Estudio de la influencia de la estructura del anillo B de flavonoles en sus constantes de acidez y capacidad antioxidante
Four flavonols namely: Quercetin, Morin, Kaempferol and Myricetin were studied using spectrophotometry UV/Vis, in aqueous solution. The study was performed varying the pH to analyze the stability of these compounds, and to estimate their acidity constants. In addition, the deprotonation mechanisms w...
| Autor: | |
|---|---|
| Formato: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2014 |
| País: | México |
| Recursos: | Universidad Autónoma Metropolitana |
| Repositorio: | Repositorio Institucional de la UAM Iztapalapa |
| Idioma: | español |
| OAI Identifier: | oai:bindani.izt.uam.mx:gm80hv44c |
| Acesso em linha: | https://doi.org/10.24275/uami.gm80hv44c |
| Access Level: | acceso abierto |
| Palavra-chave: | info:eu-repo/classification/LEM/Free radicals (Chemistry) info:eu-repo/classification/LEM/Oxidation info:eu-repo/classification/LEM/Antioxidants info:eu-repo/classification/LEM/Radicales libres (Química) info:eu-repo/classification/LEM/Antioxidantes info:eu-repo/classification/LEM/Flavonoides -- Efectos fisiológicos info:eu-repo/classification/LEM/Oxidación info:eu-repo/classification/LEM/Chemistry info:eu-repo/classification/LEM/Química info:eu-repo/classification/LEM/Flavonoids -- Physiological effect info:eu-repo/classification/LEM/Polyphenols info:eu-repo/classification/cti/2 |
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Estudio de la influencia de la estructura del anillo B de flavonoles en sus constantes de acidez y capacidad antioxidante |
| title |
Estudio de la influencia de la estructura del anillo B de flavonoles en sus constantes de acidez y capacidad antioxidante |
| spellingShingle |
Estudio de la influencia de la estructura del anillo B de flavonoles en sus constantes de acidez y capacidad antioxidante RUSLAN RAULIEVICH ALVAREZ DIDUK info:eu-repo/classification/LEM/Free radicals (Chemistry) info:eu-repo/classification/LEM/Oxidation info:eu-repo/classification/LEM/Antioxidants info:eu-repo/classification/LEM/Radicales libres (Química) info:eu-repo/classification/LEM/Antioxidantes info:eu-repo/classification/LEM/Flavonoides -- Efectos fisiológicos info:eu-repo/classification/LEM/Oxidación info:eu-repo/classification/LEM/Chemistry info:eu-repo/classification/LEM/Química info:eu-repo/classification/LEM/Flavonoids -- Physiological effect info:eu-repo/classification/LEM/Polyphenols info:eu-repo/classification/cti/2 |
| title_short |
Estudio de la influencia de la estructura del anillo B de flavonoles en sus constantes de acidez y capacidad antioxidante |
| title_full |
Estudio de la influencia de la estructura del anillo B de flavonoles en sus constantes de acidez y capacidad antioxidante |
| title_fullStr |
Estudio de la influencia de la estructura del anillo B de flavonoles en sus constantes de acidez y capacidad antioxidante |
| title_full_unstemmed |
Estudio de la influencia de la estructura del anillo B de flavonoles en sus constantes de acidez y capacidad antioxidante |
| title_sort |
Estudio de la influencia de la estructura del anillo B de flavonoles en sus constantes de acidez y capacidad antioxidante |
| dc.creator.none.fl_str_mv |
RUSLAN RAULIEVICH ALVAREZ DIDUK |
| author |
RUSLAN RAULIEVICH ALVAREZ DIDUK |
| author_facet |
RUSLAN RAULIEVICH ALVAREZ DIDUK |
| author_role |
author |
| dc.contributor.none.fl_str_mv |
Arben Merkoçi MARIA TERESA RAMIREZ SILVA |
| dc.subject.none.fl_str_mv |
info:eu-repo/classification/LEM/Free radicals (Chemistry) info:eu-repo/classification/LEM/Oxidation info:eu-repo/classification/LEM/Antioxidants info:eu-repo/classification/LEM/Radicales libres (Química) info:eu-repo/classification/LEM/Antioxidantes info:eu-repo/classification/LEM/Flavonoides -- Efectos fisiológicos info:eu-repo/classification/LEM/Oxidación info:eu-repo/classification/LEM/Chemistry info:eu-repo/classification/LEM/Química info:eu-repo/classification/LEM/Flavonoids -- Physiological effect info:eu-repo/classification/LEM/Polyphenols info:eu-repo/classification/cti/2 |
| topic |
info:eu-repo/classification/LEM/Free radicals (Chemistry) info:eu-repo/classification/LEM/Oxidation info:eu-repo/classification/LEM/Antioxidants info:eu-repo/classification/LEM/Radicales libres (Química) info:eu-repo/classification/LEM/Antioxidantes info:eu-repo/classification/LEM/Flavonoides -- Efectos fisiológicos info:eu-repo/classification/LEM/Oxidación info:eu-repo/classification/LEM/Chemistry info:eu-repo/classification/LEM/Química info:eu-repo/classification/LEM/Flavonoids -- Physiological effect info:eu-repo/classification/LEM/Polyphenols info:eu-repo/classification/cti/2 |
| description |
