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

Abstract

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-pyrazolylmethanethione (6i) was found to be most active agent with a minimum inhibitory concentration of 0.96μg/mL.

Keywords::

• Pyrazoline
• isoniazid, isothiocyanate, INH resistant mycobacterium tuberculosis and antitubercular agent

Acknowledgements

The author (M.Shahar Yar) wishes to express his thanks to the University Grant Commission – New Delhi, India for the research award and we thank the Tuberculosis Antimicrobial Acquisition and Coordinating Facility (TAACF), National Institute of Allergy and Infections Diseases Southern Research Institute/GW Long Hansen's Disease Center, Colorado State University Birmingham, Alamba, USA, for the in vitro anti-mycobacterial screening and Dr Kiran Smith, National Cancer Institute – USA, for valuable suggestions.