Do new N-substituted 3-amino-4-phenyl-5-oxo-pyrazolinecarboxamide derivatives exhibit antitubercular potential?

As a continuation of previous tests concerning new N-substituted 3-amino-4-phenyl-5-oxo-pyrazolinecarboxamide derivatives (R3, R4 and R8) of notable antibacterial activity, their antitubercular potential against different mycobacterial strains was estimated. Tests performed on virulent (reference and clinical) strains of Mycobacterium bovis and Mycobacterium tuberculosis revealed the highest therapeutic potential of R8 derivative: MIC within the range 7.8-15.6 μg/ml and TI (therapeutic index) within the range 46.5-93. Moreover, the synergistic interaction was found between R3, R4 and R8 derivatives and rifampicin, one of the front-line antitubercular drugs. R8/rifampicin mixture in concentrations effective in inhibition of Mycobacterium tuberculosis strain was non-cytotoxic against GMK cells, displaying cell viability approximately 88-97% when compared to control. Molecular docking study enabled to conclude that enoyl acyl carrier protein reductase (InhA) can be considered as a potential molecular target of tested pyrazole derivatives. Although further modifications of chemical structure of the investigated pyrazole derivatives is required, in order to increase their antitubercular efficacy and therapeutic safety, these compounds, in particular R8 compound, can be promising for the treatment of human and bovine tuberculosis.