Facile synthesis, structural evaluation, antimicrobial activity and synergistic effects of novel imidazo[1,2-a]pyridine based organoselenium compounds
Sanjeev Kumar, Nidhi Sharma, Indresh K. Maurya, Aman K.K. Bhasin, Nishima Wangoo, Paula Brandão, Vítor Félix, K.K. Bhasin, Rohit K. Sharma
Department of Chemistry & Centre for Advanced Studies in Chemistry, Panjab University, Chandigarh, 160014, India.
A simple and efficient method has been described to synthesize the hitherto unknown imidazo[1,2-a]pyridine selenides (5a-l) by reaction of 2-chloroimidazo [1,2-a]pyridines with aryl/heteroaryl selenols, generated in situ by reduction of various diselenides with hypophosphorous acid. The crystal structures of 3-nitro-2-(phenylselanyl)-imidazo[1,2-a]pyridine (5a), 2-(mesitylselanyl)-3-nitro-imidazo[1,2-a]pyridine (5d) and 3-nitro-2-(pyridin-2-ylselanyl)-imidazo[1,2-a]pyridine (5e) were confirmed by X-ray crystallography and the DFT calculations were performed to determine various structural parameters which were correlated with the X-ray crystal structures. The synthesized compounds were subjected to antimicrobial evaluation and it was found that compounds 5a and 5jwere active against gram negative bacterium Escherichia coli whereas compound 5ewas active against different fungal strains. Time kill assay was performed to understand the microbial activity of synthesized organoselenium compounds and the toxicity of these compounds was evaluated against human cell lines. Synergistic effects of active compounds 5a and 5e were tested with existing antibiotic drugs which exhibited that the antibiotic combination with synthesized organoselenium compounds efficiently enhanced the antimicrobial activity.