Antioxidant activity of phytoestrogenic isoflavones

Genistein modulates oxidative stress in breast cancer cell lines according to ERα/ERβ ratio: effects on mitochondrial functionality, sirtuins, uncoupling protein 2 and antioxidant enzymes

Genistein is a biologically active isoflavone with estrogenic activity and can be found in a variety of soy products. This natural compound displays a wide array of biological activities, but it is best known for its ability to inhibit cancer progression, especially for hormone-related ones such as breast cancer. Genistein has been shown to bind both the estrogen receptor alpha (ERα) and the estrogen receptor beta (ERβ), although it has a higher affinity for the ERβ. The ERα/ERβ ratio is a prognostic marker for breast tumors, and ERβ expression could indicate the presence of tumors more benign in state, whereas ERα indicates malignant tumors. The objective of the present study was to investigate the effects of genistein on oxidative stress and mitochondrial functionality through its interaction with the estrogen receptor in breast cancer cell lines with different ERα/ERβ ratios. The lower ERα/ERβ ratio T47D cell line showed lower oxidative stress and greater mitochondrial functionality, along with an up-regulation of uncoupling protein 2 and sirtuins. On the other hand, genistein-treated MCF-7 cell line, with the highest ERα/ERβ ratio, reported no changes for the control situation. On the whole, our results show different genistein effects depending on ERα/ERβ ratio for oxidative stress regulation, mitochondrial functionality, and modulation of UCPs, antioxidant enzymes and sirtuins in breast cancer cell lines. Effects of genistein on oxidative stress and mitochondria could be due at least in part, to a higher ERβ presence, but could also be due to up-regulation of ERβ caused by the genistein treatment.

Antioxidant function of isoflavone and 3,3'-diindolylmethane: are they important for cancer prevention and therapy?

SIGNIFICANCE

Oxidative stress has been mechanistically linked with aging and chronic diseases, including cancer. In fact, oxidative stress status, chronic disease-related inflammation, and cancer occurred in the aging population are tightly correlated. It is well known that the activation of nuclear factor kappa B (NF-κB) plays important roles in oxidative stress, inflammation, and carcinogenesis. Therefore, targeting NF-κB is an important preventive or therapeutic strategy against oxidative stress, inflammation, and cancer.

RECENT ADVANCES

A variety of natural compounds has been found to reduce oxidative stress through their antioxidant activity. Among them, isoflavone, indole-3-carbinol (I3C), and its in vivo dimeric compound 3,3'-diindolylmethane (DIM) have shown their promising effects on the inhibition of NF-κB with corresponding reduction of oxidative stress.

CRITICAL ISSUES

It has been found that isoflavone, I3C, and DIM could inhibit cancer development and progression by regulating multiple cellular signaling pathways that are related to oxidative stress and significantly deregulated in cancer.

FUTURE DIRECTIONS

The antioxidative and anticancer effects of these natural agents make them strong candidates for chemoprevention and/or therapy against human malignancies. However, more clinical trials are needed to evaluate the effects of isoflavone and DIM for the prevention of cancer development and also for the treatment of cancer either alone or in combination with conventional cancer therapeutics.

Comparative assessment of dermal wound healing potentials of various Trifolium L. extracts and determination of their isoflavone contents as potential active ingredients

ETHNOPHARMACOLOGICAL RELEVANCE

Trifolium species are used in Turkish folk medicine as a wound healing agent, expectorant, antiseptic, sedative and to alleviate pain in rheumatism. In the present study, the aqueous methanolic extracts (80%) of 13 Trifolium species (Trifolium ambigum, Trifolium arvense var. arvense, Trifolium campestre, Trifolium canescens, Trifolium hybridum var. anatolicum, Trifolium hybridum var. hybridum, Trifolium pannonicum, Trifolium pratense var. pratense, Trifolium purpureum var. purpureum, Trifolium repens var. repens, Trifolium resupinatum var. microcephalum, Trifolium spadiceum and Trifolium trichocephalum) collected from different regions of Anatolia were evaluated for their in vivo wound healing effects.

MATERIALS AND METHODS

In vivo wound healing activities of the plant aqueous methanolic extracts were evaluated by linear incision and circular excision wound models subsequent to histopathological analysis. Active constituents were determined by a validated high performance liquid chromatographic method. Precision of the method was performed by the evaluation of intra-day and inter-day variations of the each standard at limits of quantification (LOQ) levels.

RESULTS

The aqueous methanolic extracts of Trifolium canescens and Trifolium pretense var. pratense possessed better wound healing activity compared to the other extracts and control groups. The animal groups treated with the Trifolium canescens extract demonstrated increased contraction (48.96%) on excision and a significant increase in wound tensile strength (35.6%) on incision models. The main compounds were detected as genistein and biochanin A for Trifolium canescens.

CONCLUSION

The results of the present study revealed the wound healing potential of Trifolium canescens. This might be due to the combined effect of the isoflavones genistein, formononetin, daidzein, and biochanin A present in the extract.

Antioxidant properties of phytoestrogens

The oxidation of lipids is an autocatalytic process consisting of a number of well-defined interrelated chemical reactions. Its importance has long been recognized in the food and polymer industry, and recent advances in the understanding of vascular diseases have shown that lipid peroxidation also contributes to human disease. The various chemical stages of the reaction offer several therapeutic targets for inhibition, and from the structural characteristics of phytoestrogens it is anticipated that they should exhibit antioxidant properties. Alone, it is not sufficient for compounds such as the phytoestrogens to exhibit biological activity as antioxidants; the criteria that should be satisfied for this mechanism to be relevant biologically are discussed.

