Increasing effect of Tangzhiqing formula on IRS-1-dependent PI3K/AKT signaling in muscle

Antidiabetic activity of eupafolin through peroxisome proliferator-activated receptor-gamma and PI3K/Akt signaling in Type 2 diabetic rats

Eupafolin is a phyto compound of flavone that exerts anti-inflammatory, antioxidant, and antiproliferative properties. The main purpose of this study is to examine the antidiabetic effect of eupafolin on nicotinamide-streptozotocin (STZ)-induced Type 2 diabetes (T2D) rats. After nicotinamide (120 mg/kg) treatment, STZ (60 mg/kg) was administrated intravenously to induce T2D. Rats with fasting blood glucose (FBG) > 200 mg/dL are chosen for the study 7 days after T2D induction. The eupafolin treatment was continued for another 15 days. FBG and an oral glucose tolerance test (OGTT) were measured on the 21st day after T2D induction. The blood lipid, serum insulin, and homeostatic model assessment (HOMA-IR) were determined. In liver homogenate, oxidative stress indicators were measured. In addition, the effect of eupafolin on the expression of the proteins InsR, insulin receptor substrate (IRS)-2, GLUT4, PPARγ, and phosphatidylinositol 3-kinase (PI3K)/Akt was investigated using a western blot. As measured by OGTT and HOMA-IR, eupafolin treatment reduced FBG and insulin resistance (IR). Furthermore, when compared to diabetic rats, liver antioxidant enzymes were dramatically normalized. The level of glycogen in the liver of diabetic rats was increased by eupafolin treatment. In T2D rats, eupafolin dramatically increased the InsR, IRS-2, GLUT4, and PPARγ. Further, the eupafolin treatment activated the PI3K/Akt signaling in T2D rats. These findings imply that the antidiabetic mechanism of eupafolin may be related to the activation of the PPARγ and the PI3K/Akt signaling pathway in T2D rats. As a result, the flavonoid eupafolin could be an antidiabetic medication for T2D after a comprehensive clinical investigation.

Simultaneous Separation and Determination of Nine Active Ingredients in Sanyetangzhiqing by Cyclodextrin-Modified Micellar Electrokinetic Capillary Electrophoresis-Diode Array Detector

A simple and sensitive strategy using cyclodextrin-modified micellar electrokinetic chromatography with diode array detector was developed and applied for the simultaneous separation and determination of nine components in Sanyetangzhiqing (SYTZQ), a hypoglycemic and hypolipidemic agent. Several important parameters affecting separation performance were evaluated and optimized using single variable methods. Under the optimal conditions, baseline separation of the nine components, including four flavonoids (hyperoside, isoquercitrin, quercetin-3-O-glucuronoside, and astragalin), four phenolic acids (chlorogenic acid, rosmarinic acid, salvianolic acid B, and lithospermic acid), and a monoterpenoids (paeoniflorin), were achieved in less than 16 min. The correlation coefficients of the calibration curves were over 0.9996 for all the analytes. Intraday and interday precisions ranged from 0.4% to 4.8% and 1.7% to 5.0%, respectively. Recoveries of analytes varied from 95.3% to 105%. Validation results as well as the application to analyse SYTZQ samples demonstrated the applicability of the proposed method and thus provided an effective tool for the quality control of SYTZQ. Moreover, with the advantages of short time consuming, low energy consumption, high efficiency, and low cost, this method has laid a foundation for the determination and quality evaluation of multicomponents in Chinese herbal compounds.

Effect and mechanism of Tangzhiqing in improving cardiac function in mice with hyperlipidaemia complicated with myocardial ischaemia

Purpose

Tangzhiqing formula (TZQ) is a traditional Chinese medicine prescribed to treat lipid metabolism disorders, atherosclerosis, diabetes and diabetic cardiomyopathy. However, some challenges and hurdles remain. TZQ showed promising results in treating diabetes and hyperlipidaemia. However, its effect on and mechanism of action in hyperlipidaemia complicated with myocardial ischaemia (HL-MI) remain unknown.

Methods

In this study, a network pharmacology-based strategy integrating target prediction was adopted to predict the targets of TZQ relevant to the treatment of HL-MI and to further explore the involved pharmacological mechanisms.

