Photoprotective Activity of Citrus sinensis Peel Crude Extract: In vitro Analytical Method and Formulation

Background: Peel extract of Citrus sinensis is rich in beneficial phytochemicals that can protect the skin from the harmful effects of UV radiation. This study evaluates the suitability of C. sinensis peel waste as the primary active ingredient in a photoprotective formulation. Materials and Methods: Freeze-dried powder of C. sinensis peel was extracted using Soxhlet extract, with ethyl acetate as the solvent, and formulated into sunscreen formulation. Results: Phytochemical evaluation of the crude extract revealed that the flavonoid, phenolic and terpenoid contents were 35.21±2.3 mg quercetin equivalent (QE)/g, 59.40±3.0 mg gallic acid equivalent (GAE)/g and 3.33±0.1 mg linalool/g, respectively. The photoprotective properties and free radical scavenging activity of the formulation were investigated by Sun Protection Factor (SPF) and 2,2’-Diphenyl-1- picrylhydrazyl (DPPH) assay. The sunscreen formulation exhibited photoprotective activity with SPF value of 2.41±0.01 and a strong scavenging activity with IC50 value of 37.3±2.26 ppm. The physical evaluations of the formulation (organoleptic evaluation, pH, viscosity, spreadability and the type of emulsion) were performed and showed a stable profile for 5 weeks of storage. Conclusion: The findings indicate that the sunscreen formulation containing ethyl acetate peel extract of C. sinensis may provide indirect photoprotection by reducing UV-induced oxidative stress, a critical contributor to skin inflammation and photoaging. Moreover, improved and valuable antioxidant effect is expected when applying of the developed formulation topically.