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Miklós Poór – One of the best experts on this subject based on the ideXlab platform.

  • Interactions of zearalanone, α-zearalanol, β-zearalanol, zearalenone-14-sulfate, and zearalenone-14-glucoside with serum albumin
    Mycotoxin Research, 2020
    Co-Authors: Zelma Faisal, Beáta Lemli, Sándor Kunsági-máté, Virág Vörös, Eszter Fliszár-nyúl, Miklós Poór
    Abstract:

    The xenoestrogenic mycotoxin zearalenone is a Fusarium -derived food and feed contaminant. In mammals, the reduced (e.g., zearalanone, α-zearalanol, and β-zearalanol) and conjugated (e.g., zearalenone-14-sulfate) metabolites of zearalenone are formed. Furthermore, filamentous fungi and plants are also able to convert zearalenone to conjugated derivatives, including zearalenone-14-sulfate and zearalenone-14-glucoside, respectively. Serum albumin is the dominant plasma protein in the circulation; it interacts with certain mycotoxins, affecting their toxicokinetics. In a previous investigation, we demonstrated the remarkable species differences regarding the albumin binding of zearalenone and zearalenols. In the current study, the interactions of zearalanone, α-zearalanol, β-zearalanol, zearalenone-14-sulfate, and zearalenone-14-glucoside with human, bovine, porcine, and rat serum Albumins were examined, employing fluorescence spectroscopy and affinity chromatography. Zearalanone, zearalanols, and zearalenone-14-sulfate form stable complexes with Albumins tested ( K = 9.3 × 10^3 to 8.5 × 10^5 L/mol), while the albumin binding of zearalenone-14-glucoside seems to be weak. Zearalenone-14-sulfate formed the most stable complexes with Albumins examined. Considerable species differences were observed in the albumin binding of zearalenone metabolites, which may have a role in the interspecies differences regarding the toxicity of zearalenone.

  • Interactions of zearalenone and its reduced metabolites α-zearalenol and β-zearalenol with serum Albumins: species differences, binding sites, and thermodynamics
    Mycotoxin Research, 2018
    Co-Authors: Zelma Faisal, Beáta Lemli, Sándor Kunsági-máté, Dénes Szerencsés, Mónika Bálint, Csaba Hetényi, Mónika Kuzma, Mátyás Mayer, Miklós Poór
    Abstract:

    Zearalenone (ZEN) is a mycotoxin produced by Fusarium species. ZEN mainly appears in cereals and related foodstuffs, causing reproductive disorders in animals, due to its xenoestrogenic effects. The main reduced metabolites of ZEN are α-zearalenol (α-ZEL) and β-zearalenol (β-ZEL). Similarly to ZEN, ZELs can also activate estrogen receptors; moreover, α-ZEL is the most potent endocrine disruptor among these three compounds. Serum albumin is the most abundant plasma protein in the circulation; it affects the tissue distribution and elimination of several drugs and xenobiotics. Although ZEN binds to albumin with high affinity, albumin-binding of α-ZEL and β-ZEL has not been investigated. In this study, the complex formation of ZEN, α-ZEL, and β-ZEL with human (HSA), bovine (BSA), porcine (PSA), and rat serum Albumins (RSA) was investigated by fluorescence spectroscopy, affinity chromatography, thermodynamic studies, and molecular modeling. Our main observations are as follows: (1) ZEN binds with higher affinity to Albumins than α-ZEL and β-ZEL. (2) The low binding affinity of β-ZEL toward albumin may result from its different binding position or binding site. (3) The binding constants of the mycotoxin-albumin complexes significantly vary with the species. (4) From the thermodynamic point of view, the formation of ZEN-HSA and ZEN-RSA complexes are similar, while the formation of ZEN-BSA and ZEN-PSA complexes are markedly different. These results suggest that the toxicological relevance of ZEN-albumin and ZEL-albumin interactions may also be species-dependent.