Results

A total of 104 potential therapeutic targets were obtained, including MMP9, Bcl-2, and Bax, which may be related to the apoptosis and PI3K/AKT signalling pathways. Then, we confirmed these potential targets and pathways with animal experimentation. TZQ reduced lipid levels, increased the expression levels of Bcl-2, decreased Bax, caspase-3 and caspase-9 expression levels, and activated the PI3K/AKT signalling pathway.

Conclusion

In conclusion, this study provides new insights into the protective mechanisms of TZQ against HL-MI through network pharmacology and pharmacological approaches.

Sanye Tablet Ameliorates Insulin Resistance and Dysregulated Lipid Metabolism in High-Fat Diet-Induced Obese Mice

Sanye Tablet (SYT) is a patent prescription widely used in treating T2D and pre-diabetes, especially T2D comorbid with hypertriglyceridemia, for many years in China. However, the underlying mechanism that accounts for the anti-diabetic potential of SYT by regulating lipid-related intermediates remains to be elucidated. This study aimed to investigate the mechanism of SYT on lipid metabolism and insulin sensitivity in high-fat diet (HFD)-induced obese mice by means of combining lipidomics and proteomics. The obese mice models were developed via HFD feeding for 20 consecutive weeks. Mice in the treatment group were given metformin and SYT respectively, and the effects of SYT on body weight, blood glucose, insulin sensitivity, fat accumulation in the organs, and pathological changes in the liver were monitored. Lipid metabolism was examined by lipidomics. Further determination of signaling pathways was detected by proteomics. The biological contributions of the compounds detected in SYT’s chemical fingerprint were predicted by network pharmacology. SYT treatment reduced body weight, inhibited viscera and hepatic steatosis lipid accumulation, and prevented insulin resistance. Furthermore, it was found that circulatory inflammatory cytokines were reduced by SYT treatment. In addition, lipidomics analysis indicated that SYT targets lipid intermediates, including diacylglycerol (DAG) and Ceramide (Cer). Mechanistically, SYT positively affected these lipid intermediates by suppressing liver lipogenesis via downregulation of SREBP1/ACC and the JAK/STAT signaling pathway. Our results predicted that astragalin and rosmarinic acid might regulate the JAK-STAT pathway by targeting PIM2 and STAT1, respectively, while paeoniflorin and rosmarinic acid were likely to regulate inflammatory responses by targeting TNFα, IL-6, and IL-4 during T2D. Overall, our study provides supportive evidence for the mechanism of SYT’s therapeutic effect on dysregulated lipid metabolism in diabesity.

Bioactive flavonoids and stilbenes from the leaf of Morus alba var. multicaulis

Twenty-two flavonoids and stilbenes (1-22) were obtained from the leaf of Morus alba var. multicaulis. Among them, morusalbanosides A (1), B₁ (2), and B₂ (3) were new compounds. Moreover, compounds 1, 3, 4-11, 15-18, and 22 displayed inhibitory effects on triglyceride (TG) accumulation in HepG2 cells in a concentration dependent manner. Furthermore, compounds 1, 3, 11, and 22 could activate the phosphorylation of AMP-activated protein kinase α (AMPKα), reduce the synthesis of TG by inhibiting the expression of fatty acid synthase (FAS) and stearoyl-CoA desaturase 1 (SCD1). While, only compounds 1 and 11 could promote the phosphorylation of acetyl-CoA carboxylase 1 (ACC1) and accelerate the oxidation of fatty acids by up-regulating carnitine palmitoyltransferase 1A (CPT1A). In brief, this study found that most of the researched flavonoids and stilbenes could regulate TG metabolism in vitro. They might play the role by up-regulating phosphorylation of AMPKα, inhibiting TG biosynthesis, and promoting the oxidation of fatty acids.

Cassia Abbreviata Enhances Glucose Uptake and Glucose Transporter 4 Translocation in C2C12 Mouse Skeletal Muscle Cells

Background.

This study aim at assessing C. abbreviata aqueous extracts for its potential to exhibit anti-diabetic activity in skeletal muscle cells. In addition to the toxicological and glucose absorption studies, the action of C. abbreviata extracts on some major genes involved in the insulin signaling pathway was established.

Methods.

