OLIVARES, MARIA BELEN
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OLIVARES, MARIA BELEN
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molivares@udd.cl
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57194227842

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Material Suplementario - Kinetics and Reaction Mechanism of Biothiols Involved in SNAr Reactions: An Experimental Study

2022 , CAMPODONICO GALDAMES, PAOLA ROSSANA , OLIVARES, MARIA BELEN

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Innate gut microbiota predisposes to high alcohol consumption

2021 , EZQUER, EDUARDO FERNANDO , Maria Elena Quintanilla , Francisco Moya‐Flores , Paola Morales , MUNITA SEPULVEDA, JOSE MANUEL , OLIVARES, MARIA BELEN , Glauben Landskron , Marcela A. Hermoso , EZQUER, EDUARDO MARCELO , Mario Herrera‐Marschitz , Yedy Israel

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Kinetics and Reaction Mechanism of Biothiols Involved in SNAr Reactions: An Experimental Study

2022 , CAMPODONICO GALDAMES, PAOLA ROSSANA , Jazmín Alarcón-Espósito , OLIVARES, MARIA BELEN

Few kinetic parameters, or reaction rates, are known up to date in detail about 1-chloro and 1-fluoro-2,4-dinitrobenzene (ClDNB and FDNB, respectively) with a series of biothiols in aqueous media. These biological nucleophiles with thiol groups have been widely used as a reference in nucleophile reactivity assays due to their prevalence and cellular abundance. The main aim of this study was to elucidate the reaction mechanism based on Brönsted-type plots and reactivity patterns of the electrophile/nucleophile pairs. A complete kinetic study was performed in terms of the comparison of Brönsted-type slope parameters (βnuc) for the reactions and was used for assigning the mechanism and the rate-determining step associated with the reaction route. A mass spectrometry analysis demonstrated that the nucleophilic center of the biothiols is the -SH group and there is only one kinetic product. The kinetic study suggests that the reaction mechanism might be the borderline between concerted and stepwise pathways. An amine–enol equilibrium for the most reactive nucleophiles appears to be the main determining factor controlling the nucleophilic attack in the nucleophilic aromatic substitution reactions investigated, highlighting the anionic form for these nucleophiles. This amine–enol equilibrium involves a hydrogen bond which stabilizes the intermediate species in the reaction pathway. Thus, intramolecular bonds are formed and enhance the nucleophilic strength through the contribution of the solvent surrounding the electrophile/nucleophile pairs. Finally, we highlight the importance of the formation of electrophile/nucleophile adducts that could modify structures and/or functions of biological systems with potential toxic effects. Therefore, it is essential to know all these kinetic and reactivity patterns and their incidence on other studies.

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Analysis of the Behavior of Deep Eutectic Solvents upon Addition of Water: Its Effects over a Catalytic Reaction

2024 , CAMPODONICO GALDAMES, PAOLA ROSSANA , Jazmín Alarcón-Espósito , ALCAZAR JIMENEZ, JACKSON JOSE , OLIVARES, MARIA BELEN , SUAREZ ROZAS, CRISTIAN IGNACIO

This study presents the potential role of deep eutectic solvents (DESs) in a lipase-catalyzed hydrolysis reaction as a co-solvent in an aqueous solution given by a phosphate buffer. Ammonium salts, such as choline chloride, were paired with hydrogen bond donors, such as urea, 1,2,3-propanetriol, and 1,2 propanediol. The hydrolysis of p-nitrophenyl laureate was carried out with the lipase Candida antarctica Lipase B (CALB) as a reaction model to evaluate the solvent effect and tested in different DES/buffer phosphate mixtures at different % w/w. The results showed that two mixtures of different DES at 25 % w/w were the most promising solvents, as this percentage enhanced the activities of CALB, as evidenced by its higher catalytic efficiency (kcatKM). The solvent analysis shows that the enzymatic reaction requires a reaction media rich in water molecules to enable hydrogen-bond formation from the reaction media toward the enzymatic reaction, suggesting a better interaction between the substrate and the enzyme-active site. This interaction could be attributed to high degrees of freedom influencing the enzyme conformation given by the reaction media, suggesting that CALB acquires a more restrictive structure in the presence of DES or the stabilized network given by the hydrogen bond from water molecules in the mixture improves the enzymatic activity, conferring conformational stability by solvent effects. This study offers a promising approach for applications and further perspectives on genuinely green industrial solvents.

