Bioavailability of soybean isoflavones depends upon gut microflora in women

The Impact of Fermented Dairy Products and Probiotics on Bone Health Improvement

The bone is an important body organ due to its role in locomotion, protection and mineral homeostasis. Bone health is affected by various intrinsic and extrinsic factors like genetics, diet, environment and immune status of an individual. Being a dynamic organ, bones are continuously being remodeled and the remodeling is mediated by an intricate balance of bone formation and resorption which, in turn, are regulated by environmental, genetic, hormonal and neural factors. Lack of balance in any of these factors leads to bone disorders such as osteoporosis. Fermented dairy products along with their probiotics content play a significant role in bone remodeling process ensuring the maintenance of intricate balance in bone forming cells (osteoblasts) and bone resorbing cells (osteoclasts). Proteins and various minerals are important constituents of bone. Dairy products, especially fermented ones, are significant because of being a good source of proteins and minerals required to make and maintain a healthy bone. In addition, these provide the body with probiotics which are involved in bone health improvement by enhancing the bioavailability of dietary constituents, production of short chain fatty acids and reducing the inflammatory components. Hence, fermented dairy products should be a regular part of our diet to keep our bone healthy.

The Role of Genistein in Type 2 Diabetes and Beyond: Mechanisms and Therapeutic Potential

The global prevalence of type 2 diabetes mellitus (T2DM) necessitates the exploration of novel therapeutic approaches to mitigate its complex molecular pathogenesis. This review investigates the potential role of genistein, a prominent isoflavone derived from soybeans, in the management of T2DM. Recognized for its selective estrogen receptor modulator (SERM) activity, genistein exerts a multifaceted influence on key intracellular signaling pathways, which are crucial in regulating cell proliferation, apoptosis, and insulin signaling. Genistein's anti-inflammatory, anti-oxidant, and metabolic regulatory properties position it as a promising candidate for T2DM intervention. This review synthesizes current research spanning preclinical studies and clinical trials, emphasizing genistein's impact on insulin sensitivity, glucose metabolism, and inflammatory markers. Additionally, this review addresses genistein's bioavailability, safety, and potential influence on gut microbiota composition. By consolidating these findings, this review aims to provide a comprehensive understanding of genistein's therapeutic potential in T2DM management, offering valuable insights for future research and clinical practice.

Perspective on the Coevolutionary Role of Host and Gut Microbiota in Polyphenol Health Effects: Metabotypes and Precision Health

"Personalized nutrition" aims to establish nutritional strategies to improve health outcomes for non-responders. However, it is utopian since most people share similar nutritional requirements. "Precision health," encompassing lifestyles, may be more fitting. Dietary (poly)phenols are "healthy" but non-nutritional molecules (thus, we can live without them). The gut microbiota influences (poly)phenol effects, producing metabolites with different activity than their precursors. Furthermore, producing distinctive metabolites, like urolithins, lunularin, and equol, leads to the term "polyphenol-related gut microbiota metabotypes," grouping individuals based on a genuine microbial metabolism of ellagic acid, resveratrol, and isoflavones, respectively. Additionally, (poly)phenols exert prebiotic-like effects through their antimicrobial activities, typically reducing microbial diversity and modulating microbiota functionality by impacting its composition and transcriptomics. Since the gut microbiota perceives (poly)phenols as a threat, (poly)phenol effects are mostly a consequence of microbiota adaptation through differential (poly)phenol metabolism (e.g., distinctive reductions, dehydroxylations, etc.). This viewpoint is less prosaic than considering (poly)phenols as essential nutritional players in human health, yet underscores their health significance in a coevolutionary partnership with the gut microbiota. In the perspective on the gut microbiota and (poly)phenols interplay, microbiota metabotypes could arbiter health effects. An innovative aspect is also emphasized: modulating the interacting microbial networks without altering the composition.

Mechanisms of gut bacterial metabolism of dietary polyphenols into bioactive compounds

The fruits and vegetables we consume as part of our diet are rich in bioactive metabolites that can prevent and ameliorate cardiometabolic diseases, cancers, and neurological conditions. Polyphenols are a major metabolite family that has been intensively investigated in this context. However, for these compounds to exert their optimal bioactivity, they rely on the enzymatic capacity of an individual's gut microbiota. Indeed, for most polyphenols, the human host is restricted to more basic metabolism such as deglycosylation and hepatic conjugation. In this review, we discuss the mechanisms by which gut bacteria metabolize the core scaffold of polyphenol substrates, and how their conversion into bioactive small molecules impacts host health.

Genistein Co-Amorphous Systems with Amino Acids: An Investigation into Enhanced Solubility and Biological Activity

Genistein, an isoflavone known for its antioxidant and antidiabetic effects, suffers from the drawback of low solubility. To overcome this limitation, co-amorphous systems were synthesized by incorporating amino acids that were chosen through computational methods. The confirmation of the amorphous state of lysine and arginine-containing systems was ascertained by X-ray powder diffraction. Subsequently, the characterization of these systems was extended by employing thermo-gravimetry, differential scanning calorimetry, Fourier-transform infrared spectroscopy, and scanning electron microscopy. The investigation also included an assessment of the physical stability of the samples during storage. The apparent solubility of the systems was studied in an aqueous medium. To evaluate the in vitro permeability through the gastrointestinal tract, the parallel artificial membrane permeability assay was employed. The biological properties of the systems were assessed with regard to their antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl and cupric ion-reducing antioxidant capacity assays, as well as their ability to inhibit α-glucosidase. The systems' glass transition temperatures were determined, and their homogeneity confirmed via differential scanning calorimetry analysis, while Fourier-transform infrared spectroscopy analysis provided data on molecular interactions. Stability was maintained for the entire 6-month storage duration. The co-amorphous system containing lysine displayed the most pronounced apparent solubility improvement, as well as a significant enhancement in antioxidant activity. Notably, both systems demonstrated superior α-glucosidase inhibition relative to acarbose, a standard drug for managing type 2 diabetes. The results indicate that co-amorphous systems with lysine and arginine have the potential to significantly enhance the solubility and biological activity of genistein.

Protective effect of phytoestrogens on nonalcoholic fatty liver disease in postmenopausal women

Non-alcoholic fatty liver disease (NAFLD) is a progressive metabolic disease characterized by hepatic steatosis, inflammation, and fibrosis that seriously endangers global public health. Epidemiological studies have shown that the incidence of non-alcoholic fatty liver disease in postmenopausal women has significantly increased. Studies have shown that estrogen deficiency is the main reason for this situation, and supplementing estrogen has become a new direction for preventing the occurrence of postmenopausal fatty liver. However, although classical estrogen replacement therapy can reduce the incidence of postmenopausal NAFLD, it has the risk of increasing stroke and cardiovascular diseases, so it is not suitable for the treatment of postmenopausal NAFLD. More and more recent studies have provided evidence that phytoestrogens are a promising method for the treatment of postmenopausal NAFLD. However, the mechanism of phytoestrogens in preventing and treating postmenopausal NAFLD is still unclear. This paper summarizes the clinical and basic research evidence of phytoestrogens and reviews the potential therapeutic effects of phytoestrogens in postmenopausal NAFLD from six angles: enhancing lipid metabolism in liver and adipose tissue, enhancing glucose metabolism, reducing oxidative stress, reducing the inflammatory response, regulating intestinal flora, and blocking liver fibrosis (Graphical Abstract).

