Isoflavone metabolism and bone-sparing effects of daidzein-metabolites

Unveiling the neuroprotective properties of isoflavones: current evidence, molecular mechanisms and future perspectives

Neurodegenerative diseases encompass a wide range of debilitating and incurable brain disorders characterized by the progressive deterioration of the nervous system's structure and function. Isoflavones, which are naturally occurring polyphenolic phytochemicals, have been found to regulate various cellular signaling pathways associated with the nervous system. The main objective of this comprehensive review is to explore the neuroprotective effects of isoflavones, elucidate the underlying mechanisms, and assess their potential for treating neurodegenerative disorders. Relevant data regarding isoflavones and their impact on neurodegenerative diseases were gathered from multiple library databases and electronic sources, including PubMed, Google Scholar, Web of Science, and Science Direct. Numerous isoflavones, including genistein, daidzein, biochanin A, and formononetin, have exhibited potent neuroprotective properties against various neurodegenerative diseases. These compounds have been found to modulate neurotransmitters, which in turn contributes to their ability to protect against neurodegeneration. Both in vitro and in vivo experimental studies have provided evidence of their neuroprotection mechanisms, which involve interactions with estrogenic receptors, antioxidant effects, anti-inflammatory properties, anti-apoptotic activity, and modulation of neural plasticity. This review aims to provide current insights into the neuroprotective characteristics of isoflavones and shed light on their potential therapeutic applications in future clinical scenarios.

A mixture of Pueraria lobata and Platycodon grandiflorum extracts ameliorates RANKL-induced osteoclast differentiation and ovariectomy-induced bone loss by regulating Src- PI3K-AKT and JNK/p38 signaling pathways

Osteoporosis is caused by increased bone resorption due to the excessive activity of osteoclasts. Pueraria lobata has demonstrated the ability to improve bone density in ovariectomized mice, and Platycodon grandiflorum can suppress osteolysis biomarkers such as collagen content in cartilage and alkaline phosphatase activity. In this study, we examined whether HX112, a mixture of Pueraria lobata and Platycodon grandiflorum extracts, could inhibit the receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL)-induced osteoclast differentiation to alleviate osteoporosis. To induce the differentiation of osteoclasts, RAW 264.7 cell were cultured with RANKL and HX112. Osteoclasts differentiation was evaluated by TRAP activity and TRAP staining. Bone resorption as osteoclasts major function was assessed by pit formation assay. As a result, HX112 suppressed osteoclast differentiation and bone resorptive function. Additionally, HX112 reduced the expression of osteoclastogenic genes including NFATc1 and c-Fos, and these effects of HX112 were mediated by inhibiting Src-phosphoinositide 3-kinase (PI3K)- Protein kinase B (Akt) and c-Jun N-terminal kinase (JNK)/p38 signaling pathways. Furthermore, ICR mice were ovariectomized to induce osteoporosis and bone mineral density of femur was measured using micro-CT. Consequently, oral administration of HX112 to ovariectomized mice significantly improved bone microstructure and bone mineral density. Collectively, these findings indicate that the mixed extract of Pueraria lobata and Platycodon grandiflorum may be useful as therapeutics for osteoporosis.

Biotransformation of Natural Products and Phytochemicals: Metabolites, Their Preparation, and Properties

The term "biotransformation" refers to the process by which various compounds are biocatalyzed and enzymatically modified, as well as the metabolic changes that occur in organisms as a result of exposure to xenobiotics [...].

Advancements in lead therapeutic phytochemicals polycystic ovary syndrome: A review

