Antitubercular activity of novel substituted 4,5-dihydro-1H-1-pyrazolylmethanethiones

A series of, anilino-5-(substituted) phenyl-3-(4-hydroxy-3-methylphenyl)-4,5-dihydro-1H-1-pyrazolylmethanethione and 2-chloroanilino-5-(substituted) phenyl-3-(4-hydroxy-3-methylphenyl)-4,5-dihydro-1H-1-pyrazolylmethanethione were synthesized by the reaction between hydrazine hydrate and the chalcones (3a-k) followed by condensation with the appropriate aryl isothiocyanate which yielded the N-substituted pyrazoline derivatives. These were tested for their in-vitro anti-mycobacterial activity against INH resistant Mycobacterium tuberculosis (INHR MTB) using the BACTEC 460 radiometric system. Compound 2-chloroanilino-5-(2,6-dichlorophenyl)-3-(4-hydroxy-3-methylphenyl)-4,5-dihydro-1H-1-pyrazolyl-methanethione (6i) was found to be most active agent with a minimum inhibitory concentration of 0.96 microg/mL.