Quercetin 3-sulfate is a plasma human metabolite of quercetin.Human metabolism of dietary flavonoids: Identification of plasma metabolites of quercetin. Andrea J. Day, Fred Mellon, Denis Barron, Géraldine Sarrazin, Michael R.A. Morgan and Gary Williamson, Free Radical Research, 2001, Vol. 35, No. 6, pages 941-952, Effect of quercetin conjugates on vascular permeability and expression of adhesion molecules. Mika Mochizuki, Katsuko Kajiya, Junji Terao, Kazuhiko Kaji, Shigenori Kumazawa, Tsutomu Nakayama and Kayoko Shimoi, BioFactors, Volume 22, Issue 1-4, pages 201–204, 2004, Metabolism of quercetin-7- and quercetin-3-glucuronides by an in vitro hepatic model: the role of human β-glucuronidase, sulfotransferase, catechol-O-methyltransferase and multi-resistant protein 2 (MRP2) in flavonoid metabolism. Karen A O’Leary, Andrea J Day, Paul W Needs, Fred A Mellon, Nora M O’Brien and Gary Williamson, Biochemical Pharmacology, Volume 65, Issue 3, 1 February 2003, pages 479-491, It is the sulfate conjugate of quercetin.
Biosynthesis and metabolism Quercetin 3-O-sulfate is produced directly in the perennial herb Flaveria chlorifolia from the flavonol, quercetin, by the enzyme flavonol 3-sulfotransferase. This uses the cofactor 3'-phosphoadenosine-5'-phosphosulfate (PAPS) and gives adenosine 3',5'-bisphosphate as a byproduct.
In this plant, quercetin-3-sulfate 3'-sulfotransferase converts quercetin 3-O-sulfate to the 3,3' isomer of the bissulfate and quercetin-3-sulfate 4'-sulfotransferase gives the 3,4' isomer. Further reactions lead to compounds including quercetin 3,3',7-trissulfate.
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