Exploring the Health Benefits of Flaxseed: Extraction and Enrichment of Secoisolariciresinol Diglucoside and its Polymer

Abstract: Plant lignans are a class of natural plant diphenolic compounds that are made by the condensation of two phenylpropanoid moieties. Oilseed and cereal crops, including flaxseed and sesame seed, are major sources of plant lignan, with flaxseed containing the highest amount of lignan among all plants tested. Secoisolariciresinol diglucoside (SDG), a compound that can elicit responses in mammals that mimic estrogen, is the primary lignan produced in flaxseed. The lignan SDG can be metabolized into enterodiol and enterolactone by intestinal bacteria. These molecules can then be absorbed and further affect mammalian physiology. SDG, from flaxseed, is in the form of a heteropolymer that contains SDG crosslinked with 3-hydroxy-3-methylglutaric acid by ester bonds. The objective of this study was to establish a method for recovering SDG polymer and SDG with acceptable yield and quality. Two experimental methods were developed to extract SDG polymer from defatted whole flaxseed meal using aqueous ethanol and subsequent ammonia hydroxide hydrolysis to release the SDG molecule from its copolymer. The SDG product was then refined over resin. Yields of SDG polymer and SDG were 2.7% (of defatted meal mass) and 51.9% (of isolated SDG polymer mass), respectively. The content of SDG in the polymer and SDG were 65.8 g SDG/g polymer and 89.5 g SDG/g, respectively. These results indicate a possible industrial process for the recovery of flaxseed lignan from defatted flaxseed meal. This approach can reduce total production costs and further reduce the price of enriched flaxseed lignan, providing accessibility and benefits for its use in medicine and as a dietary supplement or another health ingredient.