Synthesis of Resveratrol Glycosides by Cultured Plant Cells

Incubation of cultured cells of Glycine max with trans-resveratrol gave its 3-O-β-D- and 4′- O-β-D-glucosides. Cultured Gossypium hrsutum cells glycosylated trans-resveratrol to its 3-O-β-D-, 4′- O-β-D- and 3,4′- O-β-D-diglucosides. On the other hand trans-resveratrol was converted into cis-resveratrol 4′- O-β-D-glucoside together with trans-resveratrol 3- O-β-D-glucoside and trans-resveratrol 4′- O-β-D-glucoside by Eucalyptus perriniana.

Enhancing the antitumor cell proliferation and Cu(2+)-chelating effects of black soybeans through fermentation with Aspergillus awamori

In the present study, black soybeans were fermented with Aspergillus awamori at 30°C for 3 days. The effect of fermentation on the antiproliferative effect against human colon cancer cells, Caco-2 and HT-29 as well as Cu(2+)-chelating effect of black soybeans was investigated. It was found that the water, 80% methanol or 80% ethanol extract of fermented black soybeans showed a significantly higher (P < 0.05) antiproliferative and Cu(2+)-chelating effect than did the respective extract of non-fermented black soybeans. Generally, the methanol extract and the ethanol extract of fermented black soybeans exerted higher antiproliferative effect on both Caco-2 and HT-29 cells. While water extract of fermented black soybeans showed the highest Cu(2+)-chelating effect among the various extracts examined. Taking into account of extraction yields further revealed that bioactive principles that exhibit Cu(2+)-chelating effect could be extracted to the largest extent with water as the extraction solvent. With same amount of sample, water extract obtained from fermented black soybeans possesses the highest Cu(2+)-chelating abilities.

Functions and action mechanisms of flavonoids genistein and icariin in regulating bone remodeling

Increasingly natural products particularly flavonoids are being explored for their therapeutic potentials in reducing bone loss and maintaining bone health. This study has reviewed previous studies on the two better known flavonoids, genistein and icariin, their structures, functions, action mechanisms, relative potency, and potential application in regulating bone remodeling and preventing bone loss. Genistein, an isoflavone abundant in soy, has dual functions on bone cells, able to inhibit bone resorption activity of osteoclasts and stimulate osteogenic differentiation and maturation of bone marrow stromal progenitor cells (BMSCs) and osteoblasts. Genistein is an estrogen receptor (ER)-selective binding phytoestrogen, with a greater affinity to ERβ. Genistein inhibits tyrosine kinases and inhibits DNA topoisomerases I and II, and may act as an antioxidant. Genistein enhances osteoblastic differentiation and maturation by activation of ER, p38MAPK-Runx2, and NO/cGMP pathways, and it inhibits osteoclast formation and bone resorption through inducing osteoclastogenic inhibitor osteoprotegerin (OPG) and blocking NF-κB signaling. Icariin, a prenylated flavonol glycoside isolated from Epimedium herb, stimulates osteogenic differentiation of BMSCs and inhibits bone resorption activity of osteoclasts. Icariin, whose metabolites include icariside I, icariside II, icaritin, and desmethylicaritin, has no estrogenic activity. However, icariin is more potent than genistein in promoting osteogenic differentiation and maturation of osteoblasts. The existence of a prenyl group on C-8 of icariin molecular structure has been suggested to be the reason why icariin is more potent than genistein in osteogenic activity. Thus, the prenylflavonoids may represent a class of flavonoids with a higher osteogenic activity.

Anti-diabetic functions of soy isoflavone genistein: mechanisms underlying its effects on pancreatic β-cell function

Type 2 diabetes is a result of chronic insulin resistance and loss of functional pancreatic β-cell mass. Strategies to preserve β-cell mass and a greater understanding of the mechanisms underlying β-cell turnover are needed to prevent and treat this devastating disease. Genistein, a naturally occurring soy isoflavone, is reported to have numerous health benefits attributed to multiple biological functions. Over the past 10 years, numerous studies have demonstrated that genistein has anti-diabetic effects, in particular, direct effects on β-cell proliferation, glucose-stimulated insulin secretion and protection against apoptosis, independent of its functions as an estrogen receptor agonist, antioxidant, or tyrosine kinase inhibitor. Effects are structure-specific and not common to all flavonoids. While there are limited data on the effects of genistein consumption in humans with diabetes, there are a plethora of animal and cell-culture studies that demonstrate a direct effect of genistein on β-cells at physiologically relevant concentrations (<10 μM). The effects appear to involve cAMP/PKA signaling and there are some studies that suggest an effect on epigenetic regulation of gene expression. This review focuses on the anti-diabetic effects of genistein in both in vitro and in vivo models and potential mechanisms underlying its direct effects on β-cells.

Genistein: the potential for efficacy in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic, systemic inflammatory disorder that may affect many tissues and organs. Without treatment, inflammation leads to cartilage damage, bone erosions, joint destruction, and impaired movement. Because of the limited success of disease-modifying anti-rheumatic drugs, the exploration of new anti-rheumatic drugs with high efficacy and less toxicity is eagerly needed. Genistein, the major active compound from soybean, has received much attention due to its potential beneficial effects on some of the degenerative diseases. It has been found that genistein has anti-inflammatory, antiangiogenesis, antiproliferative, antioxidant, immunomodulatory, pain relief, and joint protection properties. Hence, significant advances have been made, both by in vitro and in vivo studies showing that genistein is a promising agent for RA treatment.

