Purification and identification of rice bran (Oryza sativa L.) phenolic compounds with in-vitro antioxidant and antidiabetic activity using macroporous resins

This study was designed to establish an efficient purification method for phenolic compounds from rice bran and to acquire insightful knowledge of purification impact on its chemical constituents, antioxidant and antidiabetic activity. Among the eight macroporous resins investigated, HPD-300 resin was verified to bosses superior adsorption and desorption qualities for the extract. Purification parameters were optimised. Eighteen phenolic compounds were identified using HPLC-PDA, the contents of ferulic acid and syringaldehyde were significantly (P < 0.05) higher than the other constituents. However, phenolic compounds concentrations varied significantly (P < 0.05) after HPD-300 resin purification. In addition, the extract exhibited a significant (P < 0.05) increase in total flavonoid contents, in vitro antioxidant (DPPH and FRAP) and antidiabetic (α-glucosidase and BSA-glycation inhibition) activity after HPD-300 resin treatment. These findings indicate that selection of resin and applying optimal purification condition is an appropriate economical approach for obtaining bioactive phenolic compounds from rice bran.