The in vitro cytotoxic effects C. abbreviata was evaluated on muscle cells using the MTT assay and the in vitro glucose uptake assay conducted using a modified glucose oxidase method described by Van de Venter et al. (2008). The amount of GLUT-4 on cell surfaces was estimated quantitatively using the flow cytometry technique. Real time quantitative PCR (RT-qPCR) was used to determine the expression of GLUT-4, IRS-1, PI3 K, Akt1, Akt2, PPAR-γ.

Results.

Cytotoxicity tests revealed that all extracts tested at various concentrations were non-toxic (LC₅₀ > 5000). Aqueous extracts of leaves, bark and seeds resulted in a dose-dependent increase in glucose absorption by cells, after 1 h, 3 h and 6 h incubation period. Extracts of all three plant parts had the best effect after 3 h incubation, with the leaf extract showing the best activity across time (Glucose uptake of 29%, 56% and 42% higher than untreated control cells after treatment with 1 mg/ml extract at 1 h, 3 h and 6 h, respectively). All extracts, with the exception 500 µg/ml seed extract, induced a two-fold increase in GLUT-4 translocation while marginally inducing GLUT-10 translocation in the muscle cells. The indirect immunofluorescence confirmed that GLUT-4 translocation indeed occurred. There was an increased expression of GLUT-4, IRS1 and PI3 K in cells treated with insulin and bark extract as determined by the RT-qPCR.

Conclusion.

The study reveals that glucose uptake involves GLUT-4 translocation through a mechanism that is likely to involve the upstream effectors of the PI3-K/Akt pathway.

Docking Studies on Potential Mechanisms for Decreasing Insulin Resistance by the Tangzhiqing Herbal Formula

Insulin resistance (IR) is considered as one of the principal pathways of type 2 diabetes mellitus pathogenesis and is associated with a series of abnormal signaling pathways. Tangzhiqing (TZQ) herbal formula is a well-known antidiabetic traditional Chinese medicine and has been used to treat type 2 diabetes mellitus and prediabetes for many years in China. We selected 13 natural products as representative compounds of the main active components in TZQ to investigate the interaction of these natural products with key signal proteins associated with IR using two different docking calculations. Salvianolic acids A and C (phenolic acids from Salvia miltiorrhiza), rutin (a flavonoid from Morus alba), paeoniflorin (a saponin from Paeonia lactiflora), and quercitrin (a flavonoid from Crataegus pinnatifida) showed great docking abilities towards multiple target proteins. These results have contributed to a clearer understanding regarding the regulation mechanism of TZQ on IR and have provided direction for further pharmacological studies.

Curcumin anti-diabetic effect mainly correlates with its anti-apoptotic actions and PI3K/Akt signal pathway regulation in the liver

This study aimed to investigate the therapeutic effect of curcumin on type 2 diabetes and its underlying mechanisms. A type 2 diabetes mellitus rat model was established by providing high-fat diet and low doses of streptozotocin. Type 2 diabetes mellitus rats were treated with low dose and high dose of curcumin for 8 weeks. The results showed that high-dose curcumin significantly reduced fasting blood glucose, total cholesterol, triglyceride, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, alanine aminotransferase, and aspartate transaminase, liver coefficient, and malondialdehyde levels, and BCL2-Associated X expression in the type 2 diabetes mellitus rats. High-dose curcumin increased the levels of liver superoxide dismutase, catalase, and glutathione; as well as the expression of liver B-cell lymphoma-2, phosphatidylinositol 3-kinase, phosphorylated phosphatidylinositol 3-kinase, protein kinase B, and phosphorylated protein kinase B in type 2 diabetes mellitus rats. Furthermore, it ameliorated the histological structure of the liver and pancreas in diabetes mellitus model rats. However, low-dose curcumin had no significant effect on diabetes mellitus model rats. The results suggest that adequate doses of curcumin controls type 2 diabetes mellitus development as well as the mechanism involved in its anti-apoptotic actions and phosphatidylinositol 3-hydroxy kinase/protein kinase B signal pathway regulation in the liver.

