title: Bioavailabilities of quercetin-3-glucoside and quercetin-4'-glucoside do not differ in humans.
abstract: The flavonoid quercetin is an antioxidant which occurs in foods mainly as glycosides. The sugar moiety in quercetin glycosides affects their bioavailability in humans. Quercetin-3-rutinoside is an important form of quercetin in foods, but its bioavailability in humans is only 20% of that of quercetin-4'-glucoside. Quercetin-3-rutinoside can be transformed into quercetin-3-glucoside by splitting off a rhamnose molecule. We studied whether this 3-glucoside has the same high bioavailability as the quercetin-4'-glucoside. To that end we fed five healthy men and four healthy women (19-57 y) a single dose of 325 micromol of pure quercetin-3-glucoside and a single dose of 331 micromol of pure quercetin-4'-glucoside and followed the plasma quercetin concentrations. The bioavailability was the same for both quercetin glucosides. The mean peak plasma concentration of quercetin was 5.0+/-1.0 micromol/L (+/-SE) after subjects had ingested quercetin-3-glucoside and 4.5+/-0.7 micromol/L after quercetin-4'-glucoside consumption. Peak concentration was reached 37 +/-12 min after ingestion of quercetin-3-glucoside and 27+/-5 min after quercetin-4'-glucoside. Half-life of elimination of quercetin from blood was 18.5+/-0.8 h after ingestion of quercetin-3-glucoside and 17.7+/-0.9 h after quercetin-4'-glucoside. We conclude that quercetin glucosides are rapidly absorbed in humans, irrespective of the position of the glucose moiety. Conversion of quercetin glycosides into glucosides is a promising strategy to enhance bioavailability of quercetin from foods.
authors.affiliation: Division of Human Nutrition and Epidemiology, Wageningen University and Research Centre, 6700 EV, Wageningen, The Netherlands.
authors.forename: M R
authors.initials: MR
authors.lastname: Olthof
authors.forename: P C
authors.initials: PC
authors.lastname: Hollman
authors.forename: T B
authors.initials: TB
authors.lastname: Vree
authors.forename: M B
authors.initials: MB
authors.lastname: Katan
mesh_terms: D000284:Administration, Oral; D000328:Adult; D019540:Area Under Curve; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006207:Half-Life; D006801:Humans; D008297:Male; D008875:Middle Aged; D010276:Parasympatholytics / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics*; D010936:Plant Extracts / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics; D011794:Quercetin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics; D013329:Structure-Activity Relationship
chemical_list: D010276:Parasympatholytics; D010936:Plant Extracts; C016527:isoquercitrin; D011794:Quercetin; C080613:spiraeoside