Optimization of a liquid chromatography-tandem mass spectrometry method for quantification of the plant lignans secoisolariciresinol, matairesinol, lariciresinol, and pinoresinol in foods

Abstract

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the quantification of the four major enterolignan precursors [secoisoladciresinol, matairesinol, lariciresinol, and pinoresinol] in foods. The method consists of alkaline methanolic extraction, followed by enzymatic hydrolysis using Helixpomatia pomatia (H. pomatia) β-glucuronidase/ sulfatase. H. pomatia was selected from several enzymes based on its ability to hydrolyze isolated lignan glucosides. After ether extraction samples were analyzed and quantified against secoisolariciresinol-d8 and matairesinol-d6. The method was optimized using model products: broccoli, bread, flaxseed, and tea. The yield of methanolic extraction increased up to 81%, when it was combined with alkaline hydrolysis. Detection limits were 4-10 μg/(100 g dry weight) for solid foods and 0.2-0.4 μg/(100 mL) for beverages. Within- and between-run coefficients of variation were 6-21 and 6-33%, respectively. Recovery of lignans added to model products was satisfactory (73-123%), except for matairesinol added to bread (51-55%).