Key Findings:
Numerous positive effects of flaxseed lignans have been reported for cardiovascular disease, inflammation and cancer which may be due to antioxidant activity of SDG. In this study, using high pressure liquid chromatography (HPLC), it was found that SDG produced a concentration dependent reduction in the formation of pro-oxidants. SDG scavenged hydroxyl radical (•OH) generated by UV-induced photolysis of H2O2. SDG may react with many other radicals involved in peroxidation process and could reduce lipid peroxidation.
ABSTRACT:
Recently there has been a moderate resurgence in the use of flax-seed in a variety of ways including bread. The scientific basis of its use is very limited. There is some claim for beneficial effects in cancer and lupus nephritis. These claims could be due to its ability to scavenge oxygen radicals. However, its antioxidant activity is not known. Recently a method has been developed to isolate secoisolariciresinol diglucoside (SDG) from defatted flax-seed in large quantity (patent pending). We investigated the ability of SDG to scavenge •OH using high pressure liquid chromatography (HPLC) method. •OH was generated by photolysis of H2O2 (1.25–10.0 μmoles/ml) with ultraviolet light and was trapped with salicylic acid which is hydroxylated to produce •OH-adduct products 2,3-dihydroxybenzoic acid (DHBA) and 2,5-DHBA. H2O2 produced a concentration-dependent •OH as estimated by 2,3-DHBA and 2,5-DHBA. A standard curve was constructed for known concentrations of 2,3-DHBA and 2,5-DHBA against corresponding area under the peaks which then was used for measurement of 2,3-DHBA and 2,5-DHBA generated by UV irradiation of H2O2 in the presence of salicylic acid. SDG in the concentration range of 25, 50, 100, 250, 500, 750, 1000 and 2000 μg/ml (36.4, 72.8, 145.6, 364.0, 728.0, 1092.0, 1456.0 and 2912.0 μM respectively) produced a concentration- dependent decrease in the formation of 2,3-DHBA and 2,5-DHBA, the inhibition being 4 and 4.65% respectively with 25 μg/ml (36.4 μM) and 82 and 74% respectively with 2000 μg/ml (2912.0 μM). The decrease in •OH-adduct products was due to scavenging of •OH and not by scavenging of formed 2,3-DHBA and 2,5-DHBA. SDG prevented the lipid peroxidation of liver homogenate in a concentration-dependent manner in the concentration range from 319.3–2554.4 μM. These results suggest that SDG scavenges •OH and therefore has an antioxidant activity. (Authors abstract)
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