Polycystic ovary syndrome (PCOS) is one of the most common endocrine diseases in women of reproductive age and features complex pathological symptoms and mechanisms. Existing medical treatments have, to some extent, alleviated the deterioration of PCOS. However, these strategies only temporarily control symptoms, with a few side effects and no preventive effect. Phytochemicals extracted from medicinal herbs and plants are vital for discovering novel drugs. In recent years, many kinds of research have proven that phytochemicals isolated from traditional Chinese medicine (TCM) and medicinal plants show significant potential in preventing, alleviating, and treating PCOS. Nevertheless, compared to the abundance of experimental literature and minimal specific-topic reviews related to PCOS, there is a lack of systematic reviews to summarize these advancements in this promising field. Under this background, we systematically document the progress of bioactive phytochemicals from TCM and medicinal plants in treating PCOS, including flavonoids, polyphenols, and alkaloids. According to the literature, these valuable phytochemicals demonstrated therapeutic effects on PCOS supported by in vivo and in vitro experiments, mainly depending on anti-inflammatory, antioxidation, improvement of hormone disorder and insulin resistance (IR), and alleviation of hyperinsulinemia. Based on the current progress, future research directions should emphasize 1) exploring bioactive phytochemicals that potentially mediate bone metabolism for the treatment of PCOS; 2) improving unsatisfactory bioavailability by using advanced drug delivery systems such as nanoparticles and antibody-conjugated drugs, as well as a chemical modification; 3) conducting in-depth research on the pathogenesis of PCOS to potentially impact the gut microbiota and its metabolites in the evolution of PCOS; 4) revealing the pharmacological effects of these bioactive phytochemicals on PCOS at the genetic level; and 5) exploring the hypothetical and unprecedented functions in regulating PCOS by serving as proteolysis-targeting chimeras and molecular glues compared with traditional small molecule drugs. In brief, this review aims to provide detailed mechanisms of these bioactive phytochemicals and hopefully practical and reliable insight into clinical applications concerning PCOS.

Equol exerts a protective effect on postmenopausal osteoporosis by upregulating OPG/RANKL pathway

BACKGROUD

Estrogen deficiency is the leading cause of postmenopausal osteoporosis(PMOP) and phytoestrogens soy isoflavones (SI) have been shown to improve PMOP. Equol (Eq), an in vivo metabolite of phytoestrogens soy isoflavones (SI), has a more stable structure and stronger biological activity than its parent compound and has the greatest estrogenic activity. However, there are few studies on the therapeutic effect of Eq on PMOP.

PURPOSE

To explore the therapeutic effect and mechanisms of Eq on POMP.

METHODS

Osteoblast-like cells ROS1728 were cultured with different doses of Eq, estradiol (E2), separately. The effect of Eq on the proliferation, apoptosis, cell cycle of osteoblasts were detected by CCK-8 and flow cytometry, and the expression of OPG/RANK/RANKL signaling pathway of osteoblasts was detected by Quantitative real-time PCR (qRT-PCR) and Western blot (WB), and RNA silencing technology were carried out to explore the receptors through which Eq plays a role. Then PMOP rat model was established and treated by Eq or E2 to further verification of the effect and mechanism of Eq on PMOP.

RESULT

Eq promoted the proliferation and inhibited the apoptosis of osteoblasts and increased the proportion of osteoblasts in the S phase and G2/M phase in a dose-dependent manner. Mechanistically, Eq treatment upregulated the expression of OPG and OPG/RANKL ratio in osteoblasts and this regulatory effect was mainly mediated through the ERβ receptor. Furthermore, in vivo study, Eq improved microstructure and BMD of the femur of PMOP rat model, which imitated the osteoprotective effect of E2. Moreover, the Eq or E2 treatment increased serum levels of Ca, 1,25(OH)2D3, bone Gla-protein(BGP), and Type I procollagen (PC1), and reduced serum levels of phosphorus (P), parathyroid hormone(PTH), pyridinol (PYD), tartrate-resistant acid phosphatase (TRAP) and urinary level of deoxypyridinoline (DPD) in the treatment OVX group compared with the untreated OVX group. Meanwhile, Eq or E2 markedly induced the mRNA and protein expression of OPG and OPG/RANKL ratio.

CONCLUSION

Eq can combine with ERβ and exert a protective effect on PMOP by upregulating OPG/RANKL pathway.

Deep Learning-Assisted Repurposing of Plant Compounds for Treating Vascular Calcification: An In Silico Study with Experimental Validation

Background

Vascular calcification (VC) constitutes subclinical vascular burden and increases cardiovascular mortality. Effective therapeutics for VC remains to be procured. We aimed to use a deep learning-based strategy to screen and uncover plant compounds that potentially can be repurposed for managing VC.

