stilbenes and Diabetes-Mellitus--Type-2

Viniferin is a phenolic compound belonging to the group of stilbenoids. In particular, ε-viniferin is a dimer of resveratrol, found in many plant genders, among which grapes (

Topics: Animals; Diabetes Mellitus, Type 2; Female; Humans; Male; Mice; Obesity; Resveratrol; Stilbenes; Vitis

Type II diabetes mellitus and its related complications are growing public health problems. Many natural products present in our diet, including polyphenols, can be used in treating and managing type II diabetes mellitus and different diseases, owing to their numerous biological properties. Anthocyanins, flavonols, stilbenes, curcuminoids, hesperidin, hesperetin, naringenin, and phenolic acids are common polyphenols found in blueberries, chokeberries, sea-buckthorn, mulberries, turmeric, citrus fruits, and cereals. These compounds exhibit antidiabetic effects through different pathways. Accordingly, this review presents an overview of the most recent developments in using food polyphenols for managing and treating type II diabetes mellitus, along with various mechanisms. In addition, the present work summarizes the literature about the anti-diabetic effect of food polyphenols and evaluates their potential as complementary or alternative medicines to treat type II diabetes mellitus. Results obtained from this survey show that anthocyanins, flavonols, stilbenes, curcuminoids, and phenolic acids can manage diabetes mellitus by protecting pancreatic β-cells against glucose toxicity, promoting β-cell proliferation, reducing β-cell apoptosis, and inhibiting α-glucosidases or α-amylase. In addition, these phenolic compounds exhibit antioxidant anti-inflammatory activities, modulate carbohydrate and lipid metabolism, optimize oxidative stress, reduce insulin resistance, and stimulate the pancreas to secrete insulin. They also activate insulin signaling and inhibit digestive enzymes, regulate intestinal microbiota, improve adipose tissue metabolism, inhibit glucose absorption, and inhibit the formation of advanced glycation end products. However, insufficient data are available on the effective mechanisms necessary to manage diabetes.

Topics: Anthocyanins; Antioxidants; Diabetes Mellitus, Type 2; Diarylheptanoids; Flavonols; Glucose; Humans; Hypoglycemic Agents; Insulin; Polyphenols; Stilbenes

Pterostilbene, a phenolic compound derived from resveratrol, possesses greater bioavailability than its parent compound due to the presence of two methoxyl groups. In this review, the beneficial effects of pterostilbene on diabetes, liver steatosis and dyslipidemia are summarized. Pterostilbene is a useful bioactive compound in preventing type 1 diabetes, insulin resistance and type 2 diabetes in animal models. Concerning type 1 diabetes, the main mechanisms described to justify the positive effects of this phenolic compound are increased liver glycogen content and hepatic glucokinase and phosphofructokinase activities, the recovery of pancreatic islet architecture, cytoprotection and a decrease in serum and pancreatic pro-inflammatory cytokines. As for type 2 diabetes, increased liver glucokinase and glucose-6-phosphatase and decreased fructose-1,6-biphosphatase activities are reported. When insulin resistance is induced by diets, a greater activation of insulin signaling cascade has been reported, increased cardiotrophin-1 levels and liver glucokinase and glucose- 6-phosphatase activities, and a decreased fructose-1,6-biphosphatase activity. Data concerning pterostilbene and liver steatosis are scarce so far, but the reduction in oxidative stress induced by pterostilbene may be involved since oxidative stress is related to the progression of steatosis to steatohepatitis. Finally, pterostilbene effectively reduces total cholesterol, LDL-cholesterol and serum triglyceride levels, while increases HDL-cholesterol in animal models of dyslipidemia.

Topics: Animals; Diabetes Mellitus, Type 2; Fatty Liver; Humans; Insulin Resistance; Lipids; Liver; Stilbenes

Functional foods describe the importance of foods in promoting health and preventing diseases aside their primary role of providing the body with the required amount of essential nutrients such as proteins, carbohydrates, vitamins, fats, and oils needed for its healthy survival. This review explains the interaction of functional food bioactive compounds including polyphenols (phenolic acids [hydroxybenzoic acids and hydroxycinnamic acids], flavonoids [flavonols, flavones, flavanols, flavanones, isoflavones, proanthocyanidins], stilbenes, and lignans), terpenoids, carotenoids, alkaloids, omega-3 and polyunsaturated fatty acids, among others with critical enzymes (α- amylase, α- glucosidase, angiotensin-I converting enzyme [ACE], acetylcholinesterase [AChE], and arginase) linked to some degenerative diseases (type-2 diabetes, cardiovascular diseases [hypertension], neurodegenerative diseases [Alzheimer's disease] and erectile dysfunction). Different functional food bioactive compounds may synergistically/additively confer an overwhelming protection against these degenerative diseases by modulating/altering the activities of these critical enzymes of physiological importance.

Topics: Alkaloids; Cardiovascular Diseases; Carotenoids; Chronic Disease; Diabetes Mellitus, Type 2; Dietary Supplements; Erectile Dysfunction; Flavonoids; Functional Food; Health Promotion; Humans; Lignans; Male; Neurodegenerative Diseases; Nutritional Requirements; Phenols; Polyphenols; Stilbenes

Resveratrol (RES), a well-known antioxidant, is present in numerous plant species and, as a result, is easily obtained through dietary intake of plant-based foods and beverages. Several studies suggest that RES has anti-carcinogenic, anti-microbial, and anti-viral effects. It may also have beneficial metabolic properties that result in mitigation of insulin resistance (IR) and related metabolic abnormalities, including dyslipidemia, hyperglycemia, and hyperinsulinemia through regulation of gene expression or the activity of rate-limiting enzymes. A large body of evidence supports the beneficial effects of RES in the management and treatment of IR, type 2 diabetes, and related complications through a multitude of mechanisms. This review article focuses on the mechanisms of action of RES, the mechanisms leading to improved insulin sensitivity, and its clinical role in the management and treatment of type 2 diabetes.

Topics: Animals; Blood Glucose; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Humans; Insulin Resistance; Mice; Resveratrol; Signal Transduction; Stilbenes

Monocyte chemoattractant protein-1 (MCP-1) is a member of the CC chemokine family that plays a key role in the inflammatory process. It has been broadly studied in the aspect of its role in obesity and diabetes related diseases. MCP-1 causes the infiltration of macrophages into obese adipose tissue via binding to the CCR2 receptor and is involved in the development of insulin resistance.. We reviewed the available literature regarding the importance of plant metabolites that regulate MCP-1 activity and are used in the treatment of diabetic disorders. The characteristics of screened papers were described and the important findings were included in this review.. This mini-review provides a summary of functions and therapeutic strategies of this chemokine, with a special focus on plant-derived compounds that possess a putative antidiabetic function via a mechanism of MCP-1 interaction. The highlights of this review include the roles of MCP-1 in development of diabetes, the evaluation of plant metabolites that specifically or non-specifically inhibit MCP-1 overproduction, and the molecular mechanisms of this activity. Among these metabolites, we particularly focused on phenolic acids and their derivatives, flavonoids, stilbenes, anthocyanins, capsaicin, alkaloids, plant sterols, terpenes, saponins, unsaturated fatty acids and plant-derived extracts.. Regarding the increasing number of diabetic patients yearly, the recent progress in the putative therapies needs to be summarized. This article underlines the significance and involvement of the chemokine MCP-1 in the development of obesity, type 2 diabetes, and diabetic complications, with an emphasis on the role of plant metabolites in the regulation of this chemokine and thus the role in the prevention or therapy of diabetes. We suggest that MCP-1 might be a molecular marker of type 2 diabetes.

Topics: Alkaloids; Animals; Anthocyanins; Capsaicin; Chemokine CCL2; Diabetes Complications; Diabetes Mellitus, Type 2; Flavonoids; Humans; Phenols; Plant Extracts; Sterols; Stilbenes; Terpenes

Resveratrol-a polyphenol of natural origin-has been the object of massive research in the past decade because of its potential use in cancer therapy. However, resveratrol has shown an extensive range of cellular targets and effects, which hinders the use of the molecule for medical applications including cancer and type 2 diabetes. Here, we review the latest advances in understanding how resveratrol modulates glucose uptake, regulates cellular metabolism, and how this may be useful to improve current therapies. We discuss challenges and findings regarding the inhibition of glucose uptake by resveratrol and other polyphenols of similar chemical structure. We review alternatives that can be exploited to improve cancer therapies, including the use of other polyphenols, or the combination of resveratrol with other molecules and their impact on glucose homeostasis in cancer and diabetes.

Topics: Animals; Antineoplastic Agents, Phytogenic; Biological Transport; Carbohydrate Metabolism; Diabetes Mellitus, Type 2; Drug Synergism; Glucose; Homeostasis; Humans; Neoplasms; Polyphenols; Resveratrol; Signal Transduction; Stilbenes

Fibrillar aggregates of human islet amyloid polypeptide, hIAPP, a pathological feature seen in some diabetes patients, are a likely causative agent for pancreatic beta-cell toxicity, leading to a transition from a state of insulin resistance to type II diabetes through the loss of insulin producing beta-cells by hIAPP induced toxicity. Because of the probable link between hIAPP and the development of type II diabetes, there has been strong interest in developing reagents to study the aggregation of hIAPP and possible therapeutics to block its toxic effects. Natural products are a class of compounds with interesting pharmacological properties against amyloids which have made them interesting targets to study hIAPP. Specifically, the ability of polyphenolic natural products, EGCG, curcumin, and resveratrol, to modulate the aggregation of hIAPP is discussed. Furthermore, we have outlined possible mechanistic discoveries of the interaction of these small molecules with the peptide and how they may mitigate toxicity associated with peptide aggregation. These abundantly found agents have been long used to combat diseases for many years and may serve as useful templates toward developing therapeutics against hIAPP aggregation and toxicity.

Topics: Catechin; Curcumin; Diabetes Mellitus, Type 2; Humans; Insulin-Secreting Cells; Islet Amyloid Polypeptide; Resveratrol; Stilbenes

Flavonoid resveratrol modulates the transcription factor NF-κB; inhibits the cytochrome P450 isoenzyme CYP1 A1; suppresses the expression and activity of cyclooxygenase enzymes; and modulates Fas/Fas-ligand-mediated apoptosis, p53, mammalian target of rapamycin, and cyclins and various phosphodiesterases. This increases the cytosolic cAMP that activates Epac1/CaMKKβ/AMPK/SIRT1/PGC-1α pathway, which in turn facilitates increased oxidation of fatty acids, mitochondrial biogenesis, mitochondrial respiration, and gluconeogenesis. Resveratrol triggers apoptosis of activated T cells and suppresses tumor necrosis factor-α, interluekin-17 (IL-17), and other proinflammatory molecules, and thus is of benefit in autoimmune diseases. In addition, resveratrol inhibits expression of hypoxia-inducible factor-1α and vascular endothelial growth factor, explaining its effective action against cancer. Brain-derived neurotrophic factor (BDNF) that is involved in the pathogenesis of obesity, type 2 diabetes mellitus, and metabolic syndrome is also altered in depression, schizophrenia, bipolar disorder, and autism. We noted that BDNF protects against cytotoxic actions of alloxan, streptozotocin, and benzo(a)pyrene. Resveratrol prevents bisphenol A-induced autism, type 2 diabetes mellitus, and metabolic syndrome, suggesting that it may augment BDNF synthesis and action. We also observed that BDNF levels are low in type 2 diabetes mellitus and that BDNF enhances production of antiinflammatory lipid, lipoxin A4, whose levels are low in diabetes mellitus. Thus, resveratrol may augment production of lipoxin A4. Resveratrol alters gut microbiota and influences stem cell proliferation and differentiation. These pleiotropic actions of resveratrol may explain the multitude of its actions and benefits.

Topics: Anti-Inflammatory Agents, Non-Steroidal; Antioxidants; Apoptosis; Autistic Disorder; Brain-Derived Neurotrophic Factor; Cell Differentiation; Cell Proliferation; Cytochrome P-450 CYP1A1; Diabetes Mellitus, Type 2; Gastrointestinal Microbiome; Gastrointestinal Tract; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Interleukin-17; Lipoxins; Metabolic Syndrome; NF-kappa B; Resveratrol; Stilbenes; Transcription Factors; Tumor Necrosis Factor-alpha; Vascular Endothelial Growth Factor A

The red wine polyphenol, resveratrol, is highly effective in treating type 2 diabetes mellitus (T2DM) in animal models, but there is no consensus regarding its efficacy in humans. We conducted a systematic review, which included searches in nine scholarly databases and six clinical trial registries, and identified randomized controlled clinical trials whereby resveratrol was used as an adjunct to pharmaceutical interventions in T2DM. Meta-analysis on clinical parameters was performed for available data. Of 764 articles originally identified, data from six unique datasets, examining a total of 196 T2DM patients (104 resveratrol, 92 control/placebo) ultimately met inclusion criteria. Statistically significant (p < 0.05) positive effects, indicating that resveratrol supplementation was more effective than placebo/control, were identified for systolic blood pressure, hemoglobin A1c, and creatinine, but not for fasting glucose, homeostatic model assessment of insulin resistance, diastolic blood pressure, insulin, triglycerides, LDL, or HDL cholesterol. No major adverse events were reported and side effects of resveratrol were not different than placebo/control. Though limitations in sample size and treatment duration preclude definitive changes in clinical practice, significant improvements in multiple cardiometabolic biomarkers and an excellent safety profile support resveratrol as a leading candidate as an adjunct to pharmacological management of T2DM.

Topics: Blood Pressure; Cholesterol, HDL; Cholesterol, LDL; Creatinine; Databases, Factual; Diabetes Mellitus, Type 2; Dietary Supplements; Glycated Hemoglobin; Humans; Insulin; Randomized Controlled Trials as Topic; Resveratrol; Stilbenes; Triglycerides

Polyphenols are members of a very large family of plant-derived compounds that may have beneficial effects on human health, and thus their study has become an increasingly important area of human nutrition research. Considering that it is increasingly accepted that chronic sub-acute inflammation plays an important role in the development of insulin resistance and of diabetes in animals and in humans, the aim of the present review is to compile information concerning the anti-inflammatory effects of non-flavonoid polyphenols on diabetes prevention and/or treatment. Most of these studies have been carried out with different cultured cells and using animal models displaying different types of diabetes, such as diabetes induced by streptozotocin or streptozotocin-nicotinamide, genetic diabetes or diabetes induced by high-fat feeding. In general terms, non-flavonoid polyphenols reduce the production of inflammatory mediators, such as IL-1β, IL-8, MCP-1, COX-2 or iNOS in these animal models of diabetes. This effect is accompanied in the vast majority of these studies by improved insulin action. In addition, some of the non-flavonoid polyphenols are also able to ameliorate or prevent several pathological alterations associated with the development of diabetes, such as nephropathy, cardiopathy or retinopathy. Very little information has been reported with regard to human studies to date. Thus, new studies are needed to confirm if the beneficial effects observed in preclinical studies can apply to human beings.

Topics: Animals; Anti-Inflammatory Agents; Clinical Trials as Topic; Curcumin; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Disease Models, Animal; Humans; Hydroxybenzoates; Phenols; Polyunsaturated Alkamides; Stilbenes

Resveratrol, a polyphenol found in a number of plant-based foods such as red wine, has received a great deal of attention for its diverse array of healthful effects. Beneficial effects of resveratrol are diverse; they include improvement of mitochondrial function, protection against obesity and obesity-related diseases such as type-2 diabetes, suppression of inflammation and cancer cell growth and protection against cardiovascular dysfunction, just to name a few. Investigations into the metabolic effects of resveratrol are furthest along and now include a number of clinical trials, which have yielded mixed results. There are a number of controversies surrounding resveratrol that have not been resolved. Here, we will review these controversies with particular emphasis on its mechanism of metabolic action and how lessons from resveratrol may help develop therapies that harness the effects of resveratrol but without the undesirable properties of resveratrol.

Topics: AMP-Activated Protein Kinases; Animals; Antioxidants; Cyclic Nucleotide Phosphodiesterases, Type 4; Diabetes Mellitus, Type 2; Humans; Longevity; Neuroprotective Agents; Obesity; Resveratrol; Signal Transduction; Sirtuin 1; Stilbenes

Civilization development is associated with immense progress in science and significant improvement of human living conditions but simultaneously it contributes to many health problems including metabolic syndrome. Metabolic syndrome is a set of mutually associated factors including insulin resistance, hyperinsulinemia, obesity, lipids disorders and hypertension, which is the main cause of development of coronary heart disease and type 2 diabetes. The first line of defense against metabolic syndrome is a change of life style including body mass reduction, application of a low-calorie diet and performance of physical activity. In spite of the simplicity of therapy, long-term success of the above treatment among patients is observed seldom because it is very difficult to obey rigorous rules. Nowadays, it is considered that diet supplements including antioxidants, polyunsaturated fatty acids and mineral elements are helpful in metabolic syndrome treatment due to their antioxidant and anti-inflammatory properties. It is considered that a health balanced diet enriched with various diet supplements may be the best strategy in metabolic syndrome treatment.

Topics: Animals; Anti-Inflammatory Agents; Antioxidants; Calcium; Caloric Restriction; Diabetes Mellitus, Type 2; Dietary Supplements; Fatty Acids, Omega-3; Garlic; Humans; Magnesium; Metabolic Syndrome; Obesity; Panax; Photinia; Phytotherapy; Plant Preparations; Resveratrol; Risk Reduction Behavior; Selenium; Stilbenes; Tea; Zinc

Numerous studies have highlighted the key roles of oxidative stress and inflammation in aging-related diseases such as obesity, type 2 diabetes, age-related macular degeneration (AMD), and Alzheimer's disease (AD). In aging cells, the natural antioxidant capacity decreases and the overall efficiency of reparative systems against cell damage becomes impaired. There is convincing data that stilbene compounds, a diverse group of natural defence phenolics, abundant in grapes, berries, and conifer bark waste, may confer a protective effect against aging-related diseases. This review highlights recent data helping to clarify the molecular mechanisms involved in the stilbene-mediated protection against oxidative stress. The impact of stilbenes on the nuclear factor-erythroid-2-related factor-2 (Nrf2) mediated cellular defence against oxidative stress as well as the potential roles of SQSTM1/p62 protein in Nrf2/Keap1 signaling and autophagy will be summarized. The therapeutic potential of stilbene compounds against the most common aging-related diseases is discussed.

