title: Time-resolved fluoroimmunoassay for plasma enterolactone.
abstract: We present a method for the determination of the lignan enterolactone in plasma (serum). This compound, produced by intestinal bacteria from matairesinol and secoisolariciresinol in fiber-rich food, is a biomarker related to the intake of a healthy diet. The method is based on time-resolved fluoroimmunoassay using a europium chelate as a label. After synthesis of 5'-O-carboxymethoxyenterolactone the compound is coupled to bovine serum albumin and then used as antigen in immunization of rabbits. The tracer with the europium chelate is synthesized using the same 5'-derivative of enterolactone. After enzymatic hydrolysis and ether extraction the immunoassay is carried out using the VICTOR 1420 multilabel counter (Wallac Oy, Turku, Finland). No antiserum cross-reactivity with available lignans, isoflavonoids, or flavonoids could be detected. The intraassay and interassay coefficients of variation at different concentrations vary 4.6-6.0 and 5.5-9.9, respectively. The working range of the assay is 1.5-540 nmol/liter. We measured enterolactone in serum/plasma of 224 Finnish subjects: 98.8% of the subjects had values <100 nmol/liter, 38.0% had 20-39.9 nmol/liter, and 34.4% had <20 nmol/liter.
authors.affiliation: Institute for Preventive Medicine, Nutrition and Cancer, Helsinki, Finland.
authors.forename: H
authors.initials: H
authors.lastname: Adlercreutz
authors.forename: G J
authors.initials: GJ
authors.lastname: Wang
authors.forename: O
authors.initials: O
authors.lastname: Lapcík
authors.forename: R
authors.initials: R
authors.lastname: Hampl
authors.forename: K
authors.initials: K
authors.lastname: Wähälä
authors.forename: T
authors.initials: T
authors.lastname: Mäkelä
authors.forename: K
authors.initials: K
authors.lastname: Lusa
authors.forename: M
authors.initials: M
authors.lastname: Talme
authors.forename: H
authors.initials: H
authors.lastname: Mikola
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000097:blood; D015200:Fluoroimmunoassay / Q000379:methods*; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D017705:Lignans / Q000097:blood*; D012680:Sensitivity and Specificity
chemical_list: D017705:Lignans; D015107:4-Butyrolactone; C029497:2,3-bis(3'-hydroxybenzyl)butyrolactone