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

Abstract

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.

Characterization of the Antioxidant Effects of γ‐Oryzanol: Involvement of the Nrf2 Pathway

“…Different studies suggested that ORY could exert its antioxidant effects by modulating the endogenous antioxidant enzyme activities. In particular, SOD has been found to be positively regulated by ORY [ 26 , 33 , 34 ]. Here, we evaluated the protein expression and activity of SOD enzymes in the presence of ORY 24h alone or followed by oxidative insult.…”

Redox Homeostasis and Natural Dietary Compounds: Focusing on Antioxidants of Rice (Oryza sativa L.)

“…In Drosophila melanogaster model, γ-oryzanol enhanced antioxidant defense by significantly improving the antioxidant enzymes such as SOD, CAT, and GST, and decreasing the malondialdehyde (MDA) and ROS production [ 205 ]. In streptozotocin-induced oxidative stress, γ-oryzanol also effectively increased the levels of SOD and reduced glutathione in rats [ 206 ]. In mice model of ethanol-induced liver injury, γ-oryzanol was able to prevent increased hepatic lipid hydroperoxide, TBARS levels as well as plasma aspartate and alanine aminotransferase activities.…”

Investigation of nutriactive phytochemical – gamma‐oryzanol in experimental animal models

“…Furthermore, GO‐treated mice better recovered from an ethanol‐induced decrease in the hepatic glutathione level together with enhancing superoxide dismutase activity. GO effectiveness in ameliorating streptozotocin‐induced oxidative stress in rats (Ghatak and Panchal, ) is detailed in the chapter concerning diabetes management.…”