Forage Estrogens, Relative Potencies of Several Estrogenlike Compounds Found in Forages

Bickoff, E. M.; Livingston, A. L.; Hendrickson, Alan; Booth, A. N.

doi:10.1021/jf60123a018

Cited by 154 publications

(53 citation statements)

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“…This action of phytoestrogens on PGF2α may account, at least in part, for the reproductive disorders observed in ruminants [55]. Differences in their metabolic pathways may explain why coumestrol, which maybe conjugated to both sulphates and glucuronides [2], exhibits greater oestrogenic potency than the isoflavones [56].…”

Section: Mode Of Actionmentioning

confidence: 99%

Fertility of Herbivores Consuming Phytoestrogen-containing Medicago and Trifolium Species

Reed¹

2016

Agriculture

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Despite their unrivalled value in livestock systems, certain temperate, pasture, legume species and varieties may contain phytoestrogens which can lower flock/herd fertility. Such compounds, whose chemical structure and biological activity resembles that of estradiol-17α, include the isoflavones that have caused devastating effects (some of them permanent) on the fertility of many Australian sheep flocks. While the persistence of old 'oestrogenic' ecotypes of subterranean clover (Trifolium subterraneum) in pasture remains a risk, genetic improvement has been most effective in lowering isoflavone production in Trifolium species; infertility due to 'clover disease' has been greatly reduced. Coumestans, which can be produced in Medicago species responding to stress, remain a potential risk in cultivars susceptible to, for example, foliar diseases. In the field, coumestrol is often not detected in healthy vegetative Medicago species. Wide variation in its concentration is influenced by environmental factors and stage of growth. Biotic stress is the most studied environmental factor and, in lucerne/alfalfa (Medicago sativa), it is the major determinant of oestrogenicity. Concentrations up to 90 mg coumestrol/kg (all concentrations expressed as DM) have been recorded for lucerne damaged by aphids and up to 600 mg/kg for lucerne stressed by foliar disease(s). Other significant coumestans, e.g., 4'-methoxy-coumestrol, are usually present at the same time. Concentrations exceeding 2000 mg coumestrol/kg have been recorded in diseased, annual species of Medicago. Oestrogenicity of some Medicago species is also influenced by maturity and senescence. Studies in Israel, North America, Europe, New Zealand and Australia have confirmed that coumestans in lucerne, represent an acute or sub-acute loss of reproductive efficiency in herbivores, e.g., sheep, cattle, and possibly horses. When sufficiently exposed peri-conception, coumestrol, sometimes present in lucerne, be it as pasture, hay, silage, pellets, meal, and sprouts, is associated with what can be an insidious, asymptomatic, infertility syndrome. Most livestock research with oestrogenic lucerne has been conducted with sheep. Ewes may be at risk when the coumestrol concentration in their diet exceeds 25 mg/kg. In studies where lambing was compared for lucerne and a phytoestrogen-free treatment, the mean decrease in lambs born/ewe was 13%; ewes on lucerne, exhibited a lower frequency of multiple births.

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Section: Mode Of Actionmentioning

confidence: 99%

Fertility of Herbivores Consuming Phytoestrogen-containing Medicago and Trifolium Species

Reed¹

2016

Agriculture

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“…Farmakalidis and Murphy (1985) evaluated the estrogenic activity of genistin and daidzin, the isoflavone glucosides, and showed that the glucosides had estrogenic activity equal to that of the aglycons on a molar basis. The mouse uterine enlargement assay has been the standard in vivo method to evaluate estrogenic activity (Bickoff et al, 1962), and, because it is performed in an intact animal, the effects of absorption, metabolism, serum binding, and pharmacokinetics are taken into account. These two methods were used to establish the estrogenic activity of glycitein.…”

