Discovery of Novel Insulin Sensitizers: Promising Approaches and Targets.

Insulin resistance is the undisputed root cause of type 2 diabetes mellitus (T2DM). There is currently an unmet demand for safe and effective insulin sensitizers, owing to the restricted prescription or removal from market of certain approved insulin sensitizers, such as thiazolidinediones (TZDs), because of safety concerns. Effective insulin sensitizers without TZD-like side effects will therefore be invaluable to diabetic patients. The specific focus on peroxisome proliferator-activated receptor γ- (PPARγ-) based agents in the past decades may have impeded the search for novel and safer insulin sensitizers. This review discusses possible directions and promising strategies for future research and development of novel insulin sensitizers and describes the potential targets of these agents. Direct PPARγ agonists, selective PPARγ modulators (sPPARγMs), PPARγ-sparing compounds (including ligands of the mitochondrial target of TZDs), agents that target the downstream effectors of PPARγ, along with agents, such as heat shock protein (HSP) inducers, 5'-adenosine monophosphate-activated protein kinase (AMPK) activators, 11ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD1) selective inhibitors, biguanides, and chloroquines, which may be safer than traditional TZDs, have been described. This minireview thus aims to provide fresh perspectives for the development of a new generation of safe insulin sensitizers.

Salidroside-regulated lipid metabolism with down-regulation of miR-370 in type 2 diabetic mice.

Salidroside is known for its pharmacological properties and in particular its antioxidation effects. In recent years, it has been recognized that salidroside plays an important role in treating diabetes. Accumulated evidence suggests that microRNAs may be involved in diabetic lipid disorders. We investigated how salidroside regulates lipid metabolism through miR-370 in vivo and in vitro. After 4 weeks of a high-fat diet, and intraperitoneal injection of streptozotocin (100mg/kg), type 2 diabetes was induced in male C56BL/6J mice. After 4 weeks, mice with fasting blood glucose levels above 7.8mmol/l were divided into five groups: those with diabetes mellitus, and those treated with 40mg/kg, 80mg/kg, and 160mg/kg salidroside, and metformin (480mg/kg), for a further 4 weeks. The hypoglycemic effects of salidroside were consistently demonstrated when measuring fasting blood glucose levels, observing insulin-sensitizing effects, and testing oral glucose tolerance. In addition to this, the expressions of miR-370, and related lipid protein expression in primary hepatocytes, were examined in primary type 2 diabetic mice. The present study has shown that the expression levels of miR-370, SREBP-1 and FAS-1 were significantly elevated in the liver of type 2 diabetic mice. In contrast, the elevated expression levels were reversed by salidroside. The addition of salidroside attenuated the effect of miR-370, and reduced the expression of these lipid metabolism proteins in primary hepatocytes. These findings demonstrate that salidroside can directly decrease the expression of miR-370 in type 2 diabetic mice, and particularly in primary hepatocytes, affecting lipid metabolism in the liver.

Poly[[bis-[µ(2)-8-ethyl-5-oxo-2-(piperazin-1-yl)-5,8-dihydro-pyrido[2,3-d]pyrimidine-6-carboxyl-ato]zinc(II)] dihydrate].

The title compound, {[Zn(C(14)H(16)N(5)O(3))(2)]·2H(2)O}(n) or [Zn(ppa)(2)]·2H(2)O}(n), where ppa = 8-ethyl-5,8-dihydro-5-oxo-2-(1-piperazin-yl)-pyrido(2,3-d)-pyrimidine-6-carboxyl-ate, was synthesized under hydro-thermal conditions. The Zn(II) atom (site symmetry ) exhibits a distorted trans-ZnN(2)O(4) octa-hedral geometry defined by two monodentate N-bonded and two bidentate O,O-bonded ppa monoanions. The extended two-dimensional structure arising from this connectivity is a square grid and the disordered uncoordinated water mol-ecules occupy cavities within the grid. An N-H⋯O hydrogen bond occurs.