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Quercetin and isorhamnetin prevent endothelial dysfunction, superoxide production, and overexpression of p47phox induced by angiotensin II in rat aorta

Endothelial dysfunction is a systemic pathological state of the inner lining of our blood vessels with an imbalance between vasodilating and vasoconstricting substances. Endothelial dysfunction plays an important role in the development of atherosclerosis. The condition is associated with reduced anticoagulant properties, increased production of adhesion molecules, chemokines and reactive oxygen species production, all of which play important roles in the development of atherosclerosis. Endothelial dysfunction is associated with decreased NO bioavailability, which is the result of reduced NO production or increased inactivation of NO by reactive oxygen species.



Epidemiological studies have demonstrated the protective role of flavonols against coronary heart disease. Previous rodent studies showed that the flavonols quercetin relaxed vascular smooth muscle and reduces blood pressure an endothelial dysfunction in experimental models of hypertension.

A group of researchers lead by Sanchez at the University of Granada explored the effect of quercetin and isorhamnetin on the endothelial function in incubated aorta rings treated with angiotensin II, a compound that increases blood pressure, constricts blood vessels, induces vascular smooth muscle hypertrophy and expression of many vasoactive and inflammatory substances. Previous studies have shown that angiotensin activates NADPH oxidases in vascular smooth muscle cells by inducing phosphorylation of P47 and production if P47 and NADPH oxidase subunits. They found that both quercetin and isorhamnetin (a quercetin metabolite) prevented angiotensin II induced endothelial dysfunctioning, overexpression of P47 and increased production of superoxide anion. The scientists believe that 2 mechanisms might be involved in the protective effect of quercetin. The phytochemical could act as antioxidant by removing reactive oxygen species, thereby reducing the production of NADPH oxidase subunits, or it could act as a protein kinase inhibitor. It is important to note that quercetin was effective at very low levels which can be achieved in human plasma after intake of food containing this phytochemical.


Source: Sanchez M, Lodi F, Vera R, Villar IC, Cogolludo A, Jimenez R, Moreno L, Romero M, Tamargo J, Perez-Vizcaino F, Duarte J. Quercetin and isorhamnetin prevent endothelial dysfunction, superoxide production, and overexpression of p47phox induced by angiotensin II in rat aorta. J Nutr. 2007 Apr;137(4):910-5


 
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