Non-aqueous nanoemulsions as a new strategy for topical application of astaxanthin

The application of astaxanthin is limited by its poor solubility and stability. In the present study, astaxanthin non-aqueous nanoemulsions (ASX-NANE) were developed by high-pressure homogenization method to combine advantages of nanocarriers and non-aqueous emulsions. ASX-NANE had a spherical morphology with a uniformed size distribution and a high entrapment efficiency (98.4 ± 0.3%). The analysis of FTIR indicated that astaxanthin was successfully encapsulated into the lipid core of ASX-NANE. This system was a stable emulsion system over a period of 4 weeks at 25 °C and could protect astaxanthin against degradation. In vitro cell study showed that ASX-NANE had a low toxicity and could protect cells against oxidative stress. In vitro permeation study and skin histological sections revealed the enhanced permeation of astaxanthin and the transformation of stratum corneum with a low systemic absorption and unchanged epidermis. Therefore, non-aqueous nanoemulsions might be an appropriate strategy for the topical application of astaxanthin.