Genistein prevents hyperglycemia-induced monocyte adhesion to human aortic endothelial cells through preservation of the cAMP signaling pathway and ameliorates vascular inflammation in obese diabetic mice

Long-term supplementation of genistein improves immune homeostasis in the aged gut and extends the laying cycle of aged laying hens

Aging is associated with alterations in gut function, including intestinal inflammation, leaky gut, and impaired epithelial regeneration. Rejuvenating the aged gut is imperative to extend the laying cycle of aged laying hens. Genistein is known to have beneficial effects on age-related diseases, but its precise role in homeostasis of the aged gut of laying hens remains to be elucidated. In this study, 160 45-wk-old Hyline Brown laying hens were continuously fed a basal diet or a diet supplemented with 40 mg/kg genistein until they reached 100 wk of age. The results revealed that long-term genistein supplementation led to an improvement in the egg production rate and feed conversion ratio, as well as an increase in egg quality. Moreover, the expression levels of senescence markers, such as β-galactosidase, P16, and P21, were decreased in the gut of genistein-treated aged laying hens. Furthermore, genistein ameliorated gut dysfunctions, such as intestinal inflammation, leaky gut, and impaired epithelial regeneration. Treg cell-derived IL-10 plays a crucial role in the genistein-induced regulation of age-related intestinal inflammation. This study demonstrates that long-term consumption of genistein improves homeostasis in the aged gut and extends the laying cycle of aged laying hens. Moreover, the link between genistein and Treg cells provides a rationale for dietary intervention against age-associated gut dysfunction.

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.

In-silico, in-vitro and in-vivo Biological Activities of Flavonoids for the Management of Type 2 Diabetes

In spite of the fact that many medicinal plants have been truly utilized for the management of diabetes all through the world, very few of them have been reported scientifically. Recently, a diverse variety of animal models have been established to better understand the pathophysiology of diabetes mellitus, and new medications to treat the condition have been introduced in the market. Flavonoids are naturally occurring substances that can be found in plants and various foods and may have health benefits in the treatment of neuropathic pain. Flavonoids have also been shown to have an anti-inflammatory impact that is significant to neuropathic pain, as indicated by a decrease in several pro-inflammatory mediators such TNF-, NF-B IL-6, and IL-1. Flavonoids appear to be a viable novel therapy option for macrovasular complications in preclinical models; however, human clinical data is still inadequate. Recently, several in silico, in-vitro and in-vivo aproaches were made to evaluate mechanisms associated with the pathogenesis of diabetes in a better way. Screening of natural antidiabetic agents from plant sources can be analysed by utilizing advanced in-vitro techniques and animal models. Natural compounds, mostly derived from plants, have been studied in diabetes models generated by chemical agents in the majority of research. The aim of this work was to review the available in silico, in-vitro and animal models of diabetes for screening of natural antidiabetic agents. This review contributes to the scientist's design of new methodologies for the development of novel therapeutic agents having potential antihyperglycemic activity.

Underlying mechanisms and molecular targets of genistein in the management of type 2 diabetes mellitus and related complications

Diabetes mellitus (DM) is a chronic metabolic disease caused by a complex interaction of genetic and environmental factors and is characterized by persistent hyperglycemia. Long-term hyperglycemia can cause macrovascular and microvascular damage, and compromise the heart, brain, kidney, peripheral nerves, eyes and other organs, leading to serious complications. Genistein, a phytoestrogen derived from soybean, is known for its various biological activities and therapeutic properties. Recent studies found that genistein not only has hypoglycemic activity but can also decrease insulin resistance. In addition, genistein has particular activity in the prevention and treatment of diabetic complications, such as nephropathy, cardiovascular disease, osteoarthrosis, encephalopathy and retinopathy. Therefore, the purpose of this review is to summarize the latest medical research and progress of genistein in DM and related complications and highlights its potential molecular mechanisms and therapeutic targets. Meanwhile, evidence is provided for the development and application of genistein as a potential drug or functional food in the prevention and treatment of diabetes and its related complications.

Role of flavonoids in controlling obesity: molecular targets and mechanisms

Obesity presents a major health challenge that increases the risk of several non-communicable illnesses, such as but not limited to diabetes, hypertension, cardiovascular diseases, musculoskeletal and neurological disorders, sleep disorders, and cancers. Accounting for nearly 8% of global deaths (4.7 million) in 2017, obesity leads to diminishing quality of life and a higher premature mortality rate among affected individuals. Although essentially dubbed as a modifiable and preventable health concern, prevention, and treatment strategies against obesity, such as calorie intake restriction and increasing calorie burning, have gained little long-term success. In this manuscript, we detail the pathophysiology of obesity as a multifactorial, oxidative stress-dependent inflammatory disease. Current anti-obesity treatment strategies, and the effect of flavonoid-based therapeutic interventions on digestion and absorption, macronutrient metabolism, inflammation and oxidative stress and gut microbiota has been evaluated. The use of several naturally occurring flavonoids to prevent and treat obesity with a long-term efficacy, is also described.

In Vitro Antioxidant and Anti-inflammatory Effects of Erythroxylum cuneatum Leaf Extract on Oxidized Low-density Lipoprotein-stimulated Human Aortic Endothelial Cells

Background

The oxidation of low-density lipoprotein (LDL) by reactive oxygen species (ROS) causes inflammation, which results in the expression of adhesion molecules and monocyte adhesion and migration. This eventually leads to the progression of atherosclerosis. Erythroxylum cuneatum (EC), locally known as “Chinta mula,” is used as traditional medicine in certain countries. However, the scientific evidence of its medicinal properties, particularly related to cardiovascular disease (CVD) is still limited.

Objectives

This study was designed to evaluate the antioxidant and anti-inflammatory properties of EC leaf extract in protecting against atherosclerosis in vitro.

Materials and Methods

Human aortic endothelial cells (HAoECs) induced by oxidized LDL (oxLDL) were treated with comparable concentrations (40 and 80 µg/ml) of EC ethanol and acetone leaf extracts. The antioxidant activities were determined by thiobarbituric acid reactive substances (TBARS), ROS, and nitric oxide (NO) production assays. The anti-inflammatory effects of EC leaf extract were evaluated using monocyte adhesion and migration assays and the expression of adhesion molecules, namely, intracellular adhesion molecule-1 (ICAM-1) and human vascular cell adhesion molecule-1 (VCAM-1).

Results

Both EC extracts possess antioxidant and anti-inflammatory activities against oxLDL-induced HAoECs, which were concentration-dependent. Acetone extract showed significant reduced TBARS levels and increased NO production compared to ethanol extract. It also caused a significant decrease in monocyte adhesion and expression of ICAM-1 as compared to ethanol extract.

Conclusion

These findings suggest that EC leaf extract is valuable in preventing atherogenesis. The superior effect of EC acetone extract warrants future studies to elucidate its mechanisms in the prevention of CVDs, particularly atherosclerosis.

The Potential Role of Connexins in the Pathogenesis of Atherosclerosis

Connexins (Cx) are members of a protein family which enable extracellular and intercellular communication through hemichannels and gap junctions (GJ), respectively. Cx take part in transporting important cell-cell messengers such as 3',5'-cyclic adenosine monophosphate (cAMP), adenosine triphosphate (ATP), and inositol 1,4,5-trisphosphate (IP3), among others. Therefore, they play a significant role in regulating cell homeostasis, proliferation, and differentiation. Alterations in Cx distribution, degradation, and post-translational modifications have been correlated with cancers, as well as cardiovascular and neurological diseases. Depending on the isoform, Cx have been shown either to promote or suppress the development of atherosclerosis, a progressive inflammatory disease affecting large and medium-sized arteries. Cx might contribute to the progression of the disease by enhancing endothelial dysfunction, monocyte recruitment, vascular smooth muscle cell (VSMC) activation, or by inhibiting VSMC autophagy. Inhibition or modulation of the expression of specific isoforms could suppress atherosclerotic plaque formation and diminish pro-inflammatory conditions. A better understanding of the complexity of atherosclerosis pathophysiology linked with Cx could result in developing novel therapeutic strategies. This review aims to present the role of Cx in the pathogenesis of atherosclerosis and discusses whether they can become novel therapeutic targets.