Topics: Adaptor Proteins, Signal Transducing; Diabetes Mellitus, Type 2; Humans; Neurodegenerative Diseases; NF-E2-Related Factor 2; Obesity; Oxidative Stress; Polyphenols; Reactive Oxygen Species; Signal Transduction; Stilbenes

The number of people suffering from metabolic diseases is dramatically increasing worldwide. This stresses the need for new therapeutic strategies to combat this growing epidemic of metabolic diseases. A reduced mitochondrial function is one of the characteristics of metabolic diseases and therefore a target for intervention. Here we review the evidence that mitochondrial function may act as a target to treat and prevent type 2 diabetes mellitus, and, if so, whether these effects are due to reduction in skeletal muscle fat accumulation. We describe how exercise may affect these parameters and can be beneficial for type 2 diabetes. We next focus on alternative ways to improve mitochondrial function in a non-exercise manner. Thus, in 2003, resveratrol (3,5,4'-trihydroxystilbene) was discovered to be a small molecule activator of sirtuin 1, an important molecular target regulating cellular energy metabolism and mitochondrial homoeostasis. Rodent studies have clearly demonstrated the potential of resveratrol to improve various metabolic health parameters. Here we review data in human subjects that is available on the effects of resveratrol on metabolism and mitochondrial function and discuss how resveratrol may serve as a new therapeutic strategy to preserve metabolic health. We also discuss whether the effects of resveratrol are similar to the effects of exercise training and therefore if resveratrol can be considered as an exercise mimetic.

Topics: Adipose Tissue; Diabetes Mellitus, Type 2; Energy Metabolism; Enzyme Activators; Exercise; Humans; Mitochondria; Muscle, Skeletal; Resveratrol; Sirtuin 1; Stilbenes

Overproduction of hepatic apoB100-containing VLDL particles has been well documented in animal models and in humans with insulin resistance such as the metabolic syndrome and type 2 diabetes, and contributes to the typical dyslipidemia of these conditions. In addition, postprandial hyperlipidemia and elevated plasma concentrations of intestinal apoB48-containing chylomicron and chylomicron remnant particles have been demonstrated in insulin resistant states. Intestinal lipoprotein production is primarily determined by the amount of fat ingested and absorbed. Until approximately 10 years ago, however, relatively little attention was paid to the role of the intestine itself in regulating the production of triglyceride-rich lipoproteins (TRL) and its dysregulation in pathological states such as insulin resistance. We and others have shown that insulin resistant animal models and humans are characterized by overproduction of intestinal apoB48-containing lipoproteins. Whereas various factors are known to regulate hepatic lipoprotein particle production, less is known about factors that regulate the production of intestinal lipoprotein particles. Monosacharides, plasma free fatty acids (FFA), resveratrol, intestinal peptides (e.g. GLP-1 and GLP-2), and pancreatic hormones (e.g. insulin) have recently been shown to be important regulators of intestinal lipoprotein secretion. Available evidence in humans and animal models strongly supports the concept that the small intestine is not merely an absorptive organ but rather plays an active role in regulating the rate of production of chylomicrons in fed and fasting states. Metabolic signals in insulin resistance and type 2 diabetes and in some cases an aberrant intestinal response to these factors contribute to the enhanced formation and secretion of TRL. Understanding the regulation of intestinal lipoprotein production is imperative for the development of new therapeutic strategies for the prevention and treatment of dyslipidemia. Here we review recent developments in this field and present evidence that intestinal lipoprotein production is a process with metabolic plasticity and that modulation of intestinal lipoprotein secretion may be a feasible therapeutic strategy in the treatment of dyslipidemia and possibly prevention of atherosclerosis.

Topics: Animals; Apolipoprotein B-100; Apolipoprotein B-48; Atherosclerosis; Bile Acids and Salts; Cholesterol; Chylomicrons; Clinical Trials as Topic; Diabetes Mellitus, Type 2; Dietary Carbohydrates; Dietary Fats; Dipeptidyl-Peptidase IV Inhibitors; Drug Evaluation, Preclinical; Dyslipidemias; Exenatide; Fatty Acids, Nonesterified; Glucagon-Like Peptide 1; Glucagon-Like Peptide 2; Glucagon-Like Peptide-1 Receptor; Humans; Incretins; Insulin; Insulin Resistance; Intestine, Small; Lipoproteins; Microbiota; Peptides; Receptors, Glucagon; Resveratrol; Secretory Rate; Stilbenes; Triglycerides; Venoms

Adiponectin is produced predominantly by adipocytes and plays an important role in metabolic and cardiovascular homeostasis through its insulin-sensitizing actions and anti-inflammatory and anti-atherogenic properties. Recently, it has been observed that lower levels of adiponectin can substantially increase the risk of developing type 2 diabetes, metabolic syndrome, atherosclerosis, and cardiovascular disease in patients who are obese. Circulating adiponectin levels are inversely related to the inflammatory process, oxidative stress, and metabolic dysregulation. Intensive lifestyle modifications and pharmacologic agents, including peroxisome proliferator-activated receptor-γ or α agonists, some statins, renin-angiotensin-aldosterone system blockers, some calcium channel blockers, mineralocorticoid receptor blockers, new β-blockers, and several natural compounds can increase adiponectin levels and suppress or prevent disease initiation or progression, respectively, in cardiovascular and metabolic disorders. Therefore, it is important for investigators to have a thorough understanding of the interventions that can modulate adiponectin. Such knowledge may lead to new therapeutic approaches for diseases such as type 2 diabetes, metabolic syndrome, cardiovascular disease, and obesity. This review focuses on recent updates regarding therapeutic interventions that might modulate adiponectin.

Topics: Adiponectin; Antihypertensive Agents; Atherosclerosis; Bariatric Surgery; Cardiovascular Diseases; Clinical Trials as Topic; Combined Modality Therapy; Diabetes Mellitus, Type 2; Diet, Reducing; Exercise; Humans; Hypoglycemic Agents; Insulin Resistance; Life Style; Metabolic Syndrome; Metabolism, Inborn Errors; Obesity; Peroxisome Proliferator-Activated Receptors; Receptors, Adiponectin; Resveratrol; Stilbenes

The results of human clinical trials investigating the effects of resveratrol on glucose control and insulin sensitivity are inconsistent.. We aimed to quantitatively evaluate the effects of resveratrol on glucose control and insulin sensitivity.. We performed a strategic literature search of PubMed, Embase, MEDLINE, and the Cochrane Library (updated to March 2014) for randomized controlled trials that estimated the effects of resveratrol on glucose control and insulin sensitivity. Study quality was assessed by using the Jadad scale. Weighted mean differences were calculated for net changes in glycemic measures by using fixed-effects or random-effects models. We performed prespecified subgroup and sensitivity analyses to evaluate potential heterogeneity. Meta-regression analyses were conducted to investigate dose effects of resveratrol on fasting glucose and insulin concentrations in nondiabetic subjects.. Eleven studies comprising a total of 388 subjects were included in this meta-analysis. Resveratrol consumption significantly reduced fasting glucose, insulin, glycated hemoglobin, and insulin resistance (measured by using the homeostatic model assessment) levels in participants with diabetes. No significant effect of resveratrol on glycemic measures of nondiabetic participants was found in the meta-analysis. Subgroup and sensitivity analyses indicated that the pooled effects of resveratrol on fasting glucose and insulin concentrations in nondiabetic participants were not affected by body mass index, study design, resveratrol dose, study duration, or Jadad score.. Resveratrol significantly improves glucose control and insulin sensitivity in persons with diabetes but does not affect glycemic measures in nondiabetic persons. Additional high-quality studies are needed to further evaluate the potential benefits of resveratrol in humans.

Topics: Diabetes Mellitus, Type 2; Dietary Supplements; Humans; Hyperglycemia; Hypoglycemic Agents; Insulin Resistance; Randomized Controlled Trials as Topic; Resveratrol; Stilbenes

The number of people suffering from metabolic disorders is dramatically increasing worldwide. The need for new therapeutic strategies to combat this growing epidemic of metabolic diseases is therefore also increasing. In 2003, resveratrol was discovered to be a small molecule activator of sirtuin 1 (SIRT1), an important molecular target regulating cellular energy metabolism and mitochondrial homeostasis. Rodent studies have clearly demonstrated the potential of resveratrol to improve various metabolic health parameters. To date, however, only limited clinical data are available that have systematically examined the health benefits of resveratrol in metabolically challenged humans. This short review will give an overview of the currently available clinical studies examining the effects of resveratrol on obesity and type 2 diabetes from a human perspective.

Topics: Animals; Clinical Trials as Topic; Diabetes Mellitus, Type 2; Energy Metabolism; Humans; Insurance Benefits; Obesity; Resveratrol; Stilbenes

Resveratrol, a natural polyphenol abundantly found in grape skins and red wine, possesses diverse biochemical and physiological actions, including anti-inflammatory, anti-oxidation, anti-proliferation and promotion of differentiation, and chemopreventive effects. Recently, it is attracting increased attention due to its health benefits, especially in common age-related diseases such as cardiovascular disease, cancer, type 2 diabetes, and neurological conditions. In this review, we discuss the latest cellular and molecular findings that account for the beneficial actions of resveratrol.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Antineoplastic Agents; Antioxidants; Cardiovascular Diseases; Diabetes Mellitus, Type 2; Humans; Neurodegenerative Diseases; Platelet Aggregation Inhibitors; Resveratrol; Stilbenes

Diabetes mellitus is a complex metabolic disease affecting about 5% of people all over the world. Data from the literature indicate that resveratrol is a compound exerting numerous beneficial effects in organisms. Rodent studies, for example, have demonstrated that resveratrol decreases blood glucose in animals with hyperglycemia. This effect seems to predominantly result from increased intracellular transport of glucose. Resveratrol was also demonstrated to induce effects that may contribute to the protection of β cells in diabetes. In experiments on pancreatic islets, the ability of resveratrol to reduce insulin secretion was demonstrated; this effect was confirmed in animals with hyperinsulinemia, in which resveratrol decreased blood insulin levels. Moreover, inhibition of cytokine action and attenuation of the oxidative damage of the pancreatic tissue by resveratrol were recently shown. Studies of animals with insulin resistance indicate that resveratrol may also improve insulin action. The mechanism through which resveratrol improves insulin action is complex and involves reduced adiposity, changes in gene expression, and changes in the activities of some enzymes. These data indicate that resveratrol may be useful in preventing and treating diabetes.

Topics: Animals; Blood Glucose; Diabetes Mellitus; Diabetes Mellitus, Type 2; Humans; Hypoglycemic Agents; Insulin Resistance; Resveratrol; Stilbenes

To evaluate the role of mammalian Sirt1 and Sirt1 activators in the protection from metabolic disorders such as diet-induced obesity, diabetes type 2, or nonalcoholic fatty liver disease.. Sirtuins are highly conserved nicotinamide adenine dinucleotide (NAD+)-dependent deacetylases that are activated by NAD+ and inhibited by NAD in its reduced form (NADH). Sirtuins act as cellular energy sensors that deacetylate numerous proteins involved in energy and glucose homeostasis, which in turn induce a wide range of physiological changes that counteract detrimental effects of metabolic stressors.. Sirt1 targets numerous proteins, including peroxisome proliferator-activated receptor (PPAR)-gamma, PPAR-gamma coactivator (PGC)-1alpha, uncoupling protein 2 (UCP2), and nuclear factor-kappa B, which play key roles in various metabolic disorders. This review summarizes these key targets of Sirt1 and the physiological relevance of those interactions. Also, new results on Sirt1-knockout and overexpressor mouse models are presented to substantiate metabolic benefits from Sirt1 activation. Finally, this review gives an overview on recent efforts to activate Sirt1 pharmacologically by using resveratrol or small-molecule Sirt1 activators with improved biopotency.

Topics: AMP-Activated Protein Kinases; Animals; Caloric Restriction; Diabetes Mellitus, Type 2; Diet; Disease Models, Animal; Energy Metabolism; Humans; Mice; Mice, Transgenic; NAD; Resveratrol; Sirtuin 1; Sirtuins; Stilbenes; Trans-Activators; Transcription, Genetic

The metabolic syndrome (MetS) encompasses a constellation of cardio-metabolic abnormalities associated with a high risk of developing type 2 diabetes and cardiovascular disease (CVD), the top killer in the ageing population. Recent studies have demonstrated multiple beneficial effects of moderate wine consumption in the protection against development of the MetS and its related medical complications. The association of moderate wine consumption with lower incidence of the MetS and atherosclerotic heart disease has been repeatedly documented in numerous epidemiological studies on diverse ethnic groups. In addition to the favorable effects of moderate ethanol intake on lipid profiles, polyphenols enriched in red wine possess multiple benefits on the MetS beyond alcohol through their anti-oxidant, anti-inflammatory, vascular-protective and insulin-sensitizing properties. Notable among these red wine polypheolic compounds is resveratrol, a phytoalexin that has recently attracted great attention due to its role in mimicking calorie restriction. This compound can act as a potent activator of the NAD(+)-dependent deacetylases sirtuins to expand the life span and to prevent the deleterious effects of excess intake on insulin resistance and metabolic derangement. In addition, resveratrol exerts its multiple protective effects against the MetS through stimulating AMP-activated protein kinase and promoting mitochondria biogenesis. In this review, we highlight the recent epidemiological and experimental evidences supporting the protective effects of moderate wine intake against the MetS and its associated cardio-metabolic complications, and discuss the molecular mechanisms underlying the multiple beneficial actions of red wine polyphenols with the focus on resveratrol.

Topics: Alcohol Drinking; Animals; Antioxidants; Cardiovascular Diseases; Diabetes Mellitus, Type 2; Humans; Insulin Resistance; Metabolic Syndrome; Randomized Controlled Trials as Topic; Resveratrol; Stilbenes; Wine

Studies show that the plant polyphenol resveratrol can extend the life span of yeast, worms, flies, and fish. It also mitigates the metabolic dysfunction of mice fed high-fat diets. Resveratrol appears to mediate these effects partly by activating SIRT1, a deacetylase enzyme that regulates the activity of several transcriptional factors and enzymes responsive to nutrient availability. However, few foods contain resveratrol and humans metabolize it extensively, resulting in very low systemic bioavailability. Substantial research effort now focuses on identifying and testing more bioavailable and potent activators of SIRT1 for use as pharmacologic interventions in aging and age-related disorders.

Topics: Aging; Animals; Biological Availability; Cardiovascular Diseases; Diabetes Mellitus, Type 2; Enzyme Activation; Enzyme Activators; Humans; Inflammation; Neurodegenerative Diseases; Resveratrol; Sirtuin 1; Sirtuins; Stilbenes

Sirtuins represent a novel family of enzymes that are collectively well situated to help regulate nutrient sensing and utilization, metabolic rate and ultimately metabolic disease. Activation of one of these enzymes, SIRT1, leads to enhanced activity of multiple proteins, including peroxisome-proliferator activated receptor coactivator-1alpha (PGC-1alpha), which helps to mediate some of the in vitro and in vivo effects of sirtuins. As such, enhanced SIRT1 activity decreases glucose levels, improves insulin sensitivity, increases mitochondrial number and function, decreases adiposity, improves exercise tolerance and potentially lowers body weight. SRT-501 is a proprietary formulation of resveratrol with improved bioavailability. As such, SRT-501 represents the first in a novel class of SIRT1 activators that has proven to be safe and well-tolerated in humans. Clinical trials in type 2 diabetic patients are currently underway.

Topics: Base Sequence; Diabetes Mellitus, Type 2; Energy Metabolism; Enzyme Activators; Enzyme Inhibitors; Humans; Metabolic Diseases; Molecular Sequence Data; Molecular Structure; Obesity; Resveratrol; Sirtuin 1; Sirtuins; Stilbenes

Calyx Therapeutics is developing the insulin sensitizer, CLX-0901, as an antidiabetic agent. CLX-0901 is the synthetic analog of CLX-0900 which was originally isolated from a plant source. Phase I and toxicological studies indicate that the compound is safe and well tolerated [363764]. As of March 2001, phase II studies had commenced [402737]. Other antidiabetics being investigated by Calyx include CLX-0301, CLX-0921, CLX-0940, CLX-0100 and CLX-0101 [376032].

Topics: Animals; Clinical Trials as Topic; Contraindications; Diabetes Mellitus, Type 2; Humans; Hypoglycemic Agents; Insulin Resistance; Stilbenes; Structure-Activity Relationship

Obstetrical complications affect more than a third of women globally, but are underrepresented in clinical research. Little is known about the comprehensive obstetrical clinical trial landscape, how it compares with other fields, or factors associated with the successful completion of obstetrical trials.. This study aimed to characterize obstetrical clinical trials registered on ClinicalTrials.gov with the primary objective of identifying features associated with early discontinuation and results reporting.. This is a cross-sectional study with descriptive, logistic regression and Cox regression analyses of clinical trials registered on ClinicalTrials.gov. Our primary exposure variables were trial focus (obstetrical or nonobstetrical) and trial funding (industry, United States government, or academic). We conducted additional exploratory analyses of other trial features including design, enrollment, and therapeutic focus. We examined the associations of exposure variables and other trial features with 2 primary outcomes: early discontinuation and results reporting.. Obstetrical trials represent only 1.9% of all clinical trials in ClinicalTrials.gov and have comparatively poor completion. All stakeholders should commit to increasing the number of obstetrical trials and improving their completion and dissemination to ensure clinical research reflects the obstetrical burden of disease and advances maternal health.

Topics: Adipose Tissue, White; Adult; Aged; Air Pollutants; Animals; Anti-Inflammatory Agents; Arginine; bcl-2-Associated X Protein; Biofuels; Biological Products; Blood Glucose; Breast Neoplasms; Caspases; CD36 Antigens; Cell Communication; Cell Proliferation; Cell Survival; Cooking; Cross-Sectional Studies; Databases, Factual; Diabetes Mellitus, Type 2; Diphtheria Toxin; Double-Blind Method; Exenatide; Extracellular Polymeric Substance Matrix; Feasibility Studies; Female; Filgrastim; Fruit; Galactose; Gene Deletion; Gene Knockdown Techniques; Glucagon; Glucagon-Like Peptide-1 Receptor; Glucagon-Secreting Cells; Glucose; Glycated Hemoglobin; Hematopoietic Stem Cell Mobilization; Household Articles; Humans; Hypoglycemic Agents; Insulin; Insulin Secretion; Islets of Langerhans; Lung; Lymphoma; Male; Metals, Heavy; Mice; Mice, Inbred C57BL; Mice, Knockout; Middle Aged; Nanoparticles; Neoplasms; Obesity; Obstetrics; Odds Ratio; Oxygen; Peripheral Blood Stem Cell Transplantation; Photochemotherapy; Plant Extracts; Polyethylene Glycols; Polyglutamic Acid; Porosity; Postprandial Period; Prospective Studies; Quality of Life; Receptors, Glucagon; Receptors, LDL; Receptors, Somatostatin; Registries; Rhodophyta; Rhodotorula; Risk Factors; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Signal Transduction; Somatostatin; Stilbenes; Terminalia; Treatment Outcome; United States; Venoms

Sirtuin-1 (SIRT-1) down-regulation in type 2 diabetes mellitus (T2DM) has been associated with epigenetic markers of oxidative stress. We herein aim to evaluate whether an increase in SIRT-1 expression affects histone 3 acetylation at the 56 lysine residue (H3K56ac) in T2DM patients randomly selected to receive either resveratrol (40 mg or 500 mg) or a placebo for 6 months. The primary outcome is changes in the H3K56ac level by variation in SIRT-1 expression and the secondary outcome is the evidence of association between SIRT-1 level, antioxidant markers (TAS), and metabolic variables.. At baseline, peripheral blood mononuclear cell H3K56ac values among the SIRT-1 tertiles did not differ. At trial end, SIRT-1 levels were significantly higher in patients receiving 500 mg resveratrol. At follow-up, patients were divided into tertiles of delta (trial end minus baseline) SIRT-1 value. Significant reductions in H3K56ac and body fat percentage were found in the highest tertile as were increased TAS levels. A multiple logistic regression model showed that the highest delta SIRT-1 tertile was inversely associated with variations in H3K56ac (OR = 0.66; 95% CI 0.44-0.99), TAS (OR = 1.01; 95% CI 1.00-1.02), and body fat percentage (OR = 0.75; 95% CI 0.58-0.96).. We provide new knowledge on H3K56ac and SIRT-1 association in T2DM. These data suggest that boosting SIRT-1 expression/activation may impact redox homeostasis in these patients. ClinicalTrials.gov Identifier NCT02244879.

