Dietary Phytoestrogens to Prevent Cardiovascular Disease

Phytoestrogenic Activity of Blackcurrant Anthocyanins Is Partially Mediated through Estrogen Receptor Beta

Phytoestrogens are plant compounds with estrogenic effects found in many foods. We have previously reported phytoestrogen activity of blackcurrant anthocyanins (cyanidin-3-glucoside, cyanidin-3-rutinoside, delphinidin-3-glucoside, and delphinidin-3-rutinoside) via the estrogen receptor (ER)α. In this study, we investigated the participation of ERβ in the phytoestrogen activity of these anthocyanins. Blackcurrant anthocyanin induced ERβ-mediated transcriptional activity, and the IC₅₀ of ERβ was lower than that of ERα, indicating that blackcurrant anthocyanins have a higher binding affinity to ERβ. In silico docking analysis of cyanidin and delphinidin, the core portions of the compound that fits within the ligand-binding pocket of ERβ, showed that similarly to 17β-estradiol, hydrogen bonds formed with the ERβ residues Glu305, Arg346, and His475. No fitting placement of glucoside or rutinoside sugar chains within the ligand-binding pocket of ERβ-estradiol complex was detected. However, as the conformation of helices 3 and 12 in ERβ varies depending on the ligand, we suggest that the surrounding structure, including these helices, adopts a conformation capable of accommodating glucoside or rutinoside. Comparison of ERα and ERβ docking structures revealed that the selectivity for ERβ is higher than that for ERα, similar to genistein. These results show that blackcurrant anthocyanins exert phytoestrogen activity via ERβ.

Greater flavonoid intake is associated with improved CVD risk factors in US adults

Epidemiological studies have reported that diets high in flavonoids are associated with a reduced risk of CVD. However, evidence on the association of dietary flavonoid intake with CVD risk factors is still scarce. The present study aimed to investigate the association of dietary flavonoid intake with CVD risk factors among US adults in the National Health and Nutrition Examination Survey (NHANES) 2007-2012. A total of 4042 US adults aged 19 years and older from the NHANES 2007-2012 participated in this cross-sectional, population-based study. Intakes of total and individual flavonoids were estimated from 2-d 24-h diet recall data by matching with the expanded US Department of Agriculture flavonoid, isoflavone and proanthocyanidin databases. After adjusting for covariates, increased HDL-cholesterol was associated with higher total flavonoid intake (0·54 % change). TAG and TAG:HDL-cholesterol ratio were inversely associated with anthocyanidin (-1·25 % change for TAG; -1·60 % change for TAG:HDL-cholesterol ratio) and total flavonoid intakes (-1·31 % change for TAG; -1·83 % change for TAG:HDL-cholesterol ratio), respectively. Insulin and homoeostasis model assessment for insulin resistance (HOMA-IR) were inversely associated with flavone (for insulin, -3·18 % change; 95 % CI -5·85, -0·44; for HOMA-IR, -3·10 % change; 95 % CI -5·93, -0·19) and isoflavone intakes (for insulin, -3·11 % change; 95 % CI -5·46, -0·70; for HOMA-IR, -4·01 % change; 95 % CI -6·67, -1·27). BMI was negatively associated with anthocyanidin intake (-0·60 % change). This study showed that higher flavonoid intake was associated with improved CVD risk factors. Further research is warranted to confirm the findings from this study as these associations were moderate in strength.

Icariin exerts estrogen-like activity in ameliorating EAE via mediating estrogen receptor β, modulating HPA function and glucocorticoid receptor expression

BACKGROUND

Estrogen exerts neuroprotective and anti-inflammatory effects in EAE and multiple sclerosis (MS), but its clinical application is hindered due to side effects and risk of tumor. Phytoestrogen structurally or functionally mimics estrogen with fewer side effects than endogenous estrogen. Icariin (ICA), an active component of Epimedium extracts, demonstrates estrogen-like neuroprotective effects. However, it is unclear whether ICA is effective in EAE and what are the underlying mechanisms.