  • Fluorescence spectroscopic evaluation of the interactions of quercetin, isorhamnetin, and quercetin-3′-sulfate with different Albumins
    Journal of Luminescence, 2018
    Co-Authors: Miklós Poór, Gabriella Boda, Sándor Kunsági-máté, Paul W. Needs, Paul A. Kroon, Beáta Lemli
    Abstract:

    Abstract Quercetin is one of the most commonly occurring flavonoids in nature. Although, quercetin and its metabolites express negligible fluorescence, the albumin-bound form of quercetin has a strong fluorescence property. Considering the structural variance of different Albumins, we hypothesized that the fluorescence of albumin complexes of quercetin and its metabolites may vary significantly. Therefore, in this study the fluorescence enhancement of quercetin and some of its major metabolites in the presence of bovine (BSA), human (HSA), porcine (PSA), and rat serum Albumins (RSA) were investigated by steady-state fluorescence spectroscopy in PBS buffer (pH 7.4). Among the tested quercetin metabolites, significant fluorescence signal was shown by albumin complexes of quercetin, isorhamnetin, and quercetin-3′-sulfate, while other metabolites (tamarixetin, quercetin-3-glucuronide, and isorhamnetin-3-glucuronide) expressed negligible fluorescence. BSA was the most potent enhancer of quercetin-3′-sulfate but it showed poor effects regarding other flavonoids. The strongest enhancement of isorhamnetin was caused by HSA, while it was less effective enhancer of quercetin and quercetin-3′-sulfate. PSA showed a strong fluorescence enhancement of quercetin and quercetin-3′-sulfate but it was poorly effective regarding isorhamnetin. RSA was the most potent enhancer of quercetin but it caused only a weak enhancement of isorhamnetin and quercetin-3′-sulfate. Large changes of the pH (such as pH 5.0 and pH 10.0) almost completely abolished the fluorescence signals of the complexes. Nevertheless, slight decrease (pH 7.0) reduced and slight increase (pH 7.8) generally enhanced the fluorescence of flavonoid-albumin complexes (only exceptions were quercetin-PSA and quercetin-RSA). Complex formations were also investigated by fluorescence quenching studies. Based on our results, the formations of quercetin-BSA, quercetin-HSA, isorhamnetin-BSA, isorhamnetin-HSA, isorhamnetin-PSA, and quercetin-3′-sulfate – HSA complexes followed 1:1 stoichiometry, while the presence of a secondary binding site of flavonoids was assumed regarding other tested albumin complexes. Our study highlights that Albumins can induce significantly different fluorescence enhancement of flavonoids, and even the stoichiometry of flavonoid-albumin complexes may differ.

Beáta Lemli – One of the best experts on this subject based on the ideXlab platform.

  • Interactions of zearalanone, α-zearalanol, β-zearalanol, zearalenone-14-sulfate, and zearalenone-14-glucoside with serum albumin
    Mycotoxin Research, 2020
    Co-Authors: Zelma Faisal, Beáta Lemli, Sándor Kunsági-máté, Virág Vörös, Eszter Fliszár-nyúl, Miklós Poór
    Abstract:

    The xenoestrogenic mycotoxin zearalenone is a Fusarium -derived food and feed contaminant. In mammals, the reduced (e.g., zearalanone, α-zearalanol, and β-zearalanol) and conjugated (e.g., zearalenone-14-sulfate) metabolites of zearalenone are formed. Furthermore, filamentous fungi and plants are also able to convert zearalenone to conjugated derivatives, including zearalenone-14-sulfate and zearalenone-14-glucoside, respectively. Serum albumin is the dominant plasma protein in the circulation; it interacts with certain mycotoxins, affecting their toxicokinetics. In a previous investigation, we demonstrated the remarkable species differences regarding the albumin binding of zearalenone and zearalenols. In the current study, the interactions of zearalanone, α-zearalanol, β-zearalanol, zearalenone-14-sulfate, and zearalenone-14-glucoside with human, bovine, porcine, and rat serum Albumins were examined, employing fluorescence spectroscopy and affinity chromatography. Zearalanone, zearalanols, and zearalenone-14-sulfate form stable complexes with Albumins tested ( K = 9.3 × 10^3 to 8.5 × 10^5 L/mol), while the albumin binding of zearalenone-14-glucoside seems to be weak. Zearalenone-14-sulfate formed the most stable complexes with Albumins examined. Considerable species differences were observed in the albumin binding of zearalenone metabolites, which may have a role in the interspecies differences regarding the toxicity of zearalenone.

