Molecular docking analysis of beta-catenin with compounds derived from Lycopersicon esculentum

Beta-catenin is linked with colorectal cancer (CRC). Therefore, it is of interest to design and develop novel compounds to combat CRC. Hence, we document compounds (chlorogenic acid, gallic acid, protocatechuic acid, quercetin and vanillic acid) from Lycopersicon esculentum with optimal binding features for further consideration.     

Molecular docking analysis of beta-caryophyllene with IRS-1, cSrc and Akt

Diabetes mellitus (DM) is a common metabolic illness defined by hyperglycemia caused by insufficient production or absent of pancreatic insulin, with or without concomitant insulin action impairment. Hence, novel problem-solving approaches for assessing early metabolic diseases, notably insulin resistance, are urgently needed. Screening of natural compounds for drug discovery to combat diabetes is common in modern medical research and development. Therefore, it is of interest to document the molecular docking analysis data of beta-Caryophyllene, a naturally occurring sequiterpene with the downstream insulin signaling molecules such as IRS-1, cSrc and Akt for the management of type-2 diabetes. The molecular docking analysis data of beta-caryophyllene with the insulin downstream signaling molecules such as IRS-1, cSrc and Akt reveals its ability and further studies are needed to elucidate its complete mechanism of action against type-2 diabetes.     

Effect of β-Caryophyllene on insulin resistance in skeletal muscle of high fat diet and fructose-induced type-2 diabetic rats

High fat diet feeding results in hyperglycemia and insulin resistance, which is a major pathological feature of type-2 diabetes mellitus. The use of oral hypoglycaemic drugs is limited due to its deleterious side effects and there is a need to find more efficacious agents for diabetes management. Hence, it is of interest to show the mechanism of action of β-Caryophyllene on insulin signalling molecules in gastrocnemius muscle of high fat diet - induced type-2 diabetic rats. An oral effective dose of with β-Caryophyllene (200 mg/kg b.wt) was given for 30 days to high fat diet (comprising 2% cholesterol, 1% cholic acid, 30% coconut oil, 67% conventional rat feed) and fructose fed type-2 diabetic rats to find out whether β-Caryophyllene regulates IRS-1/Akt pathway of insulin signalling. The data shows that, β-Caryophyllene treatment significantly increased the mRNA and protein expression of insulin receptor (IR) in diabetic rats whereas there is no significant difference in mRNA expression of insulin receptor-substrate-1 (IRS-1) was observed among groups. The Akt mRNAand GLUT-4mRNA and protein level were also improved in gastrocnemius muscle of type-2 diabetic rats. Thus, we concluded that β-Caryophyllene could be used as potential phyto medicine for type-2 diabetes management.     

GPRC5B a putative glutamate-receptor candidate is negative modulator of insulin secretion

GPRC5B is an orphan receptor belonging to the group C family of G protein-coupled receptors (GPCRs). GPRC5B is abundantly expressed in both human and mouse pancreatic islets, and both GPRC5B mRNA and protein are up-regulated 2.5-fold in islets from organ donors with type 2 diabetes. Expression of Gprc5b is 50% lower in islets isolated from newborn (<3 weeks) than in adult (>36 weeks) mice. Lentiviral shRNA-mediated down-regulation of Gprc5b in intact islets from 12 to 16 week-old mice strongly (2.5-fold) increased basal (1 mmol/l) and moderately (40%) potentiated glucose (20 mmol/l) stimulated insulin secretion and also enhanced the potentiating effect of glutamate on insulin secretion. Down-regulation of Gprc5b protected murine insulin-secreting clonal MIN6 cells against cytokine-induced apoptosis. We propose that increased expression of GPRC5B contributes to the reduced insulin secretion and β-cell viability observed in type-2 diabetes. Thus, pharmacological targeting of GPRC5B might provide a novel means therapy for the treatment and prevention of type-2 diabetes.     

Oral administration of RAC-alpha-lipoic acid modulates insulin sensitivity in patients with type-2 diabetes mellitus: a placebo-controlled pilot trial.

