Glucose Consumption In HepG2 Cells Research Articles

Effects of flavonoids-rich Chinese bayberry (Myrica rubra Sieb. et Zucc.) pulp extracts on glucose consumption in human HepG2 cells

Flavonoids composition of Chinese bayberry (Myrica rubra Sieb. et Zucc.) pulp extracts was characterized by LC-ESI-Q-TOF-MS and quantification of flavonoids in nine bayberry cultivars was carried out by HPLC. As a result, five flavonoids, i.e. cyanidin-3-O-glucoside (C-3-Glu), myricetin-3-O-rhamnoside (M-3-Rha), quercetin-3-O-galactoside (Q-3-Gal), quercetin-3-O-glucoside (Q-3-Glu), and quercetin-3-O-rhamnoside (Q-3-Rha) were identified and quantified. The glucose consumption activities of nine bayberry cultivars varied significantly among cultivars and they were well correlated with their total phenolics, total flavonoids contents, and DPPH scavenging activities. In addition, C-3-Glu and three quercetin-3-O-glycosides (Q-3-Glys, i.e. Q-3-Gal, Q-3-Glu, and Q-3-Rha), but not M-3-Rha, showed significant enhancement of glucose consumption in HepG2 cells. There were significant correlations between the glucose consumption activity with the contents of C-3-Glu and the sum of three Q-3-Glys, respectively. These results showed that bayberry cultivars with high content of C-3-Glu and Q-3-Glys may have great potential as hypoglycemic foods.

Tadehaginoside modulates lipogenesis and glucose consumption in HepG2 cells

Tadehaginoside (TS) is a phenylpropanoid glycoside found in Tadehagi triquetrum, a medicinal plant with multiple biological activities. This study investigated the effect of TS on lipogenesis and glucose consumption in HepG2 cells. Treatment with TS inhibited lipid accumulation in a dose-dependent manner. This inhibition was closely associated with the downregulation of lipogenic genes such as SREBP-1a, SREBP-2 and their downstream targets (FAS, ACC, HMGR) and the upregulation of lipolytic gene PPARα as revealed by real-time quantitative PCR. Further investigation showed that TS significantly stimulated glucose consumption by HepG2 cells and glucose uptake by C2C12 myotubes, which could be partially explained by the upregulation of PPARγ. Collectively, these results clearly indicate that TS is an effective regulator of lipogenesis and glucose consumption, which could be useful in treatment of obesity and diabetes.

γ‐Conglutin, the lupin seed glucose‐lowering glycoprotein, interferes on insulin pathway in Hep G2 cells (1045.16)

Gamma‐conglutin (γ‐C), a Lupinus albus, seed glycoprotein, has been shown to lower blood glucose in hyperglycaemic rats and increase glucose consumption in HepG2 cells. Aim of the present work was to assess the modalities of interaction of this protein with the target cells, so as to contribute unveiling its mechanism of action. γ‐Conglutin internalization: HepG2 cells, pretreated for 30’ w/wo inhibitors of caveolae mediated endocytosis [filipin (5 μg/ml) and genistein (200 μM)], clathrin‐mediated pathway [chlorpromazine (25 μM), methyl‐β‐cyclodextrin (5 mM)], and macropinocytosis [amiloride (5 mM)], were incubated with FICT‐γ‐conglutin (50 μg/ml) for 4 h at 37°C, followed by FACS analysis. The macropinocitosis pathway was the mechanism of γ‐conglutin internalization (69% inhibition). 2D‐electrophoresis of cell lysates and antibody reaction of the blotted maps showed that γ‐conglutin is internalized in intact form. Moreover, the protein is modified inside the cell by multiple phosphorylation. Insulin pathway: reduced effect on AMPK activity (‐50% vs controls) and increased expression of phosphorylated AKT form (+ 25% vs controls) were recorded in HepG2 cells, following western‐blot analysis, exposed to 10 mM γ‐conglutin and/or 100 nM insulin, or metformin 10 mM.Grant Funding Source: MIUR of Italy

Synthesis and Evaluation of Novel Oleanolic Acid Derivatives as Potential Antidiabetic Agents

Antidiabetic agents simultaneously inhibiting hepatic glucose production and stimulating hepatic glucose consumption could apply a better control over hyperglycemia. A series of oleanolic acid derivatives with bulky substituents at C-3 position were designed and synthesized in order to search for this kind of agents. All of the compounds were evaluated biologically in vitro using glycogen phosphorylase and HepG2 cells. The results indicated that several derivatives exhibited moderate-to-good inhibitory activities against glycogen phosphorylase. Compound 8g showed the best inhibition with an IC50 value of 5.4μm. Moreover, most of the derivatives were found to increase the glucose consumption in HepG2 cells in a dose-dependent manner. The possible binding mode of compound 8g with glycogen phosphorylase was also explored by docking study. 8g was found to have hydrogen bonding interactions with Arg193, Arg310, and Arg60 of the allosteric site.