Health-Promoting Properties of Lactobacillus helveticus

Lactobacillus helveticus is an important industrial thermophilic starter that is predominantly employed in the fermentation of milk for the manufacture of several cheeses. In addition to its technological importance, a growing body of scientific evidence shows that strains belonging to the L. helveticus species have health-promoting properties. In this review, we synthesize the results of numerous primary literature papers concerning the ability of L. helveticus strains to positively influence human health. Several in vitro studies showed that L. helveticus possesses many common probiotic properties, such as the ability to survive gastrointestinal transit, adhere to epithelial cells, and antagonize pathogens. In vivo studies in murine models showed that L. helveticus could prevent gastrointestinal infections, enhance protection against pathogens, modulate host immune responses, and affect the composition of the intestinal microbiota. Interventional studies and clinical trials have also demonstrated a number of health-promoting properties of L. helveticus. Finally, several studies suggested that specific enzymatic activities of L. helveticus could indirectly benefit the human host by enhancing the bioavailability of nutrients, removing allergens and other undesired molecules from food, and producing bioactive peptides through the digestion of food proteins. In conclusion, this review demonstrates that in light of the scientific literature presented, L. helveticus can be included among the bacterial species that are generally considered to be probiotic.

Soyfoods and soybean products: from traditional use to modern applications

Soybean products (soyfoods), reported as potential functional foods, are implicated in several health-enhancing properties, such as easing the symptoms of postmenopausal women, reducing the risk of osteoporosis, preventing cardiovascular disease, and antimutagenic effects. Isoflavone, for example, is one of the most important compounds abundantly found in soybean, mainly accounting for the health-enhancing properties as mentioned earlier. However, most biological activities of isoflavones are mainly attributed to their aglycone forms. It has also been demonstrated that isoflavone aglycones are absorbed faster and in greater amount than their glycosides in human intestines. Fortunately, deglycosylation of isoflavones can be achieved during fermentation process by several strains such as lactic acid bacteria, basidiomycetes, filamentous fungus, and Bacillus subtilis with their β-glucosidase activity. This article presents an overview of soybean's chemistry, application, state-of-the-art advances in soybean fermentation processing and products as well as their applications in food and pharmaceutical industries. Different compounds, such as isoflavone, dietary fibers, and proteins which exhibit significant bioactivities, are summarized. The roles of different microorganisms in bioconversion and enhancement of bioactivities of fermented soybean are also discussed.

Glycosylation of trans-resveratrol by plant-cultured cells

Plant-cultured cells of Catharanthus roseus converted trans-resveratrol into its 3-O-β-D-glucopyranoside, 4'-O-β-D-glucopyranoside, 3-O-(6-O-β-D-xylopyranosyl)-β-D-glucopyranoside, and 3-O-(6-O-α-L-arabinopyranosyl)-β-D-glucopyranoside. The 3-O-(6-O-β-D-xylopyranosyl)-β-D-glucopyranoside and 3-O-(6-O-α-L-arabinopyranosyl)-β-D-glucopyranoside compounds of trans-resveratrol are both new. Incubation of plant-cultured cells of Ipomoea batatas and Strophanthus gratus with trans-resveratrol gave trans-resveratrol 3-O-β-D-glucopyranoside and trans-resveratrol 4'-O-β-D-glucopyranoside.

Genistein ameliorates hyperglycemia in a mouse model of nongenetic type 2 diabetes

While peripheral insulin resistance is common during obesity and aging in mice and people, the progression to type 2 diabetes (T2D) is largely due to loss of β-cell mass and function through apoptosis. We recently reported that genistein, a soy derived isoflavone, can improve glycemic control and β-cell function in insulin-deficient diabetic mice. However, whether it can prevent β-cell loss and diabetes in T2D mice is unknown. Our current study aimed to investigate the effect of dietary supplemented genistein in a nongenetic T2D mouse model. Nongenetic, middle-aged obese diabetic mice were generated by high fat diet and a low dose of streptozotocin injection. The effect of dietary supplementation of genistein on glycemic control and β-cell mass and function was determined. Dietary intake of genistein (250 mg·kg(-1) diet) improved hyperglycemia, glucose tolerance, and blood insulin level in obese diabetic mice, whereas it did not affect body weight gain, food intake, fat deposit, plasma lipid profile, and peripheral insulin sensitivity. Genistein increased the number of insulin-positive β-cell in islets, promoted islet β-cell survival, and preserved islet mass. In conclusion, dietary intake of genistein could prevent T2D via a direct protective action on β-cells without alteration of periphery insulin sensitivity.

Chemoprevention of prostate cancer: Natural compounds, antiandrogens, and antioxidants - In vivo evidence

Prostate cancer is the leading non-skin malignancy detected in US males and the second cause of death due to male cancer, in the US. Interventions with drugs or diet supplements that slow down the growth and progression of prostate cancer are potentially very effective in reducing the burden of prostate cancer, particularly if these treatments also prevent the de novo development of new prostatic malignancies. Challenges to identify efficacious agents and develop them for chemopreventive application in men at risk for prostate cancer have included uncertainty about which preclinical models have the ability to predict efficacy in men and lack of consensus about which early phase clinical trial designs are the most appropriate and cost-effective to test promising agents. Efficacy studies in animal models have identified several agents with potential chemopreventive activity against prostate cancer, but few of these findings have been translated into clinical trials. This article identifies some of the major issues associated with prostate cancer chemoprevention research and summarizes the most significant current results from animal efficacy studies and human clinical prevention trials. This summary focuses on: (1) Naturally occurring agents and compounds derived from such agents, including green tea and its constituents, silibinin and milk thistle, and genistein and soy, (2) chemoprevention drugs including agents interfering with androgen action, and (3) antioxidants such as selenium, vitamin E, and lycopene. The general lack of activity of antioxidants is discussed, followed by considerations about translation of preclinical chemoprevention efficacy data, focusing on dose, form, bioavailability, and timing of administration of the agent, as well as discussion of study design of clinical trials and the predictive ability of preclinical models.

