Showing papers on "Isoflavones published in 2013"
TL;DR: The evaluation of isoflavone metabolism and bioavailability is crucial to understanding their biological effects and Lipid-based formulations such as drug incorporation into oils, emulsions and self-microemulsifying formulations have been introduced to increase bioavailability.
Abstract: Isoflavones are phytoestrogens with potent estrogenic activity; genistein, daidzein and glycitein are the most active isoflavones found in soy beans. Phytoestrogens have similarity in structure with the human female hormone 17-β-estradiol, which can bind to both alpha and beta estrogen receptors, and mimic the action of estrogens on target organs, thereby exerting many health benefits when used in some hormone-dependent diseases. Numerous clinical studies claim benefits of genistein and daidzein in chemoprevention of breast and prostate cancer, cardiovascular disease and osteoporosis as well as in relieving postmenopausal symptoms. The ability of isoflavones to prevent cancer and other chronic diseases largely depends on pharmacokinetic properties of these compounds, in particular absorption and distribution to the target tissue. The chemical form in which isoflavones occur is important because it influences their bioavailability and, therefore, their biological activity. Glucose-conjugated isoflavones are highly polar, water-soluble compounds. They are hardly absorbed by the intestinal epithelium and have weaker biological activities than the corresponding aglycone. Different microbial families of colon can transform glycosylated isoflavones into aglycones. Clinical studies show important differences between the aglycone and conjugated forms of genistein and daidzein. The evaluation of isoflavone metabolism and bioavailability is crucial to understanding their biological effects. Lipid-based formulations such as drug incorporation into oils, emulsions and self-microemulsifying formulations have been introduced to increase bioavailability. Complexation with cyclodextrin also represent a valid method to improve the physicochemical characteristics of these substances in order to be absorbed and distributed to target tissues. We review and discuss pharmacokinetic issues that critically influence the biological activity of isoflavones.
330 citations
TL;DR: Several possible molecular mechanisms, including the effects of GEN as an agonist of ERβ, epigenetic and genome-wide effects, activation of peroxisome proliferator-activated receptors, induction of apoptosis and stimulation of autophagy, involved in the chemo-preventive effects ofGEN on breast cancer are summarized.
198 citations
TL;DR: Results suggest that most of the phenolic compounds released following in vitro gastrointestinal digestion were sufficiently available to be absorbed and could contribute health benefits.
193 citations
TL;DR: There is lack of evidence showing harm from use of soy with respect to risk of breast cancer or recurrence, based on long term observational data, and better evidence confirming safety is required before use of high dose isoflavones can be recommended for breast cancer patients.
Abstract: Background
Soy and red clover isoflavones are controversial due to purported estrogenic activity and possible effects on breast cancer. We conducted a systematic review of soy and red clover for efficacy in improving menopausal symptoms in women with breast cancer, and for potential impact on risk of breast cancer incidence or recurrence.
142 citations
TL;DR: It is shown that isoflavones, especially genistein, could promote colon cancer cell growth inhibition and facilitate apoptosis and cell cycle arrest in the G2/M phase and the ATM/p53-p21 cross-regulatory network may play a crucial role in mediating the anticarcinogenic activities of genisteIn in colon cancer.
Abstract: Soybean isoflavones have been used as a potential preventive agent in anticancer research for many years. Genistein is one of the most active flavonoids in soybeans. Accumulating evidence suggests that genistein alters a variety of biological processes in estrogen-related malignancies, such as breast and prostate cancers. However, the molecular mechanism of genistein in the prevention of human colon cancer remains unclear. Here we attempted to elucidate the anticarcinogenic mechanism of genistein in human colon cancer cells. First we evaluated the growth inhibitory effect of genistein and two other isoflavones, daidzein and biochanin A, on HCT-116 and SW-480 human colon cancer cells. In addition, flow cytometry was performed to observe the morphological changes in HCT-116/SW-480 cells undergoing apoptosis or cell cycle arrest, which had been visualized using Annexin V-FITC and/or propidium iodide staining. Real-time PCR and western blot analyses were also employed to study the changes in expression of several important genes associated with cell cycle regulation. Our data showed that genistein, daidzein and biochanin A exhibited growth inhibitory effects on HCT-116/SW-480 colon cancer cells and promoted apoptosis. Genistein showed a significantly greater effect than the other two compounds, in a time- and dose-dependent manner. In addition, genistein caused cell cycle arrest in the G2/M phase, which was accompanied by activation of ATM/p53, p21waf1/cip1 and GADD45α as well as downregulation of cdc2 and cdc25A demonstrated by q-PCR and immunoblotting assay. Interestingly, genistein induced G2/M cell cycle arrest in a p53-dependent manner. These findings exemplify that isoflavones, especially genistein, could promote colon cancer cell growth inhibition and facilitate apoptosis and cell cycle arrest in the G2/M phase. The ATM/p53-p21 cross-regulatory network may play a crucial role in mediating the anticarcinogenic activities of genistein in colon cancer.
