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Silver nanoparticles (AgNP) have gained significant attention due to their unique pharmacological properties. These nanoparticles have been found to possess antimicrobial, anti-inflammatory, and antioxidant activities, making them promising candidates for various medical applications. The coating characteristics of oxcarbazepine (OXC), a drug used in epilepsy treatment, on the AgNP icosahedral clusters were investigated using molecular dynamics (MD) simulations and noncovalent interactions (NCI) and Independent Gradient Model (IGM) analysis. We investigated the AgNP coating using OXC drug concentrations of 500, 1000, 1500, 2000, and 2500 ppm. Our results suggested that the OXC drug has a high potential interaction with the AgNP, especially when the concentration increases. Furthermore, it was observed that this interaction occurs mainly through the nitrogen atom (N 1 ) of the OXC molecule, independent of concentration. Finally, the coating is more pronounced for high OXC concentrations. The weak interaction analysis indicated that the van der Waals interactions were observed between the OXC molecules and AgNP, resulting in relevant stability in these interactions. Therefore, our study may be helpful for experimental research groups to develop an oxcarbazepine drug delivery system using AgNP., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Flavor esters are organic compounds widely used in the food industry to enhance the aroma and taste of products. However, most chemical processes for the production of these flavoring compounds use toxic organic solvents. Some organic solvents derived from petroleum can leave behind residual traces in food products, which may raise concerns about potential health risks and contamination. In this study, we employ Eversa Transform 2.0, a commercial lipase derived from the lipase from Thermomyces lanuginosus , to produce geranyl butyrate in aqueous media. The chemical process was optimized using the Taguchi method, and a conversion of 93% was obtained at the optimal reaction conditions of: 1:5 molar ratio (v/v), 15% biocatalyst load (w/w), at 50 °C, in 6 h. Classic (molecular dynamics) and quantum (density functional theory) simulations unveiled amino acid residues involved in the stabilization of the enzyme-substrate complex. Detailed QM/MM mechanistic studies identified the nucleophilic attack of the deacylation reaction as the rate-limiting step of the entire mechanism, which has a free energy barrier of 14.0 kcal/mol., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

The acidity of organic compounds is highly relevant to understanding several biological processes. Although the relevance and challenges in estimating pK a values of organic acids is recognized by several reported works in the literature, there is a lack in determining the acidity of amides. This paper presents an experimental/theoretical combined investigation on the acid dissociation of the compound 6,7-dinitro-1,4-dihydroquinoxaline-2,3-dione (DNQX), a well-established antagonist of ionotropic glutamate receptor GluA2. DNQX was synthesized, and its two acidic constants were determined by UV-vis spectroscopy. The experimental pK a of 6.99 ± 0.02 and 10.57 ± 0.01 indicate that DNQX mainly exists as an anionic form (DNQXA1) in physiological media, which was also confirmed by 1 H NMR analysis. Five computational methods were applied for estimating the theoretical pK a values of DNQX, including B3LYP, M06-2X, ωB97XD, and CBS-QB3, which were able to provide reasonable estimates for pK a associated with DNQX. Molecular dynamics studies have demonstrated that DNQXA1' binds more effectively to the pocket of the GluA2 than neutral DNQX, and this fact is coherent to the interactions between amidic oxygens and Arg845 being the main interactions of this host-guest system. Moreover, interaction of GluA2 with endogenous glutamate is stronger than that with DNQXA1, which is in agreement with literature. To the best of our knowledge, we report herein an unprecedented approach involving acidity of the antagonist DNQX, as well as the possible implications in binding to GluA2.