Understanding the Phytoestrogen Genistein Actions on Breast Cancer: Insights on Estrogen Receptor Equivalence, Pleiotropic Essence and Emerging Paradigms in Bioavailability Modulation

Prevalent as a major phenolic ingredient of soy and soy products, genistein is recognized as an eminent phytoestrogen owing to its interacting ability with estrogen receptors (ERs). The metabolic conversion of plant-derived genistin to genistein by gut microbes and intestinal enzymes enhances its absorption at intestinal pH of ~7.5-7.8. Genistein interferes in breast cancer (BC) development via pleiotropic actions on cell proliferation, survival, angiogenesis, and apoptosis. Though multiple investigations have demonstrated genistein intake-driven reduced BC risk, similar efficacy has not been replicated in clinical trials. Furthermore, multiple studies have structurally and functionally equated genistein extents with 17-β-estradiol (E2), the most available physiological estrogen in females, culminating in aggravated BC growth. Of note, both genistein and E2 function via interacting with ERs (ERα and ERβ). However, although E2 shows almost equal affinity towards both ERα and ERβ, genistein shows more affinity towards ERβ than ERα. Our cautious literature survey revealed typical intake mode, ER expression pattern and the ratio of ERα and ERβ, transactivators/ regulators of ERα and ERβ expression and activities, patient age, and menopausal status as decisive factors affecting genistein BC activities. Of further interest are the mechanisms by which genistein inhibits triple-negative breast cancers (TNBCs), which lack ERs, progesterone receptors (PRs), and human epidermal growth factor receptors (HER2). Herein, we attempt to understand the dosage-specific genistein actions in BC cells and patients with an insight into its better response via derivative development, nanocarrier-assisted, and combinatorial delivery with chemotherapeutic drugs.

Gut microbiota and acylcarnitine metabolites connect the beneficial association between equol and adiposity in adults: a prospective cohort study

BACKGROUND

Many studies have investigated the effects of soy isoflavones on weight control, but few have focused on the role of equol, a gut-derived metabolite of daidzein with greater bioavailability than other soy isoflavones.

OBJECTIVES

This study examined the association of equol production with obesity and explored the mediating roles of equol-related gut microbiota and microbial carnitine metabolites.

METHODS

This 6.6-y prospective study included 2958 Chinese adults (2011 females and 947 males) aged 60.6 ± 6.0 y (mean ± SD) at baseline. Urinary equol and isoflavones were measured using HPLC-tandem MS. BMI, percentage fat mass (%FM), and serum triglycerides (TGs) were assessed every 3 y. Metagenomics sequencing and assessment of carnitine metabolites in feces were performed in a subsample of 897 participants.

RESULTS

Urinary equol, but not daidzein and genistein, was independently and inversely associated with the obesity-related indicators of BMI, %FM, and a biomarker (TGs). Equol producers (EPs) had lower odds of adiposity conditions and a reduced risk of 6.6-y obesity progression than non-EPs among total participants. Gut microbial analyses indicated that EPs had higher microbiome species richness (P = 3.42 × 10-5) and significantly different β-diversity of gut microbiota compared with the non-EP group (P = 0.001), with 20 of 162 species differing significantly. EPs (compared with non-EPs) had higher abundances of Alistipes senegalensis and Coprococcus catus but lower abundances of Ruminococcus gnavus (false discovery rate <0.05). Among the 7 determined fecal acylcarnitine metabolites, palmitoylcarnitine, oleylcarnitine 18:1, and stearylcarnitine were inversely associated with EPs but positively correlated with obesity conditions and progression. Path analyses indicated that the beneficial association between equol and obesity might be mediated by gut microbiota and decreased production of 3 acylcarnitines in feces.

CONCLUSIONS

This study suggests a beneficial association between equol and obesity, mediated by the gut microbiome and acylcarnitines, in adults.This trial was registered at clinicaltrials.gov as NCT03179657.

The Intake of Antioxidant Capacity of Children Depends on Their Health Status

The gastrointestinal digestion of food and further gut microbial activity render a myriad of different molecules that could be responsible for the biological activities that are classically assigned to their parent compounds. This has been previously shown for some phytochemicals whose antioxidant capacity was either increased or decreased after being metabolized by gut microbes. Whether a global antioxidant capacity that is extracted from food is determined by the gut microbial community structure is still not well described. In the present study, we in vitro digested and fermented 48 different foods that were submitted to different culinary treatments using the stools of lean children, obese children, celiac children and children with an allergy to cow’s milk proteins. Their antioxidant capacities were assessed with the DPPH and FRAP assays, and the percentage that each food contributed to their daily antioxidant intake as well as their antioxidant capacity by portion size was inferred. Overall, cereals, fruits and vegetables displayed a higher contribution to their daily antioxidant intake, while tubers, fish and meat exhibited a higher antioxidant capacity by serving size. The food that was fermented in the lean children’s and those children that were allergic to cow’s milk protein’s fecal material, showed a higher antioxidant capacity, which could imply that there is a larger role of the gut microbiota in this area.

The role of isoflavones in augmenting the effects of radiotherapy

Cancer is one of the major health problems and the second cause of death worldwide behind heart disease. The traditional soy diet containing isoflavones, consumed by the Asian population in China and Japan has been identified as a protective factor from hormone-related cancers. Over the years the research focus has shifted from emphasizing the preventive effect of isoflavones from cancer initiation and promotion to their efficacy against established tumors along with chemo- and radiopotentiating effects. Studies performed in mouse models and results of clinical trials emphasize that genistein or a mixture of isoflavones, containing in traditional soy diet, could be utilized to both potentiate the response of cancer cells to radiotherapy and reduce radiation-induced toxicity in normal tissues. Currently ongoing clinical research explores a potential of another significant isoflavone, idronoxil, also known as phenoxodiol, as radiation enhancing agent. In the light of the recent clinical findings, this article reviews the accumulated evidence which support the clinically desirable interactions of soy isoflavones with radiation therapy resulting in improved tumor treatment. This review discusses important aspects of the development of isoflavones as anticancer agents, and mechanisms potentially relevant to their activity in combination with radiation therapy of cancer. It gives a critical overview of studies characterizing isoflavone targets such as topoisomerases, ENOX2/PMET, tyrosine kinases and ER receptor signaling, and cellular effects on the cell cycle, DNA damage, cell death, and immune responses.

Neurocognitive Effects of Cocoa and Red-Berries Consumption in Healthy Adults

In recent decades, the elderly population has increased at higher rates than any other population group, resulting in an increase in age-related diseases such as neurodegenerative and cognitive impairment. To address this global health problem, it is necessary to search for new dietary strategies that can prevent the main neurocognitive problems associated with the ageing process. Therefore, the aim of the present study was to analyze the effect of cocoa flavanols and red berry anthocyanins on brain-derived neurotrophic factor (BDNF) and nerve growth factor receptor (NGF-R) and to stablish the possible improvement in cognitive performance by using a battery of neurocognitive tests that included the Verbal Learning Test Spain-Complutense, the Spatial Recall Test 10/36 BRB-N, the Wechsler Adult Intelligence Scale III and IV, the STROOP Task and the Tower of London Test. A randomized, double-blind, parallel-group study was performed in 60 healthy volunteers between 50 and 75 years old who consumed a cocoa powder, a red berries mixture or a combination of both for 12 weeks. After the intervention, we observed a reduction in the time needed to start (p = 0.031) and finish (p = 0.018) the neurocognitive test known as the Tower of London in all groups, but the decrease in time to finish the task was more pronounced in the intervention with the combination of cocoa-red berries group. We failed to show any significant difference in BDNF and NGF-R sera levels. However we found a negative correlation between BDNF and the number of movements required to finish the TOL in women (p = 0.044). In conclusion, our study showed an improvement in executive function, without any change in neurotrofin levels, for all intervention arms.

