Gamma oryzanol loaded microspheres with improved bioavailability

Gamma oryzanol is a phytosterol that is extracted from rice bran oil. It is an antioxidant that possesses a curative effect for many diseases. Gamma oryzanol is a water insoluble compound supporting the idea that it has a low bioavailability due to low intestinal absorption. In this study, γ-oryzanol was loaded in biodegradable microspheres. Intestinal absorption of γ-oryzanol from microspheres was compared with that absorbed from triolein solution in rabbits. After oral administration of 150 mg/kg of body weight, plasma was collected at intervals and analyzed for γ-oryzanol content using high performance liquid chromatography (HPLC). Results showed that the highest plasma concentration of γ-oryzanol, detected from triolein solution, was 6.37 ± 1.48 µg/ml, whereas the highest plasma concentration from γ-oryzanol microspheres was 130.30 ± 30.40 µg/ml. This concentration was significantly higher than the amount absorbed from triolein solution (p<0.01). In conclusion, microspheres offer an alternative dosage form for γ-oryzanol solution with improved bioavailability. Key words: Gamma oryzanol, solution, microspheres, bioavailability.