Development and assessment of phospholipid-based luteolin-loaded lipid nanocapsules for skin delivery

Luteolin is an excellent flavone possessing several beneficial properties such as antioxidant and anti-inflammatory effects which are interesting for skin delivery. Development of an appropriate skin delivery system could be a promising strategy to improve luteolin cutaneous performance.So, the main aim of this work was to fabricate, characterize and evaluate phospholipid-based luteolin-loaded lipid nanocapsules for skin delivery. The influence of phospholipid/oil ratio, surfactant type and chitosan coating were investigated. The prepared formulations underwent in vitro assessment and the selected formulations were evaluated ex vivo and in vivo. The mean diameters of investigated formulations varied between 174 nm and 628 nm while zeta potential varied between -25.7 ± 4.8 mV and 6.8 ± 1.7 mV. Increasing in phospholipid/oil ratios resulted in decrease in particles size with little effect on zeta potential and drug encapsulation. Cremophor EL showed the lowest particle sizes and the highest drug encapsulation. Chitosan coating shifted zeta potential towards positive values. Structural analyses showed that luteolin is incorporated into lipid core of nanocapsules. Selected formulations (LNC4 and LNC13) exhibited sustained in vitro release and antioxidant activity. LNC13 (chitosan coated) showed higher flux (0.457 ± 0.113 µg/cm²/h), permeability (45.70 ± 11.66 *10^-5 cm²/h) and skin retention (121.66 ± 7.6 µg/cm² after 24 h) when compared to LNC4 and suspension. It also showed disordered the integrity of the stratum corneum, increased epidermal thickness and relieving most of inflammatory features in animal model. In conclusion, this study proves that lipid nanocapsules could effectively deliver luteolin into skin and then can be established as a potential system in the pharmaceutical and cosmeceutical horizons.