Methods

We integrated drugome, interactome, and diseasome information from Comparative Toxicogenomic Database (CTD), DrugBank, PubChem, Gene Ontology (GO), and BioGrid to analyze drug-disease associations. A deep representation learning was done using a high-level description of the local network architecture and features of the entities, followed by learning the global embeddings of nodes derived from a heterogeneous network using the graph neural network architecture and a random forest classifier established for prediction. Predicted results were tested in an in vitro VC model for validity based on the probability scores.

Results

We collected 6,790 compounds with available Simplified Molecular-Input Line-Entry System (SMILES) data, 11,958 GO terms, 7,238 diseases, and 25,482 proteins, followed by local embedding vectors using an end-to-end transformer network and a node2vec algorithm and global embedding vectors learned from heterogeneous network via the graph neural network. Our algorithm conferred a good distinction between potential compounds, presenting as higher prediction scores for the compound categories with a higher potential but lower scores for other categories. Probability score-dependent selection revealed that antioxidants such as sulforaphane and daidzein were potentially effective compounds against VC, while catechin had low probability. All three compounds were validated in vitro.

Conclusions

Our findings exemplify the utility of deep learning in identifying promising VC-treating plant compounds. Our model can be a quick and comprehensive computational screening tool to assist in the early drug discovery process.

A Citrus Fruit Extract High in Polyphenols Beneficially Modulates the Gut Microbiota of Healthy Human Volunteers in a Validated In Vitro Model of the Colon

The effect of a Citrus Fruit Extract high in the polyphenols hesperidin and naringin (CFE) on modulation of the composition and activity of the gut microbiota was tested in a validated, dynamic in vitro model of the colon (TIM-2). CFE was provided at two doses (250 and 350 mg/day) for 3 days. CFE led to a dose-dependent increase in Roseburia, Eubacterium ramulus, and Bacteroides eggerthii. There was a shift in production of short-chain fatty acids, where acetate production increased on CFE, while butyrate decreased. In overweight and obesity, acetate has been shown to increase fat oxidation when produced in the distal gut, and stimulate secretion of appetite-suppressive neuropeptides. Thus, the data in the in vitro model point towards mechanisms underlying the effects of the polyphenols in CFE with respect to modulation of the gut microbiota, both in composition and activity. These results should be confirmed in a clinical trial.

EFFECT OF PUERARIN ON THE PROLIFERATION AND DIFFERENTIATION OF OSTEOBLASTS AND THE EXPRESSION OF TYPE I COLLAGEN mRNA IN A HIGH-GLUCOSE ENVIRONMENT

OBJECTIVE

To investigate the effect of puerarin (Pue) on the proliferation and differentiation of osteoblasts and the expression of type I collagen(Coll I) mRNA in a high-glucose (HG) environment, and to provide evidence for the clinical treatment of diabetic osteoporosis(DOP).

SUBJECTS AND METHODS

The proliferation of osteoblasts from three groups - the control group, the HS group, and the HG+Pue (10^-8-10^-6 M) group - was cultivated for 72 h and evaluated using the methyl thiazolyltetrazolium (MTT) assay.

RESULTS

The MTT values and the ALP activities in all experimental groups were significantly lower than those in the control group, and the MTT values and the ALP activities in the HG+Pue group were significantly higher than those in the HS group. Coll I mRNA expression in all experimental groups was significantly lower than that in the control group, while that in the HG+Pue group was significantly higher than that in the HG group.

CONCLUSIONS

The proliferation and differentiation of osteoblasts and the expression of Coll I mRNA were inhibited by high glucose, but Pue can increase the proliferation and differentiation as well as the expression of Coll I mRNA in the osteoblasts, indicating that Pue could be therapeutically beneficial against DOP.

The Effects of Trifolium pratense L. Sprouts' Phenolic Compounds on Cell Growth and Migration of MDA-MB-231, MCF-7 and HUVEC Cells

