Synthesis, antioxidant, and antiurease activities of novel benzimidazole-based 1,3,4-thiadiazole derivatives

In this study, we report the synthesis and characterisation of five new benzimidazole-based 1, 3, 4-thiadiazole derivatives (5a–e) and the evaluation of their antioxidant and antiurease activities. The structures were confirmed by NMR (1H, 13C) and LC/TOF–MS analyses (spectra are given in the supplementary information). Biological assays (DPPH, ABTS, iron-reducing power, urease inhibition) revealed that compound 5e (bearing a 4-nitrophenyl substituent) exhibited the strongest urease inhibition (EC50 = 0.1296 ± 0.0260 µM), surpassing thiourea. One-way ANOVA revealed significant differences in urease inhibition between the compounds (p<0.001). Post-hoc Tukey tests confirmed that compound 5e was more effective than several other compounds. The compounds exhibited moderate and comparable antioxidant activities. The first SAR study shows that electron-withdrawing substituents increase urease inhibition, whereas electron-donating groups increase the reducing power. Comparison with earlier reported triazole analogues shows scaffold-dependent changes in bioactivity. These findings support thiadiazoles as promising dual-function agents for oxidative stress and urease-associated pathologies.