Assessment of Skin Permeability of Components Derived from Rice Bran

Abstract

Rice bran is a by-product obtained during the polishing process of white rice and constitutes about 10% of the weight of unpolished rice. Extracts from rice bran contains various functional components, including inositol, ferulic acid, and γ-oryzanol. In recent years, the beneficial effects of these components derived from rice bran on the skin have been reported and attempts to use them as cosmetic raw materials are spreading. For these components to be effective, it is crucial that they penetrate the stratum corneum and reach their target sites within the skin. To explore this, we conducted in vitro skin permeation studies using human skin tissue sections with the stratum corneum, and diffusion cell equipment. Cosmetic formulations containing 1% concentrations of inositol, ferulic acid, or γ-oryzanol were prepared and applied to human skin tissue sections placed in a diffusion cell. The receptor fluid was collected at intervals of 2, 4, and 6 h and analyzed to determine the concentration of these substances. The results showed that ferulic acid exhibited the highest skin permeability, with an average of 352.67±234.45 μg/cm² over 6 h. This was followed by inositol, with an average permeability of 162.15±66.89 μg/cm² over the same period, and γ-oryzanol, with 46.10±12.60 μg/cm². These components derived from rice bran can penetrate the stratum corneum and potentially provide beneficial effects to skin cells.