Alpha-lipoic acid (ALA), a naturally occuring compound and a radical scavenger was shown to enhance glucose transport and utilization in different experimental and animal models. Clinical studies described an increase of insulin sensitivity after acute and short-term (10 d) parenteral administration of ALA. The effects of a 4-week oral treatment with alpha-lipoic acid were evaluated in a placebo-controlled, multicenter pilot study to determine see whether oral treatment also improves insulin sensitivity. Seventy-four patients with type-2 diabetes were randomized to either placebo (n = 19); or active treatment in various doses of 600 mg once daily (n = 19), twice daily (1200 mg; n = 18), or thrice daily (1800 mg; n = 18) alpha-lipoic acid. An isoglycemic glucose-clamp was done on days 0 (pre) and 29 (post). In this explorative study, analysis was done according to the number of subjects showing an improvement of insulin sensitivity after treatment. Furthermore, the effects of active vs. placebo treatment on insulin sensitivity was compared. All four groups were comparable and had a similar degree of hyperglycemia and insulin sensitivity at baseline. When compared to placebo, significantly more subjects had an increase in insulin-stimulated glucose disposal (MCR) after ALA treatment in each group. As there was no dose effect seen in the three different alpha-lipoic acid groups, all subjects receiving ALA were combined in the "active" group and then compared to placebo. This revealed significantly different changes in MCR after treatment (+27% vs. placebo; p < .01). This placebo-controlled explorative study confirms previous observations of an increase of insulin sensitivity in type-2 diabetes after acute and chronic intravenous administration of ALA. The results suggest that oral administration of alpha-lipoic acid can improve insulin sensitivity in patients with type-2 diabetes. The encouraging findings of this pilot trial need to be substantiated by further investigations.     

Insilico docking study of compounds elucidated from helicteres isora fruits with ampkinase- insulin receptor

Insulin receptor (IR) proteins were essential intracellular signaling peptides in the insulin action cascade. Insulin receptor substrate proteins (IRS-1and IRS-2) serve and regulate the insulin level in the normal insulin action. The broad role of IRS-1 and IRS-2 in cell growth and survival reveals a common regulatory pathway linking development, somatic growth, fertility, neuronal proliferation, and aging to the core mechanisms used by vertebrates for nutrient sensing. Such type of proteins were cyclic adenosine monophosphate-activated protein kinase, this proteins play a key role in the insulin response and regulation. Type -2 Diabetes mellitus occurs during prolonged periods of peripheral insulin resistance due to inactivation of IRS proteins. The compounds isolated from the medicinal plants were safer than synthetic drugs and possess high bio activity. In the present study, four compounds were elucidated from fruits of Helicteres isora. The elucidated compounds were evaluated for the antidiabetic activity using in silico docking study. The receptor was analyzed for the active site and pocket finder tools. The aminoacids such as Phenylalanine, Lysine, Glutamic acid and Asparigine were predicted as active site binding residues. Docking studies were done through Autodock 4 software. All the compounds from fruits of Helicteres isora showed good docking profiles with AMP Kinase, except compound-3 (1,2,3,4-tetrahydro-1,5,6,8-tetramethyl-7-(2-methylprop-1-enylnaphthalene-4-ylpivalate). Finally the result from the study demonstrates that the HS-1, HS-2 and HS-4 posses potent anti diabetic activity against type-2 diabetes mellitus through drug action on AMP kinase cascade system.     

Fatty acid transport across the cell membrane: Regulation by fatty acid transporters

Transport of long-chain fatty acids across the cell membrane has long been thought to occur by passive diffusion. However, in recent years there has been a fundamental shift in understanding, and it is now generally recognized that fatty acids cross the cell membrane via a protein-mediated mechanism. Membrane-associated fatty acid-binding proteins (‘fatty acid transporters’) not only facilitate but also regulate cellular fatty acid uptake, for instance through their inducible rapid (and reversible) translocation from intracellular storage pools to the cell membrane. A number of fatty acid transporters have been identified, including CD36, plasma membrane-associated fatty acid-binding protein (FABP_pm), and a family of fatty acid transport proteins (FATP1–6). Fatty acid transporters are also implicated in metabolic disease, such as insulin resistance and type-2 diabetes. In this report we briefly review current understanding of the mechanism of transmembrane fatty acid transport, and the function of fatty acid transporters in healthy cardiac and skeletal muscle, and in insulin resistance/type-2 diabetes. Fatty acid transporters hold promise as a future target to rectify lipid fluxes in the body and regain metabolic homeostasis.     

