Studies on the preparation and photostability of avobenzone and (2-hydroxy)propyl-β-cyclodextrin inclusion complex

Abstract The inclusion complex of avobenzone and (2-hydroxy)propyl-β-cyclodextrin (2-HP-β-CD) was prepared successfully. The effects of the inclusion behavior of avobenzone with 2-HP-β-CD were investigated in both solution and the solid state with the following methods: UV–vis spectrophotometry (UV–vis), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TG), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM), proton nuclear magnetic resonance ( 1 H-NMR) and two-dimensional rotational frame nuclear overhauser effect spectroscopy (2D ROESY). The photostability of avobenzone and its inclusion complex were both investigated by UV–vis spectrophotometry. The Benesi-Hildebrand’s method showed that avobenzone formed 1:2 stoichiometric inclusion complex with 2-HP-β-CD. The solubility, thermal stability and the photostability of avobenzone were all improved after encapsulating by the 2-HP-β-CD. Therefore, it can be a potentially promising way to promote its cosmetic preparations in UVA sunscreen.