Preparation, characterization, solubilization and antioxidant activity of polyamine modified -cyclodextrins with baicalein inclusion complexes

Inclusion complexes of three different lengths of polyamine modified -cyclodextrins (-CDs) (hosts 1-3) with baicalein (BC) were prepared by a solution stirring method, and characterized by UV-Vis spectroscopy, proton nuclear magnetic resonance, scanning electron microscopy, thermogravimetric analysis, and X-ray diffractometry. The results demonstrated that 1:1 inclusion complexes of hosts 1-3 with BC are present. The binding ability of hosts 1-3 towards BC increased according to the sequence H1>H2>H3, which was in good agreement with the decreasing chain lengths of these hosts. When compared to BC, the inclusion complexes produced 508-, 451- and 323-fold enhancement in water solubility, respectively. At low concentrations, inclusion complexes 1/BC and 3/BC were observed with a better capacity of scavenging when compared to that of free BC. These findings reflected that the complexation strengthened the antioxidant activity of BC. Moreover, the solubility in water and resistance to oxidation of hosts 1-3/BC were satisfactory, making it possible candidates for application in herbal medicine and as healthcare products.