Antihyperglycemic Glucosylated Coumaroyltyramine Derivatives from Teucrium viscidum

Eight new glucosylated coumaroyltyramine derivatives, teuvissides A-H (1-8), were isolated from whole plants of Teucrium viscidum. Their structures were elucidated using spectroscopic data and chemical methods. The antihyperglycemic activities of these compounds were evaluated in HepG2 cells and 3T3-L1 adipocytes, and all of the isolates elicited different levels of glucose consumption at a concentration of 2.0 μM. Teuvissides A (1), B (2), and F (6) induced 2.2-, 2.1-, and 2.2-fold changes, respectively, in the levels of glucose consumption in HepG2 cells and 2.5-, 2.1-, and 2.3-fold changes, respectively, in 3T3-L1 adipocytes relative to the basal levels.

Determination of anti-hyperglycaemic activity in steroidal glycoside rich fraction of lily bulbs and characterization of the chemical profiles by LC-Q-TOF-MS/MS

The bulbs of Lilium brownii Brown var. viridulum Baker (lily) are commonly known as “Bai-he” for both functional food and medicine in China. In this study, the combination of bio-assay guided fractionation and chemical analysis revealed that steroidal glycoside rich L. brownii fraction (SGL) exhibited potential anti-hyperglycaemic activity. Further investigations demonstrated that SGL could increase glucose consumption in HepG2 cells and 3T3-L1 adipocytes by 1.61- and 2.13-fold, respectively, and enhance 3T3-L1 preadipocyte differentiation. Total 29 steroidal glycosides in SGL were positively or tentatively identified using liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (LC-Q-TOF-MS/MS), which afforded us a comprehensive understanding of the bioactive fraction. These results suggested that steroidal glycosides in L. brownii possessed desirable potential in glucose metabolism and insulin sensitivity. This is the first report on the determination of anti-hyperglycaemic activity in steroidal glycoside rich fraction of lily bulbs and characterization of the chemical profiles by LC-Q-TOF-MS/MS.

Modulation of Lipogenesis and Glucose Consumption in HepG2 Cells and C2C12 Myotubes by Sophoricoside

Sophoricoside, an isoflavone glycoside isolated from Sophora japonica (Leguminosae), has been widely reported as an immunomodulator. In this study, the effects of sophoricoside on lipogenesis and glucose consumption in HepG2 cells and C2C12 myotubes were investigated. Treatment with sophoricoside at concentrations of 1–10 μM inhibited lipid accumulation in HepG2 cells in a dose-dependent manner. At the same concentration range, no effect on cell viability was observed in the MTT assay. Inhibition of lipogenesis was associated with the downregulation of SREBP-1a, SREBP-1c, SREBP-2 and their downstream target genes (FAS, ACC, HMGR) as revealed by realtime quantitative PCR. The lipid-lowering effect was mediated via the phosphorylation of AMPK. Further investigation of the activities of this isoflavone showed that sophoricoside has the capability to increase glucose uptake by C2C12 myotubes. It also effectively inhibited the activities of α-glucosidase and α-amylase in vitro and remarkably lowered postprandial hyperglycaemia in starch-loaded C57BL6/J mice. These results suggest that sophoricoside is an effective regulator of lipogenesis and glucose consumption and may find utility in the treatment of obesity and type 2 diabetes.

