High Levels Of Isoflavones Research Articles

Isoflavone profile identification and storage stability of different soybean genotypes sown at standard and late dates in a subtropical climate

The genetic variability of soybean grains allows its grow in different regions, where the adaptability of the genotypes to environments, and sowing times can affect the isoflavone profile and post-harvest conservation. Thus, the objective was to evaluate the genotype effects, sowing date, and storage time on technological properties and isoflavone profile of soybean. For this, it was used the soybean genotypes BMX LANÇA IPRO, NA 5909 RG, BMX ATIVA RR, and BMX GARRA IPRO, cultivated in standard (October 25th) and a late sowing date (November 15th). Analyzes performed in the present study were acidity, lipase activity, soluble protein, germination, electric conductivity, soybean defects, colorimetric profile, and isoflavone profile. Higher levels of isoflavones were found in the BMX GARRA IPRO genotype. The genotype BMX ATIVA RR when cultivated in late sowing date showed a reduced isoflavones contents. The NA 5909 RG genotype showed lower adaptability to the conditions of the environment where it was cultivated and higher susceptibility to prolonged storage, showing higher values of acidity, lipase activity, and lower values of soluble protein and germination. The BMX LANÇA IPRO genotype showed higher adaptability to the conditions of the environment where it was cultivated and to prolonged storage, showing higher values of soluble protein, and germination, and lower values of electrical conductivity, and soybean defects, proving the effect of genotype on soybean growing conditions. A reduction in soluble protein, germination, b*-value, and L*-value and an increase in acidity, lipase activity, electrical conductivity, and fermented grains during storage were observed.

Soy protein intake increased bone mineral density under nonenergy-deficiency conditions but decreased it under energy-deficiency conditions in young female rats

Many young individuals attempt to lose too much weight because of a false body image, which induces low bone mineral density (BMD) resulting from energy restriction. In addition, a decrease in estrogen has been observed along with the decrease in BMD. Estrogen is responsible for maintaining bone mass, and soybeans contain high levels of isoflavones, which have estrogen-like effects. Thus, we hypothesized that soy protein prevents low BMD caused by energy deficiency in young female rats. The purpose of this study was to examine the effect of soy protein intake on bone loss by energy deficiency in young female rats. Female Sprague-Dawley rats (6 weeks old) were randomly divided into the following 4 experimental groups: ad libitum feeding and casein diet (AL-Cas); ad libitum feeding and soy diet (AL-Soy); 40% energy restriction and casein diet (ER-Cas); and 40% energy restriction and soy diet (ER-Soy). The experimental period was 10.5 weeks. The AL-soy group had significantly higher BMD of the femur than the AL-Cas group (AL-Cas = 156 ± 5 mg/cm2, AL-Soy = 165 ± 7 mg/cm2; P < .05). Meanwhile, the ER-Soy group had significantly lower BMD of the tibia, femur, and lumbar spine than the ER-Cas group (ER-Cas = 147 ± 7 mg/cm2, ER-Soy = 133 ± 10 mg/cm2; P < .01). These results show that compared with ad libitum control groups, soy protein resulted in higher BMD under nonenergy deficiency, but under energy-deficiency conditions, it resulted in lower BMD.

Isoflavone malonyl-CoA acyltransferase GmMaT2 is involved in nodulation of soybean by modifying synthesis and secretion of isoflavones.

Malonyl-CoA:flavonoid acyltransferases (MaTs) modify isoflavones, but only a few have been characterized for activity and assigned to specific physiological processes. Legume roots exude isoflavone malonates into the rhizosphere, where they are hydrolyzed into isoflavone aglycones. Soybean GmMaT2 was highly expressed in seeds, root hairs, and nodules. GmMaT2 and GmMaT4 recombinant enzymes used isoflavone 7-O-glucosides as acceptors and malonyl-CoA as an acyl donor to generate isoflavone glucoside malonates. GmMaT2 had higher activity towards isoflavone glucosides than GmMaT4. Overexpression in hairy roots of GmMaT2 and GmMaT4 produced more malonyldaidzin, malonylgenistin, and malonylglycitin, and resulted in more nodules than control. However, only GmMaT2 knockdown (KD) hairy roots showed reduced levels of malonyldaidzin, malonylgenistin, and malonylglycitin, and, likewise, reduced nodule numbers. These were consistent with the up-regulation of only GmMaT2 by rhizobial infection, and higher expression levels of early nodulation genes in GmMaT2- and GmMaT4-overexpressing roots, but lower only in GmMaT2-KD roots compared with control roots. Higher malonyl isoflavonoid levels in transgenic hairy roots were associated with higher levels of isoflavones in root exudates and more nodules, and vice versa. We suggest that GmMaT2 participates in soybean nodulation by catalyzing isoflavone malonylation and affecting malonyl isoflavone secretion for activation of Nod factor and nodulation.