Association between Equol Production Status and Nonalcoholic Steatohepatitis

Equol is a metabolite of daidzein, a major soybean isoflavone with estrogenic and antioxidant activities. As the production of equol depends on the presence of certain members of the intestinal microflora, not all individuals can produce equol. We examined the relationship between NASH histological features and equol production. In an animal model, obese OLETF rats were intraperitoneally injected with a porcine serum to augment liver fibrogenesis. Equol-rich soy product, SE5-OH was orally administered during the experimental period. Treatment with SE5-OH markedly attenuated the development of liver fibrosis and expression of alpha-smooth muscle actin. In clinical research, 38 NAFLD patients (13 men and 25 women) were included. The degree of fibrosis and ballooning in equol-nonproducers was significantly higher than in equol-producers in women. The percentage of nonproducers with NAFLD activity score (NAS) ≥ 5 was significantly higher than that of producers. None of the histological features were significantly different between nonproducers and producers in men. Decision tree analysis identified predictors for NAS ≥ 5 in women. The status of equol production was the strongest predictor, followed by fasting glucose. Since equol can be noninvasively detected in urine, it can be applied as a screening tool for the progression of NASH in women.

Effects of novel flavonoid-enriched yogurt on the diversity of intestinal microbiota in mice

Soy isoflavone glycoside cannot be effectively absorbed by the human intestinal tract, but probiotics with related hydrolases can transform it into aglycone to promote its absorption. In this study, a novel flavonoid-enriched yogurt was developed using an isolated β-glucosidase-producing strain (Lactiplantibacillus plantarum GY). The flavonoid aglycone-enhanced yogurt was fed to ICR mice for 21 days, and its effects were observed. The yogurt can affect the gut microbial diversity of mice, especially increasing the abundance of Parasutterella, the Bacteroidales S24-7 group, and Phascolarctobacterium in the intestinal tract of mice. Meanwhile, the ratio of Bacteroidetes/Firmicutes in the intestinal tract of mice fed with the flavonoid aglycone-enriched yogurt increased. The difference in the content of butyric acid between the L-GY + IS and the control groups was significant (P < 0.05). Therefore, milk fermentation with β-glucosidase-producing strains is a promising approach for developing flavonoid glycoside-enriched yogurt products.

Optimization of the Bioactivation of Isoflavones in Soymilk by Lactic Acid Bacteria

Soybeans and soy-based products contain isoflavones which can be used for nutraceutical and medical applications. In soybeans and in unfermented soy foods, isoflavones are normally present as glycosides. Isoflavone glycosides can be enzymatically converted to isoflavone aglycones, thus releasing the sugar molecule. The effective absorption of isoflavones in humans requires the bioconversion of isoflavone glycosides to isoflavone aglycones through the activity of the enzyme β-glucosidase. The objective was to assess the capacity of 42 bacterial strains (belonging to Lactobacillus, Streptococcus and Enterococcus) to produce β-glucosidase activity. The strain that showed the highest β-glucosidase activity (Lactobacillus plantarum 128/2) was then used for the optimization of the bioconversion of genistin and daidzin present in commercial soymilk to their aglycone forms genistein and daidzein. The contribution of process parameters (temperature, inoculum size, time) to the efficiency of such bioactivation was tested. Lactobacillus plantarum 128/2 was able to completely bioactivate soymilk isoflavones under the following conditions: 25 °C temperature, 2% inoculum size and 48 h process time. These results confirm the suitability of lactic acid bacteria for the bioactivation of isoflavones present in soymilk and provide an interesting candidate (L. plantarum 182/2) for food industries to perform this transformation.

Relevance of the Isoflavone Absorption and Testicular Function: A Systematic Review of Preclinical Evidence

Isoflavone is a phytoestrogen found in different types of food that can act as endocrine disrupters leading to testicular dysfunction. Currently, fragmented data on the action of this compound in the testicles make it difficult to assess its effects to define a safe dose. Thus, we systematically reviewed the preclinical evidence of the impact of isoflavone on testicular function. We also determined which form (aglycones or glycosylated) was the most used, which allowed us to understand the main biological processes involved in testicular function after isoflavone exposure. This systematic review was carried out according to the PRISMA guidelines using a structured search on the biomedical databases MEDLINE (PubMed), Scopus, and Web of Science, recovering and analyzing 22 original studies. The bias analysis and the quality of the studies were assessed by the criteria described in the risk of bias tool developed by SYRCLE (Systematic Review Centre for Laboratory Animal Experimentation). The aglycones and glycosylated isoflavones proved to be harmful to the reproductive health, and the glycosylates at doses of 50, 100, 146, 200, 300, 500, and 600 mg/kg, in addition to 190 and 1000 mg/L, appear to be even more harmful. The main testicular pathologies resulting from the use of isoflavones are associated with Leydig cells resulting from changes in molecular functions and cellular components. The most used isoflavone to evaluate testicular changes was the genistein/daidzein conjugate. The consumption of high doses of isoflavones promotes changes in the functioning of Leydig cells, inducing testicular changes and leading to infertility in murine models.

Urinary equol is associated with bioavailable testosterone but not total testosterone in women

Little is known about the association between equol and bioavailable testosterone (BT) in adults. In this study, we examined the associations of urinary equol concentrations with serum concentrations of total, bioavailable and free testosterone (FT), dehydroepiandrosterone sulfide (DHEAS), free androgen index (FAI) and sex hormone-binding globulin (SHBG). This cross-sectional study included 1,904 women with a mean age of 59.7 years. Urinary equol concentrations were measured using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The serum androgenic indices and SHBG were also determined. Overall, urinary equol tended to be inversely associated with bioactive forms of androgenic indices (BT, FT or FAI) but not with total testosterone (TT) or DHEAS. Urinary equol was also positively associated with SHBG. In multi-covariate-adjusted analyses stratified by menopausal status, graded and inverse associations between urinary equol and bioactive forms of androgenic indices (BT, FT and FAI) were observed in postmenopausal women (all p-trends < 0.05), but not in premenopausal women. A significant positive association between urinary equol and SHBG was observed only in postmenopausal women. No significant associations were observed between urinary equol and TT or DHEAS in either group. A path analysis indicated that these associations of equol with androgens in postmenopausal women might be mediated by SHBG. In conclusion, urinary equol exhibited graded and inverse associations with BT or FT, but not TT in women. However, further longitudinal studies of human patients are needed to confirm these results and overcome the limitations of cross-sectional studies.