Antidiabetic effects of Swertia macrosperma extracts in diabetic rats

Ethnopharmacological relevanceSwertia macrosperma is a traditional folk medicine used for its anti-hepatitis, antipyretic and antidotal effects as “Dida” or “Zangyinchen” in Tibet, Yunnan and Guizhou province for a long time, and it has been reported for its anti-diabetic effects in a Chinese patent. Swertia macrosperma was reported rich in xanthones, iridoids, seco-iridoids and their glycosides, several of which had been documented as potential antidiabetic agents. The objective of this study was to investigate the antidiabetic effect of Swertia macrosperma in diabetic rats. Materials and methodsThis study was designed firstly to evaluate the effect of Swertia macrosperma on glucose consumption in HepG2 cells. Based on the result in HepG2 cells, the antidiabetic effect of ethanol extract (EE) and n-butanol extract (BE) were investigated in diabetic rats induced by high fat fed and streptozotocin. The effects of EE and BE on fasting blood glucose, oral glucose tolerance test, serum insulin, glycosylated hemoglobin, serum lipid level, serum antioxidant parameters, glucokinase, glucose-6-phosphatase activities and glycogen content in liver tissue were measured, histology examination of pancreatic tissue was also carried out. ResultsAfter 4 weeks treatment with EE and BE, apparently decreased fasting blood glucose concentrations were observed in these treated groups, compared with the diabetic control groups. Additionally, improvement in serum antioxidant parameters and lipid profile were evidenced clearly. Moreover, EE and BE had effects of protecting the pancreatic β-cells and stimulating insulin secretion from the remaining pancreatic β-cells, evidenced by pancreatic histology examination. Increased glucokinase activity and decreased glucose-6-phosphatase activity were observed in liver. ConclusionThe results of in vivo and in vitro experiment suggested that EE and BE of Swertia macrosperma had excellent effects on controlling the hyperglycemia and hyperlipidemia in diabetic rats.

Internalization of intact γ‐conglutin, the lupin seed glucoselowering glycoprotein, by Hep G2 cells: biochemical and microscopy studies

Gamma‐conglutin (γ‐C), a Lupinus albus seed glycoprotein, has been shown to lower blood glucose in hyperglycaemic rats and increase glucose consumption in HepG2 cells. Aim of the present work was to monitor the localization of this protein in HepG2 cells in parallel to the glucose uptake. HepG2 cells treated with γ‐C were processed to confocal microscopy and transmission electron microscopy (TEM): the protein was detected with specific antibodies. After 3 h treatment, γ‐C was accumulated inside the cells and at 6 h it was diffused as protein aggregates into the cytoplasm. At the same time, glucose uptake increases by 64% vs the control cells. At 24 h the intracellular staining was reduced and protein aggregates stacked onto the cell membranes were visible. TEM showed that microvilli were involved in trapping the protein at the beginning of the process. Microscopy observations were confirmed by 2D electrophoresis showing that the protein inside the cells consisted of its intact subunits. These findings, while confirming the remarkable glucose uptake capacity by HepG2 cells, showed that γ‐C is internalized by the cells, thus opening the way to new strategies for the understanding of the described lupin γ‐conglutin insulin‐mimetic activity.This work was partially supported by a grant of MIUR from Italy

Rosemary (Rosmarinus officinalisL.) Extract Regulates Glucose and Lipid Metabolism by Activating AMPK and PPAR Pathways in HepG2 Cells

An epidemic of metabolic disorders such as obesity and diabetes is rising dramatically. Using natural products as potential preventive and therapeutic interventions for these disorders has drawn worldwide attention. Rosemary has been shown to lower blood glucose and cholesterol levels and mitigate weight gain in several in vivo studies. However, the mechanisms are essentially unknown. We investigated the effects of rosemary extract on metabolism and demonstrated that rosemary extract significantly increased glucose consumption in HepG2 cells. The phosphorylation of AMP-activated protein kinase (AMPK) and its substrate, acetyl-CoA carboxylase (ACC), was increased by rosemary extract. Rosemary extract also transcriptionally regulated the genes involved in metabolism, including SIRT1, PPARγ coactivator 1α (PGC1α), glucose-6-phosphatase (G6Pase), ACC, and low-density lipoprotein receptor (LDLR). Furthermore, the PPARγ-specific antagonist GW9662 diminished rosemary's effects on glucose consumption. Overall, our study suggested that rosemary potentially increases liver glycolysis and fatty acid oxidation by activating AMPK and PPAR pathways.

