Inventory of phytoestrogen databases

Synthesis of 7,2'-Dihydroxy-4',5'-Dimethoxyisoflavanone, a Phytoestrogen with Derma Papilla Cell Proliferative Activity

This paper reports a concise and scalable method for the synthesis of the phytoestrogen 7,2′-dihydroxy-4′,5′-dimethoxyisoflavanone 1 via an optimized synthetic route. Compound 1 was readily obtained in 11 steps and 11% overall yield on a gram scale from commercially available 3,4-dimethoxyphenol. The key features of the synthesis include the construction of the deoxybenzoin unit through a sequence of Claisen rearrangement, oxidative cleavage, and aryllithium addition and the efficient synthesis of the isoflavanone architecture from highly functionalized 2-hydroxyketone.

Phytoestrogen intake and other dietary risk factors for low motile sperm count and poor sperm morphology

BACKGROUND

Few potentially modifiable risk factors of male infertility have been identified, and while different diets and food groups have been associated with male infertility, evidence linking dietary factors including phytoestrogens and semen quality is limited and contradictory.

OBJECTIVES

To study the associations between phytoestrogen intake and other dietary factors and semen quality.

MATERIALS AND METHODS

A case-referent study was undertaken of the male partners, of couples attempting conception with unprotected intercourse for 12 months or more without success, recruited from 14 UK assisted reproduction clinics. A total of 1907 participants completed occupational, lifestyle and dietary questionnaires before semen quality (concentration, motility and morphology) were assessed. Food intake was estimated by a 65-item food frequency questionnaire (FFQ) covering the 12 months prior to recruitment. Analyses of dietary risk factors for low motile sperm concentration (MSC: <4.8 × 10⁶ /mL) and poor sperm morphology (PM: <4% normal morphology) used unconditional logistic regression, accounting for clustering of subjects within the clinics, first without, and then with, adjustment for confounders associated with that outcome.

RESULTS

High consumption of daidzein (≥13.74 μg/d), a phytoestrogen found in soy products, was a protective factor for MSC with an odds ratio (95%CI) of 0.58 (0.42-0.82) after adjustment for clustering and potential confounding. Dietary risk factors for PM after similar adjustment showed that drinking whole milk (OR 0.67, 95%CI 0.47-0.96) and eating red meat were protective with an OR 0.67 (0.46-0.99) for eating red meat >3 times/wk.

DISCUSSION

In this case-referent study of men attending an infertility clinic for fertility diagnosis, we have identified that low MSC is inversely associated with daidzein intake. In contrast, daidzein intake was not associated with PM but eating red milk and drinking whole milk were protective.

CONCLUSIONS

Dietary factors associated with semen quality were identified, suggesting that male fertility might be improved by dietary changes.

Endocrine disruption by dietary phyto-oestrogens: impact on dimorphic sexual systems and behaviours

A wide range of health benefits have been ascribed to soya intake including a lowered risk of osteoporosis, heart disease, breast cancer, and menopausal symptoms. Because it is a hormonally active diet, however, soya can also be endocrine disrupting, suggesting that intake has the potential to cause adverse health effects in certain circumstances, particularly when exposure occurs during development. Consequently, the question of whether or not soya phyto-oestrogens are beneficial or harmful to human health is neither straightforward nor universally applicable to all groups. Possible benefits and risks depend on age, health status, and even the presence or absence of specific gut microflora. As global consumption increases, greater awareness and consideration of the endocrine-disrupting properties of soya by nutrition specialists and other health practitioners is needed. Consumption by infants and small children is of particular concern because their hormone-sensitive organs, including the brain and reproductive system, are still undergoing sexual differentiation and maturation. Thus, their susceptibility to the endocrine-disrupting activities of soya phyto-oestrogens may be especially high. As oestrogen receptor partial agonists with molecular and cellular properties similar to anthropogenic endocrine disruptors such as bisphenol A, the soya phyto-oestrogens provide an interesting model for how attitudes about what is 'synthetic' v. what is 'natural,' shapes understanding and perception of what it means for a compound to be endocrine disrupting and/or potentially harmful. This review describes the endocrine-disrupting properties of soya phyto-oestrogens with a focus on neuroendocrine development and behaviour.

