Chemical and physical characterization, stability and antioxidant activity of avicularin/(2-hydroxypropyl)-β-cyclodextrin inclusion complex

Abstract

Avicularin, commonly found in apples and mangos, possessed various health-promoting effects. However, the application of avicularin in functional foods was hindered by its limited water solubility and chemical instability. A freeze-drying-based technique was employed to formulate a complex using avicularin and (2-hydroxypropyl)-β-cyclodextrin (HP-β-CD) to improve these properties. The synthesis and structure of the complex were featured by changes in fourier transform infrared spectroscopy (FT-IR), the phase transition recorded by differential scanning calorimetry (DSC), the changes in crystal structures provided by X-ray diffractometry (XRD), the visualized changes in surface morphology determined by scanning electron microscopy (SEM). Additionally, proton nuclear magnetic resonance spectroscopy (¹H NMR) analysis and molecular docking simulations demonstrated the A ring of avicularin entered into the cavity of HP-β-CD to form a supramolecular complex. The complex of avicularin resulted in its increased water solubility (22 times), and enhanced chemical stability against heat and alkaline conditions, especially at pH 9,10, with an improvement of up to 50%. Meanwhile, the inclusion complex improved antioxidant activity in the cellular assays, especially at 120 μg/mL, with an improvement of up to 35%. This work provided a solid basis for potential applications of avicularin in functional foods and nutraceuticals.