A novel indole derivative compound GY3 improves glucose and lipid metabolism via activation of AMP-activated protein kinase pathway

The AMP-activated protein kinase (AMPK) is a ubiquitously expressed serine/threonine protein kinase that functions as an intracellular fuel sensor. It has been demonstrated to mediate the activities of a number of pharmacological and physiological factors that exert beneficial effects on type2 diabetes mellitus. GY3 is a novel synthesized indole compound derived from indomethacin, a non-steroid anti-inflammatory drug. In a previous study, we found that GY3 could improve insulin resistance and lower glucose levels in db/db mice, although its mechanism of action is not yet clear. In this study, we demonstrate that in vivo administration of GY3 improved serum triglyceride levels and decreased lipid accumulation in the livers of db/db mice. In vitro studies show that GY3 increased glucose consumption in HepG2 cells and 3T3-L1 adipocytes, decreased free fatty acid (FFA)-induced lipid accumulation in HepG2 cells and lipid accumulation in 3T3-L1 adipocytes. In vitro studies further show that GY3 improved glucose and lipid metabolism through an AMPK-dependent pathway but not the PI3K pathway. These findings suggest that GY3 is an effective agent for the improvement of glucose and lipid metabolism through AMPK pathway activation.

Synthesis and anti-hyperglycemic activity of hesperidin derivatives

A series of hesperidin derivatives were prepared and identified by IR, 1H NMR, and MS spectra. These compounds were evaluated in vitro and in vivo based on α-glucosidase inhibition, glucose consumption of HepG2 cells, and blood glucose level in streptozotocin-induced diabetic mice. The results revealed that all the compounds exhibited anti-hyperglycemic activities. The inhibition at 10−3M of compounds 3 and 7a on α-glucosidase were 55.02% and 53.34%, respectively, as compared to 54.80% by acarbose. Treated by compound 3 and the reference drug metformin, glucose consumption of HepG2 cell were 1.78 and 2.11mM, respectively. After the streptozotocin-induced diabetic mice were oral administrated with compound 3 at 100mgkg−1d−1 for 10days, the blood glucose level of 3 treated mice (13.23mM, P<0.05) showed significant difference when compared to model control (23.03mM). Thus, compound 3 exhibited promising anti-hyperglycemic activity.

Lupin seed γ-conglutin lowers blood glucose in hyperglycaemic rats and increases glucose consumption of HepG2 cells

The aim of the present study was to evaluate the effect of a chronic oral γ-conglutin treatment in male Sprague-Dawley rats in which hyperglycaemia had been induced by supplying 10% d-glucose in drinking-water. A γ-conglutin dosage of 28mg/kg body weight was daily administered to animals for 21d. Plasma glucose, insulin and glucose overloading were monitored. Chronic administration of glucose resulted in a statistically significant (P<0·05) increase in fasting blood glucose (2·5-fold) and insulin (2·7-fold) v. the values recorded in control rats. Simultaneous treatment with γ-conglutin attenuated the rise in plasma glucose (1·9-fold) and insulin (1·8-fold) levels in the glucose-fed rats (P<0·05). Fasting insulin and homeostasis model of insulin resistance were decreased by 34 and 48% (P<0·05), respectively, in the γ-conglutin-treated rats v. the values found in pair-fed animals. To confirm these results with a different approach, HepG2 cells, grown for 24 and 48h in Dulbecco's minimum essential medium containing different glucose concentrations (5·5, 11·1 and 16·5mmol/l), were exposed to 10μmol/l γ-conglutin with or without 10mmol/l metformin or 100nmol/l insulin. γ-Conglutin increased glucose consumption (from 1·5- to 2·5-fold) in HepG2 cells, under all experimental conditions; this effect was more evident after 48h incubation. Moreover, in this in vitro model, the addition of γ-conglutin potentiated the activity of insulin and metformin in cell glucose consumption. These findings extend the previous ones and suggest the potential use of lupin γ-conglutin in the control of glycaemia.

A novel agonist of PPAR-γ based on barbituric acid alleviates the development of non-alcoholic fatty liver disease by regulating adipocytokine expression and preventing insulin resistance

