Anti-diabetic activity of oryzanol and its relationship with the anti-oxidant property

Experimental evidence suggests that oxidative stress induced by streptozotocin (STZ) damage the pancreatic beta cells and produce hyperglycemia in rats. The current study was initiated to investigate the effects of oryzanol (OZ), a commercially-important bioactive phytochemical isolated from crude rice bran oil (cRBO) against experimental diabetes as well as the antioxidant potential of the drug. OZ was isolated by a two-step solvent crystallization process from cRBO, which was extracted from fresh rice bran by hexane mediated soxhlet extraction. Oral administration of OZ (50 and 100 mg/kg) reduced the blood glucose level in normal and in STZ (45 mg/kg, intravenous) diabetic rats in both single and multidose study. Oxidative stress produced by STZ was found to be significantly reduced by OZ when compared to control rats, as evident from a significant decrease in the extent of lipid peroxidation (LPO) and increased levels of enzymatic anti-oxidants such as superoxide dismutase (SOD) and reduced glutathione (GSH) in the liver. The findings indicate that OZ possesses the potential to effectively ameliorate the oxidative stress induced by STZ and produce a reduction in blood glucose levels. However, further experiments at the clinical level are warranted to confirm the utility of OZ in the therapeutic management of diabetes mellitus.