Regulation effects of rosemary (Rosmarinus officinalis Linn.) on hepatic lipid metabolism in OA induced NAFLD rats

Rosmarinus officinalis Linn. is a kind of medicinal and edible homologous plant, which is popular in the Mediterranean region with a significant effect on mind tranquilization, anti-oxidation, and metabolic improvement. However, the hypolipidemic effects and mechanism of rosemary ethanol extract (RO) and their metabolites are less known. In this study, the hypolipidemic effects of RO and its active compounds were clarified. The results showed that RO, rosmarinic acid (RA) and carnosic acid (CA) significantly reduced the contents of liver triglyceride (TG), total cholesterol (TC), free fatty acids (FFA) and improved cell hypertrophy, vacuolation, and cell necrosis in the liver of orotic acid induced non-alcoholic fatty liver disease (NAFLD) model rats. The mechanism and related pathways of RO and its main metabolites against lipid disorder were related to the up-regulation of the phosphorylation of adenosine 5'-monophosphate(AMP)-activated protein kinase (AMPK) and the inhibition of the sterol regulatory element binding protein-1c (SREBP-1c) cracking into the nucleus, following the down-regulation of fatty acid synthesis. In conclusion, our study demonstrates that RA and CA are active substances of RO, and provides scientific evidence to support functional food product development for improving NAFLD.

Metabolomics-Based Clinical Efficacy and Effect on the Endogenous Metabolites of Tangzhiqing Tablet, a Chinese Patent Medicine for Type 2 Diabetes Mellitus with Hypertriglyceridemia

Tangzhiqing tablet (TZQ) is derived from Tangzhiqing formula, which has been used to regulate glucose and lipid metabolism in China for hundreds of years. However, as a new Chinese patent medicine, its clinical indication is not clear. To explore the clinical indication and effect on the patients with type 2 diabetes mellitus (T2DM), a pilot clinical trial and metabolomics study were carried out. In the clinical study, T2DM patients were divided into three groups and treated with TZQ, placebo, or acarbose for 12 weeks, respectively. The metabolomic study based on UPLC Q-TOF MS was performed including patients with hypertriglyceridemia in TZQ and placebo groups and healthy volunteers. The clinical results showed that TZQ could reduce glycosylated hemoglobin (HbA1c) and fasting insulin. For patients with hypertriglyceridemia in TZQ group, the levels of HbA1c all decreased and were correlated with the baseline level of triglyceride. Metabonomics data showed a significant difference between patients and healthy volunteers, and 17 biomarkers were identified. After 12-week treatment with TZQ, 11 biomarkers decreased significantly (p<0.05), suggesting that TZQ could improve the metabolomic abnormalities in these participants. In conclusion, the clinical indication of TZQ was T2DM with hypertriglyceridemia, and its target was related to glycerophospholipid metabolism.

Mangiferin Improves Hepatic Lipid Metabolism Mainly Through Its Metabolite-Norathyriol by Modulating SIRT-1/AMPK/SREBP-1c Signaling

Objective: Mangiferin (MGF) is a natural xanthone, with regulation effect on lipid metabolism. However, the molecular mechanism remains unclear. We purposed after oral administration, MGF is converted to its active metabolite(s), which contributes to the effects on lipid metabolism. Methods: KK-A^y mice were used to validate the effects of MGF on lipid metabolic disorders. Liver biochemical indices and gene expressions were determined. MGF metabolites were isolated from MGF administrated rat urine. Mechanism studies were carried out using HepG2 cells treated by MGF and its metabolite with or without inhibitors or small interfering RNA (siRNA). Western blot and immunoprecipitation methods were used to determine the lipid metabolism related gene expression. AMP/ATP ratios were measured by HPLC. AMP-activated protein kinase (AMPK) activation were identified by homogeneous time resolved fluorescence (HTRF) assays. Results: MGF significantly decreased liver triglyceride and free fatty acid levels, increased sirtuin-1 (SIRT-1) and AMPK phosphorylation in KK-A^y mice. HTRF studies indicated that MGF and its metabolites were not direct AMPK activators. Norathyriol, one of MGF's metabolite, possess stronger regulating effect on hepatic lipid metabolism than MGF. The mechanism was mediated by activation of SIRT-1, liver kinase B1, and increasing the intracellular AMP level and AMP/ATP ratio, followed by AMPK phosphorylation, lead to increased phosphorylation level of sterol regulatory element-binding protein-1c. Conclusion: These results provided new insight into the molecular mechanisms of MGF in protecting against hepatic lipid metabolic disorders via regulating SIRT-1/AMPK pathway. Norathyriol showed potential therapeutic in treatment of non-alcoholic fatty liver disease.