Non-alcoholic fatty liver disease (NAFLD) is a frequent kind of metabolic syndrome, which included a wide spectrum of liver damage and closely associated with insulin resistance and other metabolic syndromes such as obesity, type II diabetes, hyperglycemia, etc. Recently, a new series of PPARγ ligands based on barbituric acid has been designed, in which 5-(4-(benzyloxy)benzylidene)pyrimidine-2,4,6(1H,3H,5H)-trione (SKLB102) showed a high affinity with PPARγ. The current study aimed to evaluate the protective effect of SKLB102 on NAFLD and investigate the underlying mechanisms. In vivo, oral administration of SKLB102 prevented the pathological development, as demonstrated by reducing liver weight and visceral fat effectively, decreasing the serum levels of alanine transaminase, TNF-α and glucose, diminishing the hepatic triglyceride and malondialdehyde content and recovering the abnormal down-regulation of LDL. Histological examination of liver sections by Oil Red O and H&E staining confirmed the protective effect of SKLB102 on NAFLD. Furthermore, SKLB102 elevated the serum level of adiponectin, reduced the serum level of leptin and prevented insulin resistance. Western blots indicated that SKLB102 increased the hepatic AMPK activities and CPT-1 expression. In vitro, SKLB102 showed the ability of significantly enhancing adiponectin expression and inhibiting leptin expression in 3T3-L1 adipocytes. Furthermore, SKLB102 could promote glucose consumption in HepG2 cells in the presence of 0.1 μM insulin. In conclusion, our current study provided strong evidence that SKLB102 had potent ability to reduce fat deposition and protect liver against NAFLD through regulating adipocytokine expression and preventing insulin resistance, which might be of protective value for the prevention of NAFLD.

Genistein reverses free fatty acid-induced insulin resistance in HepG2 hepatocytes through targeting JNK

This study investigated the effects and molecular mechanisms of genistein in improving insulin resistance induced by free fatty acids (FFAs) in HepG2 hepatocytes. A model of insulin resistance in HepG2 cells was established by adding palmitic acid (0.5 mmol/L) to the culture medium and the cells were treated by genistein. Glucose consumption of HepG2 cells was determined by glucose oxidase method. The levels of c-jun N-terminal kinase (JNK) phosphorylation, insulin receptor substrate-1 (IRS-1) Ser307 phosphorylation, JNK, IRS-1, phosphatidylinositol-3-kinase p85 (PI-3K p85) and glucose transporter 1 (GLUT1) proteins were detected by Western blotting. The results showed that after the treatment with palmitic acid for 24 h, the insulin-stimulated glucose transport in HepG2 cells was inhibited, and the glucose consumption was substantially reduced. Meanwhile, the expressions of IRS-1, PI-3K p85 protein and GLUT1 were obviously reduced, while the levels of JNK phosphorylation and IRS-1 Ser307 phosphorylation and the expression of JNK protein were significantly increased, as compared with cells of normal control. However, the aforementioned indices, which indicated the existence of insulin resistance, were reversed by genistein at 1-4 μmol/L in a dose-dependent manner. It was concluded that insulin resistance induced by FFAs in HepG2 hepatocytes could be improved by genistein. Genistein might reverse FFAs-induced insulin resistance in HepG2 cells by targeting JNK.

Furoxan nitric oxide donor coupled chrysin derivatives: Synthesis and vasculoprotection

A series of furoxan-based nitric oxide-releasing chrysin derivatives were synthesized. Pharmacological assays indicated that all chrysin derivatives exhibited in vitro inhibitory activities against aldose reductase and advanced glycation end-product formation. Some chrysin derivatives were also found to increase the glucose consumption of HepG2 cells. Furthermore, the compounds released a low amount of NO in the presence of L-cysteine (range from 0.20% to 1.89%). These hybrid furoxan-based NO donor chrysin derivatives offer a mutual prodrug design concept for the development of therapeutic or preventive agents for vascular complications due to diabetes.

Synthesis, characterization and vasculoprotective effects of nitric oxide-donating derivatives of chrysin

Vascular complications are major causes of disability and death in patients with diabetes mellitus. It is often characterized by endothelial dysfunction. Studies have shown that either the loss of nitric oxide bioactivity or the decreased biosynthesis of NO is a central mechanism in endothelial dysfunction. As such, the delivery of exogenous NO is an attractive therapeutic option that has been used to slow the progress of diabetic vascular complications. In this paper, a novel group of hybrid nitric oxide-releasing chrysin derivatives was synthesized. The results indicated that all these chrysin derivatives exhibited in vitro inhibitory activities against aldose reductase and advanced glycation end-products formation. And some of them were even found to increase the glucose consumption of HepG2 cells. Furthermore, all compounds released NO upon incubation with phosphate buffer at pH 7.4. These hybrid ester NO donor prodrugs offer a potential drug design concept for the development of therapeutic or preventive agents for vascular complications due to diabetes.

