Chitosan-Coated Nanostructured Lipid Carriers (NLCs) Incorporating Esters of Ferulic Acid with Photoprotective Activity

UV radiation is responsible for acute and chronic adverse effects on the skin. In recent years, it has been shown that various phenolic acids, particularly cinnamic acid derivatives, prevent some of these effects. In the present study, the design and synthesis of three esters of ferulic acid, analogues of the octyl methoxycinnamate (OMC), one of the most commercially used filters, are presented. The esters were evaluated for their photoprotective activity against UVA and UVB radiation. The ester 3b exhibited an SPF of 9.22 and a λc value of 343.9, higher than the values of OMC (SPF value: 8.19, λc value: 337.7). The development and optimization of a novel encapsulation process of the synthesized esters in nanostructured lipid carriers (NLCs) and coating of the NLCs with chitosan was also performed. The optimization of the coating processes was performed using a Box–Behnken experimental design. The optimal nanosystems exhibited a size of 117.0 ± 5 nm, enhanced stability in dispersion, and 78% encapsulation efficiency. The nanoparticles were characterized by ATR/FT–IR, TGA, and TEM. Incorporation of the nanoparticle dispersions in a sunscreen formulation increased the SPF factor of the formulation up to 48%. The esters and nanosystems also showed a satisfactory ability to inhibit the peroxidation of linoleic acid (AAPH induced lipid peroxidation assay) (74–91% inhibition).