Four flavonols namely: Quercetin, Morin, Kaempferol and Myricetin were studied using spectrophotometry UV/Vis, in aqueous solution. The study was performed varying the pH to analyze the stability of these compounds, and to estimate their acidity constants. In addition, the deprotonation mechanisms were studied using computational chemistry, within the Density Functional Theory framework. The calculations were performed in aqueous solution using the SMD continuum model and the results are reported as deprotonation energies. Our results show that both quercetin and myricetin are highly unstable at basic pH. Kaempferol, on the other hand, is much more stable; and morin is the only one, among the studied compounds, that was not affected by pH. In spite of this inconvenience, their acidity constants were estimated through analysis of their decomposition kinetics, correcting the spectra accordingly, and obtaining a correlation of values between the experimentally observed pKa and the calculated ∆G of successive deprotonations. On the other hand cadmium sulfide nanocrystals where synthesized and characterized using TEM. A fluorescence quenching of these nanoparticles was observed in the presence of flavonoids. This allows proposing a high selective method of determination for this kind of compounds. The percentage of inhibition depends on the structure of the compound and might be related to their antioxidant activity. The antioxidant capacity was estimated using the traditional DPPH method. The results indicate that Myricetin is the most reactive among all the studied flavonoids. Furthermore, regeneration of the catechol group in methanol was postulated. In addition computational calculations were also employed to estimate the antioxidant activity, considering different reaction mechanisms and reactions with the OOH radical. For the electron transfer mechanism the obtained trend is similar to that arising from the DPPH assay. However the predominant mechanism for the hydroperoxyl radical scavenging activity of these compounds is the hydrogen transfer. Morin was found to be the most reactive of the studied compounds via H transfer, with rate constant within the diffusion-limited regime. This methodology demonstrates the importance of considering the molar fraction of the chemical species at a fixed pH. |
| publishDate |
2014 |
| dc.date.none.fl_str_mv |
2014-08 |
| dc.type.none.fl_str_mv |
info:eu-repo/semantics/doctoralThesis info:eu-repo/semantics/publishedVersion |
| format |
doctoralThesis |
| status_str |
publishedVersion |
| dc.identifier.none.fl_str_mv |
https://doi.org/10.24275/uami.gm80hv44c |
| url |
https://doi.org/10.24275/uami.gm80hv44c |
| dc.language.none.fl_str_mv |
spa |
| language |
spa |
| dc.rights.none.fl_str_mv |
info:eu-repo/semantics/openAccess https://creativecommons.org/licenses/by-nc/4.0/ |
| eu_rights_str_mv |
openAccess |
| rights_invalid_str_mv |
https://creativecommons.org/licenses/by-nc/4.0/ |
| dc.source.none.fl_str_mv |
reponame:Repositorio Institucional de la UAM Iztapalapa instname:Universidad Autónoma Metropolitana instacron:UAM |
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Universidad Autónoma Metropolitana |
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UAM |
| institution |
UAM |
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Repositorio Institucional de la UAM Iztapalapa |
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Repositorio Institucional de la UAM Iztapalapa |
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| _version_ |
1858177322544267264 |
| spelling |
Estudio de la influencia de la estructura del anillo B de flavonoles en sus constantes de acidez y capacidad antioxidanteRUSLAN RAULIEVICH ALVAREZ DIDUKinfo:eu-repo/classification/LEM/Free radicals (Chemistry)info:eu-repo/classification/LEM/Oxidationinfo:eu-repo/classification/LEM/Antioxidantsinfo:eu-repo/classification/LEM/Radicales libres (Química)info:eu-repo/classification/LEM/Antioxidantesinfo:eu-repo/classification/LEM/Flavonoides -- Efectos fisiológicosinfo:eu-repo/classification/LEM/Oxidacióninfo:eu-repo/classification/LEM/Chemistryinfo:eu-repo/classification/LEM/Químicainfo:eu-repo/classification/LEM/Flavonoids -- Physiological effectinfo:eu-repo/classification/LEM/Polyphenolsinfo:eu-repo/classification/cti/2Four flavonols namely: Quercetin, Morin, Kaempferol and Myricetin were studied using spectrophotometry UV/Vis, in aqueous solution. The study was performed varying the pH to analyze the stability of these compounds, and to estimate their acidity constants. In addition, the deprotonation mechanisms were studied using computational chemistry, within the Density Functional Theory framework. The calculations were performed in aqueous solution using the SMD continuum model and the results are reported as deprotonation energies. Our results