Altered Gut Microbiota Composition Is Associated With Back Pain in Overweight and Obese Individuals

Background: Back pain is the leading cause of disability worldwide and is associated with obesity and chronic low-grade inflammation. Alterations in intestinal microbiota may contribute to the pathogenesis of back pain through metabolites affecting immune and inflammatory responses. Aims and Methods: We compared the gut microbiota composition in a cohort of 36 overweight or obese individuals with or without self-reported back pain in the preceding month. Participants were characterized for anthropometry; bone health; metabolic health; inflammation; dietary intake; and physical activity. Results: Demographic, clinical, biochemical characteristics, diet and physical activity were similar between participants with (n = 14) or without (n = 22) back pain. Individuals with back pain had a higher abundance of the genera Adlercreutzia (p = 0.0008; FDR = 0.027), Roseburia (p = 0.0098; FDR = 0.17), and Uncl. Christensenellaceae (p = 0.02; FDR = 0.27) than those without back pain. Adlercreutzia abundance remained higher in individuals with back pain in the past 2 weeks, 6 months, and 1 year. Adlercreutzia was positively correlated with BMI (rho = 0.35, p = 0.03), serum adipsin (rho = 0.33, p = 0.047), and serum leptin (rho = 0.38, p = 0.02). Conclusions: Our findings suggest that back pain is associated with altered gut microbiota composition, possibly through increased inflammation. Further studies delineating the underlying mechanisms may identify strategies for lowering Adlercreutzia abundance to treat back pain.

Gender Differences in Phytoestrogens and the Relationship with Speed of Processing in Older Adults: A Cross-Sectional Analysis of NHANES, 1999-2002

Sex hormone changes in adults are known to play a part in aging, including cognitive aging. Dietary intake of phytoestrogens can mimic estrogenic effects on brain function. Since sex hormones differ between genders, it is important to examine gender differences in the phytoestrogen–cognition association. Therefore, the goal of this study is to examine the relationship between urinary phytoestrogens and speed of processing (SOP) and the variation of the association between genders in older adults. Participants were drawn from the 1999–2002 National Health and Nutrition Examination Survey and included 354 individuals aged 65–85 years old. General linear models (GLMs) were used to test for significant gender differences in the relationship between phytoestrogens and SOP. Results from the GLMs showed significant gender differences in the relationship between genistein and SOP. Higher levels of genistein were associated with better SOP in women. This relationship was reversed in men: higher genistein levels were associated with worse performance. Results indicate that there are distinct gender differences in the relationship between genistein and SOP. These results emphasize the importance of considering gender differences when devising dietary and pharmacologic interventions that target phytoestrogens to improve brain health.

Phytoestrogens: Dietary Intake, Bioavailability, and Protective Mechanisms against Colorectal Neoproliferative Lesions

Phytoestrogens are natural substances that have been extensively studied for their beneficial effect on human health. Herein, we analyzed the data of the literature on the role of phytoestrogens in the prevention of colorectal neoproliferative lesions (CNL). Both in vitro and in vivo studies suggest that the beneficial effects of phytoestrogens on CNL mainly depend on their ability to bind estrogen receptor beta (ERβ) in the intestinal mucosa and counter ER-alpha (ERα) activity. Epidemiological data demonstrate a correlation between the low prevalence of CNL in Eastern populations and the consumption of soy products (phytoestrogen-enriched diet). However, both observational and interventional studies have produced inconclusive results. In our opinion, these discrepancies depend on an inadequate evaluation of phytoestrogen intake (dietary questionnaires were not aimed at establishing phytoestrogen intake) and absorption (depending mainly on the intestinal microbiota of the analyzed subjects). For this reason, in the present review, we performed an overview of phytoestrogen dietary intake and metabolism to offer the reader the opportunity for a better interpretation of the literature. Future prospective trials focusing on the protective effect of phytoestrogens against CNL should take into account both their dietary intake and absorption, considering the effective role of the intestinal microbiota.

Equol inhibits growth and spore formation of Clostridioides difficile

AIMS

Equol is a nonsteroidal oestrogen of the isoflavone class. We investigated the antibacterial ability of equol with respect to the growth rate, toxin production and spore-forming abilities of Clostridioides difficile BI/027/NAP1.

METHODS AND RESULTS

Isoflavones, or female hormones, were added to bacterial culture, which was grown at 35°C. The absorbance of the culture was measured at various time points for evaluating the growth inhibition. The toxin levels in the media and morphological changes were also assessed. To evaluate the influence of equol on the sporulation of C. difficile, cells were collected at various time points from the equol-supplemented culture and the number of spores was counted. Our results show that equol inhibits bacterial growth in a concentration-dependent manner. However, it does not inhibit the production of toxin by C. difficile. Other isoflavones and female hormones did not inhibit the C. difficile growth. At the 14th day, approximately 600 spores were present in the control medium and only six were seen in the equol-containing medium.

CONCLUSION

Our results suggest that equol may directly inhibit the C. difficile growth in a concentration-dependent manner and spore formation.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report on the antimicrobial ability of equol.

Urinary equol, but not daidzein and genistein, was inversely associated with the risk of type 2 diabetes in Chinese adults

PURPOSE

Many studies have examined the association of isoflavone intake with type 2 diabetes (T2D), and produced inconsistent results. Few studies, however, explored the association using objective biomarkers (particular for daidzein metabolite-equol) of isoflavones. We aimed to explore the association of urinary equol, daidzein and genistein concentrations with T2D and examine the mediating roles of high-sensitivity C-reactive protein (hsCRP) and retinol binding protein 4 (RBP4).

METHODS

This prospective study included 2818 subjects. Urinary concentrations of equol, daidzein and genistein were measured by high-performance liquid chromatography-tandem mass spectrometry. The associations between urinary isoflavones and T2D incidence were evaluated by cox proportional hazards model.

RESULTS

After adjustment for covariates, urinary equol except daidzein and genistein was inversely associated with T2D incidence. In comparison with the first tertile, multivariable adjusted hazard ratios (HRs) and 95% confidence intervals (95% CIs) for T2D incidence in the second and third tertile of equol concentration were 0.52 (0.37, 0.73) and 0.72 (0.53, 0.97), respectively. In stratified analyses by sex, the HR (95% CI) of men in the second vs. first tertile of equol was 0.29 (0.14, 0.58). Equivalent estimation in women was 0.67 (0.45, 1.01). Neither women nor men in the third tertile showed significant difference of T2D incidence compared with the first tertile. In path analyses, there was no evidence of mediating effects of hsCRP and RBP4 on the "equol-T2D" relationship.

CONCLUSIONS

Urinary equol was favorably associated with a decreased T2D incidence in Chinese adults. The equol-T2D relationship might not be mediated by hsCRP and RBP4.

TRIAL REGISTRATION

This study has been registered at http://www.clinicaltrials.gov as NCT03179657.

The effect of different processing methods on nutrient and isoflavone content of soymilk obtained from six varieties of soybean grown in Rwanda

Soymilk is rich in nutrients and isoflavones, and could greatly promote nutrition and health. However, this product is not widely accepted due to an objectionable beany flavor. Several methods involving heat treatment and soaking in basic solutions prior to soymilk extraction have been reported to reduce the objectionable flavor. However, the effects of such treatments on the nutritional value and isoflavone content of soymilk, and the responses of different soybean varieties to nutrient extraction by these methods is not well studied. The aim of this study was to determine the effect of three processing methods on protein, fat, minerals, and isoflavone content in soymilk from six soybean varieties grown in Rwanda (Peka-6, SB 24, Sc. Sequel, Sc, Squire, and a local variety) to find the best variety and processing method. The first method (M1) involved soaking soybeans in water for 12 hr prior to milk extraction, M2 involved blanching in NaHCO 3 prior to extraction and M3 involved soaking in NaHCO 3 solution for 16 hr and subsequent cooking prior to extraction. M1 resulted in significantly higher nutrient and isoflavone extraction than M2 and M3. Thus, M1 extracted more nutrients and can be recommended for soymilk production. However, where consumers prefer soymilk obtained by M2 or M3, Sc Squire and the local variety may be recommended. Sc. Squire has another advantage of higher isoflavone content than the other varieties. Further comprehensive studies on the sensory acceptability of products made from different varieties by different methods among different consumer categories will be necessary.

