Haoshu Wu

Insulin releasing and alpha-glucosidase inhibitory activity of ethyl acetate fraction of Acorus calamus in vitro and in vivo

ETHNOPHARMACOLOGICAL RELEVANCE The radix of Acorus calamus L. (AC) is widely used in the therapy of diabetes in traditional folk medicine of America and Indonesia, and we previously reported the insulin sensitizing activity of the ethyl acetate fraction of AC (ACE). AIM OF THE STUDY To investigate the insulin releasing and alpha-glucosidase inhibitory activity of ACE in vitro and in vivo. MATERIALS AND METHODS Insulin releasing and alpha-glucosidase inhibitory effects of different fractions from AC were detected in vitro using HIT-T15 cell line and alpha-glucosidase enzyme. Furthermore, effects of ACE orally on serum glucose were detected in fasted and glucose/amylum challenged normal mice. RESULTS AC and ACE increased insulin secretion in HIT-T15 cells as gliclazide did. As in vivo results, ACE (400 and 800 mg/kg) significantly decreased fasting serum glucose, and suppressed the increase of blood glucose levels after 2g/kg glucose loading in normal mice. In addition, ACE as a mixed-type inhibitor inhibited alpha-glucosidase activity in vitro with an IC(50) of 0.41 microg/ml, and 100mg/kg of it clearly reduced the increase of blood glucose levels after 5 g/kg amylum loading in normal mice. CONCLUSIONS Apart from its insulin sensitizing effect, ACE may have hypoglycemic effects via mechanisms of insulin releasing and alpha-glucosidase inhibition, and thus improves postprandial hyperglycemia and cardiovascular complications.

Insulin sensitizing activity of ethyl acetate fraction of Acorus calamus L. in vitro and in vivo

UNLABELLED Acorus calamus L. (AC), family Araceae, have been used in the Indian and Chinese systems of medicine for hundreds of years. The radix of AC is widely used in the therapy of diabetes in traditional folk medicine of America and Indonesia. AIM OF THE STUDY To investigate the insulin sensitizing activity and antidiabetic effects of the ethyl acetate fraction of AC (ACE). MATERIALS AND METHODS Glucose consumption mediated by insulin was detected in L6 rat skeletal muscle cells. Diabetes and its complications related indexes were monitored after orally administrating to genetically obese diabetic C57BL/Ks db/db mice daily for 3 weeks. RESULTS ACE (12.5 and 25 microg/ml) increased glucose consumption mediated by insulin in L6 cells (p<0.05 and p<0.01). In db/db mice, ACE (100 mg/kg) significantly reduced serum glucose, triglyceride, reinforce the decrease of total cholesterol caused by rosiglitazone (at least p<0.05), and markedly reduced free fatty acid (FFA) levels and increased adiponectin levels (p<0.01 and p<0.05) as rosiglitazone did (p<0.05 and p<0.001). Serum insulin was decreased but not significantly. In addition, ACE decreased the intake of food and water, and did not increase body weight gain whereas rosiglitazone did. CONCLUSIONS Owing to the ability of insulin sensitizing, ACE has the potential to be useful for the treatment of diabetes and cardiovascular complications without body weight gain.

Expression of extracellular superoxide dismutase during adipose differentiation in 3T3-L1 cells

Abstract Obesity is known to be the primary causal component in metabolic syndrome. Adipocytes in obese patients exhibit increased oxidative stress via the activation of reactive oxygen species (ROS)-producing systems and inactivation of antioxidant enzymes. Extracellular superoxide dismutase (EC-SOD) is an anti-inflammatory enzyme that protects cells from the damaging effects of ROS. An earlier report showed that plasma EC-SOD levels in type 2 diabetic patients were significantly and inversely related to body mass index and homeostasis model assessment-insulin resistance index. Moreover, the administration of pioglitazone, an antidiabetic agent, significantly increased the plasma level of EC-SOD. In this report, the expression of EC-SOD was compared to other adipocytokines in mice 3T3-L1 pre-adipocytes. EC-SOD expression levels were increased after the induction of differentiation and then declined, which was similar to adiponectin and transcription factors such as peroxisome proliferator-activated receptor-γ (PPAR-γ) and CCAAT/enhancer-binding protein-α (C/EBP-α). On the other hand, the expression levels of pro-inflammatory adipocytokines, such as tumor necrosis factor-α (TNF-α) and monocyte chemo-attractant protein-1 (MCP-1), increased markedly in the development stage of cells. It was observed that the expression of EC-SOD in differentiated 3T3-L1 cells co-cultured with LPS-stimulated J774 macrophages was up-regulated, while the addition of TNF-α down-regulated EC-SOD and adiponectin expression in adipocytes. It is known that infiltrated and activated macrophages produce extracellular ROS at high levels in adipose tissue. It is possible that the expression of EC-SOD in adipocytes was stimulated to protect them from oxidative stress in the co-culture system.

