Discovery of novel antitubercular 2,10-dihydro-4aH-chromeno[3,2-c]pyridin-3-yl derivatives.

Twenty two novel 2,10-dihydro-4aH-chromeno[3,2-c]pyridin-3-yl derivatives were synthesized by reacting 3-formyl chromone, (sub)-2-amino pyridines, N1-(prop-2-ynyl)arylamides in the presence of indium triflate. The compounds were evaluated their preliminary in-vitro and in-vivo activity against Mycobacterium tuberculosis H37Rv (MTB) and multi-drug resistant M. tuberculosis (MDR-TB). Among them N-[(4aS)-2-(3-methyl-2-pyridinyl)-10-oxo-2,10-dihydro-4aH-chromeno[3,2-c]pyridin-3-yl]methyl-4-ethylbenzenecarboxamide 4d was found to be the most active compound in-vitro with MIC's of 0.22 and 0.07 microg/mL against MTB and MDR-TB respectively. In the in-vivo animal model 4d decreased the bacterial load in lung and spleen tissues with 1.11 and 2.94-log10 protections respectively at 25 mg/kg body weight dose.