Section: Introductionmentioning

confidence: 99%

Estrogenic Activity of Glycitein, a Soy Isoflavone

Song

Hendrich

Murphy

1999

J. Agric. Food Chem.

185

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Glycitein (4' ,7-dihydroxy-6-methoxyisoflavone) accounts for 5−10% of the total isoflavones in soy food products. The biological activity of this compound has not been reported to date, although numerous studies have been performed with the other soy isoflavones, daidzein and genistein. Glycitein was isolated from soy germ to 99% purity. Weaning female B6D2F1 mice were dosed with glycitein (3 mg/day), genistein (3 mg/ day), and diethylstilbestrol (DES) (0.03 μg/day) in 5% Tween 80 by gavage for 4 days. A control group received an equal volume of 5% Tween 80 solution daily. The uterine weight increased 150% with glycitein (p < 0.001), 50% with genistein (p < 0.001), and 60% with DES (p < 0.001) compared with the control group. DES, 17β-estradiol, and three isoflavones (daidzein, genistein, and glycitein) were examined for their competitive binding abilities with 17β-(3H)estradiol to the estrogen receptor proteins of the B6D2F1 mouse uterine cytosol. The concentrations of each compound required to displace 50% of the (3H)estradiol at 5 nM in the competitive binding assay were 1.15 nM DES, 1.09 nM 17β-estradiol, 0.22 μM genistein, 4.00 μM daidzein, and 3.94 μM glycitein. These data indicated that glycitein has weak estrogenic activity, comparable to that of the other soy isoflavones but much lower than that of DES and 17β-estradiol. Glycitein (4′,7-dihydroxy-6-methoxyisoflavone) accounts for 5-10% of the total isoflavones in soy food products. The biological activity of this compound has not been reported to date, although numerous studies have been performed with the other soy isoflavones, daidzein and genistein. Glycitein was isolated from soy germ to 99% purity. Weaning female B6D2F1 mice were dosed with glycitein (3 mg/day), genistein (3 mg/day), and diethylstilbestrol (DES) (0.03 µg/day) in 5% Tween 80 by gavage for 4 days. A control group received an equal volume of 5% Tween 80 solution daily. The uterine weight increased 150% with glycitein (p < 0.001), 50% with genistein (p < 0.001), and 60% with DES (p < 0.001) compared with the control group. DES, 17 -estradiol, and three isoflavones (daidzein, genistein, and glycitein) were examined for their competitive binding abilities with 17 -( 3 H)estradiol to the estrogen receptor proteins of the B6D2F1 mouse uterine cytosol. The concentrations of each compound required to displace 50% of the ( 3 H)estradiol at 5 nM in the competitive binding assay were 1.15 nM DES, 1.09 nM 17 -estradiol, 0.22 µM genistein, 4.00 µM daidzein, and 3.94 µM glycitein. These data indicated that glycitein has weak estrogenic activity, comparable to that of the other soy isoflavones but much lower than that of DES and 17 -estradiol.

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“…Coumestrol, a component of alfalfa (Knuckles et al, 1976) and still present in some commercial rodent diets, influences uterine growth (Ashby et al, 1999;, accelerates vaginal opening , and causes long-term effects on reproductive cycling and behavior (Whitten et al, 1995). This phytoestrogen has 10 2 -fold greater estrogenicity (Bickoff et al, 1962) than soy isoflavones, and major rodent diet manufacturers now offer phytoestrogen-reduced diets that exclude alfalfa as an ingredient. It was pointed out recently that immature rats unwittingly fed a rodent diet formulated with soy-meal and alfalfa had a near maximal uterotrophic stimulation and consequently failed to show the usual biochemical and morphological responses to exogenously administered estradiol (Boettger-Tong et al, 1998).…”

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confidence: 99%

Animal Models Impacted by Phytoestrogens in Commercial Chow: Implications for Pathways Influenced by Hormones

Brown

Setchell

2001

Laboratory Investigation

271

239

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SUMMARY:It is generally not known that most commercial rodent diets are formulated with soy protein and deliver large daily doses of isoflavones to animals throughout their lifespan, including the in utero period. Here, we demonstrate that isoflavones are bioavailable and show that commercial rodent diets universally used by animal facilities lead to very high steady-state serum isoflavone concentrations in adult rats (2613 Ϯ 873 ng/mL) and mice (2338 Ϯ 531 ng/mL), exceeding the animal's endogenous estrogen level by 30,000-to 60,000-fold. We demonstrate the maternal-fetal intrauterine transfer of isoflavones in animals fed a standard Purina 5001 soy-containing diet and show that newborn rat pups have high serum isoflavones levels (540 Ϯ 174 ng/mL) that are maintained throughout the suckling period by passage of isoflavones into maternal milk. These findings have profound implications for all animal experiments, including multigenerational studies and studies of transgenic animals, especially if biochemical or morphological end-points are influenced by the hormonal or nonhormonal properties of phytoestrogens. These compounds have the potential to modulate genotypic and phenotypic expression in general, and therefore, all investigators should be vigilant to the phytoestrogen composition of commercial rodent diets because there is a history of potent biological effects in larger animals and in humans from high circulating isoflavone concentrations. (Lab Invest 2001, 81:735-747).A lthough phytoestrogens are ubiquitous in the plant kingdom, it is soybeans and foods made with purified soy proteins that are by far the greatest contributors of isoflavones to animal and human diets (Coward et

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Forage Estrogens, Relative Potencies of Several Estrogenlike Compounds Found in Forages

Cited by 154 publications

References 4 publications

Fertility of Herbivores Consuming Phytoestrogen-containing Medicago and Trifolium Species

Fertility of Herbivores Consuming Phytoestrogen-containing Medicago and Trifolium Species

Estrogenic Activity of Glycitein, a Soy Isoflavone

Animal Models Impacted by Phytoestrogens in Commercial Chow: Implications for Pathways Influenced by Hormones

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