Hypotensive effects of genistein: From chemistry to medicine

Genistein (4', 5, 7-trihydroxyisoflavone), a naturally occurring flavonoid characteristic of Leguminoseae plants, is a phyto-oestrogen exerting oestrogenic activity as both an agonist and an antagonist substance. A large body of evidence suggests that genistein possesses many physiological and pharmacological properties that make this molecule a potential agent for the prevention and treatment of a number of chronic diseases. Growing evidence suggests that genistein could act as a vasodilating, anti-thrombotic, and anti-atherosclerotic agent, exerting these effects through different mechanisms of action. This paper aims to review data from the literature assessing the beneficial effects of genistein on hypertension, one of the most important cardiovascular disease risk factors along with hyperglycemia and hyperlidipemia. In addition, we discuss the chemistry, main sources and bioavailability of genistein. Scientific findings support genistein's potential as a promising anti-hypertensive agent in different experimental models. However, clinical trials are very limited and more research will be required before genistein intake can be recommended as part of therapies targeting raised blood pressure.

Phase II metabolism of the soy isoflavones genistein and daidzein in humans, rats and mice: a cross-species and sex comparison

Soy isoflavones (IF) are in the focus of biomedical research since more than two decades. To assess their bioactivity, IF are investigated in rats and mice as a model. As the biological activity of IF is affected by their biotransformation, our aim was to comprehensively compare the conjugative and microbial metabolism of daidzein and genistein in adult humans, rats and mice of both sexes. One identical soy extract and a validated LC-MS method were used for all studies. We detected considerable differences between the three species. In rats and mice, sex-specific differences were observed in addition. The major plasma phase II metabolites in humans were the 7-sulfo-4'-glucuronides (39-49 %) and, in case of genistein, also the diglucuronide (34 %), whereas in mice monosulfates (33-41 %) and monoglucuronides (30-40 %) predominated. In male rats the disulfates (23-62 %) and 7-sulfo-4'-glucuronides (19-54 %) were predominant, while in female rats the 7-glucuronides (81-93 %) exhibited highest concentrations. The portion of aglycones was low in humans (0.5-1.3 %) and rats (0.5-3.1 %) but comparatively high in mice (3.1-26.0 %), especially in the case of daidzein. Furthermore, substantial differences were observed between daidzein and genistein metabolism. In contrast to humans, all rats and mice were equol producer, independent of their sex. In conclusion, there are marked differences between humans, rats and mice in the profile of major metabolites following IF phase II metabolism. These differences may contribute to resolve inconsistencies in results concerning the bioactivity of IF and should be considered when applying findings of animal studies to humans, e.g., for risk assessment.

Pueraria mirifica leaves, an alternative potential isoflavonoid source

We investigated the major leaf isoflavonoid contents of Pueraria mirifica from three different cultivars (PM-III, PM-IV, and PM-V) using reverse RP-HPLC analysis. The proportions and net levels of puerarin, daidzin, genistin, and daidzein in P. mirifica leaves were found to depend on the plant cultivar and to correlate with cultivation temperature and rainfall amount. The crude leaf-extracts were tested using the Yeast Estrogen Screen (YES) assay with both human estrogen receptors (hERα and hERβ). Their estrogenic activity was higher when determined by the YES system containing hERβ than that with hERα and was also higher when the Δsnq2 than the wildtype yeast was employed. The results open the possibility of selecting and cultivating certain P. mirifica cultivars at a farm scale to produce a sufficient supply of leaf material to act as a starting source for the commercial scale extraction of these major isoflavonoids.