The potential insulin sensitizing and glucose lowering effects of a novel indole derivative in vitro and in vivo

Thiazolidinediones (TZDs) such as rosiglitazone are antidiabetic peroxisome proliferator-activated receptor γ (PPARγ) agonists. PPARγ agents improve diabetes by increasing insulin sensitivity and enhancing the differentiation of preadipocytes into adipocytes. The present study aimed to identify if 1-(4-chlorobenzoyl)-5-hydroxy-2-methyl-3-indoleacetitic acid (GY3), a newly synthesized indole compound, could enhance adipocytes differentiation and insulin sensitivity. The results showed that both GY3 and rosiglitazone significantly increased the lipid accumulating of 3T3-L1 adipocytes induced by isobutylmethylxanthine, dexamethasone and insulin mixture, but GY3 (not rosiglitazone) failed to increase the lipid accumulation when induced by insulin alone. In addition, GY3- or rosiglitaozne-induced protein expression of GLUT4 and adiponectin was determined by Western blot analysis. GY3 activated PPARα weakly but did not affect PPARγ, while rosiglitazone activated PPARγ significantly, suggesting different mechanisms between GY3 and rosiglitazone on adipocyte differentiation. Furthermore, both GY3 and rosiglitazone enhanced the adiponectin and insulin pathway proteins expression and adiponectin secretion in mature adipocytes, but only GY3 not rosiglitazone elevated gene expression of leptin and resistin. Both GY3 and rosiglitazone enhanced glucose consumption in HepG2 cells especially in the presence of insulin. In the in vivo study, GY3 decreased serum glucose and insulin in db/ db mice, indicating the insulin sensitizing effect might contribute to its antidiabetic mechanism. Altogether, these results suggest that GY3 could improve insulin resistance and lower glucose level, GY3 and its derivatives might be developed as a substitution therapy for diseases with insulin resistance.

Insulin-sensitizing effects of a novel ?-methyl-?-phenoxylpropionate derivative in vitro

To examine the insulin sensitizing effects of a novel alpha-methyl-alpha- phenoxylpropionate derivative YY20 in insulin-sensitive cell lines. The peroxisome proliferator-activated receptor gamma (PPAR gamma) agonist bioactivities of YY20 were detected by a preadipocyte differentiation assay. RT-PCR and Western blotting analysis were used to detect the expression of the target gene or protein. The effects of YY20 on insulin-mediated glucose consumption were determined in the HepG2 human hepatocellular carcinoma line. YY20 could enhance the differentiation of preadipocytes to adipocytes and upregulate the gene expression of PPAR gamma 2, as well as the protein expression of insulin receptor substrate- 1 (IRS-1), glucose transporter-4 (GLUT4), and adiponectin (ACRP30). The effects on GLUT4 and ACRP30 could be reversed by the PPAR gamma inhibitor SR-202. Furthermore, YY20 efficiently reduced glucose consumptions in HepG2 cells after 24 h culture, and the effects were related to insulin and YY20 concentrations. YY20, a potential insulin-sensitizing agent like rosiglitazone, could enhance glucose consumption in HepG2 cells in a concentration- and insulindependent manner. It may improve the insulin resistance associated with type 2 diabetes.

Effect of ecdysterone on glucose metabolism in vitro

The aims of this study was to investigate whether ecdysterone is able to exert glucose-lowering effect on hepatocytes or stimulate the secretion of insulin. HepG2 cell line was used for glucose consumption (GC) studies. At moderate high glucose concentration (11.1 mmol/L), GC of HepG2 cells was increased by 44% to 77% with ecdysterone 1 × 10 − 6 to 1 × 10 − 4 mol/L, which was comparable to that with 1 × 10 − 3 mol/L metformin. The glucose-lowering effect of ecdysterone decreased as the glucose concentration of medium increased. The maximal potency was reached in the presence of 5.5 mmol/L glucose, and the effect was disappeared as the glucose consumption was increased to 22.2 mmol/L. This effect was independent on insulin concentration, which was similar to that of metformin and was different from that of troglitazone, whose glucose-lowering effect was insulin-dependent. Troglitazone had a better antihyperglycemic potency than metformin when insulin was added. Simultaneously, a significant toxicity of troglitazone to HepG2 cells was observed. βTC3 cells were not stimulated by ecdysterone, that is, no secretogogue effect of ecdysterone was observed. The results indicate that ecdysterone is able to exert the glucose-lowering effect in hepatocytes which is insulin-independent, but has no effect on insulin release.