Photochemical and antioxidant properties of gamma-oryzanol in beta-cyclodextrin-based nanosponges

Gamma-oryzanol (GO), a mixture of ferulic acid esters, has recently attracted a great interest as natural antioxidant extracted from rice-bran oil, usually employed to stabilize food and pharmaceutical raw materials, moreover as sunscreen in cosmetic formulations. Its usefulness, however, is limited by its fast degradation. A recently proposed approach to increase the stability and effectiveness of antioxidants is based on the inclusion in supramolecular structures (nanoparticles, cyclodextrins, liposomes, etc.). In this work we studied the inclusion of GO in β-cyclodextrin-based nanosponges which in the last few years have been chosen for their ability to encapsulate a great variety of substances to decrease their side-effects and to protect them from degradation. The inclusion complex was prepared in 1:1 w/w ratio and characterized by DSC, XRPD and membrane diffusion runs. The photodegradation of GO upon either UVA or UVB irradiation was found to be slowed down by inclusion in nanosponges. The antioxidant effectiveness of the inclusion complex was also assessed and in vitro experiments on porcine ear skin revealed a certain accumulation of GO also when entrapped in the host structure.