OBJECTIVE

To determine the therapeutic effects of ICA in EAE and explore the possible mechanisms.

METHODS

C57BL/6 EAE mice were treated with Diethylstilbestrol, different dose of ICA and mid-dose ICA combined with ICI 182780. The clinical scores and serum Interleukin-17 (IL-17), Corticosterone (CORT) concentrations were then analyzed. Western blot were performed to investigate the expressions of glucocorticoid receptor (GR), estrogen receptor alpha (ERα) and ERβ in the cerebral white matter of EAE mice.

RESULTS

High dose ICA is equally effective in ameliorating neurological signs of EAE as estrogen. Estrogen and ICA has no effects on serum concentrations of IL-17 in EAE. While the CORT levels were decreased by ICA at mid or high doses, the expressions of GR, ERα and ERβ were up-regulated by estrogen or different doses of ICA in a dosedependent manner. Estrogen induced the elevation of ERα more markedly than ICA. In contrast, ICA at mid and high doses promoted ERβ more significantly than estrogen.

CONCLUSION

ICA exerts estrogen-like activity in ameliorating EAE via mediating ERβ, modulating HPA function and up-regulating the expression of GR in cerebral white matter. ICA may be a promising therapeutic option for MS.

Phytoestrogenic activity of blackcurrant (Ribes nigrum) anthocyanins is mediated through estrogen receptor alpha

SCOPE

Blackcurrants (Ribes nigrum L., Grossulariaceae) contain high amounts of anthocyanin polyphenols, which have antioxidant and anti-carcinogenic health benefits. This study analyzed the potential phytoestrogenic effects of blackcurrant extract (BCE) in breast cancer (MCF-7) and human endometrial cancer (Ishikawa) cell lines that over-express estrogen receptor alpha (ERα), as well as in immature female rats.

METHODS AND RESULTS

Microarray analysis and Ingenuity® Pathway Analysis showed that BCE activated the ERα pathway, whereas quantitative-PCR confirmed that BCE and four types of anthocyanins up-regulated genes downstream of ERα. BCE (0.1-1.0 μg/mL) and anthocyanins (0.1-10 μM) induced MCF-7 cell proliferation; however, this effect was blocked by ER antagonist fulvestrant. Flow cytometry showed that anthocyanins reduced and increased the number of MCF-7 cells in the G0/G1 and G2/M phases, respectively. Anthocyanins stimulated ERα transcriptional activity in human ERα reporter assays and induced alkaline phosphatase activity in Ishikawa cells. Competition assays and in silico analysis indicated that anthocyanins bind to ERα. Finally, BCE focally induced stratification of columnar epithelial cells in the rat uterus and increased cytoplasmic mucin levels in these cells.

CONCLUSION

These results suggest that blackcurrant anthocyanins act as phytoestrogens in vitro and in vivo.

Icariin has synergistic effects with methylprednisolone to ameliorate EAE via modulating HPA function, promoting anti-inflammatory and anti-apoptotic effects

BACKGROUND

High-dose methylprednisolone (MP) is a clinically recommended therapeutic regimen for Multiple Sclerosis (MS), whereas some dreadful complications induced by it remain inevitable. Studies implied that estrogens might play neuroprotective and anti-inflammatory roles in EAE and MS and promote glucocorticoid efficacy. Icariin (ICA), a primary active component of Epimedium extracts, also possesses neuroprotective and estrogen-like effects with less adverse complication than estrogen. However, rare study focuses ICA's effects on MS or EAE.

OBJECTIVE

Our purpose is to determine whether ICA has synergistic effects with MP in treating EAE and explore the possible mechanisms.

METHODS

C57BL/6 EAE mice were received different dose of ICA combined with MP and single MP treatment. Then, the clinical scores and serum Interleukin-17 (IL-17), Corticosterone (CORT), Adrenocorticotropic Hormone (ACTH) concentrations were analyzed. Western blot and Flow Cytometry were used to investigate the expression of glucocorticoid receptor (GR) and cell apoptosis.

