Preparation, in-vitro release and antioxidant potential of formulation of apigenin with hydroxypropyl-β-cyclodextrin modified microemulsion

This work was carried out to exploit the feasibility of microemulsion combining apigenin/hydroxypropyl-β-cyclodextrin (API/HP-β-CD) complex as the carrier for improving the solubility of API, a bioactive flavonoid with various pharmacological activities. The API/HP-β-CD complex in solid state was prepared by solvent-freeze-drying method and characterized by FT-IR, PXRD and 1H NMR. To further increase the solubility of API, the complex of HP-β-CD with food-grade cosurfactant-free microemulsion was constructed. The aqueous solubility of API significantly increases in the HP-β-CD/Microemulsion complex, via solubilizing dominantly into the “palisade” layer, minor outer phase and inner core. The HP-β-CD modified microemulsion improves the cumulative percentage of API released. Moreover, API loaded in microemulsions with HP-β-CD had a higher antioxidant activity than that without HP-β-CD.