Potential health-modulating effects of isoflavones and metabolites via activation of PPAR and AhR

Flavonoids, Isoflavonoids and others Bioactives for Insulin Sensitizations

Diabetes is a chronic condition that has an impact on a huge part of the world. Both animals and humans have been demonstrated to benefit from natural goods, and organisms (animals, or microbes). In 2021, approximately 537 million adults (20-79 years) are living with diabetes, making it the one of the biggest cause of death worldwide. Various phytoconstituent preserved β- cells activity helps to prevent the formation of diabetes problems. As a result, β-cells mass and function are key pharmaceutical targets. The purpose of this review is to provide an overview of flavonoids' effects on pancreatic β-cells. Flavonoids have been demonstrated to improve insulin release in cell lines of isolated pancreatic islets and diabetic animal models. Flavonoids are thought to protect β-cells by inhibiting nuclear factor-κB (NF-κB) signaling, activating the phosphatidylinositol 3-kinase (PI3K) pathway, inhibiting nitric oxide production, and lowering reactive oxygen species levels. Flavonoids boost β-cells secretory capacity by improving mitochondrial bioenergetic function and increasing insulin secretion pathways. Some of the bioactive phytoconstituents such as S-methyl cysteine sulfoxides stimulate insulin synthesis in the body and increase pancreatic output. The berberine increased insulin secretion in the HIT-T15 and Insulinoma 6 (MIN6) mouse cell line. Epigallocatechin-3-Gallate protects against toxicity accrued by cytokines, reactive oxygen species (ROS), and hyperglycemia. Quercetin has been proven to boost insulin production by Insulinoma 1 (INS-1) cells and also protect cell apoptosis. Overall flavonoids have beneficial effects on β-cells by prevented their malfunctioning or degradation and improving synthesis or release of insulin from β-cells.

Loss of histone reader Phf7 leads to immune pathways activation via endogenous retroviruses during spermiogenesis

Genetic studies have elucidated the critical roles of Phf7 in germline development in animals; however, the exact etiology of Phf7 mutations leading to male infertility and the possibility of mechanism-based therapy are still unclear and warrant further investigation. Using the Phf7 knockout mouse model, we verified that genetic defects were responsible for male infertility by preventing histone-to-protamine exchange, as previously reported. The deficiency of spermatogenesis caused by Phf7 deletion through the endogenous retrovirus-mediated activation of the immune pathway is a common mechanism of infertility. Furthermore, we identified PPARα as a promising target of immunity and inflammation in the testis, where endogenous retroviruses are suppressed, and Phf7 as a crucial regulator of endogenous retrovirus-mediated immune regulation and revealed its role as an epigenetic reader. The loss of Phf7 activates immune pathways, which can be rescued by the PPARα agonist astaxanthin. These results showed that astaxanthin is a potential therapeutic agent for treating male infertility. The findings in our study provide insights into the molecular mechanisms underlying male infertility and suggest potential targets for future research and therapeutic development.

The great potential of flavonoids as candidate drugs for NAFLD

Non-alcoholic fatty liver disease (NAFLD) has a global prevalence of approximately 25 % and is associated with high morbidity and high mortality. NAFLD is a leading cause of cirrhosis and hepatocellular carcinoma. Its pathophysiology is complex and still poorly understood, and there are no drugs used in the clinic to specifically treat NAFLD. Its pathogenesis involves the accumulation of excess lipids in the liver, leading to lipid metabolism disorders and inflammation. Phytochemicals with the potential to prevent or treat excess lipid accumulation have recently received increasing attention, as they are potentially more suitable for long-term use than are traditional therapeutic compounds. In this review, we summarize the classification, biochemical properties, and biological functions of flavonoids and how they are used in the treatment of NAFLD. Highlighting the roles and pharmacological uses of these compounds will be of importance for enhancing the prevention and treatment of NAFLD.

Dietary regulation of peroxisome proliferator-activated receptors in metabolic syndrome

BACKGROUND

Peroxisome proliferator-activated receptors (PPARs) are a class of ligand-activated nuclear transcription factors, members of the type nuclear receptor superfamily, with three subtypes, namely PPARα, PPARβ/δ, and PPARγ, which play a key role in the metabolic syndrome. In the past decades, a large number of studies have shown that natural products can act by regulating metabolic pathways mediated by PPARs.

PURPOSE

This work summarizes the physiological importance and clinical significance of PPARs and reviews the experimental evidence that natural products mediate metabolic syndrome via PPARs.

METHODS

This study reviews relevant literature on clinical trials, epidemiology, animals, and cell cultures published in NCBI PubMed, Scopus, Web of Science, Google Scholar, and other databases from 2001 to October 2022. Search keywords were "natural product" OR "botanical" OR "phytochemical" AND "PPAR" as well as free text words.

RESULTS

The modulatory involvement of PPARs in the metabolic syndrome has been supported by prior research. It has been observed that many natural products can treat metabolic syndrome by altering PPARs. The majority of currently described natural compounds are mild PPAR-selective agonists with therapeutic effects that are equivalent to synthetic medicines but less harmful adverse effects.

CONCLUSION

PPAR agonists can be combined with natural products to treat and prevent metabolic syndrome. Further human investigations are required because it is unknown how natural products cause harm and how they might have negative impacts.

Isoflavone Protects the Renal Tissue of Diabetic Ovariectomized Rats via PPARγ

Diabetes associated with post-menopause is related to a worse condition of kidney disease. Taking into consideration that this disorder may be regulated by estrogenic mediators, we evaluated the renal protective effect of isoflavone. We investigated the role of the PPARγ in the pathogenesis of the disease. For this study, we used diabetic female rats in a postmenopausal model through ovariectomy. The animals were treated with isoflavone or 17β-estradiol. A dosage was administered to bring on blood glycemia, and through immunohistochemistry, we evaluated the immunoreactivity of PPARγ in the endometrium and renal tissue. We analyzed the immunoreactivity of renal injury molecule KIM-1 and the collagen and glycogen densities in the kidney. Through bioinformatics analysis, we observed PPARγ and COL1A1 gene expression under the influence of different glucose doses. In particular, we observed that isoflavone and 17β-estradiol regulate blood glycemia. Renal injury was inhibited by isoflavone, observed by a reduction in KIM-1, along with glycogen accumulation. These benefits of isoflavone may be associated with PPARγ overexpression in the kidneys and endometrium of diabetic ovariectomized rats.

A New Fungal Triterpene from the Fungus Aspergillus flavus Stimulates Glucose Uptake without Fat Accumulation

Through activity-guided fractionation, a new triterpene (asperflagin, 1) was isolated as a PPAR-γ agonist from the jellyfish-derived fungus Aspergillus flavus. Asperflagin displayed selective and moderate transactivation effects on PPAR-γ in Ac2F rat liver cells. Based on further biological evaluation and molecular docking analysis, we postulated that asperflagin might function as a PPAR-γ partial agonist. This compound was calculated to display a typical PPAR-γ ligand–receptor interaction that is distinct from that of full agonistic antidiabetics such as rosiglitazone, and may retain the antidiabetic effect without accompanying weight gain. Weight gain and obesity are typical side effects of the PPAR-γ full agonist rosiglitazone, and lead to suboptimal outcomes in diabetic patients. Compared to rosiglitazone, asperflagin showed higher glucose uptake in HepG2 human liver cells at concentrations of 20 and 40 μM but induced markedly lower adipogenesis and lipid accumulation in 3T3-L1 preadipocytes. These results suggest that asperflagin may be utilized for further study on advanced antidiabetic leads.