Topics: Acetylation; Adult; Aged; Antioxidants; Diabetes Mellitus, Type 2; Dietary Supplements; Double-Blind Method; Down-Regulation; Female; Histones; Humans; Leukocytes, Mononuclear; Male; Middle Aged; Oxidative Stress; Resveratrol; Sirtuin 1; Stilbenes

Oxidative stress plays a pivotal role in the pathogenesis of type 2 diabetes (T2D). In vitro and animal studies have shown that resveratrol exerts an antioxidant effect, but clinical trials addressing this effect in patients with T2D are limited. The aim of this study was to determine whether resveratrol supplementation affects oxidative stress markers in a randomized, placebo-controlled, double-blind clinical trial.. A total of 48 patients with T2D randomly were assigned to receive 800 mg/day resveratrol or placebo for 2 months. Plasma total antioxidant capacity, malondialdehyde concentration, protein carbonyl and total thiol contents, intracellular superoxide anion (O. Compared with the placebo group, resveratrol reduced plasma protein carbonyl content and PBMCs O. Our study demonstrated that 8 weeks of supplementation with 800 mg/day resveratrol has an antioxidant effect in the blood and PBMCs of patients with T2D. Clinical Trial Registry number and website IRCT registration number: IRCT2015072523336N1 and http://en.search.irct.ir/view/24752 .

Topics: Adult; Aged; Antioxidants; Biomarkers; Body Weight; C-Reactive Protein; Diabetes Mellitus, Type 2; Dietary Supplements; Double-Blind Method; Female; Humans; Hydrogen Peroxide; Male; Malondialdehyde; Middle Aged; Oxidative Stress; Placebos; Protein Carbonylation; Resveratrol; Stilbenes

Resveratrol has been reported to have potent anti-atherosclerotic effects in animal studies. However, there are few interventional studies in human patients with atherosclerogenic diseases. The cardio-ankle vascular index (CAVI) reflects arterial stiffness and is a clinical surrogate marker of atherosclerosis. The aim of the present study was to investigate the effect of resveratrol on arterial stiffness assessed by CAVI in patients with type 2 diabetes mellitus (T2DM).In this double-blind, randomized, placebo-controlled study, 50 patients with T2DM received supplement of a 100mg resveratrol tablet (total resveratrol: oligo-stilbene 27.97 mg/100 mg/day) or placebo daily for 12 weeks. CAVI was assessed at baseline and the end of study. Body weight (BW), blood pressure (BP), glucose and lipid metabolic parameters, and diacron-reactive oxygen metabolites (d-ROMs; an oxidative stress marker) were also measured.Resveratrol supplementation decreased systolic BP (-5.5 ± 13.0 mmHg), d-ROMs (-25.6 ± 41.8 U.CARR), and CAVI (-0.4 ± 0.7) significantly (P < 0.05) and decreased BW (-0.8 ± 2.1 kg, P = 0.083) and body mass index (-0.5 ± 0.8 kg/m

Topics: Administration, Oral; Ankle Brachial Index; Antioxidants; Atherosclerosis; Diabetes Mellitus, Type 2; Double-Blind Method; Female; Follow-Up Studies; Humans; Male; Middle Aged; Oxidative Stress; Resveratrol; Retrospective Studies; Stilbenes; Treatment Outcome; Vascular Stiffness

The anti-inflammatory effects of the polyphenol resveratrol in patients with type 2 diabetes mellitus (T2DM) are controversial. Its role on pentraxin 3 (PTX3) concentrations, a human acute phase protein, has never been evaluated. Our aim was to determine whether a two-dosage resveratrol supplementation (500 and 40 mg/day) has an impact on PTX3 values in T2DM patients from a double-blind randomized placebo-controlled trial. Variations in total antioxidant status (TAS) were evaluated too.. A total of 192 T2DM patients were randomized to receive resveratrol 500 mg/day (Resv 500 arm), resveratrol 40 mg/day (Resv 40 arm) or placebo for 6 months. At baseline and at the trial end, PTX3 and TAS values were determined.. A dose-dependent increase in PTX3 concentrations of 4.7% (Resv 40 arm) and 26.3% (Resv 500 arm), and 8.0% reduction after placebo were found. Adjusted mean differences of change versus placebo were 0.16 (95% CI 0.01-0.32) and 0.25 (0.09-0.42) in the Resv 40 and Resv 500 arms, respectively. At subgroup analyses, lower diabetes duration, aspirin, alcohol use, younger age, female gender, smoking (Resv 500 arm) and female gender and aspirin use (Resv 40 arm) were associated with higher PTX3 increments. A dose-dependent increment in TAS values in the resveratrol arms (1.4 and 6.4% for Resv 40 and Resv 500, respectively), and a reduction in placebo arm (-8.9%) were observed. Adjusted mean differences of change were 28.5 (95% CI 10.1-46.8) and 44.8 (25.4-64.1) in the Resv 40 and Resv 500 arms, respectively.. Resveratrol supplementation increased PTX3 and TAS levels in a dose-dependent manner in T2DM patients. At present, potential clinical implications of these results remain unclear. CLINICALTRIALS.. NCT02244879.

Topics: Adult; Aged; Antioxidants; C-Reactive Protein; Diabetes Mellitus, Type 2; Dose-Response Relationship, Drug; Double-Blind Method; Drug Administration Schedule; Female; Humans; Male; Middle Aged; Resveratrol; Serum Amyloid P-Component; Stilbenes; Treatment Outcome

Resveratrol has been reported to lower glycemia in rodent models of type 2 diabetes associated with the stimulation of glucagon-like peptide 1 (GLP-1), which is known to slow gastric emptying, stimulate insulin secretion, and suppress glucagon secretion and energy intake.. We evaluated the effects of 5 wk of resveratrol treatment on GLP-1 secretion, gastric emptying, and glycemic control in type 2 diabetes.. Fourteen patients with diet-controlled type-2 diabetes [mean ± SEM glycated hemoglobin (HbA1c): 6.4 ± 0.2% (46.4 ± 2.2 mmol/mol)] received resveratrol (500 mg twice daily) or a placebo over two 5-wk intervention periods with a 5-wk washout period in between in a double-blind, randomized, crossover design. Before and after each intervention period (4 visits), body weight and HbA1c were measured, and patients were evaluated after an overnight fast with a standardized mashed-potato meal labeled with 100 μg (13)C-octanoic acid to measure blood glucose and plasma GLP-1 concentrations and gastric emptying (breath test) over 240 min. Daily energy intake was estimated from 3-d food diaries during the week before each visit.. Fasting and postprandial blood glucose and plasma total GLP-1 as well as gastric emptying were similar at each assessment, and the change in each variable from weeks 0 to 5 did not differ between resveratrol and placebo groups. Similarly, changes in HbA1c, daily energy intake, and body weight after 5 wk did not differ between the 2 treatments.. In patients with diet-controlled type 2 diabetes, 5 wk of twice-daily 500 mg-resveratrol supplementation had no effect on GLP-1 secretion, glycemic control, gastric emptying, body weight, or energy intake. Our observations do not support the use of resveratrol for improving glycemic control. This trial was registered at www.anzctr.org.au as ACTRN12613000717752.

Topics: Aged; Blood Glucose; Body Weight; Diabetes Mellitus, Type 2; Double-Blind Method; Energy Intake; Female; Gastric Emptying; Glucagon-Like Peptide 1; Glycated Hemoglobin; Humans; Hypoglycemic Agents; Insulin; Male; Postprandial Period; Resveratrol; Stilbenes

Progressive microvascular dysfunction in type 2 diabetes mellitus (T2DM) may impair the ability of cerebral vessels to supply blood to brain regions during local metabolic demand, thereby increasing risks of dementia. Having previously demonstrated that resveratrol can enhance vasodilator function in the systemic circulation, we hypothesised that resveratrol could similarly benefit the cerebral circulation. We aimed to determine the most efficacious dose of resveratrol to improve cerebral vasodilator responsiveness (CVR) in T2DM.. In a double-blind, placebo-controlled, balanced crossover intervention, 36 dementia-free, non-insulin dependent T2DM older adults (49-78 years old) consumed single doses of synthetic trans-resveratrol (0, 75, 150, and 300 mg) at weekly intervals. Transcranial Doppler ultrasound was used to assess CVR to a hypercapnic stimulus, both before and 45 min after treatment. CVR, measured bilaterally in the middle cerebral arteries (MCA) and posterior cerebral arteries (PCA), was expressed as the percentage change in mean blood flow velocity from baseline to the peak velocity attained during hypercapnia. Resveratrol consumption increased CVR in the MCA; mean within-individual changes for each dose from placebo were 13.8 ± 3.5% for 75 mg (P = 0.001), 8.9 ± 3.5% for 150 mg (P = 0.016), and 13.7 ± 3.3% for 300 mg (P < 0.001); only the 75 mg dose was efficacious in the PCA (13.2 ± 4.5%, P = 0.016).. Our results provide the first clinical evidence of an acute enhancement of vasodilator responsiveness in cerebral vessels following consumption of resveratrol in this population who are known to have endothelial dysfunction and sub-clinical cognitive impairment. Importantly, maximum improvement was observed with the lowest dose used.. ACTRN12614000891628 (www.anzctr.org.au).

Topics: Aged; Blood Flow Velocity; Cerebrovascular Circulation; Cerebrovascular Disorders; Cognition; Cognition Disorders; Cross-Over Studies; Diabetes Mellitus, Type 2; Diabetic Angiopathies; Dose-Response Relationship, Drug; Double-Blind Method; Female; Humans; Male; Middle Aged; Middle Cerebral Artery; Posterior Cerebral Artery; Resveratrol; Stilbenes; Time Factors; Treatment Outcome; Ultrasonography, Doppler, Transcranial; Vasodilation; Victoria

Poor cerebral perfusion may contribute to cognitive impairment in type 2 diabetes mellitus (T2DM). We conducted a randomized controlled trial to test the hypothesis that resveratrol can enhance cerebral vasodilator function and thereby alleviate the cognitive deficits in T2DM. We have already reported that acute resveratrol consumption improved cerebrovascular responsiveness (CVR) to hypercapnia. We now report the effects of resveratrol on neurovascular coupling capacity (CVR to cognitive stimuli), cognitive performance and correlations with plasma resveratrol concentrations.. Thirty-six T2DM adults aged 40-80 years were randomized to consume single doses of resveratrol (0, 75, 150 and 300 mg) at weekly intervals. Transcranial Doppler ultrasound was used to monitor changes in blood flow velocity (BFV) during a cognitive test battery. The battery consisted of dual-tasking (finger tapping with both Trail Making task and Serial Subtraction 3 task) and a computerized multi-tasking test that required attending to four tasks simultaneously. CVR to cognitive tasks was calculated as the per cent increase in BFV from pre-test basal to peak mean blood flow velocity and also as the area under the curve for BFV.. Compared to placebo, 75 mg resveratrol significantly improved neurovascular coupling capacity, which correlated with plasma total resveratrol levels. Enhanced performance on the multi-tasking test battery was also evident following 75 mg and 300 mg of resveratrol.. a single 75 mg dose of resveratrol was able to improve neurovascular coupling and cognitive performance in T2DM. Evaluation of benefits of chronic resveratrol supplementation is now warranted.

Topics: Adult; Aged; Aged, 80 and over; Attention; Blood Flow Velocity; Cerebral Arteries; Cerebrovascular Circulation; Cognition; Cognition Disorders; Diabetes Mellitus, Type 2; Double-Blind Method; Female; Humans; Male; Middle Aged; Neurovascular Coupling; New South Wales; Resveratrol; Stilbenes; Time Factors; Trail Making Test; Treatment Outcome; Ultrasonography, Doppler, Transcranial; Vasodilation

The polyphenol resveratrol is considered to exert many beneficial actions, such as antioxidant, anti-inflammatory, insulin-sensitizer and anticancer effects. Its benefits in patients with type 2 diabetes mellitus (T2DM) are controversial. Our aims were to determine whether resveratrol supplementation at two different dosages (500 and 40mg/day) for 6 months i) reduced the concentrations of C-reactive-protein (CRP) and ii) ameliorated the metabolic pattern of T2DM patients. In the present double-blind, randomized, placebo-controlled trial, 192 T2DM patients were randomized to receive resveratrol 500mg/day (Resv500arm), resveratrol 40mg/day (Resv40arm) or placebo for 6-months. At baseline and at the trial end, CRP values, anthropometric, metabolic and liver parameters were determined. No serious adverse event occurred. A dose-dependent, though not significant, CRP decrease of 5.6% (Resv40arm) and 15.9% (Resv500arm) was observed vs placebo. We failed to detect significant differences in weight, BMI, waist circumference, and values of arterial blood pressure, fasting glucose, glycated hemoglobin, insulin, C-peptide, free fatty acids, liver transaminases, uric acid, adiponectin, interleukin-6, in both the Resv500 and Resv40 arms vs placebo. Total cholesterol and triglycerides slightly increased in the Resv500arm. Subgroup analyses revealed that lower diabetes duration (in both Resv500 and Resv40arms), and, in the Resv500arm, younger age, aspirin use and being a smoker were associated with a significantly higher CRP reduction vs placebo. The supplementations with 40mg/day or 500mg/day resveratrol did neither reduce CRP concentrations, nor improve the metabolic pattern of T2DM patients.

Topics: Biomarkers; C-Reactive Protein; Diabetes Mellitus, Type 2; Dietary Supplements; Double-Blind Method; Health Status; Humans; Inflammation Mediators; Italy; Resveratrol; Stilbenes; Time Factors; Treatment Outcome

To determine whether resveratrol supplementation can improve insulin sensitivity and promote overall metabolic health on top of standard diabetes care.. Seventeen subjects with well-controlled type 2 diabetes (T2D) were treated with placebo and 150 mg/day resveratrol (resVida) in a randomized double-blind crossover study for 30 days. The main outcome measure was insulin sensitivity by the hyperinsulinemic-euglycemic clamp technique.. Hepatic and peripheral insulin sensitivity were not affected by resveratrol treatment. Intrahepatic lipid content also remained unaffected by resveratrol; however, the change in intrahepatic lipid content correlated negatively with plasma resveratrol levels (R = -0.68, P = 0.03). Intramyocellular lipid content increased in type 2 muscle fibers (P = 0.03), and systolic blood pressure tended to decrease (P = 0.09) upon resveratrol treatment. In addition, resveratrol significantly improved ex vivo mitochondrial function (state 3 and state U respiration upon malate with octanoyl-carnitine, P < 0.005). Intriguingly, a correlation was found between plasma levels of a metabolite of resveratrol (dihydroresveratrol) and the metformin dose used by the patients (R = 0.66, P = 0.005), suggesting an interaction between metformin and resveratrol. It could be speculated that the lack of a resveratrol-induced insulin-sensitizing effect is caused by this interaction.. Resveratrol supplementation does not improve hepatic or peripheral insulin sensitivity. Our results question the generalized value of resveratrol as an add-on therapy in the treatment of T2D and emphasize the need to perform studies in drug-naive patients with T2D or subjects with prediabetes.

Topics: Adult; Aged; Blood Glucose; Cross-Over Studies; Diabetes Mellitus, Type 2; Double-Blind Method; Drug Therapy, Combination; Glucose Clamp Technique; Humans; Hypoglycemic Agents; Insulin; Insulin Resistance; Male; Metformin; Middle Aged; Resveratrol; Stilbenes

The primary aims of the study were to examine the effect of resveratrol on skeletal muscle SIRT1 expression and energy expenditure in subjects with Type 2 diabetes mellitus (T2DM).. Animal and in vivo studies indicate that resveratrol increases SIRT1 expression that stimulates PGC1α activity. Subsequent upregulation of AMPK and GLUT4 expression are associated with improved insulin sensitivity in peripheral tissues.. Ten subjects with T2DM were randomized in a double-blind fashion to receive 3g resveratrol or placebo daily for 12 weeks. Secondary outcomes include measures of AMPK, p-AMPK and GLUT4 expression levels, energy expenditure, physical activity levels, distribution of abdominal adipose tissue and skeletal muscle fiber type composition, body weight, HbA1c, plasma lipid subfraction, adiponectin levels, and insulin sensitivity.. There was a significant increase in both SIRT1 expression (2.01 vs. 0.86 arbitrary units [AU], p = .016) and p-AMPK to AMPK expression ratio (2.04 vs. 0.79 AU, p = .032) in the resveratrol group compared with the placebo group. Although the percentage of absolute change (8.6 vs. -13.9%, p = .033) and percentage of predicted resting metabolic rate (RMR; 7.8 vs. -13.9%, p = .013) were increased following resveratrol, there was a significant reduction in average daily activity (-38 vs. 43.2%, p = .028) and step counts (-39.5 vs. 11.8%, p = .047) when compared with placebo.. In patients with T2DM, treatment with resveratrol regulates energy expenditure through increased skeletal muscle SIRT1 and AMPK expression. These findings indicate that resveratrol may have beneficial exercise-mimetic effects in patients with T2DM.