  • Interactions of zearalenone and its reduced metabolites α-zearalenol and β-zearalenol with serum Albumins: species differences, binding sites, and thermodynamics
    Mycotoxin Research, 2018
    Co-Authors: Zelma Faisal, Beáta Lemli, Sándor Kunsági-máté, Dénes Szerencsés, Mónika Bálint, Csaba Hetényi, Mónika Kuzma, Mátyás Mayer, Miklós Poór
    Abstract:

    Zearalenone (ZEN) is a mycotoxin produced by Fusarium species. ZEN mainly appears in cereals and related foodstuffs, causing reproductive disorders in animals, due to its xenoestrogenic effects. The main reduced metabolites of ZEN are α-zearalenol (α-ZEL) and β-zearalenol (β-ZEL). Similarly to ZEN, ZELs can also activate estrogen receptors; moreover, α-ZEL is the most potent endocrine disruptor among these three compounds. Serum albumin is the most abundant plasma protein in the circulation; it affects the tissue distribution and elimination of several drugs and xenobiotics. Although ZEN binds to albumin with high affinity, albumin-binding of α-ZEL and β-ZEL has not been investigated. In this study, the complex formation of ZEN, α-ZEL, and β-ZEL with human (HSA), bovine (BSA), porcine (PSA), and rat serum Albumins (RSA) was investigated by fluorescence spectroscopy, affinity chromatography, thermodynamic studies, and molecular modeling. Our main observations are as follows: (1) ZEN binds with higher affinity to Albumins than α-ZEL and β-ZEL. (2) The low binding affinity of β-ZEL toward albumin may result from its different binding position or binding site. (3) The binding constants of the mycotoxin-albumin complexes significantly vary with the species. (4) From the thermodynamic point of view, the formation of ZEN-HSA and ZEN-RSA complexes are similar, while the formation of ZEN-BSA and ZEN-PSA complexes are markedly different. These results suggest that the toxicological relevance of ZEN-albumin and ZEL-albumin interactions may also be species-dependent.

  • Fluorescence spectroscopic evaluation of the interactions of quercetin, isorhamnetin, and quercetin-3′-sulfate with different Albumins
    Journal of Luminescence, 2018
    Co-Authors: Miklós Poór, Gabriella Boda, Sándor Kunsági-máté, Paul W. Needs, Paul A. Kroon, Beáta Lemli
    Abstract:

    Abstract Quercetin is one of the most commonly occurring flavonoids in nature. Although, quercetin and its metabolites express negligible fluorescence, the albumin-bound form of quercetin has a strong fluorescence property. Considering the structural variance of different Albumins, we hypothesized that the fluorescence of albumin complexes of quercetin and its metabolites may vary significantly. Therefore, in this study the fluorescence enhancement of quercetin and some of its major metabolites in the presence of bovine (BSA), human (HSA), porcine (PSA), and rat serum Albumins (RSA) were investigated by steady-state fluorescence spectroscopy in PBS buffer (pH 7.4). Among the tested quercetin metabolites, significant fluorescence signal was shown by albumin complexes of quercetin, isorhamnetin, and quercetin-3′-sulfate, while other metabolites (tamarixetin, quercetin-3-glucuronide, and isorhamnetin-3-glucuronide) expressed negligible fluorescence. BSA was the most potent enhancer of quercetin-3′-sulfate but it showed poor effects regarding other flavonoids. The strongest enhancement of isorhamnetin was caused by HSA, while it was less effective enhancer of quercetin and quercetin-3′-sulfate. PSA showed a strong fluorescence enhancement of quercetin and quercetin-3′-sulfate but it was poorly effective regarding isorhamnetin. RSA was the most potent enhancer of quercetin but it caused only a weak enhancement of isorhamnetin and quercetin-3′-sulfate. Large changes of the pH (such as pH 5.0 and pH 10.0) almost completely abolished the fluorescence signals of the complexes. Nevertheless, slight decrease (pH 7.0) reduced and slight increase (pH 7.8) generally enhanced the fluorescence of flavonoid-albumin complexes (only exceptions were quercetin-PSA and quercetin-RSA). Complex formations were also investigated by fluorescence quenching studies. Based on our results, the formations of quercetin-BSA, quercetin-HSA, isorhamnetin-BSA, isorhamnetin-HSA, isorhamnetin-PSA, and quercetin-3′-sulfate – HSA complexes followed 1:1 stoichiometry, while the presence of a secondary binding site of flavonoids was assumed regarding other tested albumin complexes. Our study highlights that Albumins can induce significantly different fluorescence enhancement of flavonoids, and even the stoichiometry of flavonoid-albumin complexes may differ.

