Sulfobutyl ether cyclodextrin inclusion complexes containing tea polyphenols: Preparation, characterization, antioxidant activity, α-glucosidase inhibition, and in vitro release property

Tea polyphenols (TP) is popular due to strong biological activity, however, the instability of TP limits its application. In this study, inclusion complexes (TP-SBE) of TP with sulfobutyl ether β-cyclodextrin (SBE) were synthesized to improve the stability and bioactivity of TP. To retain more active components and obtain powder with good morphology, TP-SBE was prepared by freeze-drying and characterized by Ultraviolet-visible, Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, Thermogravimetric-differential scanning calorimetry and X-ray Diffraction Spectroscopy, which showed that the TP was successfully encapsulated by SBE and the thermal stability was improved. The effects of mass ratio, inclusion temperature, stirring speed, and inclusion time on the encapsulation rate of the synthesized TP-SBE were also determined, and the encapsulation rate reached 98.29% ± 1.65% under the optimal conditions. The in vitro activity assay showed that the IC 50 of TP-SBE on 2,2-Diphenyl-1-picrylhydrazyl and 2,2-Azinobis-(3-ethylbenzthiazoline-6-sulphonate) was 16.24±0.99 μg/mL and 5.13±0.17 μg/mL, and the scavenging effect on free radicals and α-glucosidase was more substantial than that of TP. The release of TP slowed down by SBE encapsulation and showed pH-selective. These data suggested that TP can be developed as a nutraceutical with antioxidant and hypoglycemic properties.