Comparative effect of genistein and daidzein on the expression of MCP-1, eNOS, and cell adhesion molecules in TNF-α-stimulated HUVECs

We compared the effects of genistein and daidzein on the expression of chemokines, cell adhesion molecules (CAMs), and endothelial nitric oxide synthase (eNOS) in tumor necrosis factor (TNF)-α-stimulated human umbilical vascular endothelial cells (HUVECs). TNF-α exposure significantly increased expression of monocyte chemoattractant protein (MCP)-1, vascular adhesion molecule (VCAM)-1, and intercellular adhesion molecule-1. Genistein significantly decreased MCP-1 and VCAM-1 production in a dose-dependent manner, whereas CAM expression was not significantly lowered by genistein treatment. However, daidzein slightly decreased MCP-1 production. The effects of genistein and daidzein on MCP-1 secretion coincided with mRNA expression. Pre-treatment with either genistein or daidzein elevated eNOS expression and nitric oxide production disturbed by TNF-α exposure. A low concentration of isoflavones significantly inhibited nuclear factor (NF)κB activation, whereas a high dose slightly ameliorated these inhibitive effects. These results suggest that genistein had a stronger effect on MCP-1 and eNOS expression than that of daidzein. Additionally, NFκB transactivation might be partially related to the down-regulation of these mRNAs in TNF-α-stimulated HUVECs.

Novel soy germ pasta improves endothelial function, blood pressure, and oxidative stress in patients with type 2 diabetes

OBJECTIVE

To compare the effects of a novel soy germ-enriched pasta, containing isoflavone aglycons, with conventional pasta on endothelial function and cardiovascular risk markers in patients with type 2 diabetes (T2D).

RESEARCH DESIGN AND METHODS

This randomized controlled double-blind crossover study compared one serving/day of soy germ pasta and conventional pasta for 8 weeks for effects on brachial artery flow-mediated vasodilation, blood pressure, plasma lipids, oxidized LDL cholesterol, 8-iso-PGF2α, total antioxidant capacity (TAC), glutathione (GSH), and homocysteine.

RESULTS

Isoflavone-enriched pasta significantly improved arterial stiffness (P = 0.005) and reduced systolic (P = 0.026) and diastolic (P = 0.017) blood pressures. Plasma TAC increased (P = 0.0002), oxidized LDL cholesterol decreased (P = 0.009), 8-iso-PGF2α decreased (P = 0.001), GSH levels increased (P = 0.0003), and homocysteine decreased (P = 0.009) consistent with a reduction in oxidative stress. No significant changes were observed with conventional pasta.

CONCLUSIONS

Pasta enriched with biologically active isoflavone aglycons improved endothelial function and had beneficial effects on cardiovascular risk markers in patients with T2D.

Inhibition of airway inflammation, hyperresponsiveness and remodeling by soy isoflavone in a murine model of allergic asthma

Epidemiologic studies have associated higher dietary consumption of soy isoflavones with decreased self-report of cough and allergic respiratory symptoms, but the pharmacodynamic effects of soy isoflavone on asthmatic model have not been well-described. Here, we hypothesized that soy isoflavone may have potential effects on airway hyperresponsiveness, inflammation and airway remodeling in a murine of asthma. Mice sensitized and challenged with ovalbumin developed airway inflammation. Bronchoalveolar lavage fluid was assessed for inflammatory cell counts, and for cytokine levels. Lung tissues were examined for cell infiltration, mucus hypersecretion and airway remodeling, and for the expression of inflammatory biomarkers. Airway hyperresponsiveness was monitored by direct airway resistance analysis. Oral administration of soy isoflavone significantly reduced ovalbumin-induced airway hyperresponsiveness to intravenous methacholine, and inhibited ovalbumin-induced increases in eosinophil counts. RT-PCR analysis of whole lung lysates revealed that soy isoflavone markedly suppressed ovalbumin-induced mRNA expression of eotaxin, interleukin(IL)-5, IL-4 and matrix metalloproteinase-9, and increased mRNA expression of interferon (IFN)-γ and tissue inhibitor of metalloproteinase-1 in a dose-dependent manner. Soy isoflavone also substantially recovered IFN-γ/IL-4 (Th1/Th2) levels in bronchoalveolar lavage fluid. In addition, histologic studies showed that soy isoflavone dramatically inhibited ovalbumin-induced lung tissue eosinophil infiltration, airway mucus production and collagen deposition in lung tissues. Our findings suggest that soy isoflavone as nutritional supplement may provide a novel means for the treatment of airway inflammatory disease.

Resveratrol inhibits genistein-induced multi-drug resistance protein 2 (MRP2) expression in HepG2 cells

The interactions between various dietary cancer chemopreventive phytochemicals in drug transporter functions are not well studied. In this study, the effects of genistein and resveratrol on the multidrug resistance protein 2 (MRP2) expression and the underlying molecular mechanisms were investigated using HepG2-C3 cells that are stably transfected with a construct containing human MRP2 promoter region conjugated with luciferase reporter gene. A 3-fold induction of MRP2 luciferase activity was observed after genistein (50μM) treatment to HepG2-C3 cells, but was diminished by the resveratrol (50μM) cotreatment. This observation was further validated by Western blot analysis and RT-PCR analysis as resveratrol also inhibited genistein-induced MRP2 protein synthesis and mRNA expression. Immunofluorescence study revealed that genistein-induced formation of MRP2 vacuoles was dramatically reduced by resveratrol. The binding affinity between retinoid X receptor alpha (RXRα) and MRP2 promoter was examined by DNA-protein pull-down assay. The results showed that resveratrol inhibited the genistein-induced binding of RXRα to the promoter sequence of MRP2 gene, and this mechanism could potentially contribute to the inhibition of genistein-induced MRP2 expression by resveratrol. Taken together, our present study suggests that naturally occurring phytochemicals can potentially interfere with each other's regulatory function on the cancer chemoprevention-related genes through a competitive mechanism.