Abstract 4642: Effects of soy protein diet on plasma isoflavones levels in obese DMBA-induced mammary tumor rat model

Abstract Obesity epidemic in the US and world grows as the number of overweight and obese adults continues to rise. Obese women have higher mortality rates from all cancers including breast cancer. Several studies have reported the protective effects of soy intake on breast cancer development, while other studies report the adverse effects of soy protein diet on breast cancer development. Soybeans contain isoflavones genistein, daidzein and glycitein, known as isoflavonoids, which are structurally similar to mammalian estrogens, have estrogenic properties and are potential anticarcinogens. Gut flora metabolizes daidzein into equol, a non-steroidal estrogen and has cancer chemopreventive property. The objective of this study was to determine the effects of obesity and a high isoflavones soy protein diet on plasma isoflavones; genistein, daidzein, glycitein, equol and O-Desmethylangolensin (O-MDA) levels using 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary tumor model. Five-week-old female Zucker rats (45 obese fa/fa and 54 lean) were used. After one week of acclimation (age 42 days), rats were randomly assigned to the following diet groups; 1) Lean, casein; 2) Obese, casein; 3) Lean, soy and 4) Obese, soy. Rats had ad lib access to water and diet with either casein or soy protein isolate as source of protein. All rats were orally gavaged at age 50 days with 65 mg/kg DMBA. Rats were weighed and palpated twice weekly and sacrificed 21 weeks post-DMBA treatment. Plasma was collected to measure genistein, daidzein, glycitein, equol and O-MDA levels using liquid chromatography−tandem mass spectrometry (LC-MS/MS). At end of the experiment, 69% of the Lean casein rats developed mammary tumors compared to 50% in lean soy group (p= 0.176). In the obese group, 76% of the soy-fed rats developed mammary tumors compared to 15% (P&amp;lt;0.001) of obese casein- fed rats. Plasma daidzein and genistein concentration were not significantly different in lean vs obese soy-fed rats. However, O-MDA and equol concentration were significantly lower (P&amp;lt;0.05) in obese soy-fed rats compared to lean soy rats. These data suggests that obese rats fed soy protein diet containing high isoflavone levels promoted DMBA-induced mammary tumor development compared to a casein-based diet. Also, obese soy-fed rats exhibited significantly lower plasma equol concentrations than those observed in lean soy-fed rats and this reduction may aid in explaining soy's impaired cancer chemopreventative effects in obese breast cancer model. Citation Format: Reza Hakkak, Soheila Korourian. Effects of soy protein diet on plasma isoflavones levels in obese DMBA-induced mammary tumor rat model [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4642.

Soy noodles processed from soy flour or tofu affects antioxidant content, lipid accumulation in 3T3-L1 cells, and plasma lipids in hamsters

Nutritional properties of noodles prepared with soy flour (SN) or soy flour processed into tofu (TN) were compared to wheat noodles (WN) in vitro and in vivo using a hypercholesterolemic hamster model. SN and TN had higher levels of isoflavones, protein, fat, and dietary fiber, but lower levels of carbohydrate than WN. Predicted in vitro glycemic indices followed carbohydrate contents: WN, 88; SN, 30; and TN, 26. Lipid accumulation in 3 T3-L1 cells treated with an alcohol extract of TN was significantly (p < 0.05) lower than that treated alcohol extract of WN or SN. Hamsters fed a high fat diet supplemented with SN or TN had lower plasma total and LDL-cholesterol concentrations, body weight, and adipose weight than those fed a high fat diet supplemented with WN. Results of antioxidant capacity, in vitro glycemic and lipid accumulation, and animal feeding study showed that TN had higher nutritional value and bioactive potential than WN. Practical applications Thermal processing modifies nutritional values and functional properties of food with chemical changes. Soy based noodles were prepared from the same material using different processing methods: raw soy and heat-treated soy (tofu). Results of this study indicated that the soy based noodles showed greater bioactive capacity, leading to lower plasma total and LDL-cholesterol concentrations, less body weight, and less adipose weight than wheat noodles. Based on our results, tofu may be a better soy noodle ingredient than raw soy flour to improve health benefits of noodles.

