Design and Synthesis of 2-Substituted Benzothiazole Derivatives as Antioxidant and Antimicrobial Agents

Background: An upsurge in the number of antibiotic-resistant microbial infections has warranted the discovery and development of new antibiotics. This is a matter of great concern for effective therapy for a search of novel antimicrobial agents. Literature has a number of reports of involvement of oxidative stress due to an imbalance between the generation and neutralization of free radicals in many diseases. Heterocyclic compounds have been involved in the treatment of various disorders. Benzothiazole is one such heterocyclic nucleus having benzene ring merged with the thiazole ring. Among the various substitutions possible in this nucleus, substitutions at position-2 have already been reported with potential bioactivities. Thus, different substituted compounds have been synthesized which could serve as antimicrobials and antioxidants. Methods: Benzothiazole derivatives (B1-B7) were synthesized by two-step reactions and the structures were confirmed through infrared, mass and NMR spectroscopy. The compounds were evaluated for in vitro antioxidant and antimicrobial activities using standard methods. Results: The results of antibacterial and antifungal activity showed that compound B4 exhibited maximum activity against all the tested strains of microorganisms with the zone of inhibition 17.1-18.5 mm and MIC value 1.1-1.5 μg/mL. Compound B5 exhibited potent antioxidant activity. Conclusion: The compounds substituted with halogen on the aryl ring showed increased antimicrobial activity as seen in the case of compound B4 (6-fluoro). The compounds substituted with a hydroxyl group (B5) exhibited good antioxidant activity.