RESULTS

ICA has cooperative effects with MP in decreasing serum IL-17 and CORT concentrations, up-regulating the expression of GR in cerebral white matter and attenuating the cell apoptosis in spinal cord, especially high-dose ICA combined with MP.

CONCLUSION

ICA has synergistic effects with MP to ameliorate EAE via modulating hypothalamic-pituitary-adrenal (HPA) function, promoting anti-inflammatory and anti-apoptotic effects. ICA could be considered as a promising therapeutic option for MS.

Prenatal exposure to the phytoestrogen daidzein resulted in persistent changes in ovarian surface epithelial cell height, folliculogenesis, and estrus phase length in adult Sprague-Dawley rat offspring

Daidzein (DZ), an isoflavone with the potential to interfere with estrogen signaling, is found in soy products, which have gained popularity due to purported beneficial effects on the cardiovascular and skeletal systems and potential antineoplastic properties. However, the ingestion of phytoestrogens has been associated with impaired reproductive function in many species. The aim of this study was to determine the long-term effects on the ovaries of rat offspring exposed to DZ or ethinyl estradiol (EE) during prenatal development. Gravid rats were administered either vehicle or 5 or 60 mg DZ/kg body weight/d or 0.002 mg 17-α EE /kg body weight/d on gestational days 6-21. Ovarian-related endpoints were investigated during adulthood in female offspring. The mean cell height of the ovarian surface epithelium was significantly reduced in all treated groups. Alterations in folliculogenesis included increased follicular atresia, a reduction in secondary and tertiary follicle numbers, and cyst formation. An elevated prevalence of a slightly prolonged estrus phase was also observed. The morphological changes to the ovarian surface epithelium are consistent with an antiproliferative effect, while ovarian folliculogenesis was adversely affected. The effects of the high dose DZ were similar to those observed with 17-α EE.

Simultaneous determination of 11 phytoestrogens in human serum using a 2 min liquid chromatography/tandem mass spectrometry method

A rapid 2 min liquid chromatography-tandem mass spectrometry (LC-MS/MS) method operating in multiple reaction ion monitoring mode was developed and validated that allows for the characterization and simultaneous quantification of 11 phytoestrogen metabolites with mass transitions m/z 241/119 (equol), 253/132 (daidzein), 255/149 (dihydrodaidzein), 257/108 (O-desmethylangolesin), 269/133 (genistein), 283/184 (glycitein), 267/191 (formononetin), 289/109 (biochanin A), 267/91 (coumestrol), enterodiol (301/253), and enterolactone (297/253). The method was demonstrated to be specific and sensitive, and a linear response for each phytoestrogen was observed over a range of 1-5000 ng/mL in human serum with the exception of dihydrodaidzein, whose lower limit of quantification was 2 ng/mL. The separation was carried out on a Synergi Polar-RP 2.5 micron (50 mm x 2.0 mm i.d.) column at 50 degrees C with water and acetonitrile (both containing 10 mM ammonium acetate) as the mobile phase under gradient conditions at a flow rate of 0.75 mL/min. This LC-MS/MS method is very useful for high-throughput analysis of phytoestrogens and proved to be simple, sensitive, reproducible, and reliable.

