The interaction mechanism of oligopeptides containing aromatic rings with β-cyclodextrin and its derivatives.

We investigate the formation mechanism of supramolecular complexes of four antioxidant oligopeptides (YW, WY, WYS, and WYSL) with β-cyclodextrin (β-CD), hydroxypropyl-β-cyclodextrin (HP-β-CD) and 6-O-α-maltosyl-β-cyclodextrin (M-β-CD) by combined computational and experimental methods. The formation of complexes is determined by UV, IR and DSC, and the rank-ordered acquired stability of the complexes is as follows: WYSL/HP-β-CD > WYS/HP-β-CD > WY/HP-β-CD > YW/M-β-CD > YW/HP-β-CD > YW/β-CD. The 1H NMR analysis and molecular docking results reveal that the aromatic rings of these oligopeptides are embedded into the cavities of the studied β-CD and its derivatives, indicating that hydrophobic interaction is a major driving force for the formation of the complexes. We also demonstrate that H-bonds play a key role in maintaining the supramolecular complexes. In addition, the results of the antioxidant assay indicate that the radical scavenging capacity of the oligopeptides is enhanced by the CD-based inclusion.