Topics: AMP-Activated Protein Kinases; Basal Metabolism; Diabetes Mellitus, Type 2; Double-Blind Method; Energy Metabolism; Exercise; Glucose Transporter Type 4; Humans; Insulin Resistance; Male; Middle Aged; Muscle, Skeletal; Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; Physical Exertion; Plant Extracts; Rest; Resveratrol; Sirtuin 1; Stilbenes; Transcription Factors; Vitis

Numerous studies have shown that resveratrol (RES) exerts anti-inflammatory effects but human trials evidencing these effects in vivo are limited. Furthermore, the molecular mechanisms triggered in humans following the oral intake of RES are not yet understood. Therefore, the purpose of this study was to investigate the molecular changes in peripheral blood mononuclear cells (PBMCs) associated to the one-year daily intake of a RES enriched (8 mg) grape extract (GE-RES) in hypertensive male patients with type 2 diabetes mellitus (T2DM). We used microarrays and RT-PCR to analyze expression changes in genes and microRNAs (miRs) involved in the inflammatory response modulated by the consumption of GE-RES in comparison to a placebo and GE lacking RES. We also examined the changes in several serobiochemical variables, inflammatory and fibrinolytic markers. Our results showed that supplementation with GE or GE-RES did not affect body weight, blood pressure, glucose, HbA1c or lipids, beyond the values regulated by gold standard medication in these patients. We did not find either any significant change on serum inflammatory markers except for a significant reduction of ALP and IL-6 levels. The expression of the pro-inflammatory cytokines CCL3, IL-1β and TNF-α was significantly reduced and that of the transcriptional repressor LRRFIP-1 increased in PBMCs from patients taking the GE-RES extract. Also, a group of miRs involved in the regulation of the inflammatory response: miR-21, miR-181b, miR-663, miR-30c2, miR-155 and miR-34a were found to be highly correlated and altered in the group consuming the GE-RES for 12 months. Our results provide preliminary evidence that long-term supplementation with a grape extract containing RES downregulates the expression of key pro-inflammatory cytokines with the involvement of inflammation-related miRs in circulating immune cells of T2DM hypertensive medicated patients and support a beneficial immunomodulatory effect in these patients.

Topics: Aged; Anti-Inflammatory Agents, Non-Steroidal; Coronary Artery Disease; Cytokines; Diabetes Mellitus, Type 2; Dietary Supplements; Gene Expression Regulation; Humans; Hypertension; Inflammation; Leukocytes, Mononuclear; Male; MicroRNAs; Middle Aged; Models, Molecular; Plant Extracts; Resveratrol; Stilbenes; Transcriptome; Vitis

Resveratrol is a naturally occurring polyphenolic compound. Numerous animal studies have been reported on its wide-ranging beneficial effects in the biological system including diabetes mellitus (DM). We hypothesized, therefore, that oral supplementation of resveratrol would improve the glycemic control and the associated risk factors in patients with type 2 diabetes mellitus (T2DM). The present clinical study was therefore carried out to test the hypothesis. Sixty-two patients with T2DM were enrolled from Government Headquarters Hospital, Ootacamund, India, in a prospective, open-label, randomized, controlled trial. Patients were randomized into control and intervention groups. The control group received only oral hypoglycemic agents, whereas the intervention group received resveratrol (250 mg/d) along with their oral hypoglycemic agents for a period of 3 months. Hemoglobin A(1c), lipid profile, urea nitrogen, creatinine, and protein were measured at the baseline and at the end of 3 months. The results reveal that supplementation of resveratrol for 3 months significantly improves the mean hemoglobin A(1c) (means ± SD, 9.99 ± 1.50 vs 9.65 ± 1.54; P < .05), systolic blood pressure (mean ± SD, 139.71 ± 16.10 vs 127.92 ± 15.37; P < .05), total cholesterol (mean ± SD, 4.70 ± 0.90 vs 4.33 ± 0.76; P < .05), and total protein (mean ± SD, 75.6 ± 4.6 vs 72.3 ± 6.2; P < .05) in T2DM. No significant changes in body weight and high-density lipoprotein and low-density lipoprotein cholesterols were observed. Oral supplementation of resveratrol is thus found to be effective in improving glycemic control and may possibly provide a potential adjuvant for the treatment and management of diabetes.

Topics: Administration, Oral; Aged; Blood Glucose; Body Mass Index; Cholesterol, LDL; Creatinine; Diabetes Mellitus, Type 2; Dietary Supplements; Female; Glycated Hemoglobin; Humans; Hypoglycemic Agents; India; Male; Middle Aged; Nitrogen; Prospective Studies; Resveratrol; Risk Factors; Stilbenes

Although resveratrol has widely been studied for its potential health benefits, little is known about its metabolic effects in humans. Our aims were to determine whether the polyphenol resveratrol improves insulin sensitivity in type 2 diabetic patients and to gain some insight into the mechanism of its action. After an initial general examination (including blood chemistry), nineteen patients enrolled in the 4-week-long double-blind study were randomly assigned into two groups: a resveratrol group receiving oral 2 × 5 mg resveratrol and a control group receiving placebo. Before and after the second and fourth weeks of the trial, insulin resistance/sensitivity, creatinine-normalised ortho-tyrosine level in urine samples (as a measure of oxidative stress), incretin levels and phosphorylated protein kinase B (pAkt):protein kinase B (Akt) ratio in platelets were assessed and statistically analysed. After the fourth week, resveratrol significantly decreased insulin resistance (homeostasis model of assessment for insulin resistance) and urinary ortho-tyrosine excretion, while it increased the pAkt:Akt ratio in platelets. On the other hand, it had no effect on parameters that relate to β-cell function (i.e. homeostasis model of assessment of β-cell function). The present study shows for the first time that resveratrol improves insulin sensitivity in humans, which might be due to a resveratrol-induced decrease in oxidative stress that leads to a more efficient insulin signalling via the Akt pathway.

Topics: Adult; Blood Platelets; Diabetes Mellitus, Type 2; Double-Blind Method; Humans; Insulin Resistance; Male; Middle Aged; Oxidative Stress; Phytotherapy; Plant Extracts; Proto-Oncogene Proteins c-akt; Resveratrol; Signal Transduction; Stilbenes; Tyrosine

Chronically elevated free fatty acid levels can adversely affect pancreatic β-cells, leading to insulin resistance and eventually type 2 diabetes mellitus (T2DM). Polydatin (PD) from Polygonum cuspidatum has been shown to regulate blood lipid content and lower cholesterol levels. However, there have been no reports on the potential therapeutic effects and actions of PD on lipotoxicity in β-cells.. This study aimed to investigate the protective effects of PD on palmitate (PA)-treated INS-1 insulinoma cells and diabetic mice.. Cells were incubated with PA and varying concentrations of PD for 24 h. Viability assays, morphological observations, flow cytometric analysis, western blotting, and reverse transcription-quantitative polymerase chain reaction were used to assess the effects of PD on PA-induced lipotoxicity. Western blotting was used to measure the endoplasmic reticulum stress (ERS) and the levels of autophagy-related factors after incubation with inducers and inhibitors of ERS and autophagy. Diabetic mice were treated with intragastric PD for 6 weeks followed by the measurement of their physiological and blood lipid indices and assessment of the results of histological and immunofluorescence analyses.. Treatment with PD after PA exposure enhanced insulin secretion and the expression of diabetes-associated genes. PD promoted β-cell function by reducing the levels of proteins associated with ERS and autophagy while also attenuating ERS triggered by tunicamycin. PD also reduced tunicamycin-induced autophagy, indicating that it regulated ERS-mediated autophagy and reduced PA-induced cellular dysfunction. In addition, treatment of db/db mice with PD substantially reduced body weight gain, alleviated dyslipidemia, improved β-cell function, and reduced insulin resistance.. These results suggest that PD protects β-cells from lipotoxicity-induced dysfunction and apoptosis by inhibiting ERS and preventing excessive autophagy. Our study provides a new basis for exploring the potential of PD against β-cell lipotoxicity and T2DM.

Topics: Animals; Apoptosis; Autophagy; Cholesterol; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Endoplasmic Reticulum Stress; Fatty Acids, Nonesterified; Glucosides; Insulin Resistance; Insulin-Secreting Cells; Mice; Palmitates; Stilbenes; Tunicamycin

Polydatin (PD) has many pharmacological activities; however, its bioavailability is still a critical cornerstone issue. The present investigation aimed to develop a novel oral formula of polydatin-loaded chitosan nanoparticles (PD-CSNPs) to improve PD therapeutic potential against type 2 diabetes. The interaction mechanism between PD and CSNPs was studied via Monte Carlo and molecular dynamics simulations. The formula was prepared and characterized by FTIR, XRD, TEM, and dynamic light scattering. The release profile of PD was studied in vitro, as well as the cytotoxicity effect versus Vero cell line and antidiabetic activity in type 2 diabetic rats were investigated. The practical results verified the formation of PD-CSNPs with entrapment efficiency of about 96.74 ± 0.39%, size average 144.25 ± 3.37 nm, and the prolonged release pattern was less than 20% after 12 hrs. The cytotoxicity study confirmed the safety of the formula at low and high doses. Moreover, the in vivo study revealed that PD-CSNPs exhibited highly significant antidiabetic efficacy in diabetic rats compared to free PD. To conclude, the current investigation proved that CSNPs are promising nanocarriers for nontoxic and effective PD delivery against type 2 diabetes.

Topics: Animals; Biomarkers; Body Weight; Chitosan; Chlorocebus aethiops; Diabetes Mellitus, Type 2; Drug Carriers; Drug Liberation; Glucosides; Hypoglycemic Agents; Male; Molecular Conformation; Molecular Dynamics Simulation; Nanoparticles; Particle Size; Rats; Rats, Wistar; Safety; Stilbenes; Vero Cells

Isorhapontigenin is a natural bioactive stilbene isolated from various plants and fruits. It has been reported to exhibit several physiological activities including anticancer and anti-inflammation activity in vitro and in experimental animal models. This study aimed to investigate whether isorhapontigenin exerts antidiabetic effects in vivo. To this end, diabetic

Topics: 3T3-L1 Cells; Adipocytes; Animals; Blood Glucose; Cell Differentiation; Diabetes Mellitus, Type 2; Humans; Hypoglycemic Agents; Insulin Resistance; Male; Mice; PPAR gamma; Stilbenes

Topics: Animals; Chemical and Drug Induced Liver Injury; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Dyslipidemias; Glycemic Load; Male; Protective Agents; Rats; Rats, Sprague-Dawley; Specific Pathogen-Free Organisms; Stilbenes

Diabetic cardiomyopathy is a main cause of the increased morbidity in diabetic patients, no effective treatment is available so far. Polydatin, a resveratrol glucoside isolated from the Polygonum cuspidatum, was found by our and others have antioxidant and cardioprotective activities. Therapeutic effects of polydatin on diabetic cardiomyopathy and the possible mechanisms remains unclear. This study aimed to investigate the cardioprotective effects and underlying mechanisms of polydatin on myocardial injury induced by hyperglycemia.. Diabetes in rats was made by high-fat diet combined with multiple low doses of streptozotocin, and then treated with polydatin (100 mg·kg-1·day-1, by gavage) for 8 weeks. Cardiac function was examined by echocardiography. Myocardial tissue and blood samples were collected for histology, protein and metabolic characteristics analysis. In cultured H9c2 cells with 30 mM of glucose, the direct effects of polydatin on myocyte injury were also observed.. In diabetic rats, polydatin administration significantly improved myocardial dysfunction and attenuated histological abnormalities, as evidenced by elevating left ventricular shortening fraction and ejection fraction, as well as reducing cardiac hypertrophy and interstitial fibrosis. In cultured H9c2 cells, pretreatment of polydatin dose-dependently inhibited high glucose-induced cardiomyocyte injury. Further observation evidenced that polydatin suppressed the increase in the reactive oxygen species levels, NADPH oxidase activity and inflammatory cytokines production induced by hyperglycemia in vivo and in vitro. Polydatin also prevented the increase expression of NOX4, NOX2 and NF-κB in the high glucose -stimulated H9c2 cells and diabetic hearts.. Our results demonstrate that the cardioprotective effect of polydatin against hyperglycemia-induced myocardial injury is mediated by inhibition of NADPH oxidase and NF-κB activity. The findings may provide a novel understanding the mechanisms of the polydatin to be a potential treatment of diabetic cardiomyopathy.

Topics: Animals; Cardiomyopathies; Cell Line; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Drug Evaluation, Preclinical; Drugs, Chinese Herbal; Fallopia japonica; Glucosides; Heart; Male; Myocardium; NADPH Oxidases; NF-kappa B; Oxidative Stress; Rats, Sprague-Dawley; Stilbenes

In an effort to identify agents from natural products that inhibit protein tyrosine phosphatase 1B (PTP1B), 5 new prenylated stilbenes, (±)-styrastilbene A (1: ), styrastilbene B (2: ), and (±)-styrastilbenes C - E (3, 4: , and 7: ), along with 4 known structurally related compounds (5, 6, 8: , and 9: ), were isolated from the roots of

Topics: Artocarpus; Diabetes Mellitus, Type 2; Enzyme Inhibitors; Molecular Docking Simulation; Molecular Structure; Plant Roots; Prenylation; Protein Tyrosine Phosphatase, Non-Receptor Type 1; Stilbenes

Pterostilbene, a bioactive component of blueberries and grapes, shows structural similarity to resveratrol, and exhibits antioxidant, anti-inflammatory, anti-cancer, hypoglycemic, and cholesterol lowering effects. Recent evidence indicates that pterostilbene is an agonist of the nuclear receptor, peroxisome proliferator-activated receptor-alpha (PPAR-α). Since PPAR-α agonists induce peroxisomal proliferation and fatty acid oxidation, we examined gene expression of acyl CoA oxidase (ACO) and carnitine palmitoyl transferase-1 (CPT-1). Pterostilbene treatment, at concentrations that demonstrated over 75% cell viability (20 μM, 50 μM), significantly increased gene expression of ACO, CPT-1, and PPAR-α. Pterostilbene treatment (50 μM) also demonstrated potent activation of AMP-activated kinase (AMPK), compared to AICAR (0.5 mM) or metformin (2 mM), consistent with upregulation in fatty acid oxidation gene expression. Since AMPK activators mimic the actions of insulin by repressing hepatic gluconeogenesis, we examined pterostilbene's effects on hepatic gluconeogenic gene expression. Pterostilbene treatment significantly repressed dexamethasone-induced phosphoenol pyruvate carboxykinase (PEPCK) and glucose6-phosphatase (G6Pase) gene expression, and decreased glucose production in H4IIE cells. Taken together, our studies demonstrate that pterostilbene, a natural compound and PPAR-α agonist, modulate several AMPK-dependent metabolic functions. The results of the present study suggest that pterostilbene may have beneficial effects in the prevention and management of type 2 diabetes and related disorders. In this study, we found that pterostilbene activated AMP-activated kinase (AMPK) and increased the expression of fatty acid oxidation genes, including acyl CoA oxidase and carnitine palmitoyl transferase-1.

Topics: AMP-Activated Protein Kinases; Animals; Cell Line; Diabetes Mellitus, Type 2; Enzyme Activators; Fatty Acids; Gene Expression Regulation; Gluconeogenesis; Glucose; Hypoglycemic Agents; Liver; Oxidation-Reduction; PPAR alpha; Rats; Stilbenes

Type 2 diabetes mellitus (T2DM) is a metabolic disorder that is associated with variable degrees of glucose intolerance, impaired insulin secretion, insulin resistance and increased hepatic glucose production. The aim of present study was to investigate the therapeutic potentials of resveratrol (RSV) alone and/or in combination with vitamin-E (Vit-E) against hyperglycemia-induced modulations using experimentally alloxan-induced diabetic animal model. Alloxan was used to induce diabetes mellitus in white albino rats and metformin (MF) was used as standard anti-diabetic drug to compare the therapeutic potentials of RSV (alone and/or with Vit-E) by estimating the effect of treatment on glycemia, insulin resistance, liver and kidney function biomarkers, anti-oxidant status, and serum levels of calcium and magnesium. The results of present study indicate the RSV (P < 0.001) alone and/or in combination with Vit-E (P < 0.001) exhibited a highly significant therapeutic potentials by ameliorating the glycemia-induced modulations. Moreover, we also found that RSV in combination with Vit-E also exhibited a better therapeutic effects when compared with that of MF (P < 0.001) and Vit-E (P < 0.05), respectively. Hence, we conclude that RSV alone and/or in combination with Vit-E exhibit its significant therapeutic potentials against hyperglycemia-induced modulations in experimental diabetic animal model and may be one of the most exciting prospect for future treatment of T2DM.

Topics: Animals; Antioxidants; Blood Glucose; Calcium; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Drug Therapy, Combination; Female; Hyperglycemia; Insulin; Insulin Resistance; Magnesium; Male; Metformin; Rats; Resveratrol; Stilbenes; Vitamin E

Topics: Antioxidants; Biomarkers; Diabetes Mellitus, Type 2; Humans; Oxidative Stress; Resveratrol; Stilbenes

Topics: Biomarkers; Diabetes Mellitus, Type 2; Dietary Supplements; Double-Blind Method; Humans; Oxidative Stress; Resveratrol; Stilbenes

The present study investigated the effects of cajanonic acid A (CAA), extracted from the leaves of Cajanus cajan (L.) Millsp with a purity of 98.22%, on the regulatory mechanisms of glucose and lipid metabolism. HepG2 cells transfected with a protein‑tyrosine phosphatase 1B (PTP1B) overexpression plasmid were established. The cells, induced with insulin resistance by dexamethasone (Dex) treatment, together with type 2 diabetes mellitus (T2DM) model rats and ob/ob mice, were used in the present study. The effects of CAA treatment on the differentiation of 3T3‑L1 adipocytes were determined using Oil Red O. The expression levels of insulin signaling factors were detected via reverse transcription‑quantitative polymerase chain reaction and western blot analyses. The results revealed that the overexpression of PTP1B contributed to insulin resistance, which was reversed by CAA treatment via inhibiting the activity of PTP1B and by regulating the expression of associated insulin signaling factors. The treatment of cell lines with Dex led to increased expression of PTP1B but decreased glucose consumption, and decreased tyrosine phosphorylation of insulin receptor, insulin receptor substrate 1, and phosphoinositide 3‑kinase. Treatment with CAA not only reduced the fasting blood glucose levels and protected organs from damage, but also reduced the serum fasting levels of total cholesterol, triglycerides and low‑density lipoprotein cholesterol in the T2DM rats. CAA treatment also inhibited adipocyte differentiation and decreased the mRNA levels of various adipogenic genes. Furthermore, CAA treatment restored the transduction of insulin signaling by regulating the expression of PTP1B and associated insulin signaling factors. Treatment with CAA also reduced the problems associated with hyperglycemia and hyperlipidemia. In conclusion, CAA may be used to cure T2DM via restoring insulin resistance and preventing obesity.