An Overview on Plant Derived Phenolic Compounds and Their Role in Treatment and Management of Diabetes

Objectives

In recent decades, the trend for treating diabetes mellitus (DM) has shifted toward alternative medicines that are obtained from plant sources. Existing literature suggests that phenolic compounds derived from plants possess promising health-promoting properties. This study aimed to discuss the role of plant-derived phenolic compounds in the effective treatment and management of diabetes.

Methods

Information about plant secondary metabolites, phenolic compounds, and their role in the treatment and management of diabetes was collected from different databases, such as Pubmed, ScienceDirect, Scopus, and Google Scholar. Keywords like secondary metabolites, phenolic compounds, simple phenol, flavonoids, lignans, stilbenes, and diabetes were searched. Research and review articles with relevant information were included in the study.

Results

Anti-diabetic studies of the four major classes of phenolic compounds were included in this review. The plant-derived phenolic compounds were reported to have potent anti-diabetic activities. However, each class of phenolic compounds was found to behave differently according to various mechanisms.

Conclusion

The obtained results suggest that phenolic compounds derived from natural sources display promising anti-diabetic activities. Based on the available information, it can be concluded that phenolic compounds obtained from various natural sources play key roles in the treatment and management of diabetes.

Systematic Review of the Impact of Genistein on Diabetes Related Outcomes

Diabetes is the 8th leading cause of death in the world and the prevalence is rising in low-income countries. Cardiovascular diseases are the leading cause of death worldwide, especially for individuals with diabetes. While medications exist to treat symptoms of diabetes, lack of availability and high costs may deter their use by individuals with low incomes as well as those in low-income nations. Therefore, this systematic review was performed to determine whether genistein, a phytoestrogen found in soy products, could provide therapeutic benefits for individuals with diabetes. We searched PubMed and SCOPUS using the terms 'genistein', 'diabetes', and 'glucose' and identified 33 peer-reviewed articles that met our inclusion criteria. In general, preclinical studies demonstrated that genistein decreases body weight and circulating glucose and triglycerides concentrations while increasing insulin levels and insulin sensitivity. Genistein also delayed the onset of type 1 and type 2 diabetes. In contrast, clinical studies utilizing genistein generally reported no significant relationship between genistein and body mass, circulating glucose, A1C concentrations, or onset of type 1 diabetes. However, genistein was found to improve insulin sensitivity and serum triglyceride concentrations and delayed the onset of type 2 diabetes. In summary, preclinical and clinical studies suggest that genistein may help delay the onset of type 2 diabetes and improve several symptoms associated with the disease. Although additional research is required to confirm these findings, the results highlighted in this review provide some evidence that genistein may offer a natural approach to mitigating some of the complications associated with diabetes.

Dietary Blueberry Ameliorates Vascular Complications in Diabetic Mice Possibly through NOX4 and Modulates Composition and Functional Diversity of Gut Microbes

SCOPE

In diabetes, endothelial inflammation and dysfunction play a pivotal role in the development of vascular disease. This study investigates the effect of dietary blueberries on vascular complications and gut microbiome in diabetic mice.

METHODS AND RESULTS

Seven-week-old diabetic db/db mice consume a standard diet (db/db) or a diet supplemented with 3.8% freeze-dried blueberry (db/db+BB) for 10 weeks. Control db/+ mice are fed a standard diet (db/+). Vascular inflammation is assessed by measuring monocyte binding to vasculature and inflammatory markers. Isometric tension procedures are used to assess mesenteric artery function. db/db mice exhibit enhanced vascular inflammation and reduced endothelial-dependent vasorelaxation as compared to db/+ mice, but these are improved in db/db+BB mice. Blueberry supplementation reduces the expression of NOX4 and IκKβ in the aortic vessel and vascular endothelial cells (ECs) isolated from db/db+BB compared to db/db mice. The blueberry metabolites serum reduces glucose and palmitate induced endothelial inflammation in mouse aortic ECs. Further, blueberry supplementation increases commensal microbes and modulates the functional potential of gut microbes in diabetic mice.

CONCLUSION

Dietary blueberry suppresses vascular inflammation, attenuates arterial endothelial dysfunction, and supports the growth of commensal microbes in diabetic mice. The endothelial-specific vascular benefits of blueberries are mediated through NOX4 signaling.

Soy Intake and Risk of Type 2 Diabetes Among Japanese Men and Women: JACC Study

The evidence on the protective effects of soy foods against type 2 diabetes has been inconsistent. We thought to examine the association between the dietary intakes of soy and the risk of diabetes in a prospective study encompassing 21,925 healthy Japanese men and women aged 40–79 years. A validated self-administered food frequency questionnaire determined the intakes of soy, and their associations with risk of type 2 diabetes were evaluated by the logistic regression analysis. During the 5-year follow-up period, we observed 593 new cases of type 2 diabetes (302 in men and 291 in women). There was no association between dietary intakes of soy foods and the risk of type 2 diabetes among men. Whereas among women, higher tofu intake was inversely associated with risk of type 2 diabetes; the multivariable odds ratios (ORs) of type 2 diabetes were 0.92 (95% CI: 0.69–1.21) for 3–4 times per week and 0.67 (95% CI: 0.49–0.94) for almost daily (p-trend = 0.03) in reference to those consuming tofu less than 3 times per week. Intakes of boiled beans and miso soup were not associated with the risk in both genders. The inverse association tended to be more evident among overweight women and postmenopaused women. In conclusion, the frequency of tofu intake was inversely associated with the risk of type 2 diabetes among women.

Genistein: A Review on its Anti-Inflammatory Properties

Nowadays, non-resolving inflammation is becoming a major trigger in various diseases as it plays a significant role in the pathogenesis of atherosclerosis, asthma, cancer, obesity, inflammatory bowel disease, chronic obstructive pulmonary disease, neurodegenerative disease, multiple sclerosis, and rheumatoid arthritis. However, prolonged use of anti-inflammatory drugs is usually accompanied with undesirable effects and hence more patients tend to seek for natural compounds as alternative medicine. Considering the fact above, there is an urgency to discover and develop potential novel, safe and efficacious natural compounds as drug candidates for future anti-inflammatory therapy. Genistein belongs to the flavonoid family, in the subgroup of isoflavones. It is a phytoestrogen that is mainly derived from legumes. It is a naturally occurring chemical constituent with a similar chemical structure to mammalian estrogens. It is claimed to exert many beneficial effects on health, such as protection against osteoporosis, reduction in the risk of cardiovascular disease, alleviation of postmenopausal symptoms and anticancer properties. In the past, numerous in vitro and in vivo studies have been conducted to investigate the anti-inflammatory potential of genistein. Henceforth, this review aims to summarize the anti-inflammatory properties of genistein linking with the signaling pathways and mediators that are involved in the inflammatory response as well as its toxicity profile. The current outcomes are analysed to highlight the prospect as a lead compound for drug discovery. Data was collected using PubMed, ScienceDirect, SpringerLink and Scopus databases. Results showed that genistein possessed strong anti-inflammatory activities through inhibition of various signaling pathways such as nuclear factor kappa-B (NF-κB), prostaglandins (PGs), inducible nitric oxide synthase (iNOS), proinflammatory cytokines and reactive oxygen species (ROS). A comprehensive assessment of the mechanism of action in anti-inflammatory effects of genistein is included. However, evidence for the pharmacological effects is still lacking. Further studies using various animal models to assess pharmacological effects such as toxicity, pharmacokinetics, pharmacodynamics, and bioavailability studies are required before clinical studies can be conducted. This review will highlight the potential use of genistein as a lead compound for future drug development as an anti-inflammatory agent.