The Effects Of Tempe Extract On The Oxidative Stress Marker And Lung Pathology In Tuberculosis Wistar Rat

Background and Objective — Tempe (fermented soybean) has the potential as an affordable nutritional support alternative during tuberculosis (TB) infection. The purpose of the study was to assess the efficacy of supplementation with the ethanolic extract of Tempe on the oxidative stress markers alleviation and histological changes in male Wistar rats infected with Mycobacterium tuberculosis. Material and Methods — Thirty-five male Wistar rats were divided randomly into five groups and infected by Mycobacterium tuberculosis strain H37RV intratracheally. Total antioxidant capacity (TAC) and Thiobarbituric Acid Reaction (TBARS) levels were assessed using a colorimetric method while C-reactive protein (CRP) was measured by Elisa method. The lung damage was scored using histopathological parameters. Results — There were no significant differences in the TBARS levels and CRP concentrations compared to control. Tempe extract increased the TAC level at 200 (p=0.011), 400 (p=0.027), and 800 (p=0.029) kg/body weight concentrations compared to control. Perivasculitis and alveolitis mean scores were lower (p<0.05) than control in all supplement groups. Additionally, the mean scores of peribronchiolitis among supplementation groups were decreased (p<0.05) in the 200 and 800 mg/kg body weight, while the granuloma mean score was lower in the 800 mg/kg body weight compared to control. Conclusions — Tempe extract may have a weak efficacy in improving the antioxidant capacity and lung histological condition in TB rat models.

Exploring the Biological Activity and Mechanism of Xenoestrogens and Phytoestrogens in Cancers: Emerging Methods and Concepts

Xenoestrogens and phytoestrogens are referred to as "foreign estrogens" that are produced outside of the human body and have been shown to exert estrogen-like activity. Xenoestrogens are synthetic industrial chemicals, whereas phytoestrogens are chemicals present in the plant. Considering that these environmental estrogen mimics potentially promote hormone-related cancers, an understanding of how they interact with estrogenic pathways in human cells is crucial to resolve their possible impacts in cancer. Here, we conducted an extensive literature evaluation on the origins of these chemicals, emerging research techniques, updated molecular mechanisms, and ongoing clinical studies of estrogen mimics in human cancers. In this review, we describe new applications of patient-derived xenograft (PDX) models and single-cell RNA sequencing (scRNA-seq) techniques in shaping the current knowledge. At the molecular and cellular levels, we provide comprehensive and up-to-date insights into the mechanism of xenoestrogens and phytoestrogens in modulating the hallmarks of cancer. At the systemic level, we bring the emerging concept of window of susceptibility (WOS) into focus. WOS is the critical timing during the female lifespan that includes the prenatal, pubertal, pregnancy, and menopausal transition periods, during which the mammary glands are more sensitive to environmental exposures. Lastly, we reviewed 18 clinical trials on the application of phytoestrogens in the prevention or treatment of different cancers, conducted from 2002 to the present, and provide evidence-based perspectives on the clinical applications of phytoestrogens in cancers. Further research with carefully thought-through concepts and advanced methods on environmental estrogens will help to improve understanding for the identification of environmental influences, as well as provide novel mechanisms to guide the development of prevention and therapeutic approaches for human cancers.

Impact of the Association Between PNPLA3 Genetic Variation and Dietary Intake on the Risk of Significant Fibrosis in Patients With NAFLD

INTRODUCTION

This study explored the relationship between patatin-like phospholipase domain-containing 3 gene (PNPLA3 rs738409), nutrient intake, and liver histology severity in patients with nonalcoholic fatty liver disease (NAFLD).

METHODS

PNPLA3-rs738409 variant was genotyped in 452 non-Hispanic whites with histologically confirmed NAFLD who completed Food Frequency Questionnaire within 6 months of their liver biopsy. The fibrosis severity on liver histology was the outcome of interest.

RESULTS

The distribution of PNPLA3 genotypes was CC: 28%, CG: 46%, and GG: 25%. High-carbohydrate (% of energy/d) intake was positively associated (adjusted [Adj] odds ratio [OR]: 1.03, P < 0.01), whereas higher n-3 polyunsaturated fatty acids (n-3 PUFAs) (g/d) (Adj. OR: 0.17, P < 0.01), isoflavones (mg/d) (Adj. OR: 0.74, P = 0.049), methionine (mg/d) (Adj. OR: 0.32, P < 0.01), and choline (mg/d) (Adj. OR: 0.32, P < 0.01) intakes were inversely associated with increased risk of significant fibrosis (stage of fibrosis ≥2). By using an additive model of inheritance, our moderation analysis showed that PNPLA3 rs738409 significantly modulates the relationship between carbohydrate (%), n-3 PUFAs, total isoflavones, methionine, and choline intakes and fibrosis severity in a dose-dependent, genotype manner. These dietary factors tended to have a larger and significant effect on fibrosis severity among rs738409 G-allele carriers. Associations between significant fibrosis and carbohydrates (Adj. OR: 1.04, P = 0.019), n-3 PUFAs (Adj. OR: 0.16, P < 0.01), isoflavones (Adj. OR: 0.65, P = 0.025), methionine (Adj. OR: 0.30, P < 0.01), and total choline (Adj. OR: 0.29, P < 0.01) intakes remained significant only among rs738409 G-allele carriers.

DISCUSSION

This gene-diet interaction study suggests that PNPLA3 rs738409 G-allele might modulate the effect of specific dietary nutrients on risk of fibrosis in patients with NAFLD.

Regulation of Intestinal Inflammation by Soybean and Soy-Derived Compounds

Environmental factors, particularly diet, are considered central to the pathogenesis of the inflammatory bowel diseases (IBD), Crohn’s disease and ulcerative colitis. In particular, the Westernization of diet, characterized by high intake of animal protein, saturated fat, and refined carbohydrates, has been shown to contribute to the development and progression of IBD. During the last decade, soybean, as well as soy-derived bioactive compounds (e.g., isoflavones, phytosterols, Bowman-Birk inhibitors) have been increasingly investigated because of their anti-inflammatory properties in animal models of IBD. Herein we provide a scoping review of the most studied disease mechanisms associated with disease induction and progression in IBD rodent models after feeding of either the whole food or a bioactive present in soybean.

The phytoestrogen, quercetin, in serum, uterus and ovary as a potential treatment for dehydroepiandrosterone-induced polycystic ovary syndrome in the rat

The exact mechanisms of polycystic ovary syndrome (PCOS) are unknown and there is no effective cure for the disease. The aim of this study was to evaluate the alterations in serum oestradiol and adiponectin levels and in the expression of some important genes in the uterine and ovarian tissues of PCOS rats. The therapeutic effect of quercetin on PCOS was also assessed. Rats were divided into five groups: control, ethanol, quercetin (Q), PCOS and PCOS+Q. After 30 days of oral treatments, the rats' ovaries and uteri were removed and nesfatin-1, aromatase and adipoR1 expressions were quantified with real-time polymerase chain reaction. Serum adiponectin and oestradiol levels were evaluated using enzyme-linked immunosorbent assay technique. The results of this study showed that expression of nesfatin-1 and adipoR1 genes and adiponectin serum levels decreased in the PCOS rats, but aromatase expression and oestradiol level increased. Treatment with quercetin increased the adiponectin level and expression of adipoR1 and nesfatin-1 and decreased both the expression of aromatase and the oestradiol level. Quercetin improved PCOS by phytoestrogenic effects and mimicking oestrogen's function. Quercetin also affects important factors in both the uterus and ovary and could improve the obesity and the diabetic and infertility symptoms of PCOS.

