A Novel Monitoring Approach for Mammalian Lignan Precursors in Flaxseed

Abstract

The mammalian lignans enterolactone and enterodiol have gained reputation as cancer-protective agents. These substances are produced in man by a gut microfloral-promoted transformation of opportune plant lignan precursors such as secoisolariciresinol diglucoside (3). This lignan is largely contained in flaxseed in the form of a more complex glucoside of still undisclosed structure and thus unsuitable for direct quantitative procedures. Since flaxseed-supplemented diets are usually employed to investigate the cancer-protective effect of a high mammalian lignan producing diet, a rapid and reliable analytical method for assaying 3 yield in flaxseed would be highly desirable. Acid hydrolysis of defatted flaxseed gives rise to 3,4-bis[(3-methoxy-4-hydroxy-phenyl)methyl] tetrahydrofuran (5), a degradation product readily amenable to gas chromatography resulting from the quantitative secoisolariciresinol-carrying complex glucoside cleavage. A gas chromatography-based internal standard method was then set up to derive the true content of 3 from the quantitative determination of the hydrolysis product 5. The method can reliably quantitate 5 with good linearity, accuracy and precision.