Design and Discovery of Novel 1,3,5-Triazines as Dipeptidyl Peptidase-4 Inhibitor against Diabetes

This study aims at synthesizing novel di-morpholine 1,3,5-triazine derivatives as antidiabetic agent via inhibition of dipeptidyl peptidase-4 (DPP-4). The molecules were developed via sequential nucleophilic reaction to afford target derivatives 5(a–f) and subsequently tested for inhibitory potency against DPP iso-enzymes, such as DPP-4, DPP-8, and DPP-9. The in vitro inhibition assay suggested that these derivatives prominently and selectively inhibit DPP-4 over ­DPP-8 and DPP-9. These molecules also showed no presence of cardiotoxicity, as confirmed by no activity against human Ether-à-go-go related gene channel. The study disclosed compound 5c as the most potent inhibitor of DPP-4 with IC 50 of 1.10 nmol/L as compared to the standard. Compound 5c was further evaluated for oral glucose tolerance test (OGTT) and antidiabetic activity in ICR mice and Wistar rats, respectively. In OGTT, compound 5c showed dose-dependent ­improvement of glucose tolerance with a maximum at 30 mg/kg. It also showed reduction in area under the curve from 0 to 120 min, similar to alogliptin (standard). In Wistar rats, compound 5c causes reduction in the blood glucose level, total cholesterol, triglyceride, low density lipoprotein (LDL) and very LDL level as compared to the diabetic control group, whereas the level of high-density lipoprotein was found to be increased. Compound 5c causes improvement in antioxidant defense mechanism, as confirmed via improving superoxide dismutase, catalase, glutathione peroxidase and reducing the malondialdehyde level as compared to normal control group rats.