Design, Synthesis and Biological Evaluation of 2-Aminobenzimidazole Derivatives as DPP4 Inhibitors

Background: The objective of the research was to examine the DPPIV inhibitor activity of synthetic derivatives of 2-aminobenzimidazole derivatives by the in-vivo method. Methods: Molecular docking was performed using homology model of receptors to identify the binding sites for the inhibitory activity of diabetes by means of- CDocker energy using the Discovery Studio (DS) 4.5 Novel 2-amino benzimidazole derivatives were synthesized from orthophenylene diamine with cyanogens bromide. The synthesized compounds were identified by IR,1HNMR,13CNMR, and MASS spectroscopic techniques. The products were analyzed for their DPPIV inhibitory effects on Wistar Albino rat. Results: The results revealed that benzimidazole with para-aminobenzoic acid possesses best DPPIV inhibitor activity. 2- amino benzimidazole incorporated with aromatic compounds were synthesized and assessed for their DPP-IV inhibitor activity. Conclusion: 2- amino benzimidazole with para-aminobenzoic acid can be used as a lead compound for the development of a new class of DPP-IV inhibitor.

The preanalytical stability of glucagon as measured by liquid chromatography tandem mass spectrometry and two commercially available immunoassays

Background One of the main challenges in the measurement of glucagon is the premise that it is unstable in human plasma. Traditionally, protease inhibitors have been used to prevent its degradation; however, their use is controversial. Here, we investigated the optimal method of sample collection for glucagon, with measurement by liquid chromatography tandem mass spectrometry (LC-MS/MS) and two commercially available immunoassays. Methods Blood from healthy fasting volunteers (n = 10) was processed under a variety of preanalytical conditions including collection in EDTA vs. lithium heparin tubes and the addition of aprotinin and/or a dipeptidyl-peptidase IV (DPPIV) inhibitor. Additionally, the effect of freeze thaw was assessed. Plasma glucagon concentrations were measured by LC-MS/MS and two commercially available immunoassays (HTRF® sandwich immunoassay, Cisbio and Milliplex MAP Human Metabolic Hormone Panel, Merck Millipore). Results A systematic bias of Milliplex > LC-MS/MS > HTRF was noted and plasma glucagon concentrations were significantly different between methods (Milliplex vs. LC-MS/MS P < 0.01; Milliplex vs. HTRF P < 0.0001; LC-MS/MS vs. HTRF P < 0.001). The addition of aprotinin, DPPIV inhibitor or a combination of aprotinin and DPPIV inhibitor had no effect on plasma glucagon concentrations when compared to ‘non-stabilized’ samples or each other. Whether samples were taken in EDTA tubes or lithium heparin tubes made no difference to plasma glucagon concentrations. These findings were consistent for all three methods. Plasma glucagon concentrations were not significantly different after two freeze–thaw cycles (performed on samples in EDTA tubes containing aprotinin and DPPIV inhibitor). Conclusions This study demonstrates that glucagon is stable in both EDTA and lithium heparin tubes when stored at −80℃. Furthermore, the addition of aprotinin and DPPIV inhibitors is unnecessary.

Abstract 371: DPPIV Inhibitor MK0626 Prevents Western Diet Induced Renal Injury via Suppression of Kidney Tissue Ras

Objectives: Obesity is an independent risk factor for development and progression of renal injury. High fructose corn syrup consumption has coincided with the obesity epidemic in the United States. High fructose (60%) diets have been demonstrated to be associated with elevation in BP and worsening insulin resistance along with renal injury via increased hepatic production of uric acid. Recently, DPPIV inhibitors have been shown to improve diabetic changes and sodium excretion, effects that are beyond glycemic control. Therefore, the renal protective benefits of DPPIV inhibition in a clinically relevant Western diet fed mouse model were examined. Methods: Mice fed a high fat/high fructose (WD) diet for 16 weeks and given a DPPIV inhibitor MK0626 in their diet were examined for metabolic parameters, inflammation, kidney renin-angiotensin system (RAS) and oxidative stress. Renal injury was assessed by biochemical, immunohistological and electron microscopy techniques. In vitro , angiotensin II (Ang II) effects on OKP-PTCs were assessed for mechanism. Results: MK0626 ameliorated WD-induced increases in serum uric acid, oxidative stress and RAS. WD induced suppression of IL-10 was reversed by MK0626. There was a tendency to improve HOMA-IR by MK0626 but no effect on BP and body weights. Diet induced DPPIV activation in the plasma and kidney of WD mice was abrogated by MK0626 (~80%). WD mice were characterized by increased proteinuria (~3-fold), mesangial expansion and podocyte effacement and these changes were prevented by MK0626. In addition, the PTC endocytosis protein megalin and basilar canalicular network and mitochondrial ultrastructure abnormalities were reversed by MK0626. WD mice had decreased sodium excretion which was improved by MK0626. Ang II directly increased DPPIV activity and sodium hydrogen exchanger activity in PTCs and decreased megalin protein, which was effectively prevented by MK0626. Conclusion: Thus, WD induced increases in DPPIV activity is associated with elevations in uric acid, renal RAS, inflammation and oxidative stress which may result in renal injury. These results suggest that DPPIV inhibitors prevent WD induced renal injury and offer a novel therapy for diabetic and obesity associated renal disease.