Sándor Kunsági-máté – One of the best experts on this subject based on the ideXlab platform.

  • Interactions of zearalanone, α-zearalanol, β-zearalanol, zearalenone-14-sulfate, and zearalenone-14-glucoside with serum albumin
    Mycotoxin Research, 2020
    Co-Authors: Zelma Faisal, Beáta Lemli, Sándor Kunsági-máté, Virág Vörös, Eszter Fliszár-nyúl, Miklós Poór
    Abstract:

    The xenoestrogenic mycotoxin zearalenone is a Fusarium -derived food and feed contaminant. In mammals, the reduced (e.g., zearalanone, α-zearalanol, and β-zearalanol) and conjugated (e.g., zearalenone-14-sulfate) metabolites of zearalenone are formed. Furthermore, filamentous fungi and plants are also able to convert zearalenone to conjugated derivatives, including zearalenone-14-sulfate and zearalenone-14-glucoside, respectively. Serum albumin is the dominant plasma protein in the circulation; it interacts with certain mycotoxins, affecting their toxicokinetics. In a previous investigation, we demonstrated the remarkable species differences regarding the albumin binding of zearalenone and zearalenols. In the current study, the interactions of zearalanone, α-zearalanol, β-zearalanol, zearalenone-14-sulfate, and zearalenone-14-glucoside with human, bovine, porcine, and rat serum Albumins were examined, employing fluorescence spectroscopy and affinity chromatography. Zearalanone, zearalanols, and zearalenone-14-sulfate form stable complexes with Albumins tested ( K = 9.3 × 10^3 to 8.5 × 10^5 L/mol), while the albumin binding of zearalenone-14-glucoside seems to be weak. Zearalenone-14-sulfate formed the most stable complexes with Albumins examined. Considerable species differences were observed in the albumin binding of zearalenone metabolites, which may have a role in the interspecies differences regarding the toxicity of zearalenone.

  • Interactions of zearalenone and its reduced metabolites α-zearalenol and β-zearalenol with serum Albumins: species differences, binding sites, and thermodynamics
    Mycotoxin Research, 2018
    Co-Authors: Zelma Faisal, Beáta Lemli, Sándor Kunsági-máté, Dénes Szerencsés, Mónika Bálint, Csaba Hetényi, Mónika Kuzma, Mátyás Mayer, Miklós Poór
    Abstract:

    Zearalenone (ZEN) is a mycotoxin produced by Fusarium species. ZEN mainly appears in cereals and related foodstuffs, causing reproductive disorders in animals, due to its xenoestrogenic effects. The main reduced metabolites of ZEN are α-zearalenol (α-ZEL) and β-zearalenol (β-ZEL). Similarly to ZEN, ZELs can also activate estrogen receptors; moreover, α-ZEL is the most potent endocrine disruptor among these three compounds. Serum albumin is the most abundant plasma protein in the circulation; it affects the tissue distribution and elimination of several drugs and xenobiotics. Although ZEN binds to albumin with high affinity, albumin-binding of α-ZEL and β-ZEL has not been investigated. In this study, the complex formation of ZEN, α-ZEL, and β-ZEL with human (HSA), bovine (BSA), porcine (PSA), and rat serum Albumins (RSA) was investigated by fluorescence spectroscopy, affinity chromatography, thermodynamic studies, and molecular modeling. Our main observations are as follows: (1) ZEN binds with higher affinity to Albumins than α-ZEL and β-ZEL. (2) The low binding affinity of β-ZEL toward albumin may result from its different binding position or binding site. (3) The binding constants of the mycotoxin-albumin complexes significantly vary with the species. (4) From the thermodynamic point of view, the formation of ZEN-HSA and ZEN-RSA complexes are similar, while the formation of ZEN-BSA and ZEN-PSA complexes are markedly different. These results suggest that the toxicological relevance of ZEN-albumin and ZEL-albumin interactions may also be species-dependent.