Determination of in vitro isoflavone degradation in rumen fluid

The aim of this study was to determine the degradation of dietary isoflavones in rumen fluid under 2 feeding regimens. The experiments were performed in vitro using a rumen fluid buffer system. The rumen fluid was taken from cows fed either a hay diet or a concentrate-rich diet (the diet consisted of 34.6% maize silage, 17.6% haylage, 12.8% alfalfa hay, and 35.0% supplemental mixture on a dry matter basis). As a source of isoflavones, 40% soybean extract (Biomedica, Prague, Czech Republic) at levels of 5, 25, 50, and 75 mg per 40 mL of rumen fluid was used. Samples of soybean extract were incubated in triplicate at 39°C for 0, 3.0, 6.0, 12.0, and 24.0 h in incubation solution. The metabolism of daidzein and genistein was faster under concentrate-rich diet conditions. In general, production of equol started after 3 to 6 h of incubation and reached the highest rate after approximately 12 h of incubation regardless of the type of diet or concentration of extract. In most of the experiments, production of equol continued after 24 h of incubation. Generally, equol production was greater under the hay diet conditions. Furthermore, experiments with higher amounts of added soybean extract revealed possible inhibitory effects of high levels of isoflavones on the rumen microflora.

Isotrifoliol inhibits pro-inflammatory mediators by suppression of TLR/NF-κB and TLR/MAPK signaling in LPS-induced RAW264.7 cells

Soybeans, produced by Glycine max (L.) Merr., contain high levels of isoflavones, such as genistein and daidzein. However, soy leaves contain more diverse and abundant flavonol glycosides and coumestans, as compared to the soybean. This study investigated the anti-inflammatory effects of the major coumestans present in soy leaf (coumestrol, isotrifoliol, and phaseol) in lipopolysaccharide (LPS)-induced RAW264.7 cells. Coumestans significantly reduced LPS-induced nitric oxide (NO), prostaglandin E2 (PGE2), and reactive oxygen species (ROS) production; isotrifoliol had the most potent anti-inflammatory activity. Isotrifoliol reduced LPS-mediated induction of mRNA expression of inducible nitric-oxide synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin (IL)-1β, IL-6, tumor necrosis factor alpha (TNFα), and chemokines, such as chemokine (C-C motif) ligand (CCL) 2, CCL3, and CCL4. Isotrifoliol prevented NF-κB p65 subunit activation by reducing the phosphorylation and degradation of the inhibitor of NF-κB. And isotrifoliol significantly suppressed phosphorylation of the extracellular signal-regulated protein kinase 1/2 (ERK1/2) and p38 mitogen-activated protein kinase (MAPK). Furthermore, isotrifoliol suppressed LPS-induced Toll-like Receptor (TLR) signaling pathway, including mRNA expression of TNF receptor associated factor 6, transforming growth factor beta-activated kinase 1 (TAK1), TAK1 binding protein 2 (TAB2), and TAB3. These results demonstrate that isotrifoliol exerts an anti-inflammatory effect by suppressing the expression of inflammatory mediators via inhibition of TLR/NF-κB and TLR/MAPK signaling in LPS-induced RAW264.7 macrophages. Therefore, isotrifoliol can be used as an anti-inflammatory agent, and coumestan-rich soy leaf extracts may provide a useful dietary supplement.

Gene polymorphisms in the ornithine decarboxylase-polyamine pathway modify gastric cancer risk by interaction with isoflavone concentrations.

