Binding interaction between rice bran albumin and sweet potato leaves polyphenol: Multi-spectroscopic and simulated molecular docking analysis

In this study, the changes in functional properties and binding mechanisms at the molecular level of a non-covalent complex formed between sweet potato leaf polyphenols (SPLPs) and rice bran albumin (RBA) were investigated. Multi-spectral analysis indicated that SPLPs statically quenched the intrinsic fluorescence of RBA, and fitting to a double logarithmic equation revealed that hydrogen bonding constituted the primary driving force behind this interaction. Consequently, the conformational structure, microenvironment, and surface hydrophobicity of RBA were significantly impacted. With 7 μmol/L of SPLPs added to RBA, the emulsifying activity and stability of the complexes were enhanced by 45.71 % and 392.30 %, respectively, compared to RBA. Similarly, the thermal stability of 3,5-diCQA was enhanced by 176.29 %, alongside an improved ultraviolet tolerance. Molecular docking and molecular dynamics simulations clarified that the A0A191ANP5, B8AHL6 and P52428 subunit in RBA has a stronger affinity with the most abundant polyphenols in SPLPs, which was the 3,5-disubstituted caffeoylquinic acid (3,5-diCQA). These findings may furnish a theoretical foundation for the prospective utilization of SPLPs and RBA complex products as functional food ingredients.