  • Fluorescence spectroscopic evaluation of the interactions of quercetin, isorhamnetin, and quercetin-3′-sulfate with different Albumins
    Journal of Luminescence, 2018
    Co-Authors: Miklós Poór, Gabriella Boda, Sándor Kunsági-máté, Paul W. Needs, Paul A. Kroon, Beáta Lemli
    Abstract:

    Abstract Quercetin is one of the most commonly occurring flavonoids in nature. Although, quercetin and its metabolites express negligible fluorescence, the albumin-bound form of quercetin has a strong fluorescence property. Considering the structural variance of different Albumins, we hypothesized that the fluorescence of albumin complexes of quercetin and its metabolites may vary significantly. Therefore, in this study the fluorescence enhancement of quercetin and some of its major metabolites in the presence of bovine (BSA), human (HSA), porcine (PSA), and rat serum Albumins (RSA) were investigated by steady-state fluorescence spectroscopy in PBS buffer (pH 7.4). Among the tested quercetin metabolites, significant fluorescence signal was shown by albumin complexes of quercetin, isorhamnetin, and quercetin-3′-sulfate, while other metabolites (tamarixetin, quercetin-3-glucuronide, and isorhamnetin-3-glucuronide) expressed negligible fluorescence. BSA was the most potent enhancer of quercetin-3′-sulfate but it showed poor effects regarding other flavonoids. The strongest enhancement of isorhamnetin was caused by HSA, while it was less effective enhancer of quercetin and quercetin-3′-sulfate. PSA showed a strong fluorescence enhancement of quercetin and quercetin-3′-sulfate but it was poorly effective regarding isorhamnetin. RSA was the most potent enhancer of quercetin but it caused only a weak enhancement of isorhamnetin and quercetin-3′-sulfate. Large changes of the pH (such as pH 5.0 and pH 10.0) almost completely abolished the fluorescence signals of the complexes. Nevertheless, slight decrease (pH 7.0) reduced and slight increase (pH 7.8) generally enhanced the fluorescence of flavonoid-albumin complexes (only exceptions were quercetin-PSA and quercetin-RSA). Complex formations were also investigated by fluorescence quenching studies. Based on our results, the formations of quercetin-BSA, quercetin-HSA, isorhamnetin-BSA, isorhamnetin-HSA, isorhamnetin-PSA, and quercetin-3′-sulfate – HSA complexes followed 1:1 stoichiometry, while the presence of a secondary binding site of flavonoids was assumed regarding other tested albumin complexes. Our study highlights that Albumins can induce significantly different fluorescence enhancement of flavonoids, and even the stoichiometry of flavonoid-albumin complexes may differ.

Paul A. Kroon – One of the best experts on this subject based on the ideXlab platform.

  • Fluorescence spectroscopic evaluation of the interactions of quercetin, isorhamnetin, and quercetin-3′-sulfate with different Albumins
    Journal of Luminescence, 2018
    Co-Authors: Miklós Poór, Gabriella Boda, Sándor Kunsági-máté, Paul W. Needs, Paul A. Kroon, Beáta Lemli
    Abstract:

    Abstract Quercetin is one of the most commonly occurring flavonoids in nature. Although, quercetin and its metabolites express negligible fluorescence, the albumin-bound form of quercetin has a strong fluorescence property. Considering the structural variance of different Albumins, we hypothesized that the fluorescence of albumin complexes of quercetin and its metabolites may vary significantly. Therefore, in this study the fluorescence enhancement of quercetin and some of its major metabolites in the presence of bovine (BSA), human (HSA), porcine (PSA), and rat serum Albumins (RSA) were investigated by steady-state fluorescence spectroscopy in PBS buffer (pH 7.4). Among the tested quercetin metabolites, significant fluorescence signal was shown by albumin complexes of quercetin, isorhamnetin, and quercetin-3′-sulfate, while other metabolites (tamarixetin, quercetin-3-glucuronide, and isorhamnetin-3-glucuronide) expressed negligible fluorescence. BSA was the most potent enhancer of quercetin-3′-sulfate but it showed poor effects regarding other flavonoids. The strongest enhancement of isorhamnetin was caused by HSA, while it was less effective enhancer of quercetin and quercetin-3′-sulfate. PSA showed a strong fluorescence enhancement of quercetin and quercetin-3′-sulfate but it was poorly effective regarding isorhamnetin. RSA was the most potent enhancer of quercetin but it caused only a weak enhancement of isorhamnetin and quercetin-3′-sulfate. Large changes of the pH (such as pH 5.0 and pH 10.0) almost completely abolished the fluorescence signals of the complexes. Nevertheless, slight decrease (pH 7.0) reduced and slight increase (pH 7.8) generally enhanced the fluorescence of flavonoid-albumin complexes (only exceptions were quercetin-PSA and quercetin-RSA). Complex formations were also investigated by fluorescence quenching studies. Based on our results, the formations of quercetin-BSA, quercetin-HSA, isorhamnetin-BSA, isorhamnetin-HSA, isorhamnetin-PSA, and quercetin-3′-sulfate – HSA complexes followed 1:1 stoichiometry, while the presence of a secondary binding site of flavonoids was assumed regarding other tested albumin complexes. Our study highlights that Albumins can induce significantly different fluorescence enhancement of flavonoids, and even the stoichiometry of flavonoid-albumin complexes may differ.

