat these pathogens. We found that thymol interacted favorably with the active sites of the microorganisms' molecular targets. MolDock Score results for systems formed with CYP51 (C. albicans), Dihydrofolate reductase (S. aureus), and Dihydropteroate synthase (E. coli) were -77.85, -67.53, and -60.88, respectively. Throughout the duration of the MD simulations, thymol continued interacting with the binding pocket of the molecular target of each microorganism. The van der Waals (ΔEvdW = -24.88, -26.44, -21.71 kcal/mol, respectively) and electrostatic interaction energies (ΔEele = -3.94, -11.07, -12.43 kcal/mol, respectively) and the nonpolar solvation energies (ΔGNP = -3.37, -3.25, -2.93 kcal/mol, respectively) were mainly responsible for the formation of complexes with CYP51 (C. albicans), Dihydrofolate reductase (S. aureus), and Dihydropteroate synthase (E. coli).

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The interaction between bovine serum albumin (BSA) and thimerosal (TM), an organomercury compound widely employed as a preservative in vaccines, was investigated simulating physiological conditions and using different spectroscopic techniques. The results, employing molecular fluorescence showed the interaction occurs by static quenching through electrostatic forces (ΔH < 0 and ΔS > 0), spontaneously (ΔG = -4.40 kJ mol-1) and with a binding constant of 3.24 × 103 M-1. Three-dimensional fluorescence studies indicated that TM causes structural changes in the polypeptide chain of the BSA, confirmed by circular dichroism that showed an increase in α-helix (from 43.9 to 47.8%) content after interaction process. Through synchronized fluorescence and employing bilirubin as a protein site marker, it was confirmed the preferential interaction of TM in the subdomain IB of BSA. The interaction mechanism proposed in this work is based on the reaction of TM with BSA through of free Cys34 residue, forming the adduct BSA-HgEt with the thiosalicylic acid release, which possibly interacts electrostatically with positive side chain amino acids of the modified protein. Finally, it was proven that both TM and EtHgCl accelerate the protein fibrillation kinetics in 42 and 122%, respectively, indicating the toxicity of these compounds in biological systems.

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The electrochemical behaviour of the cytosine nucleoside analogue and anti-cancer drug gemcitabine (GEM) was investigated at glassy carbon electrode, using cyclic, differential pulse and square wave voltammetry, in different pH supporting electrolytes, and no electrochemical redox process was observed. The evaluation of the interaction between GEM and DNA in incubated solutions and using the DNA-electrochemical biosensor was studied. The DNA structural modifications and damage were electrochemically detected following the changes in the oxidation peaks of guanosine and adenosine residues and the occurrence of the free guanine residues electrochemical signal. The DNA-GEM interaction mechanism occurred in two sequential steps. The initial process was independent of the DNA sequence and led to the condensation/aggregation of the DNA strands, producing rigid structures, which favoured a second step, in which the guanine hydrogen atoms, participating in the C-G base pair, interacted with the GEM ribose moiety fluorine atoms.

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Objetivo: realizar una revisión estructurada de la interacción warfarina y acetaminofén, buscando establecer su relevancia clínica y profundizar en el mecanismo de dicha interacción. Método: revisión estructurada en PubMed/Medline, de artículos en inglés y español, buscando los términos warfarin AND (acetaminophen OR paracetamol) en el título o resumen. La búsqueda se complementó con las referencias de artículos valorados como importantes. Los trabajos se agruparon en: relacionados con el aumento de sangrado por la interacción warfarina-acetaminofén, o relacionados con el mecanismo de la interacción. Resultados: se identificaron 45 artículos, de los cuales se incluyeron 15 en la revisión: 11 relacionados con el aumento del riesgo de sangrado por la interacción y cuatro con el mecanismo de la interacción. La gravedad del efecto (aumento de la probabilidad de sangrado) se consideró moderada; mientras que la probabilidad de aparición fue valorada como definida. Además, se identificó una relación entre la dosis de acetaminofén y el riesgo de sangrado. Por su parte, el N-acetil-para-benzoquinona-imina (metabolito del acetaminofén) inhibe enzimas del ciclo de la vitamina K y tiene un efecto sinérgico con el efecto anticoagulante de la warfarina. Conclusiones: la relevancia clínica de la interacción warfarina - acetaminofén es de riesgo alto, debido a que la gravedad del efecto (aumento del riesgo de sangrado) es moderada y su probabilidad de presentación es definida. Por tanto, estos dos medicamentos pueden ser utilizados conjuntamente, pero se debe realizar una estricta monitorización. El metabolito N-acetil-para-benzoquinona-imina es el responsable del aumento del efecto anticoagulante de la warfarina. (Acta Med Colomb 2013; 38: 22-27).

Objective: to make a structured review of the interaction between warfarin and acetaminophen, seeking to establish its clinical relevance and deepen in the mechanism of this interaction. Method: structured review of PubMed/Medline of articles in English and Spanish, looking warfarin and acetaminophen or paracetamol in the title or abstract. The search was complemented with references of articles rated as important. The papers were grouped in: related to increased bleeding due to warfarin-acetaminophen interaction, or related to the mechanism of the interaction. Results: we identified 45 articles, of which 15 were included in the review: 11 related to increased risk of bleeding due to the interaction and 4 with the mechanism of the interaction. The severity of the effect (increased likelihood of bleeding) was considered moderate, whereas the probability of appearance was rated as definite. In addition, we identified a relationship between the dose of acetaminophen and the risk of bleeding. In turn, the N-acetyl-para-benzoquinone-imine (metabolite of acetaminophen) inhibits enzymes of the vitamin K cycle and has a synergistic effect with the anticoagulant effect of warfarin. Conclusions: the clinical relevance of the interaction warfarin-acetaminophen is of high risk due to the fact that the severity of the effect (increased risk of bleeding) is moderate and the probability of its presentation is definite. Therefore, these two drugs can be used together, but a strict monitoring should be conducted. The metabolite N-acetyl-para-benzoquinone-imine is responsible for the increase in the anticoagulant effect of warfarin. (Acta Med Colomb 2013; 38: 22-27).

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