Fermentation with Aspergillus awamori enhanced contents of amino nitrogen and total phenolics as well as the low-density lipoprotein oxidation inhibitory activity of black soybeans

A solid fermentation was performed on black soybeans with Aspergillus awamori. The effects of fermentation on the contents of total phenolics and amino nitrogen and on the inhibitory effect on low-density lipoprotein (LDL) oxidation of black soybeans were examined. Results revealed that fermentation significantly enhanced the LDL oxidation inhibitory activity and total phenolics and amino nitrogen contents of black soybeans. The increased content of amino nitrogen was closely related to the enhanced LDL oxidation inhibitory activity of fermented black soybeans and its water extract. Fermentation temperature and length affected the LDL oxidation inhibitory effect exerted by the prepared fermented black soybeans. The A. awamori-fermented black soybean prepared at 30 °C for 3 days exhibited the highest inhibitory effect on LDL oxidation. The bioactive principles related to the inhibitory effect on LDL oxidation in black soybeans, regardless of fermentation, could be most efficiently extracted with water rather than 80% methanol or 80% ethanol.

Isoflavones and PPAR Signaling: A Critical Target in Cardiovascular, Metastatic, and Metabolic Disease

Isoflavone intake through foods and dietary supplements has both health advocates and critics. The latter come from a concern about the estrogenic effects of isoflavones in certain species. However, careful removal of isoflavones and other estrogens from the diet of rodents leads to the metabolic syndrome. These results suggest that isoflavones have other mechanisms of action, potentially those involving regulation of fatty acid metabolism via the nuclear receptors PPARα and PPARγ. The goal of this paper was to examine the evidence for isoflavone/PPAR signaling and to identify diseases in which such signaling would have an important impact. It is therefore of note that investigators using a chemical structure approach to discover PPAR ligands identified isoflavones as the best structures in the library of compounds that they tested. Future studies will involve careful identification of the underlying mechanisms whereby isoflavones have their action via PPAR signaling.

Soy isoflavones ameliorate the adverse effects of chemotherapy in children

Genistein sensitizes cancer cells to chemotherapy and radiation by modulating cell survival pathways. At the same time, genistein's antioxidant and anti-inflammatory effects may protect normal tissues from adverse effects of chemotherapy and radiation, which are largely due to oxygen-free radicals and inflammation. We conducted a small pilot study with a soy isoflavone mixture containing 8 mg of genistein in children receiving chemotherapy and/or radiation to investigate genistein's potential toxicity preventive effect. We monitored clinical and laboratory parameters in children with cancer who received their first cycle of chemotherapy without genistein and the subsequent cycles with genistein. Patients served as their own controls, and the clinical-laboratory data from the first cycle were compared to the data from subsequent cycles. Nine cycles of chemotherapy were administered without genistein and 57 cycles with genistein. Patients experienced less myelosuppression, mucositis, and infection when they received genistein with chemotherapy. During supplementation, serum genistein levels were 2 to 6 times higher compared to presupplementation levels. Patients who received abdominal radiation reported less pain and diarrhea when they took the genistein supplement. Further clinical investigation of soy isoflavones in pediatric cancer patients receiving chemotherapy and/or radiation should be conducted.

Genistein and daidzein, in combination, protect cellular integrity during 7,12-dimethylbenz[a]anthracene (DMBA) induced mammary carcinogenesis in Sprague-Dawley rats

The status of glycoconjugates (protein bound hexose, hexosamine, sialic acid and fucose) in plasma or serum serve as potential biomarkers for assessing tumor progression and therapeutic interventions. Aim of the present study was to investigate the protective effect of two major soy isoflavones, genistein and daidzein, in combination on the status of glycoconjugates in plasma, erythrocyte membrane and mammary tissues during 7,12-dimethylbenz[a]anthracene (DMBA) induced mammary carcinogenesis in female Sprague-Dawley rats. A single subcutaneous injection of DMBA (25 mg rat(-1)) in the mammary gland developed mammary carcinoma in female Sprague-Dawley rats. Elevated levels of plasma and mammary tissue glycoconjugates accompanied by reduction in erythrocyte membrane glycoconjugates were observed in rats bearing mammary tumors. Oral administration of genistein + daidzein (20 mg + 20 mg kg(-1) bw/day) to DMBA treated rats significantly (p< 0.05) brought back the status of glycoconjugates to near normal range. The present study thus demonstrated that genistein and daidzein in combination protected the structural integrity of the cell surface and membranes during DMBA-induced mammary carcinogenesis.

Dietary supplements and human health: for better or for worse?

Encouraged by the potential health benefits of higher dietary intake of substances with beneficial properties, the use of supplements containing these compounds has increased steadily over recent years. The effects of several of these, many of which are antioxidants, have been supported by data obtained in vitro, in animal models, and often by human studies as well. However, as carefully controlled human supplementation trials have been conducted, questions about the efficacy and safety of these supplements have emerged. In this Educational Paper, three different supplements were selected for consideration of the benefits and risks currently associated with their intake. The selected supplements include β-carotene, selenium, and genistein. The use of each is discussed in the context of preclinical and clinical data that provide evidence for both their use in reducing disease incidence and the possible liabilities that accompany their enhanced consumption. Variables that may influence their impact, such as lifestyle habits, baseline nutritional levels, and genetic makeup are considered and the application of these issues to broader classes of supplements is discussed.

