Pure dietary flavonoids quercetin and (−)-epicatechin augment nitric oxide products and reduce endothelin-1 acutely in healthy men

Abstract

Background: Dietary flavonoids may improve endothelial function and ultimately lead to beneficial cardiovascular effects. Objective: The objective was to assess whether pure dietary flavonoids can modulate nitric oxide and endothelin-1 production and thereby improve endothelial function. Design: A randomized, placebo-controlled, crossover trial in 12 healthy men was conducted to compare the acute effects of the oral administration of 200 mg quercetin, (Ҁ)-epicatechin, or epigallocatechin gallate on nitric oxide, endothelin-1, and oxidative stress after nitric oxide production was assessed via the measurement of plasma S-nitrosothiols and plasma and urinary nitrite and nitrate concentrations. The effects on oxidative stress were assessed by measuring plasma and urinary F 2 -isoprostanes. Plasma and urinary concentrations of quercetin, (Ҁ)-epicatechin, and epigallocatechin gallate were measured to establish the absorption of these flavonoids. Results: Relative to water (control), quercetin and (Ҁ)-epicatechin resulted in a significant increase in plasma S-nitrosothiols, plasma nitrite, and urinary nitrate concentrations (P 0.05), but not in plasma nitrate or urinary nitrite. Epigallocatechin gallate did not alter any of the measures of nitric oxide production. Quercetin and (Ҁ)-epicatechin resulted in a significant reduction in plasma endothelin-1 concentration (P 0.05), but only quercetin significantly decreased the urinary endothelin-1 concentration. None of the 3 treatments significantly changed plasma or urinary F 2 -isoprostane concentrations. Significant increases in the circulating concentrations of the 3 flavonoids were observed (P 0.05) after the corresponding treatment. Conclusions: Dietary flavonoids, such as quercetin and (Ҁ)-epicatechin, can augment nitric oxide status and reduce endothelin-1 concentrations and may thereby improve endothelial function.

Apple as a Source of Dietary Phytonutrients: Bioavailability and Evidence of Protective Effects against Human Cardiovascular Disease

“…Dietary components, such as particular flavonoids can augment NO status acutely and in so doing enhance endothelial function. Flavonoids increase endogenous endothelial NO production and/or reduce breakdown [52]. These effects may contribute to the benefits of flavonoid-rich foods and beverages on cardiovascular health [53].…”

Association of flavonoid-rich foods and flavonoids with risk of all-cause mortality

“…Much of the beneficial effects of these foods have been attributed to 30 their high content of biologically active flavonoids, which have been shown to improve nitric 31 oxide homeostasis and endothelial function, and reduce platelet aggregation and oxidative 32 stress [8][9][10][11][12][13] . Flavonoids are also thought to play roles in inactivating carcinogens, inducing 33 antiproliferation, cell cycle arrest and apoptosis, and inhibiting angiogenesis 14 .…”

Spleen content of selected polyphenols, splenocytes morphology and function in mice fed Rhodiola kirilowii extracts during pregnancy and lactation

“…Their antioxidant capacity is due to their stabilizing effect on the cell membranes. Both quercetin and (-)-epicatechin can augment nitric oxide status and reduce endothelin-1 concentrations (Loke et al 2008). Catechin and quercetin significantly reduced organophosphorus insecticide chlorpyrifo-induced hepatotoxicity in rats (Uzun and Kalender 2013).…”