Development of a food compositional database for the estimation of dietary intake of phyto-oestrogens in a group of postmenopausal women previously treated for breast cancer and validation with urinary excretion

The scientific literature contains evidence suggesting that women who have been treated for breast cancer may, as a result of their diagnosis, increase their phyto-oestrogen (PE) intake. In the present paper, we describe the creation of a dietary analysis database (based on Dietplan6) for the determination of dietary intakes of specific PE (daidzein, genistein, glycitein, formononetin, biochanin A, coumestrol, matairesinol and secoisolariciresinol), in a group of women previously diagnosed and treated for postmenopausal breast cancer. The design of the database, data evaluation criteria, literature data entry for 551 foods and primary analysis by LC–MS/MS of an additional thirty-four foods for which there were no published data are described. The dietary intake of 316 women previously treated for postmenopausal breast cancer informed the identification of potential food and beverage sources of PE and the bespoke dietary analysis database was created to, ultimately, quantify their PE intake. In order that PE exposure could be comprehensively described, fifty-four of the 316 subjects completed a 24 h urine collection, and their urinary excretion results allowed for the description of exposure to include those identified as ‘equol producers’.

The pros and cons of phytoestrogens

Phytoestrogens are plant derived compounds found in a wide variety of foods, most notably soy. A litany of health benefits including a lowered risk of osteoporosis, heart disease, breast cancer, and menopausal symptoms, are frequently attributed to phytoestrogens but many are also considered endocrine disruptors, indicating that they have the potential to cause adverse health effects as well. Consequently, the question of whether or not phytoestrogens are beneficial or harmful to human health remains unresolved. The answer is likely complex and may depend on age, health status, and even the presence or absence of specific gut microflora. Clarity on this issue is needed because global consumption is rapidly increasing. Phytoestrogens are present in numerous dietary supplements and widely marketed as a natural alternative to estrogen replacement therapy. Soy infant formula now constitutes up to a third of the US market, and soy protein is now added to many processed foods. As weak estrogen agonists/antagonists with molecular and cellular properties similar to synthetic endocrine disruptors such as Bisphenol A (BPA), the phytoestrogens provide a useful model to comprehensively investigate the biological impact of endocrine disruptors in general. This review weighs the evidence for and against the purported health benefits and adverse effects of phytoestrogens.

Guidance from an NIH workshop on designing, implementing, and reporting clinical studies of soy interventions

The NIH sponsored a scientific workshop, "Soy Protein/Isoflavone Research: Challenges in Designing and Evaluating Intervention Studies," July 28-29, 2009. The workshop goal was to provide guidance for the next generation of soy protein/isoflavone human research. Session topics included population exposure to soy; the variability of the human response to soy; product composition; methods, tools, and resources available to estimate exposure and protocol adherence; and analytical methods to assess soy in foods and supplements and analytes in biologic fluids and other tissues. The intent of the workshop was to address the quality of soy studies, not the efficacy or safety of soy. Prior NIH workshops and an evidence-based review questioned the quality of data from human soy studies. If clinical studies are pursued, investigators need to ensure that the experimental designs are optimal and the studies properly executed. The workshop participants identified methodological issues that may confound study results and interpretation. Scientifically sound and useful options for dealing with these issues were discussed. The resulting guidance is presented in this document with a brief rationale. The guidance is specific to soy clinical research and does not address nonsoy-related factors that should also be considered in designing and reporting clinical studies. This guidance may be used by investigators, journal editors, study sponsors, and protocol reviewers for a variety of purposes, including designing and implementing trials, reporting results, and interpreting published epidemiological and clinical studies.

Systematic analysis of the content of 502 polyphenols in 452 foods and beverages: an application of the phenol-explorer database

Considerable information on polyphenol content in foods is scattered in up to 1000 peer-reviewed publications and is therefore not easily exploited. Over 60000 food composition data have been collected from this literature and stored in the new Phenol-Explorer database ( www.phenol-explorer.eu ). Thirty-seven thousand data were selected after evaluation and aggregated separately according to 5 categories of analytical methods to generate mean content values for 502 compounds (glycosides, esters, or aglycones) in 452 foods. These data are exploited here in a first systematic analysis of the content in foods of these 502 polyphenols. These data will be useful for epidemiologists to determine polyphenol intake and associations with health and diseases in populations and for food scientitsts and food manufacturers to develop new products with optimized properties.