Anti-diabetic activity and potential mechanism of total flavonoids of Selaginella tamariscina (Beauv.) Spring in rats induced by high fat diet and low dose STZ.

To evaluate the anti-diabetic effects of the total flavonoids of Selaginella tamariscina (Beauv.) Spring (TFST), and to explore the pertinent mechanism. High fat diet and STZ (35 mg/kg) induced diabetic rats were administered with TFST at graded oral doses (100, 200 and 400mg/kg/day, ig.) for 8 weeks. A range of parameters, including blood glucose and lipid, serum insulin and glucagon, glucose tolerance, were tested to evaluate its anti-diabetic effects. The determination of protein expression of peroxisome proliferator activated receptor γ (PPAR-γ) in adipose tissue and insulin receptor substrate 1 (IRS-1) in hepatic and skeletal muscle tissues was used to study the mechanism of TFST. Moreover, the preliminary study of TFST on the antioxidant activity was performed. The TFST possessed anti-diabetic activities as shown by the decreased serum levels of fast blood glucose (FBG), glycosylated hemoglobulin A1C (HbA1c), triglyceride (TG), total cholesterol (TC), free fatty acid (FFA), low density lipoprotein-cholesterol (LDL-C) and glucagon, as well as increased serum levels of high density lipoprotein-cholesterol (HDL-C), insulin and C-peptide. TFST also improved the oral glucose tolerance test (OGTT) to a certain degree. Furthermore, TFST increased the protein expression of PPAR-γ in adipose tissue, and increased the protein expressions of IRS-1 in hepatic and skeletal muscle tissues. These benefits were associated with increased superoxide dismutase (SOD) and decreased malondialdehyde (MDA) in serum. TFST exert beneficial effects on hyperglycosemia and hyperlipoidemia in diabetic rats possibly through regulating the levers of PPAR-γ in adipose tissue and IRS-1 in hepatic and skeletal muscle tissues.

Zheng XK ，Zhang L ，Wang WW ，Wu YY ，Zhang QB ，Feng WS ... -  《-》

Antihyperlipidaemic and antioxidant effect of the total flavonoids in Selaginella tamariscina (Beauv.) Spring in diabetic mice.

To investigate the antidiabetic, antihyperlipidaemic and antioxidant activity of total flavonoids in Selaginella tamariscina (Beauv.) Spring (TFST) in a mouse model of diabetes. Normal mice, mice fed with a high-fat emulsion diet and streptozotocin (STZ)-induced diabetic mice were treated with TFST for 6 weeks. Serum glucose, insulin and lipid, hepatic steatosis, production of the protein visfatin and antioxidant indices were evaluated. TFST significantly decreased the concentration of fasting blood glucose, total cholesterol, triglycerides and low-density-lipoprotein cholesterol, while it increased the levels of insulin and high-density-lipoprotein cholesterol in diabetic mice. TFST also improved the results of the oral glucose tolerance test to a certain degree. Furthermore, both the free fatty acid levels in the liver and hepatic steatosis were ameliorated by TFST treatment. These changes may be be associated with decreased production of visfatin. Administration of TFST also significantly decreased the levels of malondialdehyde, nitric oxide and inducible nitric oxide synthase and increased the content of glutathione and the activity of superoxide dismutase, catalase, glutathione peroxidase and glutathione-S-transferase in the liver. No change in blood glucose levels were observed in the normal mice treated with TFST. TFST showed an excellent effect in reducing the high blood glucose level but had no effect on normal blood glucose level. The antidiabetic activity of TFST could be explained by its antioxidant and antihyperlipidaemic activity, which finally elevated the insulin sensitivity of liver.

Zheng XK ，Wang WW ，Zhang L ，Su CF ，Wu YY ，Ke YY ，Hou QW ，Liu ZY ，Gao AS ，Feng WS ... -  《-》

Evaluation of hypoglycemic effects of polyphenols and extracts from Penthorum chinense.