Potential Hypoglycaemic and Antiobesity Effects of Senna italica Leaf Acetone Extract

Background

Type II diabetes is on the rise while obesity is one of the strongest risk factors of type II diabetes. The search for a drug for type II that can equally mitigate obesity related complication is desired.

Methods

The acetone leaf extract of Senna italica was evaluated for its cytotoxic, antiglycation, and lipolytic effect, glucose uptake, and GLUT4 translocation and expression using published methods, while that for adipogenesis and protein expression levels of obesity related adipokines was assessed using adipogenesis assay and mouse adipokine proteome profiler kit, respectively. The possible mechanism of glucose uptake was assessed through the inhibition of PI3K pathway.

Results

The extract had no adverse effect on 3T3-L1 cell viability (CC50 > 1000 μg/ml). High antiglycation effect was attained at 10 mg/ml, while at 25-200 μg/ml it showed no significant increase in adipogenesis and lipolysis. The extract at 100 μg/ml was shown to decrease the expression levels of various adipokines and minimal glucose uptake at 50-100 μg/ml with a nonsignificant antagonistic effect when used in combination with insulin. GLUT4 translocation and expression were attained at 50-100 μg/ml with an increase in GLUT4 expression when in combination with insulin.

Conclusion

The acetone leaf extract of S. italica stimulates glucose uptake through the PI3K-dependent pathway and can serve as a source of therapeutic agent for the downregulation of obesity-associated adipokines in obesity and antiglycation agents.

Natural products, an important resource for discovery of multitarget drugs and functional food for regulation of hepatic glucose metabolism

Imbalanced hepatic glucose homeostasis is one of the critical pathologic events in the development of metabolic syndromes (MSs). Therefore, regulation of imbalanced hepatic glucose homeostasis is important in drug development for MS treatment. In this review, we discuss the major targets that regulate hepatic glucose homeostasis in human physiologic and pathophysiologic processes, involving hepatic glucose uptake, glycolysis and glycogen synthesis, and summarize their changes in MSs. Recent literature suggests the necessity of multitarget drugs in the management of MS disorder for regulation of imbalanced glucose homeostasis in both experimental models and MS patients. Here, we highlight the potential bioactive compounds from natural products with medicinal or health care values, and focus on polypharmacologic and multitarget natural products with effects on various signaling pathways in hepatic glucose metabolism. This review shows the advantage and feasibility of discovering multicompound-multitarget drugs from natural products, and providing a new perspective of ways on drug and functional food development for MSs.

Rapid characterization of the absorbed chemical constituents of Tangzhiqing formula following oral administration using UHPLC-Q-TOF-MS

Tangzhiqing formula, a Chinese herbal formula, is used for the treatment of type II diabetes and prediabetes. Although its effectiveness has been certified by clinical use, its absorbed chemical constituents are not comprehensively represented. Thence, in order to reveal potential bioactive components and metabolism of Tangzhiqing formula, an ultra-high performance liquid chromatography with quadrupole time-of-flight mass spectrometry method was developed. A total of 86 absorbed components, including 38 prototype compounds and 48 metabolites, were identified in rat plasma, urine, and feces after oral administration of Tangzhiqing formula. This was the first systematic study on the chemical constituents and metabolic profiling of Tangzhiqing formula. The results indicated that alkaloids and flavonoids were main absorbed components, and glucuronidation and sulfation were the major metabolites. Moreover we concluded that alkaloids and flavonoids first underwent demethylation and hydrolysis reactions before biotransformed to phase II metabolites. This study provided valuable data for safety estimation of Tangzhiqing formula, which will be advantageous for clinical application.

