ABSTRACT
Objective: To study the inhibitory effect of rice bran extracts of Thai black Kam Muang and red Hawm Dawk Mali Deang on oxidative stress factors including superoxide (O2?-), nitric oxide (NO?), and inducible nitric oxide synthase (iNOS). Methods: Bran extracts (40% ethanol) of Kam Muang and Hawm Dawk Mali Deang were obtained and evaluated for in vitro 2-2′-azino-di-(3-ethylbenzthiazoline sulfonate) (ABTS) and NO? scavenging activity. Their inhibitory effects on cellular O2?- and NO? were measured in phorbol 12-myristate 13-acetate-stimulated neutrophil-like HL-60 cells and lipopolysaccharide-stimulated RAW264.7 macrophages, respectively, and their viability was monitored using the MTT assay. The effect on iNOS expression was also assessed by the Western blotting assay. Total contents of phenolics, flavonoids, and subtypes were also determined. Results: Hawm Dawk Mali Deang exhibited about 3.5-fold greater cellular O2?- inhibitory activity than Kam Muang [EC50 values of (23.57±4.54) and (81.98±1.45) μg/mL, respectively] in phorbol 12-myristate 13-acetate-stimulated HL-60 cells. Hawm Dawk Mali Deang exhibited about 2-fold higher in vitro ABTS?+ and NO? scavenging activity than Kam Muang, but it exerted cellular NO? inhibitory activity of only about 26% (undetermined EC50 value) in lipopolysaccharide-stimulated RAW264.7 cells. Conversely, Kam Muang exerted potent cellular NO? inhibitory activity [EC50 value: (281.13±59.18) μg/mL] and dose-dependently decreased iNOS levels. No cytotoxicity of both extracts was detected in both cell types. As for corresponding contents, Hawm Dawk Mali Deang contained higher contents of phenolics and flavonoids than Kam Muang. Moreover, Kam Muang and Hawm Dawk Mali Deang had a high content of total anthocyanins [(14.73±0.52) mg C3GE/g of extract] and total proanthocyanidins [(115.13±1.47) mg CE/g of extract], respectively. Conclusions: Based on these data, bran extracts of Thai black Kam Muang and red rice Hawm Dawk Mali Deang can help lower oxidative stress and inflammation attributed partly to O2?-and NO?.
ABSTRACT
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.