Soybean supplementation helps reverse age- and scopolamine-induced memory deficits in mice

Phytoestrogens are nonsteroidal plant compounds that are able to exert estrogenic effects. Soybean is a rich source of phytoestrogens, especially isoflavones. Soy isoflavones are utilized for estrogen replacement therapy. Estrogen is reported to influence several areas of brain that are involved in cognition and behavior. Therefore, the present study was undertaken to examine whether dietary supplementation with soybean improves the cognitive function of mice. Soybean was administered in three different concentrations (2%, 5% and 10% [wt/wt]) in the normal diet to young and mature mice for 60 successive days. The passive avoidance paradigm and the elevated plus maze served as the exteroceptive behavioral models, whereas scopolamine (1.4 mg/kg, i.p.) served as the interoceptive behavioral model. The brain acetylcholinesterase activity (AChE) activity, brain thiobarbituric acid-reactive substances (TBARS), reduced glutathione (GSH), and total blood cholesterol levels were also measured in the present study. The administration of soybean for 60 consecutive days protected (P < .05) the animals from developing memory impairment. Soybean administration also resulted in diminished brain AChE activity, decrease in brain TBARS, and increase in GSH levels, thereby indicating facilitated cholinergic transmission, reduced free radical generation, and enhanced scavenging of free radicals. Thus, soybean appears to be a useful remedy for improving memory and for the management of cognitive deficits owing to its pro-estrogenic, antioxidant, procholinergic, and/or neuroprotective properties.

The pros and cons of phytoestrogens

Phytoestrogens are plant derived compounds found in a wide variety of foods, most notably soy. A litany of health benefits including a lowered risk of osteoporosis, heart disease, breast cancer, and menopausal symptoms, are frequently attributed to phytoestrogens but many are also considered endocrine disruptors, indicating that they have the potential to cause adverse health effects as well. Consequently, the question of whether or not phytoestrogens are beneficial or harmful to human health remains unresolved. The answer is likely complex and may depend on age, health status, and even the presence or absence of specific gut microflora. Clarity on this issue is needed because global consumption is rapidly increasing. Phytoestrogens are present in numerous dietary supplements and widely marketed as a natural alternative to estrogen replacement therapy. Soy infant formula now constitutes up to a third of the US market, and soy protein is now added to many processed foods. As weak estrogen agonists/antagonists with molecular and cellular properties similar to synthetic endocrine disruptors such as Bisphenol A (BPA), the phytoestrogens provide a useful model to comprehensively investigate the biological impact of endocrine disruptors in general. This review weighs the evidence for and against the purported health benefits and adverse effects of phytoestrogens.

Cardiac oxytocin receptor blockade stimulates adverse cardiac remodeling in ovariectomized spontaneously hypertensive rats

An increasing amount of evidence demonstrates the beneficial role of oxytocin (OT) in the cardiovascular system. Similar actions are attributed to genistein, an isoflavonic phytoestrogen. The treatment with genistein activates the OT system in the aorta of ovariectomized (OVX) Sprague-Dawley (SD) rats. The objective of this study was to determine the effects of low doses of genistein on the OT-induced effects in rat hypertension. The hypothesis tested was that treatment of OVX spontaneously hypertensive rats (SHRs) with genistein improves heart structure and heart work through a mechanism involving the specific OT receptor (OTR). OVX SHRs or SD rats were treated with genistein (in microg/g body wt sc, 10 days) in the presence or absence of an OT antagonist (OTA) [d(CH(2))(5), Tyr(Me)(2), Orn(8)]-vasotocin or a nonspecific estrogen receptor antagonist (ICI-182780). Vehicle-treated OVX rats served as controls. RT-PCR and Western blot analysis demonstrated that left ventricular (LV) OTR, downregulated by ovariectomy, increased in response to genistein. In SHRs or SD rats, this effect was blocked by OTA or ICI-182780 administration. The OTR was mainly localized in microvessels expressing the CD31 marker and colocalized with endothelial nitric oxide synthase. In SHRs, the genistein-stimulated OTR increases were associated with improved fractional shortening, decreased blood pressure (12 mmHg), decreased heart weight-to-body weight ratio, decreased fibrosis, and lowered brain natriuretic peptide in the LV. The prominent finding of the study is the detrimental effect of OTA treatment on the LV of SHRs. OTA treatment of OVX SHRs resulted in a dramatic worsening of ejection fractions and an augmented fibrosis. In conclusion, these results demonstrate that cardiac OTRs are involved in the regulation of cardiac function of OVX SHRs. The decreases of OTRs may contribute to cardiac pathology following menopause.

One-year soy protein supplementation does not improve lipid profile in postmenopausal women

OBJECTIVE

The risk of heart disease increases significantly in women after menopause mostly because of estrogen deficiency. Soy protein, a good source of isoflavones that are known to bind estrogen receptors, has also been promoted as a dietary means for reducing the risk of heart disease. The aim of this study was to examine the effects of soy protein consumption on heart disease risk in postmenopausal women.

METHODS

Moderately hypercholesterolemic postmenopausal women were randomly assigned to consume soy or control foods daily for 1 year. Serum samples were analyzed for total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, apolipoprotein (Apo) A, and Apo B. Sixty-two women completed the study.

RESULTS

There was a trend for total cholesterol and high-density lipoprotein cholesterol levels to increase after 1 year of soy protein supplementation (230.04 +/- 6.1 vs 242.57 +/- 6.2 mg/dL, P < 0.1, and 56.87 +/- 2.5 vs 60.33 +/- 2.5 mg/dL, P < 0.1, respectively). There were no significant differences in low-density lipoprotein cholesterol or triglyceride levels; however, a significant increase in Apo B levels (105.5 +/- 5.9 vs 120.21 +/- 5.9 mg/dL; P = 0.002) and a significant decrease in Apo A levels (189.36 +/- 10 vs 173.21 +/- 10 mg/dL; P = 0.009) were seen.

