Flaxseed Ingestion Alters Ratio of Enterolactone Enantiomers in Human Serum

Niina M Saarinen,Sari Mäkelä,Herman Adlercreutz,José L Peñalvo,Tarja Nurmi,Annika I Smeds

doi:10.1155/2010/403076

Abstract

Enterolactone (EL) is an enterolignan found in human subjects. In this pilot study, the enantiomeric ratios of serum EL were determined in serum from healthy adults during consumption of habitual diet, and after an 8-day supplementation with flaxseed (25 g/day). (−)EL dominated in all serum samples collected during habitual diet consumption. However, the ratio of (−)EL and (+)EL enantiomers differed markedly between individuals. Flaxseed ingestion increased significantly the proportion of (+)EL in all subjects. Moreover, a small but significant increase in serum (−)EL concentration was measured. After flaxseed ingestion, (−)EL concentrations correlated with those of (+)EL suggesting that the stereochemistry of the parent plant lignan in flaxseed is not a major determinant of EL formation in human subjects. Comparison of EL concentrations obtained with the validated chromatographic methods (HPLC-MS/MS, HPLC-CEAD, and GC-MS) and the time-resolved fluoroimmunoassay (TR-FIA) revealed that the immunoassay method underestimates human serum EL concentrations after the flaxseed ingestion.

Highlights

Enterolactone (EL) is an enterolignan produced by intestinal microbiota from several dietary plant lignans [1]
The enantiomeric ratios of serum EL were determined in serum from healthy adults during consumption of habitual diet, and after an 8-day supplementation with flaxseed (25 g/day). (−)EL dominated in all serum samples collected during habitual diet consumption
Comparison of EL concentrations obtained with the validated chromatographic methods (HPLC-MS/MS, HPLC-CEAD, and GC-MS) and the time-resolved fluoroimmunoassay (TR-FIA) revealed that the immunoassay method underestimates human serum EL concentrations after the flaxseed ingestion

Summary

Introduction

Enterolactone (EL) is an enterolignan produced by intestinal microbiota from several dietary plant lignans [1]. EL is a chiral compound, and the enantiomers occurring as plant lignan metabolites are (8R, 8 R)-(−)EL and (8S, 8 S)-(+)EL (Figure 1). Our previous studies in rats have demonstrated that the absolute configuration at C8 and C8 of the parent plant lignan is not changed during the intestinal metabolism to EL [7]. (−) enantiomers of formed EL is determined by the stereochemistry of the plant lignan precursors. Whether the stereochemistry determines metabolic conversion capability of plant lignans to enterolignans is not yet known

Methods

Results

Conclusion