Higher plasma quercetin levels following oral administration of an onion skin extract compared with pure quercetin dihydrate in humans

• Published in: European journal of nutrition Vol. 56; no. 1; pp. 343 - 353
• Main Authors: Burak, Constanze, Brüll, Verena, Langguth, Peter, Zimmermann, Benno F., Stoffel-Wagner, Birgit, Sausen, Udo, Stehle, Peter, Wolffram, Siegfried, Egert, Sarah
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.02.2017; Springer Nature B.V
• Subjects: Administration, Oral; Adult; Biological Availability; blood sampling; Chemistry; Chemistry and Materials Science; Cross-Over Studies; Disaccharides - administration & dosage; Disaccharides - blood; Disaccharides - pharmacokinetics; Dose-Response Relationship, Drug; enzymatic treatment; Female; fluorescence; high performance liquid chromatography; Humans; isorhamnetin; Male; men; Nutrition; onions; Onions - chemistry; oral administration; Original Contribution; pharmacokinetics; Plant Extracts - administration & dosage; Plant Extracts - blood; Plant Extracts - pharmacokinetics; Powders; quercetin; Quercetin - administration & dosage; Quercetin - analogs & derivatives; Quercetin - blood; Quercetin - pharmacokinetics; Single-Blind Method; women; Young Adult; Bioavailability; Onion; Human study; Quercetin
• ISSN: 1436-6207; 1436-6215; 1435-1293; 1436-6215
• DOI: 10.1007/s00394-015-1084-x

Purpose To investigate the plasma kinetics of quercetin derived from hard capsules filled with onion skin extract powder or quercetin dihydrate in humans. Methods In a randomized, single-blind, diet-controlled crossover study, 12 healthy subjects (six men and six women) aged 21–33 years were administered a single oral supra-nutritional dose of approximately 163 mg quercetin derived from onion skin extract powder (containing 95.3 % of total flavonoids as quercetin aglycone) or quercetin dihydrate (134 mg quercetin aglycone equivalent). Blood samples were collected before and during a 24-h period after quercetin administration. The concentrations of quercetin and its two monomethylated derivatives, isorhamnetin (3′- O -methyl quercetin), and tamarixetin (4′- O -methyl quercetin), were measured using HPLC with fluorescence detection after plasma enzymatic treatment. Results The systemic availability, determined by comparing the plasma concentration–time curves of quercetin, was 4.8 times higher, and the maximum plasma concentration ( C max ) was 5.4 times higher after ingestion of the onion skin extract than after ingestion of pure quercetin dihydrate. By contrast, t max did not differ significantly between the two formulations. The C max values for isorhamnetin and tamarixetin were 3.8 and 4.4 times higher, respectively, after administration of onion skin extract than after pure quercetin dihydrate. The plasma kinetics of quercetin were not significantly different in men and women. Conclusion Quercetin aglycone derived from onion skin extract powder is significantly more bioavailable than that from quercetin dihydrate powder filled hard capsules.