A highly glucose-tolerant GH1 β-glucosidase with greater conversion rate of soybean isoflavones in monogastric animals

In the feed industry, β-glucosidase has been widely used in the conversion of inactive and bounded soybean isoflavones into active aglycones. However, the conversion is frequently inhibited by the high concentration of intestinal glucose in monogastric animals. In this study, a GH1 β-glucosidase (AsBG1) with high specific activity, thermostability and glucose tolerance (IC50 = 800 mM) was identified. It showed great glucose tolerance against substrates with hydrophobic aryl ligands (such as pNPG and soy isoflavones). Using soybean meal as the substrate, AsBG1 exhibited higher hydrolysis efficiency than the GH3 counterpart Bgl3A with or without the presence of glucose in the reaction system. Furthermore, it is the first time to find that the endogenous β-glucosidase of soybean meal, mostly belonging to GH3, plays a role in the hydrolysis of soybean isoflavones and is highly sensitive to glucose. These findings lead to a conclusion that the GH1 rather than GH3 β-glucosidase has prosperous application advantages in the conversion of soybean isoflavones in the feed industry.

Effects of Equol Supplement on Bone and Cardiovascular Parameters in Middle-Aged Japanese Women: A Prospective Observational Study

Objective: To examine changes in the bone and cardiovascular parameters and tolerability in middle-aged Japanese women taking equol supplement for a year.

Design: This was a prospective observational study.

Subjects and Setting: Participants were 74 women receiving outpatient care at Hamasite Medical Clinic, Minato-ku, Tokyo, from 2013 to 2015.

Interventions: Participants received per oral equol-containing supplement, 10 mg/day.

Outcome measures: The primary outcome measures were percent changes in bone and cardiovascular parameters after 1 year supplementation with equol. The secondary measures included factors affecting the parameter changes and adverse effects associated with equol use for a year.

Results: Reduction in arterial stiffness was observed after 12 months of equol supplement (1402.3 cm/s vs.1367.3 cm/s, p < 0.001). Significant reductions in respective parameters were observed in women with moderate and high risk for arteriosclerosis (median [95% confidence interval]: −3.2% [−5.79 to −0.74]; −12.65% [−18.52 to −4.28]; respectively); hypertriglyceridemia −45.53% [−70.24 to −5.58]; bone resorption risk (−15.15% [−23.71 to 1.56]; and bone fracture risk −26.68% [−76.43 to −5.99]. All 15 women with high baseline parathyroid hormone levels had achieved a median of 50% [−54.11 to −31.69] reduction from their baseline values. These associations were further confirmed in the results of multiple linear regression analysis. There were no reported adverse events or abnormal findings in the blood chemistry, Pap smear, mammography, and transvaginal ultrasound during periodic follow-ups.

Conclusion: One year equol supplement was tolerable and induced improvement of certain bone and cardiovascular parameters, especially in higher risk groups. Further controlled studies are needed to explore long-term equol use for wellbeing of middle-aged women.

Soybean soluble polysaccharide enhances absorption of soybean genistein in mice

This study was designed to probe the promoting effects of soybean soluble polysaccharide (SSPS) on bioavailability of genistein in mice and the underlying molecular mechanism. Male Kunming mice (n=8) were administered intragastrically with either saline, SSPS (5mg/kgbw), genistein (100mg/kgbw), or SSPS (5 or 50mg/kgbw) together with genistein (100mg/kgbw) for consecutive 28days. UPLC-qTOF/MS analysis showed that co-administration of SSPS and genistein in mice caused significant elevation in the urinary levels of genistein and its metabolites (p<0.05). Furthermore, the fecal excretion of genistein was also enhanced by co-administration of SSPS. However, the feces level of dihydrogenistein, a characteristic metabolite of genistein degraded by gut microorganism, was dose-dependently decreased by the combined treatment of SSPS. Additionally, co-treatment of SSPS with genistein also decreased the small intestinal levels of uridinediphosphate-glucuronosyltransferase (UGT), sulfotransferase (SULT), P-glycoprotein (P-gp), multidrug resistance-associated protein-1 (MRP1), and multidrug resistance-associated protein-2 (MRP2) in mice. These findings suggest that the inhibition of SSPS against small intestinal first-pass metabolism of genistein is involved in the promoting effect of genistein bioavailability in mice.

Non-digestible stachyose promotes bioavailability of genistein through inhibiting intestinal degradation and first-pass metabolism of genistein in mice

This study was designed to explore the molecular mechanism of stachyose in enhancing the gastrointestinal stability and absorption of soybean genistein in mice. Male Kunming mice in each group (n = 8) were administered by intragastric gavage with saline, stachyose (250 mg/kg·bw), genistein (100 mg/kg·bw), and stachyose (50, 250, and 500 mg/kg·bw) together with genistein (100 mg/kg·bw) for 4 consecutive weeks, respectively, and then their urine, feces, blood, gut, and liver were collected. UPLC-qTOF/MS analysis showed that levels of genistein and its metabolites (dihydrogenistein, genistein 7-sulfate sodium salt, genistein 4'-β-D-glucuronide, and genistein 7-β-D-glucuronide) in serum and urine were increased with an increase in stachyose dosages in mice. Furthermore, the feces level of genistein aglycone was also elevated by co-treatment of stachyose with genistein. However, the feces concentration of dihydrogenistein, a characteristic metabolite of genistein by gut microorganism, was decreased by stachyose administration in a dose-dependent manner. Additionally, the simultaneous administration with stachyose and genistein in mice could decrease intestinal SULT, UGT, P-gp, and MRP1 expression, relative to the treatment with individual stachyose or genistein. These results demonstrate that stachyose-mediated inhibition against the intestinal degradation of genistein and expression of phase II enzymes and efflux transporters can largely contribute to the elevated bioavailability of soybean genistein.