Activated monocytes as a therapeutic target to attenuate vascular inflammation and lower cardiovascular disease-risk in patients with type 2 diabetes: A systematic review of preclinical and clinical studies

Low grade inflammation is associated with the progression of atherosclerosis. Patients with type 2 diabetes (T2D) have altered cholesterol levels, which are targeted by free radicals to promote lipid peroxidation. Elevated levels of monocyte-associated cytokines such as interleukin (IL)-6, monocyte chemoattractant protein 1 (MCP-1), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), and tumor necrosis factor-alpha (TNF-α), subsequently drive endothelial tissue injury. In fact, the levels of circulating platelet-monocyte aggregates in patients with T2D is a robust marker for atherosclerosis and a cardiovascular disease (CVD)-risk factor. To identify eligible studies, we searched the major online databases using PubMed and Google Scholar. The cumulative evidence synthesized in the current review suggests that, traditional therapies which include thiazolidinediones, statins and some calcium channel blockers can be useful in the primary prevention of atherosclerosis by inhibiting the formation of monocyte-derived microparticles, and pro-inflammatory cytokines such as IL-6, TNF-α, MCP-1, and NF-κB in patients with T2D. Future studies are needed to ascertain whether the combination of dietary interventions and glucose or lipid lowering agents can provide an enhanced cardioprotection in patients with T2D.

Polyphenols: Potential anti-inflammatory agents for treatment of metabolic disorders

Ample evidence highlights the potential benefits of polyphenols in health status especially in obesity-related metabolic disorders such as insulin resistance, type 2 diabetes, and cardiovascular diseases. Mechanistically, due to the key role of "Metainflammation" in the pathomechanism of metabolic disorders, recently much focus has been placed on the properties of polyphenols in obesity-related morbidities. This narrative review summarizes the current knowledge on the role of polyphenols, including genistein, chlorogenic acid, ellagic acid, caffeic acid, and silymarin in inflammatory responses pertinent to metabolic disorders and discusses the implications of this evidence for future directions. This review provides evidence that the aforementioned polyphenols benefit health status in metabolic disorders via direct and indirect regulation of a variety of target proteins involved in inflammatory signaling pathways. However, due to limitations of the in vitro and in vivo studies and also the lack of long-term human clinical trials studies, further high-quality investigations are required to firmly establish the clinical efficacy of the polyphenols for the prevention and management of metabolic disorders.

Revealing the Angiopathy of Lacrimal Gland Lesion in Type 2 Diabetes

For a better understanding of diabetic angiopathy (DA), the potential biomarkers in lacrimal DA and its potential mechanism, we evaluated the morphological and hemodynamic alterations of lacrimal glands (LGs) in patients with type 2 diabetes and healthy counterparts by color Doppler flow imaging (CDFI). We further established a type 2 diabetic mice model and performed hematoxylin-eosin (HE) staining, immunofluorescence staining of CD31, RNA-sequencing analysis, and connectivity map (CMap) analysis. We found atrophy and ischemia in patients with type 2 diabetes and mice models. Furthermore, we identified 846 differentially expressed genes (DEGs) between type 2 diabetes mellitus (T2DM) and vehicle mice by RNA-seq. The gene ontology (GO) analysis indicated significant enrichment of immune system process, regulation of blood circulation, apoptotic, regulation of secretion, regulation of blood vessel diameter, and so on. The molecular complex detection (MCODE) showed 17 genes were involved in the most significant module, and 6/17 genes were involved in vascular disorders. CytoHubba revealed the top 10 hub genes of DEGs, and four hub genes (App, F5, Fgg, and Gas6) related to vascular regulation were identified repeatedly by MCODE and cytoHubba. GeneMANIA analysis demonstrated functions of the four hub genes above and their associated molecules were primarily related to the regulation of circulation and coagulation. CMap analysis found several small molecular compounds to reverse the altered DEGs, including disulfiram, bumetanide, genistein, and so on. Our outputs could empower the novel potential targets to treat lacrimal angiopathy, diabetes dry eye, and other diabetes-related diseases.

Mormodica charantia L. fruit and Genistein ameliorates type 2 diabetes in rats by preventing lipid accumulation, insulin resistance and enhancing beta cell function

PURPOSE

The present study was aimed at evaluating the role of Momordica charantia L. fruit and Genistein on beta cell, insulin resistance/sensitivity and lipid profile in type 2 diabetic rats.

METHODS

Thirty-five (35) albino rats were divided into seven (7) groups of 5 rats each comprising of five (5) non-diabetic and thirty (30) diabetic rats. Groups 1 and 2 served as the normal control and diabetic control groups respectively and received distill water, groups 3 and 4 received Mormodica charantia L. at 250 mg/kg and 500 mg/kg respectively. Groups 5 and 6 received Genistein at 10 mg/kg and 20 mg/kg respectively while group 7 received Metformin at 500 mg/kg the experiment lasted for four weeks. All the rats were euthanized at the end of the fourth week.

RESULTS

Lipid profile, glucose and insulin levels were determined from the analysis of serum parameters and the histology of the pancreas. A significant reduction (p < 0.05) in blood glucose levels was noticed in rats that received Momordica charantia L. (MC) and genistein when compared with diabetic control rats. A significant decrease (p < 0.05) in cholesterol, triglyceride, low density lipoprotein (LDL) and very low density lipoprotein (VLDL) levels were also noted in rats that received MC and Genistein when compared with the diabetic control rats. MC and Genistein significantly increased (P < 0.05) serum insulin level compared to the diabetic control rats. MC and Genistein significantly decreased (p < 0.05) homeostatic model assessment-insulin resistance (HOMA-IR) level compared with the diabetic control group. Pancreas of rats that received MC and Genistein showed regenerating beta-cells.

CONCLUSION

Momordica charantia L. fruit and Genistein were able to enhance beta cell function and prevent lipid accumulation and insulin resistance in type 2 diabetic rats.

Evaluation of the possibility of selective modulation of retinal glucose transporters in diabetic complications: An experimental study

PURPOSE:

To identify the possibility of modulating retinal glucose transporters in diabetic conditions to prevent retinal complications of diabetic retinopathy.

MATERIALS AND METHODS:

In silico and in vitro binding assays were performed to assess the effect of genistein and positive controls (pioglitazone and estradiol) on nuclear receptor estrogen receptor beta and peroxisome proliferator-activated receptor gamma (PPARγ). In vivo effects of compounds were tested on diabetic rats. Structural and functional analysis of retina was performed at 28^th day followed by gene expression analysis of glucose transporters and nuclear receptors. Pioglitazone and genistein levels were analyzed by liquid chromatography with tandem mass spectrometry.

RESULTS:

Genistein showed equi-affinity toward PPARγ in In silico experiments contrary to in vitro findings. In multidose study, their therapeutic effects were observed by analyzing the retinal function. Retinal gene expression studies revealed that both test agents significantly up regulated PPARγ, GLUT4, and down regulated GLUT1. Genistein showed significant up regulation of GLUT4 and down regulation of GLUT1 as compared to PGZ which has been well correlated with the Electroretinography (ERG) outcome.

CONCLUSION:

This study showed the possibility of selective upregulation of GLUT4 (independent of PPARγ activation) in the retina of diabetic rats using genistein. Selective modulation of retinal glucose transporters as therapeutic target in ocular diabetic complications can be possibly explored.

