Synthesis and biological evaluation of novel carbazole hybrids as promising antimicrobial agents

Two series of carbazole analogs of 8-methoxy -carbazole-3-carboxamides (series-1) and carbazolyl substituted rhodanines (series-2) were synthesized through facile synthetic routes. All the final compounds from these two series were evaluated for their preliminary in vitro antifungal and antibacterial activity against four fungal ( Candida albicans , Cryptococcus neoformans , Cryptococcus tropicalis and Aspergillus niger ) and four bacterial ( Staphylococcus aureus , Bacillus subtilis , Escherichia coli and Pseudomonas aeruginosa ) strains, respectively. Among the tested compounds, 6d , 6e and 6f (series-1) displayed promising antifungal and antibacterial activity, especially against C. neoformans and S. aureus. In addition, compound 6f displayed notable antimicrobial activity (MIC: 6.25 microg/mL) against clinical isolates of C. albicans and C. neoformans (MIC: 12.5 microg/mL). From the second series, 15f , 15g , 15i and 16f exhibited significant antifungal and antibacterial activity, especially against C. neoformans and S. aureus . The most active compound 15i displayed a prominent antimicrobial activity against C. neoformans (MIC: 3.125 microg/mL) and S. aureus (MIC: 1.56 microg/mL), respectively.