Hydroxyl radical-scavenging property of secoisolariciresinol diglucoside (SDG) isolated from flax-seed

January 1, 1997 Human Health and Nutrition Data 0 Comments

Hydroxyl radical-scavenging property of secoisolariciresinol diglucoside (SDG) isolated from flax-seed

Year: 1997
Authors: Prasad, K.
Publication Name: Molecular and Cellular Biochemistry
Publication Details: Volume 168; Pages 117 – 123.

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)
Flaxseed contains secoisolariciresinol diglucoside (SDG) known as plant lignans. Flaxseed has been shown to have beneficial effects in breast cancer [8] and lupus nephritis in experimental animals and humans. Antioxidants have been shown to have beneficial effect against various types of cancer including breast cancer. The beneficial effect of flaxseed in these conditions could be due to antioxidant activity of the SDG. In this study, using high pressure liquid chromatography (HPLC), the ability of SDG to scavenge exogenously generated hydroxyl radical (OH) by ultraviolet (UV) light photolysis of H2O2 was explored. The ability of SDG to prevent OH-induced lipid peroxidation in biological system was also investigated. Photolysis of H2O2 by UV irradiation produces OH which hydroxylates salicylic acid to generate OH-adduct products 2,3-DHBA, 2,4-DHBA, 2,5-DHBA and 2,6-DHBA. SDG produced a concentration dependent reduction in the formation of 2,3-DHBA and 2,5-DHBA, the inhibition being 66.5% for 2,3-DHBA and 63% for 2,5-DHBA at a concentration of 1 mg/ml (1.456 mM). These data suggest that SDG is a scavenger of OH. OH produced a marked increase in the production of MDA in liver homogenate as expected. SDG produced a concentration-dependent decrease in the formation of MDA. The reduction in lipidperoxidation in liver homogenate by SDG is probably due to scavenging of OH. This is supported by the fact that SDG scavenged OH generated by UV-induced photolysis of H2O2 in the present study. It is also likely that SDG may react with many other radicals involved in peroxidation process and hence could reduce lipid peroxidation. In conclusion, these results suggest that SDG is a scavenger of OH and the effectiveness of flaxseed in some of the diseases like cancer could be due to its antioxidant activity.  (Editors comments)



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