Binding of Gallic Acid and Epigallocatechin Gallate to Heat-Unfolded Whey Proteins at Neutral pH Alters Radical Scavenging Activity of in Vitro Protein Digests

Yanyun Cao; Youling L. Xiong

doi:10.1021/acs.jafc.7b03006

Binding of Gallic Acid and Epigallocatechin Gallate to Heat-Unfolded Whey Proteins at Neutral pH Alters Radical Scavenging Activity of in Vitro Protein Digests

Yanyun Cao, Youling L. Xiong

Animal and Food Sciences

Research output: Contribution to journal › Article › peer-review

36 Scopus citations

Abstract

Preheated (80 °C for 9 min) whey protein isolate (HWPI) was reacted with 20, 120, and 240 μmol/g (protein basis) gallic acid (GA) or epigallocatechin gallate (EGCG) at neutral pH and 25 °C. Isothermal titration calorimetry and fluorometry showed a similar trend that GA binding to HWPI was moderate but weaker than EGCG binding. However, the shift of maximal fluorescence emission wavelength in opposite directions in response to GA (blue) and EGCG (red) suggests discrepant binding patterns. Electrophoresis results showed that EGCG induced formation of HWPI complexes while GA only had a marginal effect. Both free and phenolic-bound HWPI exhibited mild antiradical activity. However, when subjected to in vitro digestion, synergistic radical-scavenging activity was produced between the phenolics and peptides with the highest synergism being observed on 120 μmol/g phenolics.

Original language	English
Pages (from-to)	8443-8450
Number of pages	8
Journal	Journal of Agricultural and Food Chemistry
Volume	65
Issue number	38
DOIs	https://doi.org/10.1021/acs.jafc.7b03006
State	Published - Sep 27 2017

Bibliographical note

Funding Information:
Article number 17-07-059 approved for publication by the Director of the Kentucky Agricultural Experiment Station. This research was supported by the USDA National Institute of Food and Agriculture (Hatch Project 1005724) and an Oversea Study Fellowship from the China Scholarship Council (to Y.C.). Notes The authors declare no competing financial interest.

Publisher Copyright:
© 2017 American Chemical Society.

Keywords

binding
heat-unfolded whey protein isolate
in vitro digestion
phenolic derivative
synergistic radical scavenging activity

ASJC Scopus subject areas

Chemistry (all)
Agricultural and Biological Sciences (all)

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title = "Binding of Gallic Acid and Epigallocatechin Gallate to Heat-Unfolded Whey Proteins at Neutral pH Alters Radical Scavenging Activity of in Vitro Protein Digests",

abstract = "Preheated (80 °C for 9 min) whey protein isolate (HWPI) was reacted with 20, 120, and 240 μmol/g (protein basis) gallic acid (GA) or epigallocatechin gallate (EGCG) at neutral pH and 25 °C. Isothermal titration calorimetry and fluorometry showed a similar trend that GA binding to HWPI was moderate but weaker than EGCG binding. However, the shift of maximal fluorescence emission wavelength in opposite directions in response to GA (blue) and EGCG (red) suggests discrepant binding patterns. Electrophoresis results showed that EGCG induced formation of HWPI complexes while GA only had a marginal effect. Both free and phenolic-bound HWPI exhibited mild antiradical activity. However, when subjected to in vitro digestion, synergistic radical-scavenging activity was produced between the phenolics and peptides with the highest synergism being observed on 120 μmol/g phenolics.",

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author = "Yanyun Cao and Xiong, {Youling L.}",

note = "Funding Information: Article number 17-07-059 approved for publication by the Director of the Kentucky Agricultural Experiment Station. This research was supported by the USDA National Institute of Food and Agriculture (Hatch Project 1005724) and an Oversea Study Fellowship from the China Scholarship Council (to Y.C.). Notes The authors declare no competing financial interest. Publisher Copyright: {\textcopyright} 2017 American Chemical Society.",

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AU - Xiong, Youling L.

N1 - Funding Information: Article number 17-07-059 approved for publication by the Director of the Kentucky Agricultural Experiment Station. This research was supported by the USDA National Institute of Food and Agriculture (Hatch Project 1005724) and an Oversea Study Fellowship from the China Scholarship Council (to Y.C.). Notes The authors declare no competing financial interest. Publisher Copyright: © 2017 American Chemical Society.

PY - 2017/9/27

Y1 - 2017/9/27

N2 - Preheated (80 °C for 9 min) whey protein isolate (HWPI) was reacted with 20, 120, and 240 μmol/g (protein basis) gallic acid (GA) or epigallocatechin gallate (EGCG) at neutral pH and 25 °C. Isothermal titration calorimetry and fluorometry showed a similar trend that GA binding to HWPI was moderate but weaker than EGCG binding. However, the shift of maximal fluorescence emission wavelength in opposite directions in response to GA (blue) and EGCG (red) suggests discrepant binding patterns. Electrophoresis results showed that EGCG induced formation of HWPI complexes while GA only had a marginal effect. Both free and phenolic-bound HWPI exhibited mild antiradical activity. However, when subjected to in vitro digestion, synergistic radical-scavenging activity was produced between the phenolics and peptides with the highest synergism being observed on 120 μmol/g phenolics.

AB - Preheated (80 °C for 9 min) whey protein isolate (HWPI) was reacted with 20, 120, and 240 μmol/g (protein basis) gallic acid (GA) or epigallocatechin gallate (EGCG) at neutral pH and 25 °C. Isothermal titration calorimetry and fluorometry showed a similar trend that GA binding to HWPI was moderate but weaker than EGCG binding. However, the shift of maximal fluorescence emission wavelength in opposite directions in response to GA (blue) and EGCG (red) suggests discrepant binding patterns. Electrophoresis results showed that EGCG induced formation of HWPI complexes while GA only had a marginal effect. Both free and phenolic-bound HWPI exhibited mild antiradical activity. However, when subjected to in vitro digestion, synergistic radical-scavenging activity was produced between the phenolics and peptides with the highest synergism being observed on 120 μmol/g phenolics.

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Binding of Gallic Acid and Epigallocatechin Gallate to Heat-Unfolded Whey Proteins at Neutral pH Alters Radical Scavenging Activity of in Vitro Protein Digests

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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