Designing, synthesis and characterization of 2-aminothiazole-4-carboxylate Schiff bases; antimicrobial evaluation against multidrug resistant strains and molecular docking.

BACKGROUND: 2-Aminothiazoles are significant class of organic medicinal compounds utilized as starting material for the synthesis of diverse range of heterocyclic analogues with promising therapeutic roles as antibacterial, antifungal, anti-HIV, antioxidant, antitumor, anthelmintic, anti-inflammatory & analgesic agents. EXPERIMENTAL: Eight compounds 1a, 2a-2g were synthesized and characterized by FTIR and NMR ((1)H and (13)C). Evaluation of antibacterial potential against multi-drug resistant clinical isolates was performed and minimum inhibitory concentration (MIC) values were determined. Antifungal activity was also performed. Protein-ligand interactions of compounds with target enzyme were evaluated through docking studies. RESULTS: Resistance profiling of bacterical clinical isolates (MDRs) depicted that some standard drugs used were not active against these MDRs while our synthesized compounds showed good MIC values. Among all the synthesized compounds, 2a and 2b showed significant antibacterial potential towards gram-positive Staphylococcus epidermidis and gram-negative Pseudomonas aeruginosa at MIC 250 µg/mL and 375 µg/mL respectively. Likewise, compound 2d and 2g exhibited inhibitory potential against gram-positive Staphylococcus aureus and gram-negative Escherichia coli at MIC values of 250 and 375 µg/mL respectively. Compound 2b showed maximum antifungal potential against Candida glabrata (ATCC 62934) with a zone of inhibition 21.0 mm as compared to the reference drug nystatin which showed lesser antifungal potential with a zone of inhibition of 19.1 mm. Candida albicans (ATCC 60387) showed maximum sensitivity to compound 2a with a zone of inhibition 20.0 mm. Its antifungal activity is more in comparison to reference drug nystatin with exhibited the zone of inhibition of 19.3 mm. Designed compounds were docked with the target enzyme UDP-N-acetylmuramate/l-alanine ligase. The compound 2b showed highest binding affinity (- 7.6 kcal/mol). CONCLUSIONS: The synthesized compounds showed moderate to significant antibacterial and antifungal potential. It is clear from the binding affinities that compounds having hydroxyl group substituted on benzene ring possess strong binding affinity as compared to other analogues. These designed compounds could be considered to act as antagonists against target UDP-N-acetylmuramate/l-alanine ligase.