The study aimed to examine the association between genes encoding molecules in the ornithine decarboxylase (ODC)-polyamine pathway (ODC1, AMD1, NQO1, NOS2A, and OAZ2) and gastric cancer risk and whether the gene-phytoestrogen interaction modifies gastric cancer risk. Among 76 gastric cancer cases and their 1:4 matched controls within the Korean Multi-center Cancer Cohort, a total of 30 SNPs in five genes involved in the ODC pathway were primarily analyzed. The second-stage genotyping in 388 matched case-control sets was conducted to reevaluate the significant SNPs interacting with phytoestrogens during the primary analysis. The summary odds ratios (ORs) [95% confidence intervals (CIs)] for gastric cancer were estimated. Interaction effects between the SNPs and plasma concentrations of phytoestrogens (genistein, daidzein, equol, and enterolactone) were evaluated. In the pooled analysis, NQO1 rs1800566 showed significant genetic effects on gastric cancer without heterogeneity [OR0.83 (95% CI0.70-0.995)] and a greater decreased risk at high genistein/daidzein levels [OR0.36 (95% CI0.15-0.90) and OR0.26 (95% CI0.10-0.64), respectively; p interaction<0.05]. Risk alleles of AMD1 rs1279599, AMD1 rs7768897, and OAZ2 rs7403751 had a significant gene-phytoestrogen (genistein and daidzein) interaction effect to modify the development of gastric cancer. They had an increased gastric cancer risk at low isoflavone levels, but a decreased risk at high isoflavone levels (p interaction<0.01). Our findings suggest that common variants in the genes involved in the ODC pathway may contribute to the risk of gastric cancer possibly by modulating ODC polyamine biosynthesis or by interaction between isoflavones and NQO1, OAZ2, and AMD1.

Evaluations and Selections for High Isoflavone Black Soybean Mutants Induced by NaN&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt; Treatment

Sodium azide (NaN3) (2 mM) was used to induce mutation in black soybean variety CRWD for improvement of isoflavone content. The individual selections were made in M6, M7 and M8 generations, respectively. Both high levels of isoflavones and medium seed size traits were used as selection criteria. Across three growth seasons, the selected five NaN3-induced mutants accumulated more total isoflavones (average increases of 5% to 25%) than their wild type variety CRWD. Four mutants yielded more (average increases of 17% to 25%) than CRWD. Both mutants SA-M-03 (yellow cotyledon) and SA-M-05 (green cotyledon) are rich in isoflavones and may be useful in food and other applications.

Effects of phytoestrogen on sexual development

Phytoestrogen is an estrogenic compound that occurs naturally in plants. The most common sources of phytoestrogen are soybean products, which contain high levels of isoflavones. This compound, which has structural similarity with estrogen, can act as an estrogen receptor agonist or antagonist. Animal studies provide evidence of the significant effects of phytoestrogen on sexual development, including altered pubertal timing, impaired estrous cycling and ovarian function, and altered hypothalamus and pituitary functions. Although human studies examining the effects of phytoestrogen on sexual development are extremely limited, the results of some studies agree with those of the animal studies. In this paper, we review the possible mechanism of phytoestrogen action and the evidence showing the effects of phytoestrogen on sexual development in animal and human studies.

Application of an untargeted metabolomics approach for the identification of compounds that may be responsible for observed differential effects in chickens fed an organic and a conventional diet

The aim of this study was to apply an untargeted NMR and LC-MS-based metabolomics approach to detect potential differences between an organically and a conventionally produced feed, which caused statistically significant differences in growth, in the response to an immunological challenge and in the gene expression profiles in the small intestine of laying hens. A fractionation procedure was set up to create multiple fractions of the feed, which were subsequently analysed by NMR and UPLC-TOF/MS operating in positive mode. Comparison of the profiles revealed that the most apparent differences came from the isoflavones in the soy as well as a compound with a molecular mass of 441.202 (M + 1)+, which was identified as N,N′-diferuloylputrescine (DFP) and came from the corn. Whether the observed differences in effects are due to the higher levels of isoflavones and DFP is unclear, as is the fact whether the observed differences are typical for organic or conventional produced corn and soy. However, this study shows that this metabolomics approach is suitable for detecting potential differences between products, even in levels of compounds that would have been overlooked with a more targeted approach. As such, the method is suitable for a more systematic study on differences between conventionally and organically produced food.