131 citations
TL;DR: It was hypothesized that the function of soybean isoflavones in the prevention and treatment of various diseases results from their phytoestrogen and antioxidant properties, and it is recommended that the risks of soy is oflavone intake as food and/or medical treatment be further evaluated.
Abstract: Soy isoflavones are compounds found in soybean and soybean products. They have been reported to possess numerous physiological properties, such as antitumor, anti-menopausal (female) osteoporosis and anti-aging. They have also been reported to improve learning and memory skills in menopausal women and aid in the prevention and treatment of heart disease, diabetes and Kawasaki disease (KD). In this review, the effects of soy isoflavones on various diseases were analyzed. Based on the analysis, it was hypothesized that the function of soybean isoflavones in the prevention and treatment of various diseases results from their phytoestrogen and antioxidant properties. However, due to their phytoestrogen properties, it is recommended that the risks of soy isoflavone intake as food and/or medical treatment be further evaluated.
130 citations
TL;DR: The overview presented reveals that the authors are only at the start of unraveling the complex underlying mode of action for effects of isoflavones, both beneficial or adverse, on cell proliferation and cancer risks, and that whatever model system will be applied, its relevance to human tissues with respect to ERα and ERβ levels, co-repressor and co-activator characteristics needs to be considered and defined.
Abstract: Isoflavones are phytoestrogens that have been linked to both beneficial as well as adverse effects in relation to cell proliferation and cancer risks. The present article presents an overview of these seemingly contradicting health effects and of mechanisms that could be involved in this dualistic mode of action. One mechanism relates to the different ultimate cellular effects of activation of estrogen receptor (ER) α, promoting cell proliferation, and of ERβ, promoting apoptosis, with the major soy isoflavones genistein and daidzein activating especially ERβ. A second mode of action includes the role of epigenetics, including effects of isoflavones on DNA methylation, histone modification and miRNA expression patterns. The overview presented reveals that we are only at the start of unraveling the complex underlying mode of action for effects of isoflavones, both beneficial or adverse, on cell proliferation and cancer risks. It is evident that whatever model system will be applied, its relevance to human tissues with respect to ERα and ERβ levels, co-repressor and co-activator characteristics as well as its relevance to human exposure regimens, needs to be considered and defined.
105 citations
TL;DR: The review describes how exposure of soybean-derived phytoestrogens can have adverse effects on reproductive performance in female adults.
Abstract: Phytoestrogens, polyphenolic compounds derived from plants, are more and more common constituents of human and animal diets. In most of the cases, these chemicals are much less potent than endogenous estrogens but exert their biological effects via similar mechanisms of action. The most common source of phytoestrogen exposure to humans as well as ruminants is soybean-derived foods that are rich in the isoflavones genistein and daidzein being metabolized in the digestive tract to even more potent metabolites—para-ethyl-phenol and equol. Phytoestrogens have recently come into considerable interest due to the increasing information on their adverse effects in human and animal reproduction, increasing the number of people substituting animal proteins with plant-derived proteins. Finally, the soybean becomes the main source of protein in animal fodder because of an absolute prohibition of bone meal use for animal feeding in 1995 in Europe. The review describes how exposure of soybean-derived phytoestrogens can have adverse effects on reproductive performance in female adults.
97 citations
TL;DR: Gut bacteria play a key role in the metabolism of dietary isoflavones, thereby influencing the availability and bioactivation of these polyphenols in the intestine and identifying a cluster of eight genes encoding the daidzein-induced proteins.
