Background: Despite the availability of a variety of antibacterial agents, re-emergence of
pathogenic bacteria is still a serious medical concern. So, identification of new, safer, and selective antibacterial
agents is the key interest in the medicinal chemistry research.
Method: To explore the antimicrobial activity of coumarin-3-carboxamides for a range of bacterial and
fungal strains, twenty eight derivatives were synthesized by the reaction of coumarin-3-carboxylic acid
with a variety of aniline derivatives in the presence of 1,1'-carbonyldiimidazole (CDI). All compounds
were structurally characterized by different spectroscopic techniques EI-MS, HREI-MS, 1H-NMR,
13C-NMR, and evaluated for antimicrobial activities (antibacterial and antifungal).
Results: A number of compounds showed good to weak antibacterial activity against various strains of
Gram-positive and Gram-negative bacteria. Amongst them, compound 28 displayed noticeable inhibition
against five strains of Gram-positive (Bacillus subtilis, Corynebacterium xerosis, Staphylococcus
aureus, Streptococcus faecalis, and MRSA) and four strains of Gram-negative bacteria (Klebsiella
pneumoniae, Pseudomonas aeruginosa, Enterobacter aerogene, and Shigella dysenteria). However,
none of the compounds showed antifungal activity against tested fungi. MIC values were determined
for most of the active compounds 2, 15, and 28 against particular bacterial cultures. In silico studies
were performed on the most active compound 28 in order to specify and verify the target for antibacterial
activity of synthetic coumarin-3-carboxamide derivatives. The cytotoxicity of these compounds on
mammalian cells is unknown yet but we are planning to carry out research on the cytotoxic aspect of
these compounds in future.
Conclusion: The newly identified compounds may serve as lead molecules for the future research regarding
the identification of new antibacterial agents.