Time-resolved fluoroimmunoassay for plasma enterolactone

Anal Biochem. 1998 Dec 15;265(2):208-15. doi: 10.1006/abio.1998.2886.


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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 4-Butyrolactone / analogs & derivatives*
  • 4-Butyrolactone / blood
  • Fluoroimmunoassay / methods*
  • Gas Chromatography-Mass Spectrometry
  • Humans
  • Lignans / blood*
  • Sensitivity and Specificity


  • Lignans
  • 4-Butyrolactone
  • 2,3-bis(3'-hydroxybenzyl)butyrolactone