Quercetin has been shown to decrease arterial blood pressure when given orally. Its has however low bioavailability.
Hence its metabolites could rather be responsible for this effect. In this study, we have tested three combinations of colonic metabolites of quercetin, 3,4-dihydroxyphenylacetic acid (DHPA), 4-methylcatechol (4MC), and 3-(3-hydroxyphenyl)propionic acid (3HPPA).
The effect of DHPA and 4MC was mild and very short-termed. A combination of DHPA with 3HPPA caused more pronounced effects, which were also rather short-lived.
The last combination of 3HPPA and 4MC caused a long-lasting effect. We suppose that certain combinations of quercetin metabolites have a more profound antihypertensive effect than single metabolites.