CHITOSAN AND MODIFIED CYCLODEXTRIN NANOPARTICLES FOR DELIVERY OF ANTIOXIDANTS IN HUMAN KERATINOCYTES

Aims: This study investigated the protective effects of hydrophilic Glutathione (GSH) and lipophilic Idebenone (IDE) delivered by chitosan and cyclodextrin nanoparticles (NPs) in human keratinocytes. Methodology: The NPs were prepared using the ionic gelation technique, which allows GSH to covalently bond to Chitosan (CS) and then to physically complex CS-GSH with IDE and Sulfobutylether-β-cyclodextrin. Physico-chemical characterization of these NPs included size and zeta potential. The release of IDE from NPs was assessed using a Franz diffusion cell, and the antioxidant activity by the DPPH radical test. The NP in vitro cytotoxicity was tested on HaCaT and NCTC 2544 cell lines and flow cytometry techniques were used for measuring intracellular reactive oxygen species (ROS), and mitochondrial efficiency. The content of intracellular thiols was evaluated by DTNB on NCTC 2544 cells under pro-oxidizing conditions. Results: The NPs obtained showed small (376nm) particle size, a positive zeta potential and a pH close to 5 to ensure good skin tolerability. Only IDE was released from NPs assessed using the Franz diffusion cell and IDE loaded into NP showed a strong antioxidant activity compared to the free form. No cytotoxicity was observed at 24h or 48h on HaCaT and NCTC 2544 keratinocytes in the 0-2.3M and 0-5µM concentration range respectively. Pre-treatment of both cell lines with NPs loaded with IDE (0-2.5 µM) showed no reduction of the intracellular thiol content and protected keratinocytes from oxidative stress induced by hydrogen peroxide. Modest protection of mitochondrial efficiency was also observed. Conclusion: The results of this study show that IDE can be loaded onto a hydrophilic delivery system, avoiding the use of organic solvents commonly employed for its solubilization, whilst maintaining a significant antioxidant activity. Therefore, these NPs represent a promising strategy for the formulations of topical treatments containing antioxidants.