TY - JOUR
T1 - Polyphenol autoxidation and prooxidative activity induce protein oxidation and protein-polyphenol adduct formation in model systems
AU - Bayati, Mohammad
A2 - Poojary, Mahesha Manjunatha
PY - 2025
Y1 - 2025
N2 - Polyphenols are well-known for their antioxidant properties, but their prooxidative activity remain less understood. This study quantitatively examined the formation of hydrogen peroxide (H2O2) during the autooxidation of nine different polyphenols in model systems, investigating how it impacts protein oxidation and protein-polyphenol covalent adduct formation. Polyphenols (4 mM) generated H2O2 in the range of 0.2–242 μM, depending on type of polyphenol, incubation time, temperature, and pH, but no clear relationship between polyphenol structure and H2O2 production was observed. The presence of free amino acids and proteins (bovine serum albumin and β-lactoglobulin) inhibited H2O2 formation, with Cys completely scavenging H2O2. Met was highly susceptible to oxidation with a 25–75% loss, forming methionine sulfoxide through a two-electron oxidation pathway. Trp and Tyr were oxidized to produce dioxindolyl-L-alanine, kynurenine, 3,4-dihydroxyphenylalanine, N′-formylkynurenine, and 5-hydroxytryptophan in the nmol/mol-mmol/mol amino acid range. Furthermore, autoxidation of polyphenols resulted in >177 distinct amino acid/protein-polyphenol adducts as identified using LC-Orbitrap-MS/MS analysis.
AB - Polyphenols are well-known for their antioxidant properties, but their prooxidative activity remain less understood. This study quantitatively examined the formation of hydrogen peroxide (H2O2) during the autooxidation of nine different polyphenols in model systems, investigating how it impacts protein oxidation and protein-polyphenol covalent adduct formation. Polyphenols (4 mM) generated H2O2 in the range of 0.2–242 μM, depending on type of polyphenol, incubation time, temperature, and pH, but no clear relationship between polyphenol structure and H2O2 production was observed. The presence of free amino acids and proteins (bovine serum albumin and β-lactoglobulin) inhibited H2O2 formation, with Cys completely scavenging H2O2. Met was highly susceptible to oxidation with a 25–75% loss, forming methionine sulfoxide through a two-electron oxidation pathway. Trp and Tyr were oxidized to produce dioxindolyl-L-alanine, kynurenine, 3,4-dihydroxyphenylalanine, N′-formylkynurenine, and 5-hydroxytryptophan in the nmol/mol-mmol/mol amino acid range. Furthermore, autoxidation of polyphenols resulted in >177 distinct amino acid/protein-polyphenol adducts as identified using LC-Orbitrap-MS/MS analysis.
U2 - 10.1016/j.foodchem.2024.142208
DO - 10.1016/j.foodchem.2024.142208
M3 - Journal article
VL - 466
JO - Food Chemistry
JF - Food Chemistry
SN - 0308-8146
M1 - 142208
ER -