Topics: 3T3-L1 Cells; Animals; Cajanus; Diabetes Mellitus, Type 2; Glucose; Hep G2 Cells; Humans; Hypoglycemic Agents; Insulin Resistance; Lipid Metabolism; Male; Mice; Protein Tyrosine Phosphatase, Non-Receptor Type 1; Rats, Sprague-Dawley; Stilbenes

Polydatin (PD), a resveratrol glycoside, has been shown to protect renal function in diabetic nephropathy (DN), but the underlying molecular mechanism remains unclear. This study demonstrates that PD stabilize the mitochondrial morphology and attenuate mitochondrial malfunction in both KKAy mice and in hyperglycemia (HG)-induced MPC5 cells. We use Western blot analysis to demonstrate that PD reversed podocyte apoptosis induced by HG via suppressing dynamin-related protein 1 (Drp1). This effect may depend on the ability of PD to inhibit the generation of cellular reactive oxygen species (ROS). In conclusion, we demonstrate that PD may be therapeutically useful in DN, and that, podocyte apoptosis induced by HG can be reversed by PD through suppressing Drp1 expression.

Topics: Animals; Apoptosis; Blood Glucose; Cell Line; Cytoprotection; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Disease Models, Animal; Down-Regulation; Dynamins; Glucosides; Mice, Inbred C57BL; Mitochondria; Mitochondrial Dynamics; Podocytes; Reactive Oxygen Species; RNA Interference; Signal Transduction; Stilbenes; Transfection

The effect of diabetes on the pharmacokinetics, bioavailability and brain distribution of grape polyphenols and select metabolites was studied in the Zucker diabetic fatty (ZDF) rat model.. (ZDF) rats and their lean controls (LN) were dosed with a Standardized Grape Polyphenol (SGP) Mixture consisting of grape seed extract, Concord grape juice and resveratrol (RES) by oral gavage for 10 days. An 8-h pharmacokinetic study was performed. After 24 h, a second dose of SGP was administered and 1 h later animals were sacrificed and brain tissue was harvested. Plasma, urine, and brain tissue were analyzed for grape polyphenols. ZDF rats exhibited significantly diminished C. Diabetes may alter the overall bioavailability of some polyphenols in plasma and brain in part due to higher urinary clearance.

Topics: Animals; Anthocyanins; Biological Availability; Blood Glucose; Brain; Catechin; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Flavonoids; Grape Seed Extract; Male; Polyphenols; Quercetin; Rats; Rats, Zucker; Resveratrol; Stilbenes; Tandem Mass Spectrometry; Vitis

The present investigation was designed to explore the effectiveness of pterostilbene (PT) on insulin resistance, metabolic syndrome and oxidative stress in fructose-fed insulin resistant rats.. Age-matched, male Sprague-Dawley rats (330±30g body weight) were allocated into five groups (n=10). Control (C) group received 65% cornstarch, and the diabetic (D) group received 65% fructose for eight weeks. The third group (D+PT20) received 65% fructose and PT 20mg/kg/day for eight weeks. The fourth group (D+PT40) received 65% fructose and PT 40mg/kg/day for eight weeks. The fifth group (D+M) received 65% fructose and metformin (M) 100mg/kg/day for eight weeks. PT was dissolved in 10% β-cyclodextrin and given orally to rats. Several biochemical parameters were determined to assess the PT efficacy against insulin resistance, metabolic complications, and hepatic oxidative stress.. Significantly high HOMA-IR (p<0.001) values in D group compared to C group indicate the presence of insulin resistance. Significantly high levels of TBARS (p<0.001) and decreased levels of SOD (p<0.001) and GSH (p<0.001) in hepatic tissues of D group indicate oxidative stress associated with insulin resistance. Pterostilbene treatment to fructose-fed diabetic rats significantly decreased HOMA-IR (p<0.001) values. Furthermore, PT treatment significantly decreased hepatic TBARS (p<0.001) and increased SOD (p<0.001) and GSH (p<0.001) levels in fructose-fed diabetic rats.. Current study reveals that PT is successful in ameliorating glycemic control, insulin sensitivity while diminishing metabolic disturbances and hepatic oxidative stress in a fructose-induced T2DM rat model.

Topics: Animals; beta-Cyclodextrins; Blood Glucose; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Fructose; Insulin Resistance; Male; Metabolic Syndrome; Metformin; Oxidative Stress; Rats; Rats, Sprague-Dawley; Stilbenes; Superoxide Dismutase; Thiobarbituric Acid Reactive Substances

Topics: Diabetes Mellitus, Type 2; Humans; Resveratrol; Stilbenes; Vitamin D

Topics: Diabetes Mellitus, Type 2; Humans; Resveratrol; Stilbenes; Vitamin D

Insulin resistance is a characteristic finding in hyperglycaemia and type 2 diabetes. SIRT1 is a NAD

Topics: AMP-Activated Protein Kinases; Animals; Biological Transport; Carbohydrate Metabolism; Cell Culture Techniques; Diabetes Mellitus, Type 2; Disease Models, Animal; Energy Metabolism; Glucose; Glucose Transporter Type 4; Heterocyclic Compounds, 3-Ring; Insulin; Insulin Resistance; Lactones; Muscle, Skeletal; Myoblasts; Organelle Biogenesis; Phytochemicals; Rats; Signal Transduction; Sirtuin 1; Stilbenes

Diabetes is a common metabolic disorder characterized by elevated blood glucose level. Trace element homeostasis causes disturbances in diabetes due to hyperglycemia. Superoxide dismutase (SOD), an antioxidant enzyme, contains zinc and copper ions as its cofactors. Defects in SOD level and activity have been observed in diabetes. Resveratrol (RSV) has displayed hypoglycemic effects and is proven to improve oxidative stress. The aim of the present study was to examine the possible effects of RSV on blood glucose level, serum copper and zinc levels, SOD, and a number of other oxidative markers in type 2 diabetic rats. Diabetes was induced in male Wistar rats with administration of streptozotocin and nicotine amide. The studied groups containing six animals per group were as follows: group 1 normal control group; group 2 diabetic control group; groups 3, 4, and 5 diabetic rats that received 1, 5, and 10 mg/kg body weight of RSV, respectively for 30 days. Serum glucose, copper, zinc, SOD activity, total oxidant status (TOS) as well as thiol groups were all measured. Blood glucose in RSV treated groups significantly decreased. Similarly, copper significantly decreased in diabetic groups treated with RSV. Treatment with 10 mg/kg RSV resulted in significantly increased serum zinc. Furthermore, Cu/Zn ratio was observed to decrease in treated groups compared with untreated diabetic control group. RSV treated groups revealed an increased level of SOD activity as well as improved oxidative status. In summary, the results showed that RSV has potential hypoglycemic effect, attenuates trace element homeostasis, and consequently increases SOD activity level.

Topics: Administration, Oral; Animals; Copper; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Dose-Response Relationship, Drug; Homeostasis; Male; Oxidative Stress; Rats; Rats, Wistar; Resveratrol; Stilbenes; Superoxide Dismutase; Zinc

Functional foods can be used alone or in combination with existing therapies in preventing and treating type 2 diabetes (T2D). Trans-2,3,5,4'-tetrahydroxystilbene 2-O-β-glucopyranoside (trans-THSG), a dominant bioactive compound from Polygonum multiflorum (PM)-a popular medicinal food in Asia, has attracted increasing research interests due to its strong antioxidant activity. The content of naturally occurring cis-THSG (cis-2,3,5,4'-tetrahydroxystilbene 2-O-β-glucopyranoside) was very low in PM root, but was prepared in this study by mimicking the traditional process of PM. The anti-diabetic effects of trans- and cis-THSG were evaluated in T2D to search for more efficacious food ingredient(s).. Trans-THSG was chromatographically purified from PM roots and cis-THSG was prepared with our innovative process via exposure of trans-THSG to UV-light. The anti-diabetic effects of both THSGs were tested with HFD-induced male CF-1 diabetic mice. Cis-THSG was found more effective than trans-THSG in hypoglycemic effect and in ameliorating glucose intolerance and insulin resistance. In HepG2 cells, cis-THSG also demonstrated more potent activity than trans-THSG in suppressing transcription of phosphoenopyruvate carboxykinase (PEPCK).. Cis-THSG can be an enriched bioactive ingredient in PM roots from post-processing and is significantly more effective against hyperglycemia than trans-THSG. One of the effective pathways was through inhibition of PEPCK.

Topics: Animals; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Diet, High-Fat; Enzyme Inhibitors; Fallopia multiflora; Glucosides; Hep G2 Cells; Humans; Hypoglycemic Agents; Insulin Resistance; Male; Phosphoenolpyruvate Carboxykinase (ATP); Stilbenes

Incidence of diabetes mellitus is dramatically growing in the world. Oxidative stress, advanced glycation end products (AGEs) and receptor for AGE (RAGE) play key role in the pathogenesis of diabetes. Little is known about resveratrol effects on the liver. We hypothesize that resveratrol may exert a hepatoprotective effect in diabetic rats. Male rats with diabetes were treated with or without resveratrol at 1, 5 and 10 mg/kg body weight for 30 days. Total AGEs and malondialdehyde (MDA) levels in liver tissues were determined by spectrofluorimetric methods. Total antioxidant capacity and total oxidant contents in the liver and glucose in plasma were measured by a colorimetric assay. Expression of RAGE was assayed in liver of all animals using quantitative polymerase chain reaction. In liver tissue extract of resveratrol-treated rats with diabetes, MDA levels, total oxidant, plasma glucose and expression of RAGE were significantly reduced compared to the untreated group. Moreover, total antioxidant levels were significantly increased in treated rats. There was no significant difference in AGE contents among all groups. These results revealed that resveratrol had beneficial effects on the liver by extenuating oxidative stress and down regulation of RAGE expression.

Topics: Animals; Antioxidants; Blood Glucose; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Lipid Peroxidation; Liver; Male; Malondialdehyde; Oxidative Stress; Rats; Rats, Wistar; Receptor for Advanced Glycation End Products; Resveratrol; Stilbenes

Abnormalities in lipid and glucose metabolism are constantly observed in type 2 diabetes. However, these abnormalities can be ameliorated by polydatin. Considering the important role of proprotein convertase subtilisin/kexin type 9 (PCSK9) in metabolic diseases, we explore the possible mechanism of polydatin on lipid and glucose metabolism through its effects on PCSK9.. An insulin-resistant HepG2 cell model induced by palmitic acid (PA) and a db/db mice model were used to clarify the role of polydatin on lipid and glucose metabolism.. In insulin-resistant HepG2 cells, polydatin upregulated the protein levels of LDLR and GCK but repressed PCSK9 protein expression, besides, polydatin also inhibited the combination between PCSK9 and LDLR. Knockdown and overexpression experiments indicated that polydatin regulated LDLR and GCK expressions through PCSK9. In the db/db mice model, we found that polydatin markedly enhanced GCK and LDLR protein levels, and inhibited PCSK9 expression in the liver. Molecular docking assay was further performed to analyze the possible binding mode between polydatin and the PCSK9 crystal structure (PDB code: 2p4e), which indicated that steady hydrogen bonds formed between polydatin and PCSK9.. Our study indicates that polydatin ameliorates lipid and glucose metabolism in type 2 diabetes mellitus by downregulating PCSK9.

Topics: Animals; Biomarkers; Blood Glucose; Diabetes Mellitus, Type 2; Disease Models, Animal; Down-Regulation; Drugs, Chinese Herbal; Female; Germinal Center Kinases; Glucosides; Hep G2 Cells; Hepatocytes; Humans; Hydrogen Bonding; Hypoglycemic Agents; Insulin Resistance; Lipid Metabolism; Lipids; Liver; Mice; Mice, Inbred C57BL; Molecular Docking Simulation; Palmitic Acid; Proprotein Convertase 9; Proprotein Convertases; Protein Binding; Protein Conformation; Protein Serine-Threonine Kinases; Receptors, LDL; RNA Interference; Serine Endopeptidases; Stilbenes; Time Factors; Transfection

Type 2 diabetic nephropathy (DN) is a serious end-stage kidney disease worldwide. Multiple studies demonstrate that resveratrol (RSV) has a beneficial effect on DN. However, whether RSV-induced improvement in kidney function in diabetes is due to the regulation of autophagy remains unclear. Here, we investigated the mechanisms underlying RSV-mediated protection against DN in diabetic rats, with a special focus on the role of NAD-dependent deacetylase sirtuin 1 (Sirt1) in regulating autophagy. We found that long-term RSV treatment in rats promoted Sirt1 expression and improved related metabolic levels in the diabetic kidney. Our study showed that, in cultured NRK-52E cells, Sirt1 knockdown inhibited the autophagy levels of proteins Atg7, Atg5, and LC3 and impaired the RSV amelioration of dysfunctional autophagy under hypoxic condition. Furthermore, exposed to 1% O2 over time induced autophagy dysfunction and apoptosis in NRK-52E cells, which could be improved by RSV treatment. Our data highlight the role of the Sirt1-mediated pathway in the effects of RSV on autophagy in vivo and in vitro, suggesting RSV could be a potential new therapy for type 2 DN.

Topics: Animals; Antioxidants; Autophagy; Blotting, Western; Cell Hypoxia; Cell Line; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Enzyme-Linked Immunosorbent Assay; Gene Knockdown Techniques; Male; Rats; Rats, Sprague-Dawley; Resveratrol; Reverse Transcriptase Polymerase Chain Reaction; Sirtuin 1; Stilbenes

Downregulation of adiponectin (APN) multimerization is significantly correlated with the aggravation of myocardial ischemia/reperfusion (MI/R) injury in type 2 diabetes mellitus (T2DM). Resveratrol (RSV) upregulates APN multimerization in adipocytes, but whether RSV improves endogenous APN multimerization and thus attenuates MI/R injury in T2DM mice has never been investigated. T2DM mice were treated with 10 mg/kg RSV daily for 3 weeks, followed by 30 minutes of myocardial ischemia and 3 hours or 24 hours of reperfusion. RSV administration alleviated MI/R injury in diabetic mice, as evidenced by reduced infarct size, cardiomyocyte apoptosis, and caspase-3 activity, and improved cardiac function. Moreover, RSV reversed the downregulated APN levels and multimerization both in plasma and adipose tissue, accompanied by increased disulfide bond A oxidoreductase-like protein (DsbA-L) expression in T2DM mice. Conversely, serving as a key downstream molecule of APN in ameliorating MI/R injury, inhibition of AMP-activated protein kinase (AMPK) significantly attenuated the cardioprotective effects of RSV. In conclusion, long-term administration of RSV upregulates adiponectin levels and multimerization in T2DM mice, consequently attenuating MI/R injury partially through APN-AMPK signaling.

Topics: Adiponectin; Animals; Cardiotonic Agents; Diabetes Mellitus, Type 2; Male; Mice; Mice, Inbred C57BL; Myocardial Reperfusion Injury; Protein Multimerization; Random Allocation; Resveratrol; Stilbenes; Up-Regulation

Hyperglycaemia in diabetes is either caused by reduced availability of insulin (type 1 diabetes, T1D) or insulin resistance to the cells (type 2 diabetes, T2D). In recent years, the prevalence of T2D has increased to an alarming proportion, encompassing 95 percent of the total diabetic burden, probably due to economy-driven changes in lifestyle. Recent epidemiological studies show comorbid depression, anxiety and related mental illness. To explore the molecular mechanisms underlying this comorbid conditions, we used Sprague-Dawley rats on high-fructose diet for 8 weeks to induce prediabetic condition. Rats with this metabolic syndrome also showed hyper-anxiety when they were subjected to anxiety-related behavioural assays. Rats were administered with resveratrol, an activator of sirtuins, and metformin, a standard antidiabetic drug, simultaneously with fructose. We observed that resveratrol was more effective in protecting from both the metabolic (prediabetic) and affective (anxiety) disorders than metformin. Molecular studies showed that recovery was associated with the upregulation of few nuclear sirtuins that act epigenetically - Sirt 1 and 7, which were significantly attenuated in the striatum of prediabetic rats. In conclusion, our study showed that hyper-anxiety associated with prediabetic condition is ameliorated by resveratrol through modulation of sirtuins, which is more or less similar to metformin.

Topics: Animals; Antioxidants; Anxiety Disorders; Blood Glucose; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Diet; Epigenesis, Genetic; Fructose; Gene Expression Regulation; Humans; Hyperglycemia; Hypoglycemic Agents; Insulin; Insulin Resistance; Metformin; Prediabetic State; Rats; Resveratrol; Sirtuin 1; Sirtuins; Stilbenes

Resveratrol (trans-3,5,4'-trihydroxystilbene) is a nutritional supplement with anti-inflammatory properties. The present study investigated the long-term anti-inflammatory property of resveratrol in the retinas of type 2 diabetic rats. Male Wistar rats were divided into four groups: normal control, diabetic control, resveratrol-treated normal rats and resveratrol-treated diabetic rats. Type 2 diabetes was induced by a single dose injection of streptozotocin (50 mg/kg; i.p.) 15 min after the administration of nicotinamide (110 mg/kg; i.p.) in 12-h fasted rats (the streptozotocin-nicotinamide type 2 diabetic model). Oral resveratrol administration (5 mg/kg per day for 4 months) significantly improved glucose tolerance, and alleviated hyperglycemia and weight loss in diabetic rats. Furthermore, resveratrol administration significantly decreased the elevated levels of nuclear factor-κB activity, and mRNA expression, tumour necrosis factor alpha level and apoptotic cells in the retinas of the diabetic rats. Furthermore, resveratrol did not significantly affect plasma insulin levels. Long-term resveratrol administration has beneficial anti-inflammatory properties in a rat model of diabetes. However, whether resveratrol exerts its effects directly or through reducing blood glucose levels requires further investigation.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Blood Glucose; Diabetes Mellitus, Type 2; Inflammation Mediators; Insulin; Male; Rats; Rats, Wistar; Resveratrol; Retina; Stilbenes

Mice with deletion of insulin receptor substrate (IRS) 2 develop hyperglycaemia, impaired hepatic insulin signaling and elevated gluconeogenesis. Protein tyrosine phosphatase 1B (PTP1B) inhibition by resveratrol improves peripheral insulin sensitivity of these mice. Although resveratrol activates Sirtuin1 (Sirt1), the mechanisms underlying its beneficial effects are not totally elucidated. In this study, we have investigated whether Sirt1 mediates the effects of resveratrol in controlling insulin resistance in diabetic mice.. We attempted to ameliorate peripheral insulin resistance in two diabetic models, Irs2-deficient (Irs2(-/-)) mice and streptozotocin (STZ)-injected mice by resveratrol treatment or Sirt1 overexpression. Resveratrol improved systemic insulin sensitivity of Irs2-deficient mice. Irs2-deficient mice are characterized by high levels of PTP1B expression in liver and muscle. Interestingly, resveratrol decreased PTP1B in both tissues, thereby restoring IRS1-mediated insulin signaling. Moreover, resveratrol also restored insulin sensitivity and hepatic insulin signaling in STZ-diabetic mice. In contrast, moderate overexpression of Sirt1 neither normalized PTP1B levels nor restored insulin signaling in Irs2-deficient mice or STZ-diabetic mice.. Resveratrol improves peripheral insulin signaling independently of Sirt1 in diabetic mice in association with the inhibition of PTP1B and, therefore, this polyphenol could be an effective adjuvant for the treatment of diabetes.

