Antibacterial and antitubercular evaluation of dihydronaphthalenone-indole hybrid analogs

A new series of indole appended dihydronaphthalenone hybrid analogs (5a-t) have been synthesized through the Lewis acid catalyzed Michael addition of indoles to the arylidene/hetero arylidene ketones. All the synthesized derivatives are well characterized through the ¹ H-NMR, ¹³ C-NMR, HRMS spectroscopic techniques, compound 5r was further confirmed through single crystal X-ray analysis and screened for antibacterial and antitubercular activities. Among the synthesized compounds, the minimum inhibition concentration of 5l (against Escherichia coli) and 5o & 5p (against E. coli & Staphylococcus aureus) was found to be as low as 3.12 μg/ml as compared to the standard antibacterial drug ciprofloxacin 2.5 μg/ml. In antitubercular activity, compounds 5o and 5p with minimum inhibition concentration 6.25 μg/ml were found to be comparable with that of the drugs Pyrazinamide 5 μg/ml and Streptomycin 5 μg/ml. Compounds 5i, 5j, 5m, 5n, 5q, and 5r also showed promising activity against group of organisms tested.