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Conversion of major soy isoflavone glucosides and aglycones in in vitro intestinal models
Author(s) -
Islam Mohammed A.,
Punt Ans,
Spenkelink Bert,
Murk Albertinka J.,
Rolaf van Leeuwen F. X.,
Rietjens Ivonne M. C. M.
Publication year - 2014
Publication title -
molecular nutrition and food research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.495
H-Index - 131
eISSN - 1613-4133
pISSN - 1613-4125
DOI - 10.1002/mnfr.201300390
Subject(s) - glucuronidation , chemistry , isoflavones , biochemistry , sulfation , incubation , in vitro , glucoside , biotransformation , enzyme , microsome , medicine , alternative medicine , pathology
Scope This study compares conversion of three major soy isoflavone glucosides and their aglycones in a series of in vitro intestinal models. Methods and results In an in vitro human digestion model isoflavone glucosides were not deconjugated, whereas studies in a C aco‐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 S 9. In incubations with rat intestinal S 9 lactase phlorizin hydrolase, glucocerebrosidase, and cytosolic broad‐specific β‐glucosidase all contribute significantly to deconjugation, whereas in incubations with human intestinal S 9 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. Conclusion 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.