Synthesis and Antioxidant Activity of 2-Substituted-5-Nitro Benzimidazole Derivatives

Objective: This study was conducted to synthesise some 2-substituted-5-nitro benzimidazole derivatives to evaluate their antioxidant activity. Methods: The titled compounds were synthesised by sodium metabisulfite mediated reaction of 4-nitro-1, 2-phenylenediamine with a number of para-substituted benzaldehydes. The antioxidant activity was evaluated by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging method. Results: All the compounds exhibited good antioxidant activity having IC₅₀ values in the range of 3.17 to 7.59 µg/ml while that of standard butylated hydroxytoluene (BHT) was 18.42 µg/ml. Conclusion: Among the synthesised compounds, compounds 3a-c have been shown to possess the most prominent antioxidant activity which might be attributed due to the presence of chloro, bromo and fluoro substituents in the molecule. The compounds may act as the future lead(s) for the development of potential antioxidant compounds.