Fruit, vegetable and bean intake and mortality from cardiovascular disease among Japanese men and women: the JACC Study

To examine the association of plant-based food intakes with CVD and total mortality among Japanese. In the Japan Collaborative Cohort Study for Evaluation of Cancer Risk, 25 206 men and 34 279 women aged 40–79 years, whose fruit, vegetable and bean intakes were assessed by questionnaire at baseline in 1988–90, were followed for 13 years. Deaths from total stroke, stroke subtypes, CHD and total CVD, according to the International Classification for Diseases 10th Revision, were registered. During 756 054 person-years of follow-up, there were 559 deaths from total stroke, 258 from CHD, 1207 from total CVD and 4514 from total mortality for men, and for women, 494, 194, 1036 and 3092, respectively. Fruit intake was inversely associated with mortality from total stroke (the multivariable hazard ratio (HR (95 % CI)) in the highest v. lowest quartiles = 0·67 (0·55, 0·81)), total CVD (HR = 0·75 (0·66, 0·85)) and total mortality (HR = 0·86 (0·80, 0·92)). Vegetable intake was inversely associated with total CVD (HR = 0·88 (0·78, 0·99)). Bean intake was inversely associated with other CVD (HR = 0·79 (0·64, 0·98)), total CVD (HR = 0·84 (0·74, 0·95)) and total mortality (HR = 0·90 (0·84, 0·96)). Further adjustment for other plant-based foods did not alter the association of fruit intake with mortality from total stroke, total CVD and total mortality, but attenuated the associations of vegetables and beans with mortality risk. In conclusion, intakes of plant-based foods, particularly fruit intake, were associated with reduced mortality from CVD and all causes among Japanese men and women.

Short term effects on bone quality associated with consumption of soy protein isolate and other dietary protein sources in rapidly growing female rats

Beneficial effects of soy protein consumption on bone quality have been reported. The effects of other dietary protein sources such as whey protein hydrolysate (WPH) and rice protein isolate (RPI) on bone growth have been less well examined. The current study compared effects of feeding soy protein isolate (SPI), WPH and RPI for 14 d on tibial bone mineral density (BMD) and bone mineral content (BMC) in intact and ovariectomized (OVX) rapidly growing female rats relative to animals fed casein (CAS). The effects of estrogenic status on responses to SPI were also explored. Tibial peripheral quantitative computerized tomography (pQCT) showed all three protein sources had positive effects on either BMD or BMC relative to CAS (P < 0.05), but SPI had greater effects in both intact and OVX female rats. SPI and E2 had positive effects on BMD and BMC in OVX rats (P < 0.05). However, trabecular BMD was lower in a SPI + E2 group compared to a CAS + E2 group. In OVX rats, SPI increased serum bone formation markers, and serum from SPI-fed rats stimulated osteoblastogenesis in ex vivo. SPI also suppressed the bone resorption marker RatLaps (P < 0.05). Both SPI and E2 increased alkaline phosphatase gene expression in bone, but only SPI decreased receptor activator of nuclear factor-kappaB ligand (RANKL) and estrogen receptor gene expression (P < 0.05). These data suggest beneficial bone effects of a soy diet in rapidly growing animals and the potential for early soy consumption to increase peak bone mass.

Dietary soya intake alters plasma antioxidant status and lipid peroxidation in postmenopausal women with the metabolic syndrome

Postmenopausal women with the metabolic syndrome are at high risk of oxidative stress. Several studies have suggested possible antioxidant properties of soya, but little evidence is available regarding the effect of soya on oxidative stress in postmenopausal women with the metabolic syndrome. The objective of the present study was to determine the effects of soya consumption on plasma total antioxidant capacity (TAC) and malondialdehyde (MDA) level in postmenopausal women with the metabolic syndrome. A randomised cross-over trial was undertaken on forty-two postmenopausal women with the metabolic syndrome. Participants were randomly assigned to consume a control (Dietary Approaches to Stop Hypertension; DASH) diet, a soya protein diet, or a soya nut diet, each for 8 weeks. Red meat in the DASH diet (one serving per d) was replaced by soya protein in the soya protein period and by soya nuts in the soya nut period. Significant differences between the end values of the control diet, soya protein diet and soya nut diet were seen for MDA (0.70, 0.64 and 0.63 mumol/l; global P < 0.01). The results also showed a significant difference between the end values for TAC (1950, 2030 and 2110 mumol/l, respectively; P < 0.01). The difference from control for TAC was +4.5 % (P < 0.01) in the soya nut period and +5.8 % (P < 0.01) in the soya protein regimen. Both soya nuts and soya protein decreased MDA significantly compared with the control diet (difference from control was - 7.9 % (P < 0.01) in the soya nut period and - 9.4 % (P < 0.01) in the soya protein diet). We conclude that soya consumption reduces plasma MDA and increases plasma TAC levels in postmenopausal women with the metabolic syndrome.

