Antioxidant capacity of flaxseed lignans in two model systems

The flaxseed lignans secoisolariciresinol (SECO) and its diglucoside secoisolariciresinol diglucoside (SDG) are reported to have a number of health benefits associated with their consumption that have in part been attributed to their antioxidant properties. In this study the relative antioxidant capacity of the flaxseed lignans vs. BHT was determined in two model systems. First, an antioxidant stoichiometric value was determined for SECO and SDG in a liposomal system as a mimic of lipid peroxidation. Stoichiometric values for SECO (1.5) and SDG (1.2) vs. BHT (2.0) were measured from the lag time for the formation of conjugated dienes; all values were significantly different (P < 0.01). Second, the ability of flaxseed lignans to prevent oxidative degradation of canola oil was determined. Samples were stored at room temperature and analyzed at 30-d intervals over 120 d using a Rancimat (TM) analyzer. The lignans prevented degradation of canola oil, as measured by induction time, in a concentration-dependent manner. Although SECO demonstrated a trend for better protection than either SDG or polymer containing SDG, they were not significantly different (P > 0.01). There was also no significant difference between SECO or SDG and BHT, suggesting flaxseed lignans may be good alternatives to minimize rancidity in oil-based food products.