Novel aspects of adipocyte-induced skeletal muscle insulin resistance

Insulin resistance in skeletal muscle is an early event in the development of diabetes with obesity being one of the major contributing factors. Conditioned medium (CM) from differentiated human adipocytes impairs insulin signalling in human skeletal muscle cells. Recent data on adipocyte-induced insulin resistance in skeletal muscle cells describes underlying mechanisms of this process. Skeletal muscle insulin resistance involves multiple pathways and irreversible changes in the expression level of critical proteins. Furthermore, the reversibility of insulin resistance could be demonstrated. Several strategies to combat insulin resistance have been developed. One recent approach to treat obesity and the metabolic syndrome is the use of endocannabinoid receptor antagonists such as rimonabant. These compounds might also reduce insulin resistance in type 2 diabetes with effects on adipose tissue and liver and possibly skeletal muscle.     

Long-term wheel-running and acute 6-h advances alter glucose tolerance and insulin levels in TALLYHO/JngJ mice

Studies have shown a relationship between circadian rhythm disruptions and type-2 diabetes. This investigation examined the effects of circadian disruption (6-h phase advances) on the progression of diabetes in a type-2 diabetic mouse model –TALLYHO/JngJ – and whether wheel-running can alleviate the effects of the phase advances. 6-h advances alter fasting glucose, glucose tolerance and insulin production. Wheel-running reduced body mass, improved glucose tolerance and reduced insulin in TALLYHO/JngJ and alleviated some of the changes in diabetic symptoms due to 6-h advances. These results indicate that individuals with type-2 diabetes can benefit from physical activity and exercise can be a countermeasure to offset the effects of an acute phase advance.     

Current status of the E23K Kir6.2 polymorphism: implications for type-2 diabetes

The ATP-sensitive potassium (K_ATP) channel couples membrane excitability to cellular metabolism and is a critical mediator in the process of glucose-stimulated insulin secretion. Increasing numbers of K_ATP channel polymorphisms are being described and linked to altered insulin secretion indicating that genes encoding this ion channel could be susceptibility markers for type-2 diabetes. Genetic variation of K_ATP channels may result in altered -cell electrical activity, glucose homeostasis, and increased susceptibility to type-2 diabetes. Of particular interest is the Kir6.2 E23K polymorphism, which is linked to increased susceptibility to type-2 diabetes in Caucasian populations and may also be associated with weight gain and obesity, both of which are major diabetes risk factors. This association highlights the potential contribution of both genetic and environmental factors to the development and progression of type-2 diabetes. In addition, the common occurrence of the E23K polymorphism in Caucasian populations may have conferred an evolutionary advantage to our ancestors. This review will summarize the current status of the association of K_ATP channel polymorphisms with type-2 diabetes, focusing on the possible mechanisms by which these polymorphisms alter glucose homeostasis and offering insights into possible evolutionary pressures that may have contributed to the high prevalence of K_ATP channel polymorphisms in the Caucasian population.This work was supported by funding from the Canadian Diabetes Association (CDA) in honor of Gordon M. Stevenson, the Alberta Heritage Foundation for Medical Research (AHFMR), and the Canadian Institutes of Health Research (CIHR). M.J.R. is supported by AHFMR and CDA Scholarships. P.E.L. received salary support as an AHFMR Scholar and CIHR New Investigator     

Photocontrol of in vitro bud differentiation in Saintpaulia ionantha leaves and Lycopersicon esculentum cotyledons