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Exploring the behavior of Candida antarctica lipase B in aqueous mixtures of an imidazolium ionic liquid and its surfactant analogue

2023 , CAMPODONICO GALDAMES, PAOLA ROSSANA , Cristian Calderón , Jackson J. Alcázar , OLIVARES, MARIA BELEN , Limberg Jaldin , Cristian Suárez-Rozas

The performance of Candida antarctica lipase B (CALB) has been evaluated in 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4)/water mixtures in a wide range of molar fractions (χBMIMBF4) with and without 1-dodecyl-3-methylimidazolium tetrafluoroborate (C12-MIMBF4), a surfactant derived from BMIMBF4. The main aim of this work is to evaluate the influence of χBMIMBF4 over micellar aggregates to assess the activity of enzymatic reactions. The investigated reaction corresponds to the hydrolysis of the substrate p-nitrophenyl laureate in each χBMIMBF4. The kinetic study for χBMIMBF4 at around 0.2 proved to be a border point in enzymatic activity. At χBMIMBF4 = 0.1, the lipase activity increases in the presence of C12-MIMBF4. However, at higher concentrations, BMIMBF4 has a negligible effect over the lipase activity. These results suggest specific interactions between water and BMIMBF4 molecules in relation to CALB. This research highlights the superactivity phenomenon driven by the reaction media and the micelle interface. In this interfacial interaction, BMIMBF4 acts directly on the changes induced on the enzyme upon its interaction with the micellar interface. This study opens a green perspective toward the biocatalysis field.

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Experimental Analyses Emphasize the Stability of the Meisenheimer Complex in a SNAr Reaction Toward Trends in Reaction Pathways

2020 , CAMPODONICO GALDAMES, PAOLA ROSSANA , OLIVARES, MARIA BELEN , Ricardo A. Tapia

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A Natural deep eutectic solvent as an effective material for dual debridement and antibiofilm effects in chronic wound treatment

2024 , SCHUH, CHRISTINA , EZQUER, EDUARDO FERNANDO , MAMANI FLORES, SIGDE KARINA , CAMPODONICO GALDAMES, PAOLA ROSSANA , Constanza Cárcamo , Fabián Martinez-Gómez , Isabel Aburto , EZQUER, EDUARDO MARCELO , Bernardo Morales , OLIVARES, MARIA BELEN

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Chronic Voluntary Morphine Intake Is Associated with Changes in Brain Structures Involved in Drug Dependence in a Rat Model of Polydrug Use

2023 , María Elena Quintanilla , Paola Morales , Daniela Santapau , Alba Ávila , Carolina Ponce , BERRIOS CARCAMO, PABLO ANDRES , OLIVARES, MARIA BELEN , Mario Herrera-Marschitz , EZQUER, EDUARDO MARCELO , Javiera Gallardo , Yedy Israel , EZQUER, EDUARDO FERNANDO

Chronic opioid intake leads to several brain changes involved in the development of dependence, whereby an early hedonistic effect (liking) extends to the need to self-administer the drug (wanting), the latter being mostly a prefrontal–striatal function. The development of animal models for voluntary oral opioid intake represents an important tool for identifying the cellular and molecular alterations induced by chronic opioid use. Studies mainly in humans have shown that polydrug use and drug dependence are shared across various substances. We hypothesize that an animal bred for its alcohol preference would develop opioid dependence and further that this would be associated with the overt cortical abnormalities clinically described for opioid addicts. We show that Wistar-derived outbred UChB rats selected for their high alcohol preference additionally develop: (i) a preference for oral ingestion of morphine over water, resulting in morphine intake of 15 mg/kg/day; (ii) marked opioid dependence, as evidenced by the generation of strong withdrawal signs upon naloxone administration; (iii) prefrontal cortex alterations known to be associated with the loss of control over drug intake, namely, demyelination, axonal degeneration, and a reduction in glutamate transporter GLT-1 levels; and (iv) glial striatal neuroinflammation and brain oxidative stress, as previously reported for chronic alcohol and chronic nicotine use. These findings underline the relevance of polydrug animal models and their potential in the study of the wide spectrum of brain alterations induced by chronic morphine intake. This study should be valuable for future evaluations of therapeutic approaches for this devastating condition.

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Aloe vera peel-derived nanovesicles display anti-inflammatory properties and prevent myofibroblast differentiation

2024 , RAMIREZ PRADA, ORLANDO JOSUÉ , Florencia Pomareda , OLIVARES, MARIA BELEN , HUANG, YA LIN , Gabriela Zavala , Javiera Carrasco-Rojas , Simón Alvarez , Camila Leiva-Sabadini , Valeria Hidalgo , Pablo Romo , SANCHEZ JIMÉNEZ, MATÍAS IGNACIO , Ayleen Vargas , Sebastian Aguayo , SCHUH, CHRISTINA , MARTINEZ ARENAS, JESSICA ISABEL

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Aspirin and N‐acetylcysteine co‐administration markedly inhibit chronic ethanol intake and block relapse binge drinking: Role of neuroinflammation‐oxidative stress self‐perpetuation

2019 , Yedy Israel , María Elena Quintanilla , EZQUER, EDUARDO FERNANDO , Paola Morales , Daniela Santapau , BERRIOS CARCAMO, PABLO ANDRES , EZQUER, EDUARDO MARCELO , OLIVARES, MARIA BELEN , Mario Herrera‐Marschitz

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