title: Detection of novel metabolites of flaxseed lignans in vitro and in vivo.
abstract: This study aimed to improve the knowledge of secoisolariciresinol diglucoside (SDG) transformation by human gut microbiota.
  
  
  
  SDG-supplemented microbiota cultures were inoculated with the feces of five subjects. The same volunteers received a flaxseed supplement for 7 days. SDG metabolites in cultures, feces, and urine were monitored by LC-ESI-QTOF and LC-DAD. In all cultures, SDG was deglycosylated to secoisolariciresinol (SECO) within 12 h. SECO underwent successive dehydroxylations and demethylations yielding enterodiol (4-18% conversion) and enterolactone (0.2-6%) after 24 h. Novel intermediates related to SECO, matairesinol (MATA), and anhydrosecoisolariciresinol (AHS) were identified in fecal cultures. These metabolites were also found after flaxseed consumption in feces and urine (in approximate amounts between 0.01-47.03 μg/g and 0.01-13.49 μg/mL, respectively) in their native form and/or modified by phase II human enzymes (glucuronide, sulfate and sulfoglucuronide conjugates).
  
  
  
  Derivatives of MATA and AHS are described for the first time as intermediates of SDG biotransformation by intestinal bacteria, providing a more comprehensive knowledge of lignan intestinal metabolism. The transformations observed in vitro seem to occur in vivo as well. The detection in urine of SDG intermediates indicates their gut absorption, opening new perspectives on the study of their systemic biological effects.
authors.affiliation: Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Quartieri
authors.affiliation: Department of Food Science and Technology, CEBAS-CSIC, Murcia, Spain.
authors.forename: Rocío
authors.initials: R
authors.lastname: García-Villalba
authors.affiliation: Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Amaretti
authors.affiliation: Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Raimondi
authors.affiliation: Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Alan
authors.initials: A
authors.lastname: Leonardi
authors.affiliation: Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Maddalena
authors.initials: M
authors.lastname: Rossi
authors.affiliation: Department of Food Science and Technology, CEBAS-CSIC, Murcia, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Tomàs-Barberàn
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives / Q000737:chemistry / Q000652:urine; D000328:Adult; D000070257:Bifidobacterium pseudocatenulatum; D002072:Butylene Glycols / Q000737:chemistry / Q000652:urine; D019587:Dietary Supplements; D005243:Feces / Q000737:chemistry / Q000382:microbiology; D005260:Female; D019597:Flax / Q000737:chemistry*; D005663:Furans / Q000737:chemistry / Q000652:urine; D000069196:Gastrointestinal Microbiome; D005960:Glucosides / Q000737:chemistry / Q000652:urine; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000382:microbiology; D017705:Lignans / Q000008:administration & dosage* / Q000737:chemistry* / Q000652:urine; D008297:Male; D008875:Middle Aged; D056692:Prebiotics / Q000008:administration & dosage; D019936:Probiotics / Q000008:administration & dosage; D055815:Young Adult
chemical_list: D002072:Butylene Glycols; D005663:Furans; D005960:Glucosides; D017705:Lignans; D056692:Prebiotics; C068935:matairesinol; C029498:2,3-bis(3'-hydroxybenzyl)butane-1,4-diol; C060283:secoisolariciresinol; D015107:4-Butyrolactone; C090142:secoisolariciresinol diglucoside; C029497:2,3-bis(3'-hydroxybenzyl)butyrolactone
keywords: Enterolactone; Flaxseed; Human gut microbiota; Lignan metabolites; Pilot study