Uncontrolled growth and migration and invasion abilities are common for cancer cells in malignant tumors with low therapeutic effectiveness and high mortality and morbidity. Estrogen receptor β (ERβ), as a member of the nuclear receptor superfamily, shows potent tumor suppressive activities in many cancers. Phytoestrogens’ structural resemblance to 17 β-estradiol allows their binding to ERβ isoform predominantly, and therefore, expression of genes connected with elevated proliferation, motility and invasiveness of cancer cells may be downregulated. Among polyphenolic compounds with phytoestrogenic activity, there are isoflavones from Trifolium pratense L. (red clover) sprouts, containing high amounts of formononetin and biochanin A and their glycosides. To determine the source of the most biologically active isoflavones, we obtained four extracts from sprouts before and after their lactic fermentation and/or β-glucosidase treatment. Our previous results of ITC (isothermal titration calorimetry) modelling and a docking simulation showed clover isoflavones’ affinity to ERβ binding, which may downregulate cancer cell proliferation and migration. Thus, the biological activity of T. pratense sprouts’ extracts was checked under in vitro conditions against highly invasive human breast cancer cell line MDA-MB-231 and non-invasive human breast cancer cell line MCF-7 cells. To compare extracts’ activities acquired for cancer cells with those activities against normal cells, as a third model we choose human umbilical vein endothelial cells (HUVEC), which, due to their migration abilities, are involved in blood vessel formation. Extracts obtained from fermented sprouts at IC₀ dosages were able to inhibit migration of breast cancer cells through their influence on intracellular ROS generation; membrane stiffening; adhesion; regulation of MMP-9, N-cadherin and E-cadherin at transcriptional level; or VEGF secretion. Simultaneously, isolated phenolics revealed no toxicity against normal HUVEC cells. In the manuscript, we proposed a preliminary mechanism accounting for the in vitro activity of Trifolium pratense L. isoflavones. In this manner, T. pratense sprouts, especially after their lactic fermentation, can be considered a potent source of biological active phytoestrogens and a dietary supplement with anti-cancer and anti-invasion properties.

Evaluation of Isoflavones as Bone Resorption Inhibitors upon Interactions with Receptor Activator of Nuclear Factor-κB Ligand (RANKL)

Receptor activator of nuclear factor-κB ligand (RANKL) is a cytokine responsible for bone resorption. It binds its receptor RANK, which activates osteoporosis. High levels of osteoprotegerin (OPG) competitively binding RANKL limit formation of ligand-receptor complexes and enable bone mass maintenance. The new approach to prevent osteoporosis is searching for therapeutics that can bind RANKL and support OPG function. The aim of the study was to verify the hypothesis that isoflavones can form complexes with RANKL limiting binding of the cytokine to its receptor. Interactions of five isoflavones with RANKL were investigated by isothermal titration calorimetry (ITC), by in silico docking simulation and on Saos-2 cells. Daidzein and biochanin A showed the highest affinity for RANKL. Among studied isoflavones coumestrol, formononetin and biochanin A showed the highest potential for Saos-2 mineralization and were able to regulate the expression of RANKL and OPG at the mRNA levels, as well as osteogenic differentiation markers: alkaline phosphatase (ALP), collagen type 1, and Runt-related transcription factor 2 (Runx2). Comparison of the osteogenic activities of isoflavones showed that the use of physicochemical techniques such as ITC or in silico docking are good tools for the initial selection of substances showing a specific bioactivity.

Health Promotion Effects of Soy Isoflavones

Soybeans contain several physiologically active ingredients, such as soy phytosterol, soyasaponin, soy protein, and lecithin, and are therefore expected to express the functionalities of said ingredients. Among them, soy isoflavones have been studied in recent years for their various functions, including their obesity-preventing effect, blood glucose level reducing effect, osteoporosis and breast cancer risk reduction, and anti-oxidative effect, and several health promoting effects and disease preventing effects are expected. For example, it has been determined that soy isoflavones reduce body and fat weight in experiments in which mice were fed a diet containing soy isoflavones in studies on anti-obesity. Epidemiologic studies with humans have also shown that women who consume more soybeans have lower BMI than those who consume less. We previously found that soy isoflavones may have anti-obesity effects in myoblasts through the activation of transcriptional coactivator PGC-1β, which increases energy expenditure. In recent studies, a decrease in blood glucose level due to soy isoflavone was seen in an experiment in which diabetic model mice were fed a diet containing soy isoflavone. It has also been suggested that soy isoflavone intake may increase bone mineral density in postmenopausal women and reduce the risk of breast cancer. This review focuses on the actions of soy isoflavones known to date, including their anti-obesity and anti-diabetic effects, bone loss preventing effects, and cancer risk reduction effects, and introduces reports on the health promotion and disease prevention effects of soy isoflavones.

