Rice Bran Phenolic Compounds Regulate Genes Associated with Antioxidant and Anti-Inflammatory Activity in Human Umbilical Vein Endothelial Cells with Induced Oxidative Stress.

Oxidative stress, inflammation and endothelial dysfunction are associated with the development of cardiovascular and metabolic diseases. Phenolic extracts derived from rice bran (RB) are recognised to have antioxidant and anti-inflammatory potential. However, the underlying mechanisms remain unknown. Therefore, this study aimed to evaluate the ability of RB-derived phenolic extracts to modulate genes associated with antioxidant and anti-inflammatory pathways in human umbilical vein endothelial cells (HUVECs) under induced oxidative stress conditions. HUVECs under oxidative stress were treated with varying concentrations of RB phenolic extracts (25-250 µg/mL). Using quantitative real-time polymerase chain reaction, the expression of candidate genes that regulate antioxidant and anti-inflammatory pathways were determined. This included nuclear factor erythroid 2-related factor 2 ( Nrf2 ), nicotinamide adenine dinucleotide phosphate: quinone oxidoreductase 1 ( NQO1 ), heme oxygenase 1 ( HO1 ), nicotinamide adenine dinucleotide phosphate oxidase 4 ( NOX4 ), intercellular adhesion molecule 1 ( ICAM1 ), endothelial nitric oxide synthase ( eNOS ), ectonucleoside triphosphate diphosphohydrolase 1 ( CD39 ) and ecto-5'-nucleotidase ( CD73 ). Phenolic extracts derived from RB down-regulated the expression of four genes, ICAM1 , CD39 , CD73 and NOX4 and up-regulated the expression of another four genes, Nrf2 , NQO1 , HO1 and eNOS , indicating an antioxidant/ anti-inflammatory effect for RB against endothelial dysfunction.