Ginsenoside Rb1 improves cardiac function and remodeling in heart failure

We investigated the effect of ginsenoside Rb1 on cardiac function and remodeling in heart failure (HF). Four weeks after HF induction, the rats were administrated with ginsenoside Rb1 (35 and 70 mg/kg) and losartan (4.5 mg/kg) for 8 weeks. Losartan was used as a positive control. Cardiac function was assessed by measuring hemodynamic parameters. Histological changes were analyzed by HE and Masson’s trichrome staining. Cardiac hypertrophy, fibrosis, mitochondrial membrane potential and glucose transporter type 4 (GLUT4) levels were evaluated. In the present study, high dose of (H−) ginsenoside Rb1 decreased heart rate, improved cardiac function and alleviated histological changes induced by HF. H-ginsenoside Rb1 attenuated cardiac hypertrophy and myocardial fibrosis by decreasing left ventricular (LV) weight/heart weight ratio and cardiomyocyte cross-sectional area and reducing the levels of atrial natriuretic factor (ANF), β-myosin heavy chain (β-MHC), periostin, collagen I, Angiotensin II (Ang II), Angiotensin converting enzyme (ACE) and Ang II type 1 (AT1) receptor. Moreover, H-ginsenoside Rb1 decreased mitochondrial membrane potential and enhanced the translocation of GLUT4 to plasma membrane. The TGF-β1/Smad and ERK signaling pathways were inhibited and the Akt pathway was activated. These findings suggest that ginsenoside Rb1 might restore cardiac/mitochondrial function, increase glucose uptake and protect against cardiac remodeling via the TGF-β1/Smad, ERK and Akt signaling pathways.

Inhibitory Effects of Constituents from the Aerial Parts of Rosmarinus officinalis L. on Triglyceride Accumulation

Sixteen flavonoids (1-16) including two new ones, named officinoflavonosides A (1) and B (2) were obtained from the aerial parts of Rosmarinus officinalis. Among the known ones, 6, 10, and 13 were isolated from the rosmarinus genus for the first time. Their structures were elucidated by chemical and spectroscopic methods. Moreover, the effects on sodium oleate-induced triglyceride accumulation (TG) in HepG2 cells of the above-mentioned compounds and 16 other isolates (17-32) reported previously to have been obtained in the plant were analyzed. Results show that eight kinds of flavonoids (compounds 1, 2, 3, 6-9 and 11) and seven kinds of other known isolates (compounds 17-20, 23, 26 and 31) possessed significant inhibitory effects on intracellular TG content in HepG2 cells. Among them, the activities of compounds 1 and 20 were comparable to that of orlistat, which suggested that these compounds in this plant might be involved in lipid metabolism.

Anti-Diabetic Effects of Jiang Tang Xiao Ke Granule via PI3K/Akt Signalling Pathway in Type 2 Diabetes KKAy Mice

Jiang Tang Xiao Ke (JTXK) granule, a Chinese herbal formula, has been used clinically to treat type 2 diabetes (T2DM) for decades. Our previous studies showed that JTXK granule exhibited anti-diabetic and anti-oxidative functions in experimental diabetic rats induced by a high fat diet and streptozotocin. However, the underlying mechanisms remain poorly understood. Herein, we aimed to investigate the therapeutic effect of JTXK granule on T2DM KKAy mice and the possible associations with skeletal muscle in the current study. Our results showed that JTXK granule significantly reduced food intake and body weight in T2DM KKAy mice. JTXK granule treatment also decreased the blood glucose and HbA1c levels and increased the insulin sensitivity in a time-dependent manner. Additionally, it ameliorated hyperlipidaemia and induced a lower free fatty acid level, displaying an effect on disorders of lipid metabolism. JTXK granule significantly increased the expression of insulin receptor substrate-1 (IRS-1), phosphoinositide 3-kinase (PI3K), protein kinase B (PKB/Akt) and glucose transporter 4 (Glut4) and decreased the expression of glycogen synthase kinase 3β (GSK3β). We concluded that JTXK granule is an effective drug for T2DM through regulating the PI3K/Akt signalling pathway in skeletal muscle.

Mulberry anthocyanin extract regulates glucose metabolism by promotion of glycogen synthesis and reduction of gluconeogenesis in human HepG2 cells

Mulberry has been demonstrated to possess important biological activities such as antioxidation and antiinflammation. However, research on the ability of mulberry for diabetes improvement mainly focuses on the leaves and less on the fruit. This study showed that a mulberry anthocyanin extract (MAE) had a significant effect on increasing the glucose consumption in HepG2 cells. The MAE enhanced the glycogen content and suppressed levels of glucose production. The enzyme activities of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) were decreased in HepG2 cells after MAE treatment due to PPARγ coactivator 1α (PGC-1α) and forkhead box protein O1 (FOXO1) inhibition. Moreover, the phosphorylation of protein kinase B (AKT) and glycogen synthase kinase-3β (GSK-3β) was increased by the MAE, leading to an expression enhancement of glycogen synthase 2 (GYS2). And this effect was blocked by the phosphoinositide 3-kinase (PI3K) inhibitor LY294002. In summary, our results suggested that the MAE regulates glucose metabolism by activating the PI3K/AKT pathway that relates to glycogen synthesis as well as through the inhibition of key molecules that promote gluconeogenesis.

