Protective effects of luteolin on the venous endothelium.

Luteolin is a flavonoid with antioxidant properties already demonstrated in studies related to inflammation, tumor, and cardiovascular processes; however, there are no available information regarding its antioxidant effects at the venous endothelial site. We investigated the effects of luteolin (10, 20, and 50 μmol/L) in cultures of rat venous endothelial cells. Nitric oxide (NO) and reactive oxygen species (ROS) were analyzed by fluorimetry; 3-nitrotyrosine (3-NT) residues were evaluated by immunofluorescence, and prostacyclin (PGI2) release was investigated by colorimetry. Intracellular NO levels were significantly enhanced after 10 min of luteolin incubation, with a parallel decrease in ROS generation. These results were accompanied by a significant reduction in the expression of 3-NT residues and enhanced PGI2 rates. Therefore, luteolin is effective in reducing ROS thereby improving NO availability in venous endothelial cells. Besides, luteolin-induced decrease in 3-NT residues may correlate with the enhancement in endothelial PGI2 bioavailability. These findings suggest the future application of this flavonoid as a protective agent by improving endothelial function in several circulatory disorders related to venous insufficiency.