title: Quantification of isoflavones and lignans in serum using isotope dilution liquid chromatography/tandem mass spectrometry.
abstract: Phytoestrogens (isoflavones and lignans) are receiving increasing attention due to a potential protective effect against a number of complex diseases. However, in order to investigate these associations, it is necessary to accurately quantify the levels of phytoestrogens in foods and biological fluids. We report an assay for three isoflavones (daidzein, genistein, and glycitein), two metabolites of daidzein (O-desmethylangolensin and equol), and two lignans (enterodiol and enterolactone) in human serum using electrospray ionisation liquid chromatography/mass spectrometry (LC/MS) with selective reaction monitoring. A simple, highly automated sample preparation procedure requires only 200 microL of sample and utilises one solid-phase extraction stage. Limits of detection are in the region of 10 pg/mL for all analytes except equol, which had a limit of detection of approximately 100 pg/mL. The method developed is suitable for measuring the concentrations of phytoestrogens in blood samples collected from large epidemiological studies. The results of the analysis of serum samples from 300 men and women living in the UK are reported.
authors.affiliation: MRC Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, UK.
authors.forename: Philip B
authors.initials: PB
authors.lastname: Grace
authors.affiliation: MRC Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, UK.
authors.forename: James I
authors.initials: JI
authors.lastname: Taylor
authors.affiliation: School of Chemistry, University of St. Andrews, St. Andrews KY16 9ST, UK.
authors.forename: Nigel P
authors.initials: NP
authors.lastname: Botting
authors.affiliation: School of Chemistry, University of St. Andrews, St. Andrews KY16 9ST, UK.
authors.forename: Tara
authors.initials: T
authors.lastname: Fryatt
authors.affiliation: School of Chemistry, University of St. Andrews, St. Andrews KY16 9ST, UK.
authors.forename: Mark F
authors.initials: MF
authors.lastname: Oldfield
authors.affiliation: School of Chemistry, University of St. Andrews, St. Andrews KY16 9ST, UK.
authors.forename: Nawaf
authors.initials: N
authors.lastname: Al-Maharik
authors.affiliation: MRC Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, UK.
authors.forename: Sheila A
authors.initials: SA
authors.lastname: Bingham
mesh_terms: D002138:Calibration; D002853:Chromatography, Liquid; D004968:Estrogens, Non-Steroidal / Q000097:blood; D005260:Female; D006801:Humans; D007529:Isoflavones / Q000097:blood*; D007554:Isotopes; D017705:Lignans / Q000097:blood*; D008297:Male; D013058:Mass Spectrometry; D048789:Phytoestrogens; D028321:Plant Preparations; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D006113:United Kingdom
chemical_list: D004968:Estrogens, Non-Steroidal; D007529:Isoflavones; D007554:Isotopes; D017705:Lignans; D048789:Phytoestrogens; D028321:Plant Preparations