The Prolyl Isomerase Pin1 Is a Novel Target of 6,7,4'-Trihydroxyisoflavone for Suppressing Esophageal Cancer Growth

Intake of soy isoflavones is inversely associated with the risk of esophageal cancer. Numerous experimental results have supported the anticancer activity of soy isoflavones. This study aimed to determine the anti-esophageal cancer activity of 6,7,4'-trihydroxyisoflavone (6,7,4'-THIF), a major metabolite of daidzein, which is readily metabolized in the human body. Notably, 6,7,4'-THIF inhibited proliferation and increased apoptosis of esophageal cancer cells. On the basis of a virtual screening analysis, Pin1 was identified as a target protein of 6,7,4'-THIF. Pull-down assay results using 6,7,4'-THIF Sepharose 4B beads showed a direct interaction between 6,7,4'-THIF and the Pin1 protein. Pin1 is a critical therapeutic and preventive target in esophageal cancer because of its positive regulation of β-catenin and cyclin D1. The 6,7,4'-THIF compound simultaneously reduced Pin1 isomerase activity and the downstream activation targets of Pin1. The specific inhibitory activity of 6,7,4'-THIF was analyzed using Neu/Pin1 wild-type (WT) and Neu/Pin1 knockout (KO) MEFs. 6,7,4'-THIF effected Neu/Pin1 WT MEFs, but not Neu/Pin1 KO MEFs. Furthermore, the results of a xenograft assay using Neu/Pin1 WT and KO MEFs were similar to those obtained from the in vitro assay. Overall, we found that 6,7,4'-THIF specifically reduced Pin1 activity in esophageal cancer models. Importantly, 6,7,4'-THIF directly bound to Pin1 but not FKBP or cyclophilin A, the same family of proteins. Because Pin1 acts like an oncogene by modulating various carcinogenesis-related proteins, this study might at least partially explain the underlying mechanism(s) of the anti-esophageal cancer effects of soy isoflavones. Cancer Prev Res; 10(5); 308-18. ©2017 AACR.

Antiadipogenic Effects and Mechanisms of Combinations of Genistein, Epigallocatechin-3-Gallate, and/or Resveratrol in Preadipocytes

Natural bioactive compounds are considered an excellent alternative strategy for developing effective, safe, and cost-effective antiobesity agents. The aim of this study was to investigate if combinations of soy bean genistein (G), green tea epigallocatechin-3-gallate (E), and/or grape resveratrol (R) at low dosages synergistically inhibit preadipocyte differentiation both in 3T3-L1 cells and human primary preadipocytes (HPAs). Our results show that combinations of G, E, and/or R additively inhibited preadipocyte differentiation (39-56% of control) both in 3T3-L1 cells at 30 μM and HPAs at 15 μM, while the individual compounds have no antiadipogenic effect at the selected concentrations. We also observed similar patterns that combinations of G, E, and/or R additively reduced protein expressions of peroxisome proliferator-activated receptor gamma (PPAR-γ) and CCAAT binding proteins alpha (C/EBP-α), the two key preadipocyte differentiation regulators, both in differentiated 3T3-L1 cells and HPAs. Moreover, combined G, E, and/or R attenuated protein expressions of fatty acid binding protein 4 and perilipin, two PPAR-γ/C/EBP-α downstream molecules in fat drop development in a very similar pattern, in inhibiting differentiation in preadipocytes. This combined antiadipogenic effect of G + E + R is additive, not synergistic according to our results and the Median-Effect Principle. In addition, we found that a lower concentration (15 μM) of G, E, and/or R is required in HPAs than the concentration (30 μM) needed in 3T3-L1 cells, to exert the combined antiadipogenic effect. These data suggest that combinations of G, E, and/or R intake or soy bean, green tea, and/or grape simultaneous consumption may prevent obesity in human being.

Estrogen receptor-α and aryl hydrocarbon receptor involvement in the actions of botanical estrogens in target cells

Botanical estrogen (BE) dietary supplements are consumed by women as substitutes for loss of endogenous estrogens at menopause. To examine the roles of estrogen receptor α (ERα) and aryl hydrocarbon receptor (AhR) and their crosstalk in the actions of BEs, we studied gene regulation and proliferation responses to four widely used BEs, genistein, daidzein, and S-equol from soy, and liquiritigen from licorice root in breast cancer and liver cells. BEs and estradiol (E2), acting through ERα, stimulated proliferation, ERα chromatin binding and target-gene expression. BEs but not E2, acting through AhR, bound to xenobiotic response element-containing chromatin sites and enhanced AhR target-gene expression (CYP1A1, CYP1B1). While E2 and TCDD acted quite selectively through their respective receptors, BEs acted via both receptors, with their AhR activity moderated by negative crosstalk through ERα. Both ERα and AhR should be considered as mediators of the biology and pharmacology of BEs.

Protective Effect of Genistein against Neuronal Degeneration in ApoE-/- Mice Fed a High-Fat Diet

Altered cholesterol metabolism is believed to play a causal role in major pathophysiological changes in neurodegeneration. Several studies have demonstrated that the absence of apolipoprotein E (ApoE), a predominant apolipoprotein in the brain, leads to an increased susceptibility to neurodegeneration. Previously, we observed that genistein, a soy isoflavone, significantly alleviated apoptosis and tau hyperphosphorylation in SH-SY5Y cells. Therefore, we investigated the neuroprotective effects of dietary genistein supplementation (0.5 g/kg diet) in the cortex and hippocampus of wild-type C57BL/6 (WT) and ApoE knockout (ApoE^−/−) mice fed a high-fat diet (HFD) for 24 weeks. Genistein supplementation alleviated neuroinflammation and peripheral and brain insulin resistance. Reductions in oxidative and endoplasmic reticulum stress were also observed in ApoE^−/− mice fed a genistein-supplemented diet. Beta-secretase 1 and presenilin 1 mRNA levels and beta-amyloid peptide (Aβ) protein levels were reduced in response to genistein supplementation in ApoE^−/− mice but not in WT mice. Although the absence of ApoE did not increase tau hyperphosphorylation, genistein supplementation reduced tau hyperphosphorylation in both WT and ApoE^−/− mice. Consistent with this result, we also observed that genistein alleviated activity of c-Jun N-terminal kinase and glycogen synthase kinase 3β, which are involved in tau hyperphosphorylation. Taken together, these results demonstrate that genistein alleviated neuroinflammation, Aβ deposition, and hyperphosphorylation in ApoE^−/− mice fed an HFD.

Effects of stachyose on absorption and transportation of tea catechins in mice: possible role of Phase II metabolic enzymes and efflux transporters inhibition by stachyose

Background

Nutritional and absorption-promoting properties of stachyose combined with tea catechins (TC) have been revealed. However, the mechanism involved in non-digestible oligosaccharides-mediated enhancement of flavonoid absorption has largely remained elusive.

Methods

This study was designed to investigate the molecular mechanism of stachyose in enhancing absorption and transportation of TC in mice. Mice were orally pre-treated with stachyose (50, 250, and 500 mg/kg·bw) for 0–8 weeks, and 1 h before sacrifice, mice were treated with TC (250 mg/kg·bw).

Results

Gas chromatography-mass spectrometry analysis showed that serum concentrations of epicatechin, epigallocatechin, epicatechin gallate, and epigallocatechin gallate were dose- and time-dependently elevated with stachyose pre-treatment in mice. Furthermore, pre-treatment with stachyose in mice reduced intestinal sulfotransferase and uridine diphosphate-glucuronosyltransferase levels by 3.3–43.2% and 23.9–30.4%, relative to control mice, respectively. Moreover, intestinal P-glycoprotein and multidrug resistance-associated protein-1 contents were decreased in mice by pre-administration of stachyose in dose- and time-dependent manner.

Conclusions

This is the first time to demonstrate that suppression of Phase II metabolic enzymes and efflux transporters of TC in the intestine can play a major role in increasing absorption of TC by stachyose feeding.