CONCLUSIONS

Our data indicate that 1-year soy protein supplementation did not confer cardiovascular benefits, in terms of favorable alterations in the lipid profile, in this cohort of postmenopausal women. These findings, as well as those from other studies, lend credence to the decision of the Food and Drug Administration to reevaluate the soy protein health claim issued a decade ago.

Genistein induces pancreatic beta-cell proliferation through activation of multiple signaling pathways and prevents insulin-deficient diabetes in mice

Genistein, a flavonoid in legumes and some herbal medicines, has various biological actions. However, studies on whether genistein has an effect on pancreatic beta-cell function are very limited. In the present study, we investigated the effect of genistein on beta-cell proliferation and cellular signaling related to this effect and further determined its antidiabetic potential in insulin-deficient diabetic mice. Genistein induced both INS1 and human islet beta-cell proliferation after 24 h of incubation, with 5 mum genistein inducing a maximal 27% increase. The effect of genistein on beta-cell proliferation was neither dependent on estrogen receptors nor shared by 17beta-estradiol or a host of structurally related flavonoid compounds. Pharmacological or molecular intervention of protein kinase A (PKA) or ERK1/2 completely abolished genistein-stimulated beta-cell proliferation, suggesting that both molecules are essential for genistein action. Consistent with its effect on cell proliferation, genistein induced cAMP/PKA signaling and subsequent phosphorylation of ERK1/2 in both INS1 cells and human islets. Furthermore, genistein induced protein expression of cyclin D1, a major cell-cycle regulator essential for beta-cell growth. Dietary intake of genistein significantly improved hyperglycemia, glucose tolerance, and blood insulin levels in streptozotocin-induced diabetic mice, concomitant with improved islet beta-cell proliferation, survival, and mass. These results demonstrate that genistein may be a natural antidiabetic agent by directly modulating pancreatic beta-cell function via activation of the cAMP/PKA-dependent ERK1/2 signaling pathway.

Neuroprotective effects of emodin in rat cortical neurons against beta-amyloid-induced neurotoxicity

Accumulation of beta-amyloid protein (Abeta) in the brain plays an important role in the pathogenesis of Alzheimer's disease (AD). In this study, the neuroprotective effect of emodin extracted from the traditional Chinese medicinal herb Polygonum cuspidatum Sieb. et Zucc against Abeta(25-35)-induced cell death in cultured cortical neurons was investigated. We found that pre-treatment with emodin prevented the cultured cortical neurons from beta-amyloid-induced toxicity. The preventive effect of emodin was blocked by pre-treatment with a phosphatidylinositol-3-kinase (PI3K) pathway inhibitor LY294002 or an estrogen receptor (ER) specific antagonist ICI182780, but not by pre-treatment with an extracellular signal-related kinases (ERK) inhibitor U0126. Furthermore, we found that emodin exposure induced the activation of the Akt serine/threonine kinase and increased the level of Bcl-2 expression. Moreover, the application of emodin for 24h was able to induce the activation of Abeta(25-35)-suppressed Akt and decrease the activation of the Jun-N-terminal kinases (JNK), but not of ERK. Interestingly, the up-regulation of Akt and Bcl-2 did not occur in the presence of LY294002 or ICI182780, suggesting that emodin-up-regulated Bcl-2 is mediated via the ER and PI3K/Akt pathway. Taken together, our results suggest that emodin is an effective neuroprotective drug and is a viable candidate for treating AD.

Genistein synergizes with arsenic trioxide to suppress human hepatocellular carcinoma

Arsenic trioxide (ATO) is of limited therapeutic benefit for the treatment of solid tumors. Genistein exhibits anticancer and pro-oxidant activities, making it a potential candidate to enhance the efficacy of ATO whose cytotoxicity is oxidation-sensitive. This study sought to determine whether genistein synergizes with ATO to combat hepatocellular carcinoma (HCC). Three human HCC cell lines, namely HepG2, Hep3B, and SK-Hep-1, were incubated with ATO, genistein, or ATO + genistein. The cells were also pretreated with antioxidant agents N-acetyl-L-cysteine (NAC) or butylated hydroxyanisole (BHA). Cell viability, apoptosis, intracellular reactive oxygen species (ROS), mitochondrial membrane potential (DeltaPsim), expression of Bcl-2, Bax, caspase-9, and -3, and release of cytochrome c into the cytosol were examined. The synergistic effect of ATO and genistein was also assessed using HepG2 xenografts subcutaneously established in BALB/c nude mice. The results show that genistein synergized with ATO to reduce viability, induce apoptosis, and diminish the DeltaPsim of cells. The combination therapy down-regulated Bcl-2 expression, up-regulated Bax expression, enhanced the activation of caspase-9 and -3, and increased the release of cytochrome c. The synergistic effect of ATO and genistein was diminished by pretreatment with NAC or BHA. Genistein increased the production of intracellular ROS, while ATO had little effect. Genistein synergized with a low dose of ATO (2.5 mg/kg) to significantly inhibit the growth of HepG2 tumors, and suppress cell proliferation and induce apoptosis in situ. There were no obvious side effects, as seen with a high dose of ATO (5 mg/kg). Combining genistein with ATO warrants investigation as a therapeutic strategy to combat HCC.