Medicinal Potential of Isoflavonoids: Polyphenols That May Cure Diabetes

In recent years, there is emerging evidence that isoflavonoids, either dietary or obtained from traditional medicinal plants, could play an important role as a supplementary drug in the management of type 2 diabetes mellitus (T2DM) due to their reported pronounced biological effects in relation to multiple metabolic factors associated with diabetes. Hence, in this regard, we have comprehensively reviewed the potential biological effects of isoflavonoids, particularly biochanin A, genistein, daidzein, glycitein, and formononetin on metabolic disorders and long-term complications induced by T2DM in order to understand whether they can be future candidates as a safe antidiabetic agent. Based on in-depth in vitro and in vivo studies evaluations, isoflavonoids have been found to activate gene expression through the stimulation of peroxisome proliferator-activated receptors (PPARs) (α, γ), modulate carbohydrate metabolism, regulate hyperglycemia, induce dyslipidemia, lessen insulin resistance, and modify adipocyte differentiation and tissue metabolism. Moreover, these natural compounds have also been found to attenuate oxidative stress through the oxidative signaling process and inflammatory mechanism. Hence, isoflavonoids have been envisioned to be able to prevent and slow down the progression of long-term diabetes complications including cardiovascular disease, nephropathy, neuropathy, and retinopathy. Further thoroughgoing investigations in human clinical studies are strongly recommended to obtain the optimum and specific dose and regimen required for supplementation with isoflavonoids and derivatives in diabetic patients.

The possible antioxidant capabilities of formononetin in guarding against streptozotocin-induced diabetic nephropathy in rats

Background

Oxidative stress has been considered as a contributory aspect for major complications of diabetes mellitus consisting of diabetic nephropathy. This study aimed to examine the therapeutic effect of formononetin in streptozotocin (STZ)-induced diabetic nephropathy through measuring biochemical parameters, oxidative indicators, and histopathological examination of renal tissues.

Results

Administration of a dose of STZ (55 mg/kg of body weight) intraperitoneal induced diabetic nephropathy in rats as indicated by an increase in serum glucose, creatinine, triglyceride, cholesterol, and BUN levels related to the depletion of serum albumin level. Besides, STZ treatment led to the depletion of antioxidant enzymes together with superoxide dismutase (SOD), glutathione (GSH), and catalase (CAT). Administration of formononetin at the dose of 10, 20, and 40 mg/kg extensively decreased biochemical parameters with a rise in serum albumin level. Formononetin was observed to improved antioxidant enzyme ranges and offered protection against lipid peroxidation (LPO). STZ administered rats show an elevated level of TNF-α and IL-6. Meanwhile, formononetin-treated rats inhibited the elevated level of cytokine.

Conclusion

This study concluded that formononetin may additionally modulate oxidative stress and protected renal tissues from STZ injury. It also showed improvement in renal histopathological architecture in STZ-induced diabetic nephropathy.

Beneficial Effects of Isoflavones in the Kidney of Obese Rats Are Mediated by PPAR-Gamma Expression

Several studies have demonstrated an important association between altered lipid metabolism and the development of kidney injury because of a high-fat diet. Fructose is also closely associated with renal injury. We opted for a combination of fructose and saturated fats in a diet (DH) that is a model known to induce renal damage in order to evaluate whether soy isoflavones could have promising use in the treatment of renal alterations. After two months of ingestion, there was an expansion of visceral fat, which was associated with long-term metabolic disorders, such as sustained hyperglycemia, insulin resistance, polyuria, dyslipidemia, and hypertension. Additionally, we found a decrease in renal blood flow and an increase in renal vascular resistance. Biochemical markers of chronic kidney disease were detected; there was an infiltration of inflammatory cells with an elevated expression of proinflammatory cytokines (tumor necrosis factor-α, interleukin (IL)-6, and IL-1β), the activation of the renin–angiotensin system, and oxidative/nitrosative stress. Notably, in rats exposed to the DH diet for 120 days, the concomitant treatment with isoflavones after 60 days was able to revert metabolic parameters, renal alterations, and oxidative/nitrosative stress. The beneficial effects of isoflavones in the kidney of the obese rats were found to be mediated by expression of peroxisome proliferator-activated receptor gamma (PPAR-γ).

Genistin: A Novel Potent Anti-Adipogenic and Anti-Lipogenic Agent

Soy isoflavones are popular ingredients with anti-adipogenic and anti-lipogenic properties. The anti-adipogenic and anti-lipogenic properties of genistein are well-known, but those of genistin and glycitein remain unknown, and those of daidzein are characterized by contrasting data. Therefore, the purpose of our study was to investigate the effects of daidzein, glycitein, genistein, and genistin on adipogenesis and lipogenesis in 3T3-L1 cells. Proliferation of 3T3-L1 preadipocytes was unaffected by genistin and glycitein, but it was affected by 50 and 100 µM genistein and 100 µM daidzein for 48 h. Among the four isoflavones, only 50 and 100 µM genistin and genistein markedly suppressed lipid accumulation during adipogenesis in 3T3-L1 cells through a similar signaling pathway in a dose-dependent manner. Genistin and genistein suppress adipocyte-specific proteins and genes, such as peroxisome proliferator-activated receptor γ (PPARγ), CCAAT-enhancer-binding protein α (C/EBPα), and adipocyte binding protein 2 (aP2)/fatty acid-binding protein 4 (FABP4), and lipogenic enzymes such as ATP citrate lyase (ACL), acetyl-CoA carboxylase 1 (ACC1), and fatty acid synthase (FAS). Both isoflavones also activate AMP-activated protein kinase α (AMPKα), an essential factor in adipocyte differentiation, and inhibited sterol regulatory element-binding transcription factor 1c (SREBP-1c). These results indicate that genistin is a potent anti-adipogenic and anti-lipogenic agent.

Dual Function of a Novel Bacterium, Slackia sp. D-G6: Detoxifying Deoxynivalenol and Producing the Natural Estrogen Analogue, Equol

Deoxynivalenol (DON) is a highly abundant mycotoxin that exerts many adverse effects on humans and animals. Much effort has been made to control DON in the past, and bio-transformation has emerged as the most promising method. However, useful and effective application of bacterial bio-transformation for the purpose of inhibiting DON remains urgently needed. The current study isolated a novel DON detoxifying bacterium, Slackia sp. D-G6 (D-G6), from chicken intestines. D-G6 is a Gram-positive, non-sporulating bacterium, which ranges in size from 0.2–0.4 μm × 0.6–1.0 μm. D-G6 de-epoxidizes DON into a non-toxic form called DOM-1. Optimum conditions required for degradation of DON are 37–47 °C and a pH of 6–10 in WCA medium containing 50% chicken intestinal extract. Besides DON detoxification, D-G6 also produces equol (EQL) from daidzein (DZN), which shows high estrogenic activity, and prevents estrogen-dependent and age-related diseases effectively. Furthermore, the genome of D-G6 was sequenced and characterized. Thirteen genes that show potential for DON de-epoxidation were identified via comparative genomics. In conclusion, a novel bacterium that exhibits the dual function of detoxifying DON and producing the beneficial natural estrogen analogue, EQL, was identified.

Isoflavone daidzein regulates immune responses in the B6C3F1 and non-obese diabetic (NOD) mice

Daidzein (DAZ), a dominant isoflavone in various natural products such as soybeans, has been gaining attention due to the beneficial health effects (e.g., protection against cancer and diabetes) of its metabolites. Our major hypothesis was that dietary exposure to the soy phytoestrogen DAZ could modulate the immune responses toward a protective effect and lead to improved metabolic functions (such as glucose metabolism). In this study, we applied complementary mouse models, the hybrid B6C3F1 and inbred type 1 diabetes prone non-obese diabetic (NOD) mice, to investigate if DAZ exposure modulated the immune responses. The animals were orally administered DAZ at various physiological doses (2-20 mg/kg body weight) during adulthood. DAZ significantly altered the relative organ weights in female B6C3F1 mice and decreased the B cell population (represented by CD3-IgM+), while the T cell populations (represented by CD3+IgM-, CD4+CD8- and CD4-CD8+) were increased. In addition, DAZ dosing produced a decrease in the percentage of late apoptotic thymocytes. However, the activities cytotoxic T cells and natural killer cells were not altered in the B6C3F1 mice. In NOD mice, the blood glucose level and glucose tolerance were not affected by DAZ exposure, but DAZ modulated the antibody production, as shown by increased levels of IgG2b in NOD females and IgG1 in NOD males. Further, DAZ increased CD8+CD25+ splenocytes in NOD females. Taken together, DAZ induced an immunomodulatory effect in both NOD and B6C3F1 mouse strains; however, minimal effects on glucose homeostasis were observed.

