Impact of nanosizing on dermal delivery and antioxidant activity of quercetin nanocrystals

Quercetin is one of the most effective natural compounds against skin disorders related to inflammatory and oxidative processes. However, its efficacy is generally limited by its low bioavailability mainly due to the poor water solubility. In this work, quercetin was formulated as nanosuspension in order to investigate whether the nanosizing approach could improve both its saturation solubility and cutaneous bioavailability. Quercetin nanosuspensions at two different concentrations (3 and 5%), were obtained by a wet media milling technique using Tween 80 and Poloxamer 188 as stabilizers. The obtained nanocrystals were deeply characterized by using different techniques such as Scanning Electron Microscopy, Differential Scanning Calorimetry, X-Ray Powder Diffractometry, Fourier Transform Infrared Spectroscopy and Photon Correlation Spectroscopy. Quercetin nanocrystals exhibited a mean diameter ranging between 326 and 474 nm and a polydispersity index lower than 0.30. Moreover, the size reduction greatly improves quercetin solubility and dissolution rate, thus promoting its accumulation in the different skin layers. Finally, in vitro studies using keratinocytes showed the high biocompatibility of nanosuspensions and their ability to counteract the oxidative effect of hydrogen peroxide on cells, suggesting their possible use for the treatment of skin disorders.