Topics: Animals; Antioxidants; Crosses, Genetic; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Dietary Supplements; Enzyme Inhibitors; Female; Hypoglycemic Agents; Insulin Receptor Substrate Proteins; Insulin Resistance; Islets of Langerhans; Liver; Male; Mice, 129 Strain; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Muscle, Skeletal; Protein Tyrosine Phosphatase, Non-Receptor Type 1; Resveratrol; Sirtuin 1; Stilbenes

This study aimed at examining the cardioprotective effects of resveratrol in rats with simultaneous type 2 diabetes and renal hypertension. Eight groups (8-10 each) of male Sprague-Dawley rats, including a control, a diabetic, a renal hypertensive, a sham, a simultaneously hypertensive-diabetic receiving vehicle, and 3 simultaneously hypertensive-diabetic receiving resveratrol at 5, 10 or 20 mg/kg/day were used. After 4 weeks of treatment, blood pressure and glucose, and serum markers of oxidative stress were measured, and animals' hearts were used for isolated studies. Resveratrol prevented the increase of systolic blood pressure, serum malondialdehyde, fasting blood glucose, infarct size, coronary resistance, and coronary effluent creatine kinase-MB. Moreover, it prevented the decrease of serum superoxide dismutase and glutathione reductase, heart rate, left ventricular developed pressure, rate of increase of ventricular pressure, and rate of decrease of ventricular pressure. In conclusion, our findings show that resveratrol alleviates cardiac dysfunction in diabetic-hypertensive rats by virtue of antioxidant, antihypertensive, and coronary vasodilating activities.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Heart Diseases; Hypertension, Renal; Male; Rats; Rats, Sprague-Dawley; Resveratrol; Stilbenes

A defect in neo-vascularization process involving circulating angiogenic mononuclear cells (CACs) dysfunction is associated with diabetes. We showed that oxidative stress was elevated in CACs cultured from blood of individuals with metabolic syndrome (MetS) and diabetes. We then assessed the action of palmitic acid (PA), a deregulated and increased NEFA in metabolic disorders, focusing on its oxidant potential. We observed that the phyto-polyphenol resveratrol normalized oxidative stress both in CACs isolated from MetS patients or treated with PA. Resveratrol further decreased the deleterious action of PA on gene expression of vascularization factors (TNFα, VEGF-A, SDF1α, PECAM-1, VEGFR2, Tie2 and CXCR4) and improved CAC motility. Particularly, resveratrol abolished the PA-induced over-expression of the pro-oxidant protein p66Shc. Neither KLF2 nor SIRT1, previously shown in resveratrol and p66Shc action, was directly involved. Silencing p66Shc normalized PA action on VEGF-A and TNFα specifically, without abolishing the PA-induced oxidative stress, which suggests a deleterious role of p66Shc independently of any major modulation of the cellular oxidative status in a high NEFA levels context. Besides showing that resveratrol reverses PA-induced harmful effects on human CAC function, certainly through profound cellular modifications, we establish p66Shc as a major therapeutic target in metabolic disorders, independent from glycemic control.

Topics: Antioxidants; Case-Control Studies; Cell Movement; Cells, Cultured; Diabetes Mellitus, Type 2; Gene Expression Regulation; Gene Silencing; Humans; Leukocytes, Mononuclear; Male; Metabolic Syndrome; Middle Aged; Neovascularization, Physiologic; Oxidative Stress; Palmitic Acid; Resveratrol; Shc Signaling Adaptor Proteins; Src Homology 2 Domain-Containing, Transforming Protein 1; Stilbenes

Diabetic vascular complication is one of the manifestations of endothelial dysfunction. Resveratrol (RV) is considered to be beneficial in protecting endothelial function. However, the exact protective effect and mechanisms involved have not been fully clarified. In this study, we investigated the relationship between Akt/endothelial nitric oxide synthase (eNOS) activation and RV in diabetes-induced endothelial dysfunction. Aortas were dissected and placed in organ chambers, and nitric oxide (NO) production in response to acetylcholine (ACh) and RV was measured. ACh-induced endothelium-dependent relaxation was markedly increased in controls by RV pretreatment. Furthermore, RV caused NO-dependent relaxation via the Akt signaling pathway, which was weaker in the aortas of diabetic mice than age-matched controls. To further examine the underlying mechanisms, we measured the phosphorylation of Akt and eNOS by Western blotting. RV caused the phosphorylation of Akt and eNOS in aortas, which was decreased in diabetic mice. However, RV augmented the impaired clonidine-induced relaxation in diabetic mice. Interestingly, the phosphorylation of Akt and eNOS was increased under stimulation with RV and clonidine only in diabetic mice. Thus, either RV or clonidine causes Akt-dependent NO-mediated relaxation, which is weaker in diabetic mice than controls. However, additional exposure to RV and clonidine has an augmenting effect on the Akt/eNOS signaling pathway under diabetic conditions. RV-induced Akt/eNOS activity may be a common link involved in the clonidine-induced Akt/eNOS activity, so RV and clonidine may have a synergistic effect.

Topics: Adrenergic alpha-2 Receptor Agonists; Animals; Antioxidants; Clonidine; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Diabetic Angiopathies; Drug Synergism; Endothelium, Vascular; Male; Mice, Inbred ICR; Nitric Oxide Synthase; Phosphorylation; Plant Extracts; Proto-Oncogene Proteins c-akt; Resveratrol; Stilbenes; Vasodilation

To evaluate the in vitro effects of resveratrol (RSV) incubation on platelets from compensated and decompensated diabetic patients in order to use it as an adjuvant therapy. The study was performed on 77 diabetic patients and divided into two phases: 29 compensated and 48 decompensated diabetic platelets were analyzed at recruitment (T₀) and after in vitro RSV incubation (20 μg/ml) for 3 h at 37 °C (T₁). Lipoperoxide and nitric oxide (NO) levels, superoxide dismutase (SOD) and Na(+)/K(+) ATPase activities, total antioxidant capacity (TAC), and membrane fluidity tested by anisotropy of fluorescent probes TMA-DPH and DPH were determined. In vitro RSV incubation counteracts oxidative damage associated with diabetes and its complications; it is able to improve platelet function through augmented membrane fluidity and Na(+)/K(+) ATPase activity; it enhances antioxidant systems' functionality by increasing NO levels, SOD activity, and TAC and by decreasing lipoperoxide levels in both compensated and decompensated patients. Such platelet functionality enhancement suggests a new method of secondary prevention of complications associated with platelet dysfunction. Being free from one of the major risks associated with many antidiabetic agents, it can be assumed that RSV utilization in the diabetic diet may have a preventive and protective role in the progression of diabetic oxidative damage.

Topics: Adult; Aged; Antioxidants; Blood Platelets; Cells, Cultured; Diabetes Mellitus, Type 1; Diabetes Mellitus, Type 2; Female; Humans; Male; Membrane Fluidity; Middle Aged; Oxidative Stress; Resveratrol; Stilbenes

Resveratrol (RSV), 3,5,4'-trihydroxy-trans-stilbene, is known to have many beneficial physiological activities. We have synthesized several stilbene analogues and have reported that the hydroxyl group in the 4' position of RSV exhibited strong radical scavenging action. Using stilbene analogs, we investigated the structure of RSV to explain its protective effect against obesity and type 2 diabetes. All six analogs used in this study inhibited the differentiation of 3T3-L1 adipocytes. 3-Hydroxy-trans stilbene (3(OH)ST), and 3,4'-dihydroxy-trans stilbene (3,4'(OH)2ST) increased glucose uptake and induced adenosine monophosphate kinase (AMPK) phosphorylation in C2C12 myotubes independently of insulin. An in vivo study using mice fed high-fat diets indicated that 3(OH)ST was more effective than RSV in improving insulin resistance. In conclusion, RSV and its derivatives, particularly 3(OH)ST, inhibited adipocyte differentiation and enhanced glucose uptake in the myotubes, resulting in a reduction of obesity and an improvement in glucose tolerance in vivo.

Topics: 3T3-L1 Cells; Adipocytes; AMP-Activated Protein Kinases; Animals; Diabetes Mellitus, Type 2; Disease Models, Animal; Glucose; Humans; Insulin; Insulin Resistance; Mice; Obesity; Resveratrol; Stilbenes

Eating a "Westernized" diet high in fat and sugar leads to weight gain and numerous health problems, including the development of type 2 diabetes mellitus (T2DM). Rodent studies have shown that resveratrol supplementation reduces blood glucose levels, preserves β-cells in islets of Langerhans, and improves insulin action. Although rodent models are helpful for understanding β-cell biology and certain aspects of T2DM pathology, they fail to reproduce the complexity of the human disease as well as that of nonhuman primates. Rhesus monkeys were fed a standard diet (SD), or a high-fat/high-sugar diet in combination with either placebo (HFS) or resveratrol (HFS+Resv) for 24 months, and pancreata were examined before overt dysglycemia occurred. Increased glucose-stimulated insulin secretion and insulin resistance occurred in both HFS and HFS+Resv diets compared with SD. Although islet size was unaffected, there was a significant decrease in β-cells and an increase in α-cells containing glucagon and glucagon-like peptide 1 with HFS diets. Islets from HFS+Resv monkeys were morphologically similar to SD. HFS diets also resulted in decreased expression of essential β-cell transcription factors forkhead box O1 (FOXO1), NKX6-1, NKX2-2, and PDX1, which did not occur with resveratrol supplementation. Similar changes were observed in human islets where the effects of resveratrol were mediated through Sirtuin 1. These findings have implications for the management of humans with insulin resistance, prediabetes, and diabetes.

Topics: Animals; Blood Glucose; Body Weight; Cell Dedifferentiation; Densitometry; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Diet, High-Fat; Dietary Sucrose; Disease Models, Animal; Fluorescent Antibody Technique; Glucagon; Glucagon-Like Peptide 1; Glucagon-Secreting Cells; Glucose Tolerance Test; Glycated Hemoglobin; Homeobox Protein Nkx-2.2; Homeodomain Proteins; Insulin; Insulin Resistance; Insulin-Secreting Cells; Islets of Langerhans; Macaca mulatta; Nuclear Proteins; Protective Agents; Resveratrol; Sirtuin 1; Stilbenes; Transcription Factors

Hepatocellular carcinoma is the most common type of liver cancer. The risk of hepatocellular carcinoma for type 2 diabetic patients is greater than that for non-diabetic individuals although the mechanism is unclear. The cancer suppressor resveratrol inhibits cancer cell proliferation partly through the STAT3 signaling pathway. However, the effects of resveratrol on STAT3 in high glucose-exposed HepG2 cells and the role of SIRT1 are not clear to date. The aim of the present study was to investigate the effects of resveratrol on STAT3 and SIRT1 regarding the proliferation of high glucose-exposed HepG2 cells. HepG2 cells were cultured in DMEM containing glucose (2.8, 5.5 and 25 mM) and resveratrol (0, 10 and 100 µM). HepG2 cell proliferation and viability were analyzed by MTT assays. The levels of p-STAT3 and SIRT1 were analyzed by western blotting, and RT-PCR methods were used to detect the transcription levels of cyclin B1, cyclin D1, VEGF and MMP-9. SIRT1-specific short-interfering RNA was used to investigate the role of SIRT1 in p-STAT3 signaling. A high glucose concentration (25 mM) induced HepG2 cell proliferation. This effect was suppressed by resveratrol (100 µM), and the effect on the p-STAT3 signaling pathway was found to be SIRT1-dependent. Our findings may provide new insights into the mechanism by which resveratrol suppresses HepG2 cell proliferation under conditions of high glucose. Furthermore, this information may provide the basis for a novel therapeutic strategy for hepatocellular carcinoma patients suffering from either diabetes or hyperglycemia.

Topics: Carcinoma, Hepatocellular; Cell Proliferation; Cell Survival; Diabetes Mellitus, Type 2; Gene Expression Regulation, Neoplastic; Glucose; Hep G2 Cells; Humans; Liver Neoplasms; Resveratrol; RNA, Small Interfering; Signal Transduction; Sirtuin 1; STAT3 Transcription Factor; Stilbenes

Mitochondrial dysfunction and reactive oxygen species (ROS) have been implicated in the aetiology of skeletal muscle insulin resistance, although there is considerable controversy regarding these concepts. Mitochondrial function has been traditionally assessed in the presence of saturating ADP, but ATP turnover and the resultant ADP is thought to limit respiration in vivo. Therefore, we investigated the potential link between submaximal ADP-stimulated respiration rates, ROS generation and skeletal muscle insulin sensitivity in a model of type 2 diabetes mellitus, the ZDF rat. Utilizing permeabilized muscle fibres we observed that submaximal ADP-stimulated respiration rates (250-2000 μm ADP) were lower in ZDF rats than in lean controls, which coincided with decreased adenine nucleotide translocase 2 (ANT2) protein content. This decrease in submaximal ADP-stimulated respiration occurred in the absence of a decrease in electron transport chain function. Treating ZDF rats with resveratrol improved skeletal muscle insulin resistance and this was associated with elevated submaximal ADP-stimulated respiration rates as well as an increase in ANT2 protein content. These results coincided with a greater ability of ADP to attenuate mitochondrial ROS emission and an improvement in cellular redox balance. Together, these data suggest that mitochondrial dysfunction is present in skeletal muscle insulin resistance when assessed at submaximal ADP concentrations and that ADP dynamics may influence skeletal muscle insulin sensitivity through alterations in the propensity for mitochondrial ROS emission.

Topics: Adenine Nucleotide Translocator 2; Adenosine Diphosphate; Animals; Cell Respiration; Diabetes Mellitus, Type 2; Glutathione; Glutathione Disulfide; Hydrogen Peroxide; Insulin Resistance; Male; Mitochondria; Muscle, Skeletal; Rats; Rats, Zucker; Resveratrol; Stilbenes

Type 2 diabetes mellitus (T2DM) is associated with an increased risk of macrovascular disease. Epidemiological studies suggest that plant polyphenol resveratrol (REV) is associated with reduced risk of cardiovascular diseases. Since chronic inflammatory and endotheliar cell activation play a critical role in vascular aging and atherogenesis, we evaluated whether REV can inhibit inflammatory-induced vascular injury in T2DM. We found that REV (50 mg/kg/d) can regulate glucose and lipid metabolism, improve insulin resistance and vascular permeability, and protect against the foam cells and cholesterol crystals formation in arterial vessel walls of T2DM rats. The protective effects of REV were consistent with the decrease in nuclear translocation of nuclear factor kappa B (NF-kappa B) and there down-regulation of interleukin-1 beta (IL-1β) and interleukin-6 (IL-6) levers in blood and tumor necrosis factor-alpha (TNF-α), intercellular adhesion molecule-1 (ICAM-1), and monocyte chemoattractant protein-1 (MCP-1) expressions in vascular wall. In addition, REV (10 and 100 nmol/L) treatment protected cultured endothelial cells against increases in the expression of TNF-α, ICAM-1, and MCP-1 mRNA and protein induced by high glucose via inhibiting nuclear translocation of NF-kappa B p65. The specific NF-kappa B inhibitor pyrrolidine dithiocarbamate- (PDTC-) or small interfering RNA directed against NF-kappa B p65-mediated downregulation of NF-kappa B p65 was further enhanced by REV (100 nmol/L) in the human endothelial cell line EZ.hy926. In conclusion, these observations suggest that chronic treatment of T2DM rats with REV attenuates the inflammatory injury of the vascular wall and the effects are associated with down-regulation of the NF-kappa B signal pathway.

Topics: Animals; Aorta, Thoracic; Capillary Permeability; Carotid Arteries; Carotid Artery Injuries; Cell Line; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Diet, High-Fat; Endothelial Cells; Humans; Hypoglycemic Agents; Insulin; Interleukin-1beta; Interleukin-6; Lipids; Male; NF-kappa B; Rats; Rats, Sprague-Dawley; Resveratrol; Stilbenes

Many of the effects of resveratrol are consistent with the activation of AMP-activated protein kinase (AMPK), silent information regulator T1 (SIRT1) and peroxisome proliferator-activated receptor (PPAR)γ co-activator 1α (PGC-1α), which play key roles in the regulation of lipid and glucose homeostasis, and in the control of oxidative stress. We investigated whether resveratrol has protective effects on the kidney in type 2 diabetes.. Four groups of male C57BLKS/J db/m and db/db mice were used in this study. Resveratrol was administered via gavage to diabetic and non-diabetic mice, starting at 8 weeks of age, for 12 weeks.. The db/db mice treated with resveratrol had decreased albuminuria. Resveratrol ameliorated glomerular matrix expansion and inflammation. Resveratrol also lowered the NEFA and triacylglycerol content of the kidney, and this action was related to increases in the phosphorylation of AMPK and the activation of SIRT1-PGC-1α signalling and of the key downstream effectors, the PPARα-oestrogen-related receptor (ERR)-1α-sterol regulatory element-binding protein 1 (SREBP1). Furthermore, resveratrol decreased the activity of phosphatidylinositol-3 kinase (PI3K)-Akt phosphorylation and class O forkhead box (FOXO)3a phosphorylation, which resulted in a decrease in B cell leukaemia/lymphoma 2 (BCL-2)-associated X protein (BAX) and increases in BCL-2, superoxide dismutase (SOD)1 and SOD2 production. Consequently, resveratrol reversed the increase in renal apoptotic cells and oxidative stress, as reflected by renal 8-hydroxy-deoxyguanosine (8-OH-dG), urinary 8-OH-dG and isoprostane concentrations. Resveratrol prevented high-glucose-induced oxidative stress and apoptosis in cultured mesangial cells through the phosphorylation of AMPK and activation of SIRT1-PGC-1α signalling and the downstream effectors, PPARα-ERR-1α-SREBP1.. The results suggest that resveratrol prevents diabetic nephropathy in db/db mice by the phosphorylation of AMPK and activation of SIRT1-PGC-1α signalling, which appear to prevent lipotoxicity-related apoptosis and oxidative stress in the kidney.

Topics: AMP-Activated Protein Kinases; Animals; Cells, Cultured; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Enzyme Activation; Kidney; Lipid Metabolism; Lipotropic Agents; Male; Mesangial Cells; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Oxidative Stress; Protective Agents; Protein Processing, Post-Translational; Resveratrol; RNA Interference; Signal Transduction; Sirtuin 1; Stilbenes; Transcription Factors

The present study was designed to evaluate whether long-term resveratrol administration has beneficial effects on the metabolic control and oxidative stress in diabetic rats.. Male Wistar rats were divided into four groups: normal control, diabetic control, normal treated with resveratrol, and diabetic treated with resveratrol. Diabetes was induced by injection of streptozotocin (50 mg/kg; i.p.), fifteen minutes after the administration of nicotinamide (110 mg/kg; i.p.) in 12 h fasted rats.. Four-month oral resveratrol administration (5 mg/kg/day) significantly attenuated the elevated levels of the blood glucose, glycosylated hemoglobin, total protein, albumin, urea, creatinine, and 8-isoprostane in diabetic rats. Moreover, resveratrol administration to diabetic rats improved the reduced levels of glutathione, total antioxidant capacity, and the antioxidant enzymes activities (superoxide dismutase, glutathione peroxidase, and catalase). No significant differences were observed in the activities of plasma aminotransferases (ALT and AST) and insulin levels between diabetic rats treated with resveratrol and diabetic controls.. The results suggest that chronic resveratrol administration is safe and effective, and may be considered as a beneficial therapeutic compound in diabetes.

