title: Conversion of major soy isoflavone glucosides and aglycones in in vitro intestinal models.
abstract: METHODS
  This study compares conversion of three major soy isoflavone glucosides and their aglycones in a series of in vitro intestinal models.
  
  
  RESULTS
  In an in vitro human digestion model isoflavone glucosides were not deconjugated, whereas studies in a Caco-2 transwell model confirmed that deconjugation is essential to facilitate transport across the intestinal barrier. Deconjugation was shown upon incubation of the isoflavone glucosides with rat as well as human intestinal S9. In incubations with rat intestinal S9 lactase phlorizin hydrolase, glucocerebrosidase, and cytosolic broad-specific β-glucosidase all contribute significantly to deconjugation, whereas in incubations with human intestinal S9 deconjugation appeared to occur mainly through the activity of broad-specific β-glucosidase. Species differences in glucuronidation and sulfation were limited and generally within an order of magnitude with 7-O-glucuronides being the major metabolites for all three isoflavone aglycones and the glucuronidation during first pass metabolism being more efficient in rats than in humans. Comparison of the catalytic efficiencies reveals that deconjugation is less efficient than conjugation confirming that aglycones are unlikely to enter the systemic circulation.
  
  
  CONCLUSIONS
  Altogether, the data point at possible differences in the characteristics for intestinal conversion of the major soy isoflavones between rat and human, especially with respect to their deconjugation.
authors.affiliation: Division of Toxicology, Wageningen University, Wageningen, The Netherlands.
authors.forename: Mohammed A
authors.initials: MA
authors.lastname: Islam
authors.forename: Ans
authors.initials: A
authors.lastname: Punt
authors.forename: Bert
authors.initials: B
authors.lastname: Spenkelink
authors.forename: Albertinka J
authors.initials: AJ
authors.lastname: Murk
authors.forename: F X
authors.initials: FX
authors.lastname: Rolaf van Leeuwen
authors.forename: Ivonne M C M
authors.initials: IM
authors.lastname: Rietjens
mesh_terms: D000818:Animals; D001682:Biological Availability; D001692:Biological Transport; D018938:Caco-2 Cells / Q000187:drug effects / Q000378:metabolism; D019587:Dietary Supplements / Q000032:analysis; D004063:Digestion; D005960:Glucosides / Q000493:pharmacokinetics; D006801:Humans; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000378:metabolism*; D007529:Isoflavones / Q000032:analysis / Q000493:pharmacokinetics*; D008099:Liver / Q000378:metabolism; D051381:Rats; D013025:Glycine max / Q000737:chemistry*
chemical_list: D005960:Glucosides; D007529:Isoflavones; C040641:genistin; C013908:daidzin; C433283:glycitin
keywords: Bioavailability; Conjugation; Deconjugation; In vitro models; Isoflavones