Antitubercular activity of substituted 5-oxo-1-thiocarbamoyl-3-pyrazoline-4-alkanoic acid derivatives

Several novel pyrazolin-5-ones prepared by the cyclization of variously substituted thiosemicarbazone derivatives of ethyl formylsuccinate, ethyl acetylsuccinate, and ethyl acetylglutarate were tested for antitubercular activity against Mycobacterium tuberculosis, human type, strain H37Rv, by a tube dilution technique. Minimum inhibitory concentrations (MIC) for these derivatives ranged from 0.05 to 100 mug/ml. The most active compound was ethyl 3-methyl-1-methylthiocarbamoyl-5-oxo-3-pyrazoline-4-acetate (MIC=0.05-0.1 mug/ml).