Early-Life Soy Exposure and Gender-Role Play Behavior in Children

Background: Soy-based infant formula contains high levels of isoflavones. These estrogen-like compounds have been shown to induce changes in sexually dimorphic behaviors in animals exposed in early development.Objective: We examined gender-role play behavior in relation to soy-based and non-soy-based infant feeding methods among children in the Avon Longitudinal Study of Parents and Children.Methods: We studied 3,664 boys and 3,412 girls. Four exposure categories were created using data from questionnaires administered at 6 and 15 months postpartum: primarily breast, early formula (referent), early soy, and late soy. Gender-role play behavior was assessed using the Pre-School Activities Inventory (PSAI). Associations between infant feeding and PSAI scores at 42 months of age were assessed using linear regression. Post hoc analyses of PSAI scores at 30 and 57 months were also conducted.Results: Early-infancy soy use was reported for approximately 2% of participants. Mean [95% confidence interval (CI)] PSAI scores at 42 months were 62.3 (62.0, 62.6) and 36.9 (36.6, 37.2) for boys and girls, respectively. After adjustment, early soy (vs. early formula) feeding was associated with higher (less feminine) PSAI scores in girls (® = 2.66; 95% CI: 0.19, 5.12) but was not significantly associated with PSAI scores in boys. The association between soy exposure and PSAI scores in girls was substantially attenuated at 30 and 57 months.Conclusions: Although not consistent throughout childhood, early-life soy exposure was associated with less female-typical play behavior in girls at 42 months of age. Soy exposure was not significantly associated with play behavior in boys.

Effects of Light Treatment on Isoflavone Content of Germinated Soybean Seeds

Our research objective was to increase isoflavone content in the germinated soybean seeds of four different varieties (Pungsannamulkong, Cheongjakong, Aga4, and Aga3) by optimizing light treatments (dark, greenhouse, fluorescent, incandescent, and ultraviolet lamps). The results demonstrated that the highest isoflavone content was produced from the Aga3 variety, which was developed by an interspecific cross between Eunhakong (Glycine max) and KLG10084 (G. soja) at the Plant Genetic Laboratory, Kyunpook National University. Aga3 is known to have one of the highest isoflavone content in the world at present. Our results recommend exposure of 7-day-old Aga3 sprouts to a combined light treatment of greenhouse lamps (12 h per day) and ultraviolet light (40 min per day) for maximum isoflavone production. Aga3 produced high levels of isoflavone because, in part, it contained very high isoflavone levels within the seed as compared with the other varieties. Under stress conditions, Aga3 could produce over 1.90 times more isoflavone than its seed content and 1.53 times more isoflavone than when grown under dark conditions.

High isoflavone soy diet increases insulin secretion without decreasing insulin sensitivity in premenopausal nonhuman primates

Consuming soy and soy isoflavones has been shown to cause modest improvements in plasma lipids, lipoproteins, and indices of insulin sensitivity in postmenopausal women. The effect of soy on such end points is attributed often to estrogen receptor agonism by isoflavones. Recent in vitro studies suggest that isoflavones, in combination with high estrogen concentrations (within the range seen circulating in premenopausal women), function as estrogen receptor antagonists that potentially may counteract the beneficial effects seen with soy consumption. We studied insulin sensitivity in 15 premenopausal nonhuman primates consuming either a high isoflavone soy diet or a soy-free casein/lactalbumin diet for 4 months. Insulin sensitivity was measured by intravenous glucose tolerance testing, hyperinsulinemic-euglycemic clamps, and insulin-stimulated insulin receptor and protein kinase B phosphorylation levels in muscle. In addition, plasma lipids, adiponectin, thyroid hormone, and body weights are reported. We show that high isoflavones do not adversely affect insulin sensitivity but do significantly alter insulin secretion to glucose stimulation. Small but significant increases in thyroxine and increased high-density lipoprotein cholesterol were observed as has been reported commonly with soy intake. These study results demonstrate that consumption of soy containing high isoflavone levels is not associated with changes in insulin sensitivity in the high estrogen milieu of the premenopausal female.