Soy Isoflavones Inhibit Endothelial Cell Dysfunction and Prevent Cardiovascular Disease

Soybeans are among the most popular foods worldwide, and intake of soy-containing foods has been associated with many health benefits in part because of it structure similar to estrogen. Epidemiologic studies have demonstrated that soy consumption improves serum profiles of hypercholesterolemic patients. Several studies have also indicated an inverse relationship between the consumption of soy isoflavones and the incidence of cardiovascular diseases (CVD). Soy is a rich dietary source of isoflavones. The main soy isoflavones are daidzein and genistein; equol, another isoflavone and a major intestinal bacterial metabolite of daidzein, is generated by enterobacterial effects. Many isoflavones have antioxidative effects and anti-inflammatory actions, as well as induce nitric oxide production to maintain a healthy endothelium and prevent endothelial cell dysfunction. These effects may limit the development of atherosclerosis and CVD and restore healthy endothelial function in altered endothelia. Although the evidence supporting the benefits of soy isoflavones in CVD prevention continues to increase, the association between soy isoflavones and disease is not fully understood. This review summarized recent progress in identifying the preventive mechanisms of action of dietary soybean isoflavones on vascular endothelial cells. Furthermore, it describes the beneficial roles that these isoflavones may have on endothelial dysfunction-related atherosclerosis.

Phenolic Compounds Exerting Lipid-Regulatory, Anti-Inflammatory and Epigenetic Effects as Complementary Treatments in Cardiovascular Diseases

Atherosclerosis is the main process behind cardiovascular diseases (CVD), maladies which continue to be responsible for up to 70% of death worldwide. Despite the ongoing development of new and potent drugs, their incomplete efficacy, partial intolerance and numerous side effects make the search for new alternatives worthwhile. The focus of the scientific world turned to the potential of natural active compounds to prevent and treat CVD. Essential for effective prevention or treatment based on phytochemicals is to know their mechanisms of action according to their bioavailability and dosage. The present review is focused on the latest data about phenolic compounds and aims to collect and correlate the reliable existing knowledge concerning their molecular mechanisms of action to counteract important risk factors that contribute to the initiation and development of atherosclerosis: dyslipidemia, and oxidative and inflammatory-stress. The selection of phenolic compounds was made to prove their multiple benefic effects and endorse them as CVD remedies, complementary to allopathic drugs. The review also highlights some aspects that still need clear scientific explanations and draws up some new molecular approaches to validate phenolic compounds for CVD complementary therapy in the near future.

Flavonoids and type 2 diabetes: Evidence of efficacy in clinical and animal studies and delivery strategies to enhance their therapeutic efficacy

Diabetes mellitus type 2 (T2DM) is a metabolic disorder develops due to the overproduction of free radicals where oxidative stress could contribute it. Possible factors are defective insulin signals, glucose oxidation, and degradation of glycated proteins as well as alteration in glutathione metabolism which induced hyperglycemia. Previous studies revealed a link between T2DM with oxidative stress, inflammation and insulin resistance which are assumed to be regulated by numerous cellular networks such as NF-κB, PI3K/Akt, MAPK, GSK3 and PPARγ. Flavonoids are ubiquitously present in the nature and classified according to their chemical structures for example, flavonols, flavones, flavan-3-ols, anthocyanidins, flavanones, and isoflavones. Flavonoids indicate poor bioavailability which could be improved by employing various nano-delivery systems against the occurrences of T2DM. These bioactive compounds exert versatile anti-diabetic activities via modulating targeted cellular signaling networks, thereby, improving glucose metabolism, α -glycosidase, and glucose transport or aldose reductase by carbohydrate metabolic pathway in pancreatic β-cells, hepatocytes, adipocytes and skeletal myofibres. Moreover, anti-diabetic properties of flavonoids also encounter diabetic related complications. This review article has designed to shed light on the anti-diabetic potential of flavonoids, contribution of oxidative stress, evidence of efficacy in clinical, cellular and animal studies and nano-delivery approaches to enhance their therapeutic efficacy. This article might give some new insights for therapeutic intervention against T2DM in near future.

Dietary plant flavonoids in prevention of obesity and diabetes

Obesity and diabetes are the most prevailing chronic metabolic diseases worldwide from mainly lipid and glucose metabolic dysfunctions and their incidence is increasing at an alarming high rate. Obesity is characterized by excess fat accumulation in WAT and liver and is the central player of insulin resistance in the peripheral tissues from chronic inflammation, lipotoxicity and gut dysbiosis, and plays a key role for development of type 2 diabetes (T2DM) and vascular diseases. Diabetes mellitus, known as diabetes, is chiefly characterized by hyperglycaemia from impaired insulin secretion and insulin resistance. Several identified mutant genes in insulin secretion and resistance and various environmental factors are considered responsible for the onset of this disease. Currently available oral synthetic drugs, biguanides, incretin mimetic, GLP-1R and PPAR agonists and DPP-4 inhibitors for management of obesity and diabetes have several adverse effects in patients on long-term use. Emerging evidence supports the efficacy of dietary plant flavonoids in prevention and attenuation of obesity and diabetes by the protection and proliferation of pancreatic beta-cells and improvement of their insulin secretory function via activation of cAMP/PKA signaling pathway as well as in the improvement of insulin sensitivity in the peripheral metabolic tisssues for glucose uptake and utilization via inhibition of inflammation, lipotoxicity and oxidative stress. These flavonoids improve GLUT-4 expression and translocation to plasma membrane by activation of insulin-sensitive PI3K/Akt signaling and insulin-independent AMPK, SIRT-1 and MOR activation pathways for regulation of glucose homeostasis, and improve fat oxidation and reduce lipid synthesis by regulation of related genes for lipid homeostasis in the body of obese diabetic animals. In this chapter, we have highlighted all these beneficial anti-obesity and antidiabetic potentials of some dietary plant flavonoids along with their molecular actions, bioavailability and pharmacokinetics. In addition, the present understanding and management of obesity and diabetes are also focused.

Flavonoids and Their Anti-Diabetic Effects: Cellular Mechanisms and Effects to Improve Blood Sugar Levels

Diabetes mellitus (DM) is a prevailing global health metabolic disorder, with an alarming incidence rate and a huge burden on health care providers. DM is characterized by the elevation of blood glucose due either to a defect in insulin synthesis, secretion, binding to receptor, or an increase of insulin resistance. The internal and external factors such as obesity, urbanizations, and genetic mutations could increase the risk of developing DM. Flavonoids are phenolic compounds existing as secondary metabolites in fruits and vegetables as well as fungi. Their structure consists of 15 carbon skeletons and two aromatic rings (A and B) connected by three carbon chains. Flavonoids are furtherly classified into 6 subclasses: flavonols, flavones, flavanones, isoflavones, flavanols, and anthocyanidins. Naturally occurring flavonoids possess anti-diabetic effects. As in vitro and animal model's studies demonstrate, they have the ability to prevent diabetes and its complications. The aim of this review is to summarize the current knowledge addressing the antidiabetic effects of dietary flavonoids and their underlying molecular mechanisms on selected pathways: Glucose transporter, hepatic enzymes, tyrosine kinase inhibitor, AMPK, PPAR, and NF-κB. Flavonoids improve the pathogenesis of diabetes and its complications through the regulation of glucose metabolism, hepatic enzymes activities, and a lipid profile. Most studies illustrate a positive role of specific dietary flavonoids on diabetes, but the mechanisms of action and the side effects need more clarification. Overall, more research is needed to provide a better understanding of the mechanisms of diabetes treatment using flavonoids.

Genistein protects against DSS-induced colitis by inhibiting NLRP3 inflammasome via TGR5-cAMP signaling

NLRP3 inflammasome has been reported to be associated with inflammatory bowel disease including colitis due to its potential ability to induce IL-1β secretion. Emerging studies have demonstrated that Genistein, a major isoflavone, has potential anti-inflammatory effects in murine model colitis. However, its anti-inflammatory mechanism remains unclear. The effects of Genistein in dextran sulfate sodium (DSS)-induced murine colitis via targeting NLRP3 inflammasome was investigated in this study. Also, the mechanisms of protective action of Genistein in DSS-induced colitis may relate to TGR5 signaling. Genistein treatment not only remarkably attenuated loss of body weight and shortening of colon length but also significantly reduced inflammatory cells infiltration and pro-inflammatory mediator production in serum and colon. Moreover, Genistein treatment down-regulated production of caspase-1 and IL-1β and increased intracellular cAMP level, which were similar to the treatment for INT-777, a semi-synthetic TGR5 agonist, in phorbol myristate acetate (PMA)-differentiated monocytic THP-1 cells and U937 cells. These protective effects of Genistein might be attributed by ubiquination of NLRP3 which was induced due to interaction of cAMP with NLRP3. Furthermore, the effects of Genistein on NLRP3 inflammasome disappeared in TGR5-silenced U937 cells. In conclusion, our study unveils that Genistein was able to inhibit NLRP3 inflammasome via TGR5-cAMP signaling in macrophages. It therefore might be a potential effective drug for inflammatory bowel diseases.

