Novel oxadiazole derivatives as potent inhibitors of α-amylase and α-glucosidase enzymes: Synthesis, in vitro evaluation, and molecular docking studies

Alpha-amylase and alpha-glucosidase enzyme inhibition is an effective and rational approach for controlling postprandial hyperglycemia in type II diabetes mellitus (DM). Several inhibitors of this therapeutic class are in clinical use but are facing challenges of safety, efficacy, and potency. Keeping in view the importance of these therapeutic inhibitors, in this study we are reporting 10 new oxadiazole analogs 5 (a-g) & 4a (a-c) as antidiabetic agents.  The newly synthesized derivatives 5 (a-g) & 4a (a-c) were characterized using different spectroscopic techniques including FTIR,1HNMR, 13CNMR, and elemental analysis data. All compounds were screened for their in vitro α-amylase and α-glucosidase enzyme inhibitory potential, while two selected compounds (5a and 5g) were screened for cytotoxicity using MTT assay. Two analogues 5a and 4a (a) exhibited strong inhibitory potential against α-glucosidase enzyme, i.e., IC50 value=12.27±0.41 µg/ml and 15.45±0.20 µg/ml, respectively in comparison with standard drug miglitol (IC50 value=11.47±0.02 µg/ml) whereas, one compound 5g demonstrated outstanding inhibitory potential (IC50 value=13.09±0.06 µg/ml) against α-amylase enzyme in comparison with standard drug acarbose (IC50 value=12.20±0.78 µg/ml). The molecular interactions of these active compounds in the enzymes’ active sites were evaluated following molecular docking studies.  Our results suggested that these new oxadiazole derivatives (5a, 5g & 4a (a)) may act as promising drug candidates for the development of new alpha-amylase and alpha-glucosidase inhibitors. Therefore, we further recommend in vitro and in vivo pharmacological evaluations and safety assessments.