Polyphenols and bioavailability: an update

Based on many cell culture, animal and human studies, it is well known that the most challenge issue for developing polyphenolics as chemoprevention or anti-diabtetic agents is the low oral bioavailability, which may be the major reason relating to its ambiguous therapeutic effects and large inter-individual variations in clinical trials. This review intends to highlight the unscientific evaluation on the basis of the published data regarding in vitro bioactivity of polyphenols, which may sometimes mislead the researchers and to conclude that: first, bio-accessibilities values obtained in the studies for polyphenols should be highly reconsidered in accordance with the abundant newly identified circulating and excreted metabolites, with a particular attention to colonic metabolic products which are obviously contributing much more than expected to their absorptions; second, it is phenolic metabolites, which are formed in the small intestine and hepatic cells,low molecular weight catabolic products of the colonic microflora to travel around the human body in the circulatory system or reach body tissues to elicit bioactive effects. It is concluded that better performed in vivo intervention and in vitro mechanistic studies are needed to fully understand how these molecules interact with human physiological and pathological processes.

Nutrikinetics of Isoflavone Metabolites After Fermented Soybean Product (Cheonggukjang) Ingestion in Ovariectomized Mice

SCOPE

Cheonggukjang (CGJ) is a soybean-based quick-fermented food popular in Korea that contains a variety of biologically active compounds including isoflavones and saponins. Isoflavone bioavailability may be important for the bone health of postmenopausal women; therefore, the aim of this study is to evaluate the influence of fermentation on the isoflavone metabolite nutrikinetic profile after single dose CGJ or unfermented soybean administration in ovariectomized (OVX) and sham mice.

METHODS AND RESULTS

We identify 34 isoflavone metabolites using UPLC-QTOF-MS and analyze their nutrikinetics at different time points (0.25, 0.5, 1, 2, 4, 8, 16, and 24 h) to understand their fermentation- and OVX-mediated time-dependent concentration changes. Nutrikinetics analysis shows that genistein, daidzein, genistein 4'-sulfate, dihydrodaidzein sulfate, equol 4'-sulfate, and equol-7-glucuronide are present at high concentrations in all groups based on area-under-the-curve analysis. OVX mice appear to show lower isoflavone bioavailability than mice in the sham group. CGJ enhances various isoflavone metabolite bioavailability including genistein, 3-hydroxygenistein, and equol 7-glucuronide, compared to the unfermented soybean-treated group. Among these metabolites, intact isoflavones, 3-hydroxygenistein, genistein 4'-sulfate, and equol 7-glucuronide promote osteoblastogenesis and inhibit osteoclast formation.

CONCLUSIONS

CGJ has good isoflavone bioavailability and may be beneficial for the bone health of postmenopausal women.

Intestinal microbiota: a potential target for the treatment of postmenopausal osteoporosis

Postmenopausal osteoporosis (PMO) is a prevalent metabolic bone disease characterized by bone loss and structural destruction, which increases the risk of fracture in postmenopausal women. Owing to the high morbidity and serious complications of PMO, many efforts have been devoted to its prophylaxis and treatment. The intestinal microbiota is the complex community of microorganisms colonizing the gastrointestinal tract. Probiotics, which are dietary or medical supplements consisting of beneficial intestinal bacteria, work in concert with endogenous intestinal microorganisms to maintain host health. Recent studies have revealed that bone loss in PMO is closely related to host immunity, which is influenced by the intestinal microbiota. The curative effects of probiotics on metabolic bone diseases have also been demonstrated. The effects of the intestinal microbiota on bone metabolism suggest a promising target for PMO management. This review seeks to summarize the critical effects of the intestinal microbiota and probiotics on PMO, with a focus on the molecular mechanisms underlying the pathogenic relationship between bacteria and host, and to define the possible treatment options.