Abstract: Gut bacteria play a key role in the metabolism of dietary isoflavones, thereby influencing the availability and bioactivation of these polyphenols in the intestine. The human intestinal bacterium Slackia isoflavoniconvertens converts the main soybean isoflavones daidzein and genistein to equol and 5-hydroxy-equol, respectively. Cell extracts of S. isoflavoniconvertens catalyzed the conversion of daidzein via dihydrodaidzein to equol and that of genistein to dihydrogenistein. Growth of S. isoflavoniconvertens in the presence of daidzein led to the induction of several proteins as observed by two-dimensional difference gel electrophoresis. Based on determined peptide sequences, we identified a cluster of eight genes encoding the daidzein-induced proteins. Heterologous expression of three of these genes in Escherichia coli and enzyme activity tests with the resulting cell extracts identified the corresponding gene products as a daidzein reductase (DZNR), a dihydrodaidzein reductase (DHDR), and a tetrahydrodaidzein reductase (THDR). The recombinant DZNR also converted genistein to dihydrogenistein at higher rates than were observed for the conversion of daidzein to dihydrodaidzein. Higher rates were also observed with cell extracts of S. isoflavoniconvertens. The recombinant DHDR and THDR catalyzed the reduction of dihydrodaidzein to equol, while the corresponding conversion of dihydrogenistein to 5-hydroxy-equol was not observed. The DZNR, DHDR, and THDR were expressed as Strep-tag fusion proteins and subsequently purified by affinity chromatography. The purified enzymes were further characterized with regard to their activity, stereochemistry, quaternary structure, and content of flavin cofactors.
86 citations
TL;DR: The main objective of this study is to identify a soy isoflavone combination with lower levels of daidzein and genistein to be a more efficacious and safer chemo-preventive agent for PCa.
80 citations
TL;DR: Results suggest that decreases in cell proliferation due togenistein may result from the inhibition of cellular topo II and that genistein, a major soy isoflavone, may be an anticancer food component.
Abstract: The inhibitory activity of 3 soy isoflavones (daidzein, genistein and glycitein) and their glycosides (daidzin, genistin and glycitin) on mammalian DNA polymerases (pols) and topoisomerases (topos) was investigated. Of the compounds tested, only genistein selectively inhibited human topo II activity and had an IC50 value of 37.5 µM. These isoflavones had no effect on the activity of human topo I; mammalian pols α, β, γ and κ; or on any other DNA metabolic enzyme tested. Thermal transition analysis indicated that genistein did not influence the direct binding to double-stranded DNA. Genistein prevented the proliferation of HCT116 human colon carcinoma cells with an LD50 of 94.0 µM and it halted the cell cycle in G2/M phase. These results suggest that decreases in cell proliferation due to genistein may result from the inhibition of cellular topo II and that genistein, a major soy isoflavone, may be an anticancer food component. The relationship between the structures and these bioactivities of soy isoflavones is discussed.
TL;DR: It is demonstrated that soy phytoestrogens tend to modify transcription through the demethylation and acetylation of histones in breast cancer cell lines.
Abstract: Aim: The isoflavones genistein, daidzein and equol (daidzein metabolite) have been reported to interact with epigenetic modifications, specifically hypermethylation of tumor suppressor genes. The objective of this study was to analyze and understand the mechanisms by which phytoestrogens act on chromatin in breast cancer cell lines. Materials & methods: Two breast cancer cell lines, MCF-7 and MDA-MB 231, were treated with genistein (18.5 µM), daidzein (78.5 µM), equol (12.8 µM), 17β-estradiol (10 nM) and suberoylanilide hydroxamic acid (1 µM) for 48 h. A control with untreated cells was performed. 17β-estradiol and an anti-HDAC were used to compare their actions with phytoestrogens. The chromatin immunoprecipitation coupled with quantitative PCR was used to follow soy phytoestrogen effects on H3 and H4 histones on H3K27me3, H3K9me3, H3K4me3, H4K8ac and H3K4ac marks, and we selected six genes (EZH2, BRCA1, ERα, ERβ, SRC3 and P300) for analysis. Results: Soy phytoestrogens induced a decrease in trimethylate...
TL;DR: The isoflavones daidzein and genistein showed anti-breast cancer activity, which was associated with expression of the ERα and c‑erbB‑2 receptors.