Effects of three flavonoids from an ancient traditional Chinese medicine Radix puerariae on geriatric diseases

As the worldwide population ages, the morbidity of neurodegenerative, cardiovascular, cerebrovascular, and endocrine diseases, such as diabetes and osteoporosis, continues to increase. The etiology of geriatric diseases is complex, involving the interaction of genes and the environment, which makes effective treatment challenging. Traditional Chinese medicine, unlike Western medicine, uses diverse bioactive ingredients to target multiple signaling pathways in geriatric diseases. Radix puerariae is one of the most widely used ancient traditional Chinese medicines and is also consumed as food. This review summarizes the evidence from in vivo and in vitro studies of the pharmacological effects of the main active components of the tuber of Radix puerariae on geriatric diseases.

Soy genistein administered in soluble chitosan microcapsules maintains antioxidant activity and limits intestinal inflammation

We used water-soluble Chitosan obtained by Maillard reaction with glucosamine to microencapsulate soy genistein (Ge) and preserve its biological activity for oral administration. Release of Ge was pH dependent with a super Case II mechanism at pH 1.2 and an anomalous transport with non-Fickian kinetics at pH 6.8. Microencapsulated Ge retained its antioxidant properties in vitro and its daily administration to mice attenuated clinical signs of acute colitis, limited inflammatory reaction and reduced oxidative stress and tissue injury as well. Remarkably, after feeding microencapsulated Ge the production of IL-10 in colonic tissue was restored to levels of untreated controls. According to statistical multivariate analysis, this cytokine was the parameter with the highest influence on the inflammatory/oxidative status. Microencapsulation of Ge with derivatized Chitosan becomes an interesting alternative to develop therapeutic approaches for oxidative inflammatory diseases; our findings suggest that the soy isoflavone could be incorporated into any functional food for application in intestinal inflammation.

Curcumin attenuates high glucose-induced inflammatory injury through the reactive oxygen species-phosphoinositide 3-kinase/protein kinase B-nuclear factor-κB signaling pathway in rat thoracic aorta endothelial cells

AIMS/INTRODUCTION

Endothelial cell inflammatory injury is likely required for barrier dysfunction under hyperglycemic conditions. Curcumin (CUR) is well known for its anti-inflammatory effect. However, there have been few reports about the anti-inflammatory effect of CUR induced by high glucose in endothelial cells. The aim of the present study was to investigate the inflammatory effect of high glucose and the anti-inflammatory effect of CUR induced by high glucose in rat thoracic aorta endothelial cells (TAECs).

MATERIALS AND METHODS

Well characterized TAECs were established and cell viability was assayed by the cell counting kit-8 method, messenger ribonucleic acid and protein expression were identified by real-time polymerase chain reaction, western blot or enzyme-linked immunosorbent assay, respectively. The production of reactive oxygen species was observed by a fluorescence microscope.

RESULTS

High glucose (30 mmol/L) significantly decreased the cell viability of TAECs after being co-cultivated for 12 h and showed a time-dependent manner, and increased interleukin (IL)-1β, IL-6 and tumor necrosis factor-α secretion in TAECs. The injury effect of high glucose was involved in the reactive oxygen species-phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)-nuclear factor (NF)-κB signaling pathway. Anti-oxidant N-acetylcysteine, PI3K and NF-κB-specific pathway inhibitors can abolish the secretion of these inflammatory factors; pretreatment with anti-oxidant N-acetylcysteine significantly decreased PI3K expression, the level of phosphorylated AKT and nuclear NF-κB; pretreatment of LY294002 can significantly decrease the NF-κB level in nuclei. After treatment with CUR for 12 h, IL-1β, IL-6 and tumor necrosis factor-α secretion were markedly decreased, and PI3K expression, the phosphorylation of AKT and nuclear NF-κB level were also decreased.

CONCLUSION

Curcumin attenuates high glucose-induced inflammatory injury through the reactive oxygen species-PI3K/AKT-NF-κB signaling pathway in rat thoracic aorta endothelial cells.

Dietary flavonoids as a potential intervention to improve redox balance in obesity and related co-morbidities: a review

Obesity represents one of major health problems strongly linked to other co-morbidities, such as type 2 diabetes, CVD, gastrointestinal disorders and cognitive impairment. In this context, nutritional stress, such as an excess of fat intake, promotes a systemic oxidative stress, characterised by hyperproduction of reactive oxygen species, leading to cellular alterations that include impaired energy metabolism, altered cell signalling and cell cycle control, impaired cell transport mechanisms and overall dysfunctional biological activity. Flavonoids, dietary components of plant foods, are endowed with a wide spectrum of biological activities, including antioxidant activity, and have been proposed to reduce the risk of major chronic diseases. The present review intends to highlight and critically discuss the current scientific evidence on the possible effects of flavonoids in counteracting obesity and related co-morbidities (i.e. type 2 diabetes mellitus, CVD, gastrointestinal disorders and cognitive impairment) through a decrease in oxidative stress and related inflammatory conditions.

Circulating metabolites of strawberry mediate reductions in vascular inflammation and endothelial dysfunction in db/db mice

BACKGROUND

Cardiovascular disease is 2-4-fold more prevalent in patients with diabetes. Human studies support the cardiovascular benefits of strawberry consumption but the effects of strawberry on diabetic vasculature are unknown. We tested the hypothesis that dietary strawberry supplementation attenuates vascular inflammation and dysfunction in diabetic mice.

METHODS

Seven-week-old diabetic db/db mice that consumed standard diet (db/db) or diet supplemented with 2.35% freeze-dried strawberry (db/db + SB) for ten weeks were compared to non-diabetic control mice (db/+). Indices of vascular inflammation and dysfunction were measured. Endothelial cells (ECs) were isolated from the vasculature to determine the influence of strawberry on them. The effect of metabolites of strawberry on endothelial inflammation was determined by incubating mouse aortic ECs (MAECs) with ±5% serum, obtained from strawberry fed mice (metabolites serum) or standard diet fed mice (control serum) ± 25 mM glucose and 100 μM palmitate.

RESULTS

db/db mice exhibited an increased monocyte binding to vessel, elevated blood pressure, and reduced endothelial-dependent vasorelaxation compared with db/+ mice but each defect was attenuated in db/db + SB mice. The elevation of inflammatory molecules, NOX2 and inhibitor-κB kinase observed in ECs from db/db vs. db/+ mice was suppressed in db/db + SB mice. Glucose and palmitate increased endothelial inflammation in MAECs but were normalized by co-incubation with metabolites serum.

CONCLUSIONS

Dietary supplementation of strawberry attenuates indices of vascular inflammation and dysfunction in diabetic db/db mice. The effect of strawberry on vasculature is endothelial-dependent and possibly mediated through their circulating metabolites. Strawberry might complement conventional therapies to improve vascular complications in diabetics.

Blueberry metabolites restore cell surface glycosaminoglycans and attenuate endothelial inflammation in diabetic human aortic endothelial cells

BACKGROUND

Glycosaminoglycan (GAG), a major component of the endothelial glycocalyx, is severely perturbed in diabetic vasculature leading to endothelial inflammation and vascular disease in diabetes. We tested the hypothesis that blueberry metabolites (BBM) ameliorate endothelial inflammation in diabetic endothelial cells (ECs) by restoring cell surface GAGs.