Mulberry anthocyanin extract ameliorates insulin resistance by regulating PI3K/AKT pathway in HepG2 cells and db/db mice

This study evaluated the capacity of mulberry anthocyanin extract (MAE) on insulin resistance amelioration in HepG2 cells induced by high glucose and palmitic acid and diabetes-related metabolic changes in type 2 diabetic mice. In vitro, MAE alleviated insulin resistance in HepG2 cells and increased glucose consumption, glucose uptake and glycogen content. Enzyme activities of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) were decreased due to PPARγ coactivator 1α (PGC-1α) and forkhead box protein O1 (FOXO1) inhibition. Furthermore, phosphorylation of protein kinase B (AKT) and glycogen synthase kinase-3β (GSK3β) in model cells was recovered after treated with MAE, leading to an up-regulation of glycogen synthase 2 (GYS2), and this effect was blocked by the phosphatidylinositol-3-kinase (PI3K) inhibitor LY294002. In vivo, MAE supplementation (50 and 125 mg/kg body weight per day) markedly decreased fasting blood glucose, serum insulin, leptin, triglyceride and cholesterol levels and increased adiponectin levels in db/db mice. The improvement of related metabolic parameters was in part associated with the impact of MAE on activating AKT and downstream targets in liver, skeletal muscle and adipose tissues. In summary, these findings suggest that MAEs have potential benefits on improving dysfunction in diabetic mice and mitigating insulin resistance in HepG2 cells via activation of PI3K/AKT pathways.

Erythropoietin and diabetes mellitus

Erythropoietin (EPO) is a 30.4 kDa growth factor and cytokine that governs cell proliferation, immune modulation, metabolic homeostasis, vascular function, and cytoprotection. EPO is under investigation for the treatment of variety of diseases, but appears especially suited for the treatment of disorders of metabolism that include diabetes mellitus (DM). DM and the complications of this disease impact a significant portion of the global population leading to disability and death with currently limited therapeutic options. In addition to its utility for the treatment of anemia, EPO can improve cardiac function, reduce fatigue, and improve cognition in patients with DM as well as regulate cellular energy metabolism, obesity, tissue repair and regeneration, apoptosis, and autophagy in experimental models of DM. Yet, EPO can have adverse effects that involve the vasculature system and unchecked cellular proliferation. Critical to the cytoprotective capacity and the potential for a positive clinical outcome with EPO are the control of signal transduction pathways that include protein kinase B, the mechanistic target of rapamycin, Wnt signaling, mammalian forkhead transcription factors of the O class, silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae), and AMP activated protein kinase. Therapeutic strategies that can specifically target and control EPO and its signaling pathways hold great promise for the development of new and effective clinical treatments for DM and the complications of this disorder.

FoxO Transcription Factors and Regenerative Pathways in Diabetes Mellitus

Mammalian forkhead transcription factors of the O class (FoxO) are exciting targets under consideration for the development of new clinical entities to treat metabolic disorders and diabetes mellitus (DM). DM, a disorder that currently affects greater than 350 million individuals globally, can become a devastating disease that leads to cellular injury through oxidative stress pathways and affects multiple systems of the body. FoxO proteins can regulate insulin signaling, gluconeogenesis, insulin resistance, immune cell migration, and cell senescence. FoxO proteins also control cell fate through oxidative stress and pathways of autophagy and apoptosis that either lead to tissue regeneration or cell demise. Furthermore, FoxO signaling can be dependent upon signal transduction pathways that include silent mating type information regulation 2 homolog 1 (S. cerevisiae) (SIRT1), Wnt, and Wnt1 inducible signaling pathway protein 1 (WISP1). Cellular metabolic pathways driven by FoxO proteins are complex, can lead to variable clinical outcomes, and require in-depth analysis of the epigenetic and post-translation protein modifications that drive FoxO protein activation and degradation.