Development of γ-Oryzanol Rich Extract from Leum Pua Glutinous Rice Bran Loaded Nanostructured Lipid Carriers for Topical Delivery

Leum Pua is native Thai glutinous rice that contains antioxidants higher than white rice and other colored rice. One of the major antioxidants in rice brans is gamma-oryzanol (GO). In this study, Leum Pua glutinous rice bran was extracted by different solvents. Oleic acid (similar to 40 g/100 g extract), linoleic acid (similar to 30 g/100 g extract), and palmitic acid (similar to 20 g/100 g extract) were found to be major lipid components in the extracts. Methanol extract showed less variety of lipid components compared to the others. However, hexane extract showed the highest percent of gamma-oryzanol compared to other solvents. Therefore, the hexane extract was selected to prepare nanostructured lipid carriers (NLC). The prepared NLC had small particles in the size range of 142.9 +/- 0.4 nm for extract-loaded NLC and 137.1 +/- 0.5 nm for GO-loaded NLC with narrow size distribution (PI < 0.1) in both formulations. The release profile of extract-loaded NLC formulation was slightly higher than GO-loaded NLC formulation. However, they did not follow the Higuchi model because of small amounts of gamma-oryzanol loaded in NLC particles.