Interaction and Antioxidant Functions of Lactoferrin-Polygonatum sibiricum Polysaccharide Complexes at Different pH

The interactions between proteins and polysaccharides are of great significance in the development of innovative functional foods. This study aimed to systematically explore the interaction mechanisms between lactoferrin (LF) and Polygonatum sibiricum polysaccharide (PSP) and evaluate their antioxidant activities. The interactions between LF and PSP within the pH range of 3.0-8.0 were characterized by multispectroscopic techniques such as fluorescence spectroscopy and infrared spectroscopy. It was found that the main driving force of their interaction was electrostatic adsorption. The binding of PSP induced changes in the secondary and tertiary structures of LF, thereby enhancing the antioxidant activity of LF. After adding PSP, the DPPH scavenging rate reached up to 81.79%, and the ABTS scavenging rate reached 93.18%. These findings provide new insights at the molecular level into protein-polysaccharide interactions and demonstrate the potential of LF-PSP complexes as natural antioxidants, which may facilitate the design of innovative functional dairy products.