Ferulic acid (FA) provides broad biological functions that have been used in cosmetics formulation as a photoprotection, anti-aging, and brightening agent. However, its application is limited by its tendency to deteriorate by exposure to heat, humidity, and light. This study aimed to enhance the stability of FA by encapsulation in phosphorylated rice starch (PRS) and evaluate its effect on improving human skin. First, FA was encapsulated in PRS and characterized by FTIR, SEM, XRD, and DSC. Then, its stability when exposed to a temperature of 45 °C and light and its anti-aging effect on 16 volunteers were investigated. The results indicated that FA was successfully encapsulated in PRS with an encapsulation yield of 77%, EE (73%) and LE (65%). After 1 month at the high temperature/80%RH, the encapsulated FA retained its quantity (70%), whereas free FA was retained at only 50%. Under light exposure conditions, the encapsulated FA was retained at 65%, which was higher than FA (35%). Franz diffusion cell was used and demonstrated that PRS provided the controlled release of FA. Application of encapsulated FA and FA creams showed an absence of skin irritation in all volunteers. After 1 month, the encapsulated FA cream was found to be better than the FA cream on skin lightening, elasticity, smoothness, roughness, scaliness, and wrinkle. The results indicated that PRS is a potential wall material for enhancing the stability of FA, resulting in more efficacious skin lightening and anti-aging properties.
Keywords: anti-aging; clinical evaluation; ferulic acid; phosphorylated starches; skin lightening.