Structural Modifications of a Flaxseed Lignan in Pursuit of Higher Liposolubility: Evaluation of the Antioxidant and Permeability Properties of the Resulting Derivatives

While lignans and their biogenetic precursors can have various health benefits, the poor liposolubilities of such phenolic systems have restricted their application as antioxidants in the food industry. The research reported here was aimed at addressing these matters through derivatizing certain forms of such compounds and then assessing their properties as potential nutraceuticals. In particular, crude flaxseed lignan was purified to afford secoisolariciresinol diglucoside (SDG, 1) that was then subjected to structural modification. By such means, the SDG long-chain fatty acid esters 4-9 and 11-13, the fully acetylated SDG 10, secoisolariciresinol (SECO, 2), and anhydrosecoisolariciresinol (ASECO, 14) were obtained. The antioxidant activities of these derivatives were determined while their permeability properties were evaluated. Such studies revealed that certain SDG derivatives possessing useful liposolubilities also retained their antioxidative properties, as well as being capable of permeating Caco-2 cell monolayers while being nontoxic to them. SDG fatty acid esters 4-9 and 11-13 could be developed into emulsifiers with enhanced health benefits, especially considering their improved antioxidative (ca. <11 »000 μmol Trolox/g) and permeability properties. This study thus highlights strategies for the structural modification of SDG so as to generate derivatives with superior properties in terms of their utility in the food and pharmaceutical industries.