High throughput quantification of phytoestrogens in human urine and serum using liquid chromatography/tandem mass spectrometry (LC-MS/MS)

Phytoestrogens are currently the subject of intense study owing to their potential protective effects against a number of complex diseases. However, in order to investigate the interactions between phytoestrogens and disease state effectively, it is necessary to have analytical methods which are sensitive, reproducible, and require low sample volumes. We report an assay for three isoflavones (daidzein, genistein, and glycitein), two metabolites of daidzein (equol and O-desmethylangolensin), three lignans (secoisolariciresinol, enterodiol, and enterolactone), and one flavanone (naringenin) in human urine and serum. A high throughput of samples has been achieved via the use of 96-well plate sample extraction and liquid chromatography/tandem mass spectrometry (LC-MS/MS) analysis incorporating column switching, thus making the assay suitable for use on large sample numbers, such as those found in epidemiological studies. The robustness of the assay was proven via the comparison of data generated on two different LC-MS/MS systems, with and without column switching.

Effect of isolated isoflavone supplementation on ABCA1-dependent cholesterol efflux potential in postmenopausal women

OBJECTIVE

Isoflavones may display beneficial health effects in postmenopausal women. We studied in a clinical trial whether isolated isoflavone treatment in postmenopausal women could affect reverse cholesterol transport as evaluated by adenosine triphosphate-binding cassette A1- (ABCA1), dependent cholesterol efflux from macrophages. In addition, various serum lipid and lipoprotein parameters were investigated. Furthermore, we separately assessed equol-producing and non-equol-producing women.

DESIGN

Postmenopausal women (n=56) were treated with either isoflavone or placebo tablets for 3 months in a crossover design, separated by a 2-month washout period. Fifteen women were classified as equol producers, and 15 women were classified as non-equol producers. Serum samples were collected before and after each treatment period. [H]-Cholesterol-labeled J774 macrophage cells, with and without ABCA1 up-regulation, were incubated with the samples, and ABCA1-dependent cholesterol efflux and serum lipid and lipoprotein levels were assessed.

RESULTS

Serum promoted 3.1%+/-1.1% and 3.2%+/-1.1% cholesterol efflux from macrophages after isoflavone and placebo treatment, respectively. Thus, isoflavone supplementation did not affect ABCA1-dependent cholesterol efflux to serum. However, as a novel finding, isoflavone treatment increased a subclass of high-density lipoprotein, the pre-beta high-density lipoprotein levels by 18% without affecting any other serum lipid concentrations. ABCA1-facilitated cholesterol efflux and lipid parameters did not differ between equol-producing and non-equol-producing women.

CONCLUSION

In postmenopausal women, isolated isoflavone treatment does not affect ABCA1-dependent cholesterol efflux potential from macrophages but increases circulating pre-beta high-density lipoprotein level, which could provide beneficial vascular effects.

Soy diet worsens heart disease in mice

We report that dietary modification from a soy-based diet to a casein-based diet radically improves disease indicators and cardiac function in a transgenic mouse model of hypertrophic cardiomyopathy. On a soy diet, males with a mutation in the alpha-myosin heavy chain gene progress to dilation and heart failure. However, males fed a casein diet no longer deteriorate to severe, dilated cardiomyopathy. Remarkably, their LV size and contractile function are preserved. Further, this diet prevents a number of pathologic indicators in males, including fibrosis, induction of beta-myosin heavy chain, inactivation of glycogen synthase kinase 3beta (GSK3beta), and caspase-3 activation.