Design synthesis and preliminary evaluation of 2cyano pyrrolidine derivatives for their DPP4 inhibiting activity

Abstract

The current therapeutic agents for Type 2 diabetes (like Insulin, Sulphonylureas, Biguanides, and#945;-Glucosidase inhibitors, PPAR agonist and GLP-1 agonist), although effective in increasing insulin secretion, are associated with some safety issue and undesirable side effects, including hypoglycemia, abnormalities in cardiovascular responses and and#946;-cell apoptosis. DPP-4 inhibitors offer several potential advantages over existing therapies including decreased risk of hypoglycemia, potential for weight loss, and the potential for regeneration and differentiation of pancreatic and#946;-cells. Moreover, DPP-4 inhibitors can also be administered orally. Among all DPP-4 inhibitor derivatives, 2-Cyano pyrrolidine-based inhibitors have been studied most extensively. Apart from behaving as a proline mimic, the presence of the nitrile on the five-membered ring was shown to provide (i) nanomolar inhibition of DPP-4 and (ii) chemical stability adequate for oral administration. Most widely explored 2-cyano pyrrolidine class of DPP-4 inhibitors contains cyano or nitrile function that binds with catalytic serine and forms an imidate to show slow tight-binding kinetics. But, same cyanopyrrolidines undergo intramolecular cyclization of the free amino group at P2 site onto the electrophilic cyano or nitrile group at P1 site and leads to the stability issue. Therefore, 1-(2-chloroacetyl) pyrrolidine-2-carbonitrile intermediate moiety was fused with different heterocyclic derivatives like 1,3,4-thiadiazoles, Benzothiazoles, Phenyl Thiazoles, 1,3,4-oxadiazoles and 3,4-dihydroquinazolins to get novel 2-cyanopyrrolidine derivatives. All synthesized DPP-4 inhibitor derivatives were screened by DPP-4 inhibitor screening assay method which employs fluorogenic substrate, Gly-Pro-Aminomethylcoumarin (AMC), to measure DPP-4 activity. DPP cleave the peptide bond and releases the free AMC group which results in fluorescence and it was analyzed using an excitation wavelength of 350-360 nm and emission wavelength of 450-465 nm. newline newline