Physicochemical interactions of cycloamylose with phenolic compounds

The complex formation capability of cycloamylose (CA), having a degree of polymerization of 23-45, with phenolic compounds (PCs) was investigated using various physicochemical techniques. The fluorescence intensity of PCs increased and then reached a plateau at 10-20mM cyclodextrin, while it continued to increase at up to 60mM CA. Thermodynamic data of CA complexes with PCs revealed that the binding process was primarily enthalpy-driven and spontaneous. CA favored to form the most stable complex with chlorogenic acid (CHA) among all PCs. Chemical shift changes for the protons in interior and exterior of CA, as well as in PCs suggested a possible formation of both inclusion and extramolecular interactions between CA and PCs. The ROESY spectrum confirmed that the aromatic moieties of CHA were partially interacted with CA molecules through relatively weak binding. XRD, DSC, and SEM results also supported the complex formation by intermolecular interaction between CA and CHA.