METHODS

ECs isolated from healthy individuals [human aortic ECs (HAECs)] and diabetic patients (diabetic HAECs) were treated with ±BBM (benzoic acid-4-sulfate, hippuric acid, hydroxyhippuric acid, isovanillic acid-3-sulfate, and vanillic acid-4-sulfate at concentrations known to circulate in human plasma following blueberry consumption) for 3 days, and indices for endothelial inflammation were measured. To analyze GAGs, ECs were incubated with sulfate-free medium supplemented with [₃₅S] Na₂SO₄ ± BBM. Total GAGs in ECs and medium were purified using DEAE-Sepharose column and were analyzed with high-pressure liquid chromatography coupled to an inline flow scintillation analyzer. Heparan sulfate/chondroitin sulfate ratio and disaccharide composition of GAGs from the medium were analyzed using DEAE-3SW column and Dionex CarboPac PA1 column, respectively.

RESULTS

BBM suppressed diabetes-induced monocyte binding to ECs, and reduced the expression of inflammatory markers in diabetic HAECs. Diabetic HAECs displayed a decrease in [³⁵S] sulfate incorporation into the cell surface GAGs indicating the dysregulation of sulfated GAGs. However, treatment with BBM restored the levels of GAGs in diabetic HAECs. The composition, heparan sulfate/chondroitin sulfate ratio, and disaccharide composition of GAGs from medium were similar among groups.

CONCLUSIONS

BBM restored cell surface GAGs and attenuated endothelial inflammation in diabetic HAECs. Blueberry might complement conventional therapies to improve vascular complications in diabetes.

Blueberry Metabolites Attenuate Lipotoxicity-Induced Endothelial Dysfunction

SCOPE

Lipotoxicity-induced endothelial dysfunction is an important vascular complication associated with diabetes. Clinical studies support the vascular benefits of blueberry anthocyanins, but the underlying mechanism is unclear. The hypothesis that metabolites of blueberry anthocyanins attenuate lipotoxicity-induced endothelial dysfunction was tested.

METHODS AND RESULTS

Human aortic endothelial cells (HAECs) were treated for 6 h with either: (i) the parent anthocyanins (malvidin-3-glucoside and cyanidin-3-glucoside); or (ii) the blueberry metabolites (hydroxyhippuric acid, hippuric acid, benzoic acid-4-sulfate, isovanillic acid-3-sulfate, and vanillic acid-4-sulfate), at concentrations known to circulate in humans following blueberry consumption. For the last 5 h HAECs were treated with palmitate or vehicle. HAECs treated with palmitate displayed elevated reactive oxygen species generation, increased mRNA expression of NOX4, chemokines, adhesion molecules, and IκBα, exaggerated monocyte binding, and suppressed nitric oxide production. Of note, the damaging effects of palmitate were ameliorated in HAECs treated with blueberry metabolites but not parent anthocyanins. Further, important translational relevance of these results was provided by our observation that palmitate-induced endothelial dysfunction was lessened in arterial segments that incubated concurrently with blueberry metabolites.

CONCLUSION

The presented findings indicate that the vascular benefits of blueberry anthocyanins are mediated by their metabolites. Blueberries might complement existing therapies to lessen vascular complications.

Human monocyte-derived dendritic cells exposed to hyperthermia show a distinct gene expression profile and selective upregulation of IGFBP6

Fever plays a role in activating innate immunity while its relevance in activating adaptive immunity is less clear. Even brief exposure to elevated temperatures significantly impacts on the immunostimulatory capacity of dendritic cells (DCs), but the consequences on immune response remain unclear. To address this issue, we analyzed the gene expression profiles of normal human monocyte-derived DCs from nine healthy adults subjected either to fever-like thermal conditions (39°C) or to normal temperature (37°C) for 180 minutes. Exposure of DCs to 39°C caused upregulation of 43 genes and downregulation of 24 genes. Functionally, the up/downregulated genes are involved in post-translational modification, protein folding, cell death and survival, and cellular movement. Notably, when compared to monocytes, DCs differentially upregulated transcription of the secreted protein IGFBP-6, not previously known to be specifically linked to hyperthermia. Exposure of DCs to 39°C induced apoptosis/necrosis and resulted in accumulation of IGFBP-6 in the conditioned medium at 48 h. IGFBP-6 may have a functional role in the hyperthermic response as it induced chemotaxis of monocytes and T lymphocytes, but not of B lymphocytes. Thus, temperature regulates complex biological DC functions that most likely contribute to their ability to induce an efficient adaptive immune response.

Mechanistic insights into the vascular effects of blueberries: Evidence from recent studies

Cardiovascular disease is the leading cause of death in the United States. Dietary habits influence a variety of cardiovascular complications such as peripheral artery disease, heart failure, and kidney disease. We along with others have previously reported the cardiovascular beneficial effects of dietary flavonoids. Anthocyanins, one class of flavonoids widely available in berries, have recently drawn wide scientific attention because of their diverse health benefits. Epidemiological, clinical, and animal studies indicate that blueberry anthocyanins exert protection against cardiovascular complications by acting on multiple targets in the vascular system. These include activating endothelial nitric oxide synthase signaling, reducing oxidative stress, improving inflammatory pathways, and ameliorating dyslipidemia. Anthocyanins are extensively metabolized in humans suggesting that their vascular benefits are likely mediated by their circulating metabolites. However, the bioactivities of blueberry metabolites are unknown. Evaluating the bioactivities of metabolites, analyzing their structure-activity relationship, and well-designed human trials are needed to understand the potential vascular effects of blueberries and their metabolites. Understanding the vascular effects will provide a solid scientific foundation to recommend blueberries to improve vascular health. This review highlights the recent developments in the understanding of the vascular effects of blueberries with special emphasis on the molecular mechanisms involved.

γ-Carboxyethyl hydroxychroman, a metabolite of γ-tocopherol, preserves nitric oxide bioavailability in endothelial cells challenged with high glucose

Endothelial dysfunction occurs when there are imbalances between factors that regulate the synthesis and degradation of nitric oxide (NO^•), and has been reported in patients with hyperglycemia and insulin resistance. We reported that supplementation with γ-tocopherol (γ-T) in humans limits impairments in endothelial function otherwise induced by postprandial hyperglycemia. Given the rapid metabolism of γ-T into γ-carboxyethyl hydroxychroman (γ-CEHC), we hypothesized that the vasoprotective activities of γ-T could be attributed to its metabolite γ-CEHC. To test this, human aortic endothelial cells (HAECs) treated with 0 (vehicle control) or 3 µM γ-CEHC for 24 h prior to incubation with normal (5 mM) or high (25 mM) glucose for 48 h. High-glucose increased levels of uncoupled endothelial nitric oxide synthase (eNOS) as evidenced by reduced ( p < 0.05) eNOS dimer:monomer. High glucose also prevented insulin-stimulated increases in p-Akt^Ser473: total Akt, p-eNOS^Ser1177: total eNOS, and NO^• production. These adverse changes were accompanied by increased ( p < 0.05) reactive oxygen species and mRNA expression of inflammatory mediators (VCAM-1, E-selectin, IL-8). However, each deleterious response evoked by high glucose was prevented when HAECs were incubated with γ-CEHC prior to the high glucose challenge. Taken together, our data support the hypothesis that vascular protection provided by γ-T in vivo may be elicited through the bioactivity of its metabolite, γ-CEHC. Furthermore, it is possible that the antioxidant and anti-inflammatory activities of γ-CEHC may mediate this protective activity.

