Virtual Screening-Based Discovery of Potent Hypoglycemic Agents: In Silico, Chemical Synthesis and Biological Study.

BACKGROUND: Dipeptidyl peptidase IV has been reported to be an important target for the development and discovery of new therapies for diabetes mellitus type II. OBJECTIVE: The main aim of this study was to discover chemical entities that target the inhibition of DPP IV and feature potent hypoglycemic action. METHODS: A structure-based virtual screening was applied to discover new hypoglycemic agents. Molecular docking was performed to compute the binding free energies. Molecular dynamics simulations were done to evaluate the binding stability of resulted hits. RESULTS: Seven small non-peptide potential inhibitors of Dipeptidyl peptidase IV with 3-imino-4-(4- substituted phenyl)-1, 2, 5-thiadiazolidine-1,1-dioxide scaffold were discovered. The binding free energies ranged from -24.50 to -36.06 kJ/mol. Molecular dynamics simulations revealed high stability of all protein-ligand complexes with low root mean square deviation over 10 ns simulation time. The tested compounds expressed a significant reduction in blood glucose level up to 90% with excellent oral glucose tolerance test after 120 minutes of injection in a diabetes mellitus type II animal model. A promising release of insulin was observed with a potential hypoglycemic activity for all compounds. CONCLUSION: The virtual screening was successful to discover potent hypoglycemic agents with drug-like properties that may need more consideration for future studies and development.

Tempol ameliorates cardiac fibrosis in streptozotocin-induced diabetic rats: role of oxidative stress in diabetic cardiomyopathy.

Long-standing diabetes is associated with increased oxidative stress and cardiac fibrosis. This, in turn, contributes to the progression of cardiomyopathy. The present study was sought to investigate whether the free radical scavenger, 4-hydroxy-2,2,6,6-tetramethyl piperidinoxyl (tempol) can protect against diabetic cardiomyopathy and to explore the specific underlying mechanism(s) in this setting. Diabetes was induced in rats by a single intraperitoneal injection dose of streptozotocin (50 mg/kg). These animals were treated with tempol (18 mg kg(-1) day(-1), orally) for 8 weeks. Our results showed significant increases in collagen IV and fibronectin protein levels and a marked decrease in matrix metalloproteinase-2 (MMP-2) activity measured by gelatin-gel zymography alongside elevated cardiac transforming growth factor (TGF)-ß level determined using ELISA or immunohistochemistry in cardiac tissues of diabetic rats compared with control. This was accompanied by an increased in the oxidative stress as evidenced by increased reactive oxygen species (ROS) production and decreased antioxidant enzyme capacity along with elevated lactate dehydrogenase (LDH) and creatine kinase (CK-MB) serum levels as compared with the control. Tempol treatment significantly corrected the changes in the cardiac extracellular matrix, TGF-ß, ROS or serum LDH, CK-MB levels, and normalized MMP-2 activity along with preservation of cardiac tissues integrity of diabetic rats against damaging responses. Moreover, tempol normalized the elevated systolic blood pressure and improved some cardiac functions in diabetic rats. Collectively, our data suggest a potential protective role of tempol against diabetes-associated cardiac fibrosis in rats via reducing oxidative stress and extracellular matrix remodeling.

Mutation-, aging-, and gene dosage-dependent accumulation of neuroserpin (G392E) in endoplasmic reticula and lysosomes of neurons in transgenic mice.

Mutations in human neuroserpin gene cause an autosomal dementia, familial encephalopathy with neuroserpin inclusion bodies (FENIB). We generated and analyzed transgenic mice expressing high levels of either FENIB-type (G392E) or wild-type human neuroserpin in neurons of the central nervous system. G392E neuroserpin accumulated age-dependently in neurons of the neocortex, thalamus, amygdala, pons, and spinal cord of homozygous transgenic mice. Such accumulations were not observed in hemizygous transgenic mice nor in transgenic mice for wild-type neuroserpin. In differential centrifugation of brain homogenates, G392E neuroserpin recovered in the nucleus-rich fraction dramatically increased along with aging, suggesting that the aggregations gradually increase their densities presumably by their conversion into heavier and more compact configurations. In immunoelectron microscopical analyses, immunopositivities for G392E neuroserpin were found not only in endoplasmic reticulum but also in lysosomes. G392E neuroserpin transgenic mice were much more susceptible to seizures induced by kainate administration than nontransgenic mice. Overall, G392E neuroserpin accumulated in the central nervous system neurons of transgenic mice in mutation-, aging-, and gene dosage-dependent manners. The established transgenic mice will be valuable to elucidate not only mechanisms for the formation of G392E neuroserpin aggregations but also pathways for the degradation and/or clearance of the already formed aggregations in neurons.