Influence of Oral and Gut Microbiota in the Health of Menopausal Women

Sex differences in gut microbiota are acknowledged, and evidence suggests that gut microbiota may have a role in higher incidence and/or severity of autoimmune diseases in females. Additionally, it has been suggested that oral, vaginal, and gut microbiota composition can be regulated by estrogen levels. The association of vaginal microbiota with vulvovaginal atrophy at menopause is well described in the literature. However, the relevance of oral and gut microbiota modulation in the immune system during estrogen deficiency and its effect on inflammatory diseases is not well explored. Estrogen deficiency is a condition that occurs in menopausal women, and it can last approximately 30 years of a woman’s life. The purpose of this mini- review is to highlight the importance of alterations in the oral and gut microbiota during estrogen deficiency and their effect on oral and inflammatory diseases that are associated with menopause. Considering that hormone replacement therapy is not always recommended or sufficient to prevent or treat menopause-related disease, we will also discuss the use of probiotics and prebiotics as an option for the prevention or treatment of these diseases.

Polyphenols from Root, Tubercles and Grains Cropped in Brazil: Chemical and Nutritional Characterization and Their Effects on Human Health and Diseases

Throughout evolution, plants have developed the ability to produce secondary phenolic metabolites, which are important for their interactions with the environment, reproductive strategies and defense mechanisms. These (poly)phenolic compounds are a heterogeneous group of natural antioxidants found in vegetables, cereals and leguminous that exert beneficial and protective actions on human health, playing roles such as enzymatic reaction inhibitors and cofactors, toxic chemicals scavengers and biochemical reaction substrates, increasing the absorption of essential nutrients and selectively inhibiting deleterious intestinal bacteria. Polyphenols present in some commodity grains, such as soy and cocoa beans, as well as in other vegetables considered security foods for developing countries, including cassava, taro and beetroot, all of them cropped in Brazil, have been identified and quantified in order to point out their bioavailability and the adequate dietary intake to promote health. The effects of the flavonoid and non-flavonoid compounds present in these vegetables, their metabolism and their effects on preventing chronic and degenerative disorders like cancers, diabetes, osteoporosis, cardiovascular and neurological diseases are herein discussed based on recent epidemiological studies.

Equol, a Dietary Daidzein Gut Metabolite Attenuates Microglial Activation and Potentiates Neuroprotection In Vitro

Estrogen deficiency has been well characterized in inflammatory disorders including neuroinflammation. Daidzein, a dietary alternative phytoestrogen found in soy (Glycine max) as primary isoflavones, possess anti-inflammatory activity, but the effect of its active metabolite Equol (7-hydroxy-3-(4′-hydroxyphenyl)-chroman) has not been well established. In this study, we investigated the anti-neuroinflammatory and neuroprotective effect of Equol in vitro. To evaluate the potential effects of Equol, three major types of central nervous system (CNS) cells, including microglia (BV-2), astrocytes (C6), and neurons (N2a), were used. Effects of Equol on the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase (COX-2), Mitogen activated protein kinase (MAPK) signaling proteins, and apoptosis-related proteins were measured by western blot analysis. Equol inhibited the lipopolysaccharide (LPS)-induced TLR4 activation, MAPK activation, NF-kB-mediated transcription of inflammatory mediators, production of nitric oxide (NO), release of prostaglandin E2 (PGE-2), secretion of tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6), in Lipopolysaccharide (LPS)-activated murine microglia cells. Additionally, Equol protects neurons from neuroinflammatory injury mediated by LPS-activated microglia through downregulation of neuronal apoptosis, increased neurite outgrowth in N2a cell and neurotrophins like nerve growth factor (NGF) production through astrocytes further supporting its neuroprotective potential. These findings provide novel insight into the anti-neuroinflammatory effects of Equol on microglial cells, which may have clinical significance in cases of neurodegeneration.

Long-term kinetics of daidzein and its main metabolites in human equol-producers after soymilk intake: identification of equol-conjugates by UPLC-orbitrap-MS and influence of the number of transforming bacteria on plasma kinetics

The main aim of the study was to establish in vivo a correlation between equol (EQU) production and a number of intestinal bacteria able to perform the transformation. Thus, healthy female volunteers were selected for their ability to convert slowly (n = 6, 10⁵-10⁹ cells/g wet feces) or quickly (n = 6, 10¹⁰-10¹² cells/g wet feces) daidzein (DAI) in EQU. After oral administration of 100 mg DAI in soymilk, plasma (0-99 h) and urine (0-96 h) samples were collected. DAI and its metabolites were determined by LC-MS/MS and EQU -conjugates by UPLC-High Resolution-MS. Only for EQU a direct correlation was found between the number of transforming microorganisms and parameters such as t_max and t_1/2 (p = 0.027). Peak serum concentration time, C_max, AUC_0-72 h and t_1/2 for total EQU (n = 12) were 36 ± 10 h, 89 ± 78 nM, 2.4 ± 1.7 (μmol × h/L) and 15.6 ± 3.3 h, respectively. In plasma and urine EQU was found mainly as 7-O-glucuronide.

