Phospholipids modulate interfacial localization of polyphenols in camellia oil: A molecular dynamics and experimental study on antioxidant interaction

While phospholipids are known to affect the antioxidant efficacy of polyphenols in oils, the molecular-scale mechanism underlying this interaction remains unclear. This study elucidated this mechanism through an integrated approach combining quantum chemical calculations, accelerated oxidation experiments, and molecular dynamics simulations. Among four tested polyphenols (camelliaside A, camelliaside B, kaempferol, and quercetin), quercetin demonstrated the highest antioxidant activity, with the lowest IC 50 values for scavenging DPPH (43.78 μmol/L) and ABTS radicals (178.40 μmol/L), and the highest inhibition (87.68%) against lipid hydroperoxides (LOOH). Quantitative interaction analysis using mixture effect (ME) values revealed that, among all polyphenol-phospholipid combinations, the quercetin-phosphatidylethanolamine (PE) pair uniquely a near-additive effect (ME = 0.97) without significant antagonism. Molecular dynamics simulations revealed that PE self-assembles into reverse micellar structures within the oil phase, which recruit and concentrate quercetin at the oil–water interface. This interfacial localization likely mitigates the antagonistic interactions observed in other combinations, preserving the additive antioxidant efficacy. The quercetin-PE combination achieved 94.85% LOOH inhibition, outperforming butylated hydroxytoluene (92.28%), demonstrating the practical potential of optimizing interfacial behavior rather than seeking synergism per se. The findings provide a mechanistic basis for designing effective, natural antioxidant systems to improve vegetable oil stability.