Synthesis and preliminary antimicrobial evaluation of some new 6-methoxyquinoline-3-carbonitrile derivatives

A series of new 6-methoxyquinoline-3-carbonitrile derivatives were synthesized using a variety of synthetic routes. The newly synthesized compounds have been characterized by IR, 1H NMR, and mass spectral data followed by elemental analysis. All of the synthesized compounds were evaluated for their in-vitro antimicrobial activity against Streptococcus pneumonia and Bacillus subtilis as examples for Gram-positive bacteria, Pseudomonas aeruginosa and Escherichia coli as examples for Gram-negative bacteria, and Aspergillus fumigatus, Syncephalastrum racemosum, Geotriucum candidum and Candida albicans as representative examples of fungi. The majority of tested compounds showed moderate activities against wide range of selected organisms. Among the tested compounds, the ester derivative 7b and the thioether derivative 9c showed the highest antimicrobial activity against gram-positive strains while the highest activity against gram-negative strains was observed in case of 7b, 7d and 9b while compound 7e found more active than Amphotericin B against three fungal species.