Persimmon proanthocyanidins–mucins interaction mechanism: structural characteristics, rheological properties, and molecular docking

BACKGROUND: Mucins (MUCs), as the principal constituents of mucus, are closely associated with the transportation and absorption of various bioactive compounds. This study investigated the structural and rheological characteristics of persimmon proanthocyanidin (PPA)-MUC complexes and the interaction mechanism between PPAs and MUCs to elucidate the influence of MUCs on the digestion behavior of PPAs. RESULTS: Atomic force microscopy illustrated that the interaction between PPAs and MUC altered the aggregation state and particle size of MUC. Circular dichroism and X-ray diffraction analyses indicated that PPAs induced changes in the secondary and crystal structures of MUC. Rheological measurements demonstrated that both the storage (G') and loss (G″) moduli of PPA-MUC complexes increased with frequency, suggesting enhanced elastic fluid properties. Isothermal titration calorimetry indicated that the binding of PPAs and their structural monomers to MUC was exothermic (∆G < 0), with ∆H < 0 and ∆S < 0, indicating that the interaction was mainly driven by hydrogen bonding and van der Waals forces. An in silico molecular docking study further indicated that the 7-OH, 5'-OH, 3'-OH, and 3-O-gallate groups of PPA structural monomers could interact with the LYS, SER, and CYS amino acid residues of MUC2 through hydrogen bonding and van der Waals forces. CONCLUSION: Proanthocyanidins and MUC exhibited characteristic intermolecular interactions. These results provide new insights into the development of MUC-based nanocarrier systems to improve the intestinal bioavailability of PPAs. © 2026 Society of Chemical Industry.