Phytoestrogen Metabolism by Adult Human Gut Microbiota

Phytoestrogens are plant-derived polyphenols with a structure similar to human estrogens. The three main groups of phytoestrogens, isoflavones, ellagitannins, and lignans, are transformed into equol, urolithins, and enterolignans, respectively, by bacteria. These metabolites have more estrogenic/antiestrogenic and antioxidant activities than their precursors, and they are more bioavailable. The aim of this study was to analyze the metabolism of isoflavones, lignans and ellagitannins by gut microbiota, and to study the possible correlation in the metabolism of these three groups of phytoestrogens. In vitro fermentation experiments were performed with feces samples from 14 healthy adult volunteers, and metabolite formation was measured by HPLC-PAD and HPLC-ESI/MS. Only the microbiota of one subject produced equol, while most of them showed production of O-desmethylangolensin (O-DMA). Significant inter-subject differences were observed in the metabolism of dihydrodaidzein and dihydrogenistein, while the glucoside isoflavones and their aglycones showed less variability, except for glycitin. Most subjects produced urolithins M-5 and E. Urolithin D was not detected, while uroltithin B was found in half of the individuals analyzed, and urolithins A and C were detected in two and four subjects, respectively. Enterolactone was found in all subjects, while enterodiol only appeared in five. Isoflavone metabolism could be correlated with the metabolism of lignans and ellagitannins. However, the metabolism of ellagitannins and lignans could not be correlated. This the first study where the metabolism of the three groups together of phytoestrogen, isoflavones, lignans, and ellagitannins by gut microbiota is analyzed.

The combined effects of soya isoflavones and resistant starch on equol production and trabecular bone loss in ovariectomised mice

Equol is a metabolite of the soya isoflavone (ISO) daidzein that is produced by intestinal microbiota. Equol has greater oestrogenic activity compared with other ISO, and it prevents bone loss in postmenopausal women. Resistant starch (RS), which has a prebiotic activity and is a dietary fibre, was reported to promote equol production. Conversely, the intestinal microbiota is reported to directly regulate bone health by reducing inflammatory cytokine levels and T-lymphocytes in bone. The present study evaluated the combined effects of diet supplemented with ISO and RS on intestinal microbiota, equol production, bone mineral density (BMD) and inflammatory gene expression in the bone marrow of ovariectomised (OVX) mice. Female ddY strain mice, aged 8 weeks, were either sham-operated (Sham, n 7) or OVX. OVX mice were randomly divided into the following four groups (seven per group): OVX control (OVX); OVX fed 0·05 % ISO diet (OVX+ISO); OVX fed 9 % RS diet (OVX+RS); and OVX fed 0·05 % ISO- and 9 % RS diet (OVX+ISO+RS). After 6 weeks, treatment with the combination of ISO and RS increased equol production, prevented the OVX-induced decline in trabecular BMD in the distal femur by modulating the enteric environment and altered OVX-induced inflammation-related gene expression in the bone marrow. However, there were no significant differences in bone parameters between the ISO+RS and ISO-alone groups in OVX mice. Our findings suggest that the combination of ISO and RS might alter intestinal microbiota and immune status in the bone marrow, resulting in attenuated bone resorption in OVX mice.

Investigation of the interactions between Chrysanthemum morifolium flowers extract and intestinal bacteria from human and rat

Flos Chrysanthemi, dried flower of Chrysanthemum morifolium Ramat, has drawn much attention recently owing to its potential beneficial health effects for human. Flos Chrysanthemi products are usually taken orally and metabolized by intestinal microflora. However, there has been no investigation of the comprehensive metabolic profile of the Flos Chrysanthemi extract by intestinal flora owing to its chemical complexity and the limitations of analytical methods. In this paper, a rapid, sensitive and automated analysis method, ultra-performance liquid chromatography/quadrupole time of flight mass spectrometry including MS^E technology and automated data processing Metabolynx™ software, was developed and successfully applied for the biotransformation and metabolic profile of flavonoids in the Flos Chrysanthemi extract by intestinal flora from human and rat. A total of 32 metabolites were detected and tentatively identified in human and rat intestinal bacterial samples. These metabolites indicated that hydrolysis, hydroxylation, acetylation, methylation, hydrogenation and deoxygenation were the major conversion pathways of flavonoids in the Flos Chrysanthemi extract in vitro. Furthermore, the effects of the Flos Chrysanthemi extract on the growth of different intestinal bacteria were detected using an Emax precision microplate reader. Certain pathogenic bacteria such as Enterobacter, Enterococcus, Clostridium and Bacteroides were significantly inhibited by Flos Chrysanthemi, while commensal probiotics such as Lactobacillus and Bifidobacterium were moderately promoted. Our observation provided further evidence for the importance of intestinal bacteria in the metabolism and potential activity of the Flos Chrysanthemi extract. The results will also be helpful for the further pharmacokinetic study of Flos Chrysanthemi and to unravel how it works in vivo.

Alternaria toxins of the alternariol type are not metabolised by human faecal microbiota

The metabolism of the Alternaria toxins alternariol (AOH), alternariol-9-O-methyl ether (AME) and altenuene (ALT) by the microbiota present in faeces from three human volunteers was studied. Faecal cultures were prepared as a 5% faeces suspension in brain-heart infusion broth and incubated with 50 μM of the toxins under anaerobic conditions for 72 h at 37 °C. The metabolism of AOH was also studied in pure bacterial cultures with either Escherichia coli DH5α or Lactobacillus plantarum BFE 5092 for 72 h at 37 °C. The three parent toxins were stable in uninoculated, heat-treated medium over a 72 h incubation period with a recovery of more than 90%. As a control for the activity of the faecal microbiota, the isoflavone daidzein was incubated with the faecal cultures and was transformed to its expected metabolites. In contrast, no metabolites of AOH, AME and ALT could be detected in the faecal cultures from the same volunteers, indicating that the gut microbiota was not capable of metabolising these substances. The Alternaria toxins could be shown to be at least partially bound to bacterial cells in a non-covalent manner, which may serve as a mechanism for their removal from the gut.

Pharmacokinetic Comparison of Soy Isoflavone Extracts in Human Plasma

The soy isoflavones daidzein and genistein produce several biological activities related to health benefits. A number of isoflavone extracts are commercially available, but there is little information concerning the specific isoflavone content of these products or differences in their bioavailability and pharmacokinetics. This study describes the development and validation of an analytical method to detect and quantify daidzein, genistein, and equol in human plasma using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The method was applied in a crossover, randomized, bioavailability study. Twelve healthy volunteers were administered the same total isoflavones dose from two isoflavone supplement preparations (Super-Absorbable Soy Isoflavones (Life Extension, USA) and Fitoladius (Merck, Spain)). The pharmacokinetic parameters (AUC0-24/dose and Cmax/dose) of the isoflavones from the two preparations differed significantly. Such differences in bioavailability and kinetics may have relevant effects on the health benefits derived from their intake.

Epigenetic activities of flavonoids in the prevention and treatment of cancer

Aberrant epigenetic modifications are described in an increasing number of pathological conditions, including neurodegenerative diseases, cardiovascular diseases, diabetes mellitus type 2, obesity and cancer. The general reversibility of epigenetic changes makes them an attractive and promising target e.g. in the treatment of cancer. Thus, a growing number of epigenetically active compounds are currently tested in clinical trials for their therapeutic potential. Interestingly, many phytochemicals present in plant foods, particularly flavonoids, are suggested to be able to alter epigenetic cellular mechanisms. Flavonoids are natural phenol compounds that form a large group of secondary plant metabolites with interesting biological activities. They can be categorized into six major subclasses, which display diverse properties affecting the two best characterized epigenetic mechanisms: modulation of the DNA methylation status and histone acetylation. High dietary flavonoid intake has strongly been suggested to reduce the risk of numerous cancer entities in a large body of epidemiological studies. Established health-promoting effects of diets rich in fruit and vegetables are faced by efforts to use purified flavonoids as supplements or pharmaceuticals, whereupon data on the latter applications remain controversial. The purpose of this review is to give an overview of current research on flavonoids to further elucidate their potential in cancer prevention and therapy, thereby focusing on their distinct epigenetic activities.