Isoflavones in coffee: influence of species, roast degree, and brewing method

This paper reports the isoflavone contents of roasted coffee beans and brews, as influenced by coffee species, roast degree, and brewing procedure. Total isoflavone level is 6-fold higher in robusta coffees than in arabica ones, mainly due to formononetin. During roasting, the content of isoflavones decreases, whereas their extractability increases (especially for formononetin). Total isoflavones in espresso coffee (30 mL) varied from approximately 40 microg (100% arabica) to approximately 285 microg (100% robusta), with long espressos (70 mL) attaining more than double isoflavones of short ones (20 mL). Espressos (30 mL) prepared from commercial blends contained average amounts of 6, 17, and 78 microg of genistein, daidzein, and formononetin, respectively. Comparison of different brewing methods revealed that espresso contained more isoflavones ( approximately 170 microg/30 mL) than a cup of press-pot coffee ( approximately 130 microg/60 mL), less than a mocha coffee ( approximately 360 microg/60 mL), and amounts similar to those of a filtered coffee cup ( approximately 180 microg/120 mL).

The response of creatine kinase specific activity in rat pituitary to estrogenic compounds and vitamin d less-calcemic analogs

We examined the response of rat female pituitary at different metabolic stages to treatments with estrogenic compounds and vitamin D analogs. Immature or ovariectomized (Ovx) female rats responded by increased creatine kinase specific activity (CK) to estradiol-17β (E₂), genistein (G), daidzein (D), biochainin A (BA), quecertin (Qu), carboxy- G (cG), carboxy- BA (cBA), and raloxifene (Ral). The response was inhibited when Ral was injected together with the estrogens. CK was increased when hormones were injected daily into Ovx rats for 4 different time periods. Pretreatment with the less-calcemic vitamin D analogs JK 1624 F₂-2 (JKF) or QW 1624 F₂-2 (QW) followed by estrogenic injection resulted in increased response and sensitivity to E₂ and loss of inhibition of E₂ by Ral. CK was also increased by feeding with E₂ or licorice or its components dose- and time- dependent in immature or Ovxrats. Diabetic female rats did not respond to increased doses of E₂. In conclusion, rat female pituitary is estrogens-responsive organ, suggesting to considerits response for HRT in postmenopausal women for both beneficial and hazardous aspects.

Analytical and compositional aspects of isoflavones in food and their biological effects

This paper provides an overview of analytical techniques used to determine isoflavones (IFs) in foods and biological fluids with main emphasis on sample preparation methods. Factors influencing the content of IFs in food including processing and natural variability are summarized and an insight into IF databases is given. Comparisons of dietary intake of IFs in Asian and Western populations, in special subgroups like vegetarians, vegans, and infants are made and our knowledge on their absorption, distribution, metabolism, and excretion by the human body is presented. The influences of the gut microflora, age, gender, background diet, food matrix, and the chemical nature of the IFs on the metabolism of IFs are described. Potential mechanisms by which IFs may exert their actions are reviewed, and genetic polymorphism as determinants of biological response to soy IFs is discussed. The effects of IFs on a range of health outcomes including atherosclerosis, breast, intestinal, and prostate cancers, menopausal symptoms, bone health, and cognition are reviewed on the basis of the available in vitro, in vivo animal and human data.

Effects of phyto-oestrogens on tissues

Recent investigations on the effects of phyto-oestrogens on various tissues have revealed that these diverse molecules may improve human health, particularly by protecting against certain chronic diseases. After a brief examination of the food sources, structures, and general cellular actions of the major phyto-oestrogens, current research findings on cardiovascular disease, skeletal tissues, and reproductive cancers are reviewed. Phyto-oestrogen concentrations in blood may be maintained at high levels in those consuming soyabean (Glycine max)-based food daily at several meals and exert their effects on target cells through either genomic effects via the classical oestrogen receptors or non-genomic effects mediated by membrane-bound oestrogen receptors or other cellular proteins. The expression of oestrogen receptor (OR) subtypes alpha (a) and beta (beta) varies across tissues, and cells that preferentially express OR-beta, which may include bone cells, are more likely to respond to phyto-oestrogens. Conversely, reproductive tissues contain relatively more OR-a and may, thus, be differently affected by phyto-oestrogens. Soyabean phyto-oestrogens appear to prevent the progression of atherosclerosis through multiple interactions, including lowering of plasma lipids and lipoproteins, increased vasodilatation and, possibly, decreased activation of blood platelets and vascular smooth muscle cells. However, a favourable impact on cardiovascular disease morbidity and mortality by a soyabean-enriched western-type diet remains to be shown, and unresolved questions remain regarding dose and form of the phyto-oestrogens in relation to risks and benefits. The isoflavones of soyabean have been shown consistently to have bone-retentive effects in animal studies by several investigators using rodent models, although intakes must be above a relatively high threshold level for a lengthy period of time, and little or no extra benefit is observed with intakes above this threshold level. The reports of modest or no effects on prevention of bone loss in human and non-human primate studies respectively, may be due to the limited doses tested so far. The relationship between soyabean-food intake and cancer risk has been more extensively investigated than for any other disease, but with less certainty about the benefits of long-term consumption of phyto-oestrogen-containing foods on prevention of cancer. The observations that breast and prostate cancer rates are lower in Asian countries, where soyabean foods are consumed at high levels, and the high isoflavone content of soyabeans have led to examination of the potential protective effects of phyto-oestrogens. Establishing diet-cancer relationships has proved difficult, in part because of the conflicting data from various studies of effects of soyabean-diets on cancer. Epidemiological evidence, though not impressive, does suggest that soyabean intake reduces breast cancer risk. The isoflavone genistein has a potent effect on breast cancer cells in vitro, and early exposure of animals to genistein has been effective in reducing later development of mammary cancer. Thus, continuous consumption of soyabean foods in early life and adulthood may help explain the low breast cancer mortality rates in Asian countries. Although the evidence for a protective effect against prostate cancer may be slightly more supportive, more research is needed before any firm conclusions can be made about the phyto-oestrogen-cancer linkages.