Topics: Alanine Transaminase; Animals; Antioxidants; Aspartate Aminotransferases; Catalase; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Disease Models, Animal; Glutathione Peroxidase; Glutathione Peroxidase GPX1; Hyperglycemia; Male; Oxidative Stress; Rats; Rats, Wistar; Resveratrol; Stilbenes; Superoxide Dismutase

The skeletal muscle cells are one of the main sites of glucose uptake through glucose transporter 4 (GLUT4) in response to insulin. In muscle cells, 5' adenosine monophosphate-activated protein kinase (AMPK) is known as another GLUT4 translocation promoter. Natural compounds that activate AMPK have a possibility to overcome insulin resistance in the diabetic state. Piceatannol is a natural analog and a metabolite of resveratrol, a known AMPK activator. In this study, we investigate the in vitro effect of piceatannol on glucose uptake, AMPK phosphorylation and GLUT4 translocation to plasma membrane in L6 myocytes, and its in vivo effect on blood glucose levels in type 2 diabetic model db/db mice. Piceatannol was found to promote glucose uptake, AMPK phosphorylation and GLUT4 translocation by Western blotting analyses in L6 myotubes under a condition of insulin absence. Promotion by piceatannol of glucose uptake as well as GLUT4 translocation to plasma membrane by immunocytochemistry was also demonstrated in L6 myoblasts transfected with a glut4 cDNA-coding vector. Piceatannol suppressed the rises in blood glucose levels at early stages and improved the impaired glucose tolerance at late stages in db/db mice. These in vitro and in vivo findings suggest that piceatannol may be preventive and remedial for type 2 diabetes and become an antidiabetic phytochemical.

Topics: AMP-Activated Protein Kinase Kinases; Animals; Blood Glucose; Cell Line; Cell Membrane; Diabetes Mellitus, Type 2; Disease Models, Animal; Enzyme Activation; Glucose; Glucose Transporter Type 4; Mice; Molecular Imaging; Muscle Cells; Protein Kinases; Rats; Resveratrol; Stilbenes

This study investigated the effects of resveratrol (RV) on diabetes-related metabolic changes in a spontaneous model of type 2 diabetes, as well as activation of AMP-activated protein kinase (AMPK) and downstream targets.. C57BL/KsJ-db/db mice were fed a normal diet with RV (0.005% and 0.02%, w/w) or rosiglitazone (RG, 0.001%, w/w) for 6 weeks. Both doses of RV significantly decreased blood glucose, plasma free fatty acid, triglyceride, apo B/apo AІ levels and increased plasma adiponectin levels. RV activated AMPK and downstream targets leading to decreased blood HbA1c levels, hepatic gluconeogenic enzyme activity, and hepatic glycogen, while plasma insulin levels, pancreatic insulin protein, and skeletal muscle GLUT4 protein were higher after RV supplementation. The high RV dose also significantly increased hepatic glycolytic gene expression and enzyme activity, along with skeletal muscle glycogen synthase protein expression, similar to RG. Furthermore, RV dose dependently decreased hepatic triglyceride content and phosphorylated I kappa B kinase (p-IKK) protein expression, while hepatic uncoupling protein (UCP) and skeletal muscle UCP expression were increased.. RV potentiates improving glycemic control, glucose uptake, and dyslipidemia, as well as protecting against pancreatic β-cell failure in a spontaneous type 2 diabetes model. Dietary RV has potential as an antidiabetic agent via activation of AMPK and its downstream targets.

Topics: Adiponectin; AMP-Activated Protein Kinases; Animals; Blood Glucose; Body Weight; Diabetes Mellitus, Type 2; Dietary Supplements; Dyslipidemias; Glucose Transporter Type 4; Glycated Hemoglobin; Glycogen; Insulin; Insulin Secretion; Liver; Male; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Muscle, Skeletal; Resveratrol; Rosiglitazone; Stilbenes; Thiazolidinediones; Triglycerides

Reduced mitochondrial capacity in skeletal muscle has been suggested to underlie the development of insulin resistance and type 2 diabetes mellitus (T2DM). However, data obtained from human subjects concerning this putative relation indicate that the mitochondrial defect observed in diabetic muscle might be secondary to the insulin-resistant state instead of being a causal factor. Nonetheless, diminished mitochondrial function, even secondary to insulin resistance, may accelerate lipid deposition in non-adipose tissues and aggravate insulin resistance. Indeed, improving mitochondrial capacity via exercise training and calorie restriction is associated with positive metabolic health effects. Here we review muscle mitochondrial dysfunction in humans and propose that targeting muscle mitochondria to improve muscle oxidative capacity should be considered as a strategy for improving metabolic health.

Topics: Animals; Diabetes Mellitus, Type 2; Humans; Insulin Resistance; Mitochondria, Muscle; Resveratrol; Stilbenes

Recent studies have suggested resveratrol (RSV) as a new natural therapeutic agent to treat type 2 diabetes and lipid-induced insulin resistance. Here, we investigated whether RSV could reverse palmitate-induced insulin resistance in human primary muscle cells.. Myotubes obtained from six healthy men (54 ± 3 years (mean ± SE), BMI 25.0 ± 1.7 kg/m(2), fasting plasma glucose concentration (fP-glucose) 5.47 ± 0.09 mmol/l) were treated for 4 h with 100 μmol/l RSV and/or 0.2 mmol/l palmitate, and stimulated with or without 100 nmol/l insulin. Assays of glucose uptake, glycogen synthesis, palmitate oxidation, intracellular signalling and AMP-activated protein kinase (AMPK) activity were performed.. RSV did not reverse palmitate-induced impairment of glucose metabolism. Surprisingly, RSV decreased glucose uptake and glycogen synthesis in human skeletal muscle cells. Palmitate oxidation and phosphorylation of AMPK and its downstream target acetyl-CoA carboxylase β (ACCβ) were inhibited by RSV, and RSV completely blocked the activity of AMPK isoform complexes α1/β2/γ1 and α2/β2/γ1 in in-vitro kinase activity assays. Endoplasmic reticulum (ER) stress was increased in response to RSV, as indicated by increased phosphorylation of eukaryotic initiation factor 2α (eIF2α) and increased expression of CCAAT/enhancer binding protein homologous protein (CHOP).. Acute exposure to RSV inhibits AMPK activity, fatty-acid oxidation and glucose metabolism in human myotubes.

Topics: AMP-Activated Protein Kinases; Cell Differentiation; Diabetes Mellitus, Type 2; Drug Interactions; Enzyme Inhibitors; Glucose; Glycogen; Humans; Insulin Resistance; Male; Middle Aged; Muscle Fibers, Skeletal; Palmitates; Phosphorylation; Primary Cell Culture; Resveratrol; Signal Transduction; Stilbenes

We aimed to investigate specific roles of mitogen-activated protein kinases (MAPK) in the deterioration of endothelial function during the progression of diabetes and the potential therapeutic effects of MAPK inhibitors and agonists in the amelioration of endothelial function. Protein expression and phosphorylation of p38, c-Jun NH(2)-terminal kinase (JNK), and extracellular signal-regulated kinase (Erk) were assessed in mesenteric arteries of 3- (3M) and 9-month-old (9M) male diabetic and control mice. The expression of p38, JNK, and Erk was comparable in all groups of mice, but the phosphorylation of p38 and JNK was increased in 3M and further increased in 9M diabetic mice, whereas the phosphorylation of Erk was substantially reduced in 9M diabetic mice. NADPH oxidase-dependent superoxide production was significantly increased in vessels of two ages of diabetic mice. Inhibition of either p38 with SB203580 or JNK with SP600125 reduced superoxide production and improved shear stress-induced dilation (SSID) in 3M, but not in 9M, diabetic mice. Treating the vessels of 9M diabetic mice with resveratrol increased Erk phosphorylation and shear stress-induced endothelial nitric oxide synthase (eNOS) phosphorylation and activity, but resveratrol alone did not improve SSID. Administration of resveratrol and SB203580 or resveratrol and SP600125 together significantly improved SSID in vessels of 9M diabetic mice. The improved response was prevented by U0126, an Erk inhibitor. Thus, p38/JNK-dependent increase in oxidative stress diminished nitric oxide-mediated dilation in vessels of 3M diabetic mice. Oxidative stress and impaired Erk-dependent activation of eNOS exacerbates endothelial dysfunction in the advanced stage of diabetes.

Topics: Animals; Anthracenes; Butadienes; Diabetes Mellitus, Type 2; Extracellular Signal-Regulated MAP Kinases; Imidazoles; Immunoblotting; JNK Mitogen-Activated Protein Kinases; Male; Mice; Mitogen-Activated Protein Kinases; Nitriles; Oxidative Stress; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Pyridines; Receptors, Leptin; Resveratrol; Signal Transduction; Stilbenes; Superoxides

Resveratrol (RSV) has anti-inflammatory and anti-oxidant actions which may contribute to its cardiovascular protective effects. We examined whether RSV has any beneficial effects on pancreatic islets in db/db mice, an animal model of type 2 diabetes. The db/db and db/dm mice (non-diabetic control) were treated with (db-RSV) or without RSV (db-control) (20 mg/kg daily) for 12 weeks. After performing an intraperitoneal glucose tolerance test and insulin tolerance test, mice were sacrificed, the pancreas was weighed, pancreatic β-cell mass was quantified by point count method, and the amount of islet fibrosis was determined. 8-Hydroxydeoxyguanosine (8-OHdG), an oxidative stress marker, was determined in 24 h urine and pancreatic islets. RSV treatment significantly improved glucose tolerance at 2 hrs in db/db mice (P = 0.036), but not in db/dm mice (P = 0.623). This was associated with a significant increase in both pancreas weight (P = 0.011) and β-cell mass (P = 0.016). Islet fibrosis was much less in RSV-treated mice (P = 0.048). RSV treatment also decreased urinary 8-OHdG levels (P = 0.03) and the percentage of islet nuclei that were positive for 8-OHdG immunostaining (P = 0.019). We conclude that RSV treatment improves glucose tolerance, attenuates β-cell loss, and reduces oxidative stress in type 2 diabetes. These findings suggest that RSV may have a therapeutic implication in the prevention and management of diabetes.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Antioxidants; Blood Glucose; Deoxyguanosine; Diabetes Mellitus, Type 2; Disease Models, Animal; Fibrosis; Glucose Tolerance Test; Immunohistochemistry; Insulin; Insulin Resistance; Islets of Langerhans; Male; Mice; Organ Size; Oxidative Stress; Resveratrol; Stilbenes

In the present study, resveratrol, a polyphenolic SIRT1 activator was evaluated for its SIRT1 activation in an in vitro fluorescent based assay (EC(50) : 7 μM). The efficacy of resveratrol was also evaluated in ob/ob mice for its antidiabetic and associated metabolic effects. Mice aged 5-8 weeks were included in four groups; control and resveratrol at 5, 15, 50 mg/kg, b.i.d. and were dosed orally. After 4 weeks of drug treatment, body weights were noted and random blood glucose and insulin was estimated for the antidiabetic effect. Animals were also subjected to the oral glucose tolerance test to observe any improvement in the glucose excursion. Triglycerides, total cholesterol, adiponectin and free fatty acid levels were also estimated. The results showed that resveratrol exhibited significant antihyperglycemic activity with an improvement in the insulin levels compared with the control mice. There was also a significant improvement observed in the glucose excursion in the oral glucose tolerance test performed for 120 min; although an insignificant improvement in the triglycerides, total cholesterol, adiponectin and free fatty acid levels was observed at different doses of resveratrol tested. The present findings suggest that resveratrol is an antihyperglycemic agent and drugs similar to resveratrol can be considered as an effective therapeutic adjuvant for the current treatment of diabetes mellitus.

Topics: Adiponectin; Animals; Body Weight; Chemotherapy, Adjuvant; Cholesterol; Diabetes Mellitus, Type 2; Enzyme Activation; Fatty Acids, Nonesterified; Glucose; Glucose Tolerance Test; Hypoglycemic Agents; Insulin; Mice; Resveratrol; Sirtuin 1; Stilbenes; Triglycerides

Abnormal aggregation of islet amyloid polypeptide (IAPP) into amyloid fibrils is a hallmark of type 2 diabetes. In this study, we investigated the initial oligomerization and subsequent addition of monomers to growing aggregates of human IAPP at the residue-specific level using NMR, atomic force microscopy, mass spectroscopy, and computational simulations. We found that in solution IAPPs rapidly associate into transient low-order oligomers such as dimers and trimers via interactions between histidine 18 and tyrosine 37. This initial event is proceeded by slow aggregation into higher-order spherical oligomers and elongated fibrils. In these two morphologically distinct types of aggregates IAPPs adopt structures with markedly different residual flexibility. Here we show that the anti-amyloidogenic compound resveratrol inhibits oligomerization and amyloid formation via binding to histidine 18, supporting the finding that this residue is crucial for on-pathway oligomer formation.

Topics: Amyloid; Diabetes Mellitus, Type 2; Humans; Islet Amyloid Polypeptide; Microscopy, Atomic Force; Nuclear Magnetic Resonance, Biomolecular; Protein Multimerization; Resveratrol; Stilbenes

The protein deacetylase SIRT1, and its activator resveratrol, exert beneficial effects on glucose metabolism. Different SIRT1 targets have been identified, including PTP1B, AMPK, FOXO, PGC-1α and IRS2. The latter may underscore a tight link between SIRT1 and insulin signaling components. However, whether SIRT1 has a direct effect on insulin resistance and whether resveratrol acts directly or indirectly in this context is still a matter of controversy and this question has not been addressed in muscle cells. Here, we show that SIRT1 protein expression is decreased in muscle biopsies and primary myotubes derived from type 2 diabetic patients, suggesting a contribution of diminished SIRT1 in the determination of muscle insulin resistance. To investigate the functional impact of SIRT1 on the insulin pathway, the activation of insulin downstream effector PKB was evaluated after SIRT1 inactivation by RNAi, SIRT1 overexpression, or resveratrol treatments. In muscle cells and HEK293 cells, downregulation of SIRT1 reduced, while overexpression increased, insulin-induced PKB activatory phosphorylation. Further molecular characterisation revealed that SIRT1 interacts in an insulin-independent manner with the PI3K adapter subunit p85. We then investigated whether resveratrol may improve insulin signaling in muscle cells via SIRT1, or alternative targets. Incubation of muscle cells with resveratrol reverted the insulin-resistant state induced by prolonged TNFα or insulin treatment. Resveratrol-dependent improvement of insulin-resistance occurred through inhibition of serine phosphorylation of IRS1/2, implicating resveratrol as a serine kinase inhibitor. Finally, a functional interaction between PI3K and SIRT1 was demonstrated in C. elegans, where constitutively active PI3K - mimicking increased IIS signaling - lead to shortened lifespan, while removal of sir-2.1 abolished PI3K-induced lifespan shortening. Our data identify SIRT1 as a positive modulator of insulin signaling in muscle cells through PI3K, and this mechanism appears to be conserved from C. elegans through humans.

Topics: Adult; Animals; Animals, Genetically Modified; Caenorhabditis elegans; Case-Control Studies; Cell Line; Diabetes Mellitus, Type 2; Enzyme Inhibitors; Humans; Insulin; Insulin Receptor Substrate Proteins; Insulin Resistance; Longevity; Middle Aged; Muscle Fibers, Skeletal; Phosphatidylinositol 3-Kinases; Phosphorylation; Protein Binding; Recombinant Fusion Proteins; Resveratrol; RNA Interference; Signal Transduction; Sirtuin 1; Stilbenes; Tumor Necrosis Factor-alpha

Despite the beneficial effects of resveratrol (RSV) on cardiovascular disease and life span, its effects on type 2 diabetic nephropathy remain unknown. This study examined the renoprotective effects of RSV in db/db mice, a model of type 2 diabetes.. db/db mice were treated with RSV (0.3% mixed in chow) for 8 weeks. We measured urinary albumin excretion (UAE), histological changes (including mesangial expansion, fibronectin accumulation, and macrophage infiltration), oxidative stress markers (urinary excretion and mitochondrial content of 8-hydroxy-2'-deoxyguanosine [8-OHdG], nitrotyrosine expression), and manganese-superoxide dismutase (Mn-SOD) activity together with its tyrosine-nitrated modification and mitochondrial biogenesis in the kidney. Blood glucose, glycated hemoglobin, and plasma lipid profiles were also measured. The phosphorylation of 5'-AMP-activated kinase (AMPK) and expression of silent information regulator 1 (SIRT1) in the kidney were assessed by immunoblotting.. RSV significantly reduced UAE and attenuated renal pathological changes in db/db mice. Mitochondrial oxidative stress and biogenesis were enhanced in db/db mice; however, Mn-SOD activity was reduced through increased tyrosine-nitrated modification. RSV ameliorated such alterations and partially improved blood glucose, glycated hemoglobin, and abnormal lipid profile in db/db mice. Activation of AMPK was decreased in the kidney of db/db mice compared with db/m mice. RSV neither modified AMPK activation nor SIRT1 expression in the kidney.. RSV ameliorates renal injury and enhanced mitochondrial biogenesis with Mn-SOD dysfunction in the kidney of db/db mice, through improvement of oxidative stress via normalization of Mn-SOD function and glucose-lipid metabolism. RSV has antioxidative activities via AMPK/SIRT1-independent pathway.

Topics: AMP-Activated Protein Kinases; Animals; Blood Glucose; Blotting, Western; Cells, Cultured; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Immunohistochemistry; Immunoprecipitation; Kidney; Male; Mice; Oxidative Stress; Resveratrol; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction; Sirtuin 1; Stilbenes; Superoxide Dismutase

The molecular structure/property-affinity relationships of dietary polyphenols non-covalently binding to total plasma proteins of type II diabetes (IIDTPP) were investigated by comparing the binding constants obtained from the fluorescence titration method. An additional methoxy group in flavonoids increased their binding affinities for IIDTPP by 1.38 to 15.85 times. The hydroxylation at the 4' position (Ring B) of flavonols and the 5 position (Ring A) of isoflavones weakened the binding affinities; however, hydroxylation at other positions on flavonoids slightly enhanced or little affected the binding affinities for IIDTPP. The glycosylation of flavonoids slightly decreased or little affected the affinities for IIDTPP by less than 1 order of magnitude. The hydrogenation of the C2[double bond, length as m-dash]C3 double bond of flavone, 6-hydroxyflavone, 6-methoxyflavone and myricetin decreased the binding affinities. The galloylation of catechins significantly improved the binding affinities with IIDTPP approximately 10 to 1000 times. The esterification of gallic acid increased its binding affinity. The hydrophobic force played an important role in the binding interaction between polyphenols and IIDTPP.

