Metabolism of Oestrogenic Isoflavones in Sheep

Batterham, T. J.; Hart, N. K.; Lamberton, J. A.

doi:10.1038/206509a0

Cited by 52 publications

(32 citation statements)

References 3 publications

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“…The other main estrogenic compounds produced by alfalfa are the isoflavones biochanin and genistein which are metabolized in the rumen to the non-estrogenic compound 4-ethylphenol (Batterham et al, 1965;Cox and Braden, 1974). This means that their levels in forage are relatively unimportant compared with coumestrol.…”

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confidence: 99%

Alfalfa Coumestrol Content in Response to Development Stage, Fungi, Aphids, and Cultivar

et al. 2018

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Coumestrol produced by alfalfa (Medicago sativa L.) can reduce the ovulation rate of ewes. This study isolated agronomic factors that affect coumestrol levels in alfalfa. Fungal diseases explained most differences in coumestrol. Alfalfa inoculated with Stemphylium vesicarium contained 169 ± 25.1 mg kg -1 dry matter (DM) compared with 3.4 ± 0.84 mg kg -1 DM in controls. However, in field-grown alfalfa there was a low relationship (R 2 = 0.388) between coumestrol content and visual fungal damage score which indicates a need for alternative methods of prediction. In the field, a range of cultivars all reached coumestrol levels reported to pose a risk to ewe reproductive performance (>25 mg kg -1 DM). In S. vesicarium-inoculated leaves, the modern cultivar 'Stamina 5' had 396 ± 82.4 mg kg -1 DM compared with the 40-yr-old industry standard 'Wairau' at 143 ± 35.6 mg kg -1 DM. Flowering in isolation did not produce a coumestrol response, with increases detected or not detected simultaneously in vegetative and flowering plants. Pea aphids had a minor effect on coumestrol content. When alfalfa was subjected to ~5 aphids per stem for 4 wk coumestrol increased from 2.4 ± 0.39 to 5.3 ± 0.65 mg kg -1 DM. This study highlights fungal pathogens traditionally not considered problematic in alfalfa stands due to limited effects on stand persistence and yield, as important causal agents of elevated coumestrol levels. Plant breeding to reduce their impact is recommended.

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Alfalfa Coumestrol Content in Response to Development Stage, Fungi, Aphids, and Cultivar

et al. 2018

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“…The demethylating enzymes from the bacteria are important not only in the host physiology [5,31], but also in the bacterial growth and physiology [19,24,32]. The ¢rst step in the utilization of methoxylated aromatic compounds by acetogenic bacteria involves the conversion of the parent substrate to hydroxylated derivatives.…”

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Biotransformation of the isoflavonoids biochanin A, formononetin, and glycitein by Eubacterium limosum

Hur

2000

FEMS Microbiology Letters

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Eubacterium limosum (ATCC 8486), a strict anaerobe from the human intestinal tract that is capable of O-demethylation of several compounds, was tested for the ability to metabolize three methoxylated isoflavonoids, biochanin A, formononetin, and glycitein. Highperformance liquid chromatography elution profiles of metabolites produced from biochanin A, formononetin, and glycitein showed peaks that had identical retention times to authentic genistein, daidzein, and 6,7,4P-trihydroxyisoflavone, respectively. The metabolites were identified, using an on line liquid chromatography-electrospray mass spectrometer. E. limosum produced 61.4 WM of genistein and 13.2 WM of daidzein from 100 WM of biochanin A and formononetin, after 26 days incubation. O-demethylase activity is cell-associated and was not detected in the extracellular fraction of bacterial culture. This is the first study in which conversion of biochanin A, and formononetin to more potent phytoestrogens by a bacterium has been shown. ß

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“…Batterham et al 18) carried out studies in sheep and has identified p-ethylphenol as the major metabolite from genistein. They also reported that the compound was generated from the B ring and partially from the C ring of genistein and that no metabolite was detected that originated from the A ring.…”

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confidence: 99%

Urinary Metabolites of Genistein Administered Orally to Rats.

Yasuda

Ueda

Ohsawa

2001

CHEMICAL & PHARMACEUTICAL BULLETIN

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Genistein is a type of phytoestrogen found as a glucoside in glycine, the genus Sophora 1) and soy products.2) Genistein is known to have estrogenic activity, 3) a tyrosine kinase inhibitory action, 4) and a histidine kinase inhibitory action. 5)Accordingly, genistein appears to play a role in the prevention of hormone-dependent diseases such as breast and prostate cancers, osteoporosis, and coronary heart disease. [6][7][8][9] In addition to conjugation, genistein is metabolized to dihydrogenistein, equol, and p-ethylphenol. 10-14) Although many reports on the metabolites of genistein appear in the literature, there exist no systematic and detailed studies of their spectra or structure. To study the metabolism of genistein in greater detail, we used a three-dimensional (3D) HPLC equipped with a photodiode array detector as a new tool in the detection and structural identification of the metabolites.The present paper reports the structures of the urinary metabolites of genistein administered orally to rats following treatment with b-glucuronidase and arylsulfatase. Results and DiscussionThe 3D HPLC profile of urine samples from rats after oral administration of genistein showed three distinct peaks tentatively designated as M1, M2, and M3 in decreasing order of polarity. In urine samples, the parent compound was also identified as genistein by direct comparison of the UV spectrum and retention time with those of an authentic sample in 3D HPLC. M1, M2, and M3 from urine treated with enzymes were isolated by chromatographic separation on a Sephadex LH-20 column and repeated preparative HPLC, as described in the Experimental section, followed by determination of their structures.M1 was obtained as a white powder, mp 216-218°C. Its molecular formula was C 15 H 12 O 5 based on high-resolution mass spectrum (HR-MS) analysis. The UV spectrum of M1 was typical of the isoflavanone skeleton. The 1 H-NMR spectrum also suggested an isoflavanone skeleton, with a signal at d 4.48 (2H, d, Jϭ6.4 Hz, H-2) and 3.92 (1H, t, Jϭ6.4 Hz, H-3), and signal at d 5.77 (2H, s) was assigned to H-6 and H-8, respectively, and another set of A 2 B 2 -type signals at d 6.71 (2H, d, Jϭ8.6 Hz) and 7.07 (2H, d, Jϭ8.7 Hz) which were assigned to B-ring protons (H-3Ј, -5Ј, H-2Ј, -6Ј). The structure of M1 was thus concluded to be 4Ј,5,7-trihydroxyisoflavanone. As the yield of M1 was too small, the configuration at C-3 could not be determined.M2 was obtained as a white powder, mp 156-159°C, with a molecular formula determined to be C 15 H 14 O 3 from HR-electron impact (EI)-MS. The UV spectrum in methanol exhibited major absorbance at 281 nm, typical of the isoflavan skeleton. 1 H-NMR spectrum indicated that M2 possibly has hydroxyl groups at C-7 and C-4Ј. These data indicate the structure to be the known isoflavan, 4Ј,7-dihydroxyisoflavan (equol). Direct comparison of M2 by MS and NMR spectra with an authentic sample synthesized from daidzein confirmed the planar structure of M2 to be identical with that of equol. As the yield of M2 was too small, t...

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Metabolism of Oestrogenic Isoflavones in Sheep

Cited by 52 publications

References 3 publications

Alfalfa Coumestrol Content in Response to Development Stage, Fungi, Aphids, and Cultivar

Alfalfa Coumestrol Content in Response to Development Stage, Fungi, Aphids, and Cultivar

Biotransformation of the isoflavonoids biochanin A, formononetin, and glycitein by Eubacterium limosum

Urinary Metabolites of Genistein Administered Orally to Rats.

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