Available on line www.jocpr.com Journal of Chemical and Pharmaceutical Research __________________________________________________ ISSN No: 0975-7384 CODEN(USA): JCPRC5 J. Chem. Pharm. Res., 2010, 2(3):368-373 368 In-vitro screening of quinoxaline-2-one derivatives for antitubercular activity Gopal Krishna Rao a , Ramaling B. Kotnal*and PN Sanjay Pai b a Department of Pharmaceutical Chemistry, Al-Ameen College of Pharmacy, Hosur Road, Near Lalbagh Main Gate, Bangalore b Department of Quality Assurance, Al-Ameen College of Pharmacy, Hosur Road, near Lalbagh Main Gate, Bangalore _________________________________________________________________ ABSTRACT A series of ethyl 2-[(3-methyl-2-oxoquinoxalin-1(2H)-yl)acetyl]-3-oxo-2,3-dihydro-1H- pyrazole-4-carboxylate derivatives were prepared and evaluated for their antitubercular activities. All compounds were screened for in vitro antitubercular activity against Mycobacterium tuberculosis H 37 Rv (MTB). Minimum inhibitory concentrations were determined and interpreted for Mycobacterium tuberculosis H 37 Rv according to the procedure of the approved macro dilution reference method of antimicrobial susceptibility testing. Among all the compounds synthesized, (GKR 4b, 4c, and 4f) were found to be the most active compounds against MTB with MIC (25 μg/mL). Key words: Schiff’s bases, antitubercular activity, minimum inhibitory concentration (MIC). ______________________________________________________________________________ INTRODUCTION Tuberculosis (TB), a highly infectious disease primarily caused by Mycobacterium tuberculosis, is one of the oldest recorded human afflictions and remains today a leading cause of impoverishment, human suffering and death [1-4]. The majority of deaths resulting from TB infection occur in poverty stricken regions of the developing world. While TB in humans is primarily due to infection with M. tuberculosis, several other species of the M. tuberculosis complex, namely M. bovis, M. africanum, M. microti and M. canettii may also cause the disease [5]. Recently two additional species have been suggested as belonging to the M. tuberculosis complex: M. caprae and M. pinnipedii [6].