Abstract:This study aimed to elucidate the formation mechanism of lactoferrin–galangin (LF–GAL) complexes and evaluate their in vitro antioxidant activity. Noncovalent LF–GAL complexes were prepared using LF and GAL. Their particle size, surface charge, and morphology were characterized by dynamic light scattering and scanning electron microscopy. The binding behavior and principal interaction forces between LF and GAL were investigated using fluorescence spectroscopy. Antioxidant activity was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS+) radical-scavenging assays. The LF–GAL complexes exhibited an average hydrodynamic diameter of 170 ± 2.59 nm, a spherical morphology, and a positive surface charge under neutral conditions. Fluorescence spectroscopy showed that GAL effectively quenched the intrinsic fluorescence of LF and spontaneously associated with LF, predominantly through hydrogen bonding and van der Waals interactions. Compared with free GAL, the LF–GAL complexes exhibited significantly greater DPPH and ABTS+ radical-scavenging activities, indicating that complex formation enhanced the in vitro antioxidant capacity of GAL. These findings demonstrate that LF can form stable noncovalent complexes with GAL, potentially improving its aqueous dispersibility and antioxidant activity. Therefore, LF–GAL complexes may serve as promising delivery systems for natural antioxidants and functional ingredients in dairy-based foods.