Analysis of Isoflavones and Phenolic Compounds in Korean Soybean [Glycine max (L.) Merrill] Seeds of Different Seed Weights

The seeds of 322 Korean soybean varieties were collected from six different cultivated sites in Korea and classified into three groups based on the 100-seed weight as small, medium, and large. Seeds were analyzed for their concentrations of isoflavones and phenolic compounds. The total average isoflavones in soybean cultivated at Iksan (2.840 micromol g(-1)) and phenolic compounds in soybean grown at Yeoncheon (9.216 micromol g(-1)) and Iksan (9.154 micromol g(-1)) were significantly different (p<0.05). In small and medium seeds of soybeans cultivated at Yeoncheon, Yesan, and Milyang high levels of isoflavones were obtained, whereas soybeans grown in Chuncheon showed the lowest isoflavone concentrations. However, isoflavone concentrations in the large seeds of soybean cultivated at Chuncheon showed the highest level. The soybean cultivated at Yeoncheon had high levels of phenolic compounds in small, medium, and large seeds, whereas the soybean grown at Chuncheon had the lowest. On the other hand, the phenolic concentrations of large soybean cultivated at Milyang were the least. At Yeoncheon, Yesan, and Milyang, the total isoflavone and phenolic compounds levels related to their seed size was significantly different (p<0.05), whereas in the soybean of different sizes cultivated at Chuncheon, the relationship to their seed size was not significantly different. The relationships of total isoflavones and phenolic compounds of small and medium soybean seeds were significantly higher than that of large soybean seeds. The hydroxybenzoic acid group in all sizes of seeds cultivated at six sites in Korea was the major phenolic compound, followed by flavonoid and hydroxycinnamic acid. The total isoflavone concentration was positively correlated with acetylglycoside and negatively correlated with malonylglycoside in the small soybean seeds cultivated at Yeoncheon. In medium soybean seeds cultivated at Yeoncheon, a significantly positive correlation was found between acetylglycoside and glycoside, between aglycone and glycoside, and between aglycone and acetylglycoside, whereas a significantly negative correlation was shown between malonylglycoside and glycoside, between acetylglycoside and malonylglycoside, and between aglycone and malonylglycoside. In large soybean seeds cultivated at Chuncheon, significantly positive and negative correlations were similar to those of medium seeds. The results presented here can improve the understanding of the relationships among the concentrations of individual chemical compounds and each chemical compound group and total chemical compounds in soybeans of different seed sizes from different cultivated sites.

Isoflavones at Concentrations Present in Soy Infant Formula Inhibit Rotavirus Infection in Vitro ,

Rotavirus (RV) infections are a major cause of acute gastroenteritis in children and domestic animals, infecting virtually all children within their first 5 y of life. Infants consuming soy-based infant formula (SBIF) are exposed to high levels of isoflavones that exhibit antiviral activity on numerous viruses in vitro and in vivo. Thus, the hypothesis that isoflavones would inhibit RV infection was tested. All isoflavones at SBIF concentrations were tested individually and as a mixture (MIX). Virus infectivity was assessed in MA-104 cells using a focus forming unit assay. Genistin and MIX significantly reduced RV infectivity by 33–62% and 66–74%, respectively, compared with the control and across a wide range of RV concentrations. When tested without genistin, the MIX lost its anti-RV activity, suggesting that genistin is the biologically active isoflavone in our model. In a dose response assay, genistin significantly reduced RV infectivity at a concentration as low as 30 μmol/L. We investigated several possible mechanisms of action. Isoflavones decreased RV infectivity by modulating virion attachment to the host cells and by modulating a postbinding step. Isoflavones did not alter RV triple-layered structure and genistin did not act through inhibition of protein tyrosine kinases and topoisomerase II or by mimicking the effect of estrogens. To our knowledge, this is the first study showing the inhibition of RV infectivity by isoflavones present in SBIF. The modulation of SBIF isoflavone composition and concentration represents novel nutritional approaches to potentially reduce the severity of RV infection in human and production animals.

Effects of phytoestrogenic isoflavones from red clover (Trifolium pratense L.) on experimental osteoporosis

