ATP synthase inhibitor 3 (compound PT6) is an orally active inhibitor of mycobacterial F-ATP synthase ( IC 50 =0.788 μM). ATP synthase inhibitor 3 inhibits the growth of Mycobacterium tuberculosis H37Rv strain (ATCC-27294) in vitro and depletes intracellular ATP levels at an IC 50 value of 30μM.