Examinando por Autor "Caballero, Julio"
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Ítem Dammarane triterpenes targeting α-synuclein: biological activity and evaluation of binding sites by molecular docking(Taylor and Francis Ltd., 2021) Cornejo, Alberto; Caballero, Julio; Simirgiotis, Mario; Torres, Vanessa; Sánchez, Luisa; Díaz, Nicolás; Guimaraes, Marcela; Hernández, Marcos; Areche, Carlos; Alfaro, Sergio; Caballero, Leonardo; Melo, FranciscoParkinson's disease (PD) is a neurodegenerative disorder that affects adult people whose treatment is palliative. Thus, we decided to test three dammarane triterpenes 1, 1a, 1b, and we determined that 1 and 1a inhibit β-aggregation through thioflavine T rather than 1b. Since compound 1 was most active, we determined the interaction between α-synuclein and 1 at 50 µM (Kd) through microscale thermophoresis. Also, we observed differences in height and diameter of aggregates, and α-synuclein remains unfolded in the presence of 1. Also, aggregates treated with 1 do not provoke neurites' retraction in N2a cells previously induced by retinoic acid. Finally, we studied the potential sites of interaction between 1 with α-synuclein fibrils using molecular modelling. Docking experiments suggest that 1 preferably interact with the site 2 of α-synuclein through hydrogen bonds with residues Y39 and T44.Ítem Insights into the interactions between maleimide derivates and GSK3β combining molecular docking and QSAR(Public Library of Science, 2014-07) Quesada-Romero, Luisa; Mena-Ulecia, Karel; Tiznado, William; Caballero, JulioMany protein kinase (PK) inhibitors have been reported in recent years, but only a few have been approved for clinical use. The understanding of the available molecular information using computational tools is an alternative to contribute to this process. With this in mind, we studied the binding modes of 77 maleimide derivates inside the PK glycogen synthase kinase 3 beta (GSK3b) using docking experiments. We found that the orientations that these compounds adopt inside GSK3b binding site prioritize the formation of hydrogen bond (HB) interactions between the maleimide group and the residues at the hinge region (residues Val135 and Asp133), and adopt propeller-like conformations (where the maleimide is the propeller axis and the heterocyclic substituents are two slanted blades). In addition, quantitative structure–activity relationship (QSAR) models using CoMSIA methodology were constructed to explain the trend of the GSK3b inhibitory activities for the studied compounds. We found a model to explain the structure–activity relationship of non-cyclic maleimide (NCM) derivatives (54 compounds). The best CoMSIA model (training set included 44 compounds) included steric, hydrophobic, and HB donor fields and had a good Q2 value of 0.539. It also predicted adequately the most active compounds contained in the test set. Furthermore, the analysis of the plots of the steric CoMSIA field describes the elements involved in the differential potency of the inhibitors that can be considered for the selection of suitable inhibitors.Ítem Multicomponent synthesis and photophysical study of novel α,β-unsaturated carbonyl depsipeptides and peptoids(Frontiers Media SA, 2023) González, Ricelia; Murillo-López, Juliana; Rabanal-León, Walter; Prent-Peñaloza, Luis; Concepción, Odette; Olivares, Pedro; Duarte, Yorley; de la Torre, Alexander F.; Gutiérrez, Margarita; Caballero, JulioMulticomponent reactions were performed to develop novel α,β-unsaturated carbonyl depsipeptides and peptoids incorporating various chromophores such as cinnamic, coumarin, and quinolines. Thus, through the Passerini and Ugi multicomponent reactions (P-3CR and U-4CR), we obtained thirteen depsipeptides and peptoids in moderate to high yield following the established protocol and fundamentally varying the electron-rich carboxylic acid as reactants. UV/Vis spectroscopy was utilized to study the photophysical properties of the newly synthesized compounds. Differences between the carbonyl-substituted chromophores cause differences in electron delocalization that can be captured in the spectra. The near UV regions of all the compounds exhibited strong absorption bands. Compounds P2, P5, U2, U5, and U7 displayed absorption bands in the range of 250–350 nm, absorbing radiation in this broad region of the electromagnetic spectrum. A photostability study for U5 showed that its molecular structure does not change after exposure to UV radiation. Fluorescence analysis showed an incipient emission of U5, while U6 showed blue fluorescence under UV radiation. The photophysical properties and electronic structure were also determined by TD-DFT theoretical study. Copyright © 2023 González, Murillo-López, Rabanal-León, Prent-Peñaloza, Concepción, Olivares, Duarte, de la Torre, Gutiérrez and Caballero.