Red clover isoflavone metabolite bioavailability is decreased after fructooligosaccharide supplementation

BACKGROUND

Red clover is an important source of isoflavones; which has been made commercially available as dietary supplements for the treatment of menopausal symptoms. Bioavailability and metabolism of these red clover isoflavones (RCI) have not been studied in detail. Fructooligosaccharides (FOS) stimulate the growth of intestinal bacteria and play an important role in the formation of certain isoflavone metabolites, such as equol and O-desmethylangolensin.

OBJECTIVE

To determine the bioavailability of RCI metabolites and analyse whether FOS supplementation could influence their bioavailability.

METHODS

Seventeen healthy adults were enrolled in the study carried out in two periods. In the first, compound bioavailability was determined after consumption of 80 mg of RCI (MF11RCE). In the second, a 6-day supplementation of 2×3000 mg/day of FOS was administered before isoflavone consumption.

RESULTS

Biochanin A and formononetin were rapidly absorbed and both reached maximum concentrations at an average of 5-7h. Demethylation was a major reaction in the metabolic pathway. Daidzein serum level peaked after about 12.6h. Supplementation with FOS led to a significant decrease in the bioavailability of daidzein, dihydroformononetin, dihydrogenistein and dihydrodaidzein. An increase in equol production was also observed which did not reach statistical significance (p>0.05).

CONCLUSION

This study is the first to provide detailed data on RCI bioavailability in humans and determine no influence of FOS yet a trend toward increased equol production. More research is warranted involving a greater sample size.

Isoflavones: chemistry, analysis, functions and effects on health and cancer

Isoflavones are phytoestrogens and natural plant compounds which are similar to 17-β-estradiol in chemical structure. It is known that they can act as estrogen agonists or antagonists, depending on endocrine estrogenic levels, but actions of isoflavones are rather complex due to large number of variables such as chemical structures and mechanisms. Some hypotheses on biological mechanisms have not satisfactorily been confirmed to date and human epidemiological and experimental studies have been relatively limited. Nevertheless, isoflavones and isoflavone rich foods have become a focus on interest due to positive health benefits on many diseases, especially prevention of hormone-related cancers, cardiovascular disease, osteoporosis, and adverse postmenopausal symptoms, and improvement of physiological condition such as maintaining cognitive function. This review provides an overview of chemistry, analytical techniques (focused on human biospecimens), functions including biological mechanisms, and effects of isoflavones, on the basis of the available meta-analysis and review articles and some original articles, on health and cancer.

Plasma isoflavones and risk of primary liver cancer in Japanese women and men with hepatitis virus infection: a nested case-control study

BACKGROUND

Evidence suggests that estrogen plays a preventive role in primary liver cancer development, and it might be thought that isoflavones, which are structurally similar to estrogens and bind to estrogen receptors, are associated with the risk of liver cancer. We investigated this suspected association by measuring plasma concentrations of isoflavones in a nested case-control study of a population-based prospective cohort in Japan.

METHODS

From 18,628 target participants ages 40 to 69 years who returned the baseline questionnaire and provided blood samples, we selected those with either hepatitis B or hepatitis C virus infection at baseline (n = 1,544). Among these, 90 (28 women and 62 men) were newly diagnosed with primary liver cancer from 1993 through 2006; they were matched with 175 controls (54 women and 121 men). Plasma concentrations of isoflavones (genistein, daidzein, glycitein, and equol) were measured using triple quadrupole tandem liquid chromatography-mass spectrometry. The ORs of liver cancer development based on plasma concentrations were estimated with a conditional logistic regression model.

RESULTS

Basically, distributions of plasma isoflavone concentrations did not differ between the cases and controls. No statistically significant associations of genistein, daidzein, glycitein, and equol with primary liver cancer risk were found in either women or men.

CONCLUSIONS

In middle-aged Japanese women and men with hepatitis virus infection, plasma isoflavones were unassociated with the occurrence of primary liver cancer.

IMPACT

The role of isoflavones in liver carcinogenesis merits further study using both biomarkers and data on dietary intake of isoflavones. Cancer Epidemiol Biomarkers Prev; 24(3); 532-7. ©2014 AACR.

A novel soybean (Glycine max) gene encoding a family 3 β-glucosidase has high isoflavone 7-O-glucoside-hydrolyzing activity in transgenic rice

A previous study demonstrated that purified Glycine max β-glucosidase (GmBGL) could hydrolyze glucosyl isoflavone to the aglyconic form. This study reports the cloning and functional characterization of a soybean cDNA encoding the β-glucosidase. GmBGL was isolated by use of a purified soybean N-terminal amino acid sequence and conserved sequences of β-glucosidase genes from other plants. Sequence analysis of GmBGL revealed an open reading frame of 1884 bp encoding a polypeptide of 627 amino acids with a calculated molecular mass of 69 kDa. Phylogenetic analysis classified the GmBGL into the glycosyl hydrolase 3 family. In soybean, the GmBGL transcript was predominantly accumulated in roots and leaves. To examine the enzymatic activity and substrate specificity, GmBGL was ectopically expressed in transgenic rice. Purified GmBGL protein from transgenic rice could catalyze the hydrolysis of genistin and daidzin to produce genistein and daidzein, respectively, which confirmed GmBGL as a functional β-glucosidase with isoflavone glucoside-hydrolyzing activity. This paper reveals that GmBGL is a key enzyme in transforming glucosyl isoflavones to aglycones in soybean, which may help in genetic manipulation of aglycone-rich soybean seeds.

Plasma bioavailability and changes in PBMC gene expression after treatment of ovariectomized rats with a commercial soy supplement

The health effects of soy supplementation in (post)menopausal women are still a controversial issue. The aim of the present study was to establish the effect of the soy isoflavones (SIF) present in a commercially available supplement on ovariectomized rats and to investigate whether these rats would provide an adequate model to predict effects of SIF in (post)menopausal women. Two dose levels (i.e. 2 and 20 mg/kg b.w.) were used to characterize plasma bioavailability, urinary and fecal concentrations of SIF and changes in gene expression in peripheral blood mononuclear cells (PBMC). Animals were dosed at 0 and 48 h and sacrificed 4 h after the last dose. A clear dose dependent increase of SIF concentrations in plasma, urine and feces was observed, together with a strong correlation in changes in gene expression between the two dose groups. All estrogen responsive genes and related biological pathways (BPs) that were affected by the SIF treatment were regulated in both dose groups in the same direction and indicate beneficial effects. However, in general no correlation was found between the changes in gene expression in rat PBMC with those in PBMC of (post)menopausal women exposed to a comparable dose of the same supplement. The outcome of this short-term study in rats indicates that the rat might not be a suitable model to predict effects of SIF in humans. Although the relative exposure period in this rat study is comparable with that of the human study, longer repetitive administration of rats to SIF may be required to draw a final conclusion on the suitability of the rat a model to predict effects of SIF in humans.