The Novel Derivatives of 3-(iminomethyl)-2H-chromen-2-one with Thiourea and Piperazine Structural Motive: Rationale, Synthesis, Antimicrobial and Anti-TB Evaluation

The emergence and rapid spread of Multi Drug Resistant (MDR) infectious microbial flora embracing a variety of bacterial, fungal as well as mycobacterium strains are causing a threat to public health worldwide. To cure this dilemma, a library of two series of coumarin based Schiff bases (4a-j) and thiourea derivatives (6a-j) was rationalized, synthesized and accessed for their in vitro antibacterial activity (against Staphylococcus aureus MTCC 96, Bacillus subtilis MTCC 441, Escherichia coli MTCC 739, Pseudomonas aeruginosa MTCC 741 and Klebsiella pneumoniae MTCC 109) and antifungal activity (against Aspergillus niger MTCC 282, Aspergillus fumigates MTCC 343, Aspergillus clavatus MTCC 1323, Candida albicans MTCC 183) using broth dilution technique. Furthermore all the newly synthesized congeners were also examined for in vitro antituberculosis activity (against Mycobacterium tuberculosis H37Rv) using BACTEC MGIT method as well as MIC method on Lowenstein–Jensen medium. Final analogous 4a, 6b, 6i and 6j possessing chloro or methyl group were proved to be highly potent antimicrobial agents. All the synthesized derivatives were well characterized by their IR, 1H NMR, 13C NMR, elemental analysis as well as mass spectroscopy.