Formulation and optimization of phytosomes of ethanolic extract of Viola tricolor flowers using design of experiment (DOE) to evaluate in vitro photoprotective potential as sunscreen cream

Abstract

Viola tricolor L. has many uses in treatment of various skin disorders, which attributed to their antioxidant-flavonoid compounds. The aim of this study was evaluation of photoprotection, cytotoxicity and phototoxicity of the ethanolic extract of Viola tricolor flowers (EE-Viola). At concentration of 0.2 mg/mL of EE-Viola, the sun protection factor (SPF) value was 15.3 ± 0.7. By evaluation of the survival of mouse fibroblast cells (3T3) in the presence and absence of UV light using MTT-based colorimetric assay, the calculated IC50 was found to be 30.79 µg/mL and 34.89 µg/mL, respectively. The phytosomes of EE-Viola (Phy&EE-Viola) were then prepared using thin-layer hydration technique and optimized by experimental design method. The optimum particle size (487.6 nm) and encapsulation efficiency (95.2%) of the prepared phytosomes obtained when ratio of extract amount to lecithin amount (3 to 1), experiment temperature of 50 °C, and bath sonication were used. The optimum prepared phytosome was characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, and differential scanning calorimetry. In the next step, Phy&EE-Viola was formulated in a cream base and its photoprotective potential was evaluated. Finally, the Phy&EE-Viola cream was evaluated for its pH, spread-ability, occlusivity, in vitro SPF determination, release and stability studies. The SPF value of the cream containing 4% of Phy&EE-Viola was equal to 14.0 ± 0.7. The results clearly indicated that the cream formulations exhibited a good stability at applied temperatures and good release profile. Therefore, the obtained cream of Phy&EE-Viola might be introduced as candidate as for sun protection which merit further investigations.