show that both quercetin and myricetin are highly unstable at basic pH. Kaempferol, on the other hand, is much more stable; and morin is the only one, among the studied compounds, that was not affected by pH. In spite of this inconvenience, their acidity constants were estimated through analysis of their decomposition kinetics, correcting the spectra accordingly, and obtaining a correlation of values between the experimentally observed pKa and the calculated ∆G of successive deprotonations. On the other hand cadmium sulfide nanocrystals where synthesized and characterized using TEM. A fluorescence quenching of these nanoparticles was observed in the presence of flavonoids. This allows proposing a high selective method of determination for this kind of compounds. The percentage of inhibition depends on the structure of the compound and might be related to their antioxidant activity. The antioxidant capacity was estimated using the traditional DPPH method. The results indicate that Myricetin is the most reactive among all the studied flavonoids. Furthermore, regeneration of the catechol group in methanol was postulated. In addition computational calculations were also employed to estimate the antioxidant activity, considering different reaction mechanisms and reactions with the OOH radical. For the electron transfer mechanism the obtained trend is similar to that arising from the DPPH assay. However the predominant mechanism for the hydroperoxyl radical scavenging activity of these compounds is the hydrogen transfer. Morin was found to be the most reactive of the studied compounds via H transfer, with rate constant within the diffusion-limited regime. This methodology demonstrates the importance of considering the molar fraction of the chemical species at a fixed pH.Cuatro flavonoles: Quercetina, Morina, Kaempferol y Miricetina con características estructurales similares pero con diferente número y posición de grupos OH en uno de sus anillos (anillo B) fueron estudiados con el fin de determinar su estabilidad, constantes de acidez, el orden de desprotonación y su actividad antioxidante en solución acuosa. Para analizar la estabilidad de estos compuestos y determinar las constantes de acidez se empleó espectrofotometría UV-Vis a diferentes valores de pH. Los mecanismos de desprotonación fueron calculados con la ayuda de la química computacional, usando la Teoría de los Funcionales de la Densidad. Los cálculos se realizaron en solución acuosa utilizando el modelo continuo SMD y los resultados fueron reportados como energías de desprotonación. Los resultados muestran que tanto la Quercetina como la Miricetina son altamente inestables a valores de pH básico. El Kaempferol, por otro lado, es mucho más estable y la Morina es el único entre los compuestos estudiados, que no se vio afectado por el valor de pH. A pesar de este inconveniente, sus constantes de acidez se estimaron mediante el análisis de su cinética de descomposición y se propone como consecuencia la corrección de los espectros. Se obtiene una correlación entre los valores de pKa y los observados experimentalmente y el ∆G calculado de las desprotonaciones sucesivas. Por otra parte se sintetizaron nanocristales de sulfuro de cadmio, se caracterizaron usando TEM y se observa como los flavonoles inhiben la fluorescencia de estas nanopartículas, proponiéndose así un método de determinación, selectivo a flavonoles. El porcentaje de inhibición depende de la estructura del compuesto y podría relacionarse con la actividad antioxidante. Por último se determinó la capacidad antioxidante usando el método del DPPH donde los resultados indican que la Miricetina es la más reactiva. Además se evidencia la regeneración del grupo catecol en Metanol. También se emplearon cálculos computacionales considerando todos los posibles mecanismos de reacción frente al radical OOH● donde se demuestra la importancia de considerar todos los posibles mecanismos de reacción y las fracciones molares de las especies a un determinado valor de pH, se analizó el mecanismo de transferencia electrónica donde la Miricetina sigue siendo la más reactiva. No obstante el mecanismo predominante frente al radical estudiado es el de transferencia de Hidrógeno obteniéndose que la Morina es la más reactiva por esta vía con una constante de velocidad limitada por difusión.Arben MerkoçiMARIA TERESA RAMIREZ SILVA2014-08info:eu-repo/semantics/doctoralThesisinfo:eu-repo/semantics/publishedVersionhttps://doi.org/10.24275/uami.gm80hv44creponame:Repositorio Institucional de la UAM Iztapalapainstname:Universidad Autónoma Metropolitanainstacron:UAMspainfo:eu-repo/semantics/openAccesshttps://creativecommons.org/licenses/by-nc/4.0/oai:bindani.izt.uam.mx:gm80hv44c2025-11-26T19:19:46Z |
| score |
15.812429 |