O31 Can colonic metabolites be responsible for the hypotensive effect of orally given quercetin

Epidemiologic data suggest protective effects of higher flavonoid intake on cardiovascular diseases. Some human and animal studies reported a decrease in arterial blood pressure after quercetin administration. The mechanism of this effect is not yet well-understood since the closes metabolites of quercetin are either inactive or present in very low plasma concentrations. In this study, a series of colonic quercetin metabolites was analysed. First, the effects on isolated rat aorta were evaluated. Subsequently, the efficient metabolites were also tested in vivo on normotensive and hypertensive rats and in vitro on mesenteric artery. Screening in aorta clearly showed 3-(3-hydroxyphenyl) propionic acid to be the most efficient. These results were confirmed in vivo , where this metabolite decreased arterial blood pressure in hypertensive rats. Further mechanistic experiments confirmed that this effect was based on vasodilation of vessels, no negative effects on the heart were observed. Interestingly, additional experiments showed that two other metabolites with lower effects in the aorta, were also able to reduce blood pressure in rats. Interestingly, these metabolites seemed to have better effects on resistance vessels than on aorta in comparison to 3-(3-hydroxyphenyl) propionic acid. Some colonic metabolites of quercetin are able to decrease the arterial blood pressure in rats. Future experiments are necessary to verify whether these effects can be long-lasting and clinically relevant.