Design, Synthesis, Molecular Docking, and Biological Evaluation of Novel 1,2,4-Oxadiazole-Based Derivatives as Inhibitors of Trypsin, ALDH2, and iNOS

Objective: A series of novel derivatives based on a 1,2,4-oxadiazole scaffold were designed, synthesized, and evaluated in vitro for their inhibitory activity against trypsin, aldehyde dehydrogenase 2 (ALDH2), and inducible nitric oxide synthase (iNOS), aiming to identify potential anticancer agents. Methods: The synthesized 1,2,4-oxadiazole derivatives were characterized by NMR, IR spectroscopy, and elemental analysis. Their biological activity was evaluated through in vitro enzyme inhibition assays and supported by molecular docking studies using MOE software. Results and Discussion: The results demonstrated that compounds (Va), (Vb), and (VIIb) exhibited potent trypsin inhibition, exceeding that of the reference compound benzamidine hydrochloride. Additionally, derivatives (IIIa) and (IIIb) also showed notable trypsin inhibitory activity. Compounds (Va) and (VIa) displayed significant ALDH2 inhibition, comparable to that of tetraethylthiuram disulfide. Furthermore, derivatives (VIa), (VIb), and (VIIIb) effectively inhibited iNOS. The pronounced inhibitory activities of the most potent compounds (Va, VIa, and VIIb) may be attributed to strong interactions within the active sites of trypsin and ALDH2, as supported by molecular docking studies. Compound (Va) also exhibited favorable physicochemical properties, suggesting its potential as a promising lead compound for further drug development. Conclusions: 1,2,4-Oxadiazole derivative (Va) appears to be a promising anticancer lead compound for further investigation and development.