Lignans sources

Toure A, Xueming X. Flaxseed lignans source, biosynthesis, metabolism, antioxidant activity, bio-active components, and health benefits. Compr Rev Food Sci Food Saf. 2010 9 261-269. 

Toure, A. and Xueming, X. Flaxseed Lignans Source, Biosynthesis, Metabolism, Antioxidant Activity, Bio-Active Components, and Health Benefits. Comprehensive Reviews in Food Science and Food Safety 9, (3), 261-269. 

The three main classes of phytoestrogens (and common food sources) are isoflavones (soybeans), lignans (cereals and oilseeds such as flaxseed), and coumestans (alfalfa sprouts). The biologic potency of phytoestrogens varies and is less than that of synthetic estrogen. 

Hypocholesterolemic activity. Extract of the dried entire plant, administered to rats at a dose of 30% of diet, was active " . Lignan fraction of the seed, administered in the ration of 4-week-old rats at a dose of 0.2% of the diet for 3 weeks, was active. Dietary fat sources were safflower and primrose oils . 

The plant precursors of mammalian lignans include secoisolaricinol, laricresinol, matair-esinol, 7-hydroxymatairesinol, pinoresinol, and lignin. ° ° Flaxseed and whole cereal grains are considered the most important dietary sources, but many others are known, for example, strawberry achenes, berries, coffee beans, tea leaves, etc. ... 

The morama bean is an excellent source of lignans (Holse et al., 2010). The content of secoisolariciresinol in morama beans (305-406 gg/100 g) is higher than that of soybean (13-273 gg/100 g) and peanut (333 pg/100 g) (Mazur et al., 1998). Likewise, the level of lariciresinol in morama beans (614-825 [tg/100 g) is higher than that of soybeans (287 gg/lOO g), while the level of pinoresinol in morama beans (21-23 gg/lOO g) is lower than the level in soybeans (446 gg/lOO g) (Penalvo et ah, 2004). These lignans can be converted by intestinal bacteria into enterolignans, which possess biological activities such as (anti) estrogenic and antioxidant action. Therefore, they may reduce the risk of certain types of cancers as well as cardiovascular diseases (Adlercreutz, 2007). 

Ullmann reaction (4, 33-34). Semmelhack et al.1 recorded details of the coupling of aryl and vinyl halides with Ni(0) complexes, (COD)2Ni or Ni[P(C6H5)3]4. This reaction was used for the first synthesis of almusone (3), an antileukemic lignan obtained from the wood of Alnus japonica Steud. In the case of ort/io-substituted aryl iodides such as 1, reduction becomes a competing reaction and the yields are only moderate. In fact o,o-disubstituted aryl halides cannot be coupled under these conditions. Deliberate addition of a proton source increases formation of the reduction product. Acetic or trifluoroacetic acid are useful for this purpose. Added triphenyl-phosphine also promotes reduction. 

Flaxseed is an oilseed that contains roughly 38 15% oil. ALA, a polyunsaturated lipid, accounts for 52% of the fatty acids in the oil. Flaxseed is also a rich source of plant lignans (up to 13 mg g flaxseed). The interest in ALA and... 

Flaxseed was among the best food sources in the prevention of in vivo spontaneous chromosomal damage in mice (Trentin et al., 2004). The exact reason for the chromosomal damage prevention was not identified however, the mechanism may be related to the antioxidant function of flaxseed components. Lignans have antioxidant activity and thus may contribute to the anticancer activity of flaxseed (Kangas et al., 2002 Kitts et al., 1999 Prasad 1997a, Yuan et al., 1999). 

Axelson, M. and Setchell, K.D.R. 1981. The excretion of lignans in rats as evidence for an intestinal bacterial source for this new group of compounds. FEES Lett. 123, 337-343. 

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