Penthorum chinense Pursh has a long history of use as a health food and folk medicine to alleviate "heat"-associated disorders, promote circulation and diuresis, and to treat liver problems, and to protect the spleen. In this study we provide experimental evidence for the clinical use of Penthorum chinense in the treatment of diabetes mellitus. The aim of the study was to investigate the hypoglycemic effects of extracts and active constituents from Penthorum chinense. High fat diet and STZ (35mg/kg) induced diabetic rats were administered with Penthorum chinense extract at graded oral doses (150 and 300mg/kg/day, ig.) for 2 weeks. A range of parameters, including blood glucose and lipid, serum insulin, glucose tolerance, were tested to evaluate its anti-hyperglycemic effects. Moreover, oral starch tolerance test (OSTT) was performed to test the level of postprandial glucose after administrating Penthorum chinense extract. In vitro study, the Penthorum chinense extracts and purified Penthorum chinense polyphenols were tested for α-amylase inhibitory activity. The polyphenols were determined by UPLC-Q-TOF mass spectrometry and NMR. The Penthorum chinense extract possessed anti-hyperglycemic activities as shown by the decreased serum levels of glycosylated hemoglobulin A1C (HbA1c), triglyceride(TG), total cholesterol (TC), and low density lipoprotein-cholesterol (LDL-C), as well as increased serum levels of high density lipoprotein-cholesterol (HDL-C) and insulin. Penthorum chinense extract also improved the oral glucose tolerance test (OGTT) to a certain degree. Moreover, the OSTT study showed that in diabetic rats, the extract (600mg/kg) caused a significant hypoglycemic effect with a blood glucose reduction of 42% at 60min. To identify the active constituents, three polyphenols, pinocembrin-7-O-[4″,6″-hexahydroxydiphenoyl]-β-d-glucose (1), pinocembrin-7-O-[3″-O-galloyl-4″, 6″-hexahydroxydiphenoyl]-β- d-glucose (2), and thonningianin A (3) were isolated from Penthorum chinense. Compounds 1-3 moderately inhibited α-amylase activity, with IC50 values of 0.14, 0.03, and 0.08µmol/ml, respectively. The folk medicinal plant, Penthorum chinense produced a moderated anti-hyperglycemic effect on STZ-induced diabetic rats and starch induced postprandial hyperglycemic mice.

Huang D ，Jiang Y ，Chen W ，Yao F ，Huang G ，Sun L ... -  《-》

Healing effects of sumac (Rhus coriaria) in streptozotocin-induced diabetic rats.

Doğan A ，Çelik İ 《-》

Flavonoids extracted from mulberry (Morus alba L.) leaf improve skeletal muscle mitochondrial function by activating AMPK in type 2 diabetes.

Mulberry (Morus alba L.) leaves have been widely applied to controlling blood glucose as a efficacious traditional Chinese medicine or salutary medical supplement. The extracts of mulberry leaf suppress inflammatory mediators and oxidative stress, protect the pancreatic β-cells and modulate glucose metabolism in diabetic rats. Our previous studies and others have shown that mulberry leaf extract has excellent therapeutic effects on type 2 diabetes mellitus (T2DM), however, the underlying mechanism remains to be studied. Skeletal muscle insulin resistance (IR) plays an important role in the pathogenesis of T2DM. The aim of this study was to investigate the effects and mechanisms of Mulberry leaf flavonoids (MLF) in L6 skeletal muscle cells and db/db mice. L6 skeletal muscle cells were cultured and treated with/without MLF for in vitro studies. For in vivo studies, the db/db mice with/without MLF therapy were used. Coomassie brilliant blue staining and α-SMA immunofluorescence staining were used to identify the differentiated L6 cells. Glucose level and ATP level of L6 myotubes were performed by optical density detection and cell viability was performed by MTT method. Mitochondrial membrane potential of L6 myotubes was detected by JC-1 fluorescent staining. ROS level of L6 myotubes was detected by DCFH-DA fluorescent staining. The body weight, food intake, and blood glucose of the mice were measured in different treatment days. Oral glucose tolerance test (OGTT), starch glucose tolerance test (STT) and insulin tolerance test (ITT) were performed in mice. Glycated hemoglobin, glycated serum protein, insulin, liver and muscle glycogen, total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-c) and low-density lipoprotein cholesterol (LDL-c) of the mice were detected by corresponding kit. The pathologic change of pancreas and skeletal muscle of mice were performed by H & E staining. Immunohistochemistry staining was used to detect the GLUT4 and p-AMPK expressions in skeletal muscle in mice. GLUT4, CPT-1, NRF1, COXIV, PGC-1α, and p-AMPK expression levels in L6 cells and mice were detected by western bolt assay. MLF and metformin significantly ameliorated muscle glucose uptake and mitochondrial function in L6 muscle cells. MLF also increased the phosphorylation of AMPK and the expression of PGC-1α, and up-regulated the protein levels of m-GLUT4 and T-GLUT4. These effects were reversed by the AMPK inhibitor compound C. In db/db mice, MLF improve diabetes symptoms and insulin resistance. Moreover, MLF elevated the levels of p-AMPK and PGC-1α, raised m-GLUT4 and T-GLUT4 protein expression, and ameliorated mitochondrial function in skeletal muscle of db/db mice. MLF significantly improved skeletal muscle insulin resistance and mitochondrial function in db/db mice and L6 myocytes through AMPK-PGC-1α signaling pathway, and our findings support the therapeutic effects of MLF on type 2 diabetes.

Meng Q ，Qi X ，Fu Y ，Chen Q ，Cheng P ，Yu X ，Sun X ，Wu J ，Li W ，Zhang Q ，Li Y ，Wang A ，Bian H ... -  《-》