  • fluorescence spectroscopic evaluation of the interactions of quercetin isorhamnetin and quercetin 3 sulfate with different Albumins
    Journal of Luminescence, 2018
    Co-Authors: Miklós Poór, Gabriella Boda, Paul W. Needs, Paul A. Kroon, Sandor Kunsagimate, Beáta Lemli
    Abstract:

    Abstract Quercetin is one of the most commonly occurring flavonoids in nature. Although, quercetin and its metabolites express negligible fluorescence, the albumin-bound form of quercetin has a strong fluorescence property. Considering the structural variance of different Albumins, we hypothesized that the fluorescence of albumin complexes of quercetin and its metabolites may vary significantly. Therefore, in this study the fluorescence enhancement of quercetin and some of its major metabolites in the presence of bovine (BSA), human (HSA), porcine (PSA), and rat serum Albumins (RSA) were investigated by steady-state fluorescence spectroscopy in PBS buffer (pH 7.4). Among the tested quercetin metabolites, significant fluorescence signal was shown by albumin complexes of quercetin, isorhamnetin, and quercetin-3′-sulfate, while other metabolites (tamarixetin, quercetin-3-glucuronide, and isorhamnetin-3-glucuronide) expressed negligible fluorescence. BSA was the most potent enhancer of quercetin-3′-sulfate but it showed poor effects regarding other flavonoids. The strongest enhancement of isorhamnetin was caused by HSA, while it was less effective enhancer of quercetin and quercetin-3′-sulfate. PSA showed a strong fluorescence enhancement of quercetin and quercetin-3′-sulfate but it was poorly effective regarding isorhamnetin. RSA was the most potent enhancer of quercetin but it caused only a weak enhancement of isorhamnetin and quercetin-3′-sulfate. Large changes of the pH (such as pH 5.0 and pH 10.0) almost completely abolished the fluorescence signals of the complexes. Nevertheless, slight decrease (pH 7.0) reduced and slight increase (pH 7.8) generally enhanced the fluorescence of flavonoid-albumin complexes (only exceptions were quercetin-PSA and quercetin-RSA). Complex formations were also investigated by fluorescence quenching studies. Based on our results, the formations of quercetin-BSA, quercetin-HSA, isorhamnetin-BSA, isorhamnetin-HSA, isorhamnetin-PSA, and quercetin-3′-sulfate – HSA complexes followed 1:1 stoichiometry, while the presence of a secondary binding site of flavonoids was assumed regarding other tested albumin complexes. Our study highlights that Albumins can induce significantly different fluorescence enhancement of flavonoids, and even the stoichiometry of flavonoid-albumin complexes may differ.

Paul W. Needs – One of the best experts on this subject based on the ideXlab platform.

  • Fluorescence spectroscopic evaluation of the interactions of quercetin, isorhamnetin, and quercetin-3′-sulfate with different Albumins
    Journal of Luminescence, 2018
    Co-Authors: Miklós Poór, Gabriella Boda, Sándor Kunsági-máté, Paul W. Needs, Paul A. Kroon, Beáta Lemli
    Abstract:

    Abstract Quercetin is one of the most commonly occurring flavonoids in nature. Although, quercetin and its metabolites express negligible fluorescence, the albumin-bound form of quercetin has a strong fluorescence property. Considering the structural variance of different Albumins, we hypothesized that the fluorescence of albumin complexes of quercetin and its metabolites may vary significantly. Therefore, in this study the fluorescence enhancement of quercetin and some of its major metabolites in the presence of bovine (BSA), human (HSA), porcine (PSA), and rat serum Albumins (RSA) were investigated by steady-state fluorescence spectroscopy in PBS buffer (pH 7.4). Among the tested quercetin metabolites, significant fluorescence signal was shown by albumin complexes of quercetin, isorhamnetin, and quercetin-3′-sulfate, while other metabolites (tamarixetin, quercetin-3-glucuronide, and isorhamnetin-3-glucuronide) expressed negligible fluorescence. BSA was the most potent enhancer of quercetin-3′-sulfate but it showed poor effects regarding other flavonoids. The strongest enhancement of isorhamnetin was caused by HSA, while it was less effective enhancer of quercetin and quercetin-3′-sulfate. PSA showed a strong fluorescence enhancement of quercetin and quercetin-3′-sulfate but it was poorly effective regarding isorhamnetin. RSA was the most potent enhancer of quercetin but it caused only a weak enhancement of isorhamnetin and quercetin-3′-sulfate. Large changes of the pH (such as pH 5.0 and pH 10.0) almost completely abolished the fluorescence signals of the complexes. Nevertheless, slight decrease (pH 7.0) reduced and slight increase (pH 7.8) generally enhanced the fluorescence of flavonoid-albumin complexes (only exceptions were quercetin-PSA and quercetin-RSA). Complex formations were also investigated by fluorescence quenching studies. Based on our results, the formations of quercetin-BSA, quercetin-HSA, isorhamnetin-BSA, isorhamnetin-HSA, isorhamnetin-PSA, and quercetin-3′-sulfate – HSA complexes followed 1:1 stoichiometry, while the presence of a secondary binding site of flavonoids was assumed regarding other tested albumin complexes. Our study highlights that Albumins can induce significantly different fluorescence enhancement of flavonoids, and even the stoichiometry of flavonoid-albumin complexes may differ.

  • fluorescence spectroscopic evaluation of the interactions of quercetin isorhamnetin and quercetin 3 sulfate with different Albumins
    Journal of Luminescence, 2018
    Co-Authors: Miklós Poór, Gabriella Boda, Paul W. Needs, Paul A. Kroon, Sandor Kunsagimate, Beáta Lemli
    Abstract:

    Abstract Quercetin is one of the most commonly occurring flavonoids in nature. Although, quercetin and its metabolites express negligible fluorescence, the albumin-bound form of quercetin has a strong fluorescence property. Considering the structural variance of different Albumins, we hypothesized that the fluorescence of albumin complexes of quercetin and its metabolites may vary significantly. Therefore, in this study the fluorescence enhancement of quercetin and some of its major metabolites in the presence of bovine (BSA), human (HSA), porcine (PSA), and rat serum Albumins (RSA) were investigated by steady-state fluorescence spectroscopy in PBS buffer (pH 7.4). Among the tested quercetin metabolites, significant fluorescence signal was shown by albumin complexes of quercetin, isorhamnetin, and quercetin-3′-sulfate, while other metabolites (tamarixetin, quercetin-3-glucuronide, and isorhamnetin-3-glucuronide) expressed negligible fluorescence. BSA was the most potent enhancer of quercetin-3′-sulfate but it showed poor effects regarding other flavonoids. The strongest enhancement of isorhamnetin was caused by HSA, while it was less effective enhancer of quercetin and quercetin-3′-sulfate. PSA showed a strong fluorescence enhancement of quercetin and quercetin-3′-sulfate but it was poorly effective regarding isorhamnetin. RSA was the most potent enhancer of quercetin but it caused only a weak enhancement of isorhamnetin and quercetin-3′-sulfate. Large changes of the pH (such as pH 5.0 and pH 10.0) almost completely abolished the fluorescence signals of the complexes. Nevertheless, slight decrease (pH 7.0) reduced and slight increase (pH 7.8) generally enhanced the fluorescence of flavonoid-albumin complexes (only exceptions were quercetin-PSA and quercetin-RSA). Complex formations were also investigated by fluorescence quenching studies. Based on our results, the formations of quercetin-BSA, quercetin-HSA, isorhamnetin-BSA, isorhamnetin-HSA, isorhamnetin-PSA, and quercetin-3′-sulfate – HSA complexes followed 1:1 stoichiometry, while the presence of a secondary binding site of flavonoids was assumed regarding other tested albumin complexes. Our study highlights that Albumins can induce significantly different fluorescence enhancement of flavonoids, and even the stoichiometry of flavonoid-albumin complexes may differ.