Phytoestrogen coumestrol

KULLING s E, ROSENBERG B, JACOBS E, METZLER M (1999) The phytoestrogens coumestrol and genistein induce structural and chromosomal aberrations in cultured human peripheral blood lympocytes. Arch Toxicol. Ti 50-54. 

PATISAUL H B, WHITTEN p L, YOUNG L J (1999) Regulation of oestrogen receptor beta mRNA in the brain opposite effects of 17beta-oestradiol and the phytoestrogen, coumestrol. Brain Res Mol Brain Res. 67 165-71. 

Reinli and Block (1996) developed a compendium of literature values with 36 references for phytoestrogens (coumestrol, daidzein, genistein, biochanin A and formononetin) in foods. They also reported the relative potency of these phytoestrogen and equol (metabolites found in urine) in vitro and in vivo. Similar to the USDA-ISU database, this database reported total daidzein and genistein, which were estimated by the hydrolysis method or by normalizing the molecular weight differences of... 

The phytoestrogens (isoflavones) contain a flavone nucleus. Examples of isoflavones are genistein, formononetin and coumestrol, all with potent estrogenic activity. Soybean isoflavones are a concern in human nutrition because of their estrogenic benefits. 

In 1987, Ken Setchell first described the method for the isolation of phytoestrogen in soy (Setchell et al., 1987). The phytoestrogens daidzein, genistein, coumestrol, formononetin, and biochanin-A were separated on a Cl8 reversed-phase column (Hypersil ODS) with methanol-0.1 M ammonium acetate buffer, pH 4.6 (60 40 v/v), as eluent. The retention and resolution were affected by buffer concentrations, pH type, and proportion of organic solvent in the mobile phase. Detection in the low picograms range was achieved with an electrochemical detector, and the compounds were positively identified by HPLC-thermospray mass spectrometry. 

Over 300 different plants contain either compounds with estrogenic activity or precursors for the formation of nonsteroidal estrogens. Coumestrol, equol, and zearalenone are examples of phytoestrogens that are found in legumes, tubers, and fungi that infest grains. These substances clearly act as reproductive toxins in sheep (equol in clover disease) and... 

Jones et al. (1989) developed an HPLC-UV (262 nm) method (C18 column) for analysis of phytoestrogens and coumestrol. Ethyl benzoate was used as an internal standard. The recovery rate was from 90% to 105% for daidzin and daidzein. The detection limit was approximately 20 ng based on a signal-to-noise ratio of 3 1. 

Fluorescence and ED can provide better sensitivity compared to UV detection, but only some phytoestrogens like daidzein, formononetin, and coumestrol have fluorescence response whUe using ED at an operating potential above 1.2 V creates baseline instability." The weaknesses of these detection methods are their low sensitivity and nonspecihcity leading to the possibility of sample matrix interference." ... 

FIGURE 25.1 Structures of nonsteroidal phytoestrogens. The most prevalent classes of phytoestrogens are (1) flavones apigenin (2) kaempferol (3) isoflavones daidzein (4) genistein (5) formononetin (6) biochanin A (7) lignans enterolactone (8) coumestans coumestrol (9) flavanones 8-prenylnaringenin. 

Shemesh, M., Lindner, H.R., and Ayalon, N., Affinity of rabbit uterine oestradiol receptor for phytoestrogens and it s a competitive protein-binding radioassay for plasma coumestrol, J. Reprod. Fert., 29,1, 1972. 

Elakovich, S.D., and J.M. Hampton. 1984. Analysis of coumestrol, a phytoestrogen, in alfalfa tablets sold for human consumption. /. Agric. Food Chem. 32(1) 173-175. 

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