Protein Adducts and Protein Oxidation as Molecular Mechanisms of Flavonoid Bioactivity

There are tens of thousands of scientific papers about flavonoids and their impacts on human health. However, despite the vast amount of energy that has been put toward studying these compounds, a unified molecular mechanism that explains their bioactivity remains elusive. One contributing factor to...

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Main Author: P. Matthew Joyner
Format: Article
Language:English
Published: MDPI AG 2021-08-01
Series:Molecules
Subjects:
Online Access:https://www.mdpi.com/1420-3049/26/16/5102
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author P. Matthew Joyner
author_facet P. Matthew Joyner
author_sort P. Matthew Joyner
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description There are tens of thousands of scientific papers about flavonoids and their impacts on human health. However, despite the vast amount of energy that has been put toward studying these compounds, a unified molecular mechanism that explains their bioactivity remains elusive. One contributing factor to the absence of a general mechanistic explanation of their bioactivity is the complexity of flavonoid chemistry in aqueous solutions at neutral pH. Flavonoids have acidic protons, are redox active, and frequently auto-oxidize to produce an array of degradation products including electrophilic quinones. Flavonoids are also known to interact with specificity and high affinity with a variety of proteins, and there is evidence that some of these interactions may be covalent. This review summarizes the mechanisms of flavonoid oxidation in aqueous solutions at neutral pH and proposes the formation of protein-flavonoid adducts or flavonoid-induced protein oxidation as putative mechanisms of flavonoid bioactivity in cells. Nucleophilic residues in proteins may be able to form covalent bonds with flavonoid quinones; alternatively, specific amino acid residues such as cysteine, methionine, or tyrosine in proteins could be oxidized by flavonoids. In either case, these protein-flavonoid interactions would likely occur at specific binding sites and the formation of these types of products could effectively explain how flavonoids modify proteins in cells to induce downstream biochemical and cellular changes.
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spelling doaj.art-b294d166c801486f8dbe16b2e31f37842023-11-22T08:56:48ZengMDPI AGMolecules1420-30492021-08-012616510210.3390/molecules26165102Protein Adducts and Protein Oxidation as Molecular Mechanisms of Flavonoid BioactivityP. Matthew Joyner0Natural Science Division, Pepperdine University, 24255 Pacific Coast Highway, Malibu, CA 90263, USAThere are tens of thousands of scientific papers about flavonoids and their impacts on human health. However, despite the vast amount of energy that has been put toward studying these compounds, a unified molecular mechanism that explains their bioactivity remains elusive. One contributing factor to the absence of a general mechanistic explanation of their bioactivity is the complexity of flavonoid chemistry in aqueous solutions at neutral pH. Flavonoids have acidic protons, are redox active, and frequently auto-oxidize to produce an array of degradation products including electrophilic quinones. Flavonoids are also known to interact with specificity and high affinity with a variety of proteins, and there is evidence that some of these interactions may be covalent. This review summarizes the mechanisms of flavonoid oxidation in aqueous solutions at neutral pH and proposes the formation of protein-flavonoid adducts or flavonoid-induced protein oxidation as putative mechanisms of flavonoid bioactivity in cells. Nucleophilic residues in proteins may be able to form covalent bonds with flavonoid quinones; alternatively, specific amino acid residues such as cysteine, methionine, or tyrosine in proteins could be oxidized by flavonoids. In either case, these protein-flavonoid interactions would likely occur at specific binding sites and the formation of these types of products could effectively explain how flavonoids modify proteins in cells to induce downstream biochemical and cellular changes.https://www.mdpi.com/1420-3049/26/16/5102flavonoidsprotein adductsquinonesquercetinEGCGflavonoid bioactivity
spellingShingle P. Matthew Joyner
Protein Adducts and Protein Oxidation as Molecular Mechanisms of Flavonoid Bioactivity
Molecules
flavonoids
protein adducts
quinones
quercetin
EGCG
flavonoid bioactivity
title Protein Adducts and Protein Oxidation as Molecular Mechanisms of Flavonoid Bioactivity
title_full Protein Adducts and Protein Oxidation as Molecular Mechanisms of Flavonoid Bioactivity
title_fullStr Protein Adducts and Protein Oxidation as Molecular Mechanisms of Flavonoid Bioactivity
title_full_unstemmed Protein Adducts and Protein Oxidation as Molecular Mechanisms of Flavonoid Bioactivity
title_short Protein Adducts and Protein Oxidation as Molecular Mechanisms of Flavonoid Bioactivity
title_sort protein adducts and protein oxidation as molecular mechanisms of flavonoid bioactivity
topic flavonoids
protein adducts
quinones
quercetin
EGCG
flavonoid bioactivity
url https://www.mdpi.com/1420-3049/26/16/5102
work_keys_str_mv AT pmatthewjoyner proteinadductsandproteinoxidationasmolecularmechanismsofflavonoidbioactivity