Abstract: In this study, we investigated the antiproliferative activity of the isoflavones daidzein and genistein in three breast cancer cell lines with different patterns of estrogen receptor (ER) and c‑erbB‑2 protein expression (ERα‑positive MCF‑7 cells, c‑erbB‑2‑positive SK‑BR‑3 cells and ERα/c‑erbB‑2‑positive ZR‑75‑1). After treatment at various concentrations (1‑200 µM for 72 h), the effect of daidzein and genistein on the proliferation of different cell types varied; these effects were found to be associated with ERα and c‑erbB‑2 expression. Daidzein and genistein exhibited biphasic effects (stimulatory or inhibitory) on proliferation and ERα expression in MCF‑7 cells. Although 1 µM daidzein significantly stimulated cell growth, ERα expression was unaffected. However, genistein showed marked increases in proliferation and ERα expression after exposure to <10 µM genistein. Notably, the inhibition of cell proliferation by 200 µM genistein was greater compared to that by daidzein at the same concentration. Daidzein and genistein significantly inhibited proliferation of SK‑BR‑3 and ZR‑75‑1 cells in a dose‑dependent manner. In addition, ERα and c‑erbB‑2 expression was reduced by daidzein and genistein in both SK‑BR‑3 and ZR‑75‑1 cells in a dose‑dependent manner. However, the effect of genistein was greater compared to that of daidzein. In conclusion, the isoflavones daidzein and genistein showed anti‑breast cancer activity, which was associated with expression of the ERα and c‑erbB‑2 receptors.
TL;DR: Soy protein supplementation may reduce levels of E-selectin and leptin, and further research is warranted to investigate the mechanisms through which protein may confer protective effects on novel CVD risk factors.
Abstract: Cardiovascular disease (CVD) is the leading cause of death in the United States and the world. Clinical trials have suggested that soybean protein lowers lipids and blood pressure. The effect of soybean protein on novel CVD risk factors has not been well studied. The objective of this study was to examine the effect of soybean protein on biomarkers of inflammation, endothelial dysfunction and adipocytokines. The effect of 8 weeks of 40 g of soybean protein supplement (89.3 mg isoflavones), 40 g of milk protein supplement and 40 g of complex carbohydrate placebo was examined in a randomized, placebo-controlled, double-blind, three-phase crossover trial among adults in New Orleans, Louisiana and Jackson, Mississippi. Plasma levels of inflammation biomarkers (C-reactive protein, interleukin-6, tumor necrosis factor-α), endothelial dysfunction biomarkers (E-selectin, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, thrombomodulin) and adipocytokines (high-molecular weight adiponectin, leptin, resistin) were measured at baseline and at the end of each intervention using immunoturbidimetric and enzyme-linked immunosorbent assay techniques. Soy protein supplementation resulted in a significant mean net change (95% confidence interval) in plasma E-selectin of −3.93 ng/ml (−7.05 to −0.81 ng/ml; P=0.014) compared with milk protein, and in plasma leptin of −2089.8 pg/ml (−3689.3 to −490.3 pg/ml; P=0.011) compared with carbohydrate. There were no significant changes in any other risk factors. Soy protein supplementation may reduce levels of E-selectin and leptin. Further research is warranted to investigate the mechanisms through which protein may confer protective effects on novel CVD risk factors.
TL;DR: It is suggested that pharmacological treatment with isoflavones regulates metabolic alterations associated with enhancement of cell proliferation and reduction of apoptosis and gliosis in response to high-fat diet.
Abstract: Soy extracts have been claimed to be neuroprotective against brain insults, an effect related to the estrogenic properties of isoflavones. However, the effects of individual isoflavones on obesity-induced disruption of adult neurogenesis have not yet been analyzed. In the present study we explore the effects of pharmacological administration of daidzein, a main soy isoflavone, in cell proliferation, cell apoptosis and gliosis in the adult hippocampus of animals exposed to a very high-fat diet. Rats made obese after 12-week exposure to a standard or high-fat (HFD, 60%) diets were treated with daidzein (50 mg kg−1) for 13 days. Then, plasma levels of metabolites and metabolic hormones, cell proliferation in the subgranular zone of the dentate gyrus (SGZ), and immunohistochemical markers of hippocampal cell apoptosis (caspase-3), gliosis (GFAP and Iba-1), food reward factor FosB and estrogen receptor alpha (ERα) were analyzed. Treatment with daidzein reduced food/caloric intake and body weight gain in obese rats. This was associated with glucose tolerance, low levels of HDL-cholesterol, insulin, adiponectin and testosterone, and high levels of leptin and 17β-estradiol. Daidzein increased the number of phospho-histone H3 and 5-bromo-2-deoxyuridine (BrdU)-ir cells detected in the SGZ of standard diet and HFD-fed rats. Daidzein reversed the HFD-associated enhanced immunohistochemical expression of caspase-3, FosB, GFAP, Iba-1 and ERα in the hippocampus, being more prominent in the dentate gyrus. These results suggest that pharmacological treatment with isoflavones regulates metabolic alterations associated with enhancement of cell proliferation and reduction of apoptosis and gliosis in response to high-fat diet.
