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Currently, acetylcholinesterase (AChE) inhibitors are the only anti-Alzheimer drugs commercially available. Despite their wide use those drugs are all dose dependent and their effect last for no longer than two years, with several side effects. The search of novel acetylcholinesterase (AChE) inhibitors remains as the main scientific route. Here we describe the synthesis, characterization, biological activity and an NMR binding-target study of a novel cis-[Ru(Bpy)2(EtPy)2]2+, (RuEtPy), Bpy = 2,2'-bipyridine and EtPy = 4,2-Ethylamino-pyridine) as a potential AChE inhibitor. The classic Ellman's colorimetric assay suggests that the RuEtPy exhibits a high inhibitory activity, following a competitive mechanism, with a remarkable low inhibition constant (Ki ≈ 16.8 µM), together with a IC50 = 39 µM. Hence, we have studied the spatial interactions for this novel candidate towards the human acetylcholinesterase (hAChE) using saturation transfer difference (STD)-NMR, in order to describe the mechanism of the interaction. NMR binding-target results shows that the 4,2-Ethylamino-Pyridine group is spatially closer to hAChE surface chemical arrangement than 2,2' bipyridine counterpart, exerting an efficient intermolecular interaction, with a low dissociation constant (KD ≈ 55 µM), probing that 4,2-Ethylamino-pyridine motif plays a key role in the inhibitory action.

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Resumen La estructura cristalina del compuesto ácido 2-E-((4-hidroxifenil) diazenil) benzoico se resolvió por medio del método de fase intrínseca usando datos de difracción de rayos X de monocristal, encontrando que la molécula cristaliza en el sistema cristalino ortorrómbico con grupo espacial Pbca. Dentro de su celda unidad hay cuatro moléculas por unidad asimétrica que son confórmeros moleculares. Estos confórmeros forman hélices beta a lo largo de la dirección [010]. A partir de los datos estructurales se realizó el cálculo de superficies de Hirshfeld determinando, a partir de ellas, sus correspondientes diagramas de huellas dactilares bidimensionales, lo que permitió estudiar las interacciones intermoleculares que más contribuyen al empaquetamiento cristalino. Así, se pudo determinar que la principal contribución a la superficie general está dada por los contactos H•••H (34,8%), seguida de interacciones O•••H/ H•••O (27%) y C•••H/H•••C (18,6%). También fueron calculadas las redes energéticas de interacción con un nivel de teoría DFT/B3LYP/6-31G(d,p), permitiendo cuantificar los valores de cada componente que aportan a la energía total, siendo las interacciones de dispersión (-57,5 kJ/mol) las que más contribuyen en la formación del empaquetamiento cristalino para este compuesto.

Abstract The crystalline structure of 2-E-((4-hydroxyphenyl) diazenil) benzoic acid compound was solved by intrinsic phase method using single-crystal X-ray diffraction data. The molecule crystallizes in the orthorhombic Pbca space group. in the unit cell four molecular conformers of the compound per asymmetric unit are observed, which are forming beta helix arrangement along [010] direction. Hirshfeld surface calculation was performed to determine the intermolecular interactions that contribute to the crystal packing. it was possible to observe that the main contribution to the general surface is given by the contacts H ••• H (34.8%), followed by interactions O ••• H/H ••• O (27%) and C ••• H/H ••• C (18.6%). The energy interaction networks were calculated at a DFT/B3LYP/6-31G(d,p) level, allowing to quantify the high participation of dispersion interactions (-57.5 kJ/mol) in the formation of crystal packing.

Resumo A estrutura cristalina do composto ácido 2-E-((4-hidroxifenil) diazenil) benzóico foi resolvida pelo método da fase intrínseca usando dados de difração de raios X de cristal único, constatando que a molécula cristaliza no sistema cristalino ortorrômbico com grupo espacial Pbca. Dentro de sua cela unitária, existem quatro moléculas por unidade assimétrica, que são isômeros moleculares. Esses isômeros formam hélices beta na direção [010]. A partir dos dados estruturais, foi realizado o cálculo das superfícies de Hirshfeld determinando a partir delas seus respetivos diagramas bidimensionais das impressões digitais, o que permitiu estudar as interações intermoleculares que mais contribuem para o empacotamento cristalino. Assim, foi determinado que a principal contribuição para a superfície geral é dada pelos contatos H ••• H (34,8%), seguidos pelas interações O ••• H / H••• O (27%) e C ••• H / H ••• C (18,6%). Também foram calculadas as redes de energia de interação com um nível de teoria DFT/B3LYP/6-31G(d,p), permitindo quantificar a alta participação de interações de dispersão (-57,5 kJ / mol) na formação do empacotamento cristalino para este composto.

