The minimum inhibitory concentration (MIC) of ATB107 is 0.1 μg/mL for M. tuberculosis H37Ra. ATB107 also has high activity against M. tuberculosis H37Rv (MIC: 0.1 μg/mL). All 50 fully susceptible clinical isolates tested are susceptible to ATB107 at 1 μg/mL; of these, 41 (82%) are susceptible to ATB107 at 0.1 μg/mL. The results also show that 67 (83.8%) multidrug-resistant TB (MDR-TB) isolates are susceptible to ATB107 at 1 μg/mL, and 25 (31.3%) isolates are susceptible to ATB107 at 0.1 μg/mL. Results show that the binding ability of ATB107 is well correlated with its concentrations. At the highest concentration of 200 μg/mL, ATB107 can inhibit cell proliferation, with cell survival of about 60%. With the lower concentration of 50 μg/mL, cell survival is more than 80% for ATB107.