The regeneration of buds from leaves of Saintpaulia ionantha Wendl cv. Sona and from cotyledons of Lycopersicon esculentum Mill. cv. UC 105 was studied in response to continuous light and daily light pulses. The regeneration of buds from cotyledons of Lycopersicon esculentum is high under continuous red and white light. Trie effect of light may be related to phytochrome. In Saintpaulia ionantha blue light appears to be very effective. The experimental results suggest that the blue light effects involve both a blue light absorbing photoreceptor and phytochrome     

Galactolipase activity and free fatty acid levels in chloroplasts of domestic and wild tomatoes with different chilling tolerance

In order to establish differences in the chilling sensitivity of domestic and wild Lycopersicon species, galactolipase (EC 3.1.1.26) activity, free fatty acid (FFA) level and Hill reaction activity were measured in chloroplasts isolated from control and cold treated leaves of L. esculentum Mill., cv. Norton, L. hirsutum Humb. and Bonpl., L. peruvianum var. glandulosum Mill. Galactolipase activity was higher in chloroplasts from Lycopersicon species with high chilling sensitivity than in chloroplasts of more chilling-resistant ones. A similar relationship was observed for FFA level in chloroplasts from both cold-stored and control leaves. Decrease in Hill reaction activity due to cold stress was greater in chloroplasts of more chilling-sensitive species. The changes are accompanied by a decline of photochemical activity. Considering the changes in the three parameters noted above, an increasing order of chilling tolerance was established: L. esculentum < L. hirsutum (700 m) < L. hirsutum (3100 m) < L. peruvianum (3400 m). It is suggested that measurements of galactolipase activity and FFA may be useful in an evaluation of differences in resistance to chilling injury of closely related species.     

Ursodeoxycholic Acid Ameliorates Fructose-Induced Metabolic Syndrome in Rats

The metabolic syndrome (MS) is characterized by insulin resistance, dyslipidemia and hypertension. It is associated with increased risk of cardiovascular diseases and type-2 diabetes. Consumption of fructose is linked to increased prevalence of MS. Ursodeoxycholic acid (UDCA) is a steroid bile acid with antioxidant, anti-inflammatory activities and has been shown to improve insulin resistance. The current study aims to investigate the effect of UDCA (150 mg/kg) on MS induced in rats by fructose administration (10%) in drinking water for 12 weeks. The effects of UDCA were compared to fenofibrate (100 mg/kg), an agonist of PPAR-α receptors. Treatment with UDCA or fenofibrate started from the 6^th week after fructose administration once daily. Fructose administration resulted in significant increase in body weight, elevations of blood glucose, serum insulin, cholesterol, triglycerides, advanced glycation end products (AGEs), uric acid levels, insulin resistance index and blood pressure compared to control rats. Moreover, fructose increased oxidative stress in aortic tissues indicated by significant increases of malondialdehyde (MDA), expression of iNOS and reduction of reduced glutathione (GSH) content. These disturbances were associated with decreased eNOS expression, increased infiltration of leukocytes and loss of aortic vascular elasticity. Treatment with UDCA successfully ameliorated the deleterious effects of fructose. The protective effect of UDCA could be attributed to its ability to decrease uric acid level, improve insulin resistance and diminish oxidative stress in vascular tissues. These results might support possible clinical application of UDCA in MS patients especially those present with liver diseases, taking into account its tolerability and safety. However, further investigations on human subjects are needed before the clinical application of UDCA for this indication.     

Antidiabetic activity of a xanthone compound, mangiferin

Mangiferin (MF) isolated from Anemarrhena asphodeloides Bunge rhizome, was tested for antidiabetic activity in KK-Ay mice, an animal model of type-2 diabetes. MF lowered the blood glucose level of KK-Ay mice 3 weeks after oral administration (p < 0.01). However, no effect on the blood glucose level in normal mice was seen, indicating that MF could be useful in treating type-2 diabetes. In addition, MF improved hyperinsulinemia and, on insulin tolerance test, reduced blood glucose levels of KK-Ay mice. From these findings, it seems likely that MF exerts its antidiabetic activity by decreasing insulin resistance.     

