Lignans in flaxseed

The main lignan in flaxseed is SDG (Figure 2). Also present are a number of other lignans, that is, matairesinol (MAT), lariciresinol, hinokinin,... 

Popova IE, Hall C, Kubatova A (2009) Determination of lignans in flaxseed using liquid chromatography with time-of-flight mass spectrometry. J Chromatogr A 1216 ... 

At least six different methods have been proposed for the analysis of lignans in flaxseed and products containing flaxseed, and three different methods for analysis of lignan metabolites in mammalian tissues and fluids since the lignan SDG was first isolated from flax by Bakke and Klosterman (1956). In addition, several variafions exist for many of these methods. Variations in extraction of lignans from flaxseed and products containing flaxseed further complicate its analysis. Results from these studies have been inconsistent mainly because of differences in methodology. 

A new standard method for analysis of lignans in flaxseed and products containing flaxseed has been proposed (Muir et al., 2000) and is outlined in Figure 1.12. Extraction is carried out with aqueous alcohol, either ethanol or methanol, with a liquid-to-solid ratio of 20 1. The isolated ester complex is hydrolyzed with dilute base for 3 h at room temperature, neutralized (0.5 mL 0.5 N HAC), filtered, concentrated if necessary, and subjected to HPLC analysis. Quantitation is achieved by using SDG as external standard. When higher sensitivity is required, samples can be analyzed by LC-MS using soft ionization techniques such as ESI or APCl. Results are expressed as mg SDG/g samples or preferably in pmol/g of sample. 

Oomah, B.D., Processing of flaxseed fiber, oil, protein, and lignan, in Flaxseed in Human Nutrition, 2nd edition, Thompson, L.U. and Cunnane, S.C. (Eds), AOCS Press, Champaign, IL, 363-386, 2003. 

Thompson, L.U., Rickard, S.E., Cheung, F. et al., Variability in anticancer lignan levels in flaxseed, Nutr. 

Madhusudhan, B., Wiesenbom, D., Schwarz, J., Tostenson, K., and Gillespie, J. 2000. A dry mechanical method for concentrating the lignan secoisolariciresinol diglucoside in flaxseed. Leb. Wiss. Tech. 33, 268-275. 

Rickard, S.E., Orcheson, L.J., and Seidl, M.M. 1996. Dose-dependent production of mammalian lignans in rats and in vitro from the purified precursor secoisolariciresinol diglycoside in flaxseed. 

Saarinen, N.M., Makela, S., and Satti, R. 2003. Mechanism of anticancer effects of lignans with a special emphasis on breast cancer. In Flaxseed in Human Nutrition (S.C. Cunnane and L.U. Thompson, eds), 2nd Ed., pp. 223-228. AOCS Press, Champaign, IL. 

Ward, W.E., Yuan, Y.V., Cheung, A.M., and Thompson, L.U. 2001b. Exposure to purified lignan from flaxseed (Linum usitatissimum) alters bone development in female rats. Br. J. Nutr. 86, 499-505. 

Lignans of flaxseed exist as secoisolariciresinol diglucoside (SDG 126). SDG is a potent antioxidant in biological systems because of its tendency to associate in the aqueous phase. Much of the work on antioxidant activity of SDG is related to its radical mediated disease prevention (127, 128). Lignans of both sesame (121, 122) and flax (129, 130) have shown hydrogen-donating abihty and scavenging activity for various free radicals. 

Lignans from flaxseed have been shown to reduce mammary tumor size by more than 50% and tumor number by 37% in carcinogen-treated rats (19, 20). Eurther-more, it has been suggested that lignans have antimiotic, antiestrogenic, antiviral, antibacterial, antifungal, and antioxidant properties (20-33). 

The presence of plant lignans in flax oil makes it nutritionally more valuable than any other oil. When high levels of ALA and hnoleic acid are considered in the whole equation, flaxseed oil serves as the best oil in terms of its nutritional and health value. 

Nesbitt, RD. and L.U. Thompson. 1997. Lignans in homemade and commercial products containing flaxseed. Nutr. Cancer 29 222-227. 

Coran, S.A., Giannellini, V., and Bambagiotti-Alberti, M., A novel monitoring approach for mammalian lignan precursors in flaxseed, Pharm. Sci., 2, 529,1996. 

Pietrofesa R, Turowski J, Tyagi S, et al. Radiation mitigating properties of the lignan component in flaxseed. BMC Cancer. 2013 13 179. 

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