Synthesis and Biological Evaluation of Imidazo-Thiadiazole-Linked Benzisoxazole Hybrids as Dual α-Glucosidase and α-Amylase Inhibitors With Antioxidant Potential

Abstract

Type 2 diabetes mellitus (T2DM) remains a major global health challenge, necessitating the discovery of novel therapeutics with improved safety and efficacy. In this study, a series of imidazo-thiadiazole-linked benzisoxazoles (1–20) was synthesized and evaluated for dual inhibitory activity against α-glucosidase and α-amylase enzymes. Most compounds showed potent enzyme inhibition, with compounds 3 and 4 exhibiting superior activity against α-glucosidase and α-amylase (IC₅₀ = 1.56 and 3.01 µM for compound 3; IC₅₀ = 3.24 and 5.82 µM for compound 4) compared to the standard drug acarbose (IC₅₀ = 14.85 and 15.25 µM). Enzyme kinetic studies revealed both competitive and uncompetitive modes of inhibition. Structure–activity relationship (SAR) analysis highlighted that para-substituted electron-withdrawing groups significantly enhanced inhibitory potential. Antioxidant activity was assessed using cupric reducing antioxidant capacity (CUPRAC), ferric reducing antioxidant power (FRAP), and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assays, with compound 2 displaying the strongest effect. Molecular docking supported the in vitro results, revealing favorable interactions with key catalytic residues of target enzymes. ADME/T profiling confirmed desirable pharmacokinetic properties and drug-likeness. Overall, these findings suggest that the synthesized hybrids represent promising multifunctional candidates for T2DM therapy, combining potent enzyme inhibition, antioxidant activity, and favorable drug-like profiles.