Structural Elucidation of Hydroxylated Metabolites of the Isoflavan Equol by Gas Chromatography-Mass Spectrometry and High-Performance Liquid Chromatography-Mass Spectrometry

Rüfer, C.E.; Glatt, Hansruedi; Kulling, Sabine E.

doi:10.1124/dmd.105.004929

Cited by 50 publications

(36 citation statements)

References 27 publications

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“…On the other hand, 5-hydroxy-equol may have escaped detection because a standard reference compound is not commercially available. Different hydroxyl-substituted equol derivatives are products of phase I metabolism of equol by host enzymes (37). Interestingly, 5-hydroxy-equol was reported to show an antioxidant activity superior to that of genistein (2).…”

Section: Resultsmentioning

confidence: 99%

Conversion of Daidzein and Genistein by an Anaerobic Bacterium Newly Isolated from the Mouse Intestine

Matthies¹,

Clavel

Gütschow

et al. 2008

Appl Environ Microbiol

121

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The metabolism of isoflavones by gut bacteria plays a key role in the availability and bioactivation of these compounds in the intestine. Daidzein and genistein are the most common dietary soy isoflavones. While daidzein conversion yielding equol has been known for some time, the corresponding formation of 5-hydroxyequol from genistein has not been reported previously. We isolated a strictly anaerobic bacterium (Mt1B8) from the mouse intestine which converted daidzein via dihydrodaidzein to equol as well as genistein via dihydrogenistein to 5-hydroxy-equol. Strain Mt1B8 was a gram-positive, rod-shaped bacterium identified as a member of the Coriobacteriaceae. Strain Mt1B8 also transformed dihydrodaidzein and dihydrogenistein to equol and 5-hydroxy-equol, respectively. The conversion of daidzein, genistein, dihydrodaidzein, and dihydrogenistein in the stationary growth phase depended on preincubation with the corresponding isoflavonoid, indicating enzyme induction. Moreover, dihydrogenistein was transformed even more rapidly in the stationary phase when strain Mt1B8 was grown on either genistein or daidzein. Growing the cells on daidzein also enabled conversion of genistein. This suggests that the same enzymes are involved in the conversion of the two isoflavones.

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Section: Resultsmentioning

confidence: 99%

Conversion of Daidzein and Genistein by an Anaerobic Bacterium Newly Isolated from the Mouse Intestine

Matthies¹,

Clavel

Gütschow

et al. 2008

Appl Environ Microbiol

121

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“…In the case of isoflavones, this fragmentation accounts for less than 10% of the relative intensity in the mass spectrum. However, after hydrogenation of the isoflavone molecule, this cleavage is facilitated and the 4-methylphenol cation constitutes a major fragment (relative intensity460%) [33,34].…”

Section: Identification Of Dhimentioning

confidence: 99%

The red clover isoflavone irilone is largely resistant to degradation by the human gut microbiota

Braune

Maul

Schebb

et al. 2009

Mol. Nutr. Food Res.

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Intestinal bacteria may influence bioavailability and physiological activity of dietary isoflavones. We therefore investigated the ability of human intestinal microbiota to convert irilone and genistein in vitro. In contrast to genistein, irilone was largely resistant to transformation by fecal slurries of ten human subjects. The fecal microbiota converted genistein to dihydrogenistein, 6'-hydroxy-O-desmethylangolensin, and 2-(4-hydroxyphenyl)-propionic acid. However, considerable interindividual differences in the rate of genistein degradation and the pattern of metabolites formed from genistein were observed. Only one metabolite, namely dihydroirilone, was formed from irilone in minor amounts. In further experiments, Eubacterium ramulus, a prevalent flavonoid-degrading species of the human gut, was tested for transformation of irilone. In contrast to genistein, irilone was not converted by E. ramulus. Irilone only differs from genistein by a methylenedioxy group attached to the A-ring of the isoflavone skeleton. This substitution obviously restricts the degradability of irilone by human intestinal bacteria.

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“…In recent years, new techniques were applied to identify and characterize the metabolites, such as gas chromatography-MS, LC-MS (Rüfer et al, 2006;Xu et al, 2006), LC/NMR (Mutlib and Shockcor, 2003), NMR (Zhang et al, 2004;Zeng et al, 2007), and stable isotopes. In our study, three groups of positional isomers (M5, M6, M7, and M8; M1 and M2; and M3 and M4) were obtained.…”

Section: Discussionmentioning

confidence: 99%

Metabolism of Echinacoside, a Good Antioxidant, in Rats: Isolation and Identification of Its Biliary Metabolites

Jia

H²,

Jin³

et al. 2008

Drug Metab Dispos

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, 1997), which is an important traditional Chinese medicine used for the treatment of kidney deficiency and neurodegenerative diseases. ECH is also the main phenolic component in Echinacea angustifolia and Echinacea pallida roots (Perry et al., 2001), which are widely used in Europe, North America, and Australia for their immunostimulating activities. As a natural polyphenolic compound, ECH showed various bioactivities, such as antioxidative (Li et al., 1992;Xiong et al., 1996;Hu and Kitts, 2000;Cervellati et al., 2002), neuroprotective (Den et al., 2004;Koo et al., 2005;Chen et al., 2007;Geng et al., 2007), nitric oxide radical-scavenging (Xiong et al., 2000), and antihepatotoxic activities (Houghton and Hikino, 1989;Wu et al., 2007).Although ECH exhibited diverse bioactivities in in vivo and in vitro assays, only a few reports dealing with the metabolism and disposition of ECH are available. In our previous study on the pharmacokinetics and bioavailability of ECH in rat, the distribution and elimination of ECH were extremely fast (t 1/2␣ , 12.4 min; t 1/2␤ , 41.0 min), clearance was 0.0001 mg/kg/min/(ng/ml) after i.v. administration (5 mg/kg), and the bioavailability of ECH was only 0.83% (Jia et al., 2006). The very low bioavailability of ECH was consistent with the results of Matthias et al. (2004), in which ECH permeated poorly through the Caco-2 monolayers. Moreover, our pharmacokinetic data suggested that ECH was mostly metabolized after dosing. Therefore, we hypothesized that, in addition to the parent compound, some metabolic products of ECH may show biological activities, thereby contributing to the pharmacological efficacy of ECH in vivo. It was necessary to

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Structural Elucidation of Hydroxylated Metabolites of the Isoflavan Equol by Gas Chromatography-Mass Spectrometry and High-Performance Liquid Chromatography-Mass Spectrometry

Cited by 50 publications

References 27 publications

Conversion of Daidzein and Genistein by an Anaerobic Bacterium Newly Isolated from the Mouse Intestine

Conversion of Daidzein and Genistein by an Anaerobic Bacterium Newly Isolated from the Mouse Intestine

The red clover isoflavone irilone is largely resistant to degradation by the human gut microbiota

Metabolism of Echinacoside, a Good Antioxidant, in Rats: Isolation and Identification of Its Biliary Metabolites

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