Abstract
The roles of isoflavones in the prevention of several hormone-dependent cancers and osteoporosis are of great interest. Despite many pharmacokinetics studies of the isoflavones, the actual types of conjugates circulating in the body and the position(s) of conjugation sites on the flavone skeleton are still uncertain because, in general, conjugated compounds in biological fluids have been evaluated by measuring the free aglycones obtained after selective enzymatic hydrolysis. Using an high-performance (HPLC)-UV-diode-array detector (DAD) method combined with solid-phase extraction, we have obtained HPLC profiles of isoflavone glycosides [daidzin (Din) and genistin (Gin)] and of intact isoflavone metabolites in human plasma: daidzein, genistein, daizein-7-glucuronide, daidzein-4′-glucuronide, genistein-7-glucuronide, genistein-4′-glucuronide, daidzein-7-sulfate, daidzein-4′-sulfate, genistein-7-sulfate, and genistein-4′-sulfate. We investigated the plasma profile of intact isoflavone metabolites in plasma obtained 1 to-7 h after orally administration of 50 g of kinako (baked soybean powder) to two healthy volunteers. The results of DAD analysis indicated that the main isoflavone metabolite peaks were identified on the HPLC chromatogram. Furthermore, the intact glycosides Din and Gin were detected in 1-h plasma samples by their positive electrospray ionization mass spectra, demonstrating that the glycosides Din and Gin can be absorbed from the gut.
Footnotes
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This work was supported in part by a Project Research Grant from Kyorin University.
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Article, publication date, and citation information can be found at http://dmd.aspetjournals.org.
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doi:10.1124/dmd.108.021006.
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ABBREVIATIONS: Din, daidzin; Gin, genistin; Dein, daidzein; Gein, genistein; HPLC, high-performance liquid chromatography; LC, liquid chromatography; MS, mass spectrometry; DAD, diode-array detector; D-7-S, daidzein-7-sulfate; D-4′-S, daidzein-4′-sulfate; G-7-S, genistein-7-sulfate; G-4′-S, genistein-4′-sulfate; D-7-G, daidzein-7-glucuronide; G-7-G, genistein-7-glucuronide; NMR, nuclear magnetic resonance; DMSO, dimethyl sulfoxide; ESI, electrospray ionization; UGT, UDP-glucuronosyl transferase; D-4′-G, daidzein-4′-glucuronide; G-4′-G, genistein-4′-glucuronide; RT, retention time; MS/MS or MS/MS/MS, tandem mass spectrometry.
- Received February 14, 2008.
- Accepted April 23, 2008.
- The American Society for Pharmacology and Experimental Therapeutics
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