title: Orally administered isoflavones are present as glucuronides in the human prostate.
abstract: Better knowledge of the bioavailability and metabolism of isoflavones in prostate tissue is needed to further investigate their mechanisms of action in the context of prostate cancer prevention. A total of 12 men with benign prostatic hyperplasia received soy extract supplementation (3 Evestrel capsules, providing a total of 112.5 mg isoflavones aglycone eq/day) for 3 days before prostate surgery. Blood and prostate tissues were sampled and metabolites were identified using electrospray ionization liquid chromatography tandem mass spectrometry (LC-ESI-MS/MS) and chemically synthesized standards of glucuronidated isoflavones. The main metabolites were the same in prostate tissue and in plasma, namely, 2 monoglucuronides of daidzein and 2 monoglucuronides of genistein. Concentrations of total isoflavones measured in prostate reached 1.05 +/- 0.62 nmol/g tissue (range 0.30-2.23) at the time of sampling, 12 h after the last isoflavone supplementation. At that time point, prostate concentrations were lower than plasma concentrations in all volunteers: 0.47 nmol/g vs. 0.66 microM for daidzein and 0.58 nmol/g vs. 0.78 microM for genistein. Isoflavone mechanisms of action should thus be investigated in in vitro cell studies using physiological conditions, intracellular concentrations below 5 nmol/g and no intracellular deconjugation of the monoglucuronide metabolites.
authors.affiliation: CHU Clermont-Ferrand, Service Urologie, Clermont-Ferrand, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Guy
authors.forename: Nicolas
authors.initials: N
authors.lastname: Védrine
authors.forename: Mireia
authors.initials: M
authors.lastname: Urpi-Sarda
authors.forename: Angel
authors.initials: A
authors.lastname: Gil-Izquierdo
authors.forename: Nawaf
authors.initials: N
authors.lastname: Al-Maharik
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Boiteux
authors.forename: Augustin
authors.initials: A
authors.lastname: Scalbert
authors.forename: Christian
authors.initials: C
authors.lastname: Remesy
authors.forename: Nigel P
authors.initials: NP
authors.lastname: Botting
authors.forename: Claudine
authors.initials: C
authors.lastname: Manach
mesh_terms: D000368:Aged; D002851:Chromatography, High Pressure Liquid; D004032:Diet; D019587:Dietary Supplements; D019833:Genistein / Q000032:analysis / Q000097:blood; D020719:Glucuronides / Q000032:analysis* / Q000378:metabolism*; D006801:Humans; D007529:Isoflavones / Q000008:administration & dosage* / Q000032:analysis / Q000097:blood / Q000493:pharmacokinetics*; D008297:Male; D008875:Middle Aged; D011467:Prostate / Q000737:chemistry*; D011470:Prostatic Hyperplasia / Q000378:metabolism / Q000601:surgery; D011471:Prostatic Neoplasms / Q000517:prevention & control; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry
chemical_list: D020719:Glucuronides; D007529:Isoflavones; C004742:daidzein; D019833:Genistein