Synthesis and biological evaluation of novel indolo[2,3-c]isoquinoline derivatives

A new series of novel compounds 1-tert-butyl-9-substituted-12H-indolo[2,3-c]isoquinolino[5,6-c]-1,2,4-triazoles (4a–4c), 10-substituted-2-phenyl-1,13-dihydroindolo[2,3-c]isoquinolino[5,6-c]-1,2,4-triazines (5a–5l), 2-(10-substituted-7H-indolo[2,3-c]isoquinolin-5-yl)-4-phenylphthalazin-1-ones (6a–6c), 2-[2-(10-substituted-7H-indolo[2,3-c]isoquinolinyl)hydrazinecarbonyl]benzoic acid (7a–7c), and 2-(10-substituted-7H-indolo[2,3-c]isoquinolin-5-yl)phthalazine-1,4-diones (8a–8c) were synthesized. The structures of these newly synthesized compounds were confirmed by their spectral studies and elemental analysis. These compounds have been screened for their antimicrobial, antitubercular, antioxidant, and cytotoxic activities. Compounds 4b, 5a, 5g, 5h, 6a, 6b, and 7b exhibited the maximum zone of inhibition against Staphylococcus aureus. Compounds 5d and 6c exhibited the maximum zone of inhibition against Pseudomonas aeruginosa. Compounds 7a and 8c showed maximum zone of inhibition against Aspergillus niger. Compounds 5k and 8c showed maximum zone of inhibition against Aspergillus flavus. Compounds 4a (MIC-1.6 µg/ml) and 5 h (MIC-0.2 µg/ml) exhibited promising antitubercular activity against Mycobacterium tuberculosis H37Rv strain. Compounds 4b, 4c, 5a, 5c, 5e, 5h, 6a, 6b, 6c, 8a, and 8b exhibited good radical scavenging activity compared with standards. Compounds 4b, 4c, 5a, 5c, 5g, 6a, and 8b exhibited maximum reducing ability. Compounds 4a and 5h exhibited 100 % cell lysis at concentration 10 µg/ml.