Quantitative examination of oxidized polyphenol-protein complexes

Area of Science:

• Biochemistry
• Food Chemistry
• Oxidative Stress Research

Background:

• Polyphenols are plant compounds with potential health benefits.
• Protein oxidation can lead to loss of function and disease.
• Understanding polyphenol-protein interactions under oxidation is crucial for food and health sciences.

Purpose of the Study:

• To quantitatively investigate polyphenol-protein interactions under oxidative conditions.
• To model these interactions using radiolabeled 1,2,3,4,6-penta-O-galloyl-d-glucopyranose (PGG) and bovine serum albumin (BSA).

Main Methods:

• Utilized radiolabeled PGG and BSA as model compounds.
• Employed sodium periodate (NaIO(4)), ABTS radical cation (ABTS.+), and AAPH as model oxidants.
• Disrupted noncovalent interactions with sodium dodecyl sulfate.
• Isolated and quantified PGG-BSA products using trichloroacetic acid and radiochemical methods.

Main Results:

• NaIO(4) and ABTS.+ demonstrated faster oxidation of PGG-BSA complexes compared to AAPH.
• Sodium periodate rapidly formed soluble oxidized PGG-BSA complexes.
• Excess PGG over BSA led to the conversion of soluble complexes to insoluble forms.

Conclusions:

• The rate and outcome of polyphenol-protein interactions are oxidant-dependent.
• Stoichiometry plays a critical role in the solubility of oxidized polyphenol-protein complexes.