RESUMO
Objective: To elucidate the protective effects of rice bran water extract on the expression of endothelial nitric oxide synthase (eNOS), nuclear factor-kappa B (NF-kB), and a cluster of differentiation 36 (CD36) in the vasculature of high-fat diet-fed rats. Methods: Male Sprague-Dawley rats were divided into three groups. Group I served as control, Group II was treated with high-fat diet, and Group III was treated with high-fat diet and rice bran water extract at 2 205 mg/kg/day. After four weeks, the metabolic parameters, malondialdehyde as a marker of oxidative stress, and histological features of the aorta were evaluated. The levels of transcripts and proteins in aorta were determined by real-time PCR and Western blot analysis, respectively. Results: In comparison with the Group II, rice bran water extract administration resulted in a significant reduction in body weight, visceral fat tissue weights, blood glucose levels, and serum total-cholesterol and free fatty acid levels in Group III. Serum triglyceride levels tended to decrease in the Group III. Also, rice bran water extract administration obviously decreased malondialdehyde levels in both serum and aorta. Interestingly, rice bran water extract treatment demonstrated a significant up-regulation of eNOS expression and down-regulation of NF-kB p65 and CD36 expressions. Nonetheless, all groups showed normal histology of aorta. Conclusions: Rice bran water extract exhibited vasoprotective effects in the high-fat diet-induced obesity condition by modulating the expression of eNOS, NF-kB, and CD36 and metabolic parameters.
RESUMO
BACKGROUND: Free radical-induced oxidative stress damages cellular components leading to many human diseases. Plant-derived antioxidant compounds have become a profitable alternative to prevent oxidative stress in cells. OBJECTIVE: To determine and compare total phenolic and flavonoid contents as well as antioxidant activity using both chemical and cell assays in the water extracts of brown rice and rice bran from two Thai rice cultivars: Sangyod, a red pigmented rice typically grown in Southern Thailand and Dawk Mali 105, a commercial white-colored rice. MATERIAL AND METHOD: All the rice water extracts were analyzed for their total phenolic and flavonoid contents using the colorimetric assays, as well as for their antioxidant activity through two chemical assays: DPPH radical-scavenging and inhibition of lipid peroxidation assays, as well as through cell-based assays: scavenging capacity of intracellular ROS in HL60 cells using the fluorescent DCF and the NBT reduction. RESULTS: The two chemical assays detected free radical scavenging and free radical chain breaking activities in all the rice extracts with EC50 values ranging from 26 to 357 microg/ml. Moreover, the cell-based assays detected ROS scavenging activities of these extracts with EC50 values in the range of 0.6-5 mg/ml. All these assays indicated that the water extracts of Sangyod exerted significantly higher antioxidant activity than those of Dawk Mali 105, which exhibited only moderate to low activity. Furthermore, high levels of antioxidant activity of the water extracts of Sangyod were closely correlated to their flavonoid and phenolic contents, which were approximately 2.5 and 3 times higher, respectively, than those of Dawk Mali 105. CONCLUSION: These findings suggest that water extracts from colored brown rice or colored rice bran can be promising sources of potential natural antioxidants.