TL;DR: Anti-inflammatory effect of genistein on endothelial cells may be associated with the activation of Nrf2/HO-1 pathway.
TL;DR: It appears that soy isoflavones do not function as an estrogen, but rather exhibit anti-estrogenic properties, however, their metabolism differs between humans and animals and therefore the outcomes of animal studies may not be applicable to humans.
Abstract: Epidemiological and migratory evidence suggests that dietary soy consumption can lower the risk for breast cancer The role of soy isoflavones in cancer prevention and promotion is somewhat unclear There are two views in terms of soy isoflavones and breast cancer One line of evidence suggests that soy and its isoflavones have exhibited cancer-preventive properties including lengthening the menstrual cycle, altering estrogen metabolism away from cancerous compounds, and demonstrating anti-proliferative properties in vivo On the contrary, isoflavones found in soy products are suggested to behave as weak estrogens and as such, much speculation surrounds the influence of soy and/or its isoflavones on hormone-receptor-positive cancers The objective of this review is to present the latest knowledge regarding the role of soy and its isoflavones with the development and advancement of breast cancer, the safety of soy isoflavones for breast cancer survivors, and a comparison of the carcinogenic effects in animal models following soy isoflavone and estrogen administration This review compares and contrasts literature in terms of the anti-cancer and cancer-promoting effects of soy isoflavones and estrogen in humans and animal models In conclusion, current human and animal data provide evidence for several anticancer properties of soy and/or its isoflavones Although the specific quantities and constituents responsible for the observed anti-cancer effects have not been elucidated, it appears that soy isoflavones do not function as an estrogen, but rather exhibit anti-estrogenic properties However, their metabolism differs between humans and animals and therefore the outcomes of animal studies may not be applicable to humans The majority of breast cancer cases are hormone-receptor-positive; therefore, soy isoflavones should be considered a potential anti-cancer therapeutic agent and warrant further investigation
TL;DR: Soy protein, in combination with isoflavones, would have the largest positive effect on coronary heart disease risk factors (serum lipids and inflammatory markers) compared with either intervention alone orEither alone or together, soy protein and is oflavones should not be considered an effective intervention to prevent cardiovascular disease because of lipid modification in healthy late postmenopausal women lacking the ability to produce equol.
TL;DR: If equol can reduce risk ofPCa, a possible strategy for reducing the risk of PCa may be to increase the proportion of equol-producers by changing the intestinal flora to carrying an equo-producing bacterium with dietary alteration or probiotic technology.
Abstract: Background: The age-adjusted incidence rate of prostate cancer (PCa) has been reported to be lower among Asians than Western populations. A traditional Japanese meal, high in soybean products or isoflavones, may be associated with a decreased risk of PCa. Equol, which is converted from daidzein by human intestinal flora, is biologically more active than any other isoflavone aglycone. Materials and Methods: We reviewed not only recent epidemiological studies on association of isoflavones with PCa risk, but also recent research on human intestinal bacteria responsible for converting daidzein into equol. Studies were systematically searched from the database published within the last 5 years of from 2008-2012. Results: Five out of 6 articles showed significant association of isoflavones with a decreased risk of PCa, and two of them consistently showed that equol-producers carry a significantly reduced risk of PCa. Furthermore, 5 human intestinal bacteria that can convert daidzein into equol were identified in the last 5 years. Conclusions: If equol can reduce risk of PCa, a possible strategy for reducing the risk of PCa may be to increase the proportion of equol-producers by changing the intestinal flora to carrying an equol-producing bacterium with dietary alteration or probiotic technology.
TL;DR: The results suggest that isoflavones suppress myotube atrophy in skeletal muscle cells through activation of SIRT1 signaling, which could provide a novel therapeutic approach against inflammation-related muscle atrophy.
