Structure-activity relationships and molecular mechanisms of six polyphenols in inhibiting hemoglobin-mediated lipid oxidation in unwashed surimi.

The inhibitory effects of polyphenols on hemoglobin (Hb)-mediated lipid oxidation are structure-dependent, but underlying regulatory mechanisms remain unclear. Six structurally distinct polyphenols were evaluated in unwashed surimi (UWS). Procyanidin B2 showed the best effect, reducing TBARS by 31.37%, scavenging 86.14% DPPH and 87.29% •OH, and decreasing metHb from 27.45% to 24.20%. Molecular dynamics and dynamic cross-correlation matrix (DCCM) analyses indicated that polyphenols bound to the heme-adjacent hydrophobic region, modulated local fluctuations, and increased the proportion of neutral correlated motions from 83.10% in free Hbβ to 88.58-92.89% in the polyphenol-bound systems. Neutral correlated motions were negatively correlated with metHb and TBARS and positively correlated with ABTS and •OH scavenging capacities and oxyHb. These findings suggest radical scavenging and modulation of Hb oxidation and heme-adjacent dynamics may jointly suppress lipid oxidation in UWS. Findings also suggest the potential of DCCM-derived dynamic features as descriptors for polyphenol screening, although further validation is required.