Mechanisms of endothelial dysfunction with development of type 1 diabetes mellitus: role of insulin and C-peptide

Complications associated with insulin-dependent diabetes mellitus (type-1diabetes) primarily represent vascular dysfunction that has its origin in the endothelium. While many of the vascular changes are more accountable in the late stages of type-1diabetes, changes that occur in the early or initial functional stages of this disease may precipitate these later complications. The early stages of type-1diabetes are characterized by a diminished production of both insulin and C-peptide with a significant hyperglycemia. During the last decade numerous speculations and theories have been developed to try to explain the mechanisms responsible for the selective changes in vascular reactivity and/or tone and the vascular permeability changes that characterize the development of type-1diabetes. Much of this research has suggested that hyperglycemia and/or the lack of insulin may mediate the observed functional changes in both endothelial cells and vascular smooth muscle. Recent studies suggest several possible mechanisms that might be involved in the observed decreases in vascular nitric oxide (NO) availability with the development of type-1 diabetes. In addition more recent studies have indicated a direct role for both endogenous insulin and C-peptide in the amelioration of the observed endothelial dysfunction. These results suggest a synergistic action between insulin and C-peptide that facilitates increase NO availability and may suggest new clinical treatment modalities for type-1 diabetes mellitus.     

Anti-Insulin Immune Responses Are Detectable in Dogs with Spontaneous Diabetes

Diabetes mellitus occurs spontaneously in dogs. Although canine diabetes shares many features with human type-1 diabetes, there are differences that have cast doubt on the immunologic origin of the canine disease. In this study, we examined whether peripheral immune responses directed against islet antigens were present in dogs with diabetes. Routine diagnostics were used to confirm diabetic status, and serum samples from dogs with (N = 15) and without (N = 15) diabetes were analyzed for the presence of antibodies against islet antigens (insulin, glutamic acid decarboxylase, insulinoma-associated protein tyrosine phosphatase, and islet beta-cell zinc cation efflux transporter) using standard radioassays. Interferon-γ production from peripheral blood T cells stimulated by porcine insulin and by human insulin was tested using Elispot assays. Anti-insulin antibodies were detectable in a subset of diabetic dogs receiving insulin therapy. Pre-activated T cells and incipient insulin-reactive T cells in response to porcine or human insulin were identified in non-diabetic dogs and in dogs with diabetes. The data show that humoral and cellular anti-insulin immune responses are detectable in dogs with diabetes. This in turn provides support for the potential to ethically use dogs with diabetes to study the therapeutic potential of antigen-specific tolerance.     

Quantitative Measurement of GLUT4 Translocation to the Plasma Membrane by Flow Cytometry

Glucose is the main source of energy for the body, requiring constant regulation of its blood concentration. Insulin release by the pancreas induces glucose uptake by insulin-sensitive tissues, most notably the brain, skeletal muscle, and adipocytes. Patients suffering from type-2 diabetes and/or obesity often develop insulin resistance and are unable to control their glucose homeostasis. New insights into the mechanisms of insulin resistance may provide new treatment strategies for type-2 diabetes.The GLUT family of glucose transporters consists of thirteen members distributed on different tissues throughout the body¹. Glucose transporter type 4 (GLUT4) is the major transporter that mediates glucose uptake by insulin sensitive tissues, such as the skeletal muscle. Upon binding of insulin to its receptor, vesicles containing GLUT4 translocate from the cytoplasm to the plasma membrane, inducing glucose uptake. Reduced GLUT4 translocation is one of the causes of insulin resistance in type-2 diabetes^2,3.The translocation of GLUT4 from the cytoplasm to the plasma membrane can be visualized by immunocytochemistry, using fluorophore-conjugated GLUT4-specific antibodies.Here, we describe a technique to quantify total amounts of GLUT4 translocation to the plasma membrane of cells during a chosen duration, using flow cytometry. This protocol is rapid (less than 4 hours, including incubation with insulin) and allows the analysis of as few as 3,000 cells or as many as 1 million cells per condition in a single experiment. It relies on anti-GLUT4 antibodies directed to an external epitope of the transporter that bind to it as soon as it is exposed to the extracellular medium after translocation to the plasma membrane.