Physiochemical Properties of the Inclusion Complex of Puerarin and Glucosyl-β-Cyclodextrin

Puerarin is a natural isoflavone, found in the Chinese medicinal plant Ge-gen, with many reported health-promoting properties. However, its low water solubility impedes its application in pharmaceutical and functional food products. This study explores the formation of inclusion complex between puerarin and glucosyl-β-cyclodextrin (G-β-CD) to improve the aqueous solubility of puerarin. The complex was prepared by mixing an equal molar mixture of puerarin and G-β-CD for 24 h, followed by freeze-drying. The obtained complex was analyzed by ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, X-ray diffractometry, and proton nuclear magnetic resonance spectroscopy. Results showed clearly that the process led to the formation of a supramolecular complex in which the guest molecule, puerarin, was entrapped inside the cavity of the host, G-β-CD. The close association between puerarin and G-β-CD resulted in changes in some of the characteristic spectral, phase-transitional, and morphological properties of puerarin.