Not lost in translation: Emerging clinical importance of the G protein-coupled estrogen receptor GPER

It has been 20years that the G protein-coupled estrogen receptor (GPER) was cloned as the orphan receptor GPR30 from multiple cellular sources, including vascular endothelial cells. Here, I will provide an overview of estrogen biology and the historical background leading to the discovery of rapid vascular estrogen signaling. I will also review the recent advances in the understanding of the mechanisms underlying GPER function, its role in physiology and disease, some of the currently available GPER-targeting drugs approved for clinical use such as SERMs (selective estrogen receptor modulators) and SERDs (selective estrogen receptor downregulators). Many of currently used drugs such as tamoxifen, raloxifene, or faslodex™/fulvestrant were discovered targeting GPER many years after they had been introduced to the clinics for entirely different purposes. This has important implications for the clinical use of these drugs and their modes of action, which I have termed 'reverse translational medicine'. In addition, environmental pollutants known as 'endocrine disruptors' have been found to bind to GPER. This article also discusses recent evidence in these areas as well as opportunities in translational clinical medicine and GPER research, including medical genetics, personalized medicine, prevention, and its theranostic use.

The effects of genistein supplementation on fructose induced insulin resistance, oxidative stress and inflammation

AIMS

This experimental study was designed to investigate the effects of 10weeks genistein administration on oxidative stress and inflammation in serum and liver of rats fed with fructose.

MAIN METHODS

6-8weeks old, 40 male Sprague-Dawley rats were included. Group 1 (control) was fed with standard chow food and 100μl/kg/day/rat dimethyl sulfoxide (DMSO) administered subcutaneously; group 2 (genistein) with standard chow food and 0.25mg/kg/day/rat genistein; group 3 (fructose) with standard chow food and drinking water 20% fructose, group 4 (fructose+genistein) with standard chow food, drinking water with 20% fructose and 0.25mg/kg/day/rat genistein. TNF-α, IL-6, visfatin as inflammatory markers and 8-isoprostane as a oxidative stress marker were measured by ELISA, glucose, triglyceride, total cholesterol, LDL-cholesterol and HDL-cholesterol by enzymatic colorimetric method, AST and ALT by kinetic UV method.

KEY FINDINGS

Significantly high 8-isoprostane levels in serum (p<0.001) and liver (p<0.05) in group 3 compared to control group indicate that presence of oxidative stress. Significantly high TNF-α and IL-6 levels in serum (p<0.05) and liver (p<0.01) and visfatin levels in serum (p<0.001) of group 3 indicate inflammation accompanying insulin resistance and oxidative stress. Genistein administration to fructose group causes a significant decrease in HOMA-IR (p<0.001) and LDLC (p<0.05) level. Significantly lower serum 8-isoprostane (p<0.01) level indicates the antioxidant effect of genistein and significantly lower liver TNF-α (p<0.01), serum, liver IL-6(p<0.01) and serum visfatin (p<0.01) levels reflect the antiinflammatory effects of genistein.

SIGNIFICANCE

Genistein administration to rats fed with fructose causes an ameliorating effect on HOMA-IR values and lipid status markers in addition to its antioxidant and antiinflammatory effects.

Reversibility of endothelial dysfunction in diabetes: role of polyphenols

The endothelium, a thin single sheet of endothelial cells, is a metabolically active layer that coats the inner surface of blood vessels and acts as an interface between the circulating blood and the vessel wall. The endothelium through the secretion of vasodilators and vasoconstrictors serves as a critical mediator of vascular homeostasis. During the development of the vascular system, it regulates cellular adhesion and vessel wall inflammation in addition to maintaining vasculogenesis and angiogenesis. A shift in the functions of the endothelium towards vasoconstriction, proinflammatory and prothrombic states characterise improper functioning of these cells, leading to endothelial dysfunction (ED), implicated in the pathogenesis of many diseases including diabetes. Major mechanisms of ED include the down-regulation of endothelial nitric oxide synthase levels, differential expression of vascular endothelial growth factor, endoplasmic reticulum stress, inflammatory pathways and oxidative stress. ED tends to be the initial event in macrovascular complications such as coronary artery disease, peripheral arterial disease, stroke and microvascular complications such as nephropathy, neuropathy and retinopathy. Numerous strategies have been developed to protect endothelial cells against various stimuli, of which the role of polyphenolic compounds in modulating the differentially regulated pathways and thus maintaining vascular homeostasis has been proven to be beneficial. This review addresses the factors stimulating ED in diabetes and the molecular mechanisms of natural polyphenol antioxidants in maintaining vascular homeostasis.

Molecular Mechanisms of the Anti-Obesity and Anti-Diabetic Properties of Flavonoids

Obesity and diabetes are the most prevailing health concerns worldwide and their incidence is increasing at a high rate, resulting in enormous social costs. Obesity is a complex disease commonly accompanied by insulin resistance and increases in oxidative stress and inflammatory marker expression, leading to augmented fat mass in the body. Diabetes mellitus (DM) is a metabolic disorder characterized by the destruction of pancreatic β cells or diminished insulin secretion and action insulin. Obesity causes the development of metabolic disorders such as DM, hypertension, cardiovascular diseases, and inflammation-based pathologies. Flavonoids are the secondary metabolites of plants and have 15-carbon skeleton structures containing two phenyl rings and a heterocyclic ring. More than 5000 naturally occurring flavonoids have been reported from various plants and have been found to possess many beneficial effects with advantages over chemical treatments. A number of studies have demonstrated the potential health benefits of natural flavonoids in treating obesity and DM, and show increased bioavailability and action on multiple molecular targets. This review summarizes the current progress in our understanding of the anti-obesity and anti-diabetic potential of natural flavonoids and their molecular mechanisms for preventing and/or treating obesity and diabetes.

Genistein ameliorated endothelial nitric oxidase synthase uncoupling by stimulating sirtuin-1 pathway in ox-LDL-injured HUVECs

Endothelial nitric oxidase synthase (eNOS) uncoupling plays a causal role in endothelial dysfunction in atherosclerosis. Genistein consumption has been associated with the prevention of atherosclerosis. However, the effect of genistein on eNOS uncoupling has not been reported. A model of oxidized low-density lipoprotein (ox-LDL)-induced injury on human umbilical vein endothelial cells (HUVECs) was established to evaluate the effect of genistein on eNOS uncoupling. We investigated the effect of genistein on NADPH oxidase-dependent superoxide production, NOX4 expression, BH4 synthesis and oxidation, the expression of GTP cyclohydrolase 1 (GCH1) and dihydrofolate reductase (DHFR). The results showed that genistein decreased superoxide production and NOX4 expression, enhanced the ratio of BH4/BH2, augmented the expressions of GCH1 and DHFR. Accompanied with genistein ameliorating eNOS uncoupling, genistein elevated the expression of sirtuin-1; furthermore, the effects of genistein on eNOS uncoupling were blunted with sirtuin-1 siRNA. The present study indicated that genistein ameliorated eNOS uncoupling was concerned with sirtuin-1 pathway in ox-LDL-injured HUVECs.

Antidiabetic properties of dietary flavonoids: a cellular mechanism review

Background

Natural food products have been used for combating human diseases for thousands of years. Naturally occurring flavonoids including flavones, flavonols, flavanones, flavonols, isoflavones and anthocyanidins have been proposed as effective supplements for management and prevention of diabetes and its long-term complications based on in vitro and animal models.

Aim

To summarize the roles of dietary flavonoids in diabetes management and their molecular mechanisms.

Findings

Tremendous studies have found that flavonoids originated from foods could improve glucose metabolism, lipid profile, regulating the hormones and enzymes in human body, further protecting human being from diseases like obesity, diabetes and their complications.

Conclusion

In the current review, we summarize recent progress in understanding the biological action, mechanism and therapeutic potential of the dietary flavonoids and its subsequent clinical outcomes in the field of drug discovery in management of diabetes mellitus.

