Lignans Enterodiol

DMA) and equol, while for lignans enterodiol and enterolactone should be used. 

Recently, some of the specific faecal bacteria involved in the metabolism of dietary isoflavonoids were isolated (Hur et al., 2000). They have been shown to selectively convert genistin and daidzin to their respective aglycones. One of the isolated bacteria, under anoxic conditions, was further shown to metabolise genistein and daidzein to their respective dihydroxy-genistein and dihydroxy-daidzein. In the case of lignans, enterodiol and enterolactone were shown to be excreted in vivo only in rats harbouring a gut microflora (Rowland et al, 1999). 

Wang, L.Q., Meselhy, M.R., Li, Y., Qin, G.W., and Hattori, M., Human intestinal bacteria capable of transforming secoisolariciresinol diglucoside to mammalian lignans, enterodiol and enterolactone, Chem. Pharm. Bull, 48, 1606, 2000. 

The lignans enterodiol, enterolactone and NDGA and the lignan metabolite methyl p-hydroxyphenyllactate interfere with mitogenic and tumor promotional signal transduction pathways [153], NDGA and methyl p-hydroxyphenyllactate did not inhibit 12-G-tetradecanoylphorbol-13-acetate (TPA) mediated c-fos transcription, and enterolactone and enterodiol had only a weak inhibitory effect. NDGA at 0.1-10 p.mol/L increased c-fos mRNA levels. 

Flaxseed contains the compound secoisolariciresinol diglycoside (SDG), which is converted by bacteria in the colon to the mammalian lignans enterodiol and enterolactone, compounds that have phytoestrogenic activity (Power and Thompson 2007). 

Fig. 2.86. Chemical structures of the iosflavones daidzein, genistein, O-desmethylangolensin, equol, and the lignans enterolactone and enterodiol. Reprinted with permission from Z. Kuklenyik el al. [209].

Gut microflora metabolites may also be important. As discussed above, the mammalian lignan aglycones, enterodiol and enterolactone, are estrogenic, and equol is more estrogenic than its dietary precursor, the isoflavone daidzein. ... 

Jacobs, E., Kulling, S.E., and Metzler, M., Novel metabolites of the mammalian lignans enterolactone and enterodiol in human urine, J. Steroid Biochem. Mol Biol, 68, 211, 1999. 

Heinonen, S., Nurmi, T., Liukkonen, K., Poutanen, K., Wahala, K., Deyama, T., Nishibe, S., and Adlercreutz, H., In vitro metabolism of plant lignans new precursors of mammalian lignans enterolactone and enterodiol, J. Agric. Food Chem., 49, 3178, 2001. 

Adlercreutz H, Fotsis T, Heikkinen R, Dwyer JT, Woods M, Goldin BR, Gorbach SL. 1982. Excretion of the lignans enterolactone and enterodiol and of equol in omnivorous and vegetarian postmenopausal women and in women with breast cancer. Lancet 2 1295-1299. 

The presence of the oxidized metabolites is unique and may provide additional reasons for the health benefits of lignans. Classical antioxidant mechanisms show that the addition of an ortho hydroxyl group to a monophenol enhances the antioxidant activity of the original monophenol. Thus, some of the mammalian lignan metabolites may actually have greater or different activity than the parent lignan. Kitts et al (1999) reported that enterolactone and enterodiol had greater antioxidant activity than the parent... 

Kitts, D.D., Yuan, Y.V., Wijewickreme, A.N., and Thompson, L.U. 1999. Antioxidant activity of the flaxseed lignan secoisolariciresinol diglycoside and its mammalian lignan metabolites enterodiol... 

Power, K.A., Saarinen, N.M., Chen, J., and Thompson, L.U. 2004. Lignans (enterolactone and enterodiol) negate the proliferative effect of sioflavone (genistein) on MCF-7 breast cancer cells in vitro and in vivo (abstract). Proc. AACR 45, 878. 

Enterodiol] (lignan) Mammalian lignan derived from intestinal bacterial modification of lignans from ingested Secale cereale (rye) (Poaceae) AROM... 

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