Effects and molecular mechanisms of the antidiabetic fraction of Acorus calamus L. on GLP-1 expression and secretion in vivo and in vitro

ETHNOPHARMACOLOGICAL RELEVANCE The radix of Acorus calamus L. (AC) is widely used in diabetes therapies in traditional folk medicine from America and Indonesia, and we have previously reported that the ethyl acetate fraction of AC (ACE) acts as an antidiabetic through insulin sensitizing, insulin releasing and alpha-glucosidase inhibitory activities. The present study is designed to investigate the effects and molecular mechanisms of ACE on glucagon-like peptide-1 (GLP-1) expression and secretion related to its hypoglycemic effects. MATERIALS AND METHODS The hypoglycemic effect of ACE (100mg/kg, i.g.) was confirmed by testing blood glucose levels or via oral glucose tolerance test (OGTT) in streptozotocin (STZ) induced hyperglycemic mice, db/db diabetic mice and diet-induced obese (DIO) mice. Plasma insulin, GLP-1 levels and intestinal GLP-1 related gene expression were determined in STZ-induced and db/db diabetic mice. The in vitro effects of ACE (12.5μg/ml) on the expression and secretion of GLP-1 were detected in NCI-H716 intestinal L-cells, and the correlation between ACE and molecules in the Wnt signaling pathway was further explored. RESULTS ACE (100mg/kg) significantly lowered fasting blood glucose in STZ-induced and db/db diabetic mice and improved the OGTT in DIO mice. Insulin releasing and islet protective effects, along with the increased secretion of GLP-1, were observed. The expression of proglucagon gene (gcg) and post-translational processing gene prohormone convertase 3 (pc3) and the GLP-1 content in the culture medium of L-cells notably increased after the ACE treatment (12.5μg/ml). At the same time, β-catenin nuclear translocation occurred, and its downstream protein cyclin D1 was activated, showing the involvement of Wnt signaling. CONCLUSIONS ACE might activate Wnt signaling to increase the gene expression of gcg and pc3 and exert incretin effects, including insulinotropic and islet protection, to lower blood glucose levels via elevated GLP-1 secretion either directly or indirectly.

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.

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

AbstractAim:To examine the insulin sensitizing effects of a novel α-methyl-α-phenoxylpropionate derivative YY20 in insulin-sensitive cell lines.Methods:The peroxisome proliferator-activated receptor γ (PPARγ) 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.Results:YY20 could enhance the differentiation of preadipocytes to adipocytes and upregulate the gene expression of PPARγ2, as well as the protein expression of insulin receptor sub-strate-1 (IRS-1), glucose transporter-4 (GLUT4), and adiponectin (ACRP30). The effects on GLUT4 and ACRP30 could be reversed by the PPARγ 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.Conclusion:YY20, a potential insulin-sensitizing agent like rosiglitazone, could enhance glucose consumption in HepG2 cells in a concentration- and insulin-dependent manner. It may improve the insulin resistance associated with type 2 diabetes.

Terpenoids from Curcuma wenyujin increased glucose consumption on HepG2 cells

Thirty four terpenoids, including two new cadinane-type sesquiterpenoids containing conjugated aromatic-ketone moieties, curcujinone A (1) and curcujinone B (2), were isolated from 95% ethanol extract of the root tubers of Curcuma wenyujin. Their structures were determined by spectroscopic methods, especially 2D NMR and HRMS techniques. The relative and absolute configurations of 1 and 2 were identified by quantum chemical DFT and TDDFT calculations of the 13C NMR chemical shifts, ECD spectra, and specific optical rotations. All compounds and extracts were evaluated for their anti-diabetic activities with a glucose consumption model on HepG2 Cells. The petroleum fraction CWP (10μg/mL) and compounds curcumenol (4), 7α,11α-epoxy-5β-hydroxy-9-guaiaen-8-one (5), curdione (17), (1S, 4S, 5S 10S)-germacrone (18), zederone (20), a mixture of curcumanolide A (25) and curcumanolide B (26), gajutsulactone B (27), and wenyujinin C (30) showed promising activities with over 45% increasing of glucose consumption at 10μM.

Oleanolic acid derivative DKS26 exerts antidiabetic and hepatoprotective effects in diabetic mice and promotes glucagon‐like peptide‐1 secretion and expression in intestinal cells

Glucagon‐like peptide‐1 (GLP‐1) is an important target for diabetes therapy based on its key role in maintaining glucose and lipid homeostasis. This study was designed to investigate antidiabetic and hepatoprotective effects of a novel oleanolic acid derivative DKS26 in diabetic mice and elucidate its underlying GLP‐1 related antidiabetic mechanisms in vitro and in vivo.

Oleanolic acid derivative DKS26 exerts antidiabetic and hepatoprotective effects in diabetic mice and promotes GLP-1 secretion and expression in intestinal cells

Glucagon‐like peptide‐1 (GLP‐1) is an important target for diabetes therapy based on its key role in maintaining glucose and lipid homeostasis. This study was designed to investigate antidiabetic and hepatoprotective effects of a novel oleanolic acid derivative DKS26 in diabetic mice and elucidate its underlying GLP‐1 related antidiabetic mechanisms in vitro and in vivo.

Insulin-releasing activity of a series of phenylalanine derivatives

A series of phenylalanine derivatives were synthesized and their biological activities were evaluated. Compounds (S)-3 and (R)-3 exhibited more potent insulin-releasing activity than that of nateglinide, compound (S)-3 also showed insulin-sensitizing activity in vitro. Both compounds were tested for hypoglycemia effect in vivo.