Ceramide-Initiated Protein Phosphatase 2A Activation Contributes to Arterial Dysfunction In Vivo

Prior studies have implicated accumulation of ceramide in blood vessels as a basis for vascular dysfunction in diet-induced obesity via a mechanism involving type 2 protein phosphatase (PP2A) dephosphorylation of endothelial nitric oxide synthase (eNOS). The current study sought to elucidate the mechanisms linking ceramide accumulation with PP2A activation and determine whether pharmacological inhibition of PP2A in vivo normalizes obesity-associated vascular dysfunction and limits the severity of hypertension. We show in endothelial cells that ceramide associates with the inhibitor 2 of PP2A (I2PP2A) in the cytosol, which disrupts the association of I2PP2A with PP2A leading to its translocation to the plasma membrane. The increased association between PP2A and eNOS at the plasma membrane promotes dissociation of an Akt-Hsp90-eNOS complex that is required for eNOS phosphorylation and activation. A novel small-molecule inhibitor of PP2A attenuated PP2A activation, prevented disruption of the Akt-Hsp90-eNOS complex in the vasculature, preserved arterial function, and maintained normal blood pressure in obese mice. These findings reveal a novel mechanism whereby ceramide initiates PP2A colocalization with eNOS and demonstrate that PP2A activation precipitates vascular dysfunction in diet-induced obesity. Therapeutic strategies targeted to reducing PP2A activation might be beneficial in attenuating vascular complications that exist in the context of type 2 diabetes, obesity, and conditions associated with insulin resistance.

Effects of Tomato and Soy Germ on Lipid Bioaccumulation and Atherosclerosis in ApoE-/- Mice

Dietary patterns with cardiovascular benefits have been recommended, but the relative contributions of individual foods and food components, alone or in combination, remain undefined. Male ApoE(-/-) mice were fed either a purified AIN-93G control diet, a Western diet (WD), or a WD with 10% tomato powder (TP), 2% soy germ (SG), or the combination, for 4 wk (n = 10 per group). Plasma total cholesterol and triglycerides were measured with enzymatic colorimetric kits, and serum amyloid A (SAA) was measured by ELISA. Liver lipids were extracted with chloroform:methanol, and triglycerides, free and esterified cholesterol measured with enzymatic colorimetric kits. Expression of Cyp27a1, Cyp7a1, Abcg5, and Abcg8 in the liver was determined by quantitative polymerase chain reaction. Sections of the aortic root and aorta were cut and stained with hematoxylin and eosin (H&E) to assess extent of atherosclerotic lesions. WD-fed animals had greater liver and adipose weights, plasma cholesterol and SAA, hepatic lipids, and atherosclerosis than AIN-93G animals. TP and SG did not decrease atherosclerosis as measured by H&E-stained sections of the aortic root, aortic arch, and descending aorta. The TP diets further increased plasma cholesterol, but also led to increased expression of the Abcg5/8 transporters involved in cholesterol efflux. Addition of SG alone to the WD attenuated WD-induced increases in plasma cholesterol, liver lipids, and gonadal adipose weight. The results of this study do not support the use of either TP or SG for reduction of atherosclerosis, but suggest some beneficial effects of SG on lipid metabolism in this model of cardiovascular disease.

A combination of isolated phytochemicals and botanical extracts lowers diastolic blood pressure in a randomized controlled trial of hypertensive subjects

BACKGROUND/OBJECTIVES

Isolated phytochemicals have been shown to reduce blood pressure; however, combinations of phytochemicals have rarely been tested in humans. We hypothesized that a combination of extracts from grape seed and skin (330 mg), green tea (100 mg), resveratrol (60 mg) and a blend of quercetin, ginkgo biloba and bilberry (60 mg) would reduce blood pressure (BP) in hypertensive subjects.

SUBJECTS/METHODS

Eighteen individuals meeting BP requirements (⩾130 mm Hg systolic or ⩾85 mm Hg diastolic) and criteria for metabolic syndrome were enrolled in a double-blinded, placebo-controlled, crossover trial (ClinicalTrials.gov, NCT01106170). The 28-day placebo and supplement arms were separated by a 2-week washout period, and 14 -h daytime ambulatory BP was assessed at baseline and at the end point of each arm.

RESULTS

BP was not altered after placebo. After supplement treatment, diastolic pressure was reduced by 4.4 mm Hg (P=0.024, 95% CI, 0.6-8.1), systolic pressure was unchanged and mean arterial pressure trended (P=0.052) toward reduction. Serum angiotensin-converting enzyme activity was similar between placebo and supplement arms, but urinary nitrate and nitrite concentrations were significantly increased (P=0.022) after supplementation. Human aortic endothelial cells treated with metabolites of the polyphenols used in the human supplement trial had a significant increase (P=0.005) in insulin-stimulated eNOS phosphorylation and greater (P<0.001) accumulation of nitrates/nitrites.

CONCLUSIONS

Our clinical and in vitro data support the theory that this combination of polyphenols reduced diastolic pressure by potentiating eNOS activation and nitric oxide production. Such supplements may have clinical relevance as stand-alone or adjunct therapy to help reduce BP.

GRID and docking analyses reveal a molecular basis for flavonoid inhibition of Src family kinase activity

Flavonoids reduce cardiovascular disease risk through anti-inflammatory, anti-coagulant and anti-platelet actions. One key flavonoid inhibitory mechanism is blocking kinase activity that drives these processes. Flavonoids attenuate activities of kinases including phosphoinositide-3-kinase, Fyn, Lyn, Src, Syk, PKC, PIM1/2, ERK, JNK and PKA. X-ray crystallographic analyses of kinase-flavonoid complexes show that flavonoid ring systems and their hydroxyl substitutions are important structural features for their binding to kinases. A clearer understanding of structural interactions of flavonoids with kinases is necessary to allow construction of more potent and selective counterparts. We examined flavonoid (quercetin, apigenin and catechin) interactions with Src family kinases (Lyn, Fyn and Hck) applying the Sybyl docking algorithm and GRID. A homology model (Lyn) was used in our analyses to demonstrate that high-quality predicted kinase structures are suitable for flavonoid computational studies. Our docking results revealed potential hydrogen bond contacts between flavonoid hydroxyls and kinase catalytic site residues. Identification of plausible contacts indicated that quercetin formed the most energetically stable interactions, apigenin lacked hydroxyl groups necessary for important contacts and the non-planar structure of catechin could not support predicted hydrogen bonding patterns. GRID analysis using a hydroxyl functional group supported docking results. Based on these findings, we predicted that quercetin would inhibit activities of Src family kinases with greater potency than apigenin and catechin. We validated this prediction using in vitro kinase assays. We conclude that our study can be used as a basis to construct virtual flavonoid interaction libraries to guide drug discovery using these compounds as molecular templates.

Protective effects of genistein in homocysteine-induced endothelial cell inflammatory injury

Hyperhomocysteinemia is a risk factor for cardiovascular disease and the mechanism of homocysteine (HCY)-induced vascular endothelial cell injury has been intensively studied for many years. Recently, a large number of studies have shown inhibitory effects of genistein (GEN), a soy isoflavone, in the process of endothelial cell injury. In the present study, the protective effects of GEN in HCY-induced endothelial cell inflammatory injury were investigated. A model of HCY-induced endothelial cell (ECV-304) inflammatory injury was established in vitro, and the protective effect of GEN in this procession was explored. According to our results, GEN protected HCY-induced endothelial cell from viability decreases, meanwhile prevented the changes of cell morphology and the production of reactive oxygen species (ROS). The expression of NF-kB P-65, IL-6, and ICAM-1 was all down-regulated. During the HCY-induced endothelial cell injury, the endothelial cell apoptosis and proliferation disorder were alleviated. Therefore, we conclude that HCY-induced endothelial cell inflammatory injury could be blocked by GEN. The present findings suggest that GEN protects HCY-induced endothelial cell inflammatory injury may through reducing the release of ROS, inhibiting NF-kB activation, down-regulating the expression of cytokine IL-6 and adhesion molecules ICAM-1, avoiding inflammatory cells and platelet adhesion, accordingly, leading to a balance of endothelial cell proliferation and apoptosis.