The most common type of osteoporosis is bone loss associated with ovarian hormone deficiency at menopause. There is evidence that diets which contain high levels of phytoestrogenic isoflavones are associated with a low incidence of osteoporosis and menopausal symptoms. Plant extracts, which contain high levels of isoflavones, such as Red clover (Trifolium pratense L.), have been used to reduce menopausal symptoms. The objective of this study was to evaluate the preventive effects of Red clover total isoflavones on the progression of bone loss induced by estrogens deficiency (ovariectomy) in rats. Bilateral ovariectomy was performed on female Wistar rats. One week after the operation the rats were treated with an oral dose of 20 and 40 mg of total isoflavones daily for 14 weeks. The results from this study showed that the ovariectomy reduced bone mineral content, femoral weight, femoral density, mechanical strength of the tibia and increased the levels of bone specific alkaline phosphatase in the serum and the number of osteoclasts in the femur sections compared with sham operated controls. Treatment with isoflavones significantly increased bone mineral content, mechanical strength of the tibia, femoral weight, femoral density and prevented the rise of serum alkaline phosphatase levels. In addition, the treatment with isoflavones significantly reduced the number of osteoclasts compared with the ovariectomized control rats. These findings suggest that Red clover isoflavones are effective in reducing bone loss induced by ovariectomy, probably by reducing of the bone turnover via inhibition of bone resorption.

Implications of Gene-Environment Interaction in Studies of Gene Variants in Breast Cancer: An Example of Dietary Isoflavones and the D356N Polymorphism in the Sex Hormone-Binding Globulin Gene

Studies to identify common genetic variants contributing to breast cancer risk often yield inconsistent results. Breast cancer is a complex disease involving both genetic and environmental determinants. Dietary isoflavones are thought to reduce breast cancer risk by stimulating circulating sex hormone-binding globulin (SHBG) levels. The SHBG gene contains a D356N polymorphism and the N variant is associated with reduced SHBG clearance compared with the D variant. In this study, we show a significant gene-environment interaction between SHBG D356N polymorphism and dietary isoflavone exposure on circulating SHBG levels in 1,988 postmenopausal women. SHBG levels were positively associated with isoflavones in women carrying the N variant (etap2 = 1.9%; P = 0.006) but not in women carrying only the D variant (etap2 = 0.0%; P = 0.999; P(interaction) = 0.019). This finding shows that the subtle effects of some genetic variants may be magnified and only become detectable in the presence of certain exposures. This gene-environment interaction might explain heterogeneity in studies associating SHBG gene variants and soy consumption with breast cancer risk in Far East population exposed to high isoflavone levels compared with populations with lower levels.

Effects of isoflavones from red clover (Trifolium pratense) on skin changes induced by ovariectomy in rats

Estrogens have a profound influence on skin. The relative hypoestrogenism that accompanies menopause exacerbates the deleterious effects of both intrinsic and environmental aging. Estrogens improve skin in many ways. Among these, they increase collagen content, skin thickness and improve skin moisture. There is evidence that diets with high levels of phytoestrogenic isoflavones are associated with a low incidence of menopausal symptoms and osteoporosis. Plant extracts such as red clover, which contain high levels of isoflavones, have been used to reduce menopausal symptoms and have been shown to reduce bone loss in healthy women. In this study to investigate the effects of red clover isoflavones on skin aging, the histology of the skin, skin thickness and the amount of total collagen determined by a colorimetric method, were studied in ovariectomized rats after treatment for 14 weeks with a red clover extract standardized to contain 11% isoflavones determined by HPLC. In ovariectomized rats the thickness and keratinization of the epidermis were reduced; glands were less in number and vascularity was poor; the distribution and morphology of the collagen bundles and elastic fibers were altered. Whereas the skin of the ovariectomized rats treated with red clover isoflavones (20 and 40 mg of total isoflavones daily for 14 weeks) appeared well organized with a normal epidermis with uniform thickness and regular keratinization; vascularity, collagen and elastic fibers were well developed. The amount of collagen significantly increased in the treated group in comparison with the control group. These findings suggest that red clover isoflavones are effective in reducing skin aging induced by estrogen deprivation.

Metabolic engineering to increase isoflavone biosynthesis in soybean seed

Isoflavone levels in Glycine max (soybean) were increased via metabolic engineering of the complex phenylpropanoid biosynthetic pathway. Phenylpropanoid pathway genes were activated by expression of the maize C1 and R transcription factors in soybean seed, which decreased genistein and increased the daidzein levels with a small overall increase in total isoflavone levels. Cosuppression of flavanone 3-hydroxylase to block the anthocyanin branch of the pathway, in conjunction with C1/R expression, resulted in higher levels of isoflavones. The combination of transcription factor-driven gene activation and suppression of a competing pathway provided a successful means of enhancing accumulation of isoflavones in soybean seed.