A combination of soy isoflavones and cello-oligosaccharides changes equol/O-desmethylangolensin production ratio and attenuates bone fragility in ovariectomized mice

We examined the cooperative effects of isoflavones and cello-oligosaccharides on daidzein metabolism and bone fragility in ovariectomized mice. Cello-oligosaccharides increased urinary equol and decreased O-desmethylangolensin. A combination of isoflavones and cello-oligosaccharides attenuated decreases in bone breaking force and stiffness caused by ovariectomy. Combination treatment with isofalvones and cello-oligosaccharides increases urinary equol/O-desmethylangolensin production ratio and prevents ovariectomy-induced abnormalities in bone strength.

The role of colonic bacteria in the metabolism of the natural isoflavone daidzin to equol

Isoflavones are found in leguminous plants, especially soybeans. They have a structural similarity to natural estrogens, which enables them to bind to estrogen receptors and elicit biological activities similar to natural estrogens. They have been suggested to be beneficial for the prevention and therapy of hormone-dependent diseases. After soy products are consumed, the bacteria of the intestinal microflora metabolize isoflavones to metabolites with altered absorption, bioavailability, and estrogenic characteristics. Variations in the effect of soy products have been correlated with the isoflavone metabolites found in plasma and urine samples of the individuals consuming soy products. The beneficial effects of the soy isoflavone daidzin, the glycoside of daidzein, have been reported in individuals producing equol, a reduction product of daidzein produced by specific colonic bacteria in individuals called equol producers. These individuals comprise 30% and 60% of populations consuming Western and soy-rich Asian diets, respectively. Since the higher percentage of equol producers in populations consuming soy-rich diets is correlated with a lower incidence of hormone-dependent diseases, considerable efforts have been made to detect the specific colonic bacteria involved in the metabolism of daidzein to the more estrogenic compound, equol, which should facilitate the investigation of the metabolic activities related to this compound.

R(-)-O-desmethylangolensin is the main enantiomeric form of daidzein metabolite produced by human in vitro and in vivo

After ingestion, human intestinal bacteria transform daidzein into dihydrodaidzein, which can be further metabolised to O-desmethylangolensin. This metabolite, unlike daidzein, has a chiral centre and can therefore occur as two distinct enantiomers; however, it is unclear which enantiomer is present in humans. The aim of this study was to define in vitro and in vivo the structure of O-desmethylangolensin and then to evaluate its pharmacokinetic parameters. Daidzein metabolism was preliminarily investigated in anaerobic batch cultures inoculated with mixed faecal bacteria from O-desmethylangolensin producer volunteers. The transformation was monitored by liquid chromatography-mass spectrometry and a chiral column was used to distinguish dihydrodaidzein and O-desmethylangolensin enantiomers. These were purified, analysed by circular dichroism and the results established R(-)-O-desmethylangolensin as the main product (enantiomer excess 91%). However, both dihydrodaidzein enantiomers were detected. Similar results were obtained by in vivo trials. The in vitro formation of O-desmethylangolensin seems to be directly correlated with the number of transforming microorganisms. This correlation was found in vivo for tmax but not for other pharmacokinetic indexes. The pharmacokinetics of daidzein, dihydrodaidzein and O-desmethylangolensin were then evaluated in 11 healthy adult O-desmethylangolensin producers after the single administration of soy milk containing 100mg daidzein. The conjugated forms of daidzein, dihydrodaidzein and O-desmethylangolensin represent more than 90 and 95% of the plasmatic and urinary forms, respectively. The Cmax, tmax and half-life of O-desmethylangolensin in plasma were 62±53nM, 28±11 and 15±6h, respectively. Relevant inter-individual variations were observed as indicated by the high standard deviations.