Ítem Rosmarinic acid prevents fibrillization and diminishes vibrational modes associated to β sheet in tau protein linked to Alzheimer’s disease(Journal of Enzyme Inhibition and Medicinal Chemistry, 2017-01) Cornejo, Alberto; Aguilar Sandoval, Felipe; Caballero, Leonardo; Machuca, Luis; Muñoz, Patricio; Caballero, Julio; Perry, George; Ardiles, Alejandro; Areche, Carlos; Melo, FranciscoAlzheimer’s disease is a common tauopathy where fibril formation and aggregates are the hallmark of the disease. Efforts targeting amyloid-β plaques have succeeded to remove plaques but failed in clinical trials to improve cognition; thus, the current therapeutic strategy is at preventing tau aggregation. Here, we demonstrated that four phenolic diterpenoids and rosmarinic acid inhibit fibrillization. Since, rosmarinic acid was the most active compound, we observe morphological changes in atomic force microscopy images after treatment. Hence, rosmarinic acid leads to a decrease in amide regions I and III, indicating that rosmarinic acid prevents β-sheet assembly. Molecular docking study inside the steric zipper model of the hexapeptide 306VQIVYK311 involved in fibrillization and β sheet formation, suggests that rosmarinic acid binds to the steric zipper with similar chemical interactions with respect to those observed for orange G, a known pharmacofore for amyloid. © 2017 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.Ítem Structural Requirements of N-alpha-Mercaptoacetyl Dipeptide (NAMdP) Inhibitors of Pseudomonas Aeruginosa Virulence Factor LasB: 3D-QSAR, Molecular Docking, and Interaction Fingerprint Studies(MDPI AG, 2019-12) Velázquez-Libera, José Luis; Murillo-López, Juliana Andrea; de la Torre, Alexander F.; Caballero, JulioThe zinc metallopeptidase Pseudomonas elastase (LasB) is a virulence factor of Pseudomonas aeruginosa (P. aeruginosa), a pathogenic bacterium that can cause nosocomial infections. The present study relates the structural analysis of 118 N-alpha-mercaptoacetyl dipeptides (NAMdPs) as LasB inhibitors. Field-based 3D-QSAR and molecular docking methods were employed to describe the essential interactions between NAMdPs and LasB binding sites, and the chemical features that determine their differential activities. We report a predictive 3D-QSAR model that was developed according to the internal and external validation tests. The best model, including steric, electrostatic, hydrogen bond donor, hydrogen bond acceptor, and hydrophobic fields, was found to depict a three-dimensional map with the local positive and negative effects of these chemotypes on the LasB inhibitory activities. Furthermore, molecular docking experiments yielded bioactive conformations of NAMdPs inside the LasB binding site. The series of NAMdPs adopted a similar orientation with respect to phosphoramidon within the LasB binding site (crystallographic reference), where the backbone atoms of NAMdPs are hydrogen-bonded to the LasB residues N112, A113, and R198, similarly to phosphoramidon. Our study also included a deep description of the residues involved in the protein–ligand interaction patterns for the whole set of NAMdPs, through the use of interaction fingerprints (IFPs). © 2019 by the authors. Licensee MDPI, Basel, Switzerland.Ítem Study of the affinity between the protein kinase PKA and peptide substrates derived from kemptide using molecular dynamics simulations and MM/GBSA(Public Library of Science, 2014) Mena-Ulecia, Karel; Vergara-Jaque, Ariela; Poblete, Horacio; Tiznado, William; Caballero, JulioWe have carried out a protocol in computational biochemistry including molecular dynamics (MD) simulations and MM/GBSA free energy calculations on the complex between the protein kinase A (PKA) and the specific peptide substrate Kemptide (LRRASLG). We made the same calculations on other PKA complexes that contain Kemptide derivatives (with mutations of the arginines, and with deletions of N and C-terminal amino acids). We predicted shifts in the free energy changes from the free PKA to PKA-substrate complex (δδGE→ES) when Kemptide structure is modified (we consider that the calculated shifts correlate with the experimental shifts of the free energy changes from the free PKA to the transition states (δδGE→TS) determined by the catalytic efficiency (kcat/KM) changes). Our results demonstrate that it is possible to predict the kinetic properties of protein kinases using simple computational biochemistry methods. As an additional benefit, these methods give detailed molecular information that permit the analysis of the atomic forces that contribute to the affinity between protein kinases and their substrates. © 2014 Mena-Ulecia et al.