Metabolites of polyphenols preserve indices of endothelial cell nitric oxide bioavailability under glucotoxic conditions (372.6)

Abstract

We hypothesized that biological metabolites of quercetin, resveratrol, and grape seed extract previously identified in human plasma can prevent impairment of nitric oxide (NO) bioavailability due to glucotoxic conditions (e.g. Type 1 or 2 diabetes).Human aortic endothelial cells were treated for 24 h with 2μΜ Quercetin‐3‐O‐glucoronide, 5μΜ Piceatannol, or 1μΜ 3‐Hydroproponoic acid. Cells were next exposed to normal (5mM) or high (25mM) glucose for 48h, then treated with insulin (100nM, 10 min) to stimulate NO production.In the absence of polyphenols, insulin stimulation increased (P<0.05) indices of NO production, phosphorylated to total Akt (p‐AktSer473:Akt), and endothelial nitric oxide synthase (p‐eNOSser1177:eNOS) in cells grown in 5mM but not 25mM glucose. Pretreatment of cells with polyphenol metabolites prior to 25mM glucose exposure preserved insulin stimulated increases (P<0.05) in NO, p‐AktSer473:Akt and p‐eNOSser1177:eNOS. These effects may be secondary to oxidative stress as elevations (P<0.05) in reactive oxygen and nitrogen species in cells treated with 25mM glucose were completely prevented by all polyphenol metabolites.These data indicate that biological metabolites of quercetin, resveratrol, and grape seed extract protected against gluocotoxic impairment of insulin dependent NO bioavailability, and preserved the insulin ‐ Akt ‐ eNOS signaling axis.