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Distribution and molecular forms of soy isoflavones in organs/tissues of rats and pigs
Author(s) -
Gu Liwei,
House Suzanne E,
Prior Ronald L.,
Badger Thomas M.
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a598-a
Subject(s) - daidzein , equol , genistein , isoflavones , aglycone , chemistry , metabolite , phytoestrogens , medicine , endocrinology , biochemistry , food science , biology , glycoside , estrogen , organic chemistry
In order to assess the potential risks and benefits of soy isoflavones and mechanisms by which health effects occur, it is essential to have a complete understanding of their concentrations and molecular forms in target tissues. Sprague‐Dawley rats (n=6) and piglets (n=3) were fed soy protein isolates. Thirteen or twenty organs/tissues were collected from rats or pigs for isoflavone analysis. Rats were perfused and pig tissues were rinsed with 0.09% saline to remove residue blood. A new extraction method enabled us to measure genistein, daidzein, O‐DMA, and equol, including aglycone and conjugated forms. Total isoflavone contents varied markedly in different organs of rats (genistein or daidzein, 0.01–14 nmol/g; equol, 0.06–47 nmol/g). The lowest contents were found in brain, spleen, and fat; and the highest in intestines and colon. Approximately 22–45% of total isoflavones were free aglycones, with 21–66% being glucuronides and reminders (14%–42%) being sulfates in rat organs. Total isoflavone contents in pig organs/tissues ranged from 0 to 5.3 nmol/g and 0.4 to 14 nmol/g for genistein and daidzein, respectively (lowest in lung, highest in intestines). The organs of rats and pigs differed in contents of isoflavones as well as proportion of aglycones and conjugates. All rat organs contained equol as the major metabolite of daidzein, whereas pig tissues contained very low level of equol (0–0.2 nmol/g). This study delineated isoflavone profiles in tissues and identified new target tissues of isoflavones, which may help to understand their mechanisms of action in vivo. (USDA CRIS 6251‐51000‐004‐06S)