OLIVARES, MARIA BELEN

Preferred name
OLIVARES, MARIA BELEN
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Email
molivares@udd.cl
ORCID
0000-0001-6950-8433
Scopus Author ID
57194227842
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      18Scopus© Citations 65
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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  
    <jats:p>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 (<jats:italic>β</jats:italic><jats:sub>nuc</jats:sub>) 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.</jats:p>
      1Scopus© Citations 2
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      1Scopus© Citations 27
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    NK-Extrusomes: Artificial Cell-Derived Vesicles (ACDV), An Alternative Nanodrug Delivery System for Lung Cancer
    (2025)
    CARRASCO, JAVIERA
    ;
    ORLANDO JOSUE RAMIREZ PRADA
    ;
    GABRIELA ZAVALA VIVAR
    ;
    RAFAEL ALEXANDER CONTRERAS LÓPEZ
    ;
    FELIPE I. SANDOVAL
      5
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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
    <jats:p>The performance of <jats:italic>Candida antarctica</jats:italic> lipase B (CALB) has been evaluated in 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF<jats:sub>4</jats:sub>)/water mixtures in a wide range of molar fractions (<jats:inline-formula><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m1"><mml:mrow><mml:msub><mml:mi mathvariant="normal">χ</mml:mi><mml:mrow><mml:mi>B</mml:mi><mml:mi>M</mml:mi><mml:mi>I</mml:mi><mml:mi>M</mml:mi><mml:mi>B</mml:mi><mml:mi>F</mml:mi><mml:mn>4</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math></jats:inline-formula>) with and without 1-dodecyl-3-methylimidazolium tetrafluoroborate (C<jats:sub>12</jats:sub>-MIMBF<jats:sub>4</jats:sub>), a surfactant derived from BMIMBF<jats:sub>4</jats:sub>. The main aim of this work is to evaluate the influence of <jats:inline-formula><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m2"><mml:mrow><mml:msub><mml:mi mathvariant="normal">χ</mml:mi><mml:mrow><mml:mi>B</mml:mi><mml:mi>M</mml:mi><mml:mi>I</mml:mi><mml:mi>M</mml:mi><mml:mi>B</mml:mi><mml:mi>F</mml:mi><mml:mn>4</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math></jats:inline-formula> over micellar aggregates to assess the activity of enzymatic reactions. The investigated reaction corresponds to the hydrolysis of the substrate <jats:italic>p</jats:italic>-nitrophenyl laureate in each <jats:inline-formula><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m3"><mml:mrow><mml:msub><mml:mi mathvariant="normal">χ</mml:mi><mml:mrow><mml:mi>B</mml:mi><mml:mi>M</mml:mi><mml:mi>I</mml:mi><mml:mi>M</mml:mi><mml:mi>B</mml:mi><mml:mi>F</mml:mi><mml:mn>4</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math></jats:inline-formula>. The kinetic study for <jats:inline-formula><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m4"><mml:mrow><mml:msub><mml:mi mathvariant="normal">χ</mml:mi><mml:mrow><mml:mi>B</mml:mi><mml:mi>M</mml:mi><mml:mi>I</mml:mi><mml:mi>M</mml:mi><mml:mi>B</mml:mi><mml:mi>F</mml:mi><mml:mn>4</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math></jats:inline-formula> at around 0.2 proved to be a border point in enzymatic activity. At <jats:inline-formula><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m5"><mml:mrow><mml:msub><mml:mi mathvariant="normal">χ</mml:mi><mml:mrow><mml:mi>B</mml:mi><mml:mi>M</mml:mi><mml:mi>I</mml:mi><mml:mi>M</mml:mi><mml:mi>B</mml:mi><mml:mi>F</mml:mi><mml:mn>4</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math></jats:inline-formula> = 0.1, the lipase activity increases in the presence of C<jats:sub>12</jats:sub>-MIMBF<jats:sub>4</jats:sub>. However, at higher concentrations, BMIMBF<jats:sub>4</jats:sub> has a negligible effect over the lipase activity. These results suggest specific interactions between water and BMIMBF<jats:sub>4</jats:sub> molecules in relation to CALB. This research highlights the superactivity phenomenon driven by the reaction media and the micelle interface. In this interfacial interaction, BMIMBF<jats:sub>4</jats:sub> 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.</jats:p>
      12Scopus© Citations 4
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    A Novel Morphine Drinking Model of Opioid Dependence in Rats
    (2022)
    BERRIOS CARCAMO, PABLO ANDRES  
    ;
    Mauricio Quezada
    ;
    Daniela Santapau
    ;
    Paola Morales
    ;
    OLIVARES, MARIA BELEN  
    <jats:p>An animal model of voluntary oral morphine consumption would allow for a pre-clinical evaluation of new treatments aimed at reducing opioid intake in humans. However, the main limitation of oral morphine consumption in rodents is its bitter taste, which is strongly aversive. Taste aversion is often overcome by the use of adulterants, such as sweeteners, to conceal morphine taste or bitterants in the alternative bottle to equalize aversion. However, the adulterants’ presence is the cause for consumption choice and, upon removal, the preference for morphine is not preserved. Thus, current animal models are not suitable to study treatments aimed at reducing consumption elicited by morphine itself. Since taste preference is a learned behavior, just-weaned rats were trained to accept a bitter taste, adding the bitterant quinine to their drinking water for one week. The latter was followed by allowing the choice of quinine or morphine (0.15 mg/mL) solutions for two weeks. Then, quinine was removed, and the preference for morphine against water was evaluated. Using this paradigm, we show that rats highly preferred the consumption of morphine over water, reaching a voluntary morphine intake of 15 mg/kg/day. Morphine consumption led to significant analgesia and hyperlocomotion, and to a marked deprivation syndrome following the administration of the opioid antagonist naloxone. Voluntary morphine consumption was also shown to generate brain oxidative stress and neuroinflammation, signs associated with opioid dependence development. We present a robust two-bottle choice animal model of oral morphine self-administration for the evaluation of therapeutic interventions for the treatment of morphine dependence.</jats:p>
      1Scopus© Citations 18
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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  
      5Scopus© Citations 34
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      2Scopus© Citations 36