Quercetin, a potent and specific inhibitor of the human P-form phenolsulfotransferase

Abstract

The natural product quercetin was a potent inhibitor of the human P-form phenolsulfotransferase with an ic 50 value of 0.10 ± 0.03 μM (mean ± SEM; N = 5), which was three to four orders of magnitude more potent than its inhibition of other human sulfotransferases. The inhibition was noncompetitive with a K i value of 0.10 μM. The potency and mechanism of this inhibition appear similar to those of the current standard P-form inhibitor, 2,6-dichloro-4-nitrophenol. Among other flavonoids examined, kaempferol was found to have an ic 50 value of 0.39 ± 0.07 μM, naringenin 10.6 ± 1.6 μM and naringin 265 ± 90 μM (N = 3). These observations suggest the potential for clinically important pharmacologic and toxicologic interactions by flavonoid-containing foods and beverages.