Novel Pullulan/Gellan Gum Bilayer Film as a Vehicle for Silibinin-Loaded Nanocapsules in the Topical Treatment of Atopic Dermatitis

In this study a novel gellan gum/pullulan bilayer film containing silibinin-loaded nanocapsules was developed for topical treatment of atopic dermatitis (AD). The bilayer films were produced by applying a pullulan layer on a gellan gum layer incorporated with silibinin nanocapsules by two-step solvent casting method. The bilayer formation was confirmed by microscopic analysis. In vitro studies showed that pullulan imparts bioadhesitvity for the films and the presence of nanocapsules increased their occlusion factor almost 2-fold. Besides, the nano-based film presented a slow silibinin release and high affinity for cutaneous tissue. Moreover, this film presented high scavenger capacity and non-hemolytic property. In the in vivo study, interestingly, the treatments with vehicle film attenuated the scratching behavior and the ear edema in mice induced by 2,4-dinitrochlorobenzene (DNCB). However, the nano-based film containing silibinin modulated the inflammatory and oxidative parameters in a similar or more pronounced way than silibinin solution and vehicle film, as well as than hydrocortisone, a classical treatment of AD. In conclusion, these data suggest that itself gellan gum/pullulan bilayer film might attenuate the effects induced by DNCB, acting together with silibinin-loaded nanocapsules, which protected the skin from oxidative damage, improving the therapeutic effect in this AD-model.