Abstract: Proinflammatory cytokines are factors that induce ubiquitin-proteasome-dependent proteolysis in skeletal muscle, causing muscle atrophy. Although isoflavones, as potent antioxidative nutrients, have been known to reduce muscle damage during the catabolic state, the non-antioxidant effects of isoflavones against muscle atrophy are not well known. Here we report on the inhibitory effects of isoflavones such as genistein and daidzein on muscle atrophy caused by tumor necrosis factor (TNF)-α treatment. In C2C12 myotubes, TNF-α treatment markedly elevated the expression of the muscle-specific ubiquitin ligase MuRF1, but not of atrogin-1, leading to myotube atrophy. We found that MuRF1 promoter activity was mediated by acetylation of p65, a subunit of NFκB, a downstream target of the TNF-α signaling pathway; increased MuRF1 promoter activity was abolished by SIRT1, which is associated with deacetylation of p65. Of interest, isoflavones induced expression of SIRT1 mRNA and phosphorylation of AMP kinase, which is well known to stimulate SIRT1 expression, although there was no direct effect on SIRT1 activation. Moreover, isoflavones significantly suppressed MuRF1 promoter activity and myotube atrophy induced by TNF-α in C2C12 myotubes. These results suggest that isoflavones suppress myotube atrophy in skeletal muscle cells through activation of SIRT1 signaling. Thus, the efficacy of isoflavones could provide a novel therapeutic approach against inflammation-related muscle atrophy.
TL;DR: It is suggested that xylitol has the potential to affect the metabolism of daidzein by altering the metabolic activity of the intestinal microbiota and/or gut environment and, given that equol affects bone health, dietaryxylitol plus isoflavonoids may exert a favorable effect on bone health.
Abstract: This study examined the effects of xylitol on mouse intestinal microbiota and urinary isoflavonoids. Xylitol is classified as a sugar alcohol and used as a food additive. The intestinal microbiota seems to play an important role in isoflavone metabolism. Xylitol feeding appears to affect the gut microbiota. We hypothesized that dietary xylitol changes intestinal microbiota and, therefore, the metabolism of isoflavonoids in mice. Male mice were randomly divided into two groups: those fed a 0.05% daidzein with 5% xylitol diet (XD group) and those fed a 0.05% daidzein-containing control diet (CD group) for 28 days. Plasma total cholesterol concentrations were significantly lower in the XD group than in the CD group (p < 0.05). Urinary amounts of equol were significantly higher in the XD group than in the CD group (p < 0.05). The fecal lipid contents (% dry weight) were significantly greater in the XD group than in the CD group (p < 0.01). The cecal microbiota differed between the two dietary groups. The occupation ratios of Bacteroides were significantly greater in the CD than in the XD group (p < 0.05). This study suggests that xylitol has the potential to affect the metabolism of daidzein by altering the metabolic activity of the intestinal microbiota and/or gut environment. Given that equol affects bone health, dietary xylitol plus isoflavonoids may exert a favorable effect on bone health.
TL;DR: In this paper, the authors compared the conventional and organic crops of BRS258 soybeans obtained concurrently by the Agricultural Center of Palma (RS, Brazil) in relation to protein, total phenolics, isoflavone contents, in vitro antioxidant capacity, and trypsin inhibitory activity.
TL;DR: The geniVida™ bone blend (GBB) may help to prevent osteoporosis and reduce fracture risk, at least at the hip, in postmenopausal women.
Abstract: Purpose
Many postmenopausal women desire non-pharmaceutical alternatives to hormone therapy for protection against osteoporosis. Soybean isoflavones, especially genistein, are being studied for this purpose. This study examined the effects of synthetic genistein in combination with other potential bone-protective dietary molecules on bone mineral density (BMD) in early postmenopausal women.
TL;DR: All neuraminidase compounds screened were found to be reversible noncompetitive inhibitors and the most active NA inhibitors were proven to be present in the native roots in high quantities by HPLC and LC-DAD-ESI/MS.
TL;DR: The presence of equol-producing bacteria in soy product consumers means that the consumption of such products for prolonged periods leads to lower cardiovascular risk, reduced incidence of prostate and breast cancer, and greater relief from symptoms related to the menopause such as hot flushes and osteoporosis.
Abstract: The bioavailability of soy isoflavones depends on the composition of the microflora for each subject. Bacteria act on different isoflavones with increased or reduced absorption and cause biotransformation of these compounds into metabolites with higher biological activity. S-equol is the most important metabolite and only 25–65 % of the population have the microflora that produces this compound. The presence of equol-producing bacteria in soy product consumers means that the consumption of such products for prolonged periods leads to lower cardiovascular risk, reduced incidence of prostate and breast cancer, and greater relief from symptoms related to the menopause such as hot flushes and osteoporosis.