A Possible Mechanism: Genistein Improves Metabolism and Induces White Fat Browning Through Modulating Hypothalamic Expression of Ucn3, Depp, and Stc1

Bioactive food components have gained growing attention in recent years. Multiple studies demonstrated that genistein had beneficial effects on metabolism. However, the exact mechanism by which genistein improves metabolism remains unclear, especially the central regulation. This study was designed to evaluate whether addition of genistein to the high-fat diet could counter metabolic disorders and whether these alterations were associated with gene expression in hypothalamus. C57BL/6 mice were fed either a high-fat diet (HF), high-fat diet with genistein (0.25 g/kg diet) (HFG) or a normal control diet (CON) for 8 weeks. Body weight was assessed during the study. After 8-week intervention, content of inguinal subcutaneous adipose tissue (SAT), perirenal visceral adipose tissue (VAT) and brown adipose tissue (BAT) were weighed. Glucose tolerance test, the serum levels of insulin and lipid were assessed. The mRNA of browning marker was detected in the white fat. The hypothalamus was collected for whole transcriptome sequencing and reverse transcription quantitative PCR validation. The results demonstrated that mice fed HFG diet had lower body weight and SAT mass, decrease levels of low-density lipoprotein cholesterol and free fatty acids, higher browning marker of Ucp1 and Cidea in WAT and an improvement in glucose tolerance and insulin sensitivity compared with those in HF group. Transcriptome sequencing showed that there were three differentially expressed genes in hypothalamus among the three groups, including Ucn3, Depp, and Stc1, which were significantly correlated with the browning markers in WAT and insulin sensitivity. Thus, regulating gene expressions in hypothalamus is a potential mechanism for genistein improving metabolism and inducing WAT browning, which may provide a novel target for the precaution and treatment of T2DM.

Polyphenols and Tryptophan Metabolites Activate the Aryl Hydrocarbon Receptor in an in vitro Model of Colonic Fermentation

Scope

Many dietary phytochemicals have been reported to promote gut health. Specific dietary phytochemicals, such as luteolin, as well as specific microbial metabolites of tryptophan are ligands of the aryl hydrocarbon receptor (AhR), which plays a role in immunity and homeostasis of the gut barrier. Here, the fate of luteolin during colonic fermentation and the contribution of tryptophan metabolites to AhR activity in different parts of the colon are investigated.

Methods and results

Several polyphenols are screened for AhR activation and oregano, containing the ligand luteolin, is added to batch cultures of human microbiota from the distal colon. Luteolin is rapidly metabolized, with no measurable increase in AhR activity. In the second experiment, using the Simulator of the Human Intestinal Microbial Ecosystem (SHIME), not all luteolin is metabolized in the ascending colon, but disappear rapidly in the transverse colon. The greatest AhR activity is due to microbiota‐derived metabolites of tryptophan, particularly in the descending colon.

Conclusions

Luteolin in food is rapidly metabolized in the transverse colon. Tryptophan metabolism by the microbiota in the colon contributes substantially to the pool of lumen metabolites that can activate the AhR.

Rebelling against the (Insulin) Resistance: A Review of the Proposed Insulin-Sensitizing Actions of Soybeans, Chickpeas, and Their Bioactive Compounds

Insulin resistance is a major risk factor for diseases such as type 2 diabetes and metabolic syndrome. Current methods for management of insulin resistance include pharmacological therapies and lifestyle modifications. Several clinical studies have shown that leguminous plants such as soybeans and pulses (dried beans, dried peas, chickpeas, lentils) are able to reduce insulin resistance and related type 2 diabetes parameters. However, to date, no one has summarized the evidence supporting a mechanism of action for soybeans and pulses that explains their ability to lower insulin resistance. While it is commonly assumed that the biological activities of soybeans and pulses are due to their antioxidant activities, these bioactive compounds may operate independent of their antioxidant properties and, thus, their ability to potentially improve insulin sensitivity via alternative mechanisms needs to be acknowledged. Based on published studies using in vivo and in vitro models representing insulin resistant states, the proposed mechanisms of action for insulin-sensitizing actions of soybeans, chickpeas, and their bioactive compounds include increasing glucose transporter-4 levels, inhibiting adipogenesis by down-regulating peroxisome proliferator-activated receptor-γ, reducing adiposity, positively affecting adipokines, and increasing short-chain fatty acid-producing bacteria in the gut. Therefore, this review will discuss the current evidence surrounding the proposed mechanisms of action for soybeans and certain pulses, and their bioactive compounds, to effectively reduce insulin resistance.

The associations between plasma phytoestrogens concentration and metabolic syndrome risks in Chinese population

Metabolic syndrome (MetS) has become an important issue in the healthcare systems of both developed and developing countries. Phytoestrogens have shown estrogenic effects, which may involve in the etiology of MetS. The current study consisted of 293 MetS cases and 264 healthy controls. The concentrations of seven plasma phytoestrogens (daidzein, genistein, glycitein, equol, enterolactone, enterodiol and coumestrol) were detected by UPLC-MS/MS. Adjusted unconditional logistic regression was used to assess the associations between plasma phytoestrogens concentration and risks of MetS, as well as the associations between plasma phytoestrogens concentration and MetS components. Linear regression was used to evaluate the associations between equol concentration in equol-producers and MetS components. Higher concentrations of total isoflavone and equol were associated with decreased risk of MetS. The equol concentration was negatively associated with waist circumference and positively associated with HDL-C level. Increased daidzein was associated with both lower waist circumference and lower fasting blood glucose levels. Our results suggested that higher plasma total isoflavone, equol and daidzein might decrease MetS risk.

The Potential and Action Mechanism of Polyphenols in the Treatment of Liver Diseases

Liver disease, involving a wide range of liver pathologies from fatty liver, hepatitis, and fibrosis to cirrhosis and hepatocellular carcinoma, is a serious health problem worldwide. In recent years, many natural foods and herbs with abundant phytochemicals have been proposed as health supplementation for patients with hepatic disorders. As an important category of phytochemicals, natural polyphenols have attracted increasing attention as potential agents for the prevention and treatment of liver diseases. The striking capacities in remitting oxidative stress, lipid metabolism, insulin resistance, and inflammation put polyphenols in the spotlight for the therapies of liver diseases. It has been reported that many polyphenols from a wide range of foods and herbs exert therapeutic effects on liver injuries via complicated mechanisms. Therefore, it is necessary to have a systematical review to sort out current researches to help better understand the potentials of polyphenols in liver diseases. In this review, we aim to summarize and update the existing evidence of natural polyphenols in the treatment of various liver diseases by in vitro, in vivo, and clinical studies, while special attention is paid to the action mechanisms.

4',6-Dimethoxyisoflavone-7-O-β-D-glucopyranoside (wistin) is a peroxisome proliferator-activated receptor α (PPARα) agonist in mouse hepatocytes

Peroxisome proliferator-activated receptors (PPARs) are ligand-dependent transcription factors that regulate lipid and glucose metabolism. PPARα mainly affects fatty acid metabolism, and its activation lowers lipid levels. PPARγ is involved in the regulation of adipogenesis, insulin sensitivity, energy balance, and lipid biosynthesis. We have previously reported that 4',6-dimethoxyisoflavone-7-O-β-D-glucopyranoside (wistin) can activate PPARγ. The purpose of the present study is to investigate the PPARα agonist activity of wistin. Using a luciferase reporter assay system of PPARα in monkey COS7 kidney cells, we showed that wistin could activate PPARα (P < 0.01 at 10 μg/mL) in a dose-dependent manner. Moreover, the addition of wistin upregulated the expression of PPARα (P < 0.01 at 10 μg/mL) and PPARα target genes including carnitine palmitoyltransferase 1a (P < 0.05 at 10 μg/mL), acyl-CoA oxidase (P < 0.01 at 10 μg/mL), acyl-CoA synthase (P < 0.05 at 10 μg/mL), PPARγ coactivator 1α (P < 0.05 at 10 μg/mL), uncoupling protein 2 (P < 0.05 at 1 μg/mL), and uncoupling protein 3 (P < 0.05 at 10 μg/mL), which are genes involved in lipid efflux and energy expenditure, in mouse primary hepatocytes. Furthermore, wistin inhibited cellular triglyceride accumulation in hepatocytes (P < 0.05 at 10 μg/mL) in a dose-dependent manner. These results indicate that wistin could suppress lipid accumulation through PPARα activation. The action of wistin on PPARα could be of interest for the amelioration of lipid metabolic disorders. To the best of our knowledge, wistin is the first reported isoflavonoid O-glycoside with PPARα agonist activity.

