ORIGINAL RESEARCH Synthesis, antibacterial, and antitubercular studies of some novel isatin derivatives K. Murali • R. Avinash • R. Kirthiga • Scott G. Franzblau Received: 24 July 2011 / Accepted: 4 January 2012 Ó Springer Science+Business Media, LLC 2012 Abstract The rise in clinical significance of multi drug- resistant bacterial pathogens has directed us to synthesize a novel series of isatin derivatives and characterize them by IR, NMR, mass spectral, and elemental analysis. Com- pounds were evaluated for their preliminary in vitro anti- bacterial activity against Gram-positive (Staphylococcus aureus, Staphylococcus epidermis, Micrococcus luteus, Bacillus cereus) bacteria and were screened for antituber- cular activity against Mycobacterium tuberculosis H37Rv strain by microplate alamar blue assay (MABA) method. Some synthesized compounds showed very good antibac- terial and antitubercular activities. Keywords Antitubercular Á Antibacterial Á Isatin Á Mannich bases Introduction During the past few decades, the alarming rate in the incidence of life-threatening infections caused by multiple drug-resistant (MDR) Gram-positive organisms particu- larly methicillin-resistant Staphylococcus aureus (MRSA) and methicillin- resistant S. epidermis (MRSE) are becoming a significant health concern throughout the world. As they do not respond to the current clinical drug therapy, the morbidity and mortality rate among the human population is rising, which in turn poses a serious challenge for the scientific community (Rybak and Akins, 2001; Livermore, 2000; Cetinkaya et al., 2000; Cassel and Mekalanos, 2001). Besides these pathogens, the most infectious Mycobacterium tuberculosis H3R V , a slow- growing Gram-positive bacterium, is also a life-threaten- ing pathogen and is the etiologic agent of contagious tuberculosis (TB). As per the estimated data of the World Health Organization (WHO), Southeast Asia and Africa show an alarming rise in TB cases, where it develops at a rate of more than one per second. TB is one of the common infectious diseases known to mankind. About two billion people are infected with tuberculosis every year, nearly half a million MDR-TB cases emerge and more than 1, 30,000 people die of MDR-TB. MTB has two features that render it the deadliest infectious disease to date. Its high infectivity or virulence and its ability to become dormant for subsequent reactivation phenomena that leads to the deadliest synergy with Acquired Immune Deficiency Syndrome (AIDS). As a result, TB is also the leading cause of death for AIDS patients. Moreover, the emergence of MDR-TB is severely hampering TB treat- ment, and there is an urgent need to develop new thera- peutic agents. In view of this situation, in 1993 the WHO declared TB a global emergence (Boshoff et al., 2002). K. Murali (&) Department of Chemical Engineering, Universitat Rovira i Virgili, 26 Av Paisos Catalans, 43007 Tarragona, Spain e-mail: drmuralinano@gmail.com R. Avinash Department of Pharmaceutical Chemistry, C.L. Baid Metha College of Pharmacy, Jyothi Nagar, Rajiv Gandhi Salai, Thorapakkam, Chennai 600097, Tamil Nadu, India R. Kirthiga Bangalore Antibiotics & Biologicals Pvt Ltd., Salem 636 007, Tamil Nadu, India S. G. Franzblau Institute of Tuberculosis Research, University of Illinois, Chicago, IL, USA 123 Med Chem Res DOI 10.1007/s00044-012-9971-7 MEDICINAL CHEMISTR Y RESEARCH