TL;DR: β-Glucosidase-positive probiotic bacteria were proved to release the aglycones of isoflavones and lignans in vitro, but studies in vivo are scarce, and activation of specific phytochemicals by probiotics still needs substantial efforts to be proved.
Abstract: Many healthy phytochemicals occur in food in the form of esters, glycoconjugates, or polymers, which are not directly bioavailable. Probiotic lactobacilli and bifidobacteria, which have evolved within the colonic ecosystem where indigestible oligo- and polysaccharides are their sole carbon sources, bear several glycosyl-hydrolases and can contribute to release the aglycones from glycoconjugated phytochemicals. Among the glycosyl-hydrolases, β-glucosidases are the most pertinent, because many phytochemicals are glucoconjugates. β-Glucosidase-positive probiotic bacteria were proved to release the aglycones of isoflavones and lignans in vitro, but studies in vivo are scarce. A positive correlation between probiotic consumption and urinary and/or plasma levels of isoflavone or lignan metabolites was not established. However, the strains used in the trials were not validated for the enzymatic properties or for the ability to hydrolyze lignans or isoflavones. Thus, activation of specific phytochemicals by probiotic bacteria still needs substantial efforts to be proved.
TL;DR: The results indicated that the MSPE-HPLC-MS/MS analytical method was useful for fast determination of isoflavones in soymilk and other liquid soybean products.
Abstract: Most protocols of sample preparation for isoflavone determination in soymilk and other liquid soybean products involves tedious freeze-drying and time-consuming extraction procedures. We report a facile and rapid magnetic solid-phase extraction (MSPE) of isoflavones from soymilk for subsequent high-performance liquid chromatography electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) analysis. The extraction was based on the selective binding of isoflavones to baicalin-functionalized core-shell magnetic nanoparticles (BMNPs). The proposed MSPE-HPLC-MS/MS analytical method had a linear calibration curve in the concentration range from 0.3 to 80 mg/L isoflavones. With the use of calycosin, an isomer of one of the isoflavones targeted as an internal standard, interday (5 days) precisions of the slope and intercept of the calibration curves were found to be in the range between 2.5% and 3.6% (RSD, n = 5). Six isoflavones, that is, daidzein, glycitein, genistein, daidzin, glycitin, and genistin were detected in commercial soymilk samples and quantified by the proposed analytical method. The results indicated that the method was useful for fast determination of isoflavones in soymilk and other liquid soybean products.
TL;DR: A 6-month randomized controlled trial in prediabetic postmenopausal women indicated that soy protein and isoflavones had no significant effect on BP and endothelial molecules; however, a favorable reduction on SBP, sICAM-1 and E-selectin was observed among women with initial elevated BP.
Abstract: Background:Despite data from animal models and observational studies that are generally supportive for the soy/isoflavones lowering blood pressure (BP) and improving vascular function, the current findings from clinical trials are still inconclusive.Objectives:To examine whether soy protein with iso
TL;DR: The data suggest that genistein, DHG and DHD were efficiently transported by passive diffusion according to the pH-partition hypothesis and were markedly more permeable than their parent isoflavones; they were therefore difficult to transport by the efflux effect, and glucuronidation/sulfation was limited by the flux time.
Abstract: Isoflavone data concerning the metabolism and permeability on intestinal epithelial cells are scarce, particularly for microbial isoflavone metabolites. This study evaluates the absorption mechanisms for the isoflavones, genistein and daidzein, and their microbial metabolites, dihydrogenistein (DHG) and dihydrodaidzein (DHD). The permeability characteristics of isoflavones were compared by using the Caco-2 human colon adenocarcinoma cell line for a parallel artificial membrane permeability assay, and comparing their physicochemical properties. The data suggest that genistein, DHG and DHD were efficiently transported by passive diffusion according to the pH-partition hypothesis. Genistein was conjugated by phase II metabolizing enzymes and acted as a substrate of the breast cancer resistance protein (BCRP). Daidzein was not conjugated but did act as a substrate for BCRP, multidrug resistance-associated proteins, and P-glycoprotein. In contrast, DHG and DHD were markedly more permeable than their parent isoflavones; they were therefore difficult to transport by the efflux effect, and glucuronidation/sulfation was limited by the flux time.