Topics: Binding Sites; Blood Proteins; Catechin; Diabetes Mellitus, Type 2; Flavanones; Flavones; Flavonols; Food; Gallic Acid; Glycosylation; Humans; Hydrogen Bonding; Hydrogenation; Hydrophobic and Hydrophilic Interactions; Hydroxylation; Isoflavones; Molecular Structure; Plants; Polyphenols; Protein Binding; Spectrometry, Fluorescence; Stilbenes; Structure-Activity Relationship

Sirtuins catalyze NAD(+)-dependent protein deacetylation and are critical regulators of transcription, apoptosis, metabolism, and aging. There are seven human sirtuins (SIRT1-7), and SIRT1 has been implicated as a key mediator of the pathways downstream of calorie restriction that have been shown to delay the onset and reduce the incidence of age-related diseases such as type 2 diabetes. Increasing SIRT1 activity, either by transgenic overexpression of the Sirt1 gene in mice or by pharmacological activation by small molecule activators resveratrol and SRT1720, has shown beneficial effects in rodent models of type 2 diabetes, indicating that SIRT1 may represent an attractive therapeutic target. Herein, we have assessed purported SIRT1 activators by employing biochemical assays utilizing native substrates, including a p53-derived peptide substrate lacking a fluorophore as well as the purified native full-length protein substrates p53 and acetyl-CoA synthetase1. SRT1720, its structurally related compounds SRT2183 and SRT1460, and resveratrol do not lead to apparent activation of SIRT1 with native peptide or full-length protein substrates, whereas they do activate SIRT1 with peptide substrate containing a covalently attached fluorophore. Employing NMR, surface plasmon resonance, and isothermal calorimetry techniques, we provide evidence that these compounds directly interact with fluorophore-containing peptide substrates. Furthermore, we demonstrate that SRT1720 neither lowers plasma glucose nor improves mitochondrial capacity in mice fed a high fat diet. SRT1720, SRT2183, SRT1460, and resveratrol exhibit multiple off-target activities against receptors, enzymes, transporters, and ion channels. Taken together, we conclude that SRT1720, SRT2183, SRT1460, and resveratrol are not direct activators of SIRT1.

Topics: Acetylation; Allosteric Regulation; Animals; Blood Glucose; Calorimetry; Diabetes Mellitus, Type 2; Dietary Fats; Enzyme Activation; Enzyme Inhibitors; Heterocyclic Compounds, 4 or More Rings; Humans; Mice; Mice, Obese; Nuclear Magnetic Resonance, Biomolecular; Resveratrol; Rhodamines; Sirtuin 1; Stilbenes; Substrate Specificity; Surface Plasmon Resonance; Tumor Suppressor Protein p53

Resveratrol is a natural phytophenol that exhibits cardioprotective effects. This study was designed to elucidate the mechanisms by which resveratrol protects against diabetes-induced cardiac dysfunction. Normal control (m-Lepr(db)) mice and type 2 diabetic (Lepr(db)) mice were treated with resveratrol orally for 4 wk. In vivo MRI showed that resveratrol improved cardiac function by increasing the left ventricular diastolic peak filling rate in Lepr(db) mice. This protective role is partially explained by resveratrol's effects in improving nitric oxide (NO) production and inhibiting oxidative/nitrative stress in cardiac tissue. Resveratrol increased NO production by enhancing endothelial NO synthase (eNOS) expression and reduced O(2)(·-) production by inhibiting NAD(P)H oxidase activity and gp91(phox) mRNA and protein expression. The increased nitrotyrosine (N-Tyr) protein expression in Lepr(db) mice was prevented by the inducible NO synthase (iNOS) inhibitor 1400W. Resveratrol reduced both N-Tyr and iNOS expression in Lepr(db) mice. Furthermore, TNF-α mRNA and protein expression, as well as NF-κB activation, were reduced in resveratrol-treated Lepr(db) mice. Both Lepr(db) mice null for TNF-α (db(TNF-)/db(TNF-) mice) and Lepr(db) mice treated with the NF-κB inhibitor MG-132 showed decreased NAD(P)H oxidase activity and iNOS expression as well as elevated eNOS expression, whereas m-Lepr(db) mice treated with TNF-α showed the opposite effects. Thus, resveratrol protects against cardiac dysfunction by inhibiting oxidative/nitrative stress and improving NO availability. This improvement is due to the role of resveratrol in inhibiting TNF-α-induced NF-κB activation, therefore subsequently inhibiting the expression and activation of NAD(P)H oxidase and iNOS as well as increasing eNOS expression in type 2 diabetes.

Topics: Animals; Antioxidants; Diabetes Mellitus, Type 2; Disease Models, Animal; Female; Magnetic Resonance Imaging; Male; Membrane Glycoproteins; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Mutant Strains; NADPH Oxidase 2; NADPH Oxidases; NF-kappa B; Nitrates; Nitric Oxide; Nitric Oxide Synthase Type III; Oxidative Stress; Oxygen; Reactive Oxygen Species; Resveratrol; Stilbenes; Tumor Necrosis Factor-alpha; Ventricular Dysfunction, Left

GRAPES FOR AMYLOIDS: The red wine compound resveratrol can effectively inhibit the formation of IAPP amyloid that is found in type II diabetes. Our in vitro inhibition results do not depend on the antioxidant activity of resveratrol. Further, the markedly enhanced cell survival in the presence of resveratrol also indicates that the small oligomeric structures that are observed during beta-sheet formation are not toxic and could be off-pathway assembly products.

Topics: Amyloid; Animals; Antioxidants; Cell Line; Diabetes Mellitus, Type 2; Humans; Insulin-Secreting Cells; Islet Amyloid Polypeptide; Molecular Structure; Protein Conformation; Rats; Resveratrol; Stilbenes; Wine

Type II diabetes mellitus (T2DM) is a disease characterized by progressive deposition of amyloid in the extracellular matrix of beta-cells. We investigated the interaction of the islet amyloid polypeptide (IAPP) with lipid model raft mixtures and INS-1E cells using fluorescence microscopy techniques. Following preferential partitioning of IAPP into the fluid lipid phase, the membrane suffers irreversible damage and predominantly circularly-shaped lipid-containing IAPP amyloid is formed. Interaction studies with the pancreatic beta-cell line INS-1E revealed that growing IAPP fibrils also incorporate substantial amounts of cellular membranes in vivo. Additionally, the inhibitory effect of the red wine compound resveratrol on IAPP fibril formation has been studied, alluding to its potential use in developing therapeutic strategies against T2DM.

Topics: Amyloid; Animals; Cell Line; Cell Membrane; Diabetes Mellitus, Type 2; Humans; Islet Amyloid Polypeptide; Membrane Lipids; Microscopy, Fluorescence; Resveratrol; Stilbenes

Pathways that regulate mitochondrial biogenesis are potential therapeutic targets for the amelioration of endothelial dysfunction and vascular disease. Resveratrol was shown to impact mitochondrial function in skeletal muscle and the liver, but its role in mitochondrial biogenesis in endothelial cells remains poorly defined. The present study determined whether resveratrol induces mitochondrial biogenesis in cultured human coronary arterial endothelial cells (CAECs). In CAECs resveratrol increased mitochondrial mass and mitochondrial DNA content, upregulated protein expression of electron transport chain constituents, and induced mitochondrial biogenesis factors (proliferator-activated receptor-coactivator-1alpha, nuclear respiratory factor-1, mitochondrial transcription factor A). Sirtuin 1 (SIRT1) was induced, and endothelial nitric oxide (NO) synthase (eNOS) was upregulated in a SIRT1-dependent manner. Knockdown of SIRT1 (small interfering RNA) or inhibition of NO synthesis prevented resveratrol-induced mitochondrial biogenesis. In aortas of type 2 diabetic (db/db) mice impaired mitochondrial biogenesis was normalized by chronic resveratrol treatment, showing the in vivo relevance of our findings. Resveratrol increases mitochondrial content in endothelial cells via activating SIRT1. We propose that SIRT1, via a pathway that involves the upregulation of eNOS, induces mitochondrial biogenesis. Resveratrol induced mitochondrial biogenesis in the aortas of type 2 diabetic mice, suggesting the potential for new treatment approaches targeting endothelial mitochondria in metabolic diseases.

Topics: Animals; Antioxidants; Aorta, Thoracic; Cells, Cultured; Diabetes Mellitus, Type 2; DNA, Mitochondrial; Electron Transport; Endothelial Cells; Endothelium, Vascular; Enzyme Induction; Mice; Mitochondria; Nitric Oxide Synthase Type III; Resveratrol; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; RNA, Small Interfering; Sirtuin 1; Sirtuins; Stilbenes

Oxidative stress plays an important role in type 2 diabetes-related endothelial dysfunction. We hypothesized that resveratrol protects against oxidative stress-induced endothelial dysfunction in aortas of diabetic mice by inhibiting tumor necrosis factor alpha (TNFalpha)-induced activation of NAD(P)H oxidase and preserving phosphorylation of endothelial nitric oxide synthase (eNOS).. We examined endothelial-dependent vasorelaxation to acetylcholine (ACh) in diabetic mice (Lepr(db)) and normal controls (m Lepr(db)). Relaxation to ACh was blunted in Lepr(db) compared with m Lepr(db), whereas endothelial-independent vasorelaxation to sodium nitroprusside (SNP) was comparable. Resveratrol improved ACh-induced vasorelaxation in Lepr(db) without affecting dilator response to SNP. Impaired relaxation to ACh in Lepr(db) was partially reversed by incubating the vessels with NAD(P)H oxidase inhibitor apocynin and a membrane-permeable superoxide dismutase mimetic TEMPOL. Dihydroethidium (DHE) staining showed an elevated superoxide (O(2)(.-)) production in Lepr(db), whereas both resveratrol and apocynin significantly reduced O(2)(.-) signal. Resveratrol increased nitrite/nitrate levels and eNOS (Ser1177) phosphorylation, and attenuated H(2)O(2) production and nitrotyrosine (N-Tyr) content in Lepr(db) aortas. Furthermore, resveratrol attenuated the mRNA and protein expression of TNFalpha. Genetic deletion of TNFalpha in diabetic mice (db(TNF-)/db(TNF-)) was associated with a reduced NAD(P)H oxidase activity and vascular O(2)(.-) production and an increased eNOS (Ser1177) phosphorylation, suggesting that TNFalpha plays a pivotal role in aortic dysfunction in diabetes by inducing oxidative stress and reducing NO bioavailability.. Resveratrol restored endothelial function in type 2 diabetes by inhibiting TNFalpha-induced activation of NAD(P)H oxidase and preserving eNOS phosphorylation, suggesting the potential for new treatment approaches to promote vascular health in metabolic diseases.

Topics: Animals; Aorta; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Endothelium, Vascular; Female; Gene Expression Regulation; Male; Mice; Mice, Inbred C57BL; NADPH Oxidases; Nitric Oxide; Nitric Oxide Synthase Type III; Oxidative Stress; Resveratrol; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Stilbenes; Tumor Necrosis Factor-alpha; Vasodilation; Vasodilator Agents

Resveratrol is a natural polyphenolic compound that activates nicotinamide adenosine dinucleotide-dependent deacetylase SIRT1. Resveratrol has recently been shown to exert potent antidiabetic actions when orally delivered to animal models of type 2 diabetes. However, the tissue(s) mediating these beneficial effects is unknown. Because SIRT1 is expressed in central nervous system (CNS) neurons known to control glucose and insulin homeostasis, we hypothesized that resveratrol antidiabetic effects are mediated by the brain. Here, we report that long-term intracerebroventricular infusion of resveratrol normalizes hyperglycemia and greatly improves hyperinsulinemia in diet-induced obese and diabetic mice. It is noteworthy that these effects are independent of changes in body weight, food intake, and circulating leptin levels. In addition, CNS resveratrol delivery improves hypothalamic nuclear factor-kappaB inflammatory signaling by reducing acetylated-RelA/p65 and total RelA/p65 protein contents, and inhibitor of nuclear factor-kappaB alpha and IkappaB kinase beta mRNA levels. Furthermore, this treatment leads to reduced hepatic phosphoenolpyruvate carboxykinase 1 mRNA and protein levels and ameliorates pyruvate-induced hyperglycemia in this mouse model of type 2 diabetes. Collectively, our results unveiled a previously unrecognized key role for the CNS in mediating the antidiabetic actions of resveratrol.

Topics: Animals; Antioxidants; Blotting, Western; Body Weight; Brain; Diabetes Mellitus, Type 2; Dietary Fats; Eating; Glucose; Homeostasis; Hyperglycemia; Liver; Male; Mice; Mice, Inbred C57BL; NF-kappa B; Protein Serine-Threonine Kinases; Resveratrol; Reverse Transcriptase Polymerase Chain Reaction; Sirtuin 1; Stilbenes

Resveratrol was reported to increase insulin sensitivity accompanied with the activation of AMP-activated protein kinase (AMPK), which is a key regulator of energy balance and an important drug target for type 2 diabetes. However, the effect of resveratrol structural analogs on AMPK activity and insulin sensitivity is still largely unknown. In this study, we analyzed the effect of several resveratrol structural analogs on AMPK activity in HepG2 cells, and combretastatin A-4 (CA-4) was identified as an activator of AMPK determined by its phosphorylation. AMPK activation was further confirmed by the phosphorylation of downstream acetyl-CoA carboxylase (ACC) and the decrease of upstream ATP level. Further investigation showed that CA-4 activates PPAR transcriptional activity in vitro with the luciferase reporter assay. In addition, we showed that CA-4 activated AMPK and downregulated gluconeogenic enzyme mRNA levels in liver, and improved the fasting blood glucose level in diabetic db/db mice. These results suggested that resveratrol analogs, such as CA-4, can function similarly as resveratrol and may provide important tools for improving insulin sensitivity.

Topics: 3T3-L1 Cells; Acetyl-CoA Carboxylase; Adenosine Triphosphate; AMP-Activated Protein Kinases; Animals; Diabetes Mellitus, Type 2; Enzyme Activation; Glucose; Humans; Mice; Mice, Inbred C57BL; Multienzyme Complexes; Phosphorylation; Poly(ADP-ribose) Polymerases; Protein Serine-Threonine Kinases; Stilbenes

Calorie restriction extends lifespan and produces a metabolic profile desirable for treating diseases of ageing such as type 2 diabetes. SIRT1, an NAD+-dependent deacetylase, is a principal modulator of pathways downstream of calorie restriction that produce beneficial effects on glucose homeostasis and insulin sensitivity. Resveratrol, a polyphenolic SIRT1 activator, mimics the anti-ageing effects of calorie restriction in lower organisms and in mice fed a high-fat diet ameliorates insulin resistance, increases mitochondrial content, and prolongs survival. Here we describe the identification and characterization of small molecule activators of SIRT1 that are structurally unrelated to, and 1,000-fold more potent than, resveratrol. These compounds bind to the SIRT1 enzyme-peptide substrate complex at an allosteric site amino-terminal to the catalytic domain and lower the Michaelis constant for acetylated substrates. In diet-induced obese and genetically obese mice, these compounds improve insulin sensitivity, lower plasma glucose, and increase mitochondrial capacity. In Zucker fa/fa rats, hyperinsulinaemic-euglycaemic clamp studies demonstrate that SIRT1 activators improve whole-body glucose homeostasis and insulin sensitivity in adipose tissue, skeletal muscle and liver. Thus, SIRT1 activation is a promising new therapeutic approach for treating diseases of ageing such as type 2 diabetes.

Topics: Acetylation; Allosteric Site; Animals; Blood Glucose; Caloric Restriction; Catalytic Domain; Cell Line; Diabetes Mellitus, Type 2; Dietary Fats; Disease Models, Animal; Drosophila melanogaster; Heterocyclic Compounds, 4 or More Rings; Humans; Insulin; Male; Mice; Mitochondria; Rats; Rats, Sprague-Dawley; Rats, Zucker; Resveratrol; Sirtuin 1; Sirtuins; Stilbenes

Resveratrol increases life span in lower organisms by activating the NAD(+)-dependent histone deacetylase Sirt1. Studies by and now show that resveratrol promotes longevity and improves glucose homeostasis in mice by stimulating the Sirt1-mediated deacetylation of the transcriptional coactivator PGC-1alpha.

Topics: Acetylation; Administration, Oral; Aging; Animals; Diabetes Mellitus, Type 2; Energy Metabolism; Glucose; Homeostasis; Humans; Insulin; Longevity; Male; Mice; Obesity; Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; Resveratrol; Signal Transduction; Sirtuin 1; Sirtuins; Stilbenes; Trans-Activators; Transcription Factors

There is intriguing recent evidence that the beta subunit of the signalsome--IKKbeta, a crucial catalyst of NF-kappaB activation--is an obligate mediator of the disruption of insulin signaling induced by excessive exposure of tissues to free fatty acids and by hypertrophy of adipocytes. Thus, agents which safely inhibit or suppress the activation of IKKbeta may have utility for reversing insulin resistance syndrome and aiding control of type 2 diabetes. Two natural agents which can achieve this effect in vitro--and which may have clinical potential in this regard--are the polyphenols resveratrol and silibinin. To date, limited absorbability and/or rapid glucuronidation have prevented these agents from achieving full therapeutic utility, but, by administering these agents in optimally absorbable forms, and co-administering inhibitors of glucuronidation such as probenecid, it may prove feasible to make these agents more clinically viable. Oral silibinin, in the guise of the milk thistle extract silymarin, already has documented clinical utility in a range of hepatic disorders, and recent evidence that dietary silibinin can inhibit the growth of certain cancers in rodents suggests that this agent may indeed have clinical potential as an IKKbeta inhibitor. A report that silymarin has a favorable impact on glycemic and lipidemic control in type 2 diabetics with cirrhosis, may or may not be indicative of IKKbeta inhibition in skeletal muscle and adipocytes. In light of the fact that IKKbeta plays a crucial role, not only in the induction of insulin resistance, but also atherogenesis, a host of inflammatory disorders, and the survival and spread of cancer, the development of pharmaceutical agents that could safely and feasibly achieve a down-regulation of IKKbeta activity would have broad therapeutic and preventive implications.

Topics: Adipocytes; Diabetes Mellitus, Type 2; Fatty Acids, Nonesterified; Flavonoids; Humans; I-kappa B Kinase; Insulin Resistance; Models, Biological; Phenols; Polyphenols; Probenecid; Protein Serine-Threonine Kinases; Resveratrol; Silybin; Silymarin; Stilbenes