Physicochemical Characterization of Inclusion Complex of Catechin and Glucosyl-β-Cyclodextrin

Purpose: To investigate the suitability of glucosyl-β-cyclodextrin (G-β-CD) to form inclusion complex with catechin, and characterize the physicochemical properties of the inclusion complex of catechin and G-β-CD. Methods: Catechin and G-β-CD was mixed in water at the same molar ratio, stirred at 20 °C for 48 h and lyophilized to obtain the complex. Its physicochemical properties were investigated by ultravioletvisible spectrometry (UV), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffractometry (XRD) and differential scanning calorimetry (DSC). Results: The characteristic UV absorption peaks for catechin, the physical mixture and the complex occurred at 279 nm. There was no significant difference between the IR spectra of the physical mixture and the complex. SEM and XRD data indicate that catechin was molecularly distributed in G-β-CD matrix and lost its crystallinity in the process. DSC indicate that the heat stability of catechin was significantly improved by complexing with G-β-CD. Conclusion: Catechin can efficiently interact with G-β-CD to form a complex by freeze-drying method. The complex of catechin and G-β-CD resulted in the changes in some of the characteristic spectral and thermal properties of the former. Furthermore, the heat stability of catechin is significantly improved.