Baicalin ameliorates insulin resistance and regulates hepatic glucose metabolism via activating insulin signaling pathway in obese pre-diabetic mice.

BACKGROUND: Diabetes belongs to the most prevalent metabolic diseases worldwide, which is featured with insulin resistance, closely associated with obesity and urgently needs to be treated. Baicalin, belonging to natural flavonoids, has been reported to inhibit oxidative stress or inflammatoin. PURPOSE: This study investigated the properties of baicalin on modulating abnormal glucolipid metabolism, as well as the underlying in-vitro and in-vivo mechanisms. METHODS: Insulin-resistant (IR)-HepG2 cells were stimulated by dexamethasone (20 µM) and high glucose (50 mM) for 48 h and incubated with or without baicalin or metformin for another 16 h. Male C57BL/6 J mice were fed with a high-fat diet (HFD, 60 % kcal% fat) during the total 14 weeks. Obese mice were then administered with baicalin (50 and 100 mg/kg) or vehicle solution everyday through oral gavage during the last 4-week period. Moreover, baicalin metabolisms in vitro and in vivo were determined using UPLC/MS/MS to study its metabolism situation. RESULTS: Exposure to dexamethasone and high glucose damaged the abilities of glycogen synthesis and glucose uptake with elevated oxidative stress and increased generation levels of advanced glycation end-products (AGEs) in HepG2 cells. These impairments were basically reversed by baicalin treatment. Four-week oral administration with baicalin ameliorated hyperglycemia and dyslipidemia in HFD-induced obese and pre-diabetic mice. Downregulation of IRS/PI3K/Akt signaling pathway accomplished with reduced GLUT4 expression and enhanced GSK-3ß activity was observed in insulin resistant HepG2 cells as well as liver tissues from pre-diabetic mice; and such effect was prevented by baicalin. Moreover, baicalin and its matabolites were detected in IR-HepG2 cells and mouse plasma. CONCLUSION: The study illustrated that baicalin alleviated insulin resistance by activating insulin signaling pathways and inhibiting oxidative stress and AGEs production, revealing the potential of baicalin to be a therapeutic natural flavonoid against hepatic insulin and glucose-lipid metabolic disturbance in pre-diabetes accompanied with obesity.

Panax Notoginseng Protects against Diabetes-Associated Endothelial Dysfunction: Comparison between Ethanolic Extract and Total Saponin.

Previous studies revealed a cardioprotective potential of Panax notoginseng to relieve acute myocardial infarction and focal cerebral ischemia-reperfusion. However, whether P. notoginseng protects endothelial function in diabetes and the underlying mechanisms remain to be explored. P. notoginseng contains several chemical components including saponins, which are commonly believed as the major bioactive ingredients. The present study was aimed to examine and compare the vaso-protective effects of the ethanolic extract of P. notoginseng (PNE) and total saponin (PNS). Both aortas and carotid arteries were isolated from male C57BL/6J mice for ex vivo treatment with risk factors (high glucose or tunicamycin) with and without the presence of PNS and PNE. Diabetic model was established by feeding the mice with a high-fat diet (45% kcal% fat) for 12 weeks, while PNS and PNE were administrated by oral gavage at 20 mg/kg/day for another 4 weeks. Ex vivo exposure to high glucose impaired acetylcholine-induced endothelium-dependent relaxations in mouse aortas, decreased phosphorylation of AMPK and eNOS, and induced endoplasmic reticulum (ER) stress and oxidative stress. These effects were reversed by cotreatment of PNS and PNE with PNS being more potent. Furthermore, the vaso-protective effects were abolished by Compound C (AMPK inhibitor). Chronic treatment with PNS and PNE improved endothelium-dependent relaxations and alleviated ER stress and oxidative stress in aortas from high-fat diet-induced obese mice. PNE was more effective to improve glucose sensitivity and normalize blood pressure in diabetic mice. The present results showed that PNS and PNE reduced ER stress and oxidative stress and, subsequently, improved endothelial function in diabetes through AMPK activation. This study provides new inspiration on the therapeutic potential of P. notoginseng extract against vascular diseases associated with metabolic disorders.

The anti-inflammatory potential of Portulaca oleracea L. (purslane) extract by partial suppression on NF-κB and MAPK activation.

Portulaca oleracea L. (Purslane) has great potential as food and traditional drugs in several countries. The purpose of this study was to evaluate the anti-inflammatory effects of purslane extract on lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Purslane extracts significantly reduced LPS-induced synthesis of NO in a dose-dependent manner, as well as the expression levels of iNOS and COX-2. The productions of TNF-α and IL-6 were also significantly reduced at the higher dose of 400 µg/ml. Meanwhile, the expression levels of P65, p-P65, p-MEK and p-IκB-α were inhibited dose-dependently. The nuclear translocation of P65 was partially prevented by the extract, which explained the inhibition of NF-κB pathway. In addition, three reported flavonoids, named luteolin, kaempferol and quercitrin, were identified in the extract, which might be responsible for its anti-inflammatory effects. Above all, our research has partially proved that purslane could be considered as a natural anti-inflammatory agent in further applications.