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Alginate-based polyelectrolyte complexes (PECs) and hydrogel were engineered as platforms for local bevacizumab (BVZ) therapy. This study provides deep comprehension on the microstructures of such systems, and their correlation with drug-release patterns. PECs and hydrogel were characterized using Fourier transform infrared spectroscopy, small-angle X-ray scattering, scanning electron microscopy, atomic force microscopy, and porosimetry. Structural investigations indicated that PECs are formed by supramolecular interactions, resulting in physically cross-linked polymer networks, whereas the BVZ-loaded hydrogel has a more compact and rigid structure, promoting better entrapment of BVZ. PECs and hydrogel were able to control the BVZ release for 4 and 8 days, respectively. Their release profiles correlated best with the Higuchi and Korsmeyer-Peppas models, respectively, indicating drug diffusion as the limiting step for drug release. Furthermore, BVZ remained biologically active in vitro after its incorporation into the hydrogel system. Together, these studies confirm that PECs and hydrogel exhibit different porous structures and physicochemical properties, making them promising platforms that allow the modulation of BVZ release meeting different requirements.

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As part of the ongoing efforts in discovering potentially bioactive natural products from medicinal plants, the present study was conducted to isolate a new complex triterpenoid saponin from the barks of Albizia lebbeck. It was isolated by using chromatographic methods and its structural elucidation was performed using detailed analyses of 1H and 13C NMR spectra including 2D-NMR (COSY, TOCSY, HSQC and HMBC) spectroscopic techniques, high-resolution electrospray ionization mass spectrometry (HRESIMS) analysis and chemical conversions. Its structure was established as 21-[[(2E,6S)-6-[6-deoxy-4-O-[(2E,6S)-6-hydroxy-2-(hydroxymethyl)-6-methyl-1-oxo-2,7-octadienyl]-[(ß-d-glucopyranosyl)oxy]-2-(hydroxymethyl)-6-methyl-1-oxo-2,7-octadienyl]-[(ß-d-glucopyranosyl)oxy]-2,6-dimethyl-1-oxo-2,7-octadienyl]oxy]-16-hydroxy-3-[[O-ß-d-xylopyranosyl-(1 → 2)-O-α-l-arabinopyranosyl-(1 → 6)-2-(acetylamino)-2-deoxy-ß-d-glucopyranosyl]oxy]-(3ß,16α,21ß)-olean-12-en-28-oic acid O-α-l-arabinofuranosyl-(1 → 4)-O-[ß-d-glucopyranosyl-(1 → 3)]-O-6-deoxy-α-l-mannopyranosyl-(1 → 2)-ß-d-glucopyranosyl ester (1). Additionally, this study aimed to investigate the permeability property of 1, its activity on membrane integrity and supramolecular interactions with cellular constituents using in vitro experimental models.

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Anti-vascular endothelial growth factor (anti-VEGF) therapy applied to solid tumors is a promising strategy, yet, the challenge to deliver these agents at high drug concentrations together with the maintenance of therapeutic doses locally, at the tumor site, minimizes its benefits. To overcome these obstacles, we propose the development of a bevacizumab-loaded alginate hydrogel by electrostatic interactions to design a delivery system for controlled and anti-angiogenic therapy under tumor microenvironmental conditions. The tridimensional hydrogel structure produced provides drug stability and a system able to be introduced as a flowable solution, stablishing a depot after local administration. Biological performance by the chick embryo chorioallantoic membrane (CAM) assay indicated a pH-independent improved anti-angiogenic activity (∼50%) compared to commercial available anti-VEGF drug. Moreover, there was a considerable regression in tumor size when treated with this system. Immunohistochemistry highlighted a reduced number and disorganization of microscopic blood vessels resulting from applied therapy. These results suggest that the developed hydrogel is a promising approach to create an innovative delivery system that offers the possibility to treat different solid tumors by intratumoral administration.

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ß-Cyclodextrin (ß-CD)-grafted dextrans with spacer arms of different length were employed to evaluate the impact of supramolecular interactions on invertase activity. The modified dextrans were used as single additives or combined with trehalose in freeze-dried formulations containing invertase. Enzyme activity conservation was analyzed after freeze-drying and thermal treatment. The change of glass transition temperature (Tg ) was also evaluated and related to effective interactions. Outstanding differences on enzyme stability were mainly related to the effect of the spacer arm length on polymer-enzyme interactions, since both the degree of substitution and the molecular weight were similar for the two polymers. This change of effective interactions was also manifested in the pronounced reduction of Tg values, and were related to the chemical modification of the backbone during oxidation, and to the attachment of the ß-CD units with spacer arms of different length on dextran.

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