An HPLC procedure for the quantification of anhydrosecoisolariciresinol. Application to the evaluation of flax lignan content

Plant lignans are natural products resulting from the phenylpropanoid metabolic pathway. Some of these compounds have phytoestrogen properties and may protect humans against hormone-dependent cancers such as breast cancer. Secoisolariciresinol, usually in glycosidic form, is the major lignan in flaxseed (Linum usitatissimum L.), and the main precursor of the mammalian lignans (enterodiol, enterolactone) known for their beneficial effects on human health. The quantification of secoisolariciresinol requires a preliminary acid hydrolysis, necessary for the release of lignans from their complex form and aglycone from the glycosylated derivatives. This step partially converts secoisolariciresinol into its anhydrous form: anhydrosecoisolariciresinol. For this reason, we have developed an HPLC quantification method of secoisolariciresinol from flaxseed through its derived form obtained by a total acid hydrolysis. These conditions allow a simplification of the HPLC procedure and allow complete transformation of secoisolariciresinol into its anhydrous form. Using this method, the lignan level in L. usitatissimum seeds was determined to be about 6 mg g–1 DW. Furthermore, levels of anhydrosecoisolariciresinol were also determined in the different organs of the whole plant, in particular the leaves, stems, roots and fruits. Seeds and fruits accumulated the highest levels of lignans.