Chitosan-based nanoparticles for rosmarinic acid ocular delivery—In vitro tests

In this study, chitosan nanoparticles were used to encapsulate antioxidant rosmarinic acid, Salvia officinalis (sage) and Satureja montana (savory) extracts as rosmarinic acid natural vehicles. The nanoparticles were prepared by ionic gelation using chitosan and sodium tripolyphosphate (TPP) in a mass ratio of 7:1, at pH 5.8. Particle size distribution analysis and transmission electron microscopy (TEM) confirmed the size ranging from 200 to 300 nm, while surface charge of nanoparticles ranged from 20 to 30 mV. Nanoparticles demonstrate to be safe without relevant cytotoxicity against retina pigment epithelium (ARPE-19) and human cornea cell line (HCE-T). The permeability study in HCE monolayer cell line showed an apparent permeability coefficient Papp of 3.41 ± 0.99 × 10−5 and 3.24 ± 0.79 × 10−5 cm/s for rosmarinic acid loaded chitosan nanoparticles and free in solution, respectively. In ARPE-19 monolayer cell line the Papp was 3.39 ± 0.18 × 10−5 and 3.60 ± 0.05 × 10−5 cm/s for rosmarinic acid loaded chitosan nanoparticles and free in solution, respectively. Considering the mucin interaction method, nanoparticles indicate mucoadhesive proprieties suggesting an increased retention time over the ocular mucosa after instillation. These nanoparticles may be promising drug delivery systems for ocular application in oxidative eye conditions.