Synthesis, in vitro α‐Glucosidase Inhibition, DFT Calculations, and Molecular Docking Studies of Some New Substituted 2,5‐Bis(pyrazolyl)‐1,3,4‐oxadiazoles

Abstract

A pivotal feature of present research study is the synthesis of some new 2,5‐bis(pyrazolyl)‐1,3,4‐oxadiazoles as promising α‐glucosidase inhibitors. In this regard, a facile reaction scheme was designed to afford 1,3,4‐oxadiazole ring. In search of the most favourable reaction condition, a model reaction was first carried out between 1,3‐diphenyl‐1H‐pyrazole‐4‐carbohydrazide (3) and 1,3‐diphenyl‐1H‐pyrazole‐4‐carboxylic acid (4 a) using phosphorous oxychloride (POCl3). The results emanated from this model reaction were utilized to prepare other derivatives to highlight the scope of current synthetic approach and the structures of the prepared molecules were characterized from spectroscopic techniques. These derivatives were further investigated for their α‐glucosidase inhibitory potentials. 2,5‐Bis(1,3‐diphenyl‐1H‐pyrazol‐4‐yl)‐1,3,4‐oxadiazole (5 a) and 2‐(3‐(4‐bromophenyl)‐1‐phenyl‐1H‐pyrazol‐4‐yl)‐5‐(1,3‐diphenyl‐1H‐pyrazol‐4‐yl)‐1,3,4‐oxadiazole (5 c) displayed strong in vitro inhibitory activities with IC50 73.1±1.13 μM and IC50 87.3±1.12 μM respectively with least toxicity profiles. Molecular docking and computational studies including geometry optimization of synthesized molecular systems, calculations of their orbital energies, and molecular electrostatic potential (MEP) surface maps further helped to establish structural and electronic properties contributing towards their bioactivity. The electrophilicity index significantly quantifies the biological activity. The experimental and computational data altogether facilitated in understanding the therapeutic attributes of these versatile scaffolds in relation to their α‐glucosidase inhibition.