Flavonoids as Putative Inducers of the Transcription Factors Nrf2, FoxO, and PPARγ

Dietary flavonoids have been shown to extend the lifespan of some model organisms and may delay the onset of chronic ageing-related diseases. Mechanistically, the effects could be explained by the compounds scavenging free radicals or modulating signalling pathways. Transcription factors Nrf2, FoxO, and PPARγ possibly affect ageing by regulating stress response, adipogenesis, and insulin sensitivity. Using Hek-293 cells transfected with luciferase reporter constructs, we tested the potency of flavonoids from different subclasses (flavonols, flavones, flavanols, and isoflavones) to activate these transcription factors. Under cell-free conditions (ABTS and FRAP assays), we tested their free radical scavenging activities and used α-tocopherol and ascorbic acid as positive controls. Most of the tested flavonoids, but not the antioxidant vitamins, stimulated Nrf2-, FoxO-, and PPARγ-dependent promoter activities. Flavonoids activating Nrf2 also tended to induce a FoxO and PPARγ response. Interestingly, activation patterns of cellular stress response by flavonoids were not mirrored by their activities in ABTS and FRAP assays, which depended mostly on hydroxylation in the flavonoid B ring and, in some cases, extended that of the vitamins. In conclusion, the free radical scavenging properties of flavonoids do not predict whether these molecules can stimulate a cellular response linked to activation of longevity-associated transcription factors.

Oxidative Stress as a Critical Factor in Nonalcoholic Fatty Liver Disease Pathogenesis

SIGNIFICANCE

Nonalcoholic fatty liver disease (NAFLD), characterized by liver triacylglycerol build-up, has been growing in the global world in concert with the raised prevalence of cardiometabolic disorders, including obesity, diabetes, and hyperlipemia. Redox imbalance has been suggested to be highly relevant to NAFLD pathogenesis. Recent Advances: As a major health problem, NAFLD progresses to the more severe nonalcoholic steatohepatitis (NASH) condition and predisposes susceptible individuals to liver and cardiovascular disease. Although NAFLD represents the predominant cause of chronic liver disorders, the mechanisms of its development and progression remain incompletely understood, even if various scientific groups ascribed them to the occurrence of insulin resistance, dyslipidemia, inflammation, and apoptosis. Nevertheless, oxidative stress (OxS) more and more appears as the most important pathological event during NAFLD development and the hallmark between simple steatosis and NASH manifestation.

CRITICAL ISSUES

The purpose of this article is to summarize recent developments in the understanding of NAFLD, essentially focusing on OxS as a major pathogenetic mechanism. Various attempts to translate reactive oxygen species (ROS) scavenging by antioxidants into experimental and clinical studies have yielded mostly encouraging results.

FUTURE DIRECTIONS

Although augmented concentrations of ROS and faulty antioxidant defense have been associated to NAFLD and related complications, mechanisms of action and proofs of principle should be highlighted to support the causative role of OxS and to translate its concept into the clinic. Antioxid. Redox Signal. 26, 519-541.

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

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

Novel combination of sorafenib and biochanin-A synergistically enhances the anti-proliferative and pro-apoptotic effects on hepatocellular carcinoma cells

Sorafenib (SOR) is the first-line treatment for hepatocellular carcinoma (HCC). However, its use is hindered by the recently expressed safety concerns. One approach for reducing SOR toxicity is to use lower doses in combination with other less toxic agents. Biochanin-A (Bio-A), a promising isoflavone, showed selective toxicity to liver cancer cells. We postulated that combining SOR and Bio-A could be synergistically toxic towards HCC cells. We further evaluated the underlying mechanism. Cytotoxicity assay was performed to determine the IC₅₀ of Bio-A and SOR in HepG2, SNU-449 and Huh-7 cells. Then, combination index in HepG2 was evaluated using Calcusyn showing that the concurrent treatment with lower concentrations of SOR and Bio-A synergistically inhibited cell growth. Our combination induced significant arrest in pre-G and G0/G1 cell cycle phases and decrease in cyclin D1 protein level. Concomitantly, SOR/Bio-A reduced Bcl-2/Bax ratio. Furthermore, this co-treatment significantly increased caspase-3 & -9 apoptotic markers, while decreased anti-apoptotic and proliferative markers; survivin and Ki-67, respectively. Active caspase-3 in HepG2, SNU-449 and Huh-7 confirmed our synergism hypothesis. This study introduces a novel combination, where Bio-A synergistically enhanced the anti-proliferative and apoptotic effects of SOR in HCC cells, which could serve as a potential effective regimen for treatment.

Isoflavones: Anti-Inflammatory Benefit and Possible Caveats

Inflammation, a biological response of body tissues to harmful stimuli, is also known to be involved in a host of diseases, such as obesity, atherosclerosis, rheumatoid arthritis, and even cancer. Isoflavones are a class of flavonoids that exhibit antioxidant, anticancer, antimicrobial, and anti-inflammatory properties. Increasing evidence has highlighted the potential for isoflavones to prevent the chronic diseases in which inflammation plays a key role, though the underlying mechanisms remain unclear. Recently, some studies have raised concerns about isoflavones induced negative effects like carcinogenesis, thymic involution, and immunosuppression. Therefore, this review aims to summarize the anti-inflammatory effects of isoflavones, unravel the underlying mechanisms, and present the potential health risks.

4',6-dimethoxyisoflavone-7-O-β-D-glucopyranoside (wistin) is a peroxisome proliferator-activated receptor γ (PPARγ) agonist that stimulates adipocyte differentiation

Peroxisome proliferator-activated receptor γ (PPARγ) is a ligand-dependent transcription factor that directly activates the expression of adipocyte-specific genes, and is universally accepted as the master regulator for adipocyte differentiation. Using a PPARγ luciferase reporter assay system, we showed that 4',6-dimethoxyisoflavone-7-O-β-D-glucopyranoside (wistin) dose-dependently activates PPARγ. Treatment with wistin enhanced the marker of adipocyte differentiation, such as triglyceride accumulation in 3T3-L1 cells. Real-time quantitative polymerase chain reaction showed that wistin increased the expression of PPARγ2 messenger RNA. Moreover, the addition of wistin upregulated the expression of PPARγ-target genes, aP2 and adiponectin in 3T3-L1 cells. To our knowledge, wistin is the first isoflavonoid O-glycoside that exhibits PPARγ agonist activity.

Moderate Increase of Indoxyl Sulfate Promotes Monocyte Transition into Profibrotic Macrophages

OBJECTIVE

The uremic toxin Indoxyl-3-sulphate (IS), a ligand of Aryl hydrocarbon Receptor (AhR), raises in blood during early renal dysfunction as a consequence of tubular damage, which may be present even when eGFR is normal or only moderately reduced, and promotes cardiovascular damage and monocyte-macrophage activation. We previously found that patients with abdominal aortic aneurysms (AAAs) have higher CD14+CD16+ monocyte frequency and prevalence of moderate chronic kidney disease (CKD) than age-matched control subjects. Here we aimed to evaluate the IS levels in plasma from AAA patients and to investigate in vitro the effects of IS concentrations corresponding to mild-to-moderate CKD on monocyte polarization and macrophage differentiation.

METHODS

Free IS plasma levels, monocyte subsets and laboratory parameters were evaluated on blood from AAA patients and eGFR-matched controls. THP-1 monocytes, treated with IS 1, 10, 20 μM were evaluated for CD163 expression, AhR signaling and then induced to differentiate into macrophages by PMA. Their phenotype was evaluated both at the stage of semi-differentiated and fully differentiated macrophages. AAA and control sera were similarly used to treat THP-1 monocytes and the resulting macrophage phenotype was analyzed.

RESULTS

IS plasma concentration correlated positively with CD14+CD16+ monocytes and was increased in AAA patients. In THP-1 cells, IS promoted CD163 expression and transition to macrophages with hallmarks of classical (IL-6, CCL2, COX2) and alternative phenotype (IL-10, PPARγ, TGF-β, TIMP-1), via AhR/Nrf2 activation. Analogously, AAA sera induced differentiation of macrophages with enhanced IL-6, MCP1, TGF-β, PPARγ and TIMP-1 expression.

CONCLUSION

IS skews monocyte differentiation toward low-inflammatory, profibrotic macrophages and may contribute to sustain chronic inflammation and maladaptive vascular remodeling.

Isoflavones enhance interleukin-17 gene expression via retinoic acid receptor-related orphan receptors α and γ

The retinoic acid receptor-related orphan receptors α and γ (RORα and RORγ), are key regulators of helper T (Th)17 cell differentiation, which is involved in the innate immune system and autoimmune disorders. In this study, we investigated the effects of isoflavones on RORα/γ activity and the gene expression of interleukin (IL)-17, which mediates the function of Th17 cells. In doxycycline-inducible CHO stable cell lines, we found that four isoflavones, biochanin A (BA), genistein, formononetin, and daidzein, enhanced RORα- or RORγ-mediated transcriptional activity in a dose-dependent manner. In an activation assay of the Il17a promoter using Jurkat cells, these compounds enhanced the RORα- or RORγ-mediated activation of the Il17a promoter at concentrations of 1 × 10(-6)M to 1 × 10(-5)M. In mammalian two-hybrid assays, the four isoflavones enhanced the interaction between the RORα- or RORγ-ligand binding domain and the co-activator LXXLL peptide in a dose-dependent manner. In addition, these isoflavones potently enhanced Il17a mRNA expression in mouse T lymphoma EL4 cells treated with phorbol myristate acetate and ionomycin, but showed slight enhancement of Il17a gene expression in RORα/γ-knockdown EL4 cells. Immunoprecipitation and immunoblotting assays also revealed that BA enhanced the interaction between RORγt and SRC-1, which is a co-activator for nuclear receptors. Taken together, these results suggest that the isoflavones have the ability to enhance IL-17 gene expression by stabilizing the interactions between RORα/γ and co-activators. This also provides the first evidence that dietary chemicals can enhance IL-17 gene expression in immune cells.

Urinary phytoestrogens in relation to metabolic disturbances among children and adolescents

Previous studies have examined whether phytoestrogens affect glucose and lipid metabolism. However, data on children and adolescents are still limited, with most of the evidence pertaining to one phytoestrogen, namely genistein. To investigate the effect of six phytoestrogens [daidezin, enterodiol, enterolactone, equol, genistein and O-Desmethylangolensin (O-DMA)] on metabolic disturbances among youths, a cross-sectional study was conducted using a sample of 2,429 children and adolescents, 6-18 years, from the 2009-2010 National Health and Nutrition Examination Surveys (NHANES). The main outcome measures were body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure (DBP), high-density lipoprotein (HDL-C), low-density lipoprotein (LDL-C) and total cholesterol (TC), fasting glucose, triglycerides and glycohemoglobin. SBP was inversely related to enterolactone and equol. Triglycerides were inversely related to daidezin, equol, genistein and O-DMA. Whereas TC and LDL-C were inversely related to equol, an HDL-C was inversely related to genistein and O-DMA. Whereas fasting glucose was associated with enterodiol (β = 0.33, 95% CI: 0.028, 0.63), a positive relationship was observed between enterodiol and risk of HDL-C ≥ 35 mg dl(-1) (β = 0.04, 95% CI: 0.01, 0.07). In conclusion, certain phytoestrogens may contribute either positively or negatively to disturbances in lipid and glucose metabolism. Large prospective cohort studies are needed to confirm our study findings.

The effects of Cordyceps sinensis phytoestrogen on estrogen deficiency-induced osteoporosis in ovariectomized rats

BACKGROUND

Isoflavones are naturally occurring plant chemicals belonging to the "phytoestrogen" class. The aim of the present study was to examine the effects of isoflavones obtained from Cordyceps sinensis (CSIF) on development of estrogen deficiency-induced osteoporosis in ovariectomized rats.

METHODS

After the rats were treated orally with CSIF, serum alkaline phosphatase (ALP), tartarate resistant acid phosphatase (TRAP), serum osteocalcin (OC), homocysteine (HCY), C-terminal crosslinked telopeptides of collagen type I (CTX), estradiol and interferonγ (IFN-γ) level were examined. At the same time, the urine calcium, plasma calcium, plasma phosphorus and the mass of uterus, thymus and body were also examined.

RESULTS

The beneficial effects of CSIF on improvement of osteoporosis in rats were attributable mainly to decrease ALP activity, TRAP activity, CTX level and IFN-γ level. At the same time, CSIF also increase the OC and estradiol level in ovariectomized osteopenic rats. The histological examination clearly showed that dietary CSIF can prevent bone loss caused by estrogen deficiency.

CONCLUSION

The significant estrogenic activity of CSIF demonstrated that CSIF has significant estrogenic effects in OVX rats.

2-(2-Bromophenyl)-formononetin and 2-heptyl-formononetin are PPARγ partial agonists and reduce lipid accumulation in 3T3-L1 adipocytes

Isoflavones are bioactive compounds that have been shown to decrease lipid accumulation in vitro. However, the knowledge of the isoflavone formononetin is limited. The aim of the study was to assess the effects of formononetin and its two synthetic analogues, 2-(2-bromophenyl)-formononetin and 2-heptyl-formononetin, on lipid accumulation in 3T3-L1 adipocytes and investigate possible mechanisms. Formononetin and the two analogues were added day 0-8 or day 8-10 of the differentiation period, and lipid accumulation, glycerol release and gene expression were measured. Additionally, competitive peroxisome proliferator-activated receptor (PPAR)-γ binding assay, PPARγ transactivation assay and Western blot for phosphorylated AMP-activated protein kinase (AMPK) were performed. Chronic treatment (day 0-8) with formononetin increased lipid accumulation, whereas the two analogues decreased lipid accumulation partly due to decreased differentiation. The two analogues, but not formononetin, also decreased lipid content in mature adipocytes. 2-Heptyl-formononetin increased glycerol release and lipolytic gene expression and decreased lipogenic gene expression. Formononetin did not bind to or activate PPARγ whereas both analogues bound to the receptor and behaved as PPARγ partial agonists in the transactivation assay. Neither of the compounds affected phosphorylation of AMPK. In conclusion, the analogues of formononetin decreased lipid accumulation possibly in part by acting as PPARγ partial agonists.

Sub-chronically exposing mice to a polycyclic aromatic hydrocarbon increases lipid accumulation in their livers

The potential for exposing humans and wildlife to environmental polycyclic aromatic hydrocarbons (PAHs) has increased. Risk assessments describing how PAHs disturb lipid metabolism and induce hepatotoxicity have only received limited attention. In the present study, seven-week-old male ICR mice received intraperitoneal injections of 0, 0.01, 0.1 or 1mg/kg body weight 3-methylcholanthrene (3MC) per week for 10 weeks. A high-fat diet was provided during the exposure. Histopathological lipid accumulation and lipid metabolism-related genes were measured. We observed that sub-chronic 3MC exposure significantly increased lipid droplet and triacylglycerol (TG) levels in the livers. A low dose of 3MC activated the aryl hydrocarbon receptor, which negatively regulated lipid synthesis in the livers. The primary genes including acetyl-CoA carboxylase (Acc), fatty acid synthase (Fas) and stearoyl-CoA desaturase 1 (Scd1) decreased significantly when compared with those in the control group, indicating that de novo fatty acid synthesis in the hepatocytes was significantly inhibited by the sub-chronic 3MC exposure. However, the free fatty acid (FFA) synthesis in the adipose tissue was greatly enhanced by up-regulating the expression of peroxisome proliferator-activated receptor γ (PPARγ) and sterol regulatory element binding protein-1c (SREBP1C) and target genes including Acc, Fas and Scd1. The synthesized FFA was released into the blood and then transported into the liver by the up-regulation of Fat and Fatp2, which resulted in the gradual accumulation of lipids in the liver. In conclusion, histological examinations and molecular level analyses highlighted the development of lipid accumulation and confirmed that 3MC significantly impaired lipid metabolism in mice.

The beneficial effect of soybean (Glycine max (L.) Merr.) leaf extracts in adults with prediabetes: a randomized placebo controlled trial

The present study investigated the effects of soybean leaf extracts (SLEs) on blood glucose, insulin resistance, body fat and dyslipidemia in prediabetes subjects, and compared them with the effects of banaba extracts (BE) which is known to ameliorate diabetes in several animals and clinical studies. Overweight subjects with mild hyperglycemia (fasting blood glucose level of 100-125 mg dL(-1)) were randomly assigned to three groups and administered four capsules containing starch (2 g per day, Placebo), BE (300 mg per day, 0.3% corosolic acid) or SLE (2 g per day) during regular meals for 12 weeks. The SLE as well as BE significantly decreased the baseline-adjusted final blood glucose, HbA1c, HOMA-IR and transaminase levels compared to the placebo group. The body weight, BMI and WHR were not different between the groups, but the baseline-adjusted final body fat content and waist circumference were lower in the BE and SLE groups than in the placebo group. Furthermore, the baseline-adjusted final plasma triglyceride concentration was lower in the BE and SLE groups compared to the placebo group. There were no significant differences in plasma total cholesterol and LDL-cholesterol concentrations between the groups. However, the SLE, but not the BE, significantly increased the plasma HDL-cholesterol concentration and the ratio of HDL-cholesterol to total cholesterol after 12 weeks of supplementation compared to the placebo group, while the atherogenic index was decreased. Taken together, these data suggest that SLE may play an important role in improving blood glucose, insulin resistance, adiposity, and dyslipidemia in prediabetes subjects consuming their habitual diet, similar to or better than BE.

Genistein at maximal physiologic serum levels induces G0/G1 arrest in MCF-7 and HB4a cells, but not apoptosis

Several studies have demonstrated that a balanced diet can contribute to better human health. For this reason, soy-based food and pure isoflavones (pills) are one of the most consumed. The association of this consumption and lower risks of chronic diseases and cancer is well established for the Asian population and has been attracting the attention of people worldwide, especially women at menopause who seek to alleviate the symptoms associated with the lack of estrogen. Despite positive epidemiological data, concerns still exist because of conflicting results found in scientific literature with relation to the role of isoflavones in breast and hormone-related cancers. The aim of our study was to investigate the cytotoxicity, induction of apoptosis, and changes in apoptosis-related genes of maximal physiological serum levels of the isoflavone genistein (Gen) in MCF-7 tumoral cells and in HB4a non-tumoral cells. In addition, induction of cell cycle arrest was also investigated. Only supraphysiological levels of Gen (50 and 100 μM) were cytotoxic to these cell lines. Concentrations of 10 and 25 μM did not induce apoptosis and significant changes in expression of the studied genes. Positive results were found only in cell cycle analysis: G0/G1 delay of MCF-7 cells in both concentrations of Gen and at 25 μM in HB4a cells. It is the first study investigating effects of Gen in the HB4a cell line. Thus, despite the lack of apoptosis induction (generally found with high concentrations), Gen at physiologically relevant serum levels still exerts chemopreventive effects through the modulation of cell cycle.

Healthy aging diets other than the Mediterranean: a focus on the Okinawan diet

The traditional diet in Okinawa is anchored by root vegetables (principally sweet potatoes), green and yellow vegetables, soybean-based foods, and medicinal plants. Marine foods, lean meats, fruit, medicinal garnishes and spices, tea, alcohol are also moderately consumed. Many characteristics of the traditional Okinawan diet are shared with other healthy dietary patterns, including the traditional Mediterranean diet, DASH diet, and Portfolio diet. All these dietary patterns are associated with reduced risk for cardiovascular disease, among other age-associated diseases. Overall, the important shared features of these healthy dietary patterns include: high intake of unrefined carbohydrates, moderate protein intake with emphasis on vegetables/legumes, fish, and lean meats as sources, and a healthy fat profile (higher in mono/polyunsaturated fats, lower in saturated fat; rich in omega-3). The healthy fat intake is likely one mechanism for reducing inflammation, optimizing cholesterol, and other risk factors. Additionally, the lower caloric density of plant-rich diets results in lower caloric intake with concomitant high intake of phytonutrients and antioxidants. Other shared features include low glycemic load, less inflammation and oxidative stress, and potential modulation of aging-related biological pathways. This may reduce risk for chronic age-associated diseases and promote healthy aging and longevity.

Phytoestrogens and the metabolic syndrome

Phytoestrogens are a diverse class of non-steroidal compounds that have an affinity for estrogen receptors α and β, for the peroxisome proliferator-activated receptor (PPAR) family and for the aryl hydrocarbon receptor. Examples of phytoestrogens include prenylated flavonoids, isoflavones, coumestans and lignans. Many phytoestrogens counteract the cellular derailments that are responsible for the development of metabolic syndrome. Here we propose a mechanism of action which is based on five pillars/principles. First, phytoestrogens are involved in the downregulation of pro-inflammatory cytokines, such as COX-2 and iNOS, by activating PPAR and by inhibiting IκB activation. Second, they increase reverse cholesterol transport, which is mediated by PPARγ. Third, phytoestrogens increase insulin sensitivity, which is mediated via PPARα. Fourth, they exert antioxidant effects by activating antioxidant genes through KEAP. Fifth, phytoestrogens increase energy expenditure by affecting AMP-activated kinase signaling cascades, which are responsible for the inhibition of adipogenesis. In addition to these effects, which have been demonstrated in vivo and in clinical trials, other effects, such as eNOS activation, may also be important. Some plant extracts from soy, red clover or licorice can be described as panPPAR activators. Fetal programming for metabolic syndrome has been hypothesized; thus, the consumption of dietary phytoestrogens during pregnancy may be relevant. Extracts from soy, red clover or licorice oil have potential as plant-derived medicines that could be used to treat polycystic ovary syndrome, a disease linked to hyperandrogenism and obesity, although clinical trials have not yet been conducted. Phytoestrogens may help prevent metabolic syndrome, although intervention studies will be always be ambiguous, because physical activity and reduced calorie consumption also have a significant impact. Nevertheless, extracts rich in phytoestrogens may be an alternative treatment or may complement conventional treatment for diseases linked with metabolic syndrome. This article is part of a Special Issue entitled 'Phytoestrogens'.

Antidiabetic effects of chamomile flowers extract in obese mice through transcriptional stimulation of nutrient sensors of the peroxisome proliferator-activated receptor (PPAR) family

Given the significant increases in the incidence of metabolic diseases, efficient strategies for preventing and treating of these common disorders are urgently needed. This includes the development of phytopharmaceutical products or functional foods to prevent or cure metabolic diseases. Plant extracts from edible biomaterial provide a potential resource of structurally diverse molecules that can synergistically interfere with complex disorders. In this study we describe the safe application of ethanolic chamomile (Matricaria recutita) flowers extract (CFE) for the treatment and prevention of type 2 diabetes and associated disorders. We show in vitro that this extract activates in particular nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ) and its isotypes. In a cellular context, in human primary adipocytes CFE administration (300 µg/ml) led to specific expression of target genes of PPARγ, whereas in human hepatocytes CFE-induced we detected expression changes of genes that were regulated by PPARα. In vivo treatment of insulin-resistant high-fat diet (HFD)-fed C57BL/6 mice with CFE (200 mg/kg/d) for 6 weeks considerably reduced insulin resistance, glucose intolerance, plasma triacylglycerol, non-esterified fatty acids (NEFA) and LDL/VLDL cholesterol. Co-feeding of lean C57BL/6 mice a HFD with 200 mg/kg/d CFE for 20 weeks showed effective prevention of fatty liver formation and hepatic inflammation, indicating additionally hepatoprotective effects of the extract. Moreover, CFE treatment did not reveal side effects, which have otherwise been associated with strong synthetic PPAR-targeting molecules, such as weight gain, liver disorders, hemodilution or bone cell turnover. Taken together, modulation of PPARs and other factors by chamomile flowers extract has the potential to prevent or treat type 2 diabetes and related disorders.

The inhibitory effect of black soybean on hepatic cholesterol accumulation in high cholesterol and high fat diet-induced non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is defined as excess of fat in the liver. We investigated the effects of black soybean on the cholesterol metabolism and insulin resistance of mice fed high cholesterol/fat diets. Mice were randomly allocated into four groups that were fed different diets: the normal cholesterol/fat diet; high cholesterol/fat diets (HCD); and HCD with 1%, and 4% black soybean powder (1B-HCD, and 4B-HCD). Liver total cholesterol and triglyceride concentrations were significantly lower in the black soybean-supplemented groups than that in the HCD group. PCR revealed significantly lower hepatic SREBP2 and HMG-CoA reductase mRNA levels of black soybean-supplemented mice. Real-time PCR revealed significantly higher hepatic ABCA1 mRNA level of black soybean-supplemented mice, which may increase cholesterol efflux. Liver bile acids concentration was significantly high in the 4B-HCD group. Black soybean stimulated secretion of adiponectin, activation of pAMPK, and eliminated free fatty acids in the liver. Black soybean supplementation decreased MDA and nitrate level. The activities of SOD, catalase, and GPx were restored by black soybean supplementation. Our data strongly indicate that black soybean influences the balance between oxidative and antioxidative stress. We suggest that black soybean improves cholesterol metabolism, insulin resistance, and alleviates oxidative damage in NAFLD.

Overview of food products and dietary constituents with antidiabetic properties and their putative mechanisms of action: a natural approach to complement pharmacotherapy in the management of diabetes

Diabetes is one of the fastest growing chronic, noncommunicable diseases worldwide. Currently, 11 major classes of pharmacotherapy are available for the management of this metabolic disorder. However, the usage of these drugs is often associated with undesirable side effects, including weight gain and hypoglycemia. There is thus a need for new, safe and effective treatment strategies. Diet is known to play a major role in the prevention and management of diabetes. Numerous studies have reported the putative association of the consumption of specific food products, or their constituents, with the incidence of diabetes, and mounting evidence now suggests that some dietary factors can improve glycemic regulation. Foods and dietary constituents, similar to synthetic drugs, have been shown to modulate hormones, enzymes, and organ systems involved in carbohydrate metabolism. The present article reviews the major classes and modes of action of antidiabetic drugs, and examines the evidence on food products and dietary factors with antidiabetic properties as well as their plausible mechanisms of action. The findings suggest potential use of dietary constituents as a complementary approach to pharmacotherapy in the prevention and/or management of diabetes, but further research is necessary to identify the active components and evaluate their efficacy and safety.

Estrogen receptor-mediated effects of isoflavone supplementation were not observed in whole-genome gene expression profiles of peripheral blood mononuclear cells in postmenopausal, equol-producing women

Isoflavones (genistein, daidzein, and glycitein) are suggested to have benefits as well as risks for human health. Approximately one-third of the Western population is able to metabolize daidzein into the more potent metabolite equol. Having little endogenous estradiol, equol-producing postmenopausal women who use isoflavone supplements to relieve their menopausal symptoms could potentially be at high risk of adverse effects of isoflavone supplementation. The current trial aimed to study the effects of intake of an isoflavone supplement rich in daidzein compared with placebo on whole-genome gene expression profiles of peripheral blood mononuclear cells (PBMCs) in equol-producing, postmenopausal women. Thirty participants received an isoflavone supplement or a placebo for 8 wk each in a double-blind, randomized cross-over design. The isoflavone supplement was rich in daidzein (60%) and provided 94 mg isoflavones (aglycone equivalents) daily. Gene expression in PBMCs was significantly changed (P < 0.05) in 357 genes after the isoflavone intervention compared with placebo. Gene set enrichment analysis revealed downregulated clusters of gene sets involved in inflammation, oxidative phosphorylation, and cell cycle. The expression of estrogen receptor (ER) target genes and gene sets related to ER signaling were not significantly altered, which may be explained by the low ERα and ERβ expression in PBMCs. The observed downregulated gene sets point toward potential beneficial effects of isoflavone supplementation with respect to prevention of cancer and cardiovascular disease. However, whether ER-related effects of isoflavones are beneficial or harmful should be studied in tissues that express ERs.

Phytochemicals targeting genes relevant for type 2 diabetes

Nutrigenomic approaches based on ethnopharmacology and phytotherapy concepts have revealed that type 2 diabetes mellitus (T2DM) may be susceptible to dietary intervention. Interaction between bioactive food components and the genome may influence cell processes and modulate the onset and progression of the disease. T2DM, characterized by insulin resistance and beta cell dysfunction, is one of the leading causes of death and disability. Despite the great advances that have been made in the understanding and management of this complex, multifactorial disease, T2DM has become a worldwide epidemic in the 21st century. Population and family studies have revealed a strong genetic component of T2DM, and a number of candidate genes have been identified in humans. Variations in the gene sequences such as single nucleotide polymorphisms, explain the individual differences in traits like disease susceptibility and response to treatment. A clear understanding of how nutrients affect the expression of genes should facilitate the development of individualized intervention and, eventually, treatment strategies for T2DM. Review of the literature identified many phytochemicals/extracts from traditional medicinal plants that can target diabetogenic genes. This review focuses on the genetic aspects of T2DM, nutrient modification of genes relevant for diabetes, and future prospects of nutritional therapy of T2DM.

Nutraceuticals as Ligands of PPARγ

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated nuclear receptors that respond to several exogenous and endogenous ligands by modulating genes related to lipid, glucose, and insulin homeostasis. PPARγ, expressed in adipose tissue and liver, regulates lipid storage and glucose metabolism and is the target of type 2 diabetes drugs, thiazolidinediones (TZDs). Due to high levels of toxicity associated with the first generation TZDs, troglitazone (Rezulin), rosiglitazone (Avandia), and pioglitazone (Actos), there is a renewed search for newer PPAR drugs that exhibit better efficacy but lesser toxicity. In recent years, there has been a definite increase in the consumption of dietary supplements among diabetics, due to the possible health benefits associated with these nutraceutical components. With this impetus, investigations into alternative natural ligands of PPARs has also risen. This review highlights some of the dietary compounds (dietary lipids, isoflavones, and other flavanoids) that bind and transactivate PPARγ. A better understanding of the physiological effects of this PPAR activation by nutraceuticals and the availability of high-throughput technologies should lead to the discovery of less toxic alternatives to the PPAR drugs currently on the market.