Monoclonal antibody-based time-resolved fluorescence immunoassays for daidzein, genistein and equol in blood and urine: application to the Isoheart Intervention Study

Research output: Contribution to journalJournal articleResearchpeer-review

  • Duncan C.S. Talbot
  • Richard M. Ogborne
  • Tony Dadd
  • Herman Adlercreutz
  • Geoff Barnard
  • Bügel, Susanne Gjedsted
  • Fortune Kohen
  • Sandra Marlin
  • Jerry Piron
  • Aedin Cassidy
  • Jonathan Powell

Background: Time-resolved fluorescence immunoessays (TR-FIAs) for phytoestrogens in biological samples are an alternative to mass spectrometric methods. These immunoessays were used to test urne and plasma samples from individuals in a dietary trial aimed at determining the efficacy of dietary isoflavones in reducing the risk of coronary heart disease in postmenopaususal women.

Methods: We estalished murine monoclonal TR-FIA methods for daidzein, genistein and equol. The assays could be perfomed manually or adapted to an automated analyzer for the high throughput and increased accuracy. Analysis of urine was conducted on nonextracted samples. Blood analysis was performed on nonextracted samples for daidzein, whereas genestein and equol erquired diethyl-ether extraction.

Results: Comparison of monoclonal TR-FIA, commercial polyclonal antibody-based TR-FIA and gas chromatography-mass spectrometry showed correlations (r, 0.911-0,994) across the concentration range observed in the Isoheart sudy (50 mg/day isoflavones). The concentartions of urinary daidzein and genistein observed during intervention demonstrated good compliance and a corresponding incrase in serum daidzein and genestein confirmed bioavailability of the isoflavone-rich foods; 33 of th 117 volunteers (28,2%) were classified as equol producers on the absis of their urinary equol concentration (>936 nmol/L),and significant differences in the numbers of equol producers were observed between Berling and the 3 other European cohorts studied.

Conclusions: The validated monoclonal TR-FIA methods are applicable for use in large-scale human phytoestrogen intervention studies and can be used to monitor cokpliance, demonstrate bioavailability and assess equol producer status.

Original languageEnglish
JournalClinical Chemistry
Issue number4
Pages (from-to)748-756
Number of pages9
Publication statusPublished - 2007

ID: 8064263