Studies of the in vitro intestinal metabolism of isoflavones aid in the identification of their urinary metabolites

Satu-Maarit Heinonen (Corresponding Author), Kristiina Wähälä, Kirsi-Helena Liukkonen, Anna-Marja Aura, Kaisa Poutanen, Herman Adlercreutz

Research output: Contribution to journalArticleScientificpeer-review

31 Citations (Scopus)

Abstract

Soy isoflavones have recently gained considerable interest due to their possible health benefits. However, detailed studies on the metabolism of isoflavones are lacking. The aims of the investigation presented here were (1) to study the in vitro intestinal metabolism of isoflavones and their hydroxylated analogues 3'-OH-daidzein, 6-OH-daidzein, 8-OH-daidzein, and 3'-OH-genistein and (2) to characterize the structures of some earlier identified urinary metabolites of soy isoflavones, for which no authentic reference compounds have been available. Isoflavone standards (1-2 mg) were fermented with human fecal flora (16.7%) for 24 h. Metabolites formed during the fermentation were tentatively identified by interpretation of the mass spectra of trimethylsilylated compounds obtained by GC-MS. Compounds having hydroxyl groups at 5-position (i.e., genistein and 3'-OH-genistein) were completely converted to metabolites that could not be detected by the methods used in this study. The metabolism of daidzein and its hydroxylated analogues, 3'-OH-daidzein, 6-OH-daidzein, and 8-OH-daidzein, occurred to a much lesser extent. Minor amounts of reduced metabolites (i.e., isoflavanones and -methyldeoxybenzoins) of these compounds were tentatively identified in fermentation extracts. The retention times and the mass spectra of reduced isoflavone metabolites, obtained from in vitro fermentations of pure compounds, were utilized to identify unknown urinary metabolites of soy isoflavones. Four novel isoflavone metabolites were identified in human urine collected after soy supplementation: 3' '-OH-O-desmethylangolensin, 3',4',7-trihydroxyisoflavanone, 4',7,8-trihydroxyisoflavanone, and 4',6,7-trihydroxyisoflavanone.
Original languageEnglish
Pages (from-to)2640 - 2646
JournalJournal of Agricultural and Food Chemistry
Volume52
Issue number9
DOIs
Publication statusPublished - 2004
MoE publication typeA1 Journal article-refereed

Fingerprint

Isoflavones
isoflavones
Metabolites
daidzein
Metabolism
in vitro studies
metabolites
metabolism
genistein
Genistein
Fermentation
fermentation
hydroxide ion
In Vitro Techniques
Insurance Benefits
Hydroxyl Radical
urine
flora
Health
Urine

Keywords

  • Daidzein
  • genistein
  • soy
  • isoflavone
  • metabolism

Cite this

Heinonen, Satu-Maarit ; Wähälä, Kristiina ; Liukkonen, Kirsi-Helena ; Aura, Anna-Marja ; Poutanen, Kaisa ; Adlercreutz, Herman. / Studies of the in vitro intestinal metabolism of isoflavones aid in the identification of their urinary metabolites. In: Journal of Agricultural and Food Chemistry. 2004 ; Vol. 52, No. 9. pp. 2640 - 2646.
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abstract = "Soy isoflavones have recently gained considerable interest due to their possible health benefits. However, detailed studies on the metabolism of isoflavones are lacking. The aims of the investigation presented here were (1) to study the in vitro intestinal metabolism of isoflavones and their hydroxylated analogues 3'-OH-daidzein, 6-OH-daidzein, 8-OH-daidzein, and 3'-OH-genistein and (2) to characterize the structures of some earlier identified urinary metabolites of soy isoflavones, for which no authentic reference compounds have been available. Isoflavone standards (1-2 mg) were fermented with human fecal flora (16.7{\%}) for 24 h. Metabolites formed during the fermentation were tentatively identified by interpretation of the mass spectra of trimethylsilylated compounds obtained by GC-MS. Compounds having hydroxyl groups at 5-position (i.e., genistein and 3'-OH-genistein) were completely converted to metabolites that could not be detected by the methods used in this study. The metabolism of daidzein and its hydroxylated analogues, 3'-OH-daidzein, 6-OH-daidzein, and 8-OH-daidzein, occurred to a much lesser extent. Minor amounts of reduced metabolites (i.e., isoflavanones and -methyldeoxybenzoins) of these compounds were tentatively identified in fermentation extracts. The retention times and the mass spectra of reduced isoflavone metabolites, obtained from in vitro fermentations of pure compounds, were utilized to identify unknown urinary metabolites of soy isoflavones. Four novel isoflavone metabolites were identified in human urine collected after soy supplementation: 3' '-OH-O-desmethylangolensin, 3',4',7-trihydroxyisoflavanone, 4',7,8-trihydroxyisoflavanone, and 4',6,7-trihydroxyisoflavanone.",
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Studies of the in vitro intestinal metabolism of isoflavones aid in the identification of their urinary metabolites. / Heinonen, Satu-Maarit (Corresponding Author); Wähälä, Kristiina; Liukkonen, Kirsi-Helena; Aura, Anna-Marja; Poutanen, Kaisa; Adlercreutz, Herman.

In: Journal of Agricultural and Food Chemistry, Vol. 52, No. 9, 2004, p. 2640 - 2646.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Studies of the in vitro intestinal metabolism of isoflavones aid in the identification of their urinary metabolites

AU - Heinonen, Satu-Maarit

AU - Wähälä, Kristiina

AU - Liukkonen, Kirsi-Helena

AU - Aura, Anna-Marja

AU - Poutanen, Kaisa

AU - Adlercreutz, Herman

PY - 2004

Y1 - 2004

N2 - Soy isoflavones have recently gained considerable interest due to their possible health benefits. However, detailed studies on the metabolism of isoflavones are lacking. The aims of the investigation presented here were (1) to study the in vitro intestinal metabolism of isoflavones and their hydroxylated analogues 3'-OH-daidzein, 6-OH-daidzein, 8-OH-daidzein, and 3'-OH-genistein and (2) to characterize the structures of some earlier identified urinary metabolites of soy isoflavones, for which no authentic reference compounds have been available. Isoflavone standards (1-2 mg) were fermented with human fecal flora (16.7%) for 24 h. Metabolites formed during the fermentation were tentatively identified by interpretation of the mass spectra of trimethylsilylated compounds obtained by GC-MS. Compounds having hydroxyl groups at 5-position (i.e., genistein and 3'-OH-genistein) were completely converted to metabolites that could not be detected by the methods used in this study. The metabolism of daidzein and its hydroxylated analogues, 3'-OH-daidzein, 6-OH-daidzein, and 8-OH-daidzein, occurred to a much lesser extent. Minor amounts of reduced metabolites (i.e., isoflavanones and -methyldeoxybenzoins) of these compounds were tentatively identified in fermentation extracts. The retention times and the mass spectra of reduced isoflavone metabolites, obtained from in vitro fermentations of pure compounds, were utilized to identify unknown urinary metabolites of soy isoflavones. Four novel isoflavone metabolites were identified in human urine collected after soy supplementation: 3' '-OH-O-desmethylangolensin, 3',4',7-trihydroxyisoflavanone, 4',7,8-trihydroxyisoflavanone, and 4',6,7-trihydroxyisoflavanone.

AB - Soy isoflavones have recently gained considerable interest due to their possible health benefits. However, detailed studies on the metabolism of isoflavones are lacking. The aims of the investigation presented here were (1) to study the in vitro intestinal metabolism of isoflavones and their hydroxylated analogues 3'-OH-daidzein, 6-OH-daidzein, 8-OH-daidzein, and 3'-OH-genistein and (2) to characterize the structures of some earlier identified urinary metabolites of soy isoflavones, for which no authentic reference compounds have been available. Isoflavone standards (1-2 mg) were fermented with human fecal flora (16.7%) for 24 h. Metabolites formed during the fermentation were tentatively identified by interpretation of the mass spectra of trimethylsilylated compounds obtained by GC-MS. Compounds having hydroxyl groups at 5-position (i.e., genistein and 3'-OH-genistein) were completely converted to metabolites that could not be detected by the methods used in this study. The metabolism of daidzein and its hydroxylated analogues, 3'-OH-daidzein, 6-OH-daidzein, and 8-OH-daidzein, occurred to a much lesser extent. Minor amounts of reduced metabolites (i.e., isoflavanones and -methyldeoxybenzoins) of these compounds were tentatively identified in fermentation extracts. The retention times and the mass spectra of reduced isoflavone metabolites, obtained from in vitro fermentations of pure compounds, were utilized to identify unknown urinary metabolites of soy isoflavones. Four novel isoflavone metabolites were identified in human urine collected after soy supplementation: 3' '-OH-O-desmethylangolensin, 3',4',7-trihydroxyisoflavanone, 4',7,8-trihydroxyisoflavanone, and 4',6,7-trihydroxyisoflavanone.

KW - Daidzein

KW - genistein

KW - soy

KW - isoflavone

KW - metabolism

U2 - 10.1021/jf030681s

DO - 10.1021/jf030681s

M3 - Article

VL - 52

SP - 2640

EP - 2646

JO - Journal of Agricultural and Food Chemistry

JF - Journal of Agricultural and Food Chemistry

SN - 0021-8561

IS - 9

ER -