Isoflavones estrogenic activities

Many stilbenelike thiophene compounds have been prepared for a study of estrogenic activity, especially by Buu-Hoi et al. Thiophene derivatives of nonhydroxylated stilbene types showed no significant activitywhereas weak estrogenic activity was found in 5-acetyl-, 5-propionyl-, and 5-benzoyl-2-(-stilbenyl)thiophene. 1-Bromo-l,2-diphenyl-2-(5-bromo-2-thienyl)ethylene (258) was found to inhibit body growth and to produce extensive testicular atropy in male rats. A thiophene analog of estrogenic isoflavones (259)... 

The individual role of isoflavones contained in soy protein compared to isoflavones alone has not been systematically studied. In addition, it is possible that some of the minor components of soy also play a biological role. Nevertheless, in terms of bone health, the benefit of soy diets is largely attributed to the isoflavones due to their weak estrogenic activity and potential to alleviate the estrogen loss following the menopause. 

DOERGE D R and SHEEHAN D M (2002) Goitrogenic and estrogenic activity of soy isoflavones. Environ Health Perspect. 110 (Suppl 3) 349-53. 

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. 

Isofavonoids have a substituent at C-3. Examples are genistein and for-mononetin (see Fig. 11.11, below). Isoflavones exert estrogenic activity in mammals, interfere with reproduction in birds, and may render farm animals infertile. For example, sheep feeding on isoflavonoid-containing Trifolium suh-terraneum suffer reduced lambing (Harborne, 1993). 

Many flavonoids are known to be phytoalexins, antiviral agents, and to serve as antiinflammatory and antitumor compounds. Several isoflavones have estrogenic activity in mammals (70). (-)-Vestitol and sativan, isoflavans from Lotus species, are phytoalexins. 3R(-)-Vestitol from the resistant pasture legume Lotus pedunculatus, has been demonstrated to be a feeding deterrent... 

One concern raised about isoflavones, coumestanes, and stilbenes is that they have estrogenic activities. Indeed, some of the health benefit claims for these compounds... 

Fransworth and co-workers [8] have reported 94 plants as exhibiting estrogenic activity not all these plants are edible. Isoflavones are mainly found in legumes and particularly in soy. Soybeans and soy products are a... 

Besides the affinity of genistein, daidzein, biochanin A, formononetin, coumestrol and some other flavonoids, there is little information regarding other isoflavones, of which more than 300 have been reported to exist [6], One such example is glycitein, whose estrogenic activity has been reported in one study. The data indicated that glycitein, when fed to female mice at 3 mg/day for 4 days, produced weak estrogenic activity comparable to that of other isoflavones, but much lower than that produced by diethylstilbestrol and 17[3-estradiol [54],... 

As regards these and those previously reported, a hierarchy of estrogenic activity may be proposed, in which flavone 7, 4 -dihydroxylate has the lowest activity and coumestrol with its internal cyclation the highest, Fig. (6). Table 2 shows the relative potencies of different isoflavones and coumestrol in different models for evaluating estrogenic activity. 

CUfton-Bligh, P.B., RJ. Baber, G.R. Fulcher, M.L. Nery and T. Moreton 2001. The effect of isoflavones extracted from red clover (RimostU) on lipid and bone metabolism. Menopause 8(4) 259-265. Coon, J.T., M.H. Pittler, and E. Ernst. 2007. Trifolium pratense isoflavones in the treatment of menopausal hot flushes A systematic review and meta-analysis. Phytomedicine 14(2-3) 153-159. DerMarderosian, A., and J. Beutler. 2005. The review of natural products. 4th ed. St Louis Facts and Comparisons. Dornstauder, E., E. Jisa, I. Unterrieder, et al. 2001. Estrogenic activity of two standardized red clover extracts (Menoflavon) intended for large scale use in hormone replacement therapy.. Steroid Biochem. Mol. Biol. 78(l) 67-75. 

Documented effects A tincture of the plant is used to treat arteriosclerosis in patients with normal blood pressure (Nuraliev 1989). In modem medicine this species is used as an expectorant, diuretic, and antiseptic (Khodzhimatov 1989). Metabolites of isoflavones found in the plant were found to protect against UV radiation-induced inflammation and immunosuppression (Widyarini et al. 2001). Isoflavones found in red clover inhibited COX enzyme activity in certain cancer cell types (Lam et al. 2004). Extracts of red clover and individual flavonoid constituents exhibited estrogenic activity in a variety of in vitro assays (Overk et al. 2005). 

As previously mentioned see Chapter 11), a number of isoflavones and their derivatives also possess estrogenic activity, possibly because the overall shape of the molecules is similar to that of steroids (Farnsworth et al., 1975a, 1975b). 

Isoflavones Genistein, daidzein, formononetin (D 22.3.3) Estrogenic activity in mammals and birds... 

ISOFLAVONES